Selective removal of CO from hydrogen-rich stream over CuO/CexSn1−xO2–Al2O3 catalysts

The solid solutions of CexSn1−xO2 incorporated with alumina to form CexSn1−xO2–Al2O3 mixed oxides, by the suspension/co-precipitation method, were used to prepare CuO/CexSn1−xO2–Al2O3 catalysts for the selective oxidation of CO in excess hydrogen. Incorporating Al2O3 increased the dispersion of CexSn1−xO2, but did not change their main structures and did not weaken their redox properties. Doping Sn4+ into CeO2 increased the mobility of lattice oxygen and enhanced the activity of the 7%CuO/CexSn1−xO2–Al2O3 catalyst in the selective oxidation of CO. The selective oxidation of CO was weakened as the doped fraction of Sn4+ exceeded 0.5. Incorporating appropriate amounts of Sn4+ and Al2O3 could obtain good candidates 7%CuO/CexSn1−xO2–Al2O3(20%), 1–x=0.1–0.5, for a preferential oxidation (PROX) unit in a polymer electrolyte membrane fuel cell system for removing CO. Its activity was comparable with, and its selectivity was much larger than, that of the noble catalyst 5%Pt/Al2O3.