SO_4~(2-)改性对Ce、Ti基催化剂NH_3-SCR脱硝性能的影响

采用共沉淀法制备了几种不同的金属氧化物催化剂(Ce-Pr-Ox、Ce-Y-Ox、Ti-PrOx、Ti-Y-Ox、Ti-Al-Ox),并对其进行了硫酸盐改性.实验同时考察了SO2-4改性对催化剂氨选择性催化还原(NH3-SCR)活性和催化剂结构组成的影响.经SO2-4改性的催化剂,NOx转化率在低温和高温均有显著提高,其中,活性最好的Ce-Pr-Ox在350~500℃范围内转化率接近100%.XRD、IR分析结果表明,催化剂经硫酸盐改性后,催化剂出现了结晶态硫酸盐;催化剂中存在M-SO2-4(M=Al,Pr和Y)键,表明了金属氧化物与硫酸盐发生了相互作用.而经SO2-4改性后催化剂优越的SCR脱硝性能与催化剂酸性位点增加密切相关.

Enhanced Effect of SO2-4 on Ce and Ti-Based Catalysts for Selective Catalytic Reduction of NO x with NH3

A series of metal oxide catalysts （Ce-Pr-Ox,Ce-Y-Ox,Ti-Pr-Ox,Ti-Y-Ox,Ti-Al-Ox）are prepared by co-precipitation method and modified by SO2-4 for selective catalytic reduction of NOx with NH3 .The influences of SO2-4 modification on NH3 -SCR activity and structures on Ce and Ti-based catalysts are investigated.It is implied by the results that the catalytic performance of catalysts modified by SO2-4 is signifi-cantly enhanced at both low and high temperatures.Furthermore,nearly 100%NOx conversion over the Ce-Pr-Ox catalyst could be obtained throughout the temperature window of 350—500 ℃,which exhibits the highest level of NH3 -SCR activity.It is also inferred from the XRD analysis that the crystalline sulfate species are de-tected for the SO2-4 modified catalysts.Besides,the existence of sulfate species （M-SO2-4 ：M=Al,Pr and Y） is found on the SO2-4 modified catalysts by the analysis of XRD and IR.Thus,it could be concluded that there exists interaction among SO2-4 and other metal.The superior SCR activity might be attributed to the increase a-mount of acid cites over the SO2-4 modified catalysts.