Phenomena Based Process Intensification of Toluene Methylation for Sustainable Para-xylene Production

Toluene methylation with methanol to produce xylene has been widely investigated. A simultaneous side reaction of methanol-to-olefin over zeolites is hard to avoid, resulting in an unsatisfactory methylation efficiency. Here, CO2 and H2 replace methanol in toluene methylation over a class of ZnZrOx–ZSM-5 (ZZO-Z5) dual-functional catalysts. Results demonstrate that the reactive methylation species (H3CO*; * represents a surface species) are generated more easily by CO2 hydrogenation than by methanol dehydrogenation. Catalytic performance tests on a fixed-bed reactor show that 92.4% xylene selectivity in CO-free products and 70.8% para-xylene selectivity in xylene are obtained on each optimized catalyst. Isotope effects of H2/D2 and CO2/13CO2 indicate that xylene product is substantially generated from toluene methylation rather than disproportionation. A mechanism involving generation of reactive methylation species on ZZO by CO2 hydrogenation and migration of the methylation species to Z5 pore for the toluene methylation to form xylene is proposed.

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Intensification of an Irreversible Process Using Reactive Distillation – Simulation Studies

International Journal for Research in Applied Science and Engineering Technology ◽

10.22214/ijraset.2021.38870 ◽

2021 ◽

Vol 9 (11) ◽

pp. 625-634

Author(s):

Shuwana Tasleem

Keyword(s):

Irreversible Process ◽

Reactive Distillation ◽

Process Intensification ◽

Aspen Plus ◽

Reflux Ratio ◽

Simulation Studies ◽

Toluene Methylation ◽

Xylene Isomers ◽

Distillation Simulation ◽

Steady State Simulation

Abstract: In this study, a steady state simulation of the process for the production of xylene isomers by reactive distillation was performed using Aspen Plus software. The simulations were aimed studying the parameters like number of stages in the different sections of the RD column, reflux ratio, and the boil-up ratio, which maximize the conversion of Toluene and improves the selectivity and yield of the p- Xylene. Keywords: Reactive Distillation, Process Intensification, Toluene Methylation, Aspen Plus, Simulation Studies,

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Toluene methylation to para-xylene

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-018-7228-5 ◽

2018 ◽

Vol 135 (3) ◽

pp. 1723-1732 ◽

Cited By ~ 7

Author(s):

Mahdi Abdi-khanghah ◽

Abdullah A. A. A. Alrashed ◽

Touba Hamoule ◽

Reza Mosayebi Behbahani ◽

Marjan Goodarzi

Keyword(s):

Para Xylene ◽

Toluene Methylation

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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

Molecules ◽

10.3390/molecules24193462 ◽

2019 ◽

Vol 24 (19) ◽

pp. 3462 ◽

Cited By ~ 2

Author(s):

Yiren Wang ◽

Yang Chang ◽

Min Liu ◽

Anfeng Zhang ◽

Xinwen Guo

Keyword(s):

Physical Adsorption ◽

Catalytic Performance ◽

Acid Sites ◽

General Strategy ◽

X Ray Diffraction ◽

In Situ Modification ◽

Para Xylene ◽

Toluene Methylation ◽

Temperature Programmed

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.

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Kinetic modeling and laboratory investigation of catalytic toluene methylation to para-xylene

Petroleum Science and Technology ◽

10.1080/10916466.2017.1369111 ◽

2017 ◽

Vol 35 (18) ◽

pp. 1866-1872 ◽

Cited By ~ 8

Author(s):

Mahdi Abdi Khanghah ◽

Reza Mosayebi Behbahani ◽

Touba Hamoule ◽

Alireza Baghban

Keyword(s):

Laboratory Investigation ◽

Kinetic Modeling ◽

Para Xylene ◽

Toluene Methylation

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A Facile Strategy to Prepare Shaped ZSM-5 Catalyst with Enhanced para-Xylene Selectivity and Stability for Toluene Methylation

10.20944/preprints201704.0009.v1 ◽

2017 ◽

Author(s):

Yiren Wang ◽

Yang Chang ◽

Min Liu ◽

Anfeng Zhang ◽

Chunshan Song ◽

...

Keyword(s):

Physical Adsorption ◽

Catalytic Performance ◽

Acid Sites ◽

The Novel ◽

In Situ Xrd ◽

Para Xylene ◽

Toluene Methylation ◽

Temperature Programmed ◽

Catalytic Performances

This work describes the catalytic performances of attapulgite/ZSM-5 extrudate in comparison to conventional alumina-bound ZSM-5 extrudate in toluene methylation. The novel attapulgite/ZSM-5 extrudate is prepared by using natural clay attapulgite as binder which introduces mobile alkaline species and macropores to the extrudate. In contrast to alumina-bound extrudate, this novel extrudate shows significantly higher para-selectivity and stability. By using characterization techniques, including in-situ XRD, SEM, NH3 temperature programmed desorption (TPD), thermogravimetric analysis and n-hexane/cyclohexane physical adsorption, the catalytic performance improvement of attapulgite/ZSM-5 extrudate is correlated with the neutralization of Brønsted acid sites by mobile alkaline species during calcination and reaction process. Moreover, a higher para-selectivity was obtained over attapulgite-bound modified ZSM-5 extrudate. The strategy of extruding ZSM-5 catalysts with attapulgite as binder is facile and universal. Such method paves a new way for preparation of shaped toluene methylation catalyst with enhanced para-selectivity and stability.

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