Xiaoyu Fan

Catalytic reduction of NOx with NH3 over different-shaped MnO2 at low temperature

MnO(2) nanotubes, nanorods, and nanoparticles were prepared using a hydrothermal method, after which the different activities for selective catalytic reduction (SCR) of nitrogen oxides (NO(x)) were compared. MnO(2) nanorods performed the highest activity for reduction of NO(x) under a gas hourly space velocity of 36,000 h(-1) with conversion efficiencies of above 90% between 250 and 300 °C; it also had the highest removal efficiency of 98.2% at 300 °C. From the analysis of X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption, and temperature-programmed reduction, we can ascribe the high activity of MnO(2) nanorods to low crystallinity, more lattice oxygen, high reducibility, and a large number of strong acid sites. The apparent activation energy of the SCR reaction on the surface of nanorods was calculated to be 20.9 kJ/mol, which favored the reaction better than the other catalysts.

Preparation of MnOx/TiO2 composites and their properties for catalytic oxidation of chlorobenzene

MnO(x)/TiO(2) composites with different atomic ratio of Mn/Ti were prepared by sol-gel, solvothermal and coprecipitation method, respectively. The catalytic tests on chlorobenzene (CB) removal ability of all 15 catalysts were performed in a fixed-bed flow reactor and compared to each other. Experimental results showed that when the atomic ratio of Mn/Ti reached 1:4, the activity of the catalysts prepared by three methods reached their highest value, particularly the catalyst with the Mn/Ti atomic ratio of 1:4 prepared by sol-gel method showed higher catalytic activity than the catalysts with the same atomic ratio prepared by other methods at temperature between 100 and 300 degrees C. From the microstructure characterization by XRD, SEM, EDS, BET, and TPR, it could be known that the combined TiO(2) phases of anatase and rutile and a good dispersion of manganese oxides contributed to a good catalytic performance in the catalyst prepared by the sol-gel method.