A study of Rh-Sm-V/SiO_2 catalysts for the preparation of C_2-oxygenates from syngas

摘要

Rh.Sm- V /SiO_2 catalysts for the preparation of C_2-oxygenates were studied by CO + H_2 reactions under medium pressure, temperature-programmed reduction, adsorption of H_2 and CO, and desorption of adsorbed hydrogen. The addition of Sm and V to the Rh/SiO_2 catalyst obviously promoted the activity and selectivity to C2-oxygenates. The Sm3+ ions on the catalysts can be reduced only with difficulty. These Sm3+ ions play roles of improving the dispersion of rhodium, increasing the uptakes of CO and H_2, and promoting the formation of acetic acid and acetaldehyde. Vanadium ions of lower valence have a good capacity of hydrogen storage, and this can enhance the hydrogenation ability of the catalyst, as well as promoting the formation of ethanol.