- Boosting the synthesis of value-added aromatics directly from syngasviaa Cr2O3and Ga doped zeolite capsule catalyst
-
Even though the transformation of syngas into aromatics has been realizedviaa methanol-mediated tandem process, the low product yield is still the bottleneck, limiting the industrial application of this technology. Herein, a tailor-made zeolite capsule catalyst with Ga doping and SiO2coating was combined with the methanol synthesis catalyst Cr2O3to boost the synthesis of value-added aromatics, especiallypara-xylene, from syngas. Multiple characterization studies, control experiments, and density functional theory (DFT) calculation results clarified that Ga doped zeolites with strong CO adsorption capability facilitated the transformation of the reaction intermediate methanol by optimizing the first C-C coupling step under a high-pressure CO atmosphere, thereby driving the reaction forward for aromatics synthesis. This work not only reveals the synergistic catalytic network in the tandem process but also sheds new light on principles for the rational design of a catalyst in terms of oriented conversion of syngas.
- Gao, Weizhe,Gao, Xinhua,Ma, Qingxiang,Tsubaki, Noritatsu,Wang, Kangzhou,Wang, Yang,Wu, Mingbo,Yang, Guohui,Zhang, Baizhang,Zhang, Peipei,Zhao, Heng
-
-
Read Online
- A Facile Solid-Phase Route to Renewable Aromatic Chemicals from Biobased Furanics
-
Renewable aromatics can be conveniently synthesized from furanics by introducing an intermediate hydrogenation step in the Diels-Alder (DA) aromatization route, to effectively block retro-DA activity. Aromatization of the hydrogenated DA adducts requires tandem catalysis, using a metal-based dehydrogenation catalyst and solid acid dehydration catalyst in toluene. Herein it is demonstrated that the hydrogenated DA adducts can instead be conveniently converted into renewable aromatics with up to 80 % selectivity in a solid-phase reaction with shorter reaction times using only an acidic zeolite, that is, without solvent or dehydrogenation catalyst. Hydrogenated adducts from diene/dienophile combinations of (methylated) furans with maleic anhydride are efficiently converted into renewable aromatics with this new route. The zeolite H-Y was found to perform the best and can be easily reused after calcination. Just heat and tumble: Furanics-derived hydrogenated Diels-Alder adducts can be conveniently converted, over acidic zeolites, into renewable aromatics using a solid-phase conversion strategy. The zeolite H-Y was found to perform the best and can be easily reused after calcination.
- Thiyagarajan, Shanmugam,Genuino, Homer C.,Van Der Waal, Jan C.,De Jong, Ed,Weckhuysen, Bert M.,Van Haveren, Jacco,Bruijnincx, Pieter C. A.,Van Es, Daan S.
-
-
Read Online
- Vapor phase alkylation of toluene using various alcohols over H 3PO4/MCM-41 catalyst: Influence of reaction parameters on selectivity and conversion
-
A mesoporous MCM-41 molecular sieve material with a molar ratio of SiO 2/Al2 O3 = 70 and loaded with H3 PO4 was used as a catalyst for the alkylation of toluene, using various alcohols, namely methanol, iso-propanol, and tert-butanol, as alkylating agents. Para-alkylated toluene was the predominant product, formation of which was enhanced by moderate temperature, low amounts of the alkylating agents in the feed, and high carrier gas flow rate. Time on stream was found to exert a profound effect on the selectivity and conversion to the different products. TUeBITAK.
- Abbaspourrad, Alireza,Kalbasi, Roozbeh Javad,Zamani, Farzad
-
-
Read Online
- Continuous process for the production of aromatic hydrocarbons from n-hexane and C5+ natural gas liquid over Pd-loaded ZSM-5 zeolite
-
A continuous process for the production of aromatic hydrocarbons from n-hexane and C5+ natural gas liquid (C5+ NGL) over Pd-loaded ZSM-5 zeolite in a tubular reactor was developed. The optimal conditions for continuous aromatization of n-hexane and C5+ NGL were found at 400°C reaction temperature and 0.4 cm3/min reactant feeding rate, employing ZSM-5 (0.5% Pd content) as a catalyst; under these conditions, n-hexane conversion and aromatic contents in reaction product were found to be 99.7% and 92.3%, respectively. GC and GC/MS analysis revealed that this continuous process for n-hexane aromatization yielded both benzene derivatives and naphthalene derivatives, including benzene (5.7%), toluene (23.6%), xylenes (25.0%), 4-ethyltoluene (3.5%), 1,3,5-trimethylbenzene (4.9%), 1-methylnaphthalene (4.3%), and 1,5-dimethylnaphthalene (3.6%). Under the same reaction conditions, C5+ NGL gave 94.3% conversion and 92.6% aromatic contents in reaction product. The composition of product included benzene (8.1%), toluene (23.3%), xylenes (22.8%), 4-ethyltoluene (4.3%), 1,3,5-trimethylbenzene (3.7%), 1-methylnaphthalene (4.1%), and 1,5-dimethylnaphthalene (2.9%).
- Suwanprasop, Somsaluay,Khamnuansiri, Pharkpoom,Nhujak, Thumnoon,Roengsumran, Sophon,Petsom, Amorn
-
-
Read Online
- Post-synthesis modification of TUN zeolite: Textural, acidic and catalytic properties
-
Dealumination, desilication and silylation of TUN zeolite was investigated and related to the catalytic behavior in toluene disproportionation and its alkylation with isopropyl alcohol. Only negligible concentration of acid sites was identified on the "external" surface of parent TUN zeolite and this concentration increased with increasing desilication. Silylation resulted in channel narrowing and probably some plugging. As a result, significant increase in the para-selectivity in toluene disproportionation and its alkylation with isopropyl alcohol was achieved. No changes in toluene conversion were observed for all parent and modified samples in toluene alkylation confirming diffusion and transport of products as the rate determining step in 10-ring zeolites. Selectivity to cymenes and p-cymene decreased with dealumination as well as desilication. In contrast, silylation increased both cymene (80%) and p-cymene (90%) selectivity in toluene alkylation.
- Kub, Martin,?ilková, Nadě?da,?ejka, Ji?í
-
-
Read Online
- Destruction of halogenated hydrocarbons with solvated electrons in the presence of water
-
Model halogenated aromatic and aliphatic hydrocarbons and halogenated phenols were dehalogenated in seconds by solvated electrons generated from sodium in both anhydrous liquid ammonia and ammonia/water solutions. The minimum sodium required to completely dehalogenate these model compounds was determined by increasing the Na/substrate ratio until halogen loss was complete. Minimum sodium consumptions were determined in both anhydrous liquid ammonia and with a (5, 20, 50-fold molar excess of water per mole of halide). While more Na was consumed in the presence of water, these dehalogenations were still efficient when a 50-fold water excess was present. Dehalogenation is faster than competiting reactions with water. CCl4 and CH3CCl3 in the presence of a stoichiometric deficiency of sodium produced only CH4 and CH3CH3 and recovered CCl44 or CH3CCl3, respectively. No partially dechlorinated products were detected, indicating dechlorination was diffusion controlled. Na consumption per chlorine removed (as NaCl) was lower than that of Li, K or Ca and this advantage increased in the presence of water. Na consumption was lower using Na chunks instead of a thin Na mirror. Chloroaromatic compounds gave the parent aromatic hydrocarbon and aminated products in anhydrous ammonia but aminated products did not form when water was present. (C) 2000 Elsevier Science Ltd.
- Sun, Guang-Ri,He, Jin-Bao,Pittman Jr., Charles U.
-
-
Read Online
- Pyrolysis of 3-carene: Experiment, Theory and Modeling
-
Thermal decomposition studies of 3-carene, a bio-fuel, have been carried out behind the reflected shock wave in a single pulse shock tube for temperature ranging from 920 K to 1220 K. The observed products in thermal decomposition of 3-carene are acetylene, allene, butadiene, isoprene, cyclopentadiene, hexatriene, benzene, toluene and p-xylene. The overall rate constant for 3-carene decomposition was found to be k / s-1 = 10(9.95 ± 0.54) exp (- 40.88 ± 2.71 kcal mol-1/RT). Ab-initio theoretical calculations were carried out to find the minimum energy pathway that could explain the formation of the observed products in the thermal decomposition experiments. These calculations were carried out at B3LYP/6-311 + G(d,p) and G3 level of theories. A kinetic mechanism explaining the observed products in the thermal decomposition experiments has been derived. It is concluded that the linear hydrocarbons are the primary products in the pyrolysis of 3-carene.
- Sharath,Chakravarty,Reddy,Barhai,Arunan
-
-
Read Online
- A facile strategy to prepare shaped ZSM-5 catalysts with enhanced para-xylene selectivity and stability for toluene methylation: The effect of in situ modification by attapulgite
-
A general strategy for preparing shaped toluene methylation catalysts with enhanced para-selectivity and stability is developed by extruding ZSM-5 zeolite with attapulgite as a binder. The novel attapulgite/ZSM-5 extrudate exhibited significantly higher para-selectivity and stability in comparison to the conventional alumina-bound ZSM-5 extrudate. The catalyst samples have been characterized by in situ X-ray diffraction, scanning electron microscope (SEM), NH3 temperature programmed desorption (TPD), thermogravimetric analysis (TGA) as well as n-hexane/cyclohexane physical adsorption. The enhanced catalytic performance of attapulgite/ZSM-5 extrudate is correlated with the in-situ modification of acid sites in the catalyst by mobile alkaline species, which is introduced via extrusion with attapulgite. Moreover, a higher para-selectivity was obtained over attapulgite-bound modified ZSM-5 extrudate. Such facile and universal strategy of extruding ZSM-5 catalysts with attapulgite as binder could pave a way for preparation of shaped zeolite-base catalyst with enhanced catalytic performance.
- Wang, Yiren,Chang, Yang,Liu, Min,Zhang, Anfeng,Guo, Xinwen
-
-
Read Online
- Renewable p-Xylene from 2,5-Dimethylfuran and Ethylene Using Phosphorus-Containing Zeolite Catalysts
-
p-Xylene is a major commodity chemical used for the production of polyethylene terephthalate, a polymer with applications in polyester fibers, films, and bottles. The Diels–Alder cycloaddition of 2,5-dimethylfuran and ethylene and the subsequent dehydration of the cycloadduct intermediate is an attractive reaction pathway to produce renewable p-xylene from biomass feedstocks. However, the highest yields reported previously do not exceed 75 %. We report that P-containing zeolite Beta is an active, stable, and selective catalyst for this reaction with an unprecedented p-xylene yield of 97 %. It can catalyze the dehydration reaction selectively from the furan-ethylene cycloadduct to p-xylene without the production of alkylated and oligomerized products. This behavior is distinct from that of Al-containing zeolites and other solid phosphoric acid catalysts and establishes a commercially attractive process for renewable p-xylene production.
- Cho, Hong Je,Ren, Limin,Vattipalli, Vivek,Yeh, Yu-Hao,Gould, Nicholas,Xu, Bingjun,Gorte, Raymond J.,Lobo, Raul,Dauenhauer, Paul J.,Tsapatsis, Michael,Fan, Wei
-
-
Read Online
- Diels-Alder and dehydration reactions of furan derivatives with ethylene catalyzed by liquid Br?nsted acids and Lewis acids
-
The tandem Diels-Alder and dehydration reactions of furan derivatives with ethylene represent a promising approach for the production of renewable aromatics. Herein, a series of haloacetic acids and rare-earth metal triflates are employed as liquid Br?nsted and Lewis acid catalysts, respectively, in the Diels-Alder and dehydration reactions of 2,5-dimethylfuran with ethylene to get an insight of this type of acid-catalyzed reaction. With the carefully selected catalysts and solvent, a quasi-homogeneous reaction system can be formed, where accurate kinetic studies could be performed. Haloacetic acids exhibit considerable activity in the Diels-Alder and dehydration reactions with a similar apparent activity energy value of ～8.4 kcal/mol, and CF2ClCOOH with a proper Br?nsted acidity is optimized for the reaction. Rare-earth metal triflates also exhibit considerable activity in the Diels-Alder and dehydration reactions with a similar apparent activity energy value of ～13.0 kcal/mol, and Sc(OTf)3 with the highest Lewis acidity is optimized. On the basis of kinetic analysis results, the impacts of acidity on the performance of catalysts are discussed in detail and the reaction network is proposed. Besides, the substrate scope of furan derivatives for the Diels-Alder and dehydration reactions with ethylene is investigated using CF2ClCOOH and Sc(OTf)3 as catalysts for possible extensions of the reaction.
