- Hydrocarbon reactions on MoS2 revisited, II: Catalytic properties in alkene hydrogenation, cis-trans isomerization, and H2/D2 exchange
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MoS2 prepared by thermal decomposition of ammonium tetrathiomolybdate in inert gas at temperatures up to 773 K was activated by treatments involving thermoevacuation at 723 K and/or reduction at 573 K. The effect of different activations on the activity in ethylene hydrogenation, cis-trans isomerization of 2-butene, and H2/D2 isotope exchange (all measured at temperatures around 473 K) was compared, taking into account the extent of Mo exposition as measured by oxygen chemisorption. It was found that activation had a widely varying impact on the test reactions, indicating that these proceed on sites with different numbers of vacancies. Hydrogenation activity was boosted by two orders of magnitude when reduction of the catalyst at 573 K was followed by thermoevacuation at 723 K, whereas this change was moderate with H2/D2 exchange and negative with cis-trans isomerization. For the latter reaction, mere thermoevacuation was a suitable activation, and the impact of subsequent catalyst reduction was negative, whereas appreciable activity in the former reactions was obtained only when thermoevacuation was combined with a subsequent reduction. The data suggest that all three reactions proceeded on different sites, probably 3 vacancies per Mo for olefin hydrogenation, 2 vacancies per Mo for H2/D2 exchange, and 1 vacancy per Mo for cis-trans isomerization, with the latter two reactions involving adjacent {single bond}SH groups. Sites with greater Mo exposure than stated may be suitable for H2/D2 exchange but not for cis-trans isomerization. With increasing severity of the activation treatments, sites with a small number of vacancies appeared to combine and migrate toward the rims or to escape into the bulk. Therefore, very high hydrogenation activity may be seen on surfaces with an oxygen chemisorption capacity far from the maximum value occurring after less drastic treatments. Our findings imply that a combination of chemisorption studies with test reactions may be a valuable tool for surface characterization of sulfide catalysts.
- Polyakov, Mykola,Poisot, Martha,Bensch, Wolfgang,Muhler, Martin,Gruenert, Wolfgang
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- Stereoselectivity in the Metathesis Reaction of But-2-ene on a β-Titanium Oxide-supported Molybdenum Oyxide
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With MoOx/β-TiO2 as catalyst the stereoselective formation of cis- and trans-but-2-ene is observed in the metathesis of equimolar mixtures of cis-- and -but-2-ene, and trans-- and --but-2-ene, respectively; the yields of cis- and trans-but-2-ene from reactions of the corresponding pent-2-ene isomers are in good agreement, but metathesis of propene selectively yields trans-but-2-ene.
- Tanaka, Katsumi,Tanaka, Ken-ichi,Miyahara, Koshiro
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- The Photocatalytic Isomerization of 2-Butenes on ZrO2 Catalyst with Low Coordinated Surface Sites
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The photocatalyzed isomerization of cis-2-butene has been investigated on active ZrO2 catalysts which exhibited a typical photoluminescence associated with low coordinated surface sites.A geometrical isomerization reaction occurred predominantly and with high efficiency under UV-irradiation of the ZrO2 catalyst in the presence of cis-2-butene.A good parallel between the photoluminescence intensity and the rate of photocatalytic activity clearly indicated that the low coordinated surface sites play a significant role in the photocatalytic isomerization of cis-2-butene on the active ZrO2 catalysts.
- Moon, Sang-Chul,Hieida, Takeshi,Yamashita, Hiromi,Anpo, Masakazu
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- The Isomerization of cis-2-Butene over SO2-adsorbing Mg(OH)2 and MgO
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The reaction of butenes caused by the surface compounds formed from SO2 on Mg(OH)2 or MgO has been studied.It has been shown that the cis-trans isomerizatin of 2-butene is selectively induced by the sulfur compounds.This specific isomerization has been explained by the previously proposed mechanism that the reaction is accompanied by the copolymerization of 2-butene and SO2.The infrared spectroscopic study on the sulfur compounds formed on Mg(OH)2 or on MgO has demonstrated the presence of SO32-, SO42-, or sulfinato complexes.The formation of these surface species may cause strong electrostatic field on the surface, resulting in the polarization of reactant molecules, which is necessary for the initiation of the copolymerization or of the cis-trans isomerization.It has been shown, however, that the presence of weakly adsorbed SO2 is essential for determining the catalytic activities of the solids in the SO2-induced isomerization.
- Otsuka, Kiyoshi,Tanaka, Kimiaki,Morikawa, Akira
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- Sulfide catalysis without coordinatively unsaturated sites: Hydrogenation, cis-trans isomerization, and H2/D2 scrambling over MoS2 and WS2
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Simple test reactions as ethene hydrogenation, 2-butene cis-trans isomerization and H2/D2 scrambling were shown to be catalyzed by MoS2 and WS2 in surface states which did not chemisorb oxygen and were, according to XPS analysis, saturated by sulfide species. This is a clear experimental disproof of classical concepts that require coordinative unsaturation for catalytic reactions to occur on such surfaces. It supports new concepts developed on model catalysts and by theoretical calculations so far, which have been in need of confirmation from real catalysis.
- Drescher, Thomas,Niefind, Felix,Bensch, Wolfgang,Gruenert, Wolfgang
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- A Novel Metathesis Catalyst Consisting of Non-transition Elements. The Metathesis of Alkenes over Tetramethyltin/Dehydroxylated Alumina
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Sn(CH3)4/Al2O3 prepared by the deposition of Sn(CH3)4 to alumina which was previously dehydroxylated by heating at 773-1223 K was found to be an active catalyst for the metathesis of alkenes.The catalytic activity greatly depended on the pretreatment temperature of the alumina and the amount of Sn(CH3)4 deposited.
- Ahn, Ho-Geun,Yamamoto, Kei,Nakamura, Ryuichi,Niiyama, Hiroo
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- PHOTOINDUCED METATHESIS REACTION OF C3H6 ON SUPPORTED MoO3 CATALYST
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Ultraviolet irradiation of MoO3 supported on porous Vycor glass (PVG) in the presence of C3H4 has been found to induce the formation of approximately equimolar amounts of C2H4 and 2-C4H8 as well as a small amount of CH3CHO, suggesting that the metathesis reaction of C3H4 occurs.The dependence of the yields upon the excitation wavelenght is in good agreement with the excitation band of the phosphorescence of MoO3/PVG, wich arises from the charge-transfer transition .The quenching of the posphorescence of MoO3/PVG and the decrease in the yield of C3H4 metathesis on adding O2 and CO suggest that the photoinduced metathesis reaction is closely associated with the charge-transfer excited triplet state of MoO3/PVG.From these results, together with those of e.s.r. experiments reported previously, the mechanism of the photoinduced C3H4 metathesis, especially the primary process of metal-carbene formation, is discussed.
- Anpo, Masakazu,Tanahashi, Ichiro,Kubokawa, Yutaka
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- Photocatalyzed Isomerization of Butenes over Metal Sulfides. High Photocatalytic Activity and Its Origin
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Photocatalytic activity of CdS and ZnS for the cis-trans isomerization of 2-butene is much higher than that of TiO2 and ZnO, though the double bond shift isomerization to 1-butene hardly proceeds in contrast with the case of the oxides.The addition of O2 or NO molecules leads to the remarkable inhibition of photocatalyzed isomerization.From these results together with the ESR measurements before and after UV irradiation of the sulfide catalyst either in the presence or in the absence of butene, the following conclusions emerge: sulfur radicals such as Sn, which are produced by the hole trapping by lattice S2- ions and/or sulfur clusters existing in the catalyst inherently, play a significant role in the weakening of the C=C double bond of 2-butene via the interaction with the molecules; the stability of such sulfur radicals results in the much higher photocatalytic activity of CdS and ZnS catalysts as compared with that of metal oxide catalysts.
- Kodama, Sukeya,Matsumoto, Atsushi,Kubokawa, Yutaka,Anpo, Masakazu
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- Tuning crystal phase of molybdenum carbide catalyst to induce the different selective hydrogenation performance
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α-MoC, β-Mo2C, and MoC-Mo2C were synthesized and investigated in the selective hydrogenation of 1,3-butadiene to understand the effect of crystal phases. The catalysts were characterized by XRD, N2-physisorption, SEM, TEM, XPS and chemisorptions. The adsorption properties and electronic properties over MoC(001) and Mo2C(001) were investigated by DFT calculations. The catalysts were evaluated at low and high temperatures in a fixed-bed reactor. β-Mo2C exhibits high activity and low butenes selectivity, due to the high concentration of hydrogen at each active site as well as the stronger adsorption and higher capacity of alkene; MoC-Mo2C shows better stability due to synergetic effect. At high temperature, the reaction rate is more dependent on the PH2 than PC4H6. Increasing PH2 could promote the activity and reduce oligomers formation. β-Mo2C exhibits the best performance at high temperatures concerning its high activity and the inhibition of oligomerization. This work is valuable for the non-precious metal catalyst development.
