SiO2/Ni and CeO2/Ni catalysts for single-stage water gas shift reaction

SiO2- and CeO2-promoted Ni catalysts, as an alternative to traditional water gas shift (WGS) catalysts, were studied through various characterization methods. CO removal was enhanced by CeO2 promotion on Ni, but CeO2 affected methanation rather than the WGS reaction. Mobile surface oxygen, a typical property of CeO2, affected the Ni surface properties and weakened the bond strength between C and O atoms of carbon monoxide. On the contrary, in the case of SiO2-promoted Ni catalyst, the SiO2 supplied a hydroxyl group (–OH) to the Ni catalyst resulting in greater selectivity toward the WGS reaction than to methanation. Selectivity to the WGS reaction on the CeO2-promoted Ni catalyst was lower than that on Ni bulk catalyst, while the SiO2-promoted Ni catalyst showed higher selectivity to WGS than both the Ni bulk and CeO2-promoted Ni catalysts.