- Song, Song,Wu, Guangjun,Dai, Weili,Guan, Naijia,Li, Landong
-
-
Read Online
- Effect of extra-framework Al formed by successive steaming and acid leaching of zeolite MCM-22 on its structure and catalytic performance
-
Dealuminated MCM-22 samples have been prepared by a two-step dealumination procedure. Detailed assessment of the properties of the materials obtained at each one of the successive stages, i.e. steaming (at 500 °C, 700 °C and 800 °C) and acid reflux (HCl and oxalic), has been made by XRD, N 2 adsorption-desorption, m-xylene adsorption, 27Al MAS NMR and FT-IR of pyridine adsorption. It was found that steaming generates extra-framework aluminum (EFAl) species and the majority of them cannot be extracted by the consecutive acid leaching. These extra-lattice entities block the zeolite micropores which makes the remaining Broensted acid sites isolated and inefficient. It is shown that the presence of such species vastly affects the catalytic performance of zeolite MCM-22 in the reaction of m-xylene conversion. The consequences are reduced adsorption capacity and catalytic activity, modified reaction products distribution, enhanced p-xylene selectivity, as well as altered mode of coke formation and composition of the coke precursors.
- Mihályi,Kollár,Király,Karoly,Mavrodinova
-
-
Read Online
- From Biomass-Derived Furans to Aromatics with Ethanol over Zeolite
-
We report a novel catalytic conversion of biomass-derived furans and alcohols to aromatics over zeolite catalysts. Aromatics are formed via Diels–Alder cycloaddition with ethylene, which is produced in situ from ethanol dehydration. The use of liquid ethanol instead of gaseous ethylene, as the source of dienophile in this one-pot synthesis, makes the aromatics production much simpler and renewable, circumventing the use of ethylene at high pressure. More importantly, both our experiments and theoretical studies demonstrate that the use of ethanol instead of ethylene, results in significantly higher rates and higher selectivity to aromatics, due to lower activation barriers over the solid acid sites. Synchrotron-diffraction experiments and proton-affinity calculations clearly suggest that a preferred protonation of ethanol over the furan is a key step facilitating the Diels–Alder and dehydration reactions in the acid sites of the zeolite.
- Teixeira, Ivo F.,Lo, Benedict T. W.,Kostetskyy, Pavlo,Stamatakis, Michail,Ye, Lin,Tang, Chiu C.,Mpourmpakis, Giannis,Tsang, Shik Chi Edman
-
-
Read Online
- Interference by Phosphine Decomposition in Oxidative Additions of Aryl Halides to Methyl-, and Trimethylsilyl-tris(triphenylphosphine)Cobalt
-
The oxidative addition of aryl halides, ArX, to 3CoCH3 yield ArAr and ArCH3 when Ar= 4-CH3C6H4, but exclusively ArCH3 for 1- and 2-bromo-naphthalene and 4-bromobiphenyl.Decomposition of the phosphine ligand in 3CoCH3 interfers with these reactions to varying extents depending on the relative rates of the reactions; ArCl mostly gives PhPh with some ArPh and ArAr; ArI gives mostly ArAr; ArBr shows intermediate behaviour.Other cobalt compounds such as 3CoSi3, 3CoCH3, 3CoPh and 3CoCH3 and several other organic halides examined show a low activity in the oxidative addition.
- Michman, M.,Chocron, S.,Nussbaum, S.,Schumann, H.,Montachemi, R.,Kannert, G.
-
-
Read Online
- Reductive electrocatalytic dehalogenation of nitrobenzyl halides: Nitrophilic or halophilic attack?
-
Electrochemical reduction of Cp2TiCl2 in the presence of benzylic halides results in their catalytic dehalogenation to form toluene derivatives. Possible schemes for the process were proposed on the basis of the results of electrochemical studies and digital simulation data. The catalytic scheme including the halophilic attack of the TiIII complex to organic halide as a key step occurs for unsubstituted benzylic halides. In the case of nitro-substituted substrates, the reaction is strongly accelerated. In this case, an electron transfer from the reduced form of the catalyst to the NO2 group of organic halide is possibly accompanied by the intramolecular charge transfer to the C-Hal bond, thus facilitating its cleavage. Thus, the nitro group in the starting benzylic halide acts as a "redox antenna," transferring an electron to the C-Hal bond. The proposed scheme is supported by semiempirical calculations of the geometry of molecular complexes with the Ti-Hal or Ti-NO2 coordination.
- Magdesieva,Nikitin,Dem'yanov,Graczyk,Vallat,Vorotyntsev,Butin
-
-
Read Online
- A Simple and Mild Approach for the Synthesis of p-Xylene from Bio-Based 2,5-Dimethyfuran by Using Metal Triflates
-
The production of aromatic platform chemicals from biomass-derived feedstocks is of considerable importance in biomass conversion. However, the development of effective routes with simple steps and under mild conditions is still challenging. In this work, we report an original route for the direct synthesis of p-xylene from 2,5-dimethylfuran and acrylic acid catalyzed by scandium(III) triflate (Sc(OTf)3) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Emim]NTf2) under mild conditions. An overall 63 % selectivity towards p-xylene and 78 % selectivity towards aromatics were obtained at 90 % conversion of 2,5-dimethylfuran by enhancing the dehydration and introducing an extra one-pot decarboxylation step. Furthermore, various dienes and dienophiles were employed as reactants to extend the substrate scope. The aromatic compounds were obtained in moderate yields, which proved the potential of the method to be a generic approach for the conversion of bio-based furanics into renewable aromatics.
- Ni, Lingli,Xin, Jiayu,Dong, Huixian,Lu, Xingmei,Liu, Xiaomin,Zhang, Suojiang
-
-
Read Online
- P -Xylene from 2,5-dimethylfuran and acrylic acid using zeolite in a continuous flow system
-
The continuous flow synthesis of p-xylene (pXL) via Diels-Alder cycloaddition of lignocellulosic biomass-derivable 2,5-dimethylfuran (DMF) and acrylic acid (AA) was performed over different type of zeolites, i.e. Beta, ZSM-5 and Y. Among the tested zeolites, Beta zeolite showed an optimum catalytic performance in pXL synthesis from DMF and AA. In this context, Beta zeolite with a Si/Al molar ratio of 150 which is abbreviated as Beta(150), resulted in complete DMF conversion with a pXL yield of 83% and by-product 2,5-dimethylbenzoic acid (DMBA) with a yield of 17%, at 473 K in 10.1 min residence time (τ), with excess AA (0.7 M). This high catalytic activity is attributed to the high specific surface area of 1180 m2 g-1 with a three-dimensional porous architecture with a pore diameter of 6.6 × 6.7 ? and an acid site density above 40 μmol g-1. The utilized Beta(150) showed a very stable performance up to 10 h time on stream with minor deactivation after 8 h of TOS, while the pXL yield remained above 70%. The original catalytic performance of Beta(150) in the conversion of DMF to pXL was restored by applying a regeneration step for the spent catalyst, which is simple in continuous flow reactors. Finally, this sustainable continuous flow process enables an efficient and selective pXL production from DMF and AA as a dienophile at lower reaction temperature (473 K) and shorter residence time (τ = 10.1 min) in comparison to a batch fashion. This journal is
- Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco,Mendoza Mesa, Jose Alirio,Shekova, Irina
-
-
Read Online
- The miracle role of lattice imperfections in benzene alkylation with methanol over mordenite
-
Mordenite (MOR) has demonstrated potential as a catalyst for alkylation due to high variability, intrinsic porosity, and outstanding stability. However, the contact probability of benzene and methanol has been limited by typical layered structures of MOR and there is no connection between layers. Here, we report the preparedness of H-MOR via a sequential post-treatment method based on a commercial MOR. H-MOR sample had appeared lattice imperfections inferred from characterization means. The samples were tested with benezene methylation reaction. Results show that the high conversion of benzene and the high selectivity of toluene were obtained from the miracle role of lattice imperfections in the H-MOR sample. Sequentially, based on the study of all catalyst structure and physical properties, a plausible reaction mechanism for the selectivity of the desired toluene was proposed.
- Yun, Hongfei,Meng, Jiale,Li, Guixian,Dong, Peng
-
-
Read Online
- Diels–Alder Conversion of Acrylic Acid and 2,5-Dimethylfuran to para-Xylene Over Heterogeneous Bi-BTC Metal-Organic Framework Catalysts Under Mild Conditions
-
The heterogeneous metal-organic framework Bi-BTC successfully catalyzed the synthesis of para-xylene from bio-based 2,5-dimethylfuran and acrylic acid in a promising yield (92 %), under relatively mild conditions (160 °C, 10 bar), and with a low reaction-energy barrier (47.3 kJ mol?1). The proposed reaction strategy also demonstrates a remarkable versatility for furan derivatives such as furan and 2-methylfuran.
- Yeh, Jyun-Yi,Chen, Season S.,Li, Shih-Cheng,Chen, Celine H.,Shishido, Tetsuya,Tsang, Daniel C. W.,Yamauchi, Yusuke,Li, Yi-Pei,Wu, Kevin C.-W.
-
-
Read Online
- Preparation of active Cs2HPW12O40 catalyst with the 'core-shell' secondary structure by a self-organizing process
-
By mixing and ageing of the powdered H3PW12O 40 acid and the Cs3PW12O40 salt, at the molar ratio of 1:2, the Cs2HPW12O40 salt with a unique 'core-shell' secondary structure is being formed. The self-organizing process proceeds in a solid state at ambient temperature and its rate depends on the humidity of air atmosphere. The formation of new secondary structure of the Cs2HPW12O40 salt was proved by number of techniques (XRD, DRIFT, DSC/TG and N2-sorption). Its properties were compared with those of the Cs2HPW12O40 salt prepared by the standard method, with the 'solid solution' secondary structure. The characterization techniques evidenced the substantial differences between various structures of the Cs2HPW12O40 salt. The microcalorimetric method showed that the process of ammonia sorption on the Cs2HPW12O40 salt with the new structure is quite similar to that on the K2HPW12O40 salt with well-known 'core-shell' structure. The catalytic activity of the Cs 2HPW12O40 samples with different secondary structure was compared in the dehydration of ethanol and in the transformation of m-xylene. It turn out that the Cs2HPW12O40 salt with the 'core-shell' structure exhibited significantly higher catalytic activity than the same salt with the 'solid solution' structure and was also more active than the Cs2.5H0.5PW12O 40 salt. It can be suggested that in the 'core-shell' structure of the Cs2HPW12O40 salt the protons are easily accessible for the reactants.
- Matachowski,Drelinkiewicz,Mucha,Kry?ciak-Czerwenka,Rachwalik
-
-
Read Online
- The One-electron Oxidation of 1,4-Dimethylcyclohexa-1,3-diene
-
1,4-Dimethylcyclohexa-1,3-diene reacts with (4-BrC6H4)3N(.+)SbCl6(-) by a mechanism involving both proton and electron hole catalysis to give the product of the cyclo-addition between the parent diene and 2,5-dimethylcyclohexa-1,3-diene acting as the dienophile; the persistent e.s.r. spectrum of the adduct can be observed.
- Davies, Alwyn G.,Hay-Montherwell, Robyn S.,Evans, Jeffrey C.,Rowlands, Christopher C.
-
-
Read Online
- Preparation and characterization of mesoporous Cs2HPW 12O40 salt, active in transformation of m-xylene
-
The samples of Cs2HPW12O40 salt were precipitated with CsCl, CsBr or CsI reagent as well as with commonly used Cs2CO3. The use of cesium halides resulted in the Cs 2HPW12O40 samples of mesoporous structure composed of relatively loosely aggregated primary particles. It was observed that the type of halogen ion influenced textural properties of the Cs 2HPW12O40 samples. As the atomic size of halogen ion increased (from Cl to I), the specific surface area and microporosity decreased. The so-obtained samples exhibited textural and morphological features similar to those of Cs2.5H 0.5PW12O40 salt. In the transformation of m-xylene, the pore-size sensitive reaction, the catalytic activity of the Cs2HPW12O40 samples prepared with CsBr and CsI reagents was about two-fold higher than that of Cs2.5H 0.5PW12O40 salt. All these samples exhibited similar strength of acid sites. Therefore, high catalytic activity of the samples prepared with CsBr and CsI could be ascribed to their open pore structure, which allowed the accessibility of almost all active sites for m-xylene molecules.
