Influence of calcination temperature on the catalytic activity of Mn/TiO2 for NO oxidation

The influence of calcination temperature on the catalytic activity of Mn-based catalysts impregnated on TiO2 for the oxidation of NO was studied. The results showed that, relatively low calcination temperature was beneficial to promote the catalytic activity of Mn/TiO2 catalysts. The catalysts were characterized by various techniques to study the influence mechanism of calcination temperature, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR) and O2 temperature programmed desorption (O2-TPD). It could be concluded that Mn2O3 played a dominant role in the process of NO oxidation, and the relatively lower calcination temperature could enhance the percentage of Mn2O3 in MnOx, as well as promote the dispersion of MnOx on TiO2, thus raising the catalytic activity of Mn/TiO2. When the calcination temperature was higher than 500 °C, the agglomeration began to appear, and the crystalline phase of TiO2 was transformed from anatase to rutile, Mn2O3 was, as well, transformed from amorphous phase to crystalline phase. The test results of H2-TPR and O2-TPD showed that relatively lower calcination temperature was beneficial to the reduction ability of Mn/TiO2 catalysts and the desorption of chemisorbed O2- on catalysts surface, the interaction of the two factors resulted in good mobility of chemisorbed O2- on catalysts surface, which was good for the activity of catalysts.