CO preferential oxidation (CO-PROX)

CO preferential oxidation (CO-PROX) has so far been a reliable technique as a fine purification step of the feed gas downstream the WGS unit [2,6–10]. In order to achieve the required low CO concentration permanently, a two-step system is usually needed [4]. In addition, this process requires an additional, closely controlled, low rate O2 supply to keep the unwanted oxidation of hydrogen as low as possible [2,10].Selective CO methanation is considered an attractive alternative to preferential CO oxidation for the removal of CO from H2 rich gases for PEMFC applications [11,12]. Here, no additional reactant is needed such as air for CO-PROX, but the risk of undesired CO2 methanation, which also consumes additional H2, is likely to occur.