Promoting effects of pretreatment on Pd/CeO_2 catalysts for CO oxidation

摘要

c CeO2 supported Pd catalysts were prepared in which the Pd species were presented in form of PdO and Ce1-xPdxO2-delta solid solution. The Pd/CeO2 catalysts were thermal treated for varying duration and its effect on Pd species was explored. The transformation of Pd species and redispersion were observed under oxidizing conditions at 500 degrees C. For catalyst treated with 10 h, more Pd ions penetrated into the CeO2 matrix to form Ce1-xPdxO2-delta solid solution, resulting in a 90% CO conversion at 84 degrees C after H-2 reduction. Another thermal treatment time extension led to an extraction of Pd from CeO2 lattice in tandem with higher dispersion and smaller PdO particles on the surface, which was demonstrated by the results of XRD, ICP, TEM images, CO pulse adsorption and CO-TPR as a redispersion phenomenon. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.