Catalytic Oxidation Activity of NO on TiO<sub>2</sub>-Supported Mn-Co Composite Oxide Catalysts

Abstract

Globally, NOx is one of the most widespread pollutants. It is generated mainly from the burning of fossil fuels, and NO is very difficult to remove because of its capacity to be dissolved in water. The catalytic oxidation method can be used to convert NO to NO2, which is soluble in water and can be removed using desulfurization devices. Here, a series of TiO2-supported Mn-Co composite oxide catalysts were prepared using the impregnation method. The results of catalytic activity tests showed that the addition of Mn enhanced the efficiency of NO oxidation. Significantly, with 6% doping amounts, Mn (0.3)-Co(0.7)/TiO2 showed the best activity of 88% NO conversion at 300 degrees C. X-ray diffraction (XRD), N-2 adsorption/desorption, hydrogen temperature-programmed reduction (H-2-TPR), oxygen temperature-programmed desorption (O-2-TPD), and in-situ diffuse reflectance Fourier transform infrared (in-situ DRFTIR) spectroscopy were used to characterize the catalysts. The results indicated that when the doping amount was 6%, the Mn enhanced the specific surface areas and pore volumes, which improved the dispersion of the active component over the TiO2 support. The co-doping of manganese into the Co/TiO2 also enhanced the oxygen desorption capabilities of the catalysts, which improved their reduction abilities. In addition, bridge NO3-, the key intermediate, was converted into NO2; this conversion was also enhanced by the presence of Mn on the Co/TiO2 catalyst. All of the above reasons account for the high NO catalytic oxidation activity of the supported Mn-Co composite oxide catalysts.