TOLUENE DISPROPORTIONATION OVER NIS SIO2-USY HYBRID CATALYSTS - EFFECTS OF SPILT-OVER HYDROGEN/

Toluene disproportionation was studied on hybrid catalysts composed of physically mixed NiS/SiO2 and USY zeolite at 623 K-723 K, 1.0 MPa and W/F=4.6 g h/mol. The activity of the NiS/SiO2-USY hybrid catalyst was two times higher than that of USY in hydrogen atmosphere. Also USY hy brid catalysts containing NiS/Al2O3, NiS/TiO2 and MoS2/Al2O3 showed hi gh activity for toluene disproportionation. The amount of deposited co ke on NiS/SiO2, USY zeolite and NiS/SiO2-USY (USY content 50%) catalys ts was 0.45, 16.1 and 7.6%, respectively, which suggests that coke dep osited only on the zeolite. Although the rate of coke deposition was s carcely affected by the presence of NiS/SiO2, the deactivation rate wa s effectively suppressed by the presence of NiS/SiO2 and gaseous hydro gen. It was suggested that hydrogen species supplied by hydrogen spill over at NiS sites and inter-particle migration promote the turnover fr equency of toluene disproportionation at Bronsted acid sites on USY ze olite surface.