- Ding, Ziluo,Hou, Ruijun,Sun, Kening,Xu, Yamei,Yang, Qiuchen
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- Regioselective Gas-Phase n-Butane Transfer Dehydrogenation via Silica-Supported Pincer-Iridium Complexes
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The production of olefins via on-purpose dehydrogenation of alkanes allows for a more efficient, selective and lower cost alternative to processes such as steam cracking. Silica-supported pincer-iridium complexes of the form [(≡SiO?R4POCOP)Ir(CO)] (R4POCOP=κ3-C6H3-2,6-(OPR2)2) are effective for acceptorless alkane dehydrogenation, and have been shown stable up to 300 °C. However, while solution-phase analogues of such species have demonstrated high regioselectivity for terminal olefin production under transfer dehydrogenation conditions at or below 240 °C, in open systems at 300 °C, regioselectivity under acceptorless dehydrogenation conditions is consistently low. In this work, complexes [(≡SiO?tBu4POCOP)Ir(CO)] (1) and [(≡SiO?iPr4PCP)Ir(CO)] (2) were synthesized via immobilization of molecular precursors. These complexes were used for gas-phase butane transfer dehydrogenation using increasingly sterically demanding olefins, resulting in observed selectivities of up to 77 %. The results indicate that the active site is conserved upon immobilization.
- Sheludko, Boris,Castro, Cristina F.,Khalap, Chaitanya A.,Emge, Thomas J.,Goldman, Alan S.,Celik, Fuat E.
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p. 407 - 415
(2020/12/01)
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- CATALYTIC HYDROCARBON DEHYDROGENATION
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A catalyst for dehydrogenation of hydrocarbons includes a support including zirconium oxide and Linde type L zeolite (L-zeolite). A concentration of the zirconium oxide in the catalyst is in a range of from 0.1 weight percent (wt. %) to 20 wt. %. The catalyst includes from 5 wt. % to 15 wt. % of an alkali metal or alkaline earth metal. The catalyst includes from 0.1 wt. % to 10 wt. % of tin. The catalyst includes from 0.1 wt. % to 8 wt. % of a platinum group metal. The alkali metal or alkaline earth metal, tin, and platinum group metal are disposed on the support.
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Paragraph 0063; 0064; 0124; 0125
(2021/03/13)
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- Oxidative Addition of Aryl and Alkyl Halides to a Reduced Iron Pincer Complex
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The two-electron oxidative addition of aryl and alkyl halides to a reduced iron dinitrogen complex with a strong-field tridentate pincer ligand has been demonstrated. Addition of iodobenzene or bromobenzene to (3,5-Me2MesCNC)Fe(N2)2 (3,5-Me2MesCNC = 2,6-(2,4,6-Me-C6H2-imidazol-2-ylidene)2-3,5-Me2-pyridine) resulted in rapid oxidative addition and formation of the diamagnetic, octahedral Fe(II) products (3,5-Me2MesCNC)Fe(Ph)(N2)(X), where X = I or Br. Competition experiments established the relative rate of oxidative addition of aryl halides as I > Br > Cl. A linear free energy of relative reaction rates of electronically differentiated aryl bromides (ρ = 1.5) was consistent with a concerted-type pathway. The oxidative addition of alkyl halides such as methyl-, isobutyl-, or neopentyl halides was also rapid at room temperature, but substrates with more accessible β-hydrogen positions (e.g., 1-bromobutane) underwent subsequent β-hydride elimination. Cyclization of an alkyl halide containing a radical clock and epimerization of neohexyl iodide-d2 upon oxidative addition to (3,5-Me2MesCNC)Fe(N2)2 are consistent with radical intermediates during C(sp3)-X bond cleavage. Importantly, while C(sp2)-X and C(sp3)-X oxidative addition produces net two-electron chemistry, the preferred pathway for obtaining the products is concerted and stepwise, respectively.
- Rummelt, Stephan M.,Peterson, Paul O.,Zhong, Hongyu,Chirik, Paul J.
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supporting information
p. 5928 - 5936
(2021/05/06)
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- Selective dehydration of 1-butanol to butenes over silica supported heteropolyacid catalysts: Mechanistic aspect
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Butenes are considered as important olefinic building block to produce fuels/fuel additives and commodity chemicals. In the present investigation, selective dehydration of 1-butanol to butenes was studied in a continuous-flow fixed-bed reactor using various silica-supported heteropolyacid (HPA) catalysts such as phosphotungstic acid (PTA), silicotungstic acid (STA), phosphomolybdic acid (PMA), and silicomolybdic acid (SMA) as the solid acid catalysts. The physicochemical properties of these HPA were determined by BET, powder XRD, FTIR, NH3-TPD, and Py-FTIR. The acid strength and Br?nsted/Lewis (B/L) acid ratio were increased with higher loading of HPA on silica. The nature of HPA (addenda and hetero atom) and loading of HPA are important factors for the dehydration of 1-butanol and selectivity towards butenes. PTA and STA showed superior catalytic activity than PMA and SMA. The reaction temperature and WHSV also strongly affected the butanol conversion and selectivity of butenes. The selectivity of di-n?butyl ether decreases with the rising temperature from 523 K to 623 K. The isomerization of 1-butene leading to the formation of other butene isomers depends on the HPA loading, temperature, and WHSV. The presence of molybdenum addendum atom in PMA and SMA promotes dehydrogenation and hydrogenation, leading to the formation of various light hydrocarbons. The 20PTA/SiO2 catalyst afforded 99.8% selectivity towards butenes at quantitative conversion of 1-butanol, whereas the 20STA/SiO2 catalyst gave nearly 97.0% conversion of 1-butanol and 99.9% butenes selectivity at 673 K, 37.4 h?1 of WHSV.
- Dutta, Saikat,Kella, Tatinaidu,Mal, Sib Sankar,Shee, Debaprasad,Vennathan, Anjana Anandan
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- Tandem catalysts for the selective hydrogenation of butadiene with hydrogen generated from the decomposition of formic acid
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We report for the first time the selective hydrogenation of 1,3-butadiene to butene using formic acid as the hydrogen source with 1 wt% Pd/carbon in a continuous flow reactor. The catalytic results show that the selectivity is even higher when formic acid is used compared to gas hydrogen.
- Carrales-Alvarado, D. H.,Dongil, A. B.,Guerrero-Ruiz, A.,Rodríguez-Ramos, I.
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supporting information
p. 6479 - 6482
(2021/07/07)
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- A selective and stable Fe/TiO2catalyst for selective hydrogenation of butadiene in alkene-rich stream
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The replacement of precious metals by more abundant and therefore much less expensive metals remains a very important challenge in catalysis. A Fe/TiO2catalyst prepared by deposition-precipitation with urea showed very high selectivity to alkenes (>99%), even at high conversion (>90%), in selective hydrogenation of butadiene in an excess of propene. Its activity is very stable at 175 °C whereas the catalyst deactivates at 50 °C, although it is also initially very active. The presence of metallic iron seems to be necessary to ensure these excellent performances.
- Casale, Sandra,Delannoy, Laurent,Louis, Catherine,Méthivier, Christophe,Santander de Soto, Laura,Wang, Zhao
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supporting information
p. 7031 - 7034
(2021/07/21)
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- Pt/TS-1 catalysts: Effect of the platinum loading method on the dehydrogenation of n-butane
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A series of catalysts in which platinum was supported on the crystalline pure titanium silicalite (TS-1) were prepared using two different loading methods, namely, an ethylene glycol (EG) reduction method and the conventional incipient wetness impregnation (IM) technique. Various characterization techniques were used to study the effect of the loading method on the physicochemical and morphological properties of the prepared catalysts. Also the effect of the platinum-loading method on the dehydrogenation of n-butane was investigated in a fixed-bed reactor. The results show that the EG method favors the formation of a more-concentrated Pt dispersion, which results in much better catalytic activities for the selective formation of butenes and butadiene (> 97 %). This phenomenon is interpreted by carrying out density functional theory (DFT) calculations with focus on the relationship between the coverage of n-butane on Pt surface and the activation barrier for the first C[sbnd]H bond cleavage.
- Shao, Mingyuan,Hu, Chaoquan,Xu, Xuebing,Song, Yang,Zhu, Qingshan
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- METHOD TO PRODUCE C4 OLEFINS FROM NATURAL GAS-DERIVED ACETYLENE
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In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, the disclosure relates to a method for producing C4 olefins from acetylene using supported metal-based catalysts and metal-based promoters. The method is inexpensive, efficient, and environmentally sound. Additionally, the method is selective for C4 olefins and other value-added products based on changes to reaction parameters including temperature, feed gas composition, and promoter identity. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.
