Ruthenium catalyst supported on perovskite-type alkaline earth metal-titanates with strong metal-support interaction for ammonia decomposition

Alkaline earth-metal titanates ATiO 3 (A = Ca, Sr, and Ba) with a perovskite-type structure were used as supports for Ru-based catalysts to produce CO x -free H 2 via NH 3 decomposition. The effects of alkaline-earth metals on the physicochemical characteristics and catalytic activities of Ru/ATiO 3 for NH 3 decomposition were investigated using various techniques. The order of Ru/ATiO 3 for NH 3 conversion is Ru/BaTiO 3 > Ru/SrTiO 3 > Ru/CaTiO 3 > Ru/TiO 2 at the identical conditions, with the Ru/BaTiO 3 catalyst demonstrating the highest NH 3 conversion of 77.8% at 450 °C and a gas hourly space velocity of 30,000 mL/g cat /h, which is 8.7, 2.1, and 1.3 times of that over Ru/TiO 2 , Ru/CaTiO 3 , and Ru/SrTiO 3 , respectively. The formation of the ATiO 3 phase can enrich the concentration of basic sites and oxygen vacancies compared with TiO 2 , which can induce the presence of strong metal-support interaction (SMSI) through the formation of Ru–O–Ti bonds. This SMSI effect increased the dispersion and electron density of Ru nano-particles on ATiO 3 supports, and the electron-rich Ru nano-particles could weaken the chemisorptive strength of N 2 and H 2 on the Ru/ATiO 3 catalysts, thereby promoting the reaction rate for NH 3 decomposition.