ChemInform Abstract: Reactions of Aromatic Hydrocarbons Over Zeolite β.

Ratnasamy, P.; Bhat, R.N.; Pokhriyal, S.K.; Hegde, S.G.; Kumar, Rajiv

doi:10.1002/chin.198952054

Cited by 6 publications

(6 citation statements)

References 1 publication

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“…This reaction has been extensively studied over zeolites such as ZSM5, mordenite, zeolite Y, b zeolite, SSZ-33, TNU-9, etc. [1][2][3][4][5][6][7][8][9]. In most of these cases, the concentrations of the xylene isomers produced were close to the thermodynamic equilibrium ratios (23.5% p-xylene, 52.1% m-xylene and 24.4% o-xylene at 700 K) [4].…”

Section: Introductionmentioning

confidence: 99%

Disproportionation of Toluene on Monoliths Washcoated with Metal Oxide Modified ZSM5

Mitra

Kunzru

2011

Catal Lett

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Monoliths washcoated with ZSM5 and metal oxide (MgO, CaO, La 2 O 3 or CeO 2 ) modified ZSM5 were prepared, characterized and studied for toluene disproportionation. An improvement in the yield of the desired p-xylene isomer was obtained by using monoliths coated with metal oxide-modified ZSM5. The enhancement in p-xylene yield depended on the type of modifier, metal loading and the washcoat thickness on the monolith. The 10% LaZSM5 coated monolith having an average washcoat thickness of 23 lm showed the highest p-xylene yield.

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Section: Introductionmentioning

confidence: 99%

Disproportionation of Toluene on Monoliths Washcoated with Metal Oxide Modified ZSM5

Mitra

Kunzru

2011

Catal Lett

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“…However, as a result of important application to individual xylene isomers, it is necessary that mixed xylene is separated out through adsorption separation and isomerization reaction processes to obtain desired xylene isomers. In fact, the remarkable advances in p-xylene production from m-xylene isomerization using zeolite catalyst have been achieved over the last several decades [16][17][18][19][20]; meanwhile, the separation of xylene isomers through zeolite adsorbents has also gained considerable interest. The great success of zeolites as catalysts and adsorbents is exactly due to their unique shape selective properties from pore structure [21,22].…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Diffusion of Xylene Isomers on Mesoporous Beta Zeolite

Song

et al. 2015

Catalysts

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Abstract:A systematic and detailed analysis of adsorption and diffusion properties of xylene isomers over Beta zeolites with different mesoporosity was conducted. Adsorption isotherms of xylene isomers over microporous and mesoporous Beta zeolites through gravimetric methods were applied to investigate the impact of mesopores inside Beta zeolites on the adsorption properties of xylene isomers in the pressure range of lower 20 mbar. It is seen that the adsorption isotherms of three xylene isomers over microporous and mesoporous Beta zeolites could be successfully described by the single-site Toth model and the dual-site Toth model, respectively. The enhanced adsorption capacities and decreased Henry's constants (KH) and the initial heats of adsorption (Qst) for the all xylene isomers are observed after the introduction of mesopores in the zeolites. For three xylene isomers, the order of Henry's constant is o-xylene > m-xylene > p-xylene, whereas the adsorption capacities of Beta zeolite samples for xylene isomers execute the following order of o-xylene > p-xylene > m-xylene, due to the comprehensive effects from the molecular configuration and electrostatic interaction. At the same time, the diffusion properties of xylene isomers in the mesoporous Beta zeolites were also studied through the desorption curves measured by the zero length column (ZLC) method at 333-373 K. It turned out that the effective diffusion time constant (Deff/R 2 ) is a growing trend with the increasing mesoporosity, whereas the tendency of the activation energy is just the reverse, indicating the contribution of mesopores to facilitate molecule diffusion by shortening diffusion paths and reducing diffusion resistances. Moreover, the diffusivities of three xylene isomers in all Beta zeolites follow an order of p-xylene > m-xylene > o-xylene OPEN ACCESSCatalysts 2015, 5 2099 as opposed to KH, conforming the significant effects of adsorbate-adsorbent interaction on the diffusion.

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“…The same catalytic activities, methylation and demethylation, have been reported on an acidic large-pore zeolite. H-Beta catalyzed methylation of toluene with methanol [97,98] and demethylation of hexamethylbenzene under nitrogen [99] or polymethylbenzenes under helium [100]. Reaction of hexamethylbenzene with benzene over the tungsten cluster in the absence of methanol yielded toluene with 9% selectivity; indicating intermolecular transfer of the methyl substituents.…”

Section: Methylation Of Toluene (Equationmentioning

confidence: 99%

Catalytic Reactions over Halide Cluster Complexes of Group 5–7 Metals

Nagashima

Kamiguchi

Chihara

2014

Metals

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Halide clusters of Group 5-7 metals develop catalytic activity above 150-250 °C, and the activity is retained up to 350-450 °C by taking advantage of their thermal stability, low vapor pressure, and high melting point. Two types of active site function: the solid Brønsted acid site and a coordinatively unsaturated site that catalyzes like the platinum metals do. Various types of catalytic reactions including new reactions and concerted catalyses have been observed over the clusters: hydrogenation, dehydrogenation, hydrogenolysis, isomerization of alkene and alkyne, and alkylation of toluene, amine, phenol, and thiol. Ring-closure reactions to afford quinoline, benzofuran, indene, and heterocyclic common rings are also catalyzed. Beckmann rearrangement, S-acylation of thiol, and dehydrohalogenation are also catalyzed. Although the majority of the reactions proceed over conventional catalysts, closer inspection shows some conspicuous features, particularly in terms of selectivity. Halide cluster catalysts are characterized by some aspects: cluster counter anion is too large to abstract counter cation from the protonated reactants, cluster catalyst is not poisoned by halogen and sulfur atoms. Among others, cluster catalysts are stable at high temperatures up to 350-450 °C. At high temperatures, apparent activation energy decreases, and hence weak acid can be a catalyst without decomposing reactants. OPEN ACCESSMetals 2014, 4 236

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ChemInform Abstract: Reactions of Aromatic Hydrocarbons Over Zeolite β.

Cited by 6 publications

References 1 publication

Disproportionation of Toluene on Monoliths Washcoated with Metal Oxide Modified ZSM5

Disproportionation of Toluene on Monoliths Washcoated with Metal Oxide Modified ZSM5

Adsorption and Diffusion of Xylene Isomers on Mesoporous Beta Zeolite

Catalytic Reactions over Halide Cluster Complexes of Group 5–7 Metals

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