Synthesis characterisation and Catalytic performance of Fe3 Ga3 and Al3 incorporated mesoporous molecular sieves

Abstract

The industrial usage of homogeneous acids such as AlCl3, BF3, FeCl3, TiCl4 and protonic acids viz., HCl, H2SO4, HNO3, etc. as catalysts for producing fine and specialty chemicals have unleashed irreversible damage to the environment through pollution and waste. In the present investigation, heteroatom incorporated mesoporous SBA-1, SBA-15 and KIT-5 materials were synthesised hydrothermally using cetyltriethylammonium bromide, tri-block copolymer Pluronic P123 (molecular weight=5800, EO20PO70EO20) and Pluronic F127 (molecular weight=12,500, EO97PO69EO97) as structure directing agents respectively. The introduction of transition metal ions such as Fe3+ and Ga3+ in SBA-1 and Al3+ in SBA-1, SBA-15 and KIT-5 mesoporous materials were achieved in highly acidic medium. The influence of temperature, feed ratio and time on stream was examined for all reactions in order to optimize suitable reaction conditions to achieve maximum conversion and product selectivity. The catalytic activity of all the samples was also compared with zeolites and other mesoporous materials. The reaction kinetics has been investigated in detail and the results are clearly discussed in relevance with the physico-chemical characterisation data. Among Al-SBA-1 catalysts with different nSi/nAl ratios, Al-SBA-1(39) is found to be highly active, showing high acetic anhydride conversion with a clean selectivity to 3, 4-dimethoxyacetophenone (3, 4-DMAP). The activity of Al-SBA-15 catalysts in the acylation of veratrole was found to increase with increasing nSi/nAl ratio from 7 to 45 and then decreases for nSi/nAl ratio of 136. The three-dimensional cage type mesoporous Al-KIT-5 catalysts have been tested for the acylation of veratrole and other aromatic substrates such as anisole, isobutylbenzene and 2-methoxynapthalene with acetic anhydride as the acylating agent under liquid phase condition. It is found that Al-KIT-5(10) showed remarkable catalytic performance in the acylation of veratrole over zeolites and other mesoporous catalysts newline