Improvement of nano-particulate CexZr1-xO2 composite oxides supported cobalt oxide catalysts for CO preferential oxidation in H2-rich gases

The Co3O4/CexZr1-xO2 is a potential catalyst for CO preferential oxidation (CO PROX) in excess hydrogen. This study is devoted to the optimization of the nano-particulate CeO2-ZrO2 supported cobalt oxide catalysts. The effects of Ce/(Ce + Zr) atomic ratio, Co3O4 loading, calcination temperature, as well as reaction conditions like addition of CO2 and H2O, gas hourly space velocity (GHSV) and O-2 concentration on the catalytic properties were investigated. Moreover, the temperature programmed reduction (TPR) and the powder X-ray diffraction (XRD) techniques were used to reveal the relationship between catalyst nature and catalytic properties. Results demonstrate that the catalytic performance of Co3O4/CexZr1-xO2 catalysts is strongly dependent on the H-2 uptake, reduction temperature and crystallite size affected by Ce/(Ce + Zr) atomic ratio, cobalt oxide loading and calcination temperature. It is also found that the developed catalyst possesses high catalytic stability, and no obvious decrease in either CO conversion or CO2 selectivity can be observed even with the existence of CO2 and H2O in the feed. 16 wt.% Co3O4/Ce0.85Zr0.15O2 calcined at 450 degrees C could be a promising catalyst for the CO PROX reaction to eliminate trace CO from H-2-rich gas.