Catalytic combustion of methane over cerium-doped cobalt chromite catalysts

Cerium modified cobalt chromite catalysts were prepared via co-precipitation method and investigated for the catalytic combustion of methane. Characterization studies by X-ray diffraction (XRD), Raman spectroscopy, BET, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction mass spectroscopy (CH4 TPR-MS) and temperature-programmed desorption of oxygen (O2-TPD) were carried out.An improvement of the catalytic activity was observed over cerium-substituted cobalt chromite catalysts with appropriate cerium substitution degrees. The best result has been attained with 5% cerium modified catalyst, for which 5% chromium in CoCr2O4 was substituted by cerium, and the catalytic activity reached 90% of methane conversion at 465 °C. The characterization results indicated that cerium doping could deform the spinel structure and cause redistribution of metal ions with different oxidation states; consequently, they would increase crystal defects and oxygen vacancy concentration, which facilitate oxygen mobility and thus increase the catalytic performance of cerium modified cobalt chromite catalysts.

Substitution of chromium in CoCr2O4 by cerium with appropriate amount can enhance the catalytic activity of cobalt chromite in methane combustion. The best results have been attained with 5% cerium modified catalyst, and the catalytic activity reached 90% of methane conversion at 465 °C.Figure optionsDownload high-quality image (159 K)Download as PowerPoint slideHighlights
► Cerium doping deformed the spinel structure of cobalt chromite catalysts.
► Cerium doping increased crystal defects and oxygen vacancy concentration.
► Cerium doping facilitated oxygen mobility.
► Cerium doping promoted the catalytic performance.