| dc.description.abstract | Nano-gold catalyst has been reported to have high activity and selectivity for liquid phase hydrogenation reaction. In this study, gold was loaded on different supports. The gold-containing bimetals were loaded on titanium-oxide. The catalyst was then optimize the molar ratio of Pd to Au on TiO2 for p-CNB hydrogenation reaction to have high activity.The monometallic Au catalysts were made by deposition-precipitation method. For bimetallic catalysts, gold and different metal solutions were added by the deposition-precipitation method, using NaBH4 to reduce them. Different metals and different molar ratios of Pd/Au were tested to find the high activity for p-CNB hydrogenation reaction. These catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy(XPS) and temperature programmed reduction (TPR). The catalytic properties of these catalysts were studied for hydrogenation of p-chloronitrobenzene (p-CNB). The conditions for hydrogenation reaction were 1.1 MPa and 0.55 MPa as H2 pressure, 373 K and room temperature as reaction temperature and 300 rpm stirring speed. Methanol was used as the solvent, the concentration of p-CNB was 0.2 M (2.54 g p-CNB in 80 ml methanol) and the amount of gold based catalyst was 0.5g. As results, titanium-oxide had a higher reaction activity than others, and adding palladium into gold base catalysts showed the high activity and selectivity. Comparing with different metals, adding palladium showed obviously a higher activity and selectivity. All of Pd/Au catalysts could reach 100% conversion of p-CNB on the same reaction conditions in short times. The reaction even It also could take place at room temperature and low hydrogen pressure. Only very small amount of palladium could improve the reaction activity and selectivity. According to the characteristics of the catalysts, adding palladium could reduce gold-valence state, increase reaction active sites. Therefore, gold and palladium catalysts could promote conversion and selectivity for hydrogenation reaction. | en_US |