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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/7076

Title: The influence of aluminium sources on the acidic behaviour as well as on the catalytic activity of mesoporous H-AlMCM-41 molecular sieves
Authors: SAKTHIVEL, A
DAPURKAR, SE
GUPTA, NM
KULSHRESHTHA, SK
SELVAM, P
Keywords: tertiary butylation
aromatic-hydrocarbons
t-butylation
mcm-41
phenol
zeolites
alkylation
al-mcm-41
stability
strength
Issue Date: 2003
Publisher: ELSEVIER SCIENCE BV
Citation: MICROPOROUS AND MESOPOROUS MATERIALS, 65(2-3), 177-187
Abstract: A series of mesoporous molecular sieves (AIMCM-41) were synthesized with varying silicon-to-aluminium ratios and using three different aluminium sources, viz., sodium aluminate, aluminium isopropoxide and aluminium. sulphate. The samples were characterized systematically using XRD, TG-DTA, BET surface area, and ICP-AES. In addition, the extent of framework substitution as well as the nature of acid sites was deduced employing Al-27 MAS-NMR, pyridine FT-IR, and NH3-TPD methods. These studies indicate that in case of samples prepared with sodium aluminate, most of the aluminium existed in tetrahedral positions even after calcination. Also, such samples posses moderate-to-strong (Bronsted) acid sites along with small amounts of structural as well as non-framework Lewis acid sites. The density of non-framework acid sites depended upon the source of aluminium following a trend in the order of sodium aluminate < aluminium sulphate < aluminium isopropoxide. Among the various catalysts investigated, those having a silicon-to-aluminium ratio of around 60 irrespective of aluminum sources exhibited highest conversion and good selectivity for vapour phase tertiary-butylation of phenol. This characteristic is attributed to the presence of larger number of moderate-to-strong acid sites and a smaller number of Lewis acid sites. (C) 2003
URI: http://dx.doi.org/10.1016/j.micromeso.2003.08.004
http://dspace.library.iitb.ac.in/xmlui/handle/10054/7076
http://hdl.handle.net/10054/7076
ISSN: 1387-1811
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