Interactive effects of NOx synergistic and hydrothermal aging on soot catalytic combustion in Ce-based catalysts

The Thermal gravimetric analysis (TGA) with In-situ Fourier transform infrared Spectrometer (In-FTIR) of fresh/hydrothermal aging Ce-based catalysts was carried out for the soot oxidation at different transition metal Mn, alkali metals K, precious metals Ag and rare earth metal Zr doping which used to extend the hydrothermal aging resistance of CeO 2 catalysts. The comprehensive combustion index S , combustion stability index R w and peak temperature T p from TG-DTG curves were extracted to evaluate the soot catalytic combustion performance, and the NO 2 /NO ratio during the combustion process was also measured to analyze the NOx synergistic oxidation performance. The effect of metal oxide doping type, doping ratio and hydrothermal aging time on S, R w , T p and NO 2 /NO ratio was evaluated to reveal the change in soot catalytic combustion performance. The result shows that, compared with PU, the NOx synergistic oxidation performance of various metal oxides modified Ce-based catalysts ranked as K > Ag > Mn > Zr. With the metal oxide doping ratio increased, the soot catalytic combustion performance of K and Zr metal oxides modified Ce-based catalysts decreased, Mn and Ag metal oxides modified catalyst increased. After hydrothermal aging treatment, the NOx synergistic oxidation performance of various metal oxides modified Ce-based catalysts ranked as K > Ag > Mn > Zr. This work is helpful to reveal the basic mechanism of hydrothermal aging metal oxide modified Ce-based catalyst and NOx during soot catalytic combustion process.