Preferential Oxidation of CO in H₂ Stream over Au/MnO₂−CeO₂ Catalysts

Abstract

A series of nanosized gold supported on CeO2, MnO2, and MnO2−CeO2 composite oxides have been prepared by a deposition−precipitation (DP) method and the effects of Mn/Ce atomic ratio on Au/MnO2−CeO2 catalysts and calcination temperature after loading gold for preferential oxidation of CO (PROX) in H2 stream have been investigated using a fixed-bed continuous-flow reactor at various temperatures. The catalysts were characterized by XRD, nitrogen sorption, TEM, and XPS. XRD analysis confirms the phase purity of CeO2 and MnO2 phases and the fine dispersion of Au on Au/MnO2−CeO2 catalysts. XPS analysis shows the formation of MnO2−CeO2 solid phase with manganese loading on ceria support accompanied by an increase in Ce4+ surface concentration. ICP-AES demonstrates the increase in gold loading with manganese addition by DP method. A synergistic catalytic effect on conversion and selectivity was observed in the case of Au/MnO2−CeO2 catalysts, due to the coexistence of metallic and nonmetallic gold species within nano gold particle and the minor presence of Ce3+ species.