The role of iron oxide in the highly effective Fe-modified Co3O4 catalyst for low-temperature CO oxidation

A series of iron modified cobalt oxide catalysts (FeaCobOx (b : a = MCo : MFe, 10 < x < 15)) were prepared by a co-precipitation method, characterized by nitrogen adsorption–desorption, XRD, Raman spectroscopy, XPS, H2-temperature programmed reduction, CO-temperature-programmed desorption, O2-temperature-programmed desorption and time-resolved CO titration, and their catalytic activities for CO oxidation were evaluated. When Co : Fe is 8 : 2 (mol), the Fe2Co8Ox catalyst exhibits a very high catalytic activity, in which CO can be completely converted to CO2 at −80 °C. The results show that the addition of Fe to Co3O4 can increase its surface area and inhibit the agglomeration of iron oxide, improve the reduction behaviour of Co3O4, optimize the ratio of Co3+ : Co2+ on the catalyst surface, and promote CO adsorption and CO2 desorption on the catalyst surface. The oxygen species on Fe2Co8Ox are more active than those on Co3O4, and when the feed gas is lacking in oxygen the lattice oxygen of Fe2Co8Ox can easily overflow to the surface to participate in the oxidation of CO.