Novel ultrasonic-modified MnOx/TiO_2 for low-temperature selective catalytic reduction (SCR) of NO with ammonia

摘要

A novel ultrasonic-modified MnO_x/TiO_2 catalyst was prepared and compared with two different kinds of MnO_x/TiO_2 catalysts in the process of low-temperature selective catalytic reduction of NO with NH_3. The physicochemical properties of the catalysts were studied by using various characterization techniques, such as Brunauer-Emmett-Teller (BET) surface measurement, X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and in situ Fourier transform infrared spectroscopy (in situ FT-IR). The ultrasonic-modified process introduced ultrasound in the solution impregnation step of traditional impregnation method for MnO_x/TiO_2 catalyst preparation. In this study, ultrasonic process significantly improved the dispersion behavior and surface acid property of manganese oxide on TiO_2 as well as the catalytic activity, especially at temperature below 120°C. The NO conversion could reach 90% at 100°C. For the novel ultrasonic-modified catalyst, the combination analysis of XRD and HRTEM confirmed that manganese oxide was in a highly dispersed state and Ti and Mn had strong interaction. Furthermore, in situ FT-IR studies revealed that there were significant amounts of Lewis acidity and high Mn atom concentration on the surface of the novel catalysts.