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The role of external acid sites of ZSM-5 in deactivation of hybrid CuZnAl/ZSM-5 catalyst for direct dimethyl ether synthesis from syngas

Paper ID Volume ID Publish Year Pages File Format Full-Text
39454 45823 2014 10 PDF Available
Title
The role of external acid sites of ZSM-5 in deactivation of hybrid CuZnAl/ZSM-5 catalyst for direct dimethyl ether synthesis from syngas
Abstract

•Dimethyl ether synthesis from syngas was studied on Cu–ZnO–Al2O3/ZSM-5 catalyst.•The catalyst deactivates due to Cu sintering, oxidation and ion exchange with protons.•Deactivation of external acid sites of ZSM-5 slows down Cu sintering and ion exchange.•It results in the higher stability and DME selectivity of catalyst with silylated ZSM-5.

Direct synthesis of dimethyl ether (DME) from syngas was investigated on a series of hybrid Cu–ZnO–Al2O3/ZSM-5 catalysts prepared by kneading. It was found that the initial performance of the catalysts was a function of both zeolite crystallite sizes and Si/Al ratio. The activity of the hybrid catalysts gradually decreased with time on stream because of simultaneous copper sintering, copper oxidation and ion exchange with zeolite hydroxyl groups. Copper sintering led to the decrease in the number of metal active sites, while ion exchange of Cu2+ ions with the hydroxyl groups of the zeolite resulted in lower concentration of acid sites for methanol dehydration. Copper sintering and ion exchange could be slowed down by selective neutralization of the acid sites on the zeolite outer surface by silylation. Both catalyst stability and dimethyl ether productivity were significantly improved.

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Keywords
DME synthesis; Syngas; Deactivation; Cu–ZnO–Al2O3; Silylation; ZSM-5
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The role of external acid sites of ZSM-5 in deactivation of hybrid CuZnAl/ZSM-5 catalyst for direct dimethyl ether synthesis from syngas
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 486, 22 September 2014, Pages 266–275
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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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