- Matachowski,Drelinkiewicz,Rachwalik,Zimowska,Mucha,Ruggiero-Miko?ajczyk
-
-
Read Online
- Selective conversion of methanol to p-xylene on modified high-silica zeolites
-
A procedure was proposed for preparation of p-xylene from a nonhydrocarbon material, methanol, in the presence of a modified ultrasil. It was shown that ultrasils modified by multiple-charge cations actively catalyze synthesis of xylenes from methanol at atmospheric pressure, and their properties can be controlled by varying the nature, charge, and size, as well as the procedure of introduction of the modifier cation. Modification of H-ultrasil with gallium led to enhanced para-selectivity (70%) of the catalysts, which was attributed to an increase in the ratio of the Lewis to Bronsted acid sites and to a decrease in the effective channel diameters of the zeolite.
- Mamedov,Gendzhalieva,Akhmedova
-
-
Read Online
- Lewis acid zeolites for tandem Diels-Alder cycloaddition and dehydration of biomass-derived dimethylfuran and ethylene to renewable p-xylene
-
Lewis acid zeolites including Zr-, Sn-, and Ti-BEA were examined for tandem [4 + 2] Diels-Alder cycloaddition of 2,5-dimethylfuran (DMF) and ethylene to oxanorbornene with subsequent dehydration to produce biorenewable p-xylene. Zr-BEA (Si/Zr = 168) exhibited superior performance with improved recalcitrance to deactivation, which was attributed to its low activity for the hydrolysis of DMF to 2,5-hexanedione and subsequent condensation. Zr-BEA also achieved the highest selectivity to p-xylene of 90% at 99% conversion of DMF. For low catalyst loading within a three-phase reactor, the reaction rate to form p-xylene was linearly proportional to the number of Lewis acid sites, while high catalyst loading exhibited zero order dependence on Lewis acid sites. A maximum achievable reaction rate was shown to be consistent with a transition in rate-limiting reactions from dehydration of oxanorbornene, the Diels-Alder product, to the Diels-Alder cycloaddition of DMF and ethylene.
- Chang, Chun-Chih,Je Cho, Hong,Yu, Jingye,Gorte, Ray J.,Gulbinski, Jason,Dauenhauer, Paul,Fan, Wei
-
-
Read Online
- Ultra-selective cycloaddition of dimethylfuran for renewable p-xylene with H-BEA
-
p-Xylene, the precursor for PET bottles, was synthesized at 90% yield by [4 + 2] cycloaddition of biomass-derived ethylene and dimethylfuran followed by subsequent dehydration with Beta zeolite.
- Chang, Chun-Chih,Green, Sara K.,Williams, C. Luke,Dauenhauer, Paul J.,Fan, Wei
-
-
Read Online
- Atmospheric pressure microwave assisted heterogeneous catalytic reactions
-
The purpose of the study was to investigate microwave selective heating phenomena and their impact on heterogeneous chemical reactions. We also present a tool which will help microwave chemists to answer to such questions as "My reaction yields 90% after 7 days at reflux; is it possible to obtain the same yield after a few minutes under microwaves?" and to have an approximation of their reactions when conducted under microwaves with different heterogeneous procedures. This model predicting reaction kinetics and yields under microwave heating is based on the Arrhenius equation, in agreement with experimental data and procedures.
- Chemat-Djenni, Zoubida,Hamada, Boudjema,Chemat, Farid
-
-
Read Online
- Organic structure directing agent-free and seed-induced synthesis of enriched intracrystal mesoporous ZSM-5 zeolite for shape-selective reaction
-
Sowing the seeds: A sub-micron single-crystal-like ZSM-5 catalyst with enriched intracrystal mesopores is synthesized through a facile organic structure-directing agent-free and seed-induced route. The special crystal structure leads to significantly improved catalytic activity, well-preserved shape selectivity, and slow deactivation in the isomerization of o-xylene to p-xylene.
- Zhang, Hongbin,Song, Kunshan,Wang, Lei,Zhang, Hongxia,Zhang, Yahong,Tang, Yi
-
-
Read Online
- Excellent Performances of Dealuminated H-Beta Zeolites from Organotemplate-Free Synthesis in Conversion of Biomass-derived 2,5-Dimethylfuran to Renewable p-Xylene
-
Direct synthesis of renewable p-xylene (PX) by cycloaddition of biomass-derived 2,5-dimethylfuran (2,5-DMF) and ethylene was achieved over Al-rich H-beta zeolites synthesized by an organotemplate-free approach and their dealuminated counterparts with different Si/Al ratios. Among them, H-beta zeolite with an Si/Al ratio of 22, obtained from an Al-rich parent by dealumination, was found to be an excellent catalyst for the synthesis of PX. A PX yield of 97 % and 2,5-DMF conversion of 99 % were obtained under optimized conditions. These results are even better than those of a commercial H-beta zeolite prepared using a organotemplate synthesis with a similar Si/Al ratio of 19. The excellent performance of the H-beta zeolite with Si/Al ratio of 22 is closely related to its acidity and porous structure. A moderate Br?nsted/Lewis acid ratio can improve the conversion of 2,5-DMF to as high as 99 %. Furthermore, dealuminated H-beta zeolite has a secondary pore system that facilitates product diffusion, which increases the selectivity to PX. In addition, this catalyst shows better regeneration. After five successive regeneration cycles, the yield of PX was still as high as 85 % without obvious dealumination. This work provides a deeper understanding of the more general Diels–Alder cycloaddition of furan-based feedstocks and olefins and significantly improves the potential for the synthesis of chemicals from lignocellulosic biomass.
- Zhao, Rongrong,Zhao, Zhenchao,Li, Shikun,Parvulescu, Andrei-Nicolae,Müller, Ulrich,Zhang, Weiping
-
-
Read Online
- Absorption Spectra and Photochemical Rearrangements of Xylene and Methylcycloheptatriene Cations in Solid Argon
-
Matrix photoionization experiments have been performed for several p-dialkylbenzenes and alkylcycloheptatrienes.Broad absorptions at 23500 and 34700 cm-1 following UV matrix two-photon ionization of p-xylene are assigned to the parent cation, in agreement with photodissociation spectra of gaseous cation.A broad absorption at 20240 cm-1 following vacuum-UV matrix photoionization of 7-methylcycloheptatriene is assigned to the parent cation, in agreement with the difference between photoelectron bands.Mercury arc photolysis has been used to activate the extensive rearrangements of the p-xylene and 7-methylcycloheptatriene cations, which finally rearrange to a common conjugated triene cation identified as a substituted methylenecyclohexadiene cation.
- Kelsall, Benuel J.,Andrews, Lester,McGarvey, Glenn J.
-
-
Read Online
- Regeneration of Pentasil Zeolite Catalysts using Ozone and Oxygen
-
A novel procedure for the removal of carbonaceous deposits from zeolites using ozone-enriched oxygen is described.Pentasil zeolites (SiO2/Al2O3 mole ratios 35, 70) were studied and deactivated using methanol conversion to hydrocarbons and o-xylene isomerisation.Low temperature ozone reactivation was found to restore the catalyst activity for these reactions and hence can be considered as an alternative procedure to high temperature oxygen reactivation currently utilised industrially.Ozone reactivation was found to increase slightly the catalyst lifetime and also to reduce the initial methane yield when compared with oxygen reactivation.
- Copperthwaite, Richard G.,Hutchings, Graham J.,Johnston, Peter,Orchard, S. Walter
-
-
Read Online
- Kinetic Study of Carbonylation of α-Bromo-p-xylene with Iron Pentacarbonyl by Phase-Transfer Catalysis
-
The reaction kinetics of the carbonylation of α-bromo-p-xylene (BrCH2C6H4CH3, BX) with iron pentacarbonyl (Fe(CO)5) by phase-transfer catalysis was studied in an organic solvent/alkaline solution. The concentration of tetra-n-butylammonium bromide ((n-C4H9)4NBr, TBAB), NaOH, NaBr, aqueous volume and temperature were evaluated to achieve the optimum reaction condition. The reaction behavior was discussed by the apparent reaction-rate constants for BX and bis(p-methylbenzyl) ketone ((p-CH3C6H4CH2)2CO, BMBK), respectively, and the relationship of consumption of BX and Fe(CO)5. The product distributions of BX with Fe(CO)5 on various reactions conditions were measured. The activation energies was obtained at TBAB = 1.24 and 0 mmol as Well.
- Wu, Ho-Shing,Tan, Wen-Han
-
-
Read Online
- Direct observation and structural characterization of the encounter complex in bimolecular electron transfers with photoactivated acceptors
-
The encounter complex between photoexcited quirtones Q* and various aromatic donors (ArH) is observed directly by time-resolved ps spectroscopy immediately before it undergoes electron transfer to the ion-radical pair [Q(°-) ArH(°+)]. The encounter complex (EC) is spectrally characterized by distinctive (near IR) absorption bands, and its temporal evolution is established by quantitative kinetics analysis. The structural characterization of the 1:1 encounter complex [Q*, ArH] identifies the cofacial juxtaposition of the donor and acceptor moieties for optimal overlap of their π-orbitals. Further comparisons of the (excited-state) encounter complex with the corresponding (ground-state) EDA complex of aromatic donors and quinones establish its charge-transfer character, which directly relates to electron transfer within the encounter complex. The mechanistic significance of the encounter complex to bimolecular electron transfer is discussed (Scheme 1).
- Rathore,Hubig,Kochi
-
-
Read Online
- Synthesis of HZSM-5@silicalite-1 core-shell composite and its catalytic application in the generation of p-xylene by methylation of toluene with methyl bromide
-
A core-shell HZSM-5@silicalite-1 composite was synthesized by overgrowing silicalite-1 on the external surface of HZSM-5, and was characterized by XRD, SEM, TEM, NH3-TPD, 1,3,5-triisopropylbenzene (TIPB) cracking and N2 adsorption-desorption techniques. When used as a catalyst for the formation of p-xylene through toluene methylation with methyl bromide, the HZSM-5@silicalite-1 composite exhibits para-selectivity of up to 76% with no evidence of deactivation in an on stream period of 3 h. The excellent catalytic performance is attributed to the inactive silicalite-1 shell that extends the diffusion path length of xylenes while having the acid sites on the external surface of HZSM-5 fully covered. the Partner Organisations 2014.
- Deng, Yi-Qiang,Zhou, Wei-Fang,Lv, Hao-Ming,Zhang, Ying-Ying,Au, Chak-Tong,Yin, Shuang-Feng
-
-
Read Online
- Recovery of Arenes from Polyethylene Terephthalate (PET) over a Co/TiO2 Catalyst
-
Upcycling of spent plastics has become a more emergent topic than ever before due to the rapid generation of plastic waste associated with the change of lifestyles of the human society. Polyethylene terephthalate (PET) is a major aromatic plastic and herein, the conversion of PET back into arenes was demonstrated in a one-pot reaction combining depolymerization and hydrodeoxygenation (HDO) over a Co/TiO2 catalyst. The effectiveness of the Co/TiO2 catalyst in HDO and the underlining reaction pathway were established using the PET monomer terephthalic acid (TPA) as the substrate. Quantitative TPA conversion together with 75.2 mol% xylene and toluene selectivity under 30 bar initial H2 pressure at 340 °C was achieved after 4 h reaction. More encouragingly, the catalyst induced both depolymerization and HDO reaction via C?O bond cleavage when PET was used as a substrate. 78.9 mol% arenes (toluene and xylene) was obtained under optimized conditions.
