- A Mechanistic Study of the Methanol Dehydration Reaction on γ-Alumina Catalyst
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The dehydration of methanol over a porous γ-Al2O3 catalyst was studied using periodic square-wave modulation of the feed to a microcatalytic reactor.Online mass spectrometry was used to obtain wave forms at the exit of the reactor for methanol, dimethyl ether, water, and a carrier gas.The reaction was studied over the temperature range of 230-350 deg C.At lower temperatures, the dimethyl ether wave form went first through a maximum, decreased to a constant level during the on cycle, and then went through a second maximum at the beginning of the off cycle.At higher temperatures where the conversions increased, the relative intensity of the maximum to the level part of the wave form continuously decreased until no maximum could be observed at temperatures above 280 deg C.Water was found to have a phase lag of about 4 s with respect to dimethyl ether over the studied temperature range.The shape of the wave forms was explained in terms of a reaction mechanism which involved reactions of surface species formed from the adsorption of methanol on the γ-Al2O3 surface.The species considered were molecularly adsorbed methanol, methoxy, and hydroxyl groups.The mechanism contained two parallel reaction pathways for the production of dimethyl ether.One pathway was the reaction between molecularly adsorbed methanol and methoxy species, and the other was the reaction between two methoxy species.For the production of water, only a single step of recombination of surface hydroxyls was considered in the mechanism.Equations for the material balances of the species considered in the mechanism were numerically integrated to generate wave forms with the same shape as observed in the experimental data.
- Schiffino, Rinaldo S.,Merrill, Robert P.
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- Vapor-Phase Carbonylation of Methanol over Tin-on-Active Carbon Catalysts
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It was found that a number of metals or metal oxides showed catalytic activities for the vapor-phase carbonylation of methanol in the presence of methyl iodide (CH3I) promoter under the conditions of 250 deg C and 10 atm (1 atm = 1.01325x105 Pa), when they were supported on active carbon.Particularly, tin and lead showed high activities.The catalytic activity of the metallic tin increased with the process time over 5 h while that of the unreduced tin catalyst increased for more than 10 h to reach the same level.The catalytic performances of the tin on active carbon were similar to those of the nickel on active carbon which have been already reported.It was suggested that the active species of the tin catalyst was some kind of metal compounds which was highly dispersed on active carbon and was able to be incorporated in the redox cycle.
- Yagita, Hiroshi,Omata, Kohji,Shikada, Tsutomu,Fujimoto, Kaoru
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- A novel sol-gel approach to highly condensed silicas at low temperature
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We have discovered new Meerwein's reagent-catalyzed solgel polycondensations, which provide highly condensed silica Q4 and biphenylylene silica T3 as amorphous gels with marginal silanols starting from TEOS and 4,4′-bis(triethoxysilyl)biphenyl (BTEBph), respectively. We propose a plausible pathway for this protocol with possible silyloxonium intermediates.
- Jorapur, Yogesh R.,Mizoshita, Norihiro,Maegawa, Yoshifumi,Nakagawa, Hiroki,Hasegawa, Takeru,Tani, Takao,Inagaki, Shinji,Shimada, Toyoshi
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- Hydrogenation of CO2 to dimethyl ether on La-, Ce-modified Cu-Fe/HZSM-5 catalysts
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Cu-Fe-La/HZSM-5 and Cu-Fe-Ce/HZSM-5 bifunctional catalysts were prepared and applied for the direct synthesis of dimethyl ether (DME) from CO2 and H2. The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption, H2-temperature programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The results showed that La and Ce significantly decreased the outer-shell electron density of Cu and improved the reduction ability of the Cu-Fe catalyst in comparison to the Cu-Fe-Zr catalyst, which may increase the selectivity for DME. The Cu-Fe-Ce catalyst had a greater specific surface area than the Cu-Fe-La catalyst. This promoted CuO dispersion and decreased CuO crystallite size, which increased both the DME selectivity and the CO2 conversion. The catalysts were stable for 15 h.
- Qin, Zu-Zeng,Zhou, Xin-Hui,Su, Tong-Ming,Jiang, Yue-Xiu,Ji, Hong-Bing
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- Fine Control of the Pore-opening Size of the Zeolite Mordenite by Chemical Vapour Deposition of Silicon Alkoxide
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Chemical vapour deposition (c.v.d.) of Si(OCH3)4 on the H form of mordenite has been carried out in order to control the pore-opening size without affecting its acidic properties.It has been shown that Si(OCH3)4 is deposited irreversibly on the zeolite.Because the molecular size of the alkoxide is larger than the pore size, the alkoxide does not enter the pore and the silicon compound is deposited on the external surface.The alkoxide may be deposited by reaction with hydroxide, thus covering the external surface of zeolite crystal after subsequent reactions.Calcination with oxygen removes the hydrocarbon residue and produces silica-coated H-mordenite (SiHM).The SiHM thus obtained has been characterized by temperature-programmed desorption (t.p.d.) of NH3, adsorption experiments and X-ray photoelectron spectroscopy.The deposition of the alkoxide does not change the acidity but reduces the size of pore opening.Enrichment of Si on the external surface of the zeolite is confirmed.One can therefore conclude that SiO2 covers the external surface of the zeolite, thus reducing the effective size of the pore opening.The pore size is effectively reduced by ca. 0.1 and 0.2 nm upon formation of 1-2 and 3 molecular layers of silicon oxide, respectively.
- Niwa, Miki,Kato, Satoshi,Hattori, Tadashi,Murakami, Yuichi
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- Boroaluminosilicate Catalysts with the ZSM-5 Structure Synthesized in Nonalkaline Media
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Aluminosilicate and borosilicate (containing up to 3.80 B atoms per unit cell) zeolites with the ZSM-5 structure have been prepared by the "fluoride route" and studied by a range of techniques.Contrary to numerous studies (which investigated the conversion of methanol at much higher temperatures), trans-but-2-ene and not ethylene is the first hydrocarbon desorbed from the catalyst at temperatures below 200 deg C.We propose a mechanism for this reaction which does not require the formation and desorption of ethylene to the gas phase.The reaction of the methoxy intermediate formed on an acid site with the CH3OH molecule gives surface ethoxy groups, which are alkylated by further methanol molecules to give propoxy and butoxy groups.
- Sulikowski, Bogdan,Klinowski, Jacek
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- An intermetallic Pd2Ga nanoparticle catalyst for the single-step conversion of CO-rich synthesis gas to dimethyl ether
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Well-defined Pd/Ga-nanoparticles were prepared and used as a precursor for the methanol active component in a bifunctional syngas-to-dimethyl ether catalyst. In situ X-ray absorption spectroscopy experiments were employed both to unravel the initial formation of the active catalyst phase in reductive H2 atmosphere and to further monitor changes of the nanoparticles under conditions of dimethyl ether synthesis at a pressure up to 20 bar (250 °C). The catalytic studies were conducted using simulated biomass-derived, CO-rich syngas in a continuous-flow reactor, with the bifunctional catalyst offering the two types of active sites, i.e. for methanol synthesis (Pd/Ga nanoparticles) and its subsequent dehydration (γ-Al2O3), in close proximity. As compared to the conventional Cu/Zn-based reference catalyst prepared via a similar procedure, the Pd/Ga-based catalyst showed a promising activity together with a notable stability with time on stream and a high temperature tolerance (up to 300 °C). A kinetic model which considers the individual reactions involved in direct DME synthesis based on power law equations was used to fit the experimental data, and the apparent activation energies were compared to the Cu/Zn-based catalyst.
- Gentzen, Manuel,Doronkin, Dmitry E.,Sheppard, Thomas L.,Grunwaldt, Jan-Dierk,Sauer, J?rg,Behrens, Silke
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- SYNERGISTIC EFFECT OF HOMOGENEOUS RUTHENIUM-RHODIUM CATALYSTS FOR METHANOL HOMOLOGATION
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Homogeneous solutions containing both ruthenium and rhodium complexes and methyl iodine are shown to exhibit a synergistic effect for the homologation of methanol to ethanol.Reactions were studied at pressures from 100 to 175 atm and at temperatures from 160 to 240 deg C.The highest selectivities were obtained with excess of ruthenium complexes present.Under these reaction conditions no evidence for cluster catalysis was found.
- Pursiainen, Jouni,Karjalainen, Kauko,Pakkanen, Tapani A.
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- Influence of metal oxide modification of alumina on the dispersion and activity of vanadia catalysts
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Alumina was modified with 10 wt % MOx (MOx = TiO2, ZrO2, La2O3, or MgO) prior to its impregnation with 12 wt % vanadia. The catalysts VTiAl, VZrAl, VLaAl, and VMgAl were characterized by X-ray diffraction (XRD), electron spin resonance (ESR), FT-Raman spectroscopy, 51V solid state nuclear magnetic resonance (51V NMR), and oxygen chemisorption. The activities of the catalysts were determined by methanol partial oxidation and their acid-base properties were evaluated for the decomposition of 2-propanol. XRD and FT-Raman spectroscopy indicated the formation of bulk TiO2 and ZrO2 on the titania and zirconia modified alumina. 51V solid state NMR results suggest the presence of both octahedrally and tertrahedrally coordinated vanadia species in the catalysts VTiAl, VZrAl, and VAl and the presence of tetrahedrally coordinated vanadia species in the catalysts VLaAl and VMgAl. ESR spectra recorded at ambient temperature showed the presence of V4+ ions having axial symmetry. Oxygen chemisorption results indicated an enhanced number of reducible vanadia sites, i.e., redox sites in the modified catalysts. Metal oxide modification is found to influence significantly the surface coverage and the methanol partial oxidation activity of vanadia supported on alumina. With proper MOx modification enhanced reducibility of vanadia could be attained, which in turn makes the partial oxidation reaction of methanol more facile.
- Lakshmi, L. Jhansi,Alyea, Elmer C.,Srinivas,Kanta Rao
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- Synthesis of lower olefins from dimethyl ether in the presence of zeolite catalysts modified with rhodium compounds
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The catalytic properties of zeolite catalysts modified with rhodium compounds in the synthesis of olefins from dimethyl ether (DME) and methanol (MeOH) have been studied. The optimum concentration of rhodium in the composition of a zeolite catalyst has been determined. It has been shown that one of the possible precursors of ethylene in the conversion of DME is ethanol, which, under reaction conditions, can be formed through both the DME isomerization and methanol homologation stages.
- Kolesnichenko,Goryainova,Biryukova,Yashina,Khadzhiev
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- Methanol adsorption and dehydrogenation over stoichiometric and non-stoichiometric hydroxyapatite catalysts
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On hydroxyapatite of stoichiometric composition (Ca/P = 1.65), methanol decomposes at 600°C, in the absence of oxygen, to produce predominantly carbon monoxide. As the Ca/P ratio decreases, the selectivities to formaldehyde and dimethyl ether increase to ca. 80% at a value of Ca/P equal to 1.51. IR spectra show that methoxy groups are formed on the surface of both the stoichiometric and non-stoichiometric catalysts. Both IR and temperature-programmed desorption experiments suggest that for the decomposition of methanol, acidic sites are required for the dissociative adsorption whereas basic sites facilitate the C-H bond scission via carboxylate groups and the consequent formation of CO and H2.
- Matsumura, Yasuyuki,Moffat, John B.
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- Thermal Decomposition of Dimethyl Methylphosphonate over Manganese Oxide Catalysts
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The thermal oxidative decomposition of dimethyl methylphosphonate (DMMP) has been studied over amorphous manganese oxide (AMO) and Al2O3-supported manganese oxide catalysts. The reaction was carried out using air as the oxidant at te
- Segal, Scott R.,Cao, Lixin,Suib, Steven L.,Tang, Xia,Satyapal, Sunita
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- Effect of Mo dispersion on the catalytic properties and stability of Mo-Fe catalysts for the partial oxidation of methanol
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Mo-Fe catalysts with different Mo dispersions were synthesized with fast (Cat-FS, 600 r·min?1) or slow stirring speed (Cat-SS, 30 r·min?1) by the coprecipitation method. Improving the stirring speed strengthened the mixing of the solution and increased the dispersion of particles in the catalyst, which exhibited favorable activity and selectivity. The byproduct (dimethyl ether (DME)) selectivity increased from 2.3% to 2.8% with Cat-SS, while it remained unchanged with Cat-FS in a stability test. The aggregation of particles and thin Mo-enriched surface layer decreased the catalyst surface area and slowed down the reoxidation of reduced active sites with Cat-SS, leaving more oxygen vacancies which promoted the formation of DME by the nonoxidative channel.
