화학공학소재연구정보센터
Catalysis Letters, Vol.128, No.3-4, 475-482, 2009
The Effect of Al2O3 Doping into TiO2-ZrO2 on the Storage and Sulfur-resistance Performance of the NOx Trap Catalyst Pt/K/TiO2-ZrO2
A series of lean-burn NOx trap (LNT) catalyst Pt/K/Al2O3-TiO2-ZrO2 were prepared by sequential impregnation with the support synthesized by coprecipitation. The effect of Al2O3 doping into TiO2-ZrO2 on the storage and sulfur-resistance performance of the catalyst Pt/K/TiO2-ZrO2 was investigated carefully. In situ DRIFTS spectra show that the NOx is mainly stored as nitrate at the optimal temperature of similar to 350 degrees C. The NOx storage capacity (NSC) of Pt/K/TiO2-ZrO2 was greatly improved by Al2O3 doping due to the remarkably increased specific surface area and the decreased Ti content. The results of sulfation and regeneration by H-2-TPR reveal that the sulfur on Al2O3-TiO2-ZrO2 supported catalysts is easier to be removed, making them possess much better sulfur-resisting ability than TiO2-ZrO2 or Al2O3 supported ones. The NSC recovery efficiency of Al2O3-TiO2-ZrO2 supported catalysts can reach as high as 81-96% while only 30.4 and 62.5% were achieved for the catalysts supported on pure Al2O3 and TiO2-ZrO2, respectively. The doped catalyst with the Al/(Ti + Zr) atomic ratio of 3:1 always shows the highest NSC before or after sulfation-regeneration.