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Influence of the calcination treatment on the catalytic properties of hierarchical ZSM-5

Paper ID Volume ID Publish Year Pages File Format Full-Text
55618 47059 2012 11 PDF Available
Title
Influence of the calcination treatment on the catalytic properties of hierarchical ZSM-5
Abstract

The effect of the calcination conditions on the properties and catalytic performance of hierarchical ZSM-5 zeolite has been investigated using different reactions as catalytic tests: acylation of aromatic substrates and rearrangement of linear and cyclic epoxides. The hierarchical h-ZSM-5 material was prepared by crystallization of silanized protozeolitic units. The removal of the organics present in the as-synthesized ZSM-5 samples has been carried out using two different calcination procedures: (i) directly under air atmosphere; (ii) following a two-step (nitrogen-air) treatment.Clear differences are noticed related to the textural properties of the ZSM-5 samples, since the h-ZSM-5 presents higher BET and external surface area than standard ZSM-5 zeolite. Whereas the calcination method does not affect the properties of the reference ZSM-5 sample, noticeable changes were observed over the hierarchical zeolite. The concentration of Brønsted acid sites decreases by half for one-step air calcination, but only a quarter when using a two-step nitrogen/air calcination, showing that the aluminium present in hierarchical ZSM-5 is very sensitive to the calcination conditions as it may undergo framework extraction and dehydroxylation phenomena. For all the studied reactions, the hierarchical sample, calcined by a two-step treatment, presents higher activity than when using direct air calcination.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (252 K)Download as PowerPoint slideHighlights► Additional porosity in hierarchical ZSM-5 zeolite increases the accessibility to the active sites. ► The acidic properties of hierarchical ZSM-5 are very sensitive to the calcination conditions. ► Two-step nitrogen/air treatment allows a stronger Brønsted acidity and to be preserved, leading to improved catalytic activity.

Keywords
Hierarchical ZSM-5 zeolite; Calcination procedure; Friedel–Crafts acylation; Epoxide rearrangement
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Influence of the calcination treatment on the catalytic properties of hierarchical ZSM-5
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 179, Issue 1, 5 January 2012, Pages 91–101
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