- Hongkailers, Surachet,Jing, Yaxuan,Wang, Yanqin,Hinchiranan, Napida,Yan, Ning
-
-
Read Online
- Route to Renewable PET: Reaction Pathways and Energetics of Diels-Alder and Dehydrative Aromatization Reactions between Ethylene and Biomass-Derived Furans Catalyzed by Lewis Acid Molecular Sieves
-
Silica molecular sieves that have the zeolite beta topology and contain framework Lewis acid centers (e.g., Zr-β, Sn-β) are useful catalysts in the Diels-Alder and dehydrative aromatization reactions between ethylene and various renewable furans for the production of biobased terephthalic acid precursors. Here, the main side products in the synthesis of methyl 4-(methoxymethyl)benzene carboxylate that are obtained by reacting ethylene with methyl 5-(methoxymethyl)-furan-2-carboxylate are identified, and an overall reaction pathway is proposed. Madon-Boudart experiments using Zr-β samples of varying Si/Zr ratios clearly indicate that there are no transport limitations to the rate of reaction for the synthesis of p-xylene from 2,5-dimethylfuran and ethylene and strongly suggest no mass transport limitations in the synthesis of methyl p-toluate from methyl 5-methyl-2-furoate and ethylene. Measured apparent activation energies for these reaction-limited systems are small (13C kinetic isotope effects (KIE) in the synthesis of MMBC and MPT measured by gas chromatography/isotope-ratio mass spectrometry in reactant-depletion experiments support the Madon-Boudart result that these systems are not transport-limited and the KIE values agree with those previously reported for Diels-Alder cycloadditions.
- Pacheco, Joshua J.,Labinger, Jay A.,Sessions, Alex L.,Davis, Mark E.
-
-
Read Online
- Modification of H-Mordenite by a Vapour-phase Deposition Method
-
Depositing Si(OMe)4 from the vapour phase onto H-mordenite reduces the size of pore exits in the zeolite but leaves the acid sites unaltered.
- Niwa, Miki,Itoh, Hirofumi,Kato, Satoshi,Hattori, Tadashi,Murakami, Yuichi
-
-
Read Online
- Reductive Depolymerization of Plastic Waste Catalyzed by Zn(OAc)2 ? 2H2O
-
Plastic pollution is one of the biggest problems all over the world. Beyond change/awareness of consumer behavior, there is an urgent need to search for efficient, economical and environmentally friendly catalysts for the valorization of plastic waste to value-added compounds. This work describes the reductive depolymerization of several types of plastic waste into value-added compounds, including 1,6-hexanediol, 1,2-propanediol, p-xylene and tetrahydrofuran, in good yields using the eco-friendly, air-stable, commercially available and very cheap catalyst Zn(OAc)2 ? 2H2O. This is the first example of the reductive depolymerization of polyester waste catalyzed by a zinc catalyst. Moreover, the catalytic system silane/Zn(OAc)2 ? 2H2O was successfully applied to the reduction of polycaprolactone (PCL) on the gram scale with good yield and also to the selective reductive depolymerization of plastic mixtures. Finally, this work demonstrated that the catalyst Zn(OAc)2 ? 2H2O can be used in at least 7 cycles with good yields.
- Fernandes, Ana C.
-
-
Read Online
- Quantification of Bronsted acid sites of grafted amorphous silica-alumina compounds and their turnover frequency in m-xylene isomerization
-
The number and types of acid sites and the catalytic activity of amorphous silica-alumina, obtained by grafting silicon species to the surface of γ-alumina, varies with the synthesis conditions and the amount of grafted silicon. IR spectroscopy of the OH region proves that deposition occurs selectively, first on the (1 0 0) and then on the (1 1 0) facets. Grafting onto the (1 0 0) surface lowers the number of active sites in ethanol dehydration. Grafting onto the (1 1 0) surface yields Bronsted acid sites that are active in the dehydration of ethanol and that catalyze the isomerization of m-xylene. Strong Lewis acid sites, or "defect sites", as detected by CO adsorption, also appear, although they are absent on the parent alumina. The stoichiometric dehydration of ethanol on Bronsted sites, monitored by using thermogravimetric analysis, enables the calculation of the turnover frequency of these sites in m-xylene isomerization (1.410-3 s -1 site-1 at 350 °C, atmospheric pressure, 0.6 cm 3 h-1 of m-xylene, and 0.5 g of catalyst). This number is 22 times lower than on a USY zeolite without extraframework aluminum. Multifaceted γ-alumina: Under mild conditions, tetraethyl orthosilicate (TEOS) is first deposited on the (1 0 0) surface of γ-alumina, and then on the (1 1 0) surface. The latter step enables the formation of Bronsted acid sites upon calcination, which are less active than those present in an H-USY zeolite. Copyright
- Caillot, Maxime,Chaumonnot, Alexandra,Digne, Mathieu,Bokhoven, Jeroen A. Van
-
-
Read Online
- STUDY OF THE RADICAL-CATIONS OF TRIETHYLAMINE AND BENZENE DERIVATIVES BY THE OPTICAL DETECTION OF THE EPR SPECTRA OF RADICAL-ION PAIRS
-
The ODEPR method has been used to obtain the spectra of the radical-cations of hexamethylbenzene, durene, para-xylene, and triethylamine in nonpolar liquid solutions at different temperatures, including temperatures close to room temperature.The values of the HFS constants of the radical-cations whose spectra have been recorded for the first time (para-xylene and triethylamine) have been found to be close to the theoretically calculated values.
- Grigoryants, V. M.,Anisimov, O. A.,Molin, Yu. N.
-
-
Read Online
- Preparation of an MCM-22/Hydrotalcite Framework Composite and Its Catalytic Application
-
A composite material (MAMCM), possessing both a layered cationic MgAl-hydrotalcite (MA-HT) and an anionic MCM-22 framework, was prepared by a simple coprecipitation method. The resulting composite material has features of both MCM-22 and the HT layered framework, as shown by powder XRD, FTIR, 29Si and 27Al-MAS NMR spectroscopy, and SEM studies. Electron microscopy revealed that the layer sheets are arranged in a spherical morphology. The composite material was utilized for the vapor-phase alkylation of toluene. The MAMCM material showed better toluene conversion than MCM-22 and MA-HT materials.
- Baskaran, Thangaraj,Christopher, Jayaraj,Mariyaselvakumar, Mariyamuthu,Sakthivel, Ayyamperumal
-
-
Read Online
- Self-catalysis in arene exchange reactions of (arene)tricarbonylchromium complexes
-
The replacement of p-xylene from its tricarbonylchromium complex by benzene is catalyzed by (hexamethylbenzene)tricarbonylchromium without the replacement of hexamethylbenzene. This and other observations suggest that the bound carbonyl group acts as a nucleophilic catalyst in arene exchange.
- Traylor,Stewart, Kevin
-
-
Read Online
- ORBITAL-CONTROLLED REACTIONS CATALYSED BY ZEOLITES: ELECTROPHILIC ALKYLATION OF AROMATICS
-
The role of orbital control in product selectrivity during electrophilic alkylation catalysed by zeolites was studied both theoretically and experimentally.In order to discuss this, the alkylation of toluene and m-xylene by methanol was carried out on a series of large-pore zeolites (HY).The changes in the para to ortho ratio observed on changing the framework Si/Al ratio of the zeolites were related to ab initio molecular orbital calculations of the LUMO energy of structurally alike model clusters but containing different tetrahedral cations around the active site.The observed correlation is discussed in terms of the HSAB principle by taking into account the influence of the catalyst composition on the reactivity of the electrophilic reagent.
- Corma, A.,Zicovich-Wilson, C.,Viruela, P.
-
-
Read Online
- Three-dimensional 10-ring zeolites: The activities in toluene alkylation and disproportionation
-
Three-dimensional 10-ring zeolites TUN, IMF, -SVR, MFI and MEL were investigated as for their acid properties, adsorption of 2,2-dimethylbutane and in toluene disproportionation and its alkylation with isopropyl alcohol. The results were compared against zeolite?SFV, the structure of which consists mainly of MEL zeolite with some additional 12-ring channel system. With exception of -SVR synthesized with high Si/Al ratio, all other zeolites provided Si/Al ratios in a narrow region. Novel zeolites TUN, IMF, and -SVR exhibited higher conversions than MFI and MEL in toluene alkylation. TUN and IMF were substantially more active in toluene disproportionation indicating less diffusion restrictions of channel structure on the disproportionation reaction.?SFV showed a similar catalytic behavior to MEL with much lower selectivity to p-xylene and p-cymene. This could indicate that both toluene disproportionation and alkylation proceed in reaction space of?SFV being similar to those of MFI and MEL.?SFV and TUN exhibited much faster adsorption of 2,2-dimethylbutane than MFI, MEL, IMF, and -SVR. It was concluded that the presence of some larger transport pores in?SFV than in other zeolites is responsible for fast adsorption of 2,2-dimethylbutane and transport of products resulting in a low selectivity to p-xylene and p-cymene.
- Kub?, Martin,?ilková, Nadě?da,Zones, Stacey I.,Chen, Cong-Yan,Al-Khattaf, Sulaiman,?ejka, Ji?í
-
-
Read Online
- Transformation of aromatic hydrocarbons over isomorphously substituted UTL: Comparison with large and medium pore zeolites
-
Isomorphously substituted UTL zeolite with heteroatoms Al, Ga and Fe was synthesized, characterized by X-ray powder diffraction, scanning electron images, nitrogen adsorption isotherms and pyridine adsorption followed by FTIR spectroscopy and tested in disproportionation of toluene, toluene alkylation with isopropyl alcohol and trimethylbenzene disproportionation/isomerization. The catalytic properties of UTL zeolites were compared with those of BEA and MFI zeolites and the observed differences are discussed. Isomorphously substituted (Al, Ga, Fe) UTL zeolites show in most cases lower conversions for the reactions studied but higher selectivities to more valuable products. For toluene disproportionation reaction UTL zeolites shown higher selectivity to xylenes compared with BEA and MFI. In toluene alkylation with isopropyl alcohol no n-propyltoluenes are formed(Ga)UTL or (Fe)UTL while some traces of this undesired product were observed(Al)UTL. (Al)UTL shows high selectivity to cymenes and iso-/n-propyltoluene ratio orders of magnitude higher than for MFI. The initial selectivity to xylenes in trimethylbenzene disproportionation/ isomerization decreases in the order (Ga)UTL > (Al)UTL ≈ BEA > MFI and correlates with increasing of acid centres strength, showing that isomorphously substituted extra-large pore zeolites can be enough active and more selective catalysts in some aromatic hydrocarbon transformation reaction.
- ?ilková, Nadě?da,Shamzhy, Mariya,Shvets, Oleksiy,?ejka, Ji?í
-
-
Read Online
- Effect of silica content on production of p-Xylene from dimethylfuran/ethylene over mesoporous SiO2-Al2O3 catalysts
-
Mesoporous SiO2-Al2O3 (SA) catalysts with different SiO2 contents were prepared, for the selective production of p-xylene from dimethylfuran/ethylene through the combination of cycloaddition and dehydrative aromatization reactions, by a co-precipitation method. For comparison, commercial SiO2-Al2O3 and ZSM-5 zeolites (Si/Al2 = 30, Si/Al2 = 80) were also employed as catalysts in the same reaction. The pore size of the catalysts played an important role in determining the catalytic performance in the production of p-xylene. Among the catalysts tested, the order of the yield and production rate of p-xylene was as follows: mesoporous SA > commercial SiO2-Al2O3 > commercial ZSM-5. In the mesoporous SA catalysts in particular, p-xylene yields showed a volcano-shaped trend with respect to the catalyst's SiO2 content. The SA-60 catalyst, with SiO2 = 52.3, showed the highest yield (75%) and production rate (57.7 mmol/g-cat · h) because of a catalyst structure with moderate pore size, which prevented side reactions.
- Lee, Jin Sil,Kim, Sang Yun,Kim, Tae-Wan,Jeong, Soon-Young,Kim, Chul-Ung,Lee, Kwan-Young
-
-
Read Online
- Rational Design of Zinc/Zeolite Catalyst: Selective Formation of p-Xylene from Methanol to Aromatics Reaction
-
The production of p-xylene from the methanol to aromatics (MTA) reaction is challenging. The catalytic stability, which is inversely proportional to the particle size of the zeolite, is not always compatible with p-xylene selectivity, which is inversely proportional to the external acid sites. In this study, based on a nano-sized zeolite, we designed hollow triple-shelled Zn/MFI single crystals using the ultra-dilute liquid-phase growth technique. The obtained composites possessed one ZSM-5 layer (≈30 nm) in the middle and two silicalite-1 layers (≈20 nm) epitaxially grown on two sides of ZSM-5, which exhibited a considerably long lifetime (100 % methanol conversion >40 h) as well as an enhanced shape selectivity of p-xylene (>35 %) with a p-xylene/xylene ratio of ≈90 %. Importantly, using this sandwich-like zeolite structure, we directly imaged the Zn species in the micropores of only the ZSM-5 layer and further determined the specific structure and anchor location of the Zn species.
