Study On Nickel-based Catalysts For Selective Hydrogenation

Preparation of Ni-based catalysts supported on Al2O3 was studied. Optimize reactive conditions such as temperature, pressure, hydrogen-oil ratio, calcinations temperature and content of nickel were determined by activity, selectivity and stability of catalysts.Effects of promoter on activity, selectivity and sulfur tolerance of catalyst were investigated. The kinds of the promoters were magnesium, copper, potassium, molybdenum, iron, lanthanum cerium and cobalt. The impregnation method was investigated firstly. There were two methods that were co-impregnation and consecutive impregnation. The experimental results validated that the co-impregnation method was better than the other one. Furthermore, the effect of loading on the catalyst performance was studied. Compared to the Cu additive, other additives showed improved catalytic activity, but decreased selectivity. In all the seven additives, Fe and Co could improve the catalytic activity most, while selectivity declined most, Cu additive improved the selectivity greatly. The sulfur tolerance of the additive catalysts were compared, Ce additive was superior to other additives. By H2-TPR, BET, XRD and other characterization, the mechanism of changes on the performance were analyzed. Catalyst added Ce was optimized as the best on comprehensive performance.Since the addition of Cu additive improved the selectivity of the catalyst greatly, while reduced the catalyst activity, Cu was added in to a single cerium catalyst which was optimized as the best in activity and sulfur tolerance. In order to improve selectivity and keep activity, Ce and Cu dual auxiliary catalyst was prepared. Through the evaluation it was found that the double auxiliary catalyst was better than the single non-additive nickel catalyst and a single auxiliary catalyst in selectivity and sulfur tolerance.