Transalkylation of Toluene with Trimethylbenzene on Synthetic Zeolites

Abstract

Transalkylation of toluene with each isomer of trimethylbenzenes on synthetic mordenites and Y type faujasites was studied. Under the optimum reaction conditions, xylene was formed at the yield of about 45mol% by transalkylation of toluene with 1, 3, 5-trimethylbenzene on H-mordenite, CeY and HY catalyst, accompanied with small quantities of disproportionation of each reactant. With the exception of Be having an ionic radius of only 0.3A, multi-valent cation-exchanged mordenites showed no activity for this transalkylation. By the infrared spectra method, it was found that ammonia, which had a very small molecular size, interacted with the acid sites of cation-exchanged mordenites, but, pyridine, which had the same molecular radius as alkylbenzenes, could not interact with these sites. These results suggested that the exchanged cation stuck out of the mordenite channel wall, thus hindering the diffusion of reactants into the channel and to the active sites. Trimethylbenzene isomers were reactive in the order of 1, 2, 4->1, 2, 3->1, 3, 5- on the H-mordenite catalyst. This order had a relationship with the molecular shape of trimethylbenzene isomers.