Stability of Co–Ce–Mn mixed-oxide catalysts for CO preferential oxidation in H2-rich gases

The stability of Co–Ce–Mn mixed-oxide catalysts for CO preferential oxidation in H2-rich gases was investigated. The deactivation mechanism was explored using Fourier-transform infrared spectroscopy (FTIR), temperature-programmed desorption (TPD), and reduction and oxidation techniques. The deactivation of the catalysts was observed in reaction gas streams containing CO2. FTIR and CO2-TPD revealed carbonate formation in the deactivated samples. The activity of the deactivated catalysts could be partially regenerated by CO2 desorption and fully regenerated by oxidation treatment which led to a change in the oxidation state of cobalt ions. It is proposed that both carbonate accumulation and the change in the oxidation state of cobalt ions during CO preferential oxidation are responsible for the deactivation of Co–Ce–Mn catalysts.