Catalytic activity of spinel oxides MgCr2O4 and CoCr2O4 for methane combustion

The chrome-containing spinels, MgCr2O4 and CoCr2O4, were prepared via sol–gel method using glucose as a complexing agent after calcination at 1400 °C and investigated as catalysts for catalytic combustion of methane. XRD indicated that single phase spinel oxides of MgCr2O4 and CoCr2O4 had formed. XPS analysis exhibited that Cr3+ was present in both catalysts, whereas a small amount of Cr6+ was only detected in MgCr2O4. The spinel MgCr2O4 proved to be very active and its catalytic activity reached T10 = 400 °C and T90 = 684 °C for methane combustion, which was much superior to that of CoCr2O4 (T10 = 480 °C and T90 = 750 °C). Larger surface area (1.1 m2/g), more flexible reactive surface oxygen species, and appropriate surface and bulk structure of MgCr2O4 may contribute to its excellent catalytic activity toward methane combustion.