Surface structure of cobalt, palladium, and mixed oxide‐based catalysts and their activity in methane combustion studied by means of micro‐Raman spectroscopy

Abstract This paper reports the results of the study of surface properties and catalytic activity of cobalt, palladium, and mixed oxide catalysts supported on alumina. Catalytic materials were prepared by the wetness impregnation method directly from solutions of metal salts and using the ultrasound irradiation. The material surface was investigated by micro‐Raman spectroscopy, and the activity in methane combustion was monitored. The results indicated the presence of different metal oxides on the catalysts' surfaces. Cobalt spinel Co 3 O 4 was the main phase of the cobalt catalysts as well as species resulted from interactions with alumina support. In the case of palladium catalysts, the PdO was most prevalent. The article also discusses the observed variation in band position in the Raman spectra and compares the band assignment with literature data. The palladium and mixed oxide catalysts showed average conversion higher than 50% for methane combustion at 673.15 K (400 °C) especially those after sonication.