Ceria Modified MnOx/TiO2-Pillared Clays Catalysts for Selective Catalytic Reduction of NO with NH3 at Low Temperature

Titania-pillared clays (TiO2-PILC) were synthesized by ion exchange and manganese was introduced as the active phase. The catalytic behavior of the xMn/TiO2-PILC catalysts was studied for the low-temperature selective catalytic reduction (SCR) of NO with NH3. A series of Ce-doped 8%Mn-yCe/TiO2-PILC catalysts were prepared and evaluated for their performance in the low-temperature SCR of NO with NH3, their resistance to water vapor (H2O), and their resistance to sulfur dioxide (SO2). It was found that the NO conversion properties of the 8%Mn/TiO2-PILC catalysts could be significantly improved by adding Ce and all the catalysts gave high resistance to H2O but were sensitive to SO2. The catalyst with a Ce loading of 2% gave 95% NO conversion at 220 degrees C and exhibited a moderate SO2-poisoning resistance compared with the other catalysts. X-ray diffraction, N-2 adsorption-desorption, temperature-programmed desorption of NH3, X-ray photoelectron spectroscopy, and temperature-programmed reduction of H-2 were used to characterize the properties of the catalysts. The addition of Ce improved the diffusion of Mn on the surfaces of the catalysts, which enhanced the surface acidity and improved the reduction properties of the catalysts and these were the main influencing factors for the low-temperature SCR.