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Tailoring the properties of hierarchical TS-1 zeolite synthesized from silanized protozeolitic units

Paper ID Volume ID Publish Year Pages File Format Full-Text
40814 45867 2012 11 PDF Available
Title
Tailoring the properties of hierarchical TS-1 zeolite synthesized from silanized protozeolitic units
Abstract

Hierarchical TS-1 zeolites, characterized by having a secondary porosity within supermicro-mesopore range, have been synthesized by silanization of protozeolitic units, previously generated by means of a precrystallization step. The silanization agent anchors over protozeolitic units surface, acting as crystal growth inhibitor during the hydrothermal crystallization treatment and hindering partially the protozeolitic units growth and aggregation. The secondary porosity arises from the voids existing between these protozeolitics units. Both the duration of the precrystallization step and the proportion of the organosilane compound added to the synthesis gel have a significant influence on the physicochemical and textural properties of the resultant materials. Thus, a precrystallization time comprised between 22 and 24 h leads to the highest enhancement of the textural properties. On the other hand, by controlling the organosilane compound proportion added to the synthesis gel, the relative contribution of the secondary porosity can be tailored. The catalytic activity of these materials was evaluated in olefin epoxidation reactions, using tert-butylhydroperoxide (TBHP) as oxidant. The olefin conversion and TOF values reached by hierarchical TS-1 zeolites are remarkably superior to those obtained with the conventional microporous TS-1 zeolite, the best catalytic results being achieved using a 8% mol of silanization agent. Likewise, these zeolites exhibit a high oxidant efficiency and total selectivity to epoxide, parameters which are not affected by the presence of the secondary porosity.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (189 K)Download as PowerPoint slideHighlights► Hierarchical TS-1 has been synthesized by crystallization of silanized protozeolitic units. ► The influence of both precrystallization time and the silanization agent proportion has been explored. ► Physicochemical and catalytic properties of hierarchical TS-1 can be tailored. ► Enhanced secondary porosity leads to a better epoxidation catalytic activity with TBHP.

Keywords
TS-1 zeolite; Hierarchical porosity; Silanization; Epoxidation
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Tailoring the properties of hierarchical TS-1 zeolite synthesized from silanized protozeolitic units
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 435–436, 5 September 2012, Pages 32–42
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