Methane combustion over unsupported iron oxide catalysts

Bulk iron oxide, prepared by precipitation and by the citrates method, has been studied as an alternative catalyst for methane combustion. While hemat ite was the dominant phase in all the samples prepared, significant differe nces were observed regarding the activity and stability of the catalysts, d epending on the preparation method. The catalysts prepared by precipitation presented higher surface areas and lower light-off temperatures. Catalyst deactivation is due to sintering under reaction conditions, and becomes mor e severe if the operating temperature exceeds the calcination temperature u sed in catalyst preparation. The best performance in terms of stability and steady-state conversion was obtained with the catalyst prepared by precipi tation and calcined at 600 degreesC. (C) 2001 Elsevier Science B.V. All rig hts reserved.