Abstract
The water-gas shift (WGS) performance was investigated over 5%Ni/CeO(2), 5%Ni/Ce(0.95)Pr(0.05)O(1.975), and 1%Re4%Ni/Ce(0.95)Pr(0.05)O(1.975) catalysts to decrease the CO amount and generate extra H(2). CeO(2) and Pr-doped CeO(2) mixed oxides were synthesized using a combustion method. After that, Ni and Re were loaded onto the ceria support via an impregnation method. The structural and redox characteristics of monometallic Ni and bimetallic NiRe materials, which affect their water-gas shift performance, were investigated. The results show that the Pr addition into Ni/ceria increases the specific surface area, decreases the ceria crystallite size, and improves the dispersion of Ni on the CeO(2) surface. Furthermore, Re addition results in the enhancement of the WGS performance of the Ni/Ce(0.95)Pr(0.05)O(1.975) catalyst. Among the studied catalysts, the ReNi/Ce(0.95)Pr(0.05)O(1.975) catalyst showed the highest catalytic activity, reaching 96% of CO conversion at 330°. It was established that the occurrence of more oxygen vacancies accelerates the redox process at the ceria surface. In addition, an increase in the Ni dispersion, Ni surface area, and surface acidity has a positive effect on hydrogen generation during the water-gas shift reaction due to favored CO adsorption.