Comparison of the effects of the catalyst preparation method and CeO2 morphology on the catalytic activity of Pt/CeO2 catalysts for the water-gas shift reaction

Abstract

In this study, the effects of the catalyst preparation method and CeO₂ particle morphology of Pt/CeO₂ catalysts for the water-gas shift reaction are compared. CeO₂ supports having nanorod and nanocube morphologies were prepared. Over both types of supports, 1 wt% Pt was loaded via either the incipient wetness impregnation (IWI) method or the strong electrostatic adsorption (SEA) method. In total, four types of Pt/CeO₂ catalysts were prepared, and these were characterized using various techniques and tested for the water-gas shift reaction. The cube-shaped-CeO₂-based catalysts showed higher catalytic activities than the rod-shaped-CeO₂-based catalysts due to the higher dispersion of Pt⁰ regardless of the catalyst preparation method. From the viewpoint of the catalyst preparation method, the IWI-prepared catalysts showed higher catalytic activity than the SEA-prepared catalysts regardless of the morphology of CeO₂ because of the larger amount of oxygen vacancies induced by the strong interaction between PtO_x and CeO₂. These results highlight the fact that the catalyst preparation method and the morphology of the CeO₂ support strongly affect the key factors (Pt⁰ dispersion and number of oxygen vacancies) separately, which are directly related to the catalytic activity in the water-gas shift reaction. It also confirms that both key factors should achieve high values to attain high catalytic activity.