Preparation of Ru/AC Ammonia Synthesis Catalyst Reduced with Hydrazine Hydrate
WANG Rong, WEI Kemei *, LIN Jianxin, YU Xiujin, MAO Shulu(National Engineering Research Center of Chemical Fertilizer Catalyst, Fuzhou University, Fuzhou 350002, Fujian, China)
The Ru/active carbon (AC) ammonia synthesis catalyst was prepared by the impregnation method using coconut ( A BET = 1?020 m 2/g) as the support. Firstly, AC was impregnated with RuCl 3 aqueous solution. Then the samples were reduced with hydrogen, hydrazine hydrate solution and hydrazine hydrate vapos, respectively. Subsequently, the three Ru/AC samples were impregnated with aqueous solution of barium nitrate and potassium hydroxide. The Ru content was 6% based on the AC mass and the molar ratio of Ru∶K∶Ba was 1∶3∶0 3 in these catalysts. The catalysts were characterized by XPS, N 2 adsorption and CO pulse chemical adsorption. The results showed that Ru was present in different chemical states in the three catalysts obtained with different reductants. The catalyst activity correlated with their surface area and Ru dispersion. The catalyst that was reduced with hydrazine hydrate solution at pH=10～13 in the range from room temperature to 90 ℃ for 20 min had the highest surface area of 942 m 2/g , Ru dispersion of 17 72% and catalytic activity of 20 36%(volume ratio of NH 3) at low pressure. In this catalyst Ru remained in the metallic state when the sample was exposed to atmosphere.