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Direct synthesis of well-ordered mesoporous Al-SBA-15 and its correlation with the catalytic activity

Paper ID Volume ID Publish Year Pages File Format Full-Text
41340 45885 2011 9 PDF Available
Title
Direct synthesis of well-ordered mesoporous Al-SBA-15 and its correlation with the catalytic activity
Abstract

The synthesis of Al-SBA-15 under milder acidic conditions were made through an adjusting the molar H2O/HCl ratio which indicate the formation of Si–O–Al linkages that lead to isomorphous substitution of Si4+ by some Al3+ ions. By adjusting the H2O/HCl molar ratio, Al gets incorporated into the lattice of SBA-15, which is evidenced by XRD, N2 adsorption, TEM, 29Si and 27Al MAS NMR spectroscopic data. Aluminium incorporated SBA-15 samples retained both structural and textural properties of SBA-15. The 27Al MAS NMR confirms that a large proportion of the Al is inserted into tetrahedral positions within the framework. The Al3+ ions could assume a tetrahedral coordination and be part of the hexagonal structure of silica in Al-SBA-15. In the present study, we have examined the effectiveness of Al-SBA-15, as an acid catalyst for the esterification of acetic acid and in benzylation of anisole. The high activity of Al-20 sample in esterification reaction has been attributed to isolated, generally tetrahedrally coordinated, framework Al species. While in benzylation of anisole, the best result was achieved with Al-5 catalyst. The selectivity for benzylanisole increases and that for dibenzylether decreases with increase in the Si/Al ratio of Al-SBA-15.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (124 K)Download as PowerPoint slideHighlights► Al-SBA-15 samples with different Si/Al ratio were prepared by direct synthesis method. ► Catalytic activities for esterification of acetic acid and benzylation of anisole. ► Effects of Al-doping on the structure of the SBA-15 and on the catalytic performance.

Keywords
Al-SBA-15; Esterification of acetic acid; Benzylation of anisole
First Page Preview
Direct synthesis of well-ordered mesoporous Al-SBA-15 and its correlation with the catalytic activity
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 400, Issues 1–2, 30 June 2011, Pages 176–184
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis