IrFeOx/SiO2—A highly active catalyst for preferential CO oxidation in H2

A novel bifunctional catalyst IrFeOx/SiO2, which was very active and selective for preferential oxidation of CO under H2-rich atmosphere, was developed in this study. XRD, H2-TPR, and chemisorption were applied to characterize three kinds of IrFeOx/SiO2 catalysts prepared by different impregnation sequences. The results indicated that both FeOx and Ir species were highly dispersed on the SiO2 support; the reduction of Ir species in the Fe-promoted Ir/SiO2 catalyst became easier than those in the Ir/SiO2, together with the partial reduction of Fe2O3; the saturation uptake of O2 adsorption was greatly enhanced. In-situ DRIFTS, XPS, and Mössbauer techniques were further applied to detect the structural information on the selected Ir-FeOx/SiO2 catalyst prepared by co-impregnation method. A non-competitive adsorption catalytic mechanism was proposed where CO adsorbed on Ir sites and O2 adsorbed on FeOx sites; the reaction probably took place at the interface of Ir and FeOx or via a spill-over process.