Effect of the Modifier on the Catalytic Properties and Thermal Stability of Ru–Cs(Ba)/Sibunit Catalyst for Ammonia Decomposition

Abstract

Based on the Sibunit carbon composite, Ru–Cs(Ba)/Sibunit catalysts with Cs(Ba) : Ru molar ratios of 0.5, 1.5, and 2.5 were obtained. The catalytic activity of the obtained promoted catalysts in the decomposition of ammonia and their thermal resistance to methanation are compared. In the reaction of ammonia decomposition, the specific activity (W_sp) of barium-containing catalysts proved to be 2 times lower than the specific activity of cesium-containing samples with the same molar M : Ru ratio. Thus, W_sp at 500°С was 29.4 mmol H₂ min^–1 for 0.5Cs–Ru/Sibunit and 15.4 mmol H₂ g^–1_cat min^–1 for 0.5Ba–Ru/Sibunit. It was shown that the introduction of barium at molar ratios Ba : Ru = of 0.5–2.5 significantly increases the thermal stability of the samples defined as the ratio of the weight of hydrogen obtained on the catalyst to the weight of carbon subjected to methanation. There is 52 g H₂ for nonpromoted Ru/Sibunit catalyst, 370 g H₂ for the 0.5Ba–Ru/Sibunit sample, 200 g H₂ for the 1.5Ba–Ru/Sibunit sample, and 150 g H₂ for the 2.5Ba–Ru/Sibunit sample per 1 g of carbon loss.