- Han, Minghan,Zhang, Shuai
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- Synthesis of isoalkanes over a core (Fe-Zn-Zr)-shell (zeolite) catalyst by CO2 hydrogenation
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A kind of core-shell catalyst with Fe-Zn-Zr as the core and a zeolite (HZSM-5, Hbeta, and HY) as the shell was synthesized by a simple cladding method. The catalyst has an obvious confinement effect on the synthesis of isoalkanes by CO2 hydrogenation. Especially, the Fe-Zn-Zr@HZSM-5-Hbeta catalyst with a double-zeolite shell exhibits an extraordinary high i-HC/t-HC ratio.
- Wang, Xiaoxing,Yang, Guohui,Zhang, Junfeng,Chen, Shuyao,Wu, Yingquan,Zhang, Qingde,Wang, Junwei,Han, Yizhuo,Tan, Yisheng
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- Methyl-Transfer Reactions. 7. System with CH3OSO(1+) Intermediate
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Methyl chlorosulfite with antimony pentachloride in thionyl chloride initially at dry ice temperature is a very powerful methylating system.It methylates sulfones, methyl chloride, and even to some extent dimethyl sulfate.The active methylating species is apparently the cation CH3OSO(1+).Dimethyl sulfite is decomposed catalytically by methyl trifluoromethanesulfonate to dimethyl ether and sulfur dioxide, and the same cation appears to be intermediate.The mechanism includes an exchange of the methyl groups between the two esters, allowing a practical synthesis of methyl -d3 triflate.Dimethyl sulfite does not methylate detectably on sulfur.
- Christie, J. Joseph,Lewis, Edward S.,Casserly, Edward F.
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- Antimony Pentafluoride/Graphite Catalyzed Oxidative Carbonylation of Methyl Halides with Carbon Monoxide and Copper Oxides (or Copper/Oxygen) to Methyl Acetate
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Superacidic antimony pentafluoride/graphite catalyzed oxidative carbonylation of methyl halides with carbon monoxide and copper oxides (or copper metal and oxygen) gives methyl acetate (AcOMe).The reaction was investigated in a pressure reactor in the temperature range of 100 to 300 deg C and pressures of 20 to 150 atm.The oxidative carbonylation of methyl bromide (MeBr) with CO and Cu2O at 270 deg C under a pressure of 130 atm gave 48 mol percent Me2O and 33 mol percent AcOMe.Replacing Cu2O with CuO gave about 40-50percent AcOMe, with 10-20percent Me2O.Using Cu and O2 gave ca. 50percent AcOMe, with 5percent Me2O.In the reaction 5-10percent MeF is also formed due to halogen exchange.The reactivity of the methyl halides shows the decreasing order of MeBr > MeCl > MeF.
- Olah, George A.,Bukala, Jozef
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- Methylation of cyclopentadiene on solid base catalysts with different surface acid-base properties
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The methylation of cyclopentadiene with methanol has been studied over Al2O3 and KOH promoted MgO and unpromoted MgO. The dehydrogenation of methanol to formaldehyde was found to be a key-step in the generation of the active methylating species on these solid bases. The modification with Al2O3 or KOH favors the formation of methylcyclopentadienes and elevates the activity of MgO based on different reasons: introduction of acidic sites for Al2O3/MgO and superbasic effect for KOH/MgO. These catalysts present different deactivation behaviors due to the different surface acid-base properties. The heavy coking of cyclopentadiene on basic sites is responsible for the rapid deactivation of KOH/MgO along the catalytic test at 773 K. However, the coking can be well suppressed at 723 K, and KOH/MgO exhibits the catalytic performance apparently superior to MgO and Al2O3/MgO.
- Lan, Dongxue,Ma, Li,Chun, Yuan,Wu, Chen,Sun, Linbing,Zhu, Jianhua
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- Gas-Phase Chemistry of Trimethyl Phosphite
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The reactions of trimethyl phosphite, (CH3O)3P, with the nucleophiles H2N-, CH3NH-, (CH3)2N-, HO-, H(18)O-, CH3O-, CD3O-, H-, F-, H2P-, CH2=CH-CH2- and (CH3)2C=C(CH3)CH2- were investigated.Products, branching ratios, and reaction rate constants are reported.Reactions generally proceed through an ion-dipole complex -.(CH3O)3P>, to a phosphoranide anion intermediate, -> to displacement of methoxide to form a new ion-dipole complex -.(CH3O)2PZ>.If an additional acidic hydrogen is available on the nucleophile, the major products results from proton abstraction by methoxide: -(CH3O)2PYH> -> (CH3O)2PY- + CH3OH.When the displacement of methoxide from phosphorus is sufficiently endothermic, a competing attack at carbon by the original nucleophile occurs: -(CH3O)3P> -> CH3YH + (CH3O)2PO-.Nucleophiles without an additional acidic hydrogen reacts similarly, but the final reaction products result from (1) SN2 reaction of methoxide, -> -> Z(CH3O)PO- + CH3OCH3, (2) SN2 reaction of the original nucleophile, -(CH3O)3P> -> CH3Z + (CH3O)2PO-, (3) stabilization of the phosphoranide intermediate to give the adduct Z(CH3O)3P-, and (4) expulsion of methoxide from the ion-dipole complex.Reaction mechanisms are discussed in terms of the nature of the nucleophiles, the observed products, and the thermodynamics of the displacement reaction.
- Anderson, David R.,DePuy, Charles H.,Filley, Jonathan,Bierbaum, Veronica M.
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- Methanol carbonylation catalyzed by TiO2-supported gold: An in-situ infrared spectroscopic investigation
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TiO2-supported gold samples prepared by deposition-precipitation were tested as catalysts for methanol carbonylation to give methyl acetate at atmospheric pressure in the presence of methyl iodide as cocatalyst. Infrared (IR) spectroscopy was used to investigate the reactions of methanol, CO and CH3I on the surface of the samples. The results show the formation of methoxy species bonded to Ti4+ sites upon adsorption of methanol on the supported gold samples. Admission of CO to the flow reactor/IR cell led to the formation of gold carbonyls, which reacted with the surface methoxy species only when CH3I was present to give methyl acetate. The data indicate that CH3I is necessary to form gold-acetyl species, which are attacked by neighboring methoxy species to give the carbonylation product. Our results show that the methanol carbonylation catalyzed by TiO2-supported gold in the presence of CH3I occurs by a reaction mechanism that is similar to that occurring on supported Rh catalysts.
- Martinez-Ramirez,Flores-Escamilla,Berumen-Espa?a,Jimenez-Lam,Handy,Cardenas-Galindo,Sarmiento-Lopez, Adan G.,Fierro-Gonzalez
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- Dehydrogenation of Methanol to Formaldehyde over Silicalite
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Formaldehyde is formed by catalytic dehydrogenation of methanol over silicalite containing sodium ions at 670-820 K.
- Matsumura, Yasuyuki,Hashimoto, Keiji,Yoshida, Satohiro
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- Catalytic properties of zirconium phosphate and double phosphates of zirconium and alkali metals with a NaZr2(PO4)3 structure
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Zirconium orthophosphate Zr3(PO4)4 and double phosphates of zirconium and alkali metals AZr2(PO 4)3 (A = Na, K, Rb, Cs) with a NaZr2(PO 4)3 structure were synthesized and characterized by X-ray diffraction and electron microprobe analyses and capillary condensation of nitrogen. The catalytic properties of the phosphates in the dehydration of methanol were studied. Pleiades Publishing, Inc., 2006.
- Sukhanov,Ermilova,Orekhova,Pet'kov,Tereshchenko
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- SAPO-34 synthesized with n-butylamine as a template and its catalytic application in the methanol amination reaction
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SAPO-34 was synthesized with n-butylamine (BA) as a template for the first time. Crystallization temperature and initial Si amount were important factors leading to successful syntheses. Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures, though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature. Higher temperature (240 °C) can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation. The crystallization processes at 200 and 240 °C were investigated and compared. We used the aminothermal method to synthesize SAPO-34-BA at 240 °C and also found n-propylamine is a suitable template for the synthesis of SAPO-34. The SAPO-34-BA products were characterized by many techniques. SAPO-34-BA has good thermal stability, crystallinity and porosity. BA remained intact in the crystals with ～1.8 BA molecule per chabazite cage. The catalytic performance of SAPO-34 was tested in the methanol amination reaction, which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated, suggesting that this material is a good candidate for the synthesis of methylamines.
- Qiao, Yuyan,Wu, Pengfei,Xiang, Xiao,Yang, Miao,Wang, Quanyi,Tian, Peng,Liu, Zhongmin
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- Effect of Phosphate Ions on the Surface Chemistry and Microstructure of Amorphous Alumina
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High-surface-area amorphous Al2O3-AlPO4 samples (P/Al ratio: 0-0.17) have been prepared by reductive decomposition of aluminium nitrate in the presence of phosphoric acid.The materials obtained are amorphous up to 1100-1200 K and present "zeolitic-type" m
- Abbattista, Fedele,Delmastro, Alessandro,Gozzelino, Giuseppe,Mazza, Daniele,Vallino, Mario,et al.
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- The room temperature decomposition mechanism of dimethyl methylphosphonate (DMMP) on alumina-supported cerium oxide - Participation of nano-sized cerium oxide domains
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The adsorption and decomposition reactions of dimethyl methylphosphonate (DMMP) on cerium oxide supported on aluminum oxide have been examined at 25?°C. Experiments were carried out that involved dosing the reactive adsorbent with small doses of DMMP, followed by quantitative determination of the decomposition products. The results suggest that the formation reactions of methanol and dimethyl ether are competitive processes involving the same surface intermediate, which is most likely a surface methoxy species. Based on the observed results, it is proposed that the formation of dimethyl ether is due to the combination of two surface methoxy groups, while an important, if not the dominant, reaction producing methanol involves a surface methoxy group interacting with a vapor phase or physisorbed DMMP molecule. The presence of significant amounts of methoxy fragments formed upon DMMP adsorption is supported by results from diffuse reflectance spectroscopy, which also show that those groups are primarily associated with the cerium oxide domains. FT-Raman spectroscopy shows that the most active cerium oxide domains are highly dispersed two-dimensional domains or very small (a relatively narrow particle size distribution of cerium oxide crystallites on the alumina support surface from the sample preparation method. The alumina-supported cerium oxide reactive adsorbents developed as part of this study are the most active that have been reported in the literature for ambient temperature applications, decomposing approximately 775 ??mol of DMMP per gram of adsorbent at 25?°C, and strongly or irreversibly adsorbing an additional 400 ??mol, for a total capacity at room temperature of 1.1-1.2 mmol of DMMP per gram.
- Mitchell, Mark B.,Sheinker, Viktor N.,Cox Jr., Woodrow W.,Gatimu, Enid N.,Tesfamichael, Aron B.
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- Highly selective formation of propylene from methanol over high-silica EU-1 zeolite catalyst
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High-silica EU-1 zeolite (SiO2/Al2O3 = ~ 400) was tested in methanol to propylene (MTP) reaction and was found to be a very efficient catalyst. In comparison with the other three high-silica zeolites, i.e. ZSM-48, ZSM-5, and beta zeolites, a higher propylene selectivity (52%) and remarkably high propylene/ethylene (P/E) ratio (15) were obtained under the operating conditions of T = 450°C, P = 0.1 MPa, and WHSV = 1.5 h- 1. Besides, a substantially low amount of C5 + hydrocarbons, especially aromatics is another prominent feature of the product distribution over high-silica EU-1 catalyst. Crown Copyright
- Hu, Si,Gong, Yanjun,Xu, Qinghu,Liu, Xiaoling,Zhang, Qing,Zhang, Lanlan,Dou, Tao
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- Discovery of Superior Cu-GaOx-HoOy Catalysts for the Reduction of Carbon Dioxide to Methanol at Atmospheric Pressure
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Catalytic conversion of carbon dioxide to liquid fuels and basic chemicals by using solar-derived hydrogen at, or near, ambient pressure is a highly desirable goal in heterogeneous catalysis. If realized, this technology could lead to a more sustainable society together with decentralized power generation. A novel class of holmium-containing multi-metal oxide Cu catalysts, discovered through the application of high-throughput methods, is reported. In particular, ternary systems of Cu-GaOx-HoOy>Cu-CeOx-HoOy>Cu-LaOx-HoOy supported on γ-Al2O3 exhibited superior methanol production (10×) with less CO formation than previously reported catalysts at 1 atm pressure. Holmium was shown to be highly dispersed as few-atom clusters, suggesting that the formation of trimetallic sites could be the key for the promotion of methanol synthesis by Ho.
