Effect of Cu additives on the performance of a cobalt substituted ceria (Ce0.90Co0.10O2–δ) catalyst in total and preferential CO oxidation

Abstract

The study reports the modification of the developed Ce0.90Co0.10O2–δ catalyst by incorporating copper ions in order to improve the catalytic activity for total and preferential CO oxidation (TOX and PROX). A series of metal ion substituted ceria catalysts, Ce0.90Co0.10O2–δ and Ce0.90-xCuxCo0.10O2–δ (x=0.01, 0.03 and 0.05) were synthesized in a single step by the urea-assisted solution combustion method. The compositions, textural and structural properties of the catalysts were characterized by XRD, XPS, Raman, H2-TPR and ICP-OES. The insertion of Cu ions in Ce0.90Co0.10O2–δ greatly enhanced the reducibility and improved the activity, with especially the Ce0.85Cu0.05Co0.10O2–δ catalyst showing superior catalytic performance compared to other bimetallic catalysts. Analysis of the reaction profiles and rate calculations suggest that H2 and CO oxidation over Ce0.90Co0.10O2–δ may be occurring on the same active sites, while the two reactions appear to be taking place on independent sites over the Cu-containing catalysts. In addition, the effect of H2O/CO2 in PROX has been studied. The degree of deactivation by H2O and CO2 decreased with increasing the Cu content in the catalysts. The presented catalysts are highly active, selective and stable in TOX and PROX.