Highly active three-dimensional cage type mesoporous aluminosilicates and their catalytic performances in the acetylation of aromatics

Three-dimensional cage type mesoporous aluminosilicates (AlKIT-5) with different nSi/nAl ratios have been successfully synthesized hydrothermally using pluronic F127 as a template under highly acidic medium [P. Srinivasu, S. Alam, V.V. Balasubramanian, S. Velmathi, D.P. Sawant, W. Böhlmann, S.P. Mirajkar, K. Ariga, S.B. Halligudi, A. Vinu, Adv. Funct. Mater., in press]. The catalysts have been unambiguously characterized by XRD, N2 adsorption, and TPD of NH3, and utilized for the acetylation of veratrole, and other aromatic substrates such as anisole, isobutylbenzene, and 2-methoxynaphthalene, using acetic anhydride (AA) as an acylating agent under liquid phase conditions. The effect of various parameters such as the reaction temperature, reaction time, reactant mole ratios, and amount of aluminium, on the AA conversion in the acetylation of veratrole has been investigated in detail to discover the optimized reaction condition. The reaction conditions were optimized to get more conversion of acetic anhydride and the activity of these catalysts has been compared with zeolite catalysts namely HY, Hβ, H-mordenite, and HZSM-5 zeolites, and the results are discussed in detail. It has been found that the AlKIT-5 catalysts showed excellent performance in the acetylation of veratrole over zeolites and other mesoporous catalysts studied under the optimized reaction conditions. Among the catalysts studied, AlKIT-5(10) was found to be the best catalyst, showing high conversion of AA and very high selectivity to the desired products. The conversion of AA decreases in the following order: AlKIT-5(10) > AlKIT-5(28) > HY(13.5) > Hβ(30) > AlKIT-5(44) > AlMCM-41(22) > H-mordenite(20) > ZSM-5(60). Moreover, the kinetics of the AlKIT-5(10) catalyst in the acetylation of veratrole has been investigated in detail and the results are clearly discussed.