- Zohour, Bahman,Yilgor, Iskender,Gulgun, Mehmet A.,Birer, Ozgur,Unal, Ugur,Leidholm, Craig,Senkan, Selim
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- Selective Methanol Carbonylation to Acetic Acid on Heterogeneous Atomically Dispersed ReO4/SiO2Catalysts
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Methanol carbonylation to acetic acid (AA) is a large-scale commodity chemical production process that requires homogeneous liquid-phase organometallic catalysts with corrosive halide-based cocatalysts to achieve high selectivity and activity. Here, we demonstrate a heterogeneous catalyst based on atomically dispersed rhenium (ReO4) active sites on an inert support (SiO2) for the halide-free, gas phase carbonylation of methanol to AA. Atomically dispersed ReO4 species and nanometer sized ReOx clusters were deposited on a high surface area (700 m2/g) inert SiO2 using triethanolamine as a dispersion promoter and characterized using aberration corrected scanning transmission electron microscopy (AC-STEM), UV-vis spectroscopy, and X-ray absorption spectroscopy (XAS). Reactivity measurements at atmospheric pressure with 30 mbar of methanol and CO (1:1 molar ratio) showed that bulk Re2O7 and ReOx clusters on SiO2 (formed at >10 wt %) were selective for dimethyl ether formation, while atomically dispersed ReO4 on SiO2 (formed at 93% selectivity to AA with single pass conversion >60%. Kinetic analysis, in situ FTIR, and in situ XAS measurements suggest that the AA formation mechanism involves methanol activation on ReO4, followed by CO insertion into the terminal methyl species. Further, the introduction of 0.2 wt % of atomically dispersed Rh to 10 wt % atomically dispersed ReO4 on SiO2 resulted in >96% selectivity toward AA production at volumetric reaction rates comparable to homogeneous processes. This work introduces a new class of promising heterogeneous catalysts based on atomically dispersed ReO4 on inert supports for alcohol carbonylation.
- Bare, Simon R.,Christopher, Phillip,Finzel, Jordan,Hoffman, Adam S.,Pan, Xiaoqing,Qi, Ji,Robatjazi, Hossein,Xu, Mingjie
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- Preparation and characterization of nonmetal promoter modified CuZnAl catalysts for higher alcohol from synthesis gas through complete liquid phase method
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A complete liquid phase technology and a function regulator were applied to prepare CuZnAl catalysts for higher alcohol synthesis. Characterizations showed that the introduction of the function regulator can change the reduction ability of copper oxides and the surface basicity of catalysts. Activity tests indicated that the selectivity of higher alcohol is high when considerable medium-strong basicity and the synergistic eects of copper ion and metal copper exist on the catalytic surface. The optimized modified CuZnAl catalyst without any metal additives provides a CO conversion of 28.9%, C2+OH selectivity of up to 42.8%, and hydrocarbon selectivity of 2.5%, with a total alcohol selectivity of 67.4% under the reaction conditions of 5.0 MPa, 250 C, H2/CO = 1, and a gas hourly space velocity of 360 mL/g cat h. TUeBITAK.
- Yu, Shi-Rui,Wang, Xiao-Dong,Huang, Wei
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- Direct dehydrogenation of methanol to anhydrous formaldehyde over Ag2O/γ-Al2O3 nanocatalysts at relatively low temperature
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A series of Ag2O/γ-Al2O3 nanocatalysts for direct dehydrogenation of methanol with various extents of Ag2O loading (0.5–15?wt%) were prepared by the wet impregnation method. The catalysts were characterized by XRD, TEM and N2 sorption. The catalysts were tested for direct dehydrogenation of methanol in a fixed-bed reactor at a relatively low temperature, 330?°C, using N2 as a carrier gas. The obtained results revealed that pure γ-Al2O3 exhibits quite poor selectivity toward formaldehyde (FA) formation (≈28%). On the other hand, the addition of Ag2O improves the catalytic activity of γ-Al2O3 where the catalyst with 10?wt% Ag2O exhibits 100% conversion of methanol with 100% yield of FA. Moreover, the catalyst with 1?wt% Ag2O achieved similar results at the reaction temperature of 370?°C.
- Said, Abd El-Aziz A.,El-Aal, Mohamed Abd
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- Superacid-Catalyzed Carbonylation of Methane, Methyl Halides, Methyl Alcohol, and Dimethyl Ether to Methyl Acetate and Acetic Acid
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Superacid-catalyzed (BF3, BF3-H2O, HF-BF3, and CF3SO3H) carbonylation of methane and its substituted derivatives (particularly, methyl alcohol and dimethyl ether) gave acetic acid and methyl acetate.HF-BF3 was found to be the most effective catalyst, giving nearly complete conversion of methyl alcohol or dimethyl ether.CF3SO3H led to lower yields and also to the formation of methyl trifluoromethanesulfonate.Possible reaction pathways and mechanisms are discussed on the basis of experimental results.Contrasted with Rh-catalyzed carbonylation of methyl alcohol, the superacid-catalyzed reaction does not necessitate expensive catalyst and conditions necessary with sensitive organometallic catalyst system.
- Bagno, Alessandro,Bukala, Jozef,Olah, George A.
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- Oxidation of methane to methanol on the surface of FeZSM-5 zeolite
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In our previous work using FeZSM-5 zeolite with increased concentration of α-sites (100 μmol/g), the oxidation of methane by α-oxygen predeposited from nitrous oxide was studied at room temperature. The reaction proceeded by hydrogen abstraction mechanism yielding methoxy and hydroxy groups bound to α-sites. The present work conducted with the same zeolite is devoted to methane oxidation by N2O in the process of α-oxygen deposition at 160°. Under these conditions, the reaction was shown to proceed at a stoichiometric ratio N4:N2O = 1:1 yielding directly methanol. Spillover of methanol from α-sites liberates them for further events of α-oxygen deposition, thus converting the reaction to a "quasicatalytic" mode that runs up to turnover number exceeding 3 with no product desorption into the gas phase. A part of methanol is converted to dimethyl ether, traces of acetaldehyde, and some amount of non-extractable products. Mechanism of the reaction is discussed.
- Starokon, Eugeny V.,Parfenov, Mikhail V.,Arzumanov, Sergey S.,Pirutko, Larisa V.,Stepanov, Alexander G.,Panov, Gennady I.
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- 13C and 15N solid-state MAS NMR study of the conversion of methanol and ammonia over H-RHO and H-SAPO-34 microporous catalysts
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13C and 15N MAS NMR have been used to study the conversion of methanol and ammonia over H-SAPO-34 and H-RHO using sealed glass ampoules as microreactors under static batch conditions. The product peaks were well resolved in the 13C NMR spectra whereas the 15N NMR spectra gave only a single broad peak making it impossible to follow the reaction by observing this nucleus. Both catalysts give the tetramethyammonium cation whereas only zeolite H-RHO produces the monomethylammonium cation.
- Thursfield, Alan,Anderson, Michael W.,Dwyer, John,Hutchings, Graham J.,Lee, Darren
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- First application of supported ionic liquid phase (SILP) catalysis for continuous methanol carbonylation
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A solid, silica-supported ionic liquid phase (SILP) rhodium iodide Monsanto-type catalyst system, [BMIM][Rh(CO)2I2]-[BMIM]I- SiO2, exhibits excellent activity and selectivity towards acetyl products in fixed-bed, continuous gas-phase methanol carbonylation. The Royal Society of Chemistry 2006.
- Riisager, Anders,Jorgensen, Betina,Wasserscheid, Peter,Fehrmann, Rasmus
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- Onium Ylide Chemistry. 3. Evidence for Competing Oxonium Ylide Formation with C-H Insertion in Meerwein's Reaction of Methylene and Methylene-d2 with Dialkyl Ethers
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Meerwein's reaction of singlet methylene, produced by photolysis of diazomethane, with dialkyl ethers has been reinvestigated on the basis of reactions using CD2N2.In competition with methylene insertion into the various C-H bonds, about 10percent of methyl alkyl ether and small amounts of dimethyl ether formation are also observed.This indicates evidence for competing attack of methylene on oxygen leading to the corresponding intermediate methylenedialkyloxonium ylides which are immediately protonated by methyl alkohol (or water)impurity present in the reaction medium togive the corresponding methyldialkyloxonium ions.Dealkylative cleavage of the latter gives the observed methyl alkyl ethers.By the use of deuterium-labeled diazomethane CD2N2 it has been shown that ethylene and propylene formed under the reaction conditions are coming predominantly from diazomethane itself and not via intramolecular β-elimination of the oxonium ylides.
- Olah, George A.,Doggweiler, Hans,Felberg, Jeff D.
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- Kinetics of liquid-phase noncatalytic methanol hydrochlorination in hydrochloric acid
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The kinetics of the liquid-phase noncatalytic hydrochlorination of methanol in hydrochloric acid is reported. The methyl chloride formation rate depends on the methanol concentration in hydrochloric acid and on the partial pressure of hydrogen chloride over hydrochloric acid. The activation energy of the reaction is 113 kJ/mol. The rate of the side process of dimethyl ether evolution is directly proportional to the methanol concentration and is inversely proportional to the partial pressure of hydrogen chloride over hydrochloric acid. The activation energy of the side reaction is about 33 kJ/mol. The results of the industrial implementation of methyl chloride synthesis from methanol and hydrochloric acid are in satisfactory agreement with the laboratory data.
- Rozanov,Treger
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- Electrochemically assisted synthesis of fuels by CO2 hydrogenation over Fe in a bench scale solid electrolyte membrane reactor
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The electrochemically assisted synthesis of fuels by CO2 hydrogenation was studied over a cheap, widespread and non-precious Fe catalyst in a bench scale oxygen ion conducting membrane (YSZ) reactor. The studies were performed under conditions representative of potential practical application i.e., under atmospheric pressure, at relatively low temperatures and high gas flow rates, with varying H2/CO2 ratios and using gas compositions typical for postcombustion CO2 capture exit streams and easily scalable catalyst-electrode configurations. The Fe-TiO2 catalyst film was deposited by "dip-coating" and characterised both after pre-reduction and after testing. CO2 conversion and selectivities to CH3OH and C2H6O can be enhanced up to 4, 50 and 1.7 times, respectively, by electrochemically controlled migration of O2- promoting ions to or from the catalyst surface. The optimum temperature for the process was 325°C. Lower gas flow rates favoured the synthesis of CH3OH and C2H6O. CO2 conversion and selectivities to CH3OH and C2H6O showed a maximum for a stoichiometric H2/CO2 ratio of 3. Formation of C3H6 and CO is strongly favoured for a H2/CO2 ratio of 4 and 2, respectively, as a result of the increased and decreased hydrogen availability in the reaction system.
- Ruiz, Esperanza,Martínez, Pedro J.,Morales, ángel,San Vicente, Gema,De Diego, Gonzalo,Sánchez, José María
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- Support Effect of Zinc Oxide Catalyst on Synthesis of Methanol from CO2 and H2
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The synthesis of methanol from CO2 + H2 was carried out at 340-400 deg C under total pressure of 10 atm over ZnO supported MgO, Al2O3, SiO2, TiO2, ZrO2, and Nb2O5.The ZnO/ZrO2 catalyst show high activity and selectivity for methanol formation.The hydrogenation of CO2 was more selective for methanol synthesis than that of CO.
- Inoue, Takashi,Iizuka, Tokio,Tanabe, Kozo
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- Support Effects in the Formation of Methanol from Carbon Dioxide and Hydrogen over Rhenium Catalysts
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In the hydrogenation of carbon dioxide over supported Re catalysts the selectivity for methanol formation was high over Re-ZrO2 and Re-Nb2O5 under moderate conditions (10 atm, 160-220 deg C).
- Iizuka, Tokio,Kojima, Masanao,Tanabe, Kozo
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- A crystalline catalyst based on a porous metal-organic framework and 12-tungstosilicic acid: Particle size control by hydrothermal synthesis for the formation of dimethyl ether
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The strategy for obtaining a crystalline catalyst based on a porous copper-based metal-organic framework and 12-tungstosilicic acid with different particle sizes is reported. Through the control of hydrothermal synthesis and some simple treatments, catalyst samples with average particle diameters of 23, 105, and 450-μm, respectively, were prepared. This crystal catalyst has both the Bronsted acidity of 12-tungstosilicic acid and the Lewis acidity of the copper-based metal-organic framework, and has high density of accessible acid sites. Its catalytic activity was fully assessed in the dehydration of methanol to dimethyl ether. The effect of particle size on the catalytic activity of catalyst was studied, in order to select the particle size appropriate for avoiding the diffusion limitation in heterogeneous gas-phase catalysis. In the selective dehydration of methanol to dimethyl ether, this catalyst exhibited higher catalytic activity than the copper-based metal-organic framework, γ-alumina, and γ-alumina-supported 12-tungstosilicic acid catalysts. It showed high catalytic performances, even at higher space velocity or in the presence of excess water. In addition, the catalyst was also preliminarily assessed in the formation of ethyl acetate from acetic acid and ethylene. It also exhibited a high activity which was comparable with that of silica-supported 12-tungstosilicic acid catalyst. Copyright
- Liang, Da-Dong,Liu, Shu-Xia,Ma, Feng-Ji,Wei, Feng,Chen, Ya-Guang
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- Intrinsic Kinetics of Dimethyl Ether Synthesis from Plasma Activation of CO2 Hydrogenation over Cu–Fe–Ce/HZSM-5
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CO2 is activated in a plasma reactor followed by hydrogenation over a Cu–Fe–Ce/HZSM-5 catalyst, and the intrinsic kinetics of the plasma catalytic process are studied. Compared with CO2 hydrogenation using Cu–Fe–Ce/HZSM-5 alone, the CO2 conversion and the dimethyl ether selectivity for the plasma catalytic process are increased by 16.3 %, and 10.1 %, respectively, indicating that the CO2 was activated by the plasma to promote hydrogenation. A study of the intrinsic kinetics shows that the activation energies of methanol formation, the reverse water–gas shift reaction, and methanol dehydration to dimethyl ether are 149.34, 75.47, and 73.18 kJ mol?1, respectively, which are lower than if Cu–Fe–Ce/HZSM-5 is used without plasma, indicating that the activation of CO2 in the plasma reduces the activation energy of the hydrogenation reaction and improves the yield of dimethyl ether.