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Paragraph 0015; 0016; 0019; 0020; 0246
(2021/10/22)
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- Mechanistic Interrogation of Alkyne Hydroarylations Catalyzed by Highly Reduced, Single-Component Cobalt Complexes
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Highly reactive catalysts for ortho-hydroarylations of alkynes have previously been reported to result from activation of CoBr2 by Grignard reagents, but the operative mechanism and identity of the active cobalt species have been undefined. A mechanistic analysis of a related system, involving hydroarylations of a (N-aryl)aryl ethanimine with diphenylacetylene, was performed using isolable reduced Co complexes. Studies of the stoichiometric reaction of Co(I) or Co(II) precursors with CyMgCl implicated catalyst initiation via a β-H elimination/deprotonation pathway. The resulting single-component Co(-I) complex is proposed as the direct pre-catalyst. Michaelis-Menten enzyme kinetic studies provide mechanistic details regarding the catalytic dependence on substrate. The (N-aryl)aryl ethanimine substrate exhibited saturation-like behavior, whereas alkyne demonstrated a complex dependency; rate inhibition and promotion depend on the relative concentration of alkyne to imine. Activation of the aryl C-H bond occurred only in the presence of coordinated alkyne, which suggests operation of a concerted metalation-deprotonation (CMD) mechanism. Small primary isotope effects are consistent with a rate-determining C-H cleavage. Off-cycle olefin isomerization catalyzed by the same Co(-I) active species appears to be responsible for the observed Z-selectivity.
- Suslick, Benjamin A.,Tilley, T. Don
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supporting information
p. 11203 - 11218
(2020/07/08)
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- Activation of Low-Valent, Multiply M-M Bonded Group VI Dimers toward Catalytic Olefin Metathesis via Surface Organometallic Chemistry
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Olefin metathesis is a broadly employed reaction with applications that range from fine chemicals to materials and petrochemicals. The design and investigation of olefin metathesis catalysts have been ongoing for over half a century, with advancements made in terms of activity, stability, and selectivity. Immobilization of organometallic complexes onto solid supports such as silica or alumina is a promising strategy for catalyst heterogenization, often resulting in increased activity and stability. Consequently, a broad range of early transition metal catalysts bearing alkyl, oxide/alkoxide, and amide ligands have been grafted onto silica and their reactivities investigated. Herein, we report a series of silica-supported tungsten and molybdenum dimers (X3MMX3, where M = W and Mo; X = neopentyl, tert-butoxide, and dimethyl amide) and their reactivities toward catalytic olefin metathesis. Dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR), diffuse reflectance infrared Fourier transform (DRIFT), UV resonance Raman, and X-ray absorption (XAS) spectroscopies suggest that upon heterogenization the dimers bind to the surface in a monopodal fashion, with the MM triple bond remaining intact. These structural assignments were further corroborated by density functional theory (DFT) calculations. While the homogeneous dimer counterparts are inert, the supported low-valent alkyl W and Mo dimers become active for the disproportionative self-metathesis of propylene to ethylene and butenes and 4-nonene to 4-octene and 5-decene under mild conditions. The lack of activity observed for the free and supported tert-butoxide and dimethyl amide dimers likely suggests that the neopentyl groups are necessary for the formation of a putative alkylidene active species. The difference in reactivity between the free and supported dimers could be explained either by the lowering of the activation barrier of the complex through the electronic effects of the surface or by site isolation of catalytically relevant reactive intermediates.
- Celik, Gokhan,Chapovetsky, Alon,Delferro, Massimiliano,Dogan, Fulya,Ferrandon, Magali S.,Kaphan, David M.,Khetrapal, Navneet,Kim, Hacksung,Kropf, A. Jeremy,Langeslay, Ryan R.,Perras, Frédéric A.,Pruski, Marek,Sattelberger, Alfred P.,Sharma, Prachi,Wegener, Evan C.,Wen, Jianguo,White, Jacob
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supporting information
p. 1035 - 1045
(2020/05/04)
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- Dehydrogenation of 1-butene with CO2 over VOx supported catalysts
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Butadiene (BD) is an important intermediate in chemical industry and is obtained predominantly from fossil sources. In the future new and sustainable BD sources and synthesis routes might be required to meet the rising demands for this compound. Here, the synthesis of BD from 1-butene in the presence of CO2 was studied using supported vanadium oxide as active compound. Among the tested supports SBA-15 was shown to be the most effective one and a maximum BD yield of 39 % could be achieved. The VOx/SBA-15 catalysts were characterized by complementary methods to obtain insight about the effect of catalyst synthesis and vanadium loadings on the formation of VOx surface structures as well as the catalytic performance. CO2 has a positive impact on the reaction. Coking was considered to be the main reason for the catalyst deactivation and the decreasing BD yield with increasing time on stream.
- Bartling, S.,Eckelt, R.,Iffl?nder, K.,Kreyenschulte, C.,Lund, H.,Steinfeldt, N.,Wotzka, A.
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- Solid-State Molecular Organometallic Catalysis in Gas/Solid Flow (Flow-SMOM) as Demonstrated by Efficient Room Temperature and Pressure 1-Butene Isomerization
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The use of solid-state molecular organometallic chemistry (SMOM-chem) to promote the efficient double bond isomerization of 1-butene to 2-butenes under flow-reactor conditions is reported. Single crystalline catalysts based upon the σ-alkane complexes [Rh(R2PCH2CH2PR2)(η2η2-NBA)][BArF 4] (R = Cy, tBu; NBA = norbornane; ArF = 3,5-(CF3)2C6H3) are prepared by hydrogenation of a norbornadiene precursor. For the tBu-substituted system this results in the loss of long-range order, which can be re-established by addition of 1-butene to the material to form a mixture of [Rh(tBu2PCH2CH2PtBu2)(cis-2-butene)][BArF 4] and [Rh(tBu2PCH2CH2PtBu2)(1-butene)][BArF 4], in an order/disorder/order phase change. Deployment under flow-reactor conditions results in very different on-stream stabilities. With R = Cy rapid deactivation (3 h) to the butadiene complex occurs, [Rh(Cy2PCH2CH2PCy2)(butadiene)][BArF 4], which can be reactivated by simple addition of H2. While the equivalent butadiene complex does not form with R = tBu at 298 K and on-stream conversion is retained up to 90 h, deactivation is suggested to occur via loss of crystallinity of the SMOM catalyst. Both systems operate under the industrially relevant conditions of an isobutene co-feed. cis:trans selectivites for 2-butene are biased in favor of cis for the tBu system and are more leveled for Cy.
- Furfari, Samantha K.,Martínez-Martínez, Antonio J.,Royle, Cameron G.,Suriye, Kongkiat,Weller, Andrew S.
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p. 1984 - 1992
(2020/02/11)
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- Highly Active Gas Phase Organometallic Catalysis Supported within Metal-Organic Framework Pores
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Metal-organic frameworks (MOFs) can act as a platform for the heterogenization of molecular catalysts, providing improved stability, allowing easy catalyst recovery and a route toward structural elucidation of the active catalyst. We have developed a MOF, 1, possessing vacant N,N-chelating sites which are accessible via the porous channels that penetrate the structure. In the present work, cationic rhodium(I) norbornadiene (NBD) and bis(ethylene) (ETH) complexes paired with both noncoordinating and coordinating anions have been incorporated into the N,N-chelation sites of 1 via postsynthetic metalation and facile anion exchange. Exploiting the crystallinity of the host framework, the immobilized Rh(I) complexes were structurally characterized using X-ray crystallography. Ethylene hydrogenation catalysis by 1·[Rh(NBD)]X and 1·[Rh(ETH)2]X (X = Cl and BF4) was studied in the gas phase (2 bar, 46 °C) to reveal that 1·[Rh(ETH)2](BF4) was the most active catalyst (TOF = 64 h-1); the NBD materials and the chloride salt were notably less active. On the basis of these observations, the activity of the Rh(I) bis(ethylene) complexes, 1·[Rh(ETH)2]BF4 and 1·[Rh(ETH)2]Cl, in butene isomerization was also studied using gas-phase NMR spectroscopy. Under one bar of butene at 46 °C, 1·[Rh(ETH)2]BF4 rapidly catalyzes the conversion of 1-butene to 2-butene with a TOF averaging 2000 h-1 over five cycles. Notably, the chloride derivative, 1 [Rh(ETH)2]Cl displays negligible activity in comparison. XPS analysis of the postcatalysis sample, supported by DFT calculations, suggest that the catalytic activity is inhibited by the strong interactions between a Rh(III) allyl hydride intermediate and the chloride anion.
- Peralta, Ricardo A.,Huxley, Michael T.,Evans, Jack D.,Fallon, Thomas,Cao, Haijie,He, Maoxia,Zhao, Xiu Song,Agnoli, Stefano,Sumby, Christopher J.,Doonan, Christian J.
