Templated Synthesis of Copper Modified Tin-Doped Ceria for Catalytic CO Oxidation

Abstract

Ceria-tin (CS) oxide catalytic systems were synthesized using cetyltrimethylammonium bromide (CTAB) and Pluronic 123 (P123) templates and modified with CuOx using two techniques: the “one-pot” method (Cu addition during CS synthesis) and the post-impregnation (IM). The catalysts were tested in CO oxidation in the stoichiometric CO/O2 mixture balanced with He. XRD, TPR, Raman spectroscopy, XPS, N2 physisorption, H2-TPR, HR TEM and SEM–EDS were used for catalysts characterization. CS P123 showed better CO conversion than CS CTAB at 100–200 °C and lower at higher temperatures, due to higher defectiveness and oxygen mobility in CS CTAB. Modification with copper improves catalytic action of all catalysts at low temperatures, but to a different degree depending on modification technique and template type. Cu–CS CTAB prepared by the “one-pot” technique was much more efficient than its IM counterpart and both P123-templated catalysts. The best efficiency of Cu–CS CTAB results from the strongest interaction of Cu with CS to form CuCeSnOx which provides accessibility of Cu+ adsorption sites, and low stability of surface carbonate groups improving low-temperature efficiency. Cu–CS P123 IM efficiency decreases in the oxygen-enriched reaction mixture, the reasons are discussed in terms of the ratio between oxidation and reduction stage rates in MvK mechanism.