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.