- Chen, Biaohua,Chen, Congmei,Chen, Xiao,Hou, Yilin,Hu, Xiaomin,Li, Jing,Qian, Weizhong,Sun, Wenjing,Wang, Ning,Yang, Yifeng,Zhang, Lan
-
supporting information
(2022/02/16)
-
- One-Pass Conversion of Benzene and Syngas to Alkylbenzenes by Cu–ZnO–Al2O3 and ZSM-5 Relay
-
Alkylbenzenes have a wide range of uses and are the most demanded aromatic chemicals. The finite petroleum resources compels the development of production of alkylbenzenes by non-petroleum routes. One-pass selective conversion of benzene and syngas to alkylbenzenes is a promising alternative coal chemical engineering route, yet it still faces challenge to industrialized applications owing to low conversion of benzene and syngas. Here we presented a Cu–ZnO–Al2O3/ZSM-5 bifunctional catalyst which realizes one-pass conversion of benzene and syngas to alkylbenzenes with high efficiency. This bifunctional catalyst exhibited high benzene conversion (benzene conversion of 50.7%), CO conversion (CO conversion of 55.0%) and C7&C8 aromatics total yield (C7&C8 total yield of 45.0%). Characterizations and catalytic performance evaluations revealed that ZSM-5 with well-regulated acidity, as a vital part of this Cu–ZnO–Al2O3/ZSM-5 bifunctional catalyst, substantially contributed to its performance for the alkylbenzenes one-pass synthesis from benzene and syngas due to depress methanol-to-olefins (MTO) reaction. Furthermore, matching of the mass ratio of two active components in the dual-function catalyst and the temperature of methanol synthesis with benzene alkylation reactions can effectively depress the formation of unwanted by-products and guarantee the high performance of tandem reactions. Graphic Abstract: [Figure not available: see fulltext.]
- Dong, Jinxiang,Ge, Hui,Han, Tengfei,Li, Xuekuan,Liu, Jianchao,Xu, Hong,Zhou, Ligong
-
-
- Comparison of Physicochemical Properties and Catalytic Activity in the m-Xylene Isomerization of Catalysts Based on ZSM-12 Zeolites Prepared at Hydrothermal Conditions and under the Action of Microwave Radiation
-
The properties of ZSM-12 zeolites prepared under hydrothermal conditions and microwave radiation influence were investigated. The prepared zeolites were characterized by various physicochemical methods of analysis, e.g., X-ray diffraction analysis, low-temperature nitrogen adsorption/desorption, scanning electron microscopy, solid-state 27Al and 29Si NMR spectroscopy, IR spectroscopy, temperature-programmed desorption of ammonia, IR spectroscopy of adsorbed pyridine, and X-ray fluorescence elemental analysis. The calcined zeolites were impregnated with 0.5 wt.% Pt, which performed the hydrogenation function in the reaction under study. The obtained materials were evaluated in the m-xylene isomerization reaction under the following conditions: Т = 300°С–440°С, WHSV = 1/hr, Р(Н2) = 10 atm. On the ZSM-12 MW catalyst, due to its high acidity and fine particles, which promoted high mass transfer, it is possible to increase the yields of m-xylene isomers, in particular p-xylene, to 36%–65%.
- Tsaplin,Ostroumova,Kulikov,Naranov,Egazar’yants,Karakhanov
-
p. 1292 - 1301
(2021/12/29)
-
- Evaluation of the Properties of ZSM-5 Type Zeolites Modified with CexMg1–xAl2O4 Nanopowders in the Toluene Disproportionation Reaction
-
Abstract: The effect of CexMg1–xAl2O4 spinel nanopowders on the textural, acidic, and catalytic properties displayed by HZSM-5 zeolite in the toluene disproportionation reaction was examined. Modification with CexMg1–xAl2O4 nanopowders caused a decrease in the concentration of strong protonic sites, formation of new stronger aprotonic sites, and a decrease in the pore volume of HZSM-5, thereby creating more steric hindrance to diffusion of o- and m-xylenes and enhancing para-selectivity of the catalyst. The possibility of achieving high p-xylene selectivity of 65.7–77.3% via toluene disproportionation over the optimal 5% Сe0.1Mg0.9Al2O4/HZSM-5 catalyst at toluene conversion of 20.3–29.7% was demonstrated. [Figure not available: see fulltext.]
- Akhmedov, E. I.,Akhmedova, N. F.,Ilyasli, T. M.,Kerimli, F. Sh.,Makmudova, N. I.,Mammadov, E. S.,Mammadov, S. E.
-
p. 895 - 900
(2021/08/13)
-
- Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions
-
Upgrading biomass-derived phenolic compounds provides a valuable approach for the production of higher-value-added fuels and chemicals. However, most established catalytic systems display low hydrodeoxygenation (HDO) activities even under harsh reaction conditions. Here, we found that Pd supported on –NH2-modified hierarchically porous carbon (Pd/HPC–NH2) with formic acid (FA) as hydrogen source exhibits unprecedented performance for the selective HDO of benzylic ketones from crude lignin-derived oxygenates. Designed experiments and theoretical calculations reveal that the H+/H? species generated from FA decomposition accelerates nucleophilic attack on carbonyl carbon in benzylic ketones and the formate species formed via the esterification of intermediate alcohol with FA expedites the cleavage of C–O bonds, achieving a TOF of 152.5 h?1 at 30°C for vanillin upgrading, 15 times higher than that in traditional HDO processes (～10 h?1, 100°C–300°C). This work provides an intriguing green route to produce transportation fuels or valuable chemicals from only biomass under mild conditions.
- Chen, Yuzhuo,Chen, Zhirong,Gong, Yutong,Mao, Shanjun,Ning, Honghui,Wang, Yong,Wang, Zhenzhen
-
p. 3069 - 3084
(2021/11/16)
-
- Iodine-catalyzed alcohol disproportionation method
-
The invention relates to the technical field of catalysis, in particular to an iodine-catalyzed alcohol disproportionation method which comprises the following steps: sequentially adding alcohol, iodine and a solvent into a high-temperature and high-pressure reaction kettle, introducing a certain amount of nitrogen, conducting reacting for a certain time, collecting an organic phase after the reaction is ended, and conducting fractionating to obtain corresponding alkane and aldehyde/ketone. Alcohol disproportionation is efficient and atom-economical conversion without any additional oxidizing agent and reducing agent, and hydrocarbon and aldehyde/ketone molecules which are easy to separate can be formed at the same time. Meanwhile, the method has wide functional group tolerance, various substrate samples including aryl alcohol derivatives, heterocyclic alcohol derivatives, allyl alcohol derivatives and dihydric alcohol are tested, and the result shows that most of the substrate samples show good or extremely good yield.
- -
-
Paragraph 0028-0029
(2021/06/13)
-
- Radical induced disproportionation of alcohols assisted by iodide under acidic conditions
-
The disproportionation of alcohols without an additional reductant and oxidant to simultaneously form alkanes and aldehydes/ketones represents an atom-economical transformation. However, only limited methodologies have been reported, and they suffer from a narrow substrate scope or harsh reaction conditions. Herein, we report that alcohol disproportionation can proceed with high efficiency catalyzed by iodide under acidic conditions. This method exhibits high functional group tolerance including aryl alcohol derivatives with both electron-withdrawing and electron-donating groups, furan ring alcohol derivatives, allyl alcohol derivatives, and dihydric alcohols. Under the optimized reaction conditions, a 49% yield of 5-methyl furfural and a 49% yield of 2,5-diformylfuran were obtained simultaneously from 5-hydroxymethylfurfural. An initial mechanistic study suggested that the hydrogen transfer during this redox disproportionation occurred through the inter-transformation of HI and I2. Radical intermediates were involved during this reaction.
- Huang, Yang,Jiang, Haiwei,Li, Teng,Peng, Yang,Rong, Nianxin,Shi, Hexian,Yang, Weiran
-
supporting information
p. 8108 - 8115
(2021/10/29)
-
- Method for preparing p-xylene by efficiently catalyzing conversion of 4-methyl-3-cyclohexenecarboxaldehyde through ferronickel bimetallic catalyst
-
The invention provides a method for preparing p-xylene by efficiently catalyzing conversion of 4-methyl-3-cyclohexenecarboxaldehyde through a ferronickel bimetallic catalyst. The catalyst is an alumina-loaded bimetallic catalyst, 4-methyl-3-cyclohexenecarboxaldehyde is subjected to dehydrogenation aromatization and hydrodeoxygenation reaction at 100-300 DEG C under the action of the ferronickel bimetallic catalyst, p-xylene is efficiently generated, the ferronickel bimetallic catalyst can be prepared by an impregnation method, the 4-methyl-3-cyclohexenecarboxaldehyde catalytic reaction is carried out in a fixed bed reactor. According to the method, n-hexane is taken as a solvent, and a 4-methyl-3-cyclohexene formaldehyde solution is pumped into a reaction tube by a high-pressure flow pump, or passes through a catalyst bed layer under the purging of carrier gas to obtain p-xylene. The reaction process is simple in procedure and high in yield, the yield of p-xylene can reach 93% or above, and the catalyst is easy to prepare, high in activity, low in price and easy to obtain.
- -
-
Paragraph 0028-0040; 0049-0052
(2021/05/22)
-
- Method for preparing methylbenzene by efficiently catalyzing conversion of 3-cyclohexenecarboxaldehyde through copper-based bimetallic catalyst
-
The invention provides a method for preparing methylbenzene by efficiently catalyzing conversion of 3-cyclohexenecarboxaldehyde through a copper-based bimetallic catalyst. According to the method, 1, 3-cyclohexenecarboxaldehyde is subjected to dehydroaromatization and hydrodeoxygenation reaction at 100-300 DEG C under the action of a supported copper-based bimetallic catalyst, and toluene is efficiently generated. The catalytic reaction of 3-cyclohexenecarboxaldehyde is carried out in a fixed bed reactor, n-octane is used as a solvent, and a 3-cyclohexenecarboxaldehyde solution is pumped into a reaction tube by a high-pressure flow pump or passes through a catalyst bed layer under the purging of hydrogen gas to obtain toluene. The reaction process is simple, the target product selectivity is high, the substrate can be obtained by taking 1, 3-butadiene and acrolein from biomass resources as raw materials through a one-step reaction, and a novel method for directly preparing aromatic chemicals from biomass is provided.
- -
-
Paragraph 0040-0044; 0046-0050
(2021/05/22)
-
- Separation of Anisole and Valuable Byproducts from Liquid Reaction Mixtures by Solvent Extraction and Multicomponent Distillation
-
Anisole (methoxybenzene) is a widely used organic intermediate that can be synthesized via vapor-phase alkylation of phenol by methanol in the presence of a commercial NaX zeolite as a catalyst (SiO2:Al2O3 ratio of 2.6:3). The indigenously synthesized anisole is then separated from the multicomponent liquid reaction mixture, consisting of o-cresol, p-cresol and p-xylen, along with unreacted methanol and phenol. The separated anisole has substantial demand for applications in the chemical, pharmaceutical, plastics and pesticides industries. Separation of individual components from the reaction mixture requires identification of techniques that could be scaled up. Distillation is one of the most dependable techniques for the separation of multicomponent liquid mixtures. The novelty of the present study is the synthesis and separation of anisole along with individual components of methanol, phenol and o-cresol from its reaction mixture using a single distillation column under atmospheric and vacuum conditions, respectively. Through this process, the purity of the resulting methanol, anisole and phenol were found to be 99.99, 99.80 and 98.29% by simple distillation, whereas 91.0% pure o-cresol was separated by vacuum distillation due to its high boiling point. The experimental results were used to calculate the material, individual component and energy balances, whereas the PRO/II process simulation was performed to scale-up the process. On the other hand, anisole recovery from a synthetic multicomponent liquid mixture was also successfully conducted using solvent extraction. The overall observations found the integration of solvent extraction with distillation to be an effective, economical and dependable solution for the isolation of anisole and other important by-products.
