The oxidation of carbon monoxide on a catalyst with a spinel structure containing Mg ferrite

The oxidation of carbon monoxide on xMgO • yFe2O 3 catalysts was studied over the temperature range 440-660 K. The catalysts contained 5, 40, and 75 at % Fe and the spinel MgFe2O 4 and MgO phases. Complete CO conversion on compact and deposited (on γ-Al2O3) catalysts containing 75 at. % Fe occurred at 650-660 K. The kinetics of interaction of CO with adsorbed oxygen was studied on catalysts with 5 and 40 at % Fe below and above the Curie point (T c = 593 ± 10 K). The differences in the reaction orders with respect to gaseous CO and adsorbed oxygen below and above T c were explained as follows. In the ferromagnetic state of the active MgFe 2O4 phase, oxidation involved adsorbed oxygen localized at oxygen vacancies in the environment of Fe3+ ions, whereas, in the paramagnetic state, superexchange interactions were absent in spinel structure fragments. © Nauka/Interperiodica 2007.