Vapour phase reaction of toluene with ethyl acetate over Al-MCM-41 molecular sieves

Al-MCM-41 molecular sieves of Si/Al ratios 25, 50 and 150 were synthesised hydrothermally. The vapour phase reaction of toluene with ethyl acetate was studied over these catalysts at 175, 200, 225, 250, 275 degrees C. The products were p-xylene, ethyl benzene (EB), p-ethyl toluene (p-ET), m-ethyl toluene (m-ET), p-methyl acetophenone (p-MAP), o-methyl acetophenone (o-MAP). Transalkylation of toluene to p-xylene, ethylation of toluene to p-ET and isomerisation of the latter to m-ET were observed as the major reactions with minor acylation of toluene. The transalkylation and isomerisation were found to be strongly influenced by the feed ratio and WHSV, respectively. The study of time-on-stream indicated blocking of particularly strong acid sites by coke, which was suggested advantageous in order to reduce such site dependent transalkylation and isomerisation. (c) 2005 Elsevier B.V. All rights reserved.