TRANSALKYLATION OF THE ALKYLAROMATIC HYDROCARBONS IN THE PRESENCE OF ULTRASTABLE Y-ZEOLITES - TRANSALKYLATION OF TOLUENE WITH TRIMETHYLBENZENES

The catalytic properties of Y zeolites, dealuminated by steam stabiliz ation, for the transalkylation of toluene with trimethylbenzene were i nvestigated in a pulse microreactor. Some factors influencing this rea ction were taken into account: the reaction temperature, the degree of dealumination, the nature of acid sites and the deposited coke. The t ransalkylation reaction proceeds with good yields on USY. At bulk sili ca to alumina ratio's around 5, a higher activity is observed for the transalkylation of toluene than for the disproportionation of trimethy lbenzenes. Both HNaY and USY samples were characterized using FTIR and XPS of chemisorbed pyridine. These techniques allowed to detect the p resence of the three kinds of acidic sites: the Bronsted acid sites, t he Na+ cations and the extra framework AlO+ species. The effect of the se three sites on catalytic results are discussed as well as the react ivity of alkylaromatic hydrocarbons in the reaction network and the re action mechanism.