Effect of pretreatment on the activity of Ni catalyst for CO removal reaction by water–gas shift and methanation

An Ni metal catalyst manufactured by the tapecasting method for use as a structural catalyst did not exhibit catalytic activity for the carbon monoxide (CO) removal reaction. However, the catalyst pretreated by an oxidation and reduction process showed superior activity for CO removal via water–gas shift and methanation, resulting in a decrease of the CO concentration to below 1% in reformate gas. The catalytic activity was generated by the reorganization of the surface structure of Ni metal, and enhanced by surface oxygen intermediates such as Ni(OH)2 and NiOOH promoted by NiO oxidized incompletely after the pretreatment. After the reorganization process induced by the pretreatment, the Ni metal on the surface was converted to active Ni and NiO which played the role of a promoter.