Au/MnO2-TiO2 catalyst for preferential oxidation of carbon monoxide in hydrogen stream

摘要

The catalytic activity of nanosize gold catalysts supported on MnO2-TiO2 and prepared by deposition-precipitation method has been investigated for preferential oxidation of carbon monoxide in H2 stream.The catalysts were characterized by inductively coupled plasma-atomic emission spectroscopy,X-ray diffraction,nitrogen sorption,transmission electron microscopy,and X-ray photoelectron spectroscopy.The influence of pH in the preparation process and the amount of MnO2 loading on the catalytic properties of the Au/MnO2-TiO2 catalysts were also studied.Fine dispersion of gold nanoparticles on all the supports was obtained.Especially,Au/MnO2-TiO2 with MnO2/TiO2 mol ratio of 2:98,showed a mean Au particle size of 2.37 nm.The nanosized support constrained the size of gold.The addition of MnO2 on Au/TiO2 catalyst improved the selectivity of CO oxidation without sacrificing CO conversion in hydrogen stream between 50 and 100 °C.This could be attributed to the interactions of gold metal with MnO2-TiO2 support and the optimum combination of metallic and electron-deficient gold on the catalyst surface.