- Su, Tongming,Zhou, Xinhui,Qin, Zuzeng,Ji, Hongbing
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- Mechanisms of the deactivation of SAPO-34 materials with different crystal sizes applied as MTO catalysts
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SAPO-34 materials with comparable Bronsted acid site density but different crystal sizes were applied as methanol-to-olefin (MTO) catalysts to elucidate the effect of the crystal size on their deactivation behaviors. 13C HPDEC MAS NMR, FTIR, and UV/vis spectroscopy were employed to monitor the formation and nature of organic deposits, and the densities of accessible Bronsted acid sites and active hydrocarbon-pool species were studied as a function of time-on-stream (TOS) by 1H MAS NMR spectroscopy. The above-mentioned spectroscopic methods gave a very complex picture of the deactivation mechanism consisting of a number of different steps. The most important of these steps is the formation of alkyl aromatics with large alkyl chains improving at first the olefin selectivity, but hindering the reactant diffusion after longer TOS. The hindered reactant diffusion leads to a surplus of retarded olefinic reaction products in the SAPO-34 pores accompanied by their oligomerization and the formation of polycyclic aromatics. Finally, these polycyclic aromatics are responsible for a total blocking of the SAPO-34 pores, making all catalytically active sites inside the pores nonaccessible for further reactants.
- Dai, Weili,Wu, Guangjun,Li, Landong,Guan, Naijia,Hunger, Michael
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- Catalytic performances of binder-free ZSM-5 catalysts for dehydration of crude methanol to dimethyl ether
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A series of binder-free ZSM-5 catalysts and a binder-containing catalyst were prepared and characterized with X-ray diffraction (XRD), X-ray fluorescence (XRF), 27Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR), N2 sorption and ammonia temperature-programmed deposition (TPD) methods. The catalytic activity and selectivity in the dehydration of crude methanol to dimethyl ether (DME) were evaluated in a fixed-bed reactor for the catalysts. The outstanding structural characters such as high zeolite contents, sufficiently open channels and richness in mesopores have been proved on these binder-free catalysts. The influence of the solid-acidity, which is closely related to the framework silica alumina ratio (SAR) of the catalysts, on the catalytic properties has been discussed. A binder-free catalyst with a better potential in application has been selected for its high activity and selectivity, long life-time and non-sensitivity to water contents in the feed. The reason for its excellent performance of the catalyst was discussed.
- Wang, Jing,Cheng, Xiaowei,Guo, Juan,Chen, Xiaocheng,He, Heyong,Long, Yingcai
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- Structure and Catalytic Activity of Alumina-Supported Pt-Co Bimetallic Catalysts. 2. Chemisorption and Catalytic Reactions
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A series od Pt1-xCox/Al2O3 bimetallic catalysts have been characterized by temperature-programmed reduction (TPR), chemisorption of hydrogen and CO, deuterium exchange using both methanol and methane, and activity for the CO/H2 reaction.A Pt-assisted reduction mechanism over the entire range of composition was established by the TPR studies as well as by the chemisorption results.An enhanced metallic dispersion for the Pt-rich catalyst and formation of bimetallic particles on the Co-rich side was also indicated.In the CO hydrogenation over the Pt-rich catalysts the predominant products are methanol and dimethyl ether whereas on the Co-rich samples hydrocarbons and higher alcohols are produced.The mechanisms of deuterium exchange with methane and methanol are significantly different, the former being catalyzed solely by metallic sites while the latter utilizes both oxide and metallic sites for stepwise and multiple exchange, respectively.On the basis of the XPS data (preceding article) as well as the chemisorption results reported here, a surface model is introduced for interpretation of the catalytic results.
- Guczi, Lazlo,Hoffer, Tamas,Zsoldos, Zoltan,Zyade, Souad,Maire, Gilbert,Garin, Francois
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- Artifical Layer Surface of Periodic Cu-TiO2 for Catalytic Decomposition of Methanol
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Periodic thin-layer composites of Cu and TiO2 were fabricated by alternating depositions in a form of regularly distributed small spots (150 μm in diameter) in order to obtain artifically modulated catalytically active surfaces.The periodic surfaces perpendicular to the deposition direction were applied to the catalytic decomposition of CH3OH.The thickness of a Cu unit layer was changed in the range 3-10 nm, while that of the oxide support was kept at 10 nm with the total number of accumulated layers being 45.The periodic modulations of as-deposited and heat-treated composites were characterized by means of small-angle X-ray diffraction, Auger electron spectroscopy, secondary ion mass spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope observations.It was shown that the artifical layer structures were stable upon heat treatment in vacuo and in a H2 atmosphere at high temperatures.In catalytic reaction on the Cu phases at low pressures, an interesting feature was the appearance of a maximum in the selectivity of H2CO formation at a medium thickness of the Cu layer.The effects of the periodic structures are discussed.
- Inoue, Yasunobu,Sasaki, Takanori,Sato, Kazunori,Ohno, Masaaki
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- ALKYL TRANSFER REACTIONS BETWEEN PROTONATED ALCOHOLS AND ETHERS. GAS-PHASE ALKYLATION OF FORMALDEHYDE
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Alkyl-transfer reactions involving protonated alcohols and ethers, of the general type R2OR'+ + R''2O -> R""OR'+ + R2O, may be classified according to the degree of alkylation, i.e., the total number n of alkyl groups in the system.For systems containing two alkyl groups, the reaction is alkyl transfer between protonated and neutral alcohols, ROH2+ + ROH -> R2OH+ + H2O, and we measured rate constants for R=Me, Et, i-Pr, and t-Bu.The rate constants are (0.6-1.5) x 1E-10 cm3s-1 when R is a normal alkane and (6 +/- 1) x 1E-10 when R=i-Pr and t-Bu.The larger rate constants in the latter may be due to a lowered barrier for the initial partial R+-OH2 bond dissociation.For reaction systems containing three alkyl groups, i.e., the reactions of protonated ethers R2OH+ with alcohols R'OH, the possible channels are alkyl transfer from the alcohol, yielding R2OR'+, or alkyl transfer from the ether, yielding ROR'H+.Both processes are observed in (CH3)2OH+ + C2D5OH which yields both (CH3)2OC2D5H+ and CH3OC2D5H+.For systems containing four alkyl groups an example is the reaction(CH3)2OH+ + (CH3)2O -> (CH3)3O+ + CH3OH, which is a slow reaction with k3s-1.Finally, for the highest possible degree of alkylation, n=5, an example is methyl transfer in (CH3)OCD3+ + (CH3)2O -> (CH3)2OCH3+ + CH3OCD3 which is a very slow reaction, observed only above 500K.The rate constants for alcohols show negligible temperature dependence between 300 and 670 K, but in the most highly alkylated system the rate increases strongly with temperature, and an activation energy of 15 kcal-1 is observed.The results show that alkyl transfer occurs in systems with all possible degrees of alkylation, but the rates tend to decrease with increasing alkylation.In addition to saturated systems, alkyl transfer is also observed with unsaturated ions or neutrals.Examples are alkyl transfer between unsaturated oxocarbonium ions C2H5O+ and methanol and ethanol and between protonated alcohols and CH2O.These reactions have rate constants of (1-4) x 1E-11 cm3s-1.Depending on the temperature coefficients, the alkylation of formaldehyde may be important in astrochemical synthesis.
- Karoas, Zeev,Meot-Ner (Mautner), Michael
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- Synthesis, textural and catalytic properties of nanosized Fe 2O3/MgO system
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FeMgO system was prepared by three different methods. The samples were nominated as FeMgOIM, FeMgOCo and FeMgOHY due to preparation by impregnation, co-precipitation and hydrothermal, respectively. The catalysts were characterized by TGA, XRD, FTIR, EPR, SBET and TEM techniques. The catalytic properties of these samples were investigated by using H2O2 decomposition at (25-35 C) and partial oxidation of methanol at (300-400 C). FeMgOHY sample showed the highest catalytic activity toward H2O2 decomposition. FeMgOCo sample showed the highest catalytic activity toward partial oxidation of methanol. The results showed the sensitivity of H2O 2 decomposition reaction to the surface concentration of active species. While partial oxidation of methanol is sensitive to surface texture, solids interaction between active phase and support. All catalysts are highly selective to formaldehyde at reaction temperature 300 C. FeMgOCo and FeMgOIM catalysts showed high catalytic activity and stability toward partial oxidation of methanol with reusing.
- El-Molla, Sahar A.,Mahmoud, Hala R.
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- Dimethyl ether synthesis process exploiting CO-rich gas
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The present invention relates to a converter gas (Lintz-Donawiaz convert Gas) that is an excess of carbon monoxide-containing gas such as iron-iron enriched gas. Dimethyl ether using LDG). dimethyl ether. DME) A synthesis process. Is a process for producing dimethyl ether, which is a high-value product with high selectivity, utilizing whole gas as a source gas.
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Paragraph 0061-0096
(2021/06/09)
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- CATALYSTS FOR SELECTIVE OXIDATION OF METHANOL TO DIMETHOXYMETHANE AND RELATED METHODS
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Embodiments include catalyst compositions and methods of synthesizing catalyst compositions for the selective oxidation of methanol to dimethoxymethane, as well as methods of selective oxidation of methanol to dimethoxymethane using catalyst compositions. The catalyst composition can comprise vanadium oxide and a mixed metal oxide, wherein the vanadium oxide is supported on the mixed metal oxide and wherein the mixed metal oxide includes a redox component and an acid component. The method of selective oxidation of methanol to dimethoxymethane can comprise at least the following step: contacting methanol with a catalyst composition in the presence of an oxidizing agent to produce dimethoxymethane.
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Paragraph 0074-0078
(2021/10/02)
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- Synthesis of SZR framework type molecular sieves
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A method is provided for synthesizing molecular sieves of SZR framework type using 1,2,3-trimethylimidazolium cations as a structure directing agent and alumina-coated silica as a combined source of silicon and aluminum.
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Page/Page column 6-7
(2021/11/13)
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- METHOD FOR DIRECTLY PREPARING DIMETHYL ETHER BY SYNTHESIS GAS
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Provided is a method for directly preparing dimethyl ether by synthesis gas, the method comprises: the synthesis gas is passed through a reaction zone carrying a catalyst, and reacted under the reaction conditions sufficient to convert at least a portion of the raw materials to obtain the reaction effluent comprising dimethyl ether; and the dimethyl ether is separated from the reaction effluent, wherein the catalyst is zinc aluminum spinel oxide. In the present invention, only one zinc aluminum spinel oxide catalyst is used, which can make the synthesis gas to highly selectively form dimethyl ether, the catalyst has good stability and can be regenerated. The method of the present invention realizes the production of dimethyl ether in one step by the synthesis gas, and reduces the large energy consumption problem caused by step-by-step production.
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Paragraph 0040; 0041; 0044
(2021/08/13)
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- PROCESS FOR SYNTHESIS OF DIMETHYL ETHER
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The present invention depicts a method for one pot synthesis of dimethyl ether from syngas in a simple and economical manner. The process (500A, 500B, 600) has advantages of reducing the requirement of refrigeration and at the same time producing a ready to use product. The process (500A, 500B, 600) includes the steps of separating carbon dioxide from a first stream (512, 612) comprising syngas to produce a second stream (522, 622), reacting the second stream (522, 622) in the presence of a catalyst to produce a third stream (532, 632), cooling the third stream (532, 632) to a temperature in a range from 10o C to 40o C to produce a fourth stream (542, 642), and washing and conducting a phase separation of the fourth stream (542, 642) to produce a product comprising at least 10% by volume of dimethyl ether.
