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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/6765

Title: Mesoporous H-AlMCM-48: highly efficient solid acid catalyst
Authors: DAPURKAR, SE
SELVAM, P
Keywords: friedel-crafts alkylation
molecular-sieve mcm-48
x-ray-diffraction
aromatic-hydrocarbons
tertiary butylation
fine chemicals
t-butylation
phenol
aluminosilicate
zeolites
Issue Date: 2003
Publisher: ELSEVIER SCIENCE BV
Citation: APPLIED CATALYSIS A-GENERAL, 254(2), 239-249
Abstract: Mesoporous cubic Na-AlMCM-48 molecular sieve catalyst with a Si/Al (molar) ratio of 60 was synthesized hydrothermally and characterized by various analytical and spectroscopic techniques. Al-27 MAS-NNIR results indicate that the presence of aluminum in tetrahedral framework (Bronsted acid site) in both as-synthesized and calcined samples. However, in the case of the latter, a small amount of aluminum was found to be in octahedral coordination. This observation is well supported by NH3-TPD studies over protonated catalyst (H-AlMCM-48), where desorption profile at higher temperature shows features characteristic of Lewis acid sites. Further, these studies also indicate that the presence of high concentration of moderate-to-strong Bronsted acid sites at lower temperature, which are more suitable for the para-selective tertiary-butylation reaction of phenol. Hence, in the present investigation, the reaction was carried out H-AIMCM-48, which however showed much higher activity as compared to the hexagonal H-AlMCM-41. In addition, it was also found that the former does not get deactivated owing to three-dimensional pore system while the latter is susceptible to deactivation on account of one-dimensional pore system. (C) 2003
URI: http://dx.doi.org/10.1016/S0926-860X(03)00486-1
http://dspace.library.iitb.ac.in/xmlui/handle/10054/6765
http://hdl.handle.net/10054/6765
ISSN: 0926-860X
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