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

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.