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Page/Page column 0009; 0019
(2021/09/04)
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- Investigation on the promotional role of Ga2O3on the CuO-ZnO/HZSM-5 catalyst for CO2hydrogenation
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Dimethyl ether (DME) can be directly synthesized from carbon dioxide and hydrogen by mixing methanol synthesis catalysts and methanol dehydration catalysts. The activity and selectivity of the catalyst can be greatly affected by the promoter; herein, we presented a series of CuO-ZnO-Ga2O3/HZSM-5 hybrid catalysts, which were prepared by the coprecipitation method. The effect of the Ga2O3 content on the structure and performance of the Ga-promoted Cu-ZnO/HZSM-5 based catalysts was thoroughly investigated. The results showed that the addition of Ga2O3 significantly increased specific surface areas and Cu areas, decreased the size of Cu particles, maintained the proportion of Cu+/Cu0 on the surface of the catalyst, and strengthened the metal-support interaction, resulting in high catalytic performance. This journal is
- Du, Jie,Zhang, Yajing,Wang, Kangjun,Ding, Fu,Jia, Songyan,Liu, Guoguo,Tan, Limei
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p. 14426 - 14433
(2021/05/17)
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- METHOD FOR PREPARING ACRYLIC ACID AND METHYL ACRYLATE
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The present invention provides a method for preparing acrylic acid and methyl acrylate. The method comprises passing the feed gas containing dimethoxymethane and carbon monoxide through a solid acid catalyst to generate acrylic acid and methyl acrylate with a high conversion rate and selectivity at a reaction temperature in a range from 180 to 400 and a reaction pressure in a range from 0.1 MPa to 15.0 MPa, the mass space velocity of dimethoxymethane in the feed gas is in a range from 0.05 h?1 to 10.0 h?1, and the volume percentage of dimethoxymethane in the feed gas is in a range from 0.1% to 95%.
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Paragraph 0076-0081
(2021/04/23)
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- On the reaction mechanism of MnOx/SAPO-34 bifunctional catalysts for the conversion of syngas to light olefins
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MnOx/SAPO-34 bifunctional catalysts are efficient for the conversion of syngas to light olefins. However, the reaction mechanism is still debated in particular the nature of the intermediate formed on MnOx(ketenevs.methanol). In this study, it was evidenced from catalytic data andin situDRIFT measurements that methanol is a key reaction intermediate produced on MnOxthat synergistically reacts with SAPO-34 to produce light olefins.
- Afanasiev, Pavel,Checa, Ruben,Coudercy, Christophe,L'hospital, Valentin,Le Valant, Anthony,Loridant, Stéphane
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p. 7844 - 7849
(2021/12/27)
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- Role of Ga3+promoter in the direct synthesis of iso-butanolviasyngas over a K-ZnO/ZnCr2O4catalyst
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The direct synthesis of iso-butanol is an important reaction in syngas (composed of CO and H2) conversion. K-ZnO/ZnCr2O4(K-ZnCr) is a commonly used catalyst. Here, Ga3+is used as an effective promoter to boost the efficiency of the catalyst and retard the production of CO2. X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflection spectroscopy and electron microscopy were used to characterize the structural variations with different amounts of Ga3+, the results showed that the particle size of the catalyst decreases with the addition of Ga3+. The temperature-programmed desorption of NH3and CO2, and diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTs) analysis of the CO adsorption revealed that the acidity and basicity were altered owing to the different forms of Ga3+adoption. X-ray photoelectron spectroscopy and density functional theory (DFT) calculations revealed that the formation of Ga clusters that are coordinated on the exposed surfaces of ZnCr2O4, and undergo a tetra-coordinated Ga3+exchange with one of the Zn in ZnCr2O4(ZG) and ZnGa2O4, probably depends on the amount of Ga added. The structural evolution of the Ga3+promoted K-ZnO/ZnCr2O4catalysts can be described as follows: (i) the main forms are ZG and Ga coordinated ZnCr2O4, in which the amount of Ga3+is below 1.10 wt%; and (ii) the Ga3+containing compound is gradually changed from ZG to ZnGa2O4and the amount of gallium clusters increased when the amount of Ga3+was higher than 1.10 wt%. The catalytic performance evaluation results show that K-Ga1.10ZnCr exhibits the highest space time yield and selectivity of alcohols, in which the three compounds play different roles in syngas conversion: ZG is the main active site that boosts the efficiency of the catalysts, owing to the intensified CO adsorption and decreased activation energy of CHO formation through CO hydrogenation; ZnGa2O4only modifies the surface basicity and acidity on the catalyst, thereby impacting the carbon chain growth after the CO is adsorbed. The effects of Ga coordinated with ZnCr2O4shows little impact on the CO adsorption owing to the weak electron donating effects of Ga.
- Zhang, Tao,Zeng, Chunyang,Wu, Yingquan,Gong, Nana,Yang, Jiaqian,Yang, Guohui,Tsubaki, Noritatsu,Tan, Yisheng
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p. 1077 - 1088
(2021/02/26)
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- Ni-MoOx bifunctional catalyst on SiO2 for vapor halide-free methanol carbonylation: Insight into synergistic catalysis between Ni and MoOx
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A promising Ni-MoOx bifunctional catalyst for halide-free methanol carbonylation is developed by H2-reduction of NiO-MoO3/SiO2 obtained via facile impregnation method. Catalyst performance is strongly dependent on the calcination/reduction temperature. Over the preferable NiMo-350-600/SiO2 catalyst obtained by calcining at 350 °C and subsequently reducing at 600 °C, a methanol conversion of 4.2 % and acetyls space-time yield of 1.37 mol kgcat?1 h?1 are achieved with 22.1 % selectivity to acetyls at 290 °C and 3 MPa. Co-existence of Ni0 and MoOx (especially MoO2) markedly decreases formation of dimethyl ether (DME) and reversely increases acetyls formation, in nature, due to the catalyst acidity modulation and the partial electron transfer from Ni0 to MoOx that tunes the CO adsorption strength on Ni0 sites. MoO3 and NiMoO4 are both favorable for formation of acetyls and DME whereas the latter mainly accounts for DME formation. MoNi4 alone favors methyl formate formation while together with MoO2 enhancing DME production.
- Liu, Ye,Lu, Yong,Nie, Qiang,Shen, Mengchen,Zhao, Guofeng
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- Transition Metal-Free Direct Hydrogenation of Esters via a Frustrated Lewis Pair
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"Frustrated Lewis pairs"(FLPs) continue to exhibit unique reactivity for the reduction of organic substrates, yet to date, the catalytic hydrogenation of an ester functionality has not been demonstrated. Here, we report that iPr3SnNTf2 (1-NTf2; Tf = SO2CF3) is a more potent Lewis acid than the previously studied iPr3SnOTf; in an FLP with 2,4,6-collidine/2,6-lutidine (col/lut), this translates to faster H2 activation and the catalytic hydrogenolysis of an ester bond by a main-group compound, furnishing alcohol and ether (minor) products. The reaction outcome is sensitive to the steric and electronic properties of the substrate; CF3CO2Et and simple formates (HCO2Me and HCO2Et) are catalytically reduced, whereas related esters CF3CO2nBu and CH3CO2Et show only stoichiometric reactivity. A computational case study on the hydrogenation of CF3CO2Et and CH3CO2Et reveals that both share a common mechanistic pathway; however, key differences in the energies of a Sn-acetal intermediate and transition states emerge, favoring CF3CO2Et reduction. The alcohol products reversibly inhibit 1-NTf2/lut via formation of resting-state species 1-OR/[1·(1-OR)]+[NTf2]- however, the extra energy required to regenerate 1-NTf2/lut exacerbates the unfavorable reduction energy profile for CH3CO2Et, ultimately preventing turnover. These findings will assist the design of future main-group catalysts for ester hydrogenation, with improved performance.
- Sapsford, Joshua S.,Csókás, Dániel,Turnell-Ritson, Roland C.,Parkin, Liam A.,Crawford, Andrew D.,Pápai, Imre,Ashley, Andrew E.
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p. 9143 - 9150
(2021/07/31)
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- Method for synthesizing 1, 3-dihydric alcohol by using olefin and methanol as raw materials
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The invention discloses a method for preparing 1, 3-dihydric alcohol by taking olefin and methanol as raw materials through one-step reaction and a catalyst for the method. The method comprises the following steps: 1) adding a catalyst into a reactor, heating and reducing in a hydrogen-nitrogen mixed atmosphere, then cooling to 60-180 DEG C, and keeping the pressure in the reactor to be 0.5-8 MPa for reaction; 2) respectively introducing olefin and a methanol aqueous solution into the reactor for reaction, wherein the airspeed is 0.01-10h in terms of methanol; 3) enabling that the reaction product enters a product storage tank after condensation and gas-liquid separation; and 4) carrying out rectification separation on the reaction product obtained in the step 3) to obtain a 1, 3-dihydric alcohol product with the purity of more than 99%. The method provided by the invention has the advantages of low raw material cost, simple steps and continuous production.
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Paragraph 0094-0120
(2021/07/28)
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- Ring-Closing Metathesis of Aliphatic Ethers and Esterification of Terpene Alcohols Catalyzed by Functionalized Biochar
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Functionalized biochars, renewable carbon materials prepared from waste biomass, can catalyze transformations of a range of oxygen-containing substrates via hydrogen-bonding interactions. Good conversions (up to 75.2 %) to different O-heterocycles are obtained from ring-closing C?O/C?O metathesis reactions of different aliphatic ethers under optimized conditions using this heterogeneous, metal-free, and easy separable catalyst. The diversity in the sorts of O-containing feedstocks is further demonstrated by the utilization of functionalized biochar to promote the esterification of terpene alcohols, an important reaction in food and flavor industries. Under the optimized conditions, full conversions to various terpene esters are obtained. Moreover, both of the reactions studied herein are performed under neat conditions, thus increasing the overall sustainability of the process described.
- Kerton, Francesca M.,MacQuarrie, Stephanie L.,Vidal, Juliana L.,Wyper, Olivia M.
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supporting information
p. 6052 - 6056
(2021/12/10)
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- Ethanol as a Binder to Fabricate a Highly-Efficient Capsule-Structured CuO?ZnO?Al2O3@HZSM-5 Catalyst for Direct Production of Dimethyl Ether from Syngas
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This work reports a highly efficient capsule-structured CuO?ZnO?Al2O3@HZSM-5 (CZA@HZSM-5-EtOH) core-shell catalyst for the direct conversion of syngas to dimethyl ether by a facile physical coating method with ethanol as a binder through coating micrometer-sized HZSM-5 shell on the prior-shaped millimeter-sized CZA core, it shows 2.9 times higher CO conversion with the 2.7 times higher turnover frequency and 9.2 times higher dimethyl ether space-time yield of the CZA@HZSM-5-SS catalyst prepared by a similar process but with silica sol as a binder (315.5 vs 34.3 gDME kgcat ?1 h?1). The relationship between the structure and performance was explored by a variety of characterization techniques including X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), ammonia temperature programmed desorption (NH3-TPD), nitrogen adsorption-desorption, H2-temperature-programmed reduction (H2-TPR) and H2-TPR after oxidation of the samples by N2O. CZA@HZSM-5-EtOH can be considered as a highly efficient and practical catalyst for dimethyl ether synthesis from syngas. This work presents a new avenue to design other bifunctional catalysts for the cascade reactions in which the raw materials can be converted into an intermediate over the core and then the as-formed intermediate over the core can be subsequently converted into the final product.
- Guo, Yongle,Zhao, Zhongkui
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p. 999 - 1006
(2020/01/25)
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- Implanting Copper?Zinc Nanoparticles into the Matrix of Mesoporous Alumina as a Highly Selective Bifunctional Catalyst for Direct Synthesis of Dimethyl Ether from Syngas
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Dimethyl ether (DME) is an industrially important intermediate and clean alternative fuel. Thus, developing an efficient bifunctional catalyst for syngas-to-DME is practically important but remains a challenge. In this paper, a copper?zinc implanting into matrix of mesoporous alumina (CuZn@m?Al2O3) catalyst was prepared by introducing the as-prepared Cu?Zn oxalate nanoparticles into the Al(i-OPr)3-containing precursor solution for preparing mesoporous Al2O3 (m-Al2O3) through evaporation-inducing assembly method. The preparation of Cu?Zn oxalate in advance for synthesizing CuZn@m?Al2O3 can intensify the Cu?ZnO interaction, confirmed by XRD and H2-TPR. Thanks to the unique CuZn-implanting closed structure, CuZn@m?Al2O3 shows 89.0 % of higher selectivity with comparable CO conversion (15.5 %) than the previously reported supported-type CuZn catalyst on m-Al2O3 (CuZn/m?Al2O3, 75.2 %) for hydrogenation of syngas to DME. Over the developed CuZn@m?Al2O3 catalyst, 0.16 mmol g?1 cat h?1 of high DME rate can be achieved. CuZn@m?Al2O3 also shows higher methanation resistance (2.7 % CH4) compared to CuZn/m?Al2O3 (6.3 %), ascribed to intensified Cu?Zn interaction owing to the as-formation of Cu?Zn oxalate in advance. Moreover, Both CuZn@m?Al2O3 and CuZn/m?Al2O3 exhibit high stability. The outstanding catalytic performance of CuZn@m?Al2O3 allows it to be a promising catalyst for DME synthesis from syngas.
