Highly Active and Stable Bimetallic Nickel-Copper Core-Ceria Shell Catalyst for High-Temperature Water-Gas Shift Reaction

Highly dispersed bimetallic Ni-Cu core encapsulated by a CeO2 shell catalyst has been synthesized by a combination of positive emulsion and the self-assembly method. Several catalyst characterization techniques were implemented to investigate the core-shell structure and its unique properties. Field-emission TEM, X-ray diffraction, X-ray photoelectron spectroscopy, and N2O chemisorption analyses showed that uniform bimetallic Ni-Cu particles with an average size of 3.4nm and narrow size distribution encapsulated by CeO2 shell with an average size of 4.3-5.4nm were formed. 10wt% bimetallic Ni-Cu catalyst encapsulated by CeO2 exhibited high catalytic activity and stability at 500 degrees C in the high-temperature water-gas shift reaction. This could owe to the contributing factors of a high level of metal-support interaction, small bimetallic Ni-Cu particle size, and high surface lattice oxygen concentration enhancing the water-gas shift reaction. Moreover, strongly adsorbed CO and the presence of typeI OH on the core-shell catalyst implied that these two active species could be the most important species in the formation of active intermediate species for the water-gas shift reaction, as evidenced by CO temperature-programmed reduction-MS and insitu diffuse-reflectance IR Fourier transform spectroscopy.