Preferential oxidation of CO in a H_2-rich stream over multi-walled carbon nanotubes confined Ru catalysts

摘要

Multi-walled carbon nanotubes (MWNTs) confined Ru catalysts were prepared by a modified procedure using ultrasonication-aided capillarity action to deposit Ru nano-particles onto MWNTs inner surface. The structure properties of MWNTs supports and Ru catalysts were extensively characterized by XRD, TGA, H_2-TPR, XPS, TEM, FTIR and Raman spectra. The catalytic performance in the preferential oxidation of CO in a H_2-rich stream was examined in detail with respect to the influences of Ru loading, MWNTs diameter, various pretreatment conditions, and the presence of CO_2 and H_2O in the feed stream. In contrast with Ru catalysts supported on MWNTs external surface and other carbon materials, the superior activity was observed for the MWNTs-confined Ru catalyst, which was discussed intensively in terms of the confinement effect of carbon nanotubes. The optimized catalyst of 5 wt.% Ru confined in MWNTs with diameter of 8-15 nm can achieve the complete CO conversion in the wider temperature range and the favorable stability at 80 ℃ under the simulated reformatted gas mixture, which proves a promising catalyst for preferential CO oxidation in H_2-rich stream.