Investigation of catalysts M/CeO2 (M = Pt, Rh, or Pd) for purification of CO2 derived from oxycombustion in the absence or presence of water.

Oxyfuel combustion is a promising technology to produce a CO2-rich flue gas ready suitable for sequestration or valorization. But its storage as well as its further valorization requires to increase the CO2 purification as a small amount of CO and NOx are produced during combustion. Based on the technology developed for three-way converters, similar systems, i.e., M/CeO2 where M is Pt, Pd, or Rh, were studied for NO-CO abatement in a gas stream similar to those obtained when an oxyfuel combustion is performed. The results evidenced that the role of the metal nature influences the performances obtained on NO-CO abatement, platinum supported on ceria being the most efficient catalyst. We also measured the impact of the presence of water in the reaction stream on the catalytic activity of these materials. It appears that the presence of water has a beneficial effect on the different reactions due to a water gas shift reaction that increases the reduction of the NO and favors the formation of N2. The study pointed out that platinum supported on ceria remained the best catalyst, under these wet operating conditions close to industrial ones, for purification of oxyfuel combustion exhausts.