Catalytic Investigation of Aluminum Effects on Benzene Hydrogenation Selectivity over Nickel Supported HMS/HZSM-5 Composites

Ni/Al-HMS/HZSM-5 catalysts with varying amounts of Si/Al ratios were prepared via the impregnation method and evaluated for the hydrogenation of benzene at 130−190 °C. To study the catalyst characterization, various methods were used as X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, temperature-programmed desorption of ammonia, H2 chemisorption, N2 adsorption-desorption, and thermogravimetric analysis. The effect of reaction temperature and residence time on catalytic performance was considered and kinetic of this reaction was investigated under different pressures. The results demonstrated that the composite catalysts have high benzene conversion (~80%), medium to low toluene and xylene conversion (16–80%), moderate benzene selectivity (~50%) in the mild reaction condition, and good catalytic stability against the coke deposition.