- Vani, Bukke,Pabba, Manideep,Kalyani, Swayampakula,Sridhar, Sundergopal
-
p. 160 - 177
(2021/01/29)
-
- Metal-Free Heterogeneous Semiconductor for Visible-Light Photocatalytic Decarboxylation of Carboxylic Acids
-
A suitable protocol for the photocatalytic decarboxylation of carboxylic acids was developed with metal-free ceramic boron carbon nitrides (BCN). With visible light irradiation, BCN oxidize carboxylic acids to give carbon-centered radicals, which were trapped by hydrogen atom donors or employed in the construction of the carbon-carbon bond. In this system, both (hetero)aromatic and aliphatic acids proceed the decarboxylation smoothly, and C-H, C-D, and C-C bonds are formed in moderate to high yields (35 examples, yield up to 93%). Control experiments support a radical process, and isotopic experiments show that methanol is employed as the hydrogen atom donor. Recycle tests and gram-scale reaction elucidate the practicability of the heterogeneous ceramic BCN photoredox system. It provides an alternative to homogeneous catalysts in the valuable carbon radical intermediates formation. Moreover, the metal-free system is also applicable to late-stage functionalization of anti-inflammatory drugs, such as naproxen and ibuprofen, which enrich the chemical toolbox.
- Shi, Jiale,Yuan, Tao,Zheng, Meifang,Wang, Xinchen
-
p. 3040 - 3047
(2021/03/09)
-
- Towards the Circular Economy: Converting Aromatic Plastic Waste Back to Arenes over a Ru/Nb2O5 Catalyst
-
The upgrading of plastic waste is one of the grand challenges for the 21st century owing to its disruptive impact on the environment. Here, we show the first example of the upgrading of various aromatic plastic wastes with C?O and/or C?C linkages to arenes (75–85 % yield) via catalytic hydrogenolysis over a Ru/Nb2O5 catalyst. This catalyst not only allows the selective conversion of single-component aromatic plastic, and more importantly, enables the simultaneous conversion of a mixture of aromatic plastic to arenes. The excellent performance is attributed to unique features including: (1) the small sized Ru clusters on Nb2O5, which prevent the adsorption of aromatic ring and its hydrogenation; (2) the strong oxygen affinity of NbOx species for C?O bond activation and Br?nsted acid sites for C?C bond activation. This study offers a catalytic path to integrate aromatic plastic waste back into the supply chain of plastic production under the context of circular economy.
- Jing, Yaxuan,Wang, Yanqin,Furukawa, Shinya,Xia, Jie,Sun, Chengyang,Hülsey, Max J.,Wang, Haifeng,Guo, Yong,Liu, Xiaohui,Yan, Ning
-
supporting information
p. 5527 - 5535
(2021/02/05)
-
- Effect of H2SiF6modification of IM-5 on catalytic performance in benzene alkylation with ethylene
-
Ethylbenzene (EB) is an important bulk chemical intermediate. The vapor-phase process is considered to be more efficient than the liquid-phase process when using dilute ethylene (e.g. FCC or DCC off-gas) as the feed due to its high ethylene space velocity. However, realizing a balance between reducing the xylene formation and enhancing the EB selectivity is still a challenge due to the poor performance of ZSM-5 at low reaction temperature. This study concerns an IM-5 zeolite (IMF topology) modified by H2SiF6, with 89% ethylbenzene selectivity, 98.6% total EB + DEB selectivity and only 540 ppm of xylene at 330 °C. IM-5 zeolites with different Si/Al2 ratios (40-170) were prepared by H2SiF6 modification and their catalytic performance in vapor phase alkylation of benzene with ethylene was investigated. There was an obvious decrease in the acid sites and acid strength of IM-5 in the H2SiF6 treatment process, which led to a slight decrease in ethylbenzene selectivity and a significant decline in xylene yield. Under the conditions of complete ethylene conversion, the selectivity to EB + DEB increased from 96.1% to 98.6% in the parent I-40 and modified IM-5. Compared with ZSM-5 that has a similar acidity, the slightly bigger channel opening makes IM-5 more conductive to the formation and diffusion of DEB while xylene may present adverse effects. The 120 hour-lifetime test showed that IM-5 (I-110) has superior activity, equivalent stability, higher DEB selectivity and a much lower xylene selectivity in comparison with ZSM-5. The catalytic performance of the IM-5 zeolite in the vapor phase process provides a new choice for the production of ethylbenzene. This journal is
- Chen, Junwen,Luo, Yibin,Shu, Xingtian,Wang, Yongrui,Zhai, Yunping
-
p. 18288 - 18298
(2021/06/03)
-
- Methanol to Aromatic Reaction over HZSM-5: Co-Effect Desilication and SiO2 Deposition
-
Abstract: In this work Si/HZSM-5-0.09M catalyst was prepared using desilication and regrowth of SiO2 method, which was characterized by XRF, XRD, SEM, NH3-TPD, and N2 adsorption/desorption. Meanwhile, the structure–activit
- Dong, Peng,Hui, Li,Ji, Dong,Li, Chunqiang,Li, Guixian,Zhao, Xinhong
-
p. 418 - 427
(2021/06/14)
-
- Bipyridinium and Phenanthrolinium Dications for Metal-Free Hydrodefluorination: Distinctive Carbon-Based Reactivity
-
The development of novel Lewis acids derived from bipyridinium and phenanthrolinium dications is reported. Calculations of Hydride Ion Affinity (HIA) values indicate high carbon-based Lewis acidity at the ortho and para positions. This arises in part from extensive LUMO delocalization across the aromatic backbones. Species [C10H6R2N2CH2CH2]2+ (R=H [1 a]2+, Me [1 f]2+, tBu [1 g]2+), and [C12H4R4N2CH2CH2]2+ (R=H [2 a]2+, Me [2 b]2+) were prepared and evaluated for use in the initiation of hydrodefluorination (HDF) catalysis. Compound [2 a]2+ proved highly effective towards generating catalytically active silylium cations via Lewis acid-mediated hydride abstraction from silane. This enabled the HDF of a range of aryl- and alkyl- substituted sp3(C?F) bonds under mild conditions. The protocol was also adapted to effect the deuterodefluorination of cis-2,4,6-(CF3)3C6H9. The dications are shown to act as hydride acceptors with the isolation of neutral species C16H14N2 (3 a) and C16H10Me4N2 (3 b) and monocationic species [C14H13N2]+ ([4 a]+) and [C18H21N2]+ ([4 b]+). Experimental and computational data provide further support that the dications are initiators in the generation of silylium cations.
- Burton, Katherine I.,Elser, Iris,Waked, Alexander E.,Wagener, Tobias,Andrews, Ryan J.,Glorius, Frank,Stephan, Douglas W.
-
supporting information
p. 11730 - 11737
(2021/07/16)
-
- Preliminary investigations on the catalytic hydrogenation of polycyclic aromatic hydrocarbons via WGSR
-
The water-gas shift reaction (WGSR) is a crucial reaction in the direct liquefaction of lignite in a syngas (CO + H2) system. In this study, anthracene was utilized as a polycyclic model compound of lignite, to which hydrogen is donated by the H2/D2 produced from CO and H2O/D2O via the WGSR. The results show that the model compound of the polycyclic aromatic hydrocarbon in coal (anthracene) undergoes partial cracking and polycondensation under non-hydrogen-donor conditions at 400 °C. In addition, WGSR catalyzed by NiO can generate hydrogen for the hydrogenation of anthracene. Comparing the mass spectra of deuterated products with those of conventional hydrogenation products by isotope labeling, the alkyl side chain positions of toluene, 1,4-xylene, methylnaphthalene, 1,1-diphenylethylene, methylanthracene and other compounds are prone to deuteration, enabling speculation of the main hydrogenation route of anthracene, which provides theoretical support for the catalytic hydrogenation in direct liquefaction of lignite in a syngas (CO + H2) system.
- Chen, Dabo,Gu, Jiale,Huang, Sheng,Li, Huan,Wu, Shiyong,Wu, Youqing
-
-
- Fabrication of a core-shell MFI?TON material and its enhanced catalytic performance for toluene alkylation
-
Core-shell MFI?TON composites were designed and synthesized as a highly shape-selective catalyst for toluene alkylation with methanol by passivating the nonselective acid sites and tuning the diffusion behavior. The synthesis parameters were comprehensively investigated, indicating the importance of the Si/Al ratio compatibility of the ZSM-5 and ZSM-22 components on the formation of a core-shell structure. The synthesis process was systemically traced, which allowed the formulation of a crystallization mechanism involving the oriented crystal growth and selective fusion steps during the secondary crystallization. As a result, the MFI zeolites as the core were fully covered by the TON zeolites as the shell, yielding spherical morphology. When applied to toluene alkylation with methanol, the core-shell MFI?TON composite exhibited significantly improved para-xylene selectivity in comparison with the original, unattached, and physically mixed catalysts. The enhanced catalytic behaviors of the core-shell MFI?TON composite could be ascribed to the effective suppression of para-xylene isomerization as a result of the passivated acid sites on the external surface and the improved diffusion time and distance for the intermediates inside the channels due to the unique structure. The synthesis method for the MFI?TON composite described herein may provide a generic platform for the design of core-shell zeolites with potentially broader applicability to other porous materials with advanced applications.
- Chen, Huimin,Chen, Zhiqiang,Li, Yong-Wang,Liu, Suyao,Ren, Jie,Wen, Xiaodong,Yang, Yong,Zhang, Huaike,Zhang, Liwei
-
p. 1281 - 1291
(2020/03/24)
-
- Methane Generation and Reductive Debromination of Benzylic Position by Reconstituted Myoglobin Containing Nickel Tetradehydrocorrin as a Model of Methyl-coenzyme M Reductase
-
Methyl-coenzyme M reductase (MCR), which contains the nickel hydrocorphinoid cofactor F430, is responsible for biological methane generation under anaerobic conditions via a reaction mechanism which has not been completely elucidated. In this work, myoglobin reconstituted with an artificial cofactor, nickel(I) tetradehydrocorrin (NiI(TDHC)), is used as a protein-based functional model for MCR. The reconstituted protein, rMb(NiI(TDHC)), is found to react with methyl donors such as methyl p-toluenesulfonate and trimethylsulfonium iodide with methane evolution observed in aqueous media containing dithionite. Moreover, rMb(NiI(TDHC)) is found to convert benzyl bromide derivatives to reductively debrominated products without homocoupling products. The reactivity increases in the order of primary > secondary > tertiary benzylic carbons, indicating steric effects on the reaction of the nickel center with the benzylic carbon in the initial step. In addition, Hammett plots using a series of para-substituted benzyl bromides exhibit enhancement of the reactivity with introduction of electron-withdrawing substituents, as shown by the positive slope against polar substituent constants. These results suggest a nucleophilic SN2-type reaction of the Ni(I) species with the benzylic carbon to provide an organonickel species as an intermediate. The reaction in D2O buffer at pD 7.0 causes a complete isotope shift of the product by +1 mass unit, supporting our proposal that protonation of the organonickel intermediate occurs during product formation. Although the turnover numbers are limited due to inactivation of the cofactor by side reactions, the present findings will contribute to elucidating the reaction mechanism of MCR-catalyzed methane generation from activated methyl sources and dehalogenation.
- Hayashi, Takashi,Miyazaki, Yuta,Oohora, Koji
-
supporting information
p. 11995 - 12004
(2020/09/15)
-
- PROCESSES FOR CONVERTING BENZENE AND/OR TOLUENE VIA METHYLATION
-
This disclosure provides improved processes for converting benzene/toluene via methylation with methanol/dimethyl ether for producing, e.g., p-xylene. In an embodiment, a process utilizes a methylation catalyst system comprising a molecular sieve catalyst and an auxiliary catalyst. The auxiliary catalyst comprises a metal element selected from Group 2, Group 3, the lanthanide series, the actinide series, and mixtures and combinations thereof. The auxiliary catalyst may comprise the oxide of the metal element. Deactivation of the molecular sieve catalyst can be reduced with the inclusion of the auxiliary catalyst in the methylation catalyst system.
- -
-
Paragraph 0085-0091
(2020/10/18)
-
- PROCESSES FOR CONVERTING BENZENE AND/OR TOLUENE VIA METHYLATION
-
This disclosure provides improved processes for converting benzene/toluene via methylation with methanol/dimethyl ether for producing, e.g., p-xylene. In an embodiment, a process comprises contacting a methylation agent feed with an aromatic hydrocarbon feed in the presence of a methylation catalyst in a methylation reactor at increased pressure. Reduced methylation catalyst deactivation can be achieved with increased pressure in the methylation reactor.
