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An in situ methylation of toluene using syngas over bifunctional mixture of Cr2O3/ZnO and HZSM-5

Paper ID Volume ID Publish Year Pages File Format Full-Text
40294 45849 2013 8 PDF Available
Title
An in situ methylation of toluene using syngas over bifunctional mixture of Cr2O3/ZnO and HZSM-5
Abstract

•Cr2O3/ZnO catalyst mixed with HZSM-5 were tested for toluene methylation using syngas.•Catalytic synergy of bifunctional catalyst (Cr2O3/ZnO + HZSM-5) was evaluated.•Bifunctional catalyst exhibited much higher activity than monofunctional ones.•Catalytic synergy was manifested with (Cr2O3/ZnO)/HZSM-5 weight ratio of 1/1.

The in situ methylation of toluene using syngas (in situ methylation hereafter) was studied to produce xylenes over bifunctional catalysts comprising Cr2O3/ZnO (CrZ) and HZSM-5 (SiO2/Al2O3 = 30) in a fixed-bed down-flow reactor at 460 psig. In this study, three basic aspects in the in situ methylation were investigated: (1) the catalytic activity of CrZ as the methanol synthesis catalyst with respect to the equilibrium conversion, (2) the evaluation of catalytic synergies in the in situ methylation over bifunctional catalyst, and (3) the effect of the ratio of catalytic functions regarding the ratio of methanol synthesis catalyst to HZSM-5, and their intimacy. The CrZ catalyst exhibited very low CO conversion to methanol in the methanol synthesis reaction, which is controlled by the equilibrium. However, the bifunctional mixture of CrZ and HZSM-5 catalysts exhibited significant catalytic synergies in the in situ methylation in terms of catalytic activity and product selectivities, with about a 10-times-higher CO conversion rate, and 2- to 3-times-higher toluene conversion and xylene production rates compared to the monofunctional catalysis of methanol synthesis and toluene disproportionation, respectively. The in situ methylation also gave rise to higher catalytic performance than in typical toluene methylation conducted with a molar feed ratio of methanol/toluene of 0.5. The catalytic synergy was manifested when both metallic and acidic functions were brought into close intimacy with a weight ratio of CrZ/HZSM-5 close to one in the in situ methylation.

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Keywords
Syngas; Toluene methylation; Methanol synthesis catalyst; Cr2O3/ZnO; HZSM-5; Bifunctional catalyst; Xylenes production
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An in situ methylation of toluene using syngas over bifunctional mixture of Cr2O3/ZnO and HZSM-5
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 466, 10 September 2013, Pages 90–97
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us