Effect of samarium on methanation resistance of activated carbon supported ruthenium catalyst for ammonia synthesis

The effects of samarium(Sm) on carbon-methanation and catalytic activity of the Ba-Ru-K/AC (active carbon) catalyst for ammonia synthesis were investigated. The addition of samarium improved significantly the activity and stability of the catalyst. The results of temperature-programmed desorption (H2-TPD) and in-situ-TPSR FTIR indicated that samarium impeded the adsorption of hydrogen on the catalyst surface, thus leading to the high catalytic activity and resistance to carbon-methanation. XRD patterns reveal that the promoter samarium was in the form of both samarium oxide and carbonide (Sm2C1−x). The formation of Sm2C1−x was probably due to the interaction of samarium with the unsaturated bond of carbon on the surface of active carbon, and thus hindered the carbon-methanation.