Ni–Ce–Al composite oxide catalysts synthesized by solution combustion method: Enhanced catalytic activity for CO methanation

Abstract

Ce-incorporated Ni/γ-Al2O3 catalysts, with Ce loadings from 0wt% to 8wt%, were prepared by solution combustion method (SCM) and evaluated for CO methanation. Compared with Ce-free Ni/γ-Al2O3 catalyst, Ce-doped Ni/γ-Al2O3 catalysts retained higher low- and high-temperature catalytic activity. The Ce-doped Ni/γ-Al2O3 catalyst with Ce content of 6wt% (Ni–6Ce) maintained 100% CO conversion and nearly 100% CH4 selectivity throughout the low-temperature activity test. It is revealed that the promotional effects of Ce species were possibly attributed to the high dispersion and the resultant small sized Ni particles, owing to the formation of Ni–Ce–Al composite oxides. Furthermore, Ce4+/Ce3+ redox couples in Ce-doped catalysts enriched electrons on Ni atoms, facilitating CO dissociation, and thus the conversion. Moreover, Ni–Ce–Al composite oxide catalysts retained better coke-resistant performance at water free condition, leading to higher catalytic activity at high-temperature reaction.