不同Ce/Ba比对柴油机NSR催化剂性能的影响

Effect of Different Ce/Ba Ratios on the Performance of the Diesel Engine NSR Catalysts

为了降低柴油机NO_x排放,通过浸渍法制备了不同Ce/Ba比的NOx存储还原（NSR）催化剂：x Ce（25-x）Ba/γ-Al_2O_3（x为质量分数,且x=8-12）,并利用扫描电子显微镜（SEM）、透射电子显微镜（TEM）、傅里叶变换红外光谱（FT-IR）以及比表面积分析仪（BET）对催化剂的性能进行表征。结果表明,在NSR催化剂中存在Ce O_2晶粒,且以近似球状均匀分布在催化剂表面,粒径尺寸为（20~50）nm;在催化剂表面分布有大量孔洞,且随着x的增大,孔容和孔径呈现先增大后减少的趋势。当Ce/Ba质量比为10：15时,晶粒分布较其它配比均匀,催化剂表面的孔容和孔径数值最大,更有利于吸附。

NOx storage reduction （NSR） catalyst with different Ce/Ba ratios, xCe（25-x）Ba/~ -A1203 （x is the mass fraction, and x= 8-12）, were prepared by impregnation method in order to reduce NOx emissions from the diesel engine. The microstructures and properties of catalysts were characterized by Scanning Electron Microscope（SEM）, Transmission Electron Microscope（TEM）, Fourier Transform Infrared Spectroscopy （FT-IR） and Brunauer Emmett Teller （BET）. The results show that CeO2 gra/ns exist in the NSR catalyst with the size range from 20 to 50 rim, which are in the form of near-spherical and relative uniformly distributed on the catalyst surface. In addition, there are large amounts of holes on the surface of the catalyst. With the increase of x, pore volume and pore size generally increase at the initial stage and followed by decreasing. When the ratio of Ce/Ba is 10：15, the distribution of grain is more uniformly than that of ather ratios, and the most pore volume and pore size are observed on the surface of the catalyst, which are benefit for NOx absorption.