Transalkylation and disproportionation of toluene and C9 aromatics over zeolite beta

Transalkylation and disproportionation (TADP) of toluene and C₉ aromatics from a commercial stream have been studied over a zeolite possessing a three-dimensional, 12-membered ring pore system. The study encompassed the effect of C₉ aromatics content in feed on TADP. Formation of xylenes was maximum with a feed containing 50 50 toluene and C₉ aromatics. In order to understand the role of different C₉ aromatics in TADP, experiments using individual C₉ aromatics with and without toluene mixture as feed were carried out. An interesting observation of these experiments was that ethyltoluenes produced xylenes through disproportionation of toluene generated from their deethylation. The total yield of xylenes was much less than that obtained from trimethyl benzenes. A reaction scheme accounting all the reactions taking place during TADP is proposed.