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p. 13533 - 13543
(2020/09/02)
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- Synthesis of 1,3-Butadiene from 1-Butanol on a Porous Ceramic [Fe,Cr]/γ-Al2O3(K,Ce)/α-Al2O3 Catalytic Converter
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Abstract: —A two-stage method was developed for the synthesis of 1,3-butadiene by dehydration of 1-butanol to a mixture of butenes on γ-Al2O3 granules prepared by self-propagating high-temperature synthesis (SHS) followed by dehydrogenation of the butene fraction to 1,3-butadiene using a porous ceramic catalytic SHS converter [Fe,Cr]/γ-Al2O3(K,Ce)/α-Al2O3. The dehydration of 1-butanol to the butene mixture proceeded almost completely at ~100percent selectivity on γ-Al2O3 granules obtained by SHS at 300°C, which is 50 degrees lower than on industrial gamma-alumina granules. The use of an original hybrid catalytic membrane reactor (HCMR) with selective removal of hydrogen from the reaction zone led to a ~1.3-fold increase in the yield of 1,3-butadiene at ultrapure hydrogen extraction of up to 16 mol percent of the total amount of the hydrogen product. The catalytic activity of the system did not decrease after 20 h of experiment, in contrast to its activity in the industrial process, where catalyst regeneration is performed every 8–15 min.
- Dumeignil, F.,Fedotov, A. S.,Heyte, S.,Marinova, M.,Moiseev, I. I.,Paul, S.,Simon, P.,Tsodikov, M. V.,Uvarov, V. I.
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p. 390 - 404
(2020/07/03)
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- Bimetallic Au-Pd alloy nanoparticles supported on MIL-101(Cr) as highly efficient catalysts for selective hydrogenation of 1,3-butadiene
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Gold-palladium (Au-Pd) bimetallic nanoparticle (NP) catalysts supported on MIL-101(Cr) with Au : Pd mole ratios ranging from 1 : 3 to 3 : 1 were prepared through coimpregnation and H2reduction. Au-Pd NPs were homogeneously distributed on the MIL-101(Cr) with mean particle sizes of 5.6 nm. EDS and XPS analyses showed that bimetallic Au-Pd alloys were formed in the Au(2)Pd(1)/MIL-101(Cr). The catalytic performance of the catalysts was explored in the selective 1,3-butadiene hydrogenation at 30-80 °C on a continuous fixed bed flow quartz reactor. The bimetallic Au-Pd alloy particles stabilized by MIL-101(Cr) presented improved catalytic performance. The as-synthesized bimetallic Au(2)Pd(1)/MIL-101(Cr) with 2 : 1 Au : Pd mole ratio showed the best balance between the activity and butene selectivity in the selective 1,3-butadiene hydrogenation. The Au-Pd bimetallic-supported catalysts can be reused in at least three runs. The work affords a reference on the utilization of a MOF and alloy nanoparticles to develop high-efficiency catalysts.
- Guo, Luxia,Jiang, Shuai,Li, Yingjie,Liu, Lili,Tai, Xishi,Yan, Shijuan,Zhou, Xiaojing
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p. 33417 - 33427
(2020/09/21)
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- Deoxygenation of Epoxides with Carbon Monoxide
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The use of carbon monoxide as a direct reducing agent for the deoxygenation of terminal and internal epoxides to the respective olefins is presented. This reaction is homogeneously catalyzed by a carbonyl pincer-iridium(I) complex in combination with a Lewis acid co-catalyst to achieve a pre-activation of the epoxide substrate, as well as the elimination of CO2 from a γ-2-iridabutyrolactone intermediate. Especially terminal alkyl epoxides react smoothly and without significant isomerization to the internal olefins under CO atmosphere in benzene or toluene at 80–120 °C. Detailed investigations reveal a substrate-dependent change in the mechanism for the epoxide C?O bond activation between an oxidative addition under retention of the configuration and an SN2 reaction that leads to an inversion of the configuration.
- Maulbetsch, Theo,Jürgens, Eva,Kunz, Doris
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p. 10634 - 10640
(2020/07/30)
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- Platinum ethylene dimerization catalysts: Diphosphine vs. diimine ancillary ligand effects
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Kinetic and mechanistic studies are presented for the (dfepe)Pt(Me)(NC5F5)+ (dfepe = (C2F5)2PCH2CH2P(C2F5)2) ethylene dimerization catalyst system. New labile complexes (dfepe)PtMe(L)+ (L = NC5F5, C6F5CN, C6F5NH2, C6F5NO2) have been prepared. A general extension to a variety of other chelating diphosphine analogues (PP)Pt(Me)(C2H4)+ has been accessed by methyl abstraction from donor (PP)PtMe2 precursors with Ph3C+B(C6F5)4? in the presence of ethylene to cleanly afford (PP)Pt(Me)(C2H4)+ products. Catalysis studies for these more electron-rich diphosphine systems demonstrate moderate dimerization activity which is uniformly higher than reported for (diimine)Pt(Me)(C2H4)+. In several cases allylic catalyst decomposition products (PP)Pt(η3-C3H4Me)+ have been identified. A DFT study of insertion barriers for diimine and diphosphine systems is presented which suggests that weakening of Pt-ethylene ground state binding by strong-field diphosphine ligands is a major contributing factor to the lower ethylene insertion barriers for PP systems.
- Adams, Jeramie J.,Arulsamy, Navamoney,Basu, Sayanti,Debnath, Suman,Roddick, Dean M.,Schmidt, Bradley M.
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- CATALYST SYSTEMS THAT INCLUDE METAL OXIDE CO-CATALYSTS FOR THE PRODUCTION OF PROPYLENE
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Embodiments of methods of synthesizing a metathesis catalyst system, which include impregnating tungsten oxide on silica support in the presence of a precursor to produce a base catalyst; calcining the base catalyst; impregnating a metal oxide co-catalyst comprising a metal oxide onto the surface of the base catalyst to produce a doped catalyst; and calcining the doped catalyst to produce a metathesis catalyst system. Further embodiments of processes for the production of propylene, which include contacting a hydrocarbon feedstock comprising a mixture of 1-butene and 2-butene with embodiments of the metathesis catalyst system to produce, via metathesis conversion, a product stream comprising propylene.
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Paragraph 0069-0070
(2020/05/02)
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- Intermetallic GaPd2 Thin Films for Selective Hydrogenation of Acetylene
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The preparation of single-phase and catalytically active GaPd2 coatings was accomplished via DC magnetron sputtering using an intermetallic sputter target. Thin and uniform layers were deposited on borosilicate glass, Si(111) and planar as well as micro-structured stainless steel foils. The specimens were examined regarding their phase composition, film morphology and microstructure. Thin films of different layer thickness were catalytically characterized in the semi-hydrogenation of acetylene, which was conducted at 473 K and a feed gas composition of 0.5 vol.percent C2H2, 5 vol.percent H2 as well as 50 vol.percent C2H4 in helium. Pre-reduction of the catalyst was found to be essential to enhance the catalytic selectivity. Sputtered GaPd2 showed a high selectivity of 73 percent for the hydrogenation to ethylene at conversion levels above 80 percent. The surface-specific activity was strongly increased to 8.97 molacetylene·(A0·h)–1 compared to bulk- or nanoscale GaPd2 (1.93 and 0.30 molacetylene·(A0·h)–1, respectively) caused by the high specific surface area of the thin films.
- Zimmermann, René R.,Siebert, Martin,Ibrahimkutty, Shyjumon,Dittmeyer, Roland,Armbrüster, Marc
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p. 1218 - 1226
(2020/06/09)
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- NNNO-Heteroscorpionate nickel (II) and cobalt (II) complexes for ethylene oligomerization: the unprecedented formation of odd carbon number olefins
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The unprecedented observation of odd carbon number olefins is reported during nickel- catalyzed ethylene oligomerization. Two complexes based on Co (II) and Ni (II) with novel tetradentate heteroscorpionate ligand have been synthesized and fully characterized. These complexes showed the ability to oligomerize ethylene upon activation with various organoaluminum compounds (Et2AlCl, Et3Al2Cl3, EtAlCl2, MMAO). Ni (II) based catalytic systems were sufficiently more active (up to 1900 kg·mol (Ni)?1·h?1·atm?1) than Co (II) analogs and have been found to be strongly dependent on the activator composition. The use of PPh3 as an additive to catalytic systems resulted in the increase of activity up to 4,150 kg·mol (Ni)?1·h?1·atm?1 and in the alteration of selectivity. All Ni (II) based systems activated with EtAlCl2 produce up to 5 mol. percent of odd carbon number olefins; two probable mechanisms for their formation are suggested – metathesis and β-alkyl elimination.
- Zubkevich, Sergey V.,Tuskaev, Vladislav A.,Gagieva, Svetlana Ch.,Kayda, Anatoliy S.,Khrustalev, Victor N.,Pavlov, Alexander A.,Zarubin, Dmitry N.,Bulychev, Boris M.
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- Extension of surface organometallic chemistry to metal?organic frameworks: Development of a well-defined single site [(≡Zr? O?)W(=O)(CH2TBu)3] olefin metathesis catalyst
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We report here the first step by step anchoring of a W(≡CtBu)(CH2tBu)3 complex on a highly crystalline and mesoporous MOF, namely Zr-NU-1000, using a Surface Organometallic Chemistry (SOMC) concept and methodology. SOMC allowed us to selectively graft the complex on the Zr6 clusters and characterize the obtained single site material using state of the art experimental methods including extensive solid-state NMR techniques and HAADF-STEM imaging. Further FT?IR spectroscopy revealed the presence of a W=O moiety arising from the in situ reaction of the W≡CtBu functionality with the coordinated water coming from the 8-connected hexanuclear Zr6 clusters. All the steps leading to the final grafted molecular complex have been identified by DFT. The obtained material was tested for gas phase and liquid phase olefin metathesis and exhibited higher catalytic activity than the corresponding catalysts synthesized by different grafting methods. This contribution establishes the importance of applying SOMC to MOF chemistry to get well-defined single site catalyst on MOF inorganic secondary building units, in particular the in situ synthesis of W=O alkyl complexes from their W carbyne analogues.