- -
-
Paragraph 0082-0085
(2020/10/20)
-
- Selective production of bio-based: Para -xylene over an FeOx -modified Pd/Al2O3catalyst
-
para-Xylene (PX) is a basic building block of polyethylene terephthalate, which is currently produced from petroleum resources. Developing a renewable route to PX is highly desirable to address both economic and environmental concerns. Several attempts used noble metal catalysts, e.g. Pd/Al2O3, to synthesize PX from biomass-derived 4-methyl-3-cyclohexene-1-carboxaldehyde (4-MCHCA), but suffered from a severe decarbonylation reaction, resulting in toluene as the main product. In this paper, we report an FeOx modification strategy to suppress the decarbonylation reaction on a Pd/Al2O3 catalyst, leading to a drastic shift in selectivity towards PX with a yield up to 81percent via a cascade dehydroaromatization-hydrodeoxygenation (DHA-HDO) pathway. Characterization and control experiments revealed that the electron density of Pd sites decreased in an FeOx-modified Pd/Al2O3 catalyst compared to Pd/Al2O3, thus tuning the preferential adsorption mode of the substrate from η2-(C,O), the key transition state of the decarbonylation reaction, to the η1-(O) mode that favors the hydrodeoxygenation process. Notably, this designed catalyst is highly stable and is readily applicable in the selective synthesis of a broad range of desired aromatic chemicals via the same DHA-HDO pathway from cyclohex-3-enecarbaldehyde derivatives. Overall, this work develops a controllable catalyst modification strategy that tailors an efficient catalyst for petroleum-independent bio-PX synthesis.
- Fu, Zaihui,Li, Changzhi,Meng, Qingwei,Pan, Xiaoli,Xiao, Yuxue,Zhang, Chao
-
p. 4341 - 4349
(2020/07/14)
-
- Effects of steam on toluene hydrogenation over a Ni catalyst
-
The catalytic toluene hydrogenation over Ni/SiO2 was carried out using H2 or a H2/H2O mixture. The toluene conversion and MCH selectivity were evaluated under partial steam pressures 0?10 kPa, at H2/t
- Atsumi, Ryosuke,Kobayashi, Keisuke,Xieli, Cui,Nanba, Tetsuya,Matsumoto, Hideyuki,Matsuda, Keigo,Tsujimura, Taku
-
-
- Nickel/Photoredox-Catalyzed Methylation of (Hetero)aryl Chlorides Using Trimethyl Orthoformate as a Methyl Radical Source
-
Methylation of organohalides represents a valuable transformation, but typically requires harsh reaction conditions or reagents. We report a radical approach for the methylation of (hetero)aryl chlorides using nickel/photoredox catalysis wherein trimethyl orthoformate, a common laboratory solvent, serves as a methyl source. This method permits methylation of (hetero)aryl chlorides and acyl chlorides at an early and late stage with broad functional group compatibility. Mechanistic investigations indicate that trimethyl orthoformate serves as a source of methyl radical via β-scission from a tertiary radical generated upon chlorine-mediated hydrogen atom transfer.
- Kariofillis, Stavros K.,Shields, Benjamin J.,Tekle-Smith, Makeda A.,Zacuto, Michael J.,Doyle, Abigail G.
-
supporting information
p. 7683 - 7689
(2020/04/22)
-
- Visible-Light-Induced Ni-Catalyzed Radical Borylation of Chloroarenes
-
A highly selective and general photoinduced C-Cl borylation protocol that employs [Ni(IMes)2] (IMes = 1,3-dimesitylimidazoline-2-ylidene) for the radical borylation of chloroarenes is reported. This photoinduced system operates with visible light (400 nm) and achieves borylation of a wide range of chloroarenes with B2pin2 at room temperature in excellent yields and with high selectivity, thereby demonstrating its broad utility and functional group tolerance. Mechanistic investigations suggest that the borylation reactions proceed via a radical process. EPR studies demonstrate that [Ni(IMes)2] undergoes very fast chlorine atom abstraction from aryl chlorides to give [NiI(IMes)2Cl] and aryl radicals. Control experiments indicate that light promotes the reaction of [NiI(IMes)2Cl] with aryl chlorides generating additional aryl radicals and [NiII(IMes)2Cl2]. The aryl radicals react with an anionic sp2-sp3 diborane [B2pin2(OMe)]- formed from B2pin2 and KOMe to yield the corresponding borylation product and the [Bpin(OMe)]?- radical anion, which reduces [NiII(IMes)2Cl2] under irradiation to regenerate [NiI(IMes)2Cl] and [Ni(IMes)2] for the next catalytic cycle.
- Tian, Ya-Ming,Guo, Xiao-Ning,Krummenacher, Ivo,Wu, Zhu,Nitsch, J?rn,Braunschweig, Holger,Radius, Udo,Marder, Todd B.
-
supporting information
p. 18231 - 18242
(2020/11/02)
-
- Preparation method of bio-based P-xylene
-
The invention relates to a preparation method of bio-based PX, wherein the bio-based PX is prepared through a reaction of 2,5-hexanedione and ethylene, and the 2,5-hexanedione is bio-based 2,5-hexanedione obtained by biomass conversion. The method has the advantages of short reaction path, simplicity in operation and easiness in large-scale preparation, provides advanced technical support for industrial production of bio-based PX, and has wide application prospect.
- -
-
Paragraph 0024; 0025; 0076-0239
(2020/04/22)
-
- Single site MIL-101 for novel low-temperature liquid-phase toluene methylation
-
Abstract: P-xylene is one of petrochemical products eagerly in demand. Until recently, the process for preparing of p-xylene was done via gas-phase toluene methylation reaction at high temperature using a strong acid catalyst. In this work, high surface area, shape-selective and single-site MIL-101(Cr) was used as a catalyst to perform toluene methylation reaction in a liquid phase at low reaction temperature (60-120?°C). Toluene conversion and p-xylene selectivity are up to 50% and 90%, respectively. Under the optimum operating conditions; 1:1 toluene: methanol molar ratio, the reaction temperature is 120?°C. The catalyst was synthesized via the hydrothermal method and the MIL-101 structure was confirmed by different analytical techniques: TGA, XRD, FTIR and BET surface area. The remarkably high toluene conversion and xylene selectivity at a low reaction temperature, in comparison to previous research, was attributed to the suppression of side reactions that could convert methanol to linear hydrocarbons, and to the inhibition of p-xylene isomerization. This suppression can be attributed to the single site properties and to the uniform pore size distribution of the prepared MIL 101 catalyst. Graphic abstract: Synthesis and characterization of single-site MIL-101(Cr) were used as a catalyst for toluene methylation reaction in a liquid phase at low reaction temperature (60–120 °C). The results suggest that toluene conversion and p-xylene selectivity are up to 50% and 90%, respectively, under the optimum operating conditions; 1:1 toluene: methanol molar ratio, the reaction temperature is 120 °C.[Figure not available: see fulltext.].
- Abd El Salam, Howaida Mamdouh,Abd El-Hafiz, Dalia Radwan
-
-
- METHOD FOR AROMATIZATION OF LIGHT ALKANES
-
A method for aromatization of light alkanes, comprising: subjecting the light alkanes to dehydroaromatization reaction in the presence of aromatization catalysts including carriers and metal active components supported on the carriers, the metal active components include platinum, the carriers include zeolites and binders, and at least 80 wt. % of the metal active components are distributed on the zeolites. The method of the present disclosure may increase yield of the target product—aromatic hydrocarbons, and the regenerated catalyst can still maintain high catalytic performance. In addition, the method of the present disclosure can meet the requirements of industrial applications.
- -
-
Page/Page column 4-5
(2020/07/16)
-
- The Selective Conversion of Methyl and Ethyl Acetate to High Content Alkyl Aromatic Hydrocarbons over H-ZSM5
-
Abstract: This research is devoted to a catalytic process using the H-ZSM5 catalyst for the conversion of methyl and ethyl acetate to hydrocarbon aromatics. These reactions are carried out in a fixed bed reactor under atmospheric pressure at 370°C. The distribution of products was measured by GC-Mass spectrometer. The variation of weight hourly space velocity (WHSV) on the conversion of these esters to aromatic hydrocarbons showed a significant effect on carbon distribution. The deactivation catalyst by time was monitored using product selectivity and conversion. The production of alkyl and poly alkyl aromatic compounds was formed under controlled conditions. The advantages of these methods are the formation of a higher concentration of octane number booster poly alkyl aromatic compounds (mono-aromatics) from esters as starting materials. Moreover, the catalyst lifetime on stream was investigated and exhibited longer catalyst lifetime for ethyl acetate conversion than methyl acetate.
- Dabbagh, H. A.,Hassanpour, J.
-
p. 1284 - 1290
(2020/12/02)
-
- Ruthenium-catalyzed selective hydroboronolysis of ethers
-
A ruthenium-catalyzed reaction of HBpin with substituted organic ethers leads to the activation of C?O bonds, resulting in the formation of alkanes and boronate esters via hydroboronolysis. A ruthenium precatalyst, [Ru (p-cymene)Cl]2Cl2 (1), is employed, and the reactions proceed under neat conditions at 135 °C and atmospheric pressure (ca. 1.5 bar at 135 °C). Unsymmetrical dibenzyl ethers undergo selective hydroboronolysis on relatively electron-poor C?O bonds. In arylbenzyl or alkylbenzyl ethers, C?O bond cleavage occurs selectively on CBn?OR bonds (Bn = benzyl); in alkylmethyl ethers, selective deconstruction of CMe?OR bonds leads to the formation of alkylboronate esters and methane. Cyclic ethers are also amenable to catalytic hydroboronolysis. Mechanistic studies indicated the immediate in situ formation of a mono-hydridobridged dinuclear ruthenium complex [{(η6-p-cymene)RuCl}2(μ?H?μ?Cl)] (2), which is highly active for hydroboronolysis of ethers. Over time, the dinuclear species decompose to produce ruthenium nanoparticles that are also active for this transformation. Using this catalytic system, hydroboronolysis could be applied effectively to a very large scope of ethers, demonstrating its great potential to cleave C?O bonds in ethers as an alternative to traditional hydrogenolysis.
- Kaithal, Akash,Kalsi, Deepti,Krishnakumar, Varadhan,Pattanaik, Sandip,Bordet, Alexis,Leitner, Walter,Gunanathan, Chidambaram
-
p. 14390 - 14397
(2020/12/21)
-
- Hydrodehalogenation of alkyl halides catalyzed by a trichloroniobium complex with a redox active α-diimine ligand
-
A high-valent d0 niobium(v) complex, (α-diimine)NbCl3 (1), bearing a dianionic redox-active α-diimine ligand served as a catalyst for a hydrodehalogenation reaction of alkyl halides in the presence of PhSiH3. During the catalytic reaction, the redox-active α-diimine ligand allowed the complex to reversibly release and accept one-electron through switching its coordination mode between a dianionic folded form and a monoanionic planar one.
- Nishiyama, Haruka,Hosoya, Hiromu,Parker, Bernard F.,Arnold, John,Tsurugi, Hayato,Mashima, Kazushi
-
p. 7247 - 7250
(2019/07/02)
-
- Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides
-
For the first time, by using H3PO3/I2 system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H3PO3, benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.
- Gao, Jing,Han, Li-Biao,Ma, Yonghao,Tang, Zilong,Wu, Xiaofang,Xiao, Jing
-
p. 22343 - 22347
(2019/07/31)
-
- Catalytic performance of a phosphorus-modified H-IM-5@meso-SiO2 composite in the alkylation of toluene with methanol
-
Herein, a core-shell H-IM-5@meso-SiO2 hybrid material was synthesized by reversing the charge of the external surface of IM-5 crystals to a positive charge by PDDA that could induce an oriented self-assembly formation of the meso-SiO2 shell. The as-synthesized H-IM-5@meso-SiO2 composite was thereafter modified with phosphorus species to further enhance the selectivity of the target product. The sample morphology and structure were analyzed by electron microscopy technology, XRD, XPS and N2 adsorption-desorption. The effects of the meso-SiO2 shell and phosphorus species on sample acidity were investigated by NH3-TPD, FTIR spectroscopy and solid-state NMR measurements. The catalytic properties and characterization results revealed that the meso-SiO2 shell could passivate the external surface acids of the H-IM-5 crystals. The phosphorus modification could simultaneously adjust the surface acidity as well as the size of the pores and pore-openings. The TPD analysis of xylene showed that the sample surface acidity and geometric factors played important roles in the diffusion process of the diffusing molecules.
