Influence of the surface acidity of ZSM-5 support on the catalytic activity of Rh/ZSM-5 for hydrodearomatization of toluene

Rh/ZSM-5 catalysts with varied SiO2/Al2O3 ratio (24–900) were prepared and characterized by powder X-ray diffraction, N2 adsorption–desorption, temperature-programmed desorption of NH3 and cyclohexanol dehydration model reaction. The hydrodearomatization of toluene was studied at different reaction temperature, reduction temperature, hydrogen partial pressures and in the presence of dibenzothiophene (sulfur compound) in a continuous-down-flow catalytic fixed bed reactor. The hydrodearomatization activity and the sulfur tolerance were observed to be strongly dependent on the acidity of the zeolites particularly upon the proximity between metallic and Brønsted acid sites and the concentration of the Brønsted acid sites.