Abstract
The highly dispersed SiO2-supported nickel-based catalysts for CO methanation were prepared by an ethylene glycol (EG) modified wet-impregnation method. The results indicate that the highly dispersed 20Ni/SiO2 (EG) catalyst realized good stability and higher catalytic activity than the catalyst obtained from a non-pretreated silica support (20Ni/SiO2) in CO methanation, due to the smaller nickel particles and strong nickel-silica interaction. By the addition of a small amount of noble metal promoter (Ru, Pt, Pd), the catalytic activity for CO methanation was further improved dramatically and follows the order Ru > Pt > Pd. The added noble metal promoter enhanced the reduction of the nickel oxide by spill-over-hydrogen during reduction treatment, and provided more active species for the methanation reaction, resulting in 7 times higher CO conversion than the non-pretreated 20Ni/SiO2 catalyst. The 20Ni-0.5Ru/SiO2 (EG) catalyst presents superb catalytic performance in CO methanation with high activity (CO conv. 80.2%) as well as high methane selectivity (90.3%) at 275 °C without any deactivation during 50 h reaction. The obtained catalysts were characterized by XRD, TG/DTA, TEM, XPS, TPR, H2 chemisorption, and in situ DRIFTS.