- Sun, Yingqi,Zhao, Zhongkui
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p. 1276 - 1281
(2020/01/21)
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- Glucose oxidation to formic acid and methyl formate in perfect selectivity
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We report the highly remarkable discovery that glucose oxidation catalysed by polyoxometalates (POMs) in methanolic solution enables formation of formic acid and methyl formate in close to 100percent combined selectivity, thus with only negligible sugar oxidation to CO2. In detail, we report oxidation of a methanolic glucose solution using H8[PV5Mo7O40] (HPA-5) as catalyst at 90 °C and 20 bar O2 pressure. Experiments with 13C-labelled glucose confirm unambiguously that glucose is the only source of the observed formic acid and methyl formate formation under the applied oxidation conditions. Our results demonstrate a very astonishing solvent effect for the POM-catalysed glucose oxidation. In comparison to earlier work, a step-change in product yield and selectivity is achieved by applying an alcoholic reaction medium. The extremely high combined yields of formic acid and methyl formate greatly facilitate product isolation as low-boiling methyl formate (bp = 32 °C) can simply be isolated from the reaction mixture by distillation.
- Albert, Jakob,Bukowski, Anna,Kumpidet, Chiraphat,Maerten, Stephanie,Vo?, Dorothea,Wasserscheid, Peter
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p. 4311 - 4320
(2020/07/14)
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- LAYERED CATALYST LOADING FOR SYNTHESIS GAS CONVERSION
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Systems and methods are provided for conversion of gas phase reactants including CO and H2 to C2+ products using multiple catalysts in a single reactor while reducing or minimizing deactivation of the catalysts. Separate catalysts can be used that correspond to a first catalyst, such as a catalyst for synthesis of methanol from synthesis gas, and a second catalyst, such as a catalyst for conversion of methanol to a desired C2+ product. The separate catalysts can be loaded into the reactor in distinct layers that are separated by spacer layers. The spacer layers can correspond to relatively inert particles, such as silica particles. Optionally, the spacer layer can include an adsorbent, such as boron supported on alumina or boron carbide particles. The adsorbent can be suitable for selective adsorption of the one or more reaction products (such as one or more reaction by-products), to allow for further reduction or minimization of the deactivation of the conversion catalysts.
- -
-
Paragraph 0071-0083
(2020/07/31)
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- Structural Relaxation Enabled by Internal Vacancy Available in a 24-Atom Gold Cluster Reinforces Catalytic Reactivity
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Unveiling the mystery of the contribution of nonsurface or noninterface sites in a catalyst to its catalytic performance remains a great challenge because of the difficulty in capturing precisely structural information (surface plus inner) encoded in the catalyst. This work attempts to elucidate the critical role of the internal vacancy in an atomically precise 24-atom gold cluster in regulating the catalytic performance on the hydrogenation reaction of CO2. The experiment results show that the Au24 cluster with internal vacancy can mitigate sintering and exhibit high catalytic activity under relatively harsh reaction conditions, in contrast to the structurally similar Au25 cluster without internal vacancy. Our computational study suggests that the internal vacancy in Au24 provides the cluster with much more structural flexibility, which may be crucial to resisting the aggregation of the cluster and further postponing the deactivation. The hydrogenation and coupling stages of the reaction intermediates are proposed to explain the potential reaction pathway of CO2 with H2 on the Au24 catalyst with internal vacancy.
- Cai, Xiao,Hu, Weigang,Xu, Shun,Yang, Dan,Chen, Mingyang,Shu, Miao,Si, Rui,Ding, Weiping,Zhu, Yan
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supporting information
p. 4141 - 4153
(2020/03/05)
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- Selective Conversion of CO2 into para-Xylene over a ZnCr2O4-ZSM-5 Catalyst
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An oxide-zeolite (ZnCr2O4-ZSM-5) catalyst for directly converting CO2 to aromatics was designed and developed. It showed high PX/X (the C-mol ratio of p-xylene to all xylene) and PX/aromatics (the C-mol ratio of p-xylene to aromatics) ratios, which reached 97.3 and 63.9 %, respectively.
- Gao, Weizhe,Guo, Lisheng,Cui, Yu,Yang, Guohui,He, Yingluo,Zeng, Chunyang,Taguchi, Akira,Abe, Takayuki,Ma, Qingxiang,Yoneyama, Yoshiharu,Tsubaki, Noritatsu
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p. 6541 - 6545
(2020/11/30)
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- Excellent prospects in methyl methoxyacetate synthesis with a highly active and reusable sulfonic acid resin catalyst
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Methyl methoxyacetate (MMAc) is a significant chemical product and can be applied as a gasoline and diesel fuel additive. This study aimed to achieve the industrial production of MMAc via dimethoxymethane (DMM) carbonylation. The effects of industrial DMM sources, reaction temperature, water content, pretreatment temperature, reaction pressure and time, the ratio of CO to DMM and recycle times were systematically investigated without any solvent. The conversion of DMM was 99.98% with 50.66% selectivity of MMAc at 393 K, 6.0 MPa reaction pressure, with the ratio of CO to DMM of only 1.97/1. When water was extracted from the DMM reactant, the MMAc selectivity significantly rose to 68.83%. This resin catalyst was reused for more than nineteen times in a slurry phase reactor and continuously performed for 300 h without noticeable loss of activity in a fixed bed reactor, displaying excellent stability. The mixed products were successfully separated by distillation, and 99.18% purity of MMAc was obtained. Therefore, the reported DMM carbonylation to MMAc process has an excellent basis for industrial application.
- Chen, Fei,Shi, Lei,Bello, SuleimanSabo,Fan, Jiaqi,Wang, Yan,Zhang, Dongxi,Yao, Jie
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p. 1346 - 1353
(2020/02/04)
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- A novel vapor-phase catalytic synthetic approach for industrial production of 1,1,1,3,3,3-hexafluoroisopropyl methylether
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1,1,1,3,3,3-Hexafluoroisopropylmethyl ether (HFE-356mmz) is an important substitute for chlorofluorocarbons and hydrochlorofluorocarbons due to its zero ozone depletion potential and low global warming potential. However, mass production of HFE-356mmz remains a long-standing challenge. Herein, we applied metal fluorides as catalysts in the methylation of 1,1,1,3,3,3-hexafluoroisopropanol to produce HFE-356mmz for the first time. The catalyst not only improves the synthetic efficiency, but also makes the reaction solvent-free. The pollution-free, recyclable, and continuous synthetic process enables industrial production of HFE-356mmz. To optimize the synthetic efficiency, a series of metal fluorides (AlF3, MgF2, CaF2, SrF2, and BaF2) was used, among which MgF2 exhibited the highest activity. Through careful examination of each metal fluoride, it was found that the activity of the catalyst was determined by co-operative action of the surface acid–base properties and the total amount of surface acid sites. Based on these results, a rational mechanism for the vapor-phase methylation was proposed.
- Li, Wei,Yang, Gang,Lu, Fengniu,Zhang, Xiaoling
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- PRODUCTION OF ACETONITRILE AND/OR HYDROGEN CYANIDE FROM AMMONIA AND METHANOL
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The invention relates to a process for producing a product gas comprising acetonitrile and/or hydrogen cyanide from a feed stream comprising ammonia and methanol over a solid catalyst comprising a support, a first metal and a second metal on the support, wherein the first metal and the second metal are in the form of a chemical compound, wherein the first metal is Fe, Ru or Co and the second metal is Sn, Zn, or Ge. The pressure is ambient pressure or higher and the temperature lies in a range from about 400° C. to about 700° C. Thus, the process for producing acetonitrile and/or hydrogen cyanide from ammonia and methanol may be catalyzed by a single catalyst and may be carried out in a single reactor. The invention also relates to a catalyst, a method for activating a catalyst and use of a catalyst for catalysing production of acetonitrile and/or hydrogen cyanide from ammonia and methanol.
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-
Paragraph 0046-0049
(2020/04/10)
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- CERIA SUPPORTED PALLADIUM/CALCIUM CATALYST FOR HYDROGENATING CO2 TO DIMETHYL ETHER
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Catalysts for hydrogenation of CO2 to dimethyl ether. These catalysts comprise 0.1-10 wt % per total catalyst weight of a catalytic material containing Pd (e.g. metallic palladium), 0.05-5 wt % per total catalyst weight of a promoter containing Ca (e.g. metallic calcium), as well as 85-99 wt % of CeO2 as a catalyst support. Methods of preparing and characterizing the catalysts as well as processes for catalyzing the hydrogenation of CO2 to dimethyl ether and other byproducts such as methanol, carbon monoxide, and methane portrayed by reactant conversion., product selectivity, and catalyst stability are disclosed.
- -
-
Paragraph 0095-0096
(2020/05/14)
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- The Direct Partial Oxidation of Methane to Dimethyl Ether over Pt/Y2O3 Catalysts Using an NO/O2 Shuttle
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Using a mixture of NO + O2 as the oxidant enabled the direct selective oxidation of methane to dimethyl ether (DME) over Pt/Y2O3. The reaction was carried out in a fixed bed reactor at 0.1 MPa over a temperature range of 275–375 °C. During the activity tests, the only carbon-containing products were DME and CO2. The DME productivity (μmol gcat?1 h?1) was comparable to oxygenate productivities reported in the literature for strong oxidants (N2O, H2O2, O3). The NO + O2 mixture formed NO2, which acted as the oxygen atom carrier for the ultimate oxidant O2. During the methane partial oxidation reaction, NO and NO2 were not reduced to N2. In situ FTIR showed the formation of surface nitrate species, which are considered to be key intermediate species for the selective oxidation.
- Kobayashi, Yasukazu,Oyama, S. Ted,Vargheese, Vibin
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supporting information
p. 16644 - 16650
(2020/07/25)
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- Tailoring Interfacial Lewis Acid-Basic Pair on ZnO/4Mg1ZrOx Allows Dehydrogenative α-Methylenation of Alcohols with Methanol to Allylic Alcohols
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Allylic alcohols are the essential building blocks widely used in diverse streams of organic inventions for pharmaceuticals, fragrances, agrochemicals and polymers. Currently, allylic alcohols are industrially produced from petroleum-based feedstocks via atom uneconomic processes. More sustainable synthesis route for allylic alcohols is limited. Herein, a methodology for the direct and highly selective production of allylic alcohols has been accomplished by controlled dehydrogenative α-methylenation of alcohols with methanol. This transformation is enabled by interfacial Lewis acid-basic pair on tailor-made ZnO/4Mg1ZrOx mixed oxide. High selectivity (83～92%) of allylic alcohols is the consequence of alcohols acceptorless dehydrogenation to liberation of H2 and Meerwein-Ponndorf-Verley type hydrogen transfer onto C = O bonds of unsaturated aldehydes. Furthermore, the prepared ZnO/4Mg1ZrOx mixed oxide shows good stability after 200 h time on stream test. These observations could additionally allow us to design multifunctional solid acid-basic catalysts for the transformations of renewable oxygenates into value-added chemicals.
- Fu, Aixiao,Jiang, Shifeng,Liu, Qiang,Liu, Xiaoran,Liu, Xiuyun,Mu, Xindong,Sun, Mengqing,Wang, Xicheng,Xu, Guoqiang,Zhao, Lingling
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- A METHOD OF PREPARING ETHYLBENZENE
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The present invention provides a process for making ethylbenzene including reacting toluene with a C1 source in the presence of a zeolite catalyst in one or more reactor zones to form a product comprising ethylbenzene and maintaining a molar ratio of tolu
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-
Paragraph 0033-0038
(2021/01/23)
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- High catalytic activity of CuY catalysts prepared by high temperature anhydrous interaction for the oxidative carbonylation of methanol
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CuY catalysts were prepared by high temperature anhydrous interaction between NH4Y zeolite and copper(ii) acetylacetonate Cu(acac)2 and the activities were measured for the oxidative carbonylation of methanol to dimethyl carbonate under atmospheric pressure. The bulk and surface properties of the as-prepared catalyst were characterized by XRD, H2-TPR and XPS techniques. The activation atmosphere of the CuY catalyst and the testing temperature of the catalytic activity was systematically studied. During activation, nitrogen promotes the auto-reduction of Cu2+ to form the Cu+ active center, but deposited carbon on the surface of the CuY catalyst covers the active center, even plugging the channel, resulting in lower catalytic activity. Oxygen eliminates deposited carbon, but is not so good for the auto-reduction of Cu2+. Nitrogen doped with a small amount of oxygen not only eliminates the deposited carbon, but also promotes the auto-reduction of Cu2+ to form more Cu+ active centers. With the testing temperature increasing, the catalytic activity increases first and then decreases. When the testing temperature is 170 °C, the CuY catalyst with satisfactory activity and stability showed an excellent catalytic activity with 525.1 mg g-1 h-1 space time yield of DMC (STYDMC) and 18.9% methanol conversion. Then the longevity was investigated at 170 °C for 150 h. During the initial reaction period of 40 h, the STYDMC value was constant. In the next 20 h, the catalytic activity slightly decreased. But in the last 90 h, the catalytic performance is very stable and the STYDMC value remains 480 mg g-1 h-1. The main cause of deactivation is the growth of the particles.
