Ceria-modified Al-Mn-pillared clay catalysts for the selective catalytic reduction of NO with NH3 at low temperatures

The yCe/Al-Mn-pillared interlayered clay (PILC, y [Ce content] = 8-9 wt%) catalysts were prepared using the impregnation method. Catalytic activities of the materials for the selective catalytic reduction (SCR) of NO with NH3 at low temperatures were evaluated, and physicochemical properties of the samples were characterized by X-ray diffraction, N-2 adsorption-desorption, temperature-programmed reduction, ammonia temperature-programmed desorption, X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy techniques. It is found that introduction of cerium enhanced NO conversions at low temperatures, and the 8Ce/Al-Mn-pillared sample showed the highest NO conversion (92% at 300 degrees C). The superior catalytic activity of 8Ce/Al-Mn-PILC was associated with the change in active component and increases in amounts of the surface chemisorbed oxygen species and the acid sites after ceria loading. Additionally, the SCR reaction mechanism over 8Ce/Al-Mn-PILC followed both Langmuir-Hinshelwood and Eley-Rideal mechanisms, with the former being dominant.