Catalytic activity of spinel oxides MgCr2O4 and CoCr2O4 for methane combustion

•MgCr2O4 and CoCr2O4 were prepared by glucose sol–gel method.•MgCr2O4 showed superior catalytic activity for methane combustion.•Cr6+ plays an important role in determining superior catalytic activity of MgCr2O4.

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.

Graphical abstractXPS spectra of Cr 2p for MgCr2O4; temperature dependence of CH4 combustion over (a) MgCr2O4 and (b) CoCr2O4.Figure optionsDownload full-size imageDownload as PowerPoint slide