- Wang, Yuchun,Liu, Zhaorong,Tan, Chao,Sun, Hong,Li, Zhong
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p. 3293 - 3300
(2020/02/04)
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- A novel microreaction strategy to fabricate superior hybrid zirconium and zinc oxides for methanol synthesis from CO2
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The synergetic interaction of solid solutions plays important roles in the reaction efficiency of CO2 hydrogenation, which is used to produce methanol. The effects of material mixing, impregnation, traditional coprecipitation, and microreaction synthesis on the structural and catalytic properties of ZnO/t-ZrO2 hybrid oxides were investigated. Although the impregnation effect caused a certain electronic structural modulation at the Zn/Zr interface, the pore structure blocking effect and low number of oxygen vacancy defects leaded to a low catalytic reaction efficiency. The solid solution structure enhanced the Zn/Zr interfacial interaction and increased the electron binding energy. More importantly, many oxygen vacancy defects were formed, which promoted CO2 activation. However, the solid solution structure was more affected by the preparation method. The solid solution formed from the microreaction exhibited excellent catalytic activity, thermal stability and regeneration performance due to a more uniform solid solution structure and abundant oxygen vacancy defects. The CO2 conversion rate, methanol selectivity, and methanol space-time yield (STY) under the conditions of H2/CO2 = 3:1, 320 °C, 3 MPa, GHSV = 12,000 ml g?1 h?1 reached 9.2 %, 93.1 %, and 0.35 gMeOH h?1gcat?1, respectively.
- Cao, Jianxin,Liu, Fei,Pan, Hongyan,Wang, Xiaodan,Wang, Xiuxiu,Wang, Yizhou,Yang, Chunliang,Yi, Yun
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- Strong Electronic Oxide-Support Interaction over In2O3/ZrO2for Highly Selective CO2Hydrogenation to Methanol
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Metal oxides are widely employed in heterogeneous catalysis, but it remains challenging to determine their exact structure and understand the reaction mechanisms at the molecular level due to their structural complexity, in particular for binary oxides. This paper describes the observation of the strong electronic interaction between In2O3 and monoclinic ZrO2 (m-ZrO2) by quasi-in-situ XPS experiments combined with theoretical studies, which leads to support-dependent methanol selectivity. In2O3/m-ZrO2 exhibits methanol selectivity up to 84.6% with a CO2 conversion of 12.1%. Moreover, at a wide range of temperatures, the methanol yield of In2O3/m-ZrO2 is much higher than that of In2O3/t-ZrO2 (t-: tetragonal), which is due to the high dispersion of the In-O-In structure over m-ZrO2 as determined by in situ Raman spectra. The electron transfer from m-ZrO2 to In2O3 is confirmed by XPS and DFT calculations and improves the electron density of In2O3, which promotes H2 dissociation and hydrogenation of formate intermediates to methanol. The concept of the electronic interaction between an oxide and a support provides guidelines to develop hydrogenation catalysts.
- Yang, Chengsheng,Pei, Chunlei,Luo, Ran,Liu, Sihang,Wang, Yanan,Wang, Zhongyan,Zhao, Zhi-Jian,Gong, Jinlong
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supporting information
p. 19523 - 19531
(2020/12/01)
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- Synthesis of High Dimensionally Structured Mo-Fe Mixed Metal Oxide and Its Catalytic Activity for Selective Oxidation of Methanol
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High-dimensionally structured Mo-Fe oxide (HDS-MoFeO) was synthesized through an assembly of structural units supplied from Keplerate-type polyoxometalate, {Mo72Fe30}, under an appropriate hydrothermal condition. HDS-MoFeO showed excellent catalytic activity for the selective oxidation of methanol with slightly lower selectivity for formaldehyde than that of a conventional Mo-Fe oxide catalyst.
- Hiyoshi, Norihito,Ishikawa, Satoshi,Kumaki, Masahiro,Shimoda, Kosuke,Tashiro, Masaya,Ueda, Wataru
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supporting information
(2020/04/15)
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- Direct Conversion of Methanol to Ethanol on the Metal-Carbon Interface
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Direct conversion of one-carbon (C1) compounds to two-carbon (C2) and multi-carbon compounds remains a critical challenge for converting non-petroleum resources to valuable chemicals or fuels. The key issue is the selective activation of C1 compounds, methanol, as well as the controlled formation of carbon-carbon (C?C) bonds. Herein, we achieve the direct electrocatalytic methanol to ethanol, an important chemical and energy candidate, with methanol conversion, ethanol selectivity, and faradic efficiency of 257.0 g ? m?2 ? h?1, 95.1 %, and 12.5 %, respectively. Furthermore, the appropriate participation of water, as a by-product from methanol electrocatalysis, in hydrogen evolution reaction (HER) facilitates electrocatalytic reaction of methanol. Mechanistic studies reveal hydroxymethyl and methyl radicals are formed on the electropositive low-valent metal sites and electronegative carbon vacancies, respectively, and then combined with each other to form ethanol at the metal/carbon interface. This work opens a unique route for high-efficient concerted redox conversion of methanol reactant to ethanol.
- Li, Yunhua,Lu, Junfeng,Wang, Xihui,Zhang, Hua,Wu, Xuee,Zhang, Kelvin H. L.,Ye, Jinyu,Zhan, Dongping
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p. 2277 - 2282
(2019/04/13)
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- Catalytic Performance of Layered Double Hydroxides (LDHs) Derived Materials in Gas-Solid and Liquid-Solid Phase Reactions
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Novel layered double hydroxides (LDHs) were prepared by a co-precipitation method and characterised using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). As-prepared LDH derived catalysts were first evaluated in the gas-phase conversion of methanol. The results indicate that LDH derived materials act as selective catalysts towards dimethyl ether (DME), methane or light olefins formation, depending on their chemical composition. For instance, CuAlOx showed a high selectivity in DME up to 88 %, whilst CuCoOx converted methanol to CH4, C3H8 and DME. NiFeOx allowed achieving a full methanol conversion selectively into CH4 during at least 1800 min. Besides, Ni and Cu-LDHs were successfully tested in the liquid phase benzyl alcohol (BzOH) oxidation leading to more than 50 % conversion. NiAl-LDH appeared as the best catalyst for benzaldehyde production with a 71 % conversion and 100 % selectivity.
- Huang, Liang,Megías-Sayago, Cristina,Bingre, Rogeria,Zheng, Qianwen,Wang, Qiang,Louis, Beno?t
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p. 3279 - 3286
(2019/06/27)
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- Supported Intermetallic PdZn Nanoparticles as Bifunctional Catalysts for the Direct Synthesis of Dimethyl Ether from CO-Rich Synthesis Gas
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The single-step syngas-to-dimethyl ether (STD) process entails economic and technical advantages over the current industrial two-step process. Pd/ZnO-based catalysts have recently emerged as interesting alternatives to currently used Cu/ZnO/Al2O3 catalysts, but the nature of the active site(s), the reaction mechanism, and the role of Pd and ZnO in the solid catalyst are not well established. Now, Zn-stabilized Pd colloids with a size of 2 nm served as the key building blocks for the methanol active component in bifunctional Pd/ZnO-γ-Al2O3 catalysts. The catalysts were characterized by combining high-pressure operando X-ray absorption spectroscopy and DFT calculations. The enhanced stability, longevity, and high dimethyl ether selectivity observed makes Pd/ZnO-γ-Al2O3 an effective alternative system for the STD process compared to Cu/ZnO/γ-Al2O3.
- Gentzen, Manuel,Doronkin, Dmitry E.,Sheppard, Thomas L.,Zimina, Anna,Li, Haisheng,Jelic, Jelena,Studt, Felix,Grunwaldt, Jan-Dierk,Sauer, J?rg,Behrens, Silke
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supporting information
p. 15655 - 15659
(2019/10/28)
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- Dimethyl Ether Conversion to Gasoline Hydrocarbons over Nanosized Zeolite Catalysts: Effect of Modifier Nature
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Abstract—: The effect of modifier nature on the catalytic properties of nanosized zeolite catalysts used for the synthesis of liquid hydrocarbons from dimethyl ether is studied. It is shown that selectivity of the catalysts for liquid hydrocarbons depends on both the modifier nature and the initial feedstock composition. The best activity and selectivity for liquid hydrocarbons are exhibited by the samples modified with zinc and magnesium. The content of aromatic hydrocarbons in the products decreases appreciably when the catalysts are additionally modified with noble metals and the reaction is carried out in the medium of hydrogen.
- Snatenkova, Yu. M.,Kolesnichenko,Matieva,Maximov
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p. 1331 - 1336
(2020/01/02)
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- CO2 Hydrogenation on Cu/Al2O3: Role of the Metal/Support Interface in Driving Activity and Selectivity of a Bifunctional Catalyst
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Selective hydrogenation of CO2 into methanol is a key sustainable technology, where Cu/Al2O3 prepared by surface organometallic chemistry displays high activity towards CO2 hydrogenation compared to Cu/SiO2, yielding CH3OH, dimethyl ether (DME), and CO. CH3OH formation rate increases due to the metal–oxide interface and involves formate intermediates according to advanced spectroscopy and DFT calculations. Al2O3 promotes the subsequent conversion of CH3OH to DME, showing bifunctional catalysis, but also increases the rate of CO formation. The latter takes place 1) directly by activation of CO2 at the metal–oxide interface, and 2) indirectly by the conversion of formate surface species and CH3OH to methyl formate, which is further decomposed into CH3OH and CO. This study shows how Al2O3, a Lewis acidic and non-reducible support, can promote CO2 hydrogenation by enabling multiple competitive reaction pathways on the oxide and metal–oxide interface.
- Lam, Erwin,Corral-Pérez, Juan José,Larmier, Kim,Noh, Gina,Wolf, Patrick,Comas-Vives, Aleix,Urakawa, Atsushi,Copéret, Christophe
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supporting information
p. 13989 - 13996
(2019/08/30)
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- The role of weak Lewis acid sites for methanol thiolation
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Weak Lewis acid sites combined with strong base sites of Cs+ supported on WS2 and γ-Al2O3 act as active sites in the thiolation of methanol. The acid-base pairs dissociate methanol upon adsorption. The formed surface alcoholate and the corresponding sulfuryl groups enable the substitution of oxygen for sulfur in a Langmuir-Hinshelwood mechanism. Stronger Lewis acid sites catalyze dimethyl ether formation via the Eley-Rideal mechanism in which methoxy groups react with gas phase methanol. The results demonstrate the importance of adjusting the acid-base strength in oxides to selectively catalyze substitution reactions.
- Weber-Stockbauer, Manuel,Gutiérrez, Oliver Y.,Bermejo-Deval, Ricardo,Lercher, Johannes A.
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p. 509 - 516
(2019/01/28)
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- Continuous Partial Oxidation of Methane to Methanol Catalyzed by Diffusion-Paired Copper Dimers in Copper-Exchanged Zeolites
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Copper-exchanged zeolites can continuously and selectively catalyze the partial oxidation of methane to methanol using only oxygen and water at low temperatures, but the genesis and nature of the active sites are currently unknown. Herein, we demonstrate that this reaction is catalyzed by a [Cu-O-Cu]2+ motif that forms via a hypothesized proton-aided diffusion of hydrated Cu ions within the cages of SSZ-13 zeolites. While various Cu configurations may be present and active for methane oxidation, a dimeric Cu motif is the primary active site for selective partial methane oxidation. Mechanistically, CH4 activation proceeds via rate-determining C-H scission to form a surface-bound C1 intermediate that can either be desorbed as methanol in the presence of H2O/H+ or completely oxidized to CO2 by gas-phase O2. High partial oxidation selectivity can be obtained with (i) high methane and water partial pressures and (ii) maximizing Cu dimer formation by using zeolites with high Al content and low Cu loadings.
