Promotion effect of Nb5+ for Cu/CeO2 water–gas shift reaction catalyst by generating mobile electronic carriers

A series of CuO/CeO2 catalysts doping with Nb2O5 were fabricated by co-precipitation method. It is found that the introduction of Nb5+ will result in the substitution of Ce4+ with Nb5+, thus creating mobile electronic carriers in the as-prepared catalysts. The characterization results correlating with the catalytic activity evaluation disclose that the catalyst added with 1 wt. % Nb2O5 shows the most mobile electronic carries, certain amount of weak, medium basic sites and enhanced reducibility and chemical adsorption of CO, thus the best catalytic activity for water–gas shift reaction. However, excessive Nb2O5 addition prevents the incorporation of Cu2+ into CeO2 lattice and partially covers the surface of CuO and CeO2, resulting in weaken their reducibility and interaction between them, thus leading to inferior catalytic performance.