In situ FT-IR and TPD-MS study of carbon monoxide oxidation over a CeO2/Co3O4 catalyst

The forming of surface species during the adsorption of carbon monoxide (CO) and CO/O2 on a CeO2/Co3O4 catalyst was investigated by in situ Fourier transform infrared (FT-IR) spectroscopy and temperature programmed desorption-mass spectroscopy (TPD-MS). When CO was adsorbed on the CeO2/Co3O4 catalyst, two types of surface species were distinguishable at room temperature: carbonate and bicarbonate. Surface carbonate was adsorbed on the cerium and cobalt, while the surface bicarbonate absorbed on the CeO2/Co3O4 catalyst at 1611, 1391, 1216 and 830 cm−1. Furthermore, the TPD-MS profiles revealed that the CeO2/Co3O4 catalyst showed a greater amount of CO2 than CO at 373 K. The CO desorption from the CeO2/Co3O4 catalyst with increasing temperature showed that the order of thermal stability was surface bicarbonate < surface carbonate < interface carbonate species. Interestingly, the residual carbonate species could remain on the interface up to 473 K. The results revealed that surface bicarbonate could promote the conversion of CO into CO2 for CO oxidation below 50 K.