- Dinh, Kimberly T.,Sullivan, Mark M.,Narsimhan, Karthik,Serna, Pedro,Meyer, Randall J.,Dincǎ, Mircea,Román-Leshkov, Yuriy
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supporting information
p. 11641 - 11650
(2019/08/20)
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- Deacylative transformations of ketones via aromatization-promoted C–C bond activation
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Carbon–hydrogen (C–H) and carbon–carbon (C–C) bonds are the main constituents of organic matter. Recent advances in C–H functionalization technology have vastly expanded our toolbox for organic synthesis1. By contrast, C–C activation methods that enable editing of the molecular skeleton remain limited2–7. Several methods have been proposed for catalytic C–C activation, particularly with ketone substrates, that are typically promoted by using either ring-strain release as a thermodynamic driving force4,6 or directing groups5,7 to control the reaction outcome. Although effective, these strategies require substrates that contain highly strained ketones or a preinstalled directing group, or are limited to more specialist substrate classes5. Here we report a general C–C activation mode driven by aromatization of a pre-aromatic intermediate formed in situ. This reaction is suitable for various ketone substrates, is catalysed by an iridium/phosphine combination and is promoted by a hydrazine reagent and 1,3-dienes. Specifically, the acyl group is removed from the ketone and transformed to a pyrazole, and the resulting alkyl fragment undergoes various transformations. These include the deacetylation of methyl ketones, carbenoid-free formal homologation of aliphatic linear ketones and deconstructive pyrazole synthesis from cyclic ketones. Given that ketones are prevalent in feedstock chemicals, natural products and pharmaceuticals, these transformations could offer strategic bond disconnections in the synthesis of complex bioactive molecules.
- Xu, Yan,Qi, Xiaotian,Zheng, Pengfei,Berti, Carlo C.,Liu, Peng,Dong, Guangbin
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p. 373 - 378
(2019/05/22)
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- CATALYSTS COMPRISING SILICON MODIFIED NICKEL
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Nickel-based catalysts comprising silicon modified nickel (nickel silicate) are provided, as are methods for using the catalysts to i) convert methane to CO and H2 (e.g. for use in synthetic chemical compound production); or to ii) convert methane to oxygenated hydrocarbons e.g. one or more of methanol, acetone, formaldehyde, and dimethyl ether. The catalysts are bifunctional and comprise both Ni metallic catalytic sites and acidic nickel-silicon catalytic sites, and the conversions are performed under moderate reaction conditions.
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Paragraph 0110
(2019/09/20)
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- Direct Conversion of Syngas into Methyl Acetate, Ethanol, and Ethylene by Relay Catalysis via the Intermediate Dimethyl Ether
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Selective conversion of syngas (CO/H2) into C2+ oxygenates is a highly attractive but challenging target. Herein, we report the direct conversion of syngas into methyl acetate (MA) by relay catalysis. MA can be formed at a lower temperature (ca. 473 K) using Cu-Zn-Al oxide/H-ZSM-5 and zeolite mordenite (H-MOR) catalysts separated by quartz wool (denoted as Cu-Zn-Al/H-ZSM-5|H-MOR) and also at higher temperatures (603–643 K) without significant deactivation using spinel-structured ZnAl2O4|H-MOR. The selectivity of MA and acetic acid (AA) reaches 87 % at a CO conversion of 11 % at 643 K. Dimethyl ether (DME) is the key intermediate and the carbonylation of DME results in MA with high selectivity. We found that the relay catalysis using ZnAl2O4|H-MOR|ZnAl2O4 gives ethanol as the major product, while ethylene is formed with a layer-by-layer ZnAl2O4|H-MOR|ZnAl2O4|H-MOR combination. Close proximity between ZnAl2O4 and H-MOR increases ethylene selectivity to 65 %.
- Zhou, Wei,Kang, Jincan,Cheng, Kang,He, Shun,Shi, Jiaqing,Zhou, Cheng,Zhang, Qinghong,Chen, Junchao,Peng, Luming,Chen, Mingshu,Wang, Ye
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p. 12012 - 12016
(2018/09/10)
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- Influence of Phase Composition of Bulk Tungsten Vanadium Oxides on the Aerobic Transformation of Methanol and Glycerol
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A series of W–V–O catalysts with different m-WO3 and h-WO3 phase contents were hydrothermally synthesized by employing different tungsten, vanadium, and ammonium precursors and characterized by powder XRD, N2 adsorption, SEM, X-ray energy-dispersive spectroscopy, thermogravimetric analysis, Raman and FTIR spectroscopy, NH3 temperature programmed desorption, H2 temperature-programmed reduction, and XPS. Finally, the acid/redox properties were analyzed by using aerobic transformation of methanol as a characterization reaction. A correlation between phase composition as well as acid and redox properties was observed, which were correlated to the catalytic performance of the title materials in a one-pot oxydehydration reaction of glycerol. The hexagonal tungsten bronze (h-WO3) phase shows a significantly higher concentration of acid sites than monoclinic m-WO3, so that the acid properties of W–V–O oxides are directly related to the presence of h-WO3 crystals. The presence of a higher concentration of acid sites in V-containing h-WO3 crystals is a key factor to achieve high selectivity to both acrolein and acrylic acid during one-pot glycerol oxydehydration. Also, V sites in h-WO3 show higher selectivity in the consecutive reaction (partial oxidation of acrolein to acrylic acid), while V sites in the m-WO3 phase fundamentally lead to the formation of carbon oxides.
- Delgado, Daniel,Chieregato, Alessandro,Soriano, M. Dolores,Rodríguez-Aguado, Elena,Ruiz-Rodríguez, Lidia,Rodríguez-Castellón, Enrique,López Nieto, José M.
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p. 1204 - 1211
(2018/03/22)
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- Vanadium oxide catalyst supported on CeO2—ZrO2 for dimethyl ether production via oxidative dehydration of methanol
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A catalyst of vanadium oxide supported on cerium oxide and zirconium oxide is specified. The catalyst comprises 0.1-10 wt % vanadium oxide relative to the total catalyst weight, and the catalyst is in the form of microparticles. A method using a wetness impregnation technique to produce the catalyst is described. The use of the catalyst in the oxidative dehydration of methanol to produce dimethyl ether is specified, along with the catalyst's stability for reaction periods of 50 or more hours.
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Page/Page column 15-17
(2018/12/02)
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- Mn/CeO2 CATALYST FOR DIMETHYL ETHER PRODUCTION VIA OXIDATIVE DEHYDRATION OF METHANOL
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A method of producing dimethyl ether involving contacting methanol with a catalyst in the presence of oxygen in a reactor to form the dimethyl ether. The catalyst comprises manganese on a cerium oxide catalyst support, wherein a weight ratio of manganese to the cerium oxide catalyst support is in the range of 0.005 to 0.5. Further, a method of manufacturing the catalyst, including mixing cerium oxide (CeO2) with a solution comprising manganese salt and a solvent, evaporating the solvent, followed by drying and calcining to form a catalyst which comprises manganese on a cerium oxide catalyst support, wherein a weight ratio of manganese to the cerium oxide catalyst support is in the range of 0.005 to 0.5.
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Paragraph 0054; 0061; 0068; 0070; 0075
(2018/10/19)
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- Bifunctional catalysts based on colloidal Cu/Zn nanoparticles for the direct conversion of synthesis gas to dimethyl ether and hydrocarbons
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Hybrid catalysts were prepared using well-defined, colloidal Cu/Zn-based nanoparticles as building units. The nanoparticles were immobilized on acidic supports (i.e., γ-Al2O3, HZSM-5, and HY) to yield a series of bifunctional catalysts with a close proximity of active sites for both methanol synthesis and its further conversion to dimethyl ether (DME) or hydrocarbons (HCs). By this model kit principle, a high comparability of the bifunctional catalysts was ensured. The catalysts were characterized in depth regarding their structure and catalytic performance in the conversion of CO-rich synthesis gas. In situ XAS studies demonstrated the formation of the active phase under reducing conditions. The present study revealed important material parameters to control activity and selectivity of the bifunctional catalysts either towards DME or liquefied petroleum gas (LPG) products in the direct conversion of simulated biomass-derived synthesis gas. In particular, Cu loading, pore structure and Si:Al ratio were investigated.
- Gentzen,Doronkin,Sheppard,Grunwaldt,Sauer,Behrens
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- METHOD AND APPARATUS FOR PRODUCING ACETIC ACID
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A process for stably and safely producing acetic acid without increasing an internal pressure of a distillation column is provided. The process comprises (1) a carbonylation reaction step for allowing methanol to react with carbon monoxide; (2) a flash step for separating the reaction mixture into a volatile phase and a less-volatile phase; (3) a first distillation step for separating the volatile phase into a first overhead and a crude acetic acid stream rich in acetic acid; and (4) a separation step for separating at least acetaldehyde from the first overhead. The separation step (4) comprises (6) a second distillation step for distilling the first overhead while controlling an internal pressure of a distillation column provided with a pressure control unit 68 to form a second overhead rich in acetaldehyde and methyl iodide and a bottom or lower stream, and (7) an extraction step for extracting acetaldehyde from the second overhead to form an extract rich in acetaldehyde and a raffinate rich in methyl iodide.
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Paragraph 0128-01311
(2018/08/30)
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- Iron-Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers
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Among all metathesis reactions known to date in organic chemistry, the metathesis of multiple bonds such as alkenes and alkynes has evolved into one of the most powerful methods to construct molecular complexity. In contrast, metathesis reactions involving single bonds are scarce and far less developed, particularly in the context of synthetically valuable ring-closing reactions. Herein, we report an iron-catalyzed ring-closing metathesis of aliphatic ethers for the synthesis of substituted tetrahydropyrans and tetrahydrofurans, as well as morpholines and polycyclic ethers. This transformation is enabled by a simple iron catalyst and likely proceeds via cyclic oxonium intermediates.
- Biberger, Tobias,Makai, Szabolcs,Lian, Zhong,Morandi, Bill
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supporting information
p. 6940 - 6944
(2018/05/14)
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- Selective Production of Oxygenates from Carbon Dioxide Hydrogenation over a Mesoporous-Silica-Supported Copper-Gallium Nanocomposite Catalyst
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The hydrogenation of CO2 to oxygenates (methanol and dimethyl ether; DME) was investigated over bifunctional supported Cu catalysts promoted with Ga. The supported Cu-Ga nanocomposite catalysts were characterized by using XRD, TEM with energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and H2 temperature-programmed reduction. In comparison with Cu-SBA-15-based catalysts, the Ga-promoted catalyst prepared by the urea deposition method (Cu-Ga/SBA-15-UDP) was more active and selective for CO2 hydrogenation to oxygenates. The use of Ga as the promoter led to increased acidic sites, which was confirmed by using NH3 temperature-programmed deposition and IR spectroscopy with pyridine and 2,6-lutidine as probe molecules. The favorable effect of Ga on the CO2 conversion and selectivity to oxygenates may come from the strong interaction of Ga with silica, which is responsible for the enhanced metal surface area, the formation of the nanocomposite, and the metal dispersion. Notably, the incorporation of Ga into Cu/SiO2 led to a several-fold higher rate for methanol formation (13.12 μmol gCu ?1 s?1) with a reasonable rate for DME formation (2.15 μmol gCu ?1 s?1) compared to Cu/SiO2 catalysts.
- Hengne, Amol M.,Bhatte, Kushal D.,Ould-Chikh, Samy,Saih, Youssef,Basset, Jean Marie,Huang, Kuo-Wei
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p. 1360 - 1369
(2018/03/30)
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- The influence of composition on the functionality of hybrid CuO-ZnO-Al2O3/HZSM-5 for the synthesis of DME from CO2 hydrogenation
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A series of CuO-ZnO-Al2O3/HZSM-5 hybrid catalysts with different Cu/Zn ratios and disparate Al2O3 doping were prepared and characterized by XRD, BET, H2-TPR, NH3-TPD and XPS techniques. The optimal Cu/Zn ratio is 7 : 3, and the introduction of a suitable amount of Al2O3 to form hybrid catalysts increased the BET specific area and micropore volume, facilitated the CuO dispersion, decreased the CuO crystallite size, increased the interaction between CuO and ZnO, enhanced the number of weak acid sites, altered the copper chemical state and improved the catalytic performance consequently. The highest CO2 conversion, DME selectivity and DME yield of 27.3%, 67.1% and 18.3%, respectively, were observed over the CZA7H catalyst. The suitable temperature of 260 °C and the appropriate space velocity of 1500 h-1 for one-step synthesis of dimethyl ether (DME) from carbon dioxide (CO2) hydrogenation were also investigated. The 50 h stability of the CZA7H catalyst was also tested.
- Hu, Yubing,Zhang, Yajing,Du, Jie,Li, Chunyan,Wang, Kangjun,Liu, Lidong,Yu, Xinrui,Wang, Kai,Liu, Nan
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p. 30387 - 30395
(2018/09/11)
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