Catalytic Transformation of 1,3,5-Trimethylbenzene over a USY Zeolite Catalyst

Tukur, Nasiru M.; Al-Khattaf, S.

doi:10.1021/ef7002602

Cited by 25 publications

(15 citation statements)

References 22 publications

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“…The catalytic transformation of 1,3,5-TMB was applied as a probing reaction for the hierarchical EU-1 zeolites, which is a complex reaction including mainly isomerization and disproportionation. 16,[18][19][20] Moreover, the products of these reactions can react with each other and with the original reactants as well. 16 The conversion of bulky molecules tends to be more diffusion controlled, because the majority of the active sites of the zeolite are within its pores.…”

Section: 35-tmb Adsorption and Catalytic Transformationmentioning

confidence: 99%

Probing the pore structure of hierarchical EU-1 zeolites by adsorption of large molecules and through catalytic reaction

Guo

Hao

et al. 2020

Journal of Chemical Research

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The adsorption of toluene and 1,3,5-trimethylbenzene and the catalytic transformation of 1,3,5-trimethylbenzene are applied as probing approaches to characterize the pore system of hierarchical EU-1 zeolites prepared using organofunctionalized fumed silica as the silicon source. The adsorption and diffusion of toluene and 1,3,5-trimethylbenzene are significantly improved in the hierarchical EU-1 zeolites compared with the conventional microporous EU-1 zeolite. The adsorption kinetics of toluene and 1,3,5-trimethylbenzene suggested that introducing mesopores significantly increases the rate of adsorption and improved the diffusion of large molecules. In the catalytic transformation of 1,3,5-trimethylbenzene, the conversion of 1,3,5-trimethylbenzene on the hierarchical EU-1 zeolites is doubled compared with the conventional microporous EU-1 zeolite, due to the improved diffusion of bulky molecules and enhanced accessibility of active sites in the hierarchical EU-1 structure. Although isomerization is the main reaction, differences are observed in the product ratios of isomerization to disproportionation between the hierarchical EU-1 zeolites and the microporous counterpart with different times on stream. The transformation of 1,3,5-trimethylbenzene over the hierarchical EU-1 zeolites has a higher isomerization to disproportionation ratio than that over the microporous EU-1 zeolite; this is due to the increased mesoporosity.

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Section: 35-tmb Adsorption and Catalytic Transformationmentioning

confidence: 99%

Probing the pore structure of hierarchical EU-1 zeolites by adsorption of large molecules and through catalytic reaction

Guo

Hao

et al. 2020

Journal of Chemical Research

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“…showed that transalkylation and disproportionation mainly occur on strong acid sites, while isomerization can take place on weak acid sites. Isomerization reactions can decrease the p ‐xylene selectivity and transform the 1,2,4‐TMB to less reactive and more bulky 1,3,5‐TMB or 1,2,3‐TMB [32–36] . Furthermore, the performance of the zeolite catalyst during the transalkylation reaction is also dependent on the reaction conditions that are used.…”

Section: Introductionmentioning

confidence: 99%

High‐Pressure Operando UV‐Vis Micro‐Spectroscopy of Coke Formation in Zeolite‐based Catalyst Extrudates during the Transalkylation of Aromatics

Verkleij

Whiting

Esclapez³

et al. 2020

ChemCatChem

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The performance of zeolite‐based catalyst extrudates can be largely influenced by the choice of binder material. To investigate these binder effects in zeolite‐based catalyst extrudates in more detail, high spatiotemporal resolution techniques need to be further developed and employed. In this work, we present a new methodology to investigate binder effects in catalyst extrudates at different reaction pressures using operando UV‐vis diffuse reflectance (DR) micro‐spectroscopy coupled with on‐line gas chromatography. We have studied mm‐sized zeolite H‐ZSM‐5‐containing extrudates with either Al2O3 or SiO2 binder material, during the transalkylation of toluene with 1,2,4‐trimethylbenzene at 450 °C and at a pressure of either 1 or 5 bar. Using this technique, it was revealed that the binder material significantly influenced catalyst deactivation at different reaction pressures. By subsequent mapping of the cross sections of the cylindrical catalyst extrudates using UV‐vis micro‐spectroscopy, it was shown that the SiO2‐bound extrudate formed poly‐aromatic coke molecules homogeneously throughout the entire extrudate, whereas for the Al2O3‐bound extrudate a coke ring formed that moved inwards with increasing reaction time. Notably, the developed methodology is not limited to the transalkylation reaction, and can also be used to gain more insight into binder effects during a variety of important catalytic reactions.

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“…[13][14][15] However, it was found that medium-pore zeolites, like ZSM-5, have a higher selectivity towards p-xylene. [21][22][23] However, direct visual evidence of this phenomena is still missing. Previously, it has been shown that transalkylation and disproportionation mainly occur on strong acid sites, while isomerization can take place on weak acid sites.…”

Section: Introductionmentioning

confidence: 99%

“…[19,20] Finally, it has been reported that the more bulky 1,3,5-TMB and 1,2,3-TMB, formed by the isomerization of 1,2,4-TMB, diffuse slower through medium-pore zeolite due to steric constrains and will mainly react at the surface of the zeolite. [21][22][23] However, direct visual evidence of this phenomena is still missing.…”

Section: Introductionmentioning

confidence: 99%

Chemical Imaging of the Binder‐Dependent Coke Formation in Zeolite‐Based Catalyst Bodies During the Transalkylation of Aromatics

et al. 2019

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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 Al 2 O 3 -bound extrudates. It was found that this was due to Al migration between the zeolite crystals and the Al 2 O 3binder creating additional acid sites near the zeolite external surface. In contrast, minimal isomerization of 1,2,4-TMB in the SiO 2 -bound extrudate allowed greater access to the zeolite internal pore network, creating a more homogeneous coke distribution throughout the zeolite crystals.

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Catalytic Transformation of 1,3,5-Trimethylbenzene over a USY Zeolite Catalyst

Cited by 25 publications

References 22 publications

Probing the pore structure of hierarchical EU-1 zeolites by adsorption of large molecules and through catalytic reaction

Probing the pore structure of hierarchical EU-1 zeolites by adsorption of large molecules and through catalytic reaction

High‐Pressure Operando UV‐Vis Micro‐Spectroscopy of Coke Formation in Zeolite‐based Catalyst Extrudates during the Transalkylation of Aromatics

Chemical Imaging of the Binder‐Dependent Coke Formation in Zeolite‐Based Catalyst Bodies During the Transalkylation of Aromatics

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