- Thiam, Zeynabou,Abou-Hamad, Edy,Dereli, Busra,Liu, Lingmei,Emwas, Abdul-Hamid,Ahmad, Rafia,Jiang, Hao,Isah, Abdulrahman Adamu,Ndiaye, Papa Birame,Taoufik, Mostafa,Han, Yu,Cavallo, Luigi,Basset, Jean-Marie,Eddaoudi, Mohamed
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supporting information
p. 16690 - 16703
(2020/11/09)
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- Selective Ethylene Dimerization by Palladium(II) Complexes Bearing a Phosphinoferrocene Sulfonate Ligand
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Palladium(II) complexes featuring the hybrid anionic ligand 1′-(diphenylphosphino)ferrocene-1-sulfonate (L-), viz., trans-(Et3NH)2[Pd(μ-Cl)Me(L-κP)]2 (1), [Pd(Me)(dmap-κN1)(L-κ2O,P)](2; dmap = 4-(dimethylamino)pyridine), and [Pd(η3-allyl)(L-κ2O,P)] (6), were synthesized and together with the previously reported compounds trans-(Et3NH)2[PdCl2(L-κP)2] and [Pd(LCY)(L-κ2O,P)] (LCY = 2-[(dimethylamino-κN)methyl]phenyl-κC1 and 2-[(methylthio-κS)methyl]phenyl-κC1) tested as precatalysts for Pd-catalyzed ethylene dimerization. Only compound 1 gave rise to an active catalyst after activation by sequential halogen removal with Tl[PF6] and Na[BAr′4] (Ar′ = 3,5-bis(trifluoromethyl)phenyl) in chloroform. Thus, the formed catalyst efficiently mediated the dimerization of ethylene showing both good activity (TOF ≈ 95 h-1) and high selectivity for 1-butene (95%) at 21 °C and 30 bar of ethylene pressure. DFT calculations have shown that the dimerization reaction is thermodynamically preferred over the formation of higher oligomers and that O,P-chelate coordination of the phosphinosulfonate ligand in all Pd(II) reaction intermediates is vital for the catalytic process. In particular, the O,P-chelating phosphinoferrocene sulfonate ligand stabilizes and electronically differentiates the reaction intermediates and favors concerted ethyl migration to coordinated ethylene giving rise to 1-butene.
- Zábransky, Martin,Oberhauser, Werner,Manca, Gabriele,Císa?ová, Ivana,?těpni?ka, Petr
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p. 1534 - 1543
(2019/03/19)
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- Ethylene oligomerization promoted by nickel-based catalysts with silicon-bridged diphosphine amine ligands
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A series of nickel complexes [Ni(L1)Br2] (C1), [Ni(L2)Br2] (C2) and [Ni(L3)Br2] (C3) (L1 = N-isopropyl-N-(((diphenylphosphanyl)methyl)dimethylsilyl)-1,1-diphenylphosphanamine, L2 = N-cyclopentyl-N-(((diphenylphosphanyl)methyl)dimethylsilyl)-1,1-diphenylphosphanamine, L3 = N-(2,6-diisopropylphenyl)-N-(((diphenylphosphanyl)methyl)dimethylsilyl)-1,1-diphenylphosphanamine) were synthesized and characterized by elemental analysis, mass spectrometry, spectroscopy and single-crystal X-ray diffraction. L1, L2 and L3 each act as bidentate ligands. Upon activation with ethylaluminum dichloride, these complexes produce efficient catalytic systems for selective dimerization of ethylene to 1-butene, with catalytic activities of 3.45 × 107?g/(molNi·h) and 95.6% butene selectivity containing 87.6% 1-butene fraction.
- Wei, Wei,Yu, Buwei,Alam, Fakhre,Huang, Yongwang,Cheng, Shaoling,Jiang, Tao
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p. 125 - 133
(2018/10/02)
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- Features of Butene-1 Adsorption on H-Beta Zeolite
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Abstract: The adsorption of butene-1 on Beta zeolite (H form) is studied via flow-adsorption calorimetry. Upon feeding a mixture of 2 vol % of butene-1 in nitrogen over the pre-calcined zeolite (500°C) at room temperature, an exothermic effect is observed that is associated with the adsorption and transformations of butene, particularly its isomerization to cis- and trans-butenes-2. The thermal desorption of adsorbed butene?1 results in formation of hydrocarbon products showing that oligomerization proceeds during adsorption. It is found that zeolite pretreated with moist nitrogen adsorbs water up to 9.2 wt %. A?weak exothermic effect is observed when butene-1 is adsorbed on this rehydrated zeolite, due apparently to the physical adsorption of butene-1. When the rehydrated zeolite is held for long periods of time in a stream of a butene/nitrogen mixture, cis-butene-2 is detected at the reactor outlet, indicating the gradual replacement of water with butene-1 on the active sites of zeolite.
- Volnina,Kipnis,Khadziev
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p. 177 - 180
(2019/04/17)
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- Isomerization of 1-Butene to 2-Butenes in the Presence of Acid-Base Catalysts
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The possibility of reaching the equilibrium in structural isomerization of 1-butene on acid-base catalysts in the temperature interval 20°C–100°C was assesed. This reaction can be used for increasing the 2-butene yield and the selectivity of the subsequent conversion of the isomer mixture obtained to alkylate or methyl ethyl ketone. Amberlyst 15 and HZSM-5 (Si/Al = 11.5) were the most active, with the activity of HZSM-5 increasing with the Al content. MgO and Γ-Al2O3 were poorly active. HY zeolites exhibit high initial activity but undergo rapid deactivation. No deactivation of Amberlyst 15 was noted.
- Dubkov,Piryutko,Kharitonov
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p. 924 - 932
(2019/09/03)
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- SHS Membrane for the Dehydrogenation of n-Butanol to Butadienes
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Abstract—: We have synthesized catalytically active membranes based on α- and γ-Al2O3 powders for the dehydration and dehydrogenation of butyl alcohol to butadiene and hydrogen. The open porosity of the samples obtained in this study is 41% in the case of α-Al2O3 and 38% in the case of γ-Al2O3. The open pore size is 4.6–5.1 μm in the α-Al2O3 material and 0.5–0.8 μm in the γ-Al2O3 material. We have implemented a hybrid, membrane–catalytic process for the dehydrogenation of butanol by combining reaction and hydrogen separation steps in a single device. It has been demonstrated that the dehydration of n-butanol on a γ-Al2O3 converter leads to the formation of a butylene fraction with a selectivity of 99.88–100% at a temperature of 300°C, which is 50°C lower than in the case of commercially available gamma-alumina granules. The dehydrogenation of butylene to butadiene on an α-Al2O3 membrane with selective hydrogen removal from the reaction zone has made it possible to raise the 1,3-butadiene output from 16.5 to 22.6 L/(h gact. comp.), with the degree of ultrapure hydrogen extraction reaching ~16%. After the experiment was run for 20 h, no decrease in the catalytic activity of the system was detected, as distinct from commercial solutions, in which a regeneration step is necessary every 8–15 min.
- Uvarov,Alymov,Loryan,Shustov,Fedotov,Tsodikov
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p. 798 - 802
(2019/09/09)
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- Electrophilic Organoiridium(III) Pincer Complexes on Sulfated Zirconia for Hydrocarbon Activation and Functionalization
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Single-site supported organometallic catalysts bring together the favorable aspects of homogeneous and heterogeneous catalysis while offering opportunities to investigate the impact of metal-support interactions on reactivity. We report a (dmPhebox)Ir(III) (dmPhebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) complex chemisorbed on sulfated zirconia, the molecular precursor for which was previously applied to hydrocarbon functionalization. Spectroscopic methods such as diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS), dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) spectroscopy, and X-ray absorption spectroscopy (XAS) were used to characterize the supported species. Tetrabutylammonium acetate was found to remove the organometallic species from the surface, enabling solution-phase analytical techniques in conjunction with traditional surface methods. Cationic character was imparted to the iridium center by its grafting onto sulfated zirconia, imbuing high levels of activity in electrophilic C-H bond functionalization reactions such as the stoichiometric dehydrogenation of alkanes, with density functional theory (DFT) calculations showing a lower barrier for β-H elimination. Catalytic hydrogenation of olefins was also facilitated by the sulfated zirconia-supported (dmPhebox)Ir(III) complex, while the homologous complex on silica was inactive under comparable conditions.
