A novel ultrasonic-modified MnOx/TiO2 catalyst was prepared and compared with two different kinds of MnOx/TiO2 catalysts in the process of low-temperature selective catalytic reduction of NO with NH3. 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 MnOx/TiO2 catalyst preparation. In this study, ultrasonic process significantly improved the dispersion behavior and surface acid property of manganese oxide on TiO2 as well as the catalytic activity, especially at temperature below 120 degrees C. The NO conversion could reach 90% at 100 degrees 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. (C) 2011 Elsevier Inc. All rights reserved.