Comparative study of CeO_2/CuO and CuO/CeO_2 catalysts on catalytic performance for preferential CO oxidation

摘要

The CeO_2/CuO and CuO/CeO_2 catalysts were synthesized by the hydrothermal method and characterized via XRD, SEM, H_2-TPR, HRTEM, XPS and N_2 adsorption-desorption techniques. The study shows that the rod-like structure is self-assembled CeO_2, and both hydrothermal time and Ce/Cu molar ratio are important factors when the particle-like CeO_2 is being self-assembled into the rod-like CeO_2. The CuO is key active component in the CO-PROX reaction, and its reduction has a negative influence on the selective oxidation of CO. The advantage of the inverse CeO_2/CuO catalyst is that it still can provide sufficient CuO for CO oxidation before 200 ℃ in the hydrogen-rich reductive gasses. The traditional CuO/CeO_2 catalyst shows better activity at lower temperature and the inverse CeO_2/CuO catalysts present higher CO_2 selectivity when the CO conversion reaches 100%. The performance of mixed sample verifies that they might be complementary in the CO-PROX system.