Selective Hydrogenation of Nitrobenzene to Aniline over Ru/SBA-15 Catalysts

A series of Ru/SBA-15 catalysts (0.5-6.0 wt%) are prepared by impregnation method. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), CO-chemisorption, surface area and pore-size distribution measurements. The catalytic activities were evaluated for the vapor phase hydrogenation of nitrobenzene. The dispersion measured by CO-uptake values suggests decrease in dispersion with increasing Ru loading on SBA-15. These findings are well supported by the crystallite size measured from XRD and TEM measurements. XPS study reveals the formation of Ru0 after reduction at 573 K for 3 h. The catalysts exhibit high conversion/selectivity at 4.5 wt% Ru loading during hydrogenation reaction. The particle size measured from CO-chemisorption and TEM analysis related to the TOF during the hydrogenation reaction. Ru/SBA-15 catalysts are found to show higher conversion/selectivities during hydrogenation of nitrobenzene than Ru/SiO2 and Ru/Al2O3 catalysts.