Transition metal and Pr co-doping induced oxygen vacancy in Pd/CeO2 catalyst boosts low-temperature CO oxidation

Abstract

Cerium oxide-based materials have wide application prospects in catalytic oxidation reactions. Doping valence metals in CeO2 is an effective strategy to increase the content of oxygen vacancy of CeO2 and regulate the surface and interface structure of CeO2 supported metal catalysts. In this work, transition metal (M = Fe, Co and Mn) and Pr co-doped CeO2 nanorod were prepared by hydrothermal method and used to support Pd, which significantly improved the activity of CO catalytic oxidation. Under dry and wet condition, the T99 (temperature to achieve 99% conversion of CO) decreased from 190 °C and 165 °C for single-doped Pd/Pr-CeO2 catalyst (Pd content of 0.2 wt%) to 125 °C and 107 °C for co-doped Pd/FePr-CeO2 catalyst under reaction condition with GHSV (gas hourly space velocity) of 70, 000 mL gcat.-1h−1, respectively. Moreover, the Pd/FePr-CeO2 catalyst showed an excellent stability and kept its activity more than 2400 min. The systematic characterizations revealed that the outstanding CO catalytic performance is attributed to the co-doping of Pr and Fe, which increases the oxygen vacancy content on the catalyst surface, promotes the activation of lattice oxygen in the support, and strengthens the interaction and electron transport ability between Pd and the support. This work opens promising perspectives to enhance the activity of supported metal catalysts in oxidation reactions by co-doping of valence metals in oxide supports.