- Yi, Dezhi,Meng, Xuan,Liu, Naiwang,Shi, Li
-
p. 11758 - 11770
(2019/07/31)
-
- Synthesized high-silica hierarchical porous ZSM-5 and optimization of its reaction conditions in benzene alkylation with methanol
-
In our present work, the high-silica hierarchical porous ZSM-5 with appropriate Br?nsted acidity and hierarchical porous structure was synthesized by sol-gel method for continuously catalytic conversion of benzene alkylation with methanol to xylene. The effects of temperature, pressure, benzene/methanol molar ratio and weight hour space velocity (WHSV) on the catalytic performance of the catalyst were investigated as well. As a result, the high-silica hierarchical porous ZSM-5 showed great performance as the yield of xylene was up to 41.1% under the optimum reaction conditions (500 °C, 0.1 MPa, Mbenzene/Mmethanol = 1:1.5 and WHSV = 4 h?1), while the selectivity to by-product, ethylbenzene, was well suppressed (below 0.1%). In addition, the catalyst structure and properties were characterized by the means of XRD, IR, TPD, SEM, TEM and N2 physical adsorption technologies.
- Rui, Jiayao,Lyu, Jinghui,Hu, Hualei,Zhang, Qunfeng,Wang, Qingtao,Li, Xiaonian
-
p. 757 - 761
(2018/11/23)
-
- Palladium oxide nanoparticles supported on graphene oxide: A convenient heterogeneous catalyst for reduction of various carbonyl compounds using triethylsilane
-
Palladium oxide nanoparticles supported on graphene oxide - triethylsilane was found to be an effective reductive system for a broad range of reduction processes, including the reduction of various carbonyl compounds such as aromatic aldehydes to their corresponding alcohols or methyl arene compounds, aromatic ketones to their respective alcohols or saturated compounds, aromatic acyl chlorides to their reduced compounds. The desired products were obtained in good to excellent yields under mild conditions. The heterogeneous environmentally friendly catalyst can be easily separated from the reaction mixture through a simple filtration, facilitating purification of the prepared compounds.
- Mirza-Aghayan, Maryam,Kalantari, Meisam,Boukherroub, Rabah
-
-
- Chemoselective Hydrodeoxygenation of Carboxylic Acids to Hydrocarbons over Nitrogen-Doped Carbon-Alumina Hybrid Supported Iron Catalysts
-
The establishment of catalyst systems for the chemoselective hydrodeoxygenation (HDO) of carboxylic acids to hydrocarbons, such as the HDO of long-chain fatty acids to alkanes, is important for biomass to biofuel conversion. As the most abundant and probably the cheapest transition metal on the earth, iron is a promising non-noble-metal alternative to precious metals for large-scale conversion of biomass. However, it usually suffers from unsatisfactory activity. In this work, a nitrogen-doped carbon-alumina hybrid supported iron (Fe-N-C@Al2O3) catalyst is established for chemoselective HDO of carboxylic acids to hydrocarbons. By using stearic acid HDO as the model reaction, n-octadecane and n-heptadecane are produced with yields of 91.9% and 6.0%, respectively. Triglycerides can also be converted into liquid alkanes with a total molar yield of >92%. In addition, the iron catalyst can chemoselectively catalyze the HDO of the carboxylic acid group in the presence of other functional groups such as an aromatic ring. This chemoselectivity has rarely been seen before because the aromatic ring is usually more easily hydrogenated in comparison to HDO of the carboxylic acid group. The characterization results showed that both the formation of a nitrogen-doped carbon-alumina hybrid and the iron loading are important for the Lewis basicity of these catalysts, in order to adsorb the acid substrates. The addition of melamine as the nitrogen precursor during pyrolysis eliminates undesired reactions between the iron precursor and alumina support to form an inactive hercynite phase, leading to the formation of an Fe3C active phase for the hydrogenation of -COOH to -CH2OH and the hybrid of N-C and alumina for the HDO of -CH2OH to -CH3.
- Li, Jiang,Zhang, Junjie,Wang, Shuai,Xu, Guangyue,Wang, Hao,Vlachos, Dionisios G.
-
p. 1564 - 1577
(2019/02/03)
-
- Method for synthesizing aromatic hydrocarbon compound
-
The invention relates to a method for preparing an aromatic compound through dehydrogenating a cycloalkane or cycloalkene compound in the presence of a palladium or palladium polymetal co-loaded catalyst. According to the method, the aromatic compound is synthesized at a low temperature under anaerobic conditions, a high-activity high-selectivity catalyst is developed, and an industrial moderate preparation method for the aromatic compound is established.
- -
-
Paragraph 0026; 0027
(2019/03/26)
-
- Synthesis of mesoporous ZSM-5 zeolites and catalytic cracking of ethanol and oleic acid into light olefins
-
Conversion of biomass-derived chemicals into light olefins is a promising method to maintain sustainable development of light olefin industry. In this study, three mesoporous ZSM-5 zeolites (MZSM-5-A, MZSM-5-B and MZSM-5-C) with major pore diameter about 4.8 nm, 16 nm and 22 nm were synthesized using a hydrothermal method by utilizing different templates. The catalytic activity of catalysts was studied by catalytic cracking of ethanol and oleic acid. The influence of reaction temperature on conversion and product selectivity was investigated. The characterization of ZSM-5 samples showed that the orders of the external surface area and mesopore volume were MZSM-5-C > MZSM-5-B > MZSM-5-A > conventional HZSM-5. In ethanol to light olefin reaction, MZSM-5-C achieved the highest light olefin yield (318.3 mL g?1) and ethylene selectivity (42.3%) at 400 °C. In oleic acid to light olefin reaction, MZSM-5-B achieved a complete conversion of oleic acid at 500 °C, and obtained the highest light olefin selectivity (38.1%) at 550 °C. The difference may be relevant to the size and chemical structure of feedstock molecular as well as the acidity of catalysts. Regardless of ethanol or oleic acid as feedstock, introduction of mesopore in zeolites significantly enhanced the light olefin yield and selectivity.
- Zhao, Tingting,Li, Fuwei,Yu, Hongchang,Ding, Shilei,Li, Zhixia,Huang, Xinyuan,Li, Xiang,Wei, Xiaohan,Wang, Zhenlin,Lin, Hongfei
-
p. 101 - 110
(2019/02/24)
-
- Catalytic reduction of aryl trialkylammonium salts to aryl silanes and arenes
-
A new approach for the reduction of aryl ammonium salts to arenes or aryl silanes using nickel catalysis is reported. This method displays excellent ligand-controlled selectivity based on the N-heterocyclic carbene (NHC) ligand employed. Utilizing a large NHC in non-polar solvents generates aryl silanes, while small NHCs in polar solvents promote reduction to arenes. Several classes of aryl silanes can be accessed from simple aniline building blocks, including those useful for cross-couplings, oxidations, and halogenations. The reaction conditions are mild, functional group tolerant, and provide efficient access to a variety of benzene derivatives.
- Rand, Alexander W.,Montgomery, John
-
p. 5338 - 5344
(2019/05/29)
-
- PROCESS FOR PREPARING A CATALYST FOR ALKANE AROMATIZATION
-
The present invention relates to a process for preparing a catalyst for alkane aromatization providing high % conversion, high yield, high selectivity of aromatics, and high selectivity of p-xylene in xylene, wherein said process comprises the following steps: (a) contacting a zeolite with a solution of group IIIA metal salt; (b) contacting the zeolite obtained from step (a) with the solution of metal salt selected from a group VIIB metal, a group VB metal, or a mixture thereof; and (c) contacting the zeolite obtained from step (b) with alkoxysilane, characterized in that the solution of salt in step (b) comprising a glycol solvent as a reducing agent under a basic condition, and step (b) is operated at the temperature higher than 120° C.
- -
-
Paragraph 0081-0084
(2019/09/06)
-
- Chemical Imaging of the Binder-Dependent Coke Formation in Zeolite-Based Catalyst Bodies During the Transalkylation of Aromatics
-
The choice of binder material, added to a zeolite-based catalyst body, can significantly influence the catalyst performance during a reaction, i. e. its deactivation and selectivity. In this work the influence of the binder in catalyst extrudates on the formation of hydrocarbon deposits was explored during the transalkylation of toluene with 1,2,4-trimethylbenzene (1,2,4-TMB). Using in situ UV-vis micro-spectroscopy and ex situ confocal fluorescence microscopy approach, coke species were revealed to predominantly form on the rim of zeolite crystals within Al2O3-bound extrudates. It was found that this was due to Al migration between the zeolite crystals and the Al2O3-binder creating additional acid sites near the zeolite external surface. In contrast, minimal isomerization of 1,2,4-TMB in the SiO2-bound extrudate allowed greater access to the zeolite internal pore network, creating a more homogeneous coke distribution throughout the zeolite crystals.
- Verkleij, Suzanna P.,Whiting, Gareth T.,Pieper, Denise,Parres Esclapez, Sonia,Li, Shiwen,Mertens, Machteld M.,Janssen, Marcel,Bons, Anton-Jan,Burgers, Martijn,Weckhuysen, Bert M.
-
p. 4788 - 4796
(2019/09/17)
-
- Fluidized bed apparatus/and method for the production of para-xylene by methanol and/or dimethyl ether and benzene and low carbon olefins
-
Disclosed are a turbulent fluidized bed reactor, device and method for preparing para-xylene and co-producing light olefins from methanol and/or dimethyl ether and benzene, resolving or improving the competition problem between an MTO reaction and an alkylation reaction during the process of producing para-xylene and co-producing light olefins from methanol and/or dimethyl ether and benzene, and achieving a synergistic effect between the MTO reaction and the alkylation reaction. By controlling the mass transfer and reaction, competition between the MTO reaction and the alkylation reaction is coordinated and optimized to facilitate a synergistic effect of the two reactions, so that the conversion rate of benzene, the yield of para-xylene, and the selectivity of light olefins are increased. The turbulent fluidized bed reactor comprises a first reactor feed distributor and a plurality of second reactor feed distributors; the first reactor feed distributor and the plurality of second reactor feed distributions are sequentially arranged along the gas flow direction in a reaction zone of the turbulent fluidized bed reactor.
- -
-
Paragraph 0122-0161
(2020/04/04)
-
- A Zeolite Family Nonjointly Built from the 1,3-Stellated Cubic Building Unit
-
From a technological point of view, the synthesis of new high-silica zeolites is of prime importance owing to their high potential as industrial catalysts and catalyst supports. Two such materials have been synthesized which are made up of the 1,3-stellated cubic unit (hexahedral ([4254]) bre unit) as a secondary building unit, with the aid of existing imidazolium-based structure-directing agents under “excess fluoride” conditions. One of them, denoted PST-21, is the first aluminosilicate zeolite consisting of 9-ring apertures solely; it displays exceptional activity towards steering the skeletal isomerization of 1-butene to isobutene and bridges the gap between small- and medium-pore structures. A series of hypothetical structures are also described that are nonjointly built from the bre unit; all of these structures are chemically feasible and will thus be helpful in designing the synthesis of novel zeolites containing 9-ring and/or 10-ring channels.
- Jo, Donghui,Park, Gi Tae,Shin, Jiho,Hong, Suk Bong
-
supporting information
p. 2199 - 2203
(2018/02/06)
-
- Process for Producing Paraxylene by Methylation of Benzene and/or Toluene
-
A process is described for producing paraxylene, in which an aromatic hydrocarbon feedstock comprising benzene and/or toluene is contacted with an alkylating reagent comprising methanol and/or dimethyl ether in an alkylation reaction zone under alkylation conditions in the presence of an alkylation catalyst to produce an alkylated aromatic product comprising xylenes. The alkylation catalyst comprises a molecular sieve having a Constraint Index≤5, and the alkylation conditions comprise a temperature less than 500° C. Paraxylene may then be recovered from the alkylated aromatic product.
- -
-
Paragraph 0041-0043
(2018/04/20)
-
