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

Abstract

The Co₃O₄/Ce_xZr_1−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 O₂ 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/Ce_xZr_1−xO₂ catalysts is strongly dependent on the H₂ 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/Ce_0.85Zr_0.15O₂ calcined at 450 °C could be a promising catalyst for the CO PROX reaction to eliminate trace CO from H₂-rich gas.