Ordered mesoporous Cu-Mn-Ce ternary metal oxide catalysts for low temperature water-gas shift reaction

Abstract

Highly ordered mesoporous Cu-Mn-Ce ternary metal oxide materials with various Cu/Mn molar ratios were successfully synthesized by using a nano-casting method from a mesoporous silica template with a cubic Ia3d mesostructure. The ternary metal oxide materials were characterized by X-ray diffraction (XRD), N2-sorption, electron microscopy, Raman spectroscopy, H2-temperature programmed reduction and CO-temperature programmed desorption. The XRD results indicated that the materials did not show any diffraction peaks corresponding to copper and manganese oxides, ensuring the formation of CuxMn0.2-xCe0.8O2 (x=0–0.2). The WGS activity of the ternary metal oxide catalysts increased as the molar ratios of Cu/Mn increased. Among the catalysts, the mesoporous Cu0.18Mn0.02Ce0.8O2 catalyst exhibited the best catalytic activity in low temperature range with zero methane yield. Moreover, this catalyst showed excellent catalytic stability during the reaction. The observed enhancement in the WGS performances were attributed to high surface area, uniform crystalline framework with increased structural defect, highly dispersed copper and manganese within the ceria lattice or on the surface, and strong metal support interaction.