- Syed, Zoha H.,Kaphan, David M.,Perras, Frédéric A.,Pruski, Marek,Ferrandon, Magali S.,Wegener, Evan C.,Celik, Gokhan,Wen, Jianguo,Liu, Cong,Dogan, Fulya,Goldberg, Karen I.,Delferro, Massimiliano
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supporting information
p. 6325 - 6337
(2019/04/25)
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- Plant-mediated synthesis of AgPd/γ-Al2O3 catalysts for selective hydrogenation of 1,3-butadiene at low temperature
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In this dissertation, silver-palladium (AgPd) bimetallic nanoparticles were synthesized by a green biosynthesis method using Cacumen platycladi leaf extract, which provided both reductive and protective agents. Then the supported AgPd/γ-Al2O3 catalysts were obtained by the sol-immobilization method, and the as-biosynthesized AgPd/γ-Al2O3 catalysts with different particle sizes and compositions were used for 1,3-butadiene hydrogenation. Optimization of the catalyst preparation and selective hydrogenation parameters was performed. Using the catalyst, a 1,3-butadiene conversion of 98.2% and a butene selectivity of 88.1% were achieved. The durability experiment of AgPd/γ-Al2O3 catalysts was carried out for 50 h, and the activity decreased slightly and the selectivity almost remains the same during the 50 h, indicating their remarkable stability. The results of TEM and TG analysis showed that the size of the AgPd nanoparticles was nearly the same before and after the durability experiment, and the existence of residual biomolecules on the catalyst surface helped to prevent agglomeration and modification of the surface properties of the catalyst, which would promote desorption of the product, and then avoid intensifying the level of further hydrogenation.
- Lu, Fenfen,Sun, Daohua,Jiang, Xia
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p. 13891 - 13898
(2019/09/16)
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- Controlling catalytic activity and selectivity for partial hydrogenation by tuning the environment around active sites in iridium complexes bonded to supports
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Single-site Ir(CO)2 complexes bonded to high-surface-area metal oxide supports, SiO2, TiO2, Fe2O3, CeO2, MgO, and La2O3, were synthesized by chemisorption of Ir(CO)2(acac) (acac = acetylacetonate) followed by coating with each of the following ionic liquids (ILs): 1-n-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4], 1-n-butyl-3-methylimidazolium acetate, [BMIM][Ac], and 1-(3-cyanopropyl)-3-methylimidazolium dicyanamide, [CPMIM][DCA]. Extended X-ray absorption fine structure spectroscopy showed that site-isolated iridium was bonded to oxygen atoms of the support. Electron densities on the iridium enveloped by each IL sheath/support combination were characterized by carbonyl infrared spectroscopy of the iridium gem-dicarbonyls and by X-ray absorption near-edge structure data. The electron-donor/acceptor tendencies of both the support and IL determine the activity and selectivity of the catalysts for the hydrogenation of 1,3-butadiene, with electron-rich iridium being selective for partial hydrogenation. The results resolve the effects of the IL and support as ligands; for example, the effect of the IL becomes dominant when the support has a weak electron-donor character. The combined effects of supports and ILs as ligands offer broad opportunities for tuning catalytic properties of supported metal catalysts.
- Babucci, Melike,Fang, Chia-Yu,Perez-Aguilar, Jorge E.,Hoffman, Adam S.,Boubnov, Alexey,Guan, Erjia,Bare, Simon R.,Gates, Bruce C.,Uzun, Alper
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p. 2623 - 2632
(2019/03/05)
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- BUTENE CONVERSION METHOD AND MONOFLUOROBUTANE PURIFICATION METHOD
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Provided is an industrially simple and cheap method for efficiently removing butene from crude monofluorobutane containing butene without causing substantial decomposition, transformation, or the like of the monofluorobutane. In a provided monofluorobutane purification method, crude monofluorobutane containing butene is brought into contact with trihalomethane in the presence of an alkali aqueous solution to convert the butene to a compound having a higher boiling point than the monofluorobutane, water is subsequently added to a reaction mixture obtained thereby to dissolve a produced salt, an organic layer is separated, and then the separated organic layer is purified by distillation.
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-
Paragraph 0107; 0108; 0109; 0110
(2019/06/20)
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- Nickel(II) complexes with tripodal NNN ligands as homogenous and supported catalysts for ethylene oligomerization
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Four new coordination compounds of nickel (II) with derivatives of N,N-bis(pyrazol-1-ylmethyl)propylamine were synthesized; their composition and structure were confirmed with IR-spectroscopy and elemental analysis. The structures of products 13 and 15 were unambiguously established in an X-ray diffraction study. Compounds 13 and 15 crystallize in the orthorhombic space groups Pna21 and P212121 correspondingly and represent a monomeric octahedral nickel complexes, that are typical for tridentate scorpion-type ligands. New method for immobilization of nickel complexes with derivatives of N,N-bis(pyrazol-1-ylmethyl)propylamine on silica gel modified with aminopropyl groups was proposed. The EXAFS/XANES analysis indicated that Ni atom in the supported complexes adopt almost octahedral geometry, being partly surrounded by nitrogen atoms from organic ligand and partly grafted to silica surface through silanol groups, with Br? in outer coordination sphere. Both the original and the supported complexes, when activated with Et2AlCl or Et3Al2Cl3, catalyze ethylene oligomerization with the predominant formation of butene isomers. Generally, the immobilized complexes show higher activity and better selectivity towards 1-butene formation.
- Tuskaev, Vladislav A.,Zubkevich, Sergei V.,Saracheno, Daniele,Gagieva, Svetlana Ch.,Dorovatovskii, Pavel V.,Kononova, Elena G.,Khrustalev, Victor N.,Zarubin, Dmitry N.,Bulychev, Boris M.,Kissin, Yury V.
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- Remarkably enhanced performance of the metathesis reaction of ethylene and 1-butene to propene using one-step prepared W-MCM-41 catalysts
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Highly dispersed tungsten species with an isolated tetrahedral WOx species structure are substantially beneficial for the metathesis reaction of ethylene and 1-butene to propene. The conventional impregnation method always leads to the formation of inactive crystalline WO3 thereby notably decreasing the amount of active sites. In this study, we synthesized a highly dispersed W-MCM-41 catalyst using the one-step precipitation method with a Si/W ratio of 30. The prepared catalyst showed excellent catalytic performance with a 1-butene conversion of 92.7% and a propene selectivity of 80.8%. In contrast, the impregnated catalyst with the same W loading as the one-step precipitation method resulted in a much lower 1-butene conversion of 76.5% and propene selectivity of 34.1%. Various characterization techniques including XRD, XPS, ICP-OES, UV-vis DRS, TEM, and Raman spectroscopy were applied to confirm that the one-step precipitation method can efficiently prepare well-dispersed W-MCM-41 catalysts with the desired structure in spite of the fact that the ideal dispersive structure was strongly dependent of the Si/W ratio and stirring time of the reaction mixture of tungstic acid and TEOS. In addition, the introduction of an upstream catalyst onto the W-MCM-41 catalyst could not obviously improve the 1-butene conversion and propene selectivity, which might be due to fast 1-butene isomerization easily occurring on the abundant Si-OH of the W-MCM-41 catalyst. This work provides new insights for the design of metathesis catalysts and reaction processes to efficiently convert ethylene and 1-butene into propene.
- Wang, Changji,Jiang, Feng,Zuo, Guangzheng,Liu, Bing,Li, Hanxu,Liu, Xiaohao
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p. 40618 - 40627
(2019/12/25)
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- METHOD FOR PRODUCING FLUORINATED HYDROCARBONS
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Provided is a method for industrially advantageously producing a fluorinated hydrocarbon (3). The disclosed method for producing a fluorinated hydrocarbon represented by formula (3) includes bringing into contact, in a hydrocarbon-based solvent, a secondary or tertiary ether compound represented by formula (1) below with an acid fluoride represented by formula (2) in the presence of lithium salt or sodium salt (in the formulae, R1 and R2 each represent a C1-3 alkyl, and R1 and R2 may be bonded to each other to form a ring structure; R3 represents a hydrogen atom, methyl, or ethyl; and R4 and R5 each represent methyl or ethyl).
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-
Paragraph 0108; 0110; 0112-0118; 0121-0124; 0129; 0132
(2020/01/12)
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- Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdHx
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Controllable synthesis of well-defined supported intermetallic catalysts is desirable because of their unique properties in physical chemistry. To accurately pinpoint the evolution of such materials at an atomic-scale, especially clarification of the initial state under a particular chemical environment, will facilitate rational design and optimal synthesis of such catalysts. The dynamic formation of a ZnO-supported PdZn catalyst is presented, whereby detailed analyses of in situ transmission electron microscopy, electron energy-loss spectroscopy, and in situ X-ray diffraction are combined to form a nanoscale understanding of PdZn phase transitions under realistic catalytic conditions. Remarkably, introduction of atoms (H and Zn in sequence) into the Pd matrix was initially observed. The resultant PdHx is an intermediate phase in the intermetallic formation process. The evolution of PdHx in the PdZn catalyst initializes at the PdHx/ZnO interfaces, and proceeds along the PdHx ?111? direction.
