Catalysis Today, Vol.363, 105-110, 2021
Inverse CeO2/CuO WGS catalysts: Influence of the presence of oxygen in the reactant mixture
Three catalysts based on inverse configuration of copper-ceria catalysts, i.e. CeO2/CuO and two others in which the copper oxide phase is doped with Mn and Zn, respectively, are examined with respect to their performance for the water-gas shift reaction (WGS) and the influence of oxygen and/or hydrogen presence in the reaction mixture. Multitechnique characterization of the catalysts evidence the inverse configuration of the catalysts prepared by microemulsion method, which are basically constituted by small ceria particles of 4-5 nm supported onto larger copper oxide particles of 12-20 nm. Doping with Mn or Zn enhances the WGS performance of the catalyst. The presence of small amounts of oxygen in the reaction mixture importantly enhances the CO conversion as a consequence of the competing CO oxidation reaction. However, oxygen promotion of the WGS activity is only observed for the undoped catalyst at relatively low temperature and high CO/O-2 ratio. The catalysts display high CO conversion levels even in the presence of hydrogen and oxygen, suggesting the feasibility of carrying out WGS and CO-PROX in a single step using them.