Structural features and catalytic performance in CO preferential oxidation of CuO–CeO2 supported on multi-walled carbon nanotubes

Abstract

Multi-walled carbon nanotube (MWCNT) supported CuO–CeO₂ catalysts were prepared using an impregnation method aided by an ultrasonication treatment. The structural features of the catalysts were extensively characterized by XRD, TGA, H₂-TPR, XPS, TEM and Raman spectroscopy. The catalytic performance in the preferential oxidation of CO in a H₂-rich stream was extensively investigated with respect to the influences of Cu/Ce ratios, the different support materials and the presence of CO₂ and H₂O in the feed stream. In contrast to those supported on other materials, the catalytic performance was greatly enhanced for the MWCNT-supported CuO–CeO₂ catalysts, which was discussed in terms of the synergistic interactions between Cu–Ce mixed oxides and MWCNT. The optimized catalyst with a Cu/Ce ratio of 5/5 can achieve complete CO conversion and high selectivity toward CO₂ in a wider temperature range as well as favorable performance under the simulated reformatted gas mixture. The deactivation of CuO–CeO₂ catalysts supported on MWCNT at elevated temperatures was also discussed in relation to the temperature-dependent in situ XAFS spectra during CO-PROX reaction.