- Niu, Yiming,Liu, Xi,Wang, Yongzhao,Zhou, Song,Lv, Zhengang,Zhang, Liyun,Shi, Wen,Li, Yongwang,Zhang, Wei,Su, Dang Sheng,Zhang, Bingsen
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supporting information
p. 4232 - 4237
(2019/02/16)
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- Continuous-Flow Alkane Dehydrogenation by Supported Pincer-Ligated Iridium Catalysts at Elevated Temperatures
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Pincer-ligated iridium complexes of the form [Ir(R4PCP)L] (R4PCP = κ3-C6H3-2,6-(XPR2)2; X = CH2, O; R = tBu, iPr) are efficient homogeneous alkane dehydrogenation catalysts that have been reported to be highly active at temperatures of 240 °C or below. In this work, silica-supported [Ir(C2H4)(p-tBu2PO-tBu4POCOP)] (1/SiO2) was used to study a model continuous-flow gas-phase acceptorless alkane dehydrogenation system. This particular supported framework is thermally stable at temperatures up to 340 °C, 100 °C above the highest temperature at which analogous homogeneous complexes have been reported to show stable activity, with observed butane dehydrogenation rates of ca. 80 molbutenes molcat.-1 h-1. Solid-state 31P MAS NMR and ATR IR are used to demonstrate that the backbone pincer ligand remains intact and coordinated at 340 °C. The complex is fully converted to [Ir(CO)(p-tBu2PO-tBu4POCOP)] (3/SiO2) above 300 °C. 3/SiO2 is observed to be catalytically active at the higher temperatures tested, and reaction rates are comparable to those of 1/SiO2. 3/SiO2 and 1/SiO2 act as resting states for the active 14-electron fragment, through dissociation of the CO or olefin ligand, respectively. Given that 3/SiO2 is air resistant at ambient temperature and is structurally stable and catalytically active at elevated temperatures, it is a suitable candidate as a catalyst for the highly endothermic acceptorless dehydrogenation of alkanes.
- Sheludko, Boris,Cunningham, Molly T.,Goldman, Alan S.,Celik, Fuat E.
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p. 7828 - 7841
(2018/07/25)
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- Ethylene Oligomerization to Select Oligomers on Ni-ETS-10
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The oligomerization of short alkenes (ethylene and propylene) can be used for producing commodity chemicals. Various catalysts have been used for alkene oligomerization, among which ordered microporous catalysts are thermally and mechanically stable and are already established for large-scale industrial applications. In this work, we demonstrate ethylene oligomerization reaction on a microporous titanosilicate ETS-10 (Engelhard Titanosiliate-10) exchanged with Ni2+ (Ni-ETS-10). We demonstrate a template-free and fluoride-free ETS-10 synthesis method that does not produce impurities commonly seen in hydrothermal ETS-10 synthesis. Ni-ETS-10 showed high C2 conversion rate, high selectivity to C4 and high stability comparing to other microporous catalysts investigated in this work for ethylene oligomerization reaction.
- Thakkar, Jay,Yin, Xinyang,Zhang, Xueyi
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p. 4234 - 4237
(2018/09/14)
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- Beyond the Active Site: Tuning the Activity and Selectivity of a Metal-Organic Framework-Supported Ni Catalyst for Ethylene Dimerization
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To modify its steric and electronic properties as a support for heterogeneous catalysts, electron-withdrawing and electron-donating ligands, hexafluoroacetylacetonate (Facac-) and acetylacetonate (Acac-), were introduced to the metal-organic framework (MOF), NU-1000, via a process akin to atomic layer deposition (ALD). In the absence of Facac- or Acac-, NU-1000-supported, AIM-installed Ni(II) sites yield a mixture of C4, C6, C8, and polymeric products in ethylene oligomerization. (AIM = ALD-like deposition in MOFs). In contrast, both Ni-Facac-AIM-NU-1000 and Ni-Acac-AIM-NU-1000 exhibit quantitative catalytic selectivity for C4 species. Experimental findings are supported by density functional theory calculations, which show increases in the activation barrier for the C-C coupling step, due mainly to rearrangement of the siting of Facac- or Acac- to partially ligate added nickel. The results illustrate the important role of structure-tuning support modifiers in controlling the activity of MOF-sited heterogeneous catalysts and in engendering catalytic selectivity. The results also illustrate the ease with which crystallographically well-defined modifications of the catalyst support can be introduced when the node-coordinating molecular modifier is delivered via the vapor phase.
- Liu, Jian,Ye, Jingyun,Li, Zhanyong,Otake, Ken-Ichi,Liao, Yijun,Peters, Aaron W.,Noh, Hyunho,Truhlar, Donald G.,Gagliardi, Laura,Cramer, Christopher J.,Farha, Omar K.,Hupp, Joseph T.
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supporting information
p. 11174 - 11178
(2018/09/12)
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- Nickel-based ethylene oligomerization catalysts supported by PNSiP ligands
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A series of nickel (II) complexes bearing silicon bridged diphosphines ligands (PNSiP) have been synthesized and characterized. All nickel precatalysts, activated with ethylaluminum dichloride (EtAlCl2), exhibited moderate to high activities for ethylene dimerization to butylene. The in situ nickel precatalysts formed by mixing N-cyclopentyl-N-((diphenylphosphanyl)dimethylsilyl)-1,1-diphenylphosphanamine (L2) with NiBr2(DME) showed high catalytic activity (2.40 × 108 g/(molNi·h)) and high product selectivity (88.6%) towards butene using methylcyclohexane as solvent at 1.0?MPa ethylene pressure and 45°C temperature, no polyethylene(PE) was observed. Ligand backbone tuning of PNSiP-based catalytic systems help in precise understanding of steric bulk variation effects on catalytic performance.
- Huang, Yongwang,Zhang, Le,Wei, Wei,Alam, Fakhre,Jiang, Tao
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p. 363 - 368
(2018/02/06)
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- Activation of Methyltrioxorhenium for Olefin Metathesis in a Zirconium-Based Metal-Organic Framework
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The zirconium nodes of the metal-organic framework (MOF) known as NU-1000 serve as competent supports for the activation of methyltrioxorhenium (MTO) toward olefin metathesis. Itself inactive for olefin metathesis, MTO becomes an active catalyst only when immobilized on the strongly acidic Lewis acid sites of dehydrated NU-1000. Uptake of MTO at the dehydrated secondary building units (SBUs) occurs rapidly and quantitatively to produce a catalyst active in both gas- and liquid-phase processes. These results demonstrate for the first time the utility of MOF SBUs for olefin metathesis, an academically and industrially relevant transformation.
- Korzyński, Maciej D.,Consoli, Daniel F.,Zhang, Shiran,Román-Leshkov, Yuriy,Dincǎ, Mircea
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supporting information
p. 6956 - 6960
(2018/05/23)
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- Enhanced Metathesis Activity and Stability of Methyltrioxorhenium on a Mostly Amorphous Alumina: Role of the Local Grafting Environment
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Inorganic oxides play a crucial role in the activation of atomically dispersed metal oxides for catalytic olefin transformations, but the inefficient activation processes remain poorly understood. Activation of methyltrioxorhenium (MTO) for propene metathesis via its deposition on the surface of ?3-Al2O3 typically results in 2O3) results in ca. 4× more activity and at least 10× more productivity. On both types of alumina, metathesis is initiated only at specific sites, whose availability limits the catalytic activity. While the two aluminas have similar total numbers of Lewis acid sites, the less crystalline support activates twice as many grafted MTO sites. Interestingly, a-Al2O3 has nearly double the number of strong Lewis acid sites. However, the number of active sites is ca. 10× lower than the total number of strong Lewis acid sites, and metathesis proceeds even when most are occupied by pyridine. DQSQ and D-HMQC 1H and 27Al solid-state NMR reveal that many Lewis acid sites are co-located with surface hydroxyl groups, which prevent activation and/or cause rapid deactivation. Undercoordinated Al sites on dominant (110) facets, which retain hydroxyl groups under catalyst preparation conditions, are therefore unlikely to lead to stable active sites. In contrast, the minor (100) facets of ?3-Al2O3, which are completely dehydroxylated, contain strongly Lewis-acidic five-coordinate Al sites that are necessarily remote from surface hydroxyl groups. Such sites, which are relatively more abundant on less well-crystallized aluminas, are inferred to be responsible for generating stable metathesis sites.
- Zhang, Fan,Szeto, Kai C.,Taoufik, Mostafa,Delevoye, Laurent,Gauvin, Régis M.,Scott, Susannah L.
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supporting information
p. 13854 - 13868
(2018/10/24)
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- New synthetic approach towards well-defined silica supported tungsten bis-oxo, active catalysts for olefin metathesis
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A well-defined bis-oxo bisiloxy tungsten surface species has been prepared by a new synthetic non-aqueous approach. The reaction of [W(O[dbnd])(OtBu)4] with the silica surface dehydroxylated at 200 °C proceeds by W–O cleavage with concomitant tBuOH release, leading to bigrafted [([tbnd]SiO)2W([dbnd]O)(OtBu)2]. Upon heating at 300 °C, it converts into the bis-oxo derivative [([tbnd]SiO)2W([dbnd]O)2]. Without co-catalyst, this material demonstrated high, sustained activity and selectivity in propene metathesis. This emphasizes the importance of the design of robust bis-oxo catalysts by Surface Organometallic Chemistry and represents a significant step to understand and mimic the active species of the industrial WO3/SiO2 system.
- Larabi, Cherif,Merle, Nicolas,Le Quéméner, Frederic,Rouge, Pascal,Berrier, Elise,Gauvin, Régis M.,Le Roux, Erwan,de Mallmann, Aimery,Szeto, Kai C.,Taoufik, Mostafa
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- Integrated conversion of 1-butanol to 1,3-butadiene
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Renewed interest in production of 1,3-butadiene from non-petroleum sources has motivated research into novel production routes. In this study, we investigated an integrated process comprising 1-butanol dehydration over a γ-Al2O3 catalyst to produce a mixture of linear butenes, coupled with a downstream K-doped Cr2O3/Al2O3 catalyst to convert the butenes into butadiene. Linear butene yields greater than 90% are achievable at 360 °C in the dehydration step, and single-pass 1,3-butadiene yields greater than 40% are achieved from 1-butene in a N2 atmosphere in the dehydrogenation step. In the integrated process, 1,3-butadiene yields are 10-15%. In all cases, linear C4 selectivity is greater than 90%, suggesting that 1,3-butadiene yields could be significantly improved in a recycle reactor. Doping the Cr2O3 catalyst with different metals to promote H2 consumption in a CO2 atmosphere did not have a large effect on catalyst performance compared to an undoped Cr2O3 catalyst, although doping with K in an N2-diluted atmosphere and with Ni in a CO2-enriched atmosphere showed slight improvement. In contrast, doping with K and Ca in a CO2-enriched atmosphere showed slightly decreased performance. Similarly, employing a CO2-enriched atmosphere in general did not improve 1,3-butadiene yield or selectivity compared to reactions performed in N2. Overall, this study suggests that an integrated dehydration/dehydrogenation process to convert 1-butanol into 1,3-butadiene could be feasible with further catalyst and process development.
- Kruger, Jacob S.,Dong, Tao,Beckham, Gregg T.,Biddy, Mary J.
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p. 24068 - 24074
(2018/07/13)
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- INTEGRATED METHOD FOR PRODUCING BUTADIENE FROM BUTANOL
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The invention relates to a thermally-integrated method for producing butadiene from butanol that comprises at least the following steps: a) Dehydration of butanol, fed by a dehydration feed that is formed from at least said n-butanol feedstock that is diluted with at least a portion of the purified water effluent that is obtained from step c), leading to a butene effluent in at least one reactor, in the presence of a catalyst that comprises an alumina,b) Oxidizing dehydrogenation of said butene effluent, diluted with at least a portion of the purified water effluent that is obtained from step c), into butadiene, with said butene effluent not having undergone any treatment following the dehydration step a),c) Separation of the effluent that is obtained from step b) into at least one butadiene effluent and one purified water effluent.
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Paragraph 0082-0090
(2018/10/04)
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- Chemoselective Hydrogenation with Supported Organoplatinum(IV) Catalyst on Zn(II)-Modified Silica
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Well-defined organoplatinum(IV) sites were grafted on a Zn(II)-modified SiO2 support via surface organometallic chemistry in toluene at room temperature. Solid-state spectroscopies including XAS, DRIFTS, DRUV-vis, and solid-state (SS) NMR enhanced by dynamic nuclear polarization (DNP), as well as TPR-H2 and TEM techniques revealed highly dispersed (methylcyclopentadienyl)methylplatinum(IV) sites on the surface ((MeCp)PtMe/Zn/SiO2, 1). In addition, computational modeling suggests that the surface reaction of (MeCp)PtMe3 with Zn(II)-modified SiO2 support is thermodynamically favorable (ΔG = -12.4 kcal/mol), likely due to the increased acidity of the hydroxyl group, as indicated by NH3-TPD and DNP-enhanced 17O{1H} SSNMR. In situ DRIFTS and XAS hydrogenation experiments reveal the probable formation of a surface Pt(IV)-H upon hydrogenolysis of Pt-Me groups. The heterogenized organoplatinum(IV)-hydride sites catalyze the selective partial hydrogenation of 1,3-butadiene to butenes (up to 95%) and the reduction of nitrobenzene derivatives to anilines (up to 99%) with excellent tolerance of reduction-sensitive functional groups (olefin, carbonyl, nitrile, halogens) under mild reaction conditions.
- Camacho-Bunquin, Jeffrey,Ferrandon, Magali,Sohn, Hyuntae,Yang, Dali,Liu, Cong,Ignacio-De Leon, Patricia Anne,Perras, Frédéric A.,Pruski, Marek,Stair, Peter C.,Delferro, Massimiliano
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p. 3940 - 3951
(2018/03/29)
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- An ordinary nickel catalyst becomes completely selective for partial hydrogenation of 1,3-butadiene when coated with tributyl(methyl)phosphonium methyl sulfate
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Performance of an ordinary supported nickel catalyst was tuned to reach an almost complete selectivity for partial hydrogenation of 1,3-butadiene by coating it with a phosphonium-type ionic liquid (IL), tributyl(methyl)phosphonium methyl sulfate, [P4441][MeSO4]. Thanks to high chemical and thermal stability of [P4441][MeSO4], the reaction conditions could be pre-optimized for high partial hydrogenation performance before the deposition of the IL coating. When the catalyst was coated with IL, it provided a total butene selectivity of 99.5 ± 0.2%, a record high partial hydrogenation selectivity ever reported for a nickel-based catalyst. X-ray photoelectron spectroscopy results illustrated that the IL donates electrons to nickel sites and makes them selective for partial hydrogenation. The conductor like screening model for realistic solvents (COSMO-RS) calculations indicated that the IL coating also exerts a filter effect, which helps to maintain this high partial hydrogenation selectivity at all conversion levels.
- Jalal, Ahsan,Uzun, Alper
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p. 321 - 326
(2018/06/29)
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- MULTIMETALLIC CATALYSTS FOR SELECTIVE HYDROGENATION OF DIENES AND ACETYLENES, AND PURIFICATION OF OLEFIN FEEDSTOCKS
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A catalyst for hydrogenation reaction processes includes an oxide substrate surface, a MOx promoter, where M is a transition metal or main group elemental oxide, the promoter being deposited on the substrate, and a platinum group catalytic metal.
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Paragraph 0025-0026
(2018/10/30)
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- Production of conjugated diene (by machine translation)
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[A] can be obtained efficiently from the alkanes of a conjugated diene, a conjugated diene or a new method of manufacturing. [Solution] water containing alkane dehydrogenation catalyst is contacted with a first raw material gas first, olefin-containing gas comprises a first step of obtaining first, second product gas and water are mixed with the second material gas is contacted with a second hydrogenation catalyst, to obtain a second product gas containing a conjugated diene and a second process, comprising, the molar ratio of water to hydrocarbon in the second material gas, a raw material gas to hydrocarbon molar ratio greater than the first water, production of conjugated diene. [Drawing] no (by machine translation)
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Paragraph 0090; 0094
(2018/02/23)
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- METHOD FOR PRODUCING UNSATURATED HYDROCARBON
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PROBLEM TO BE SOLVED: To provide a production method capable of obtaining an unsaturated hydrocarbon with excellent production efficiency, which causes less deposition of coke on a catalyst and can maintain good reaction efficiency for a long time. SOLUTION: There is provided a method for producing an unsaturated hydrocarbon, which comprises a step of bringing a raw material gas containing an alkane into contact with a dehydrogenation catalyst to obtain a product gas containing at least one unsaturated hydrocarbon selected from the group consisting of an olefin and a conjugated diene, wherein the dehydrogenation catalyst contains at least one addition element selected from the group consisting of Na, K and Ca, Al, Mg, a Group 14 metal element and Pt and the content of the addition element is 0.05 mass% or more and 0.70 mass% or less based on the total amount of the dehydrogenation catalyst. SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0094; 0095; 0100; 0102; 0104; 0106; 0108; 0110
(2018/09/21)
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- METHOD FOR PRODUCING CONJUGATED DIENE
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PROBLEM TO BE SOLVED: To provide a production method capable of obtaining a conjugated diene with excellent production efficiency, which causes less deposition of coke on a catalyst and can maintain good reaction efficiency for a long time. SOLUTION: There is provided a method for producing a conjugated diene, which comprises a step of bringing a raw material gas containing olefin into contact with a dehydrogenation catalyst to obtain a product gas containing a conjugated diene, wherein the dehydrogenation catalyst contains Si, a Group 14 metal element and Pt and the molar ratio of the Group 14 metal element to Pt in the dehydrogenation catalyst is 1.3 or more and 3 or less. SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0096; 0097; 0098
(2018/10/16)
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