铜源对Cu/ZSM-5催化剂氨选择性催化还原NO的影响  

Effects of Cu sources on catalytic performance of Cu/ZSM-5 for selective catalytic reduction of NO with NH_3

作　　者：郑昌坤 韩帅 叶青[1] ZHENG Chang-kun;HAN Shuai;YE Qing(College of Environmental and Energy Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学环境与能源工程学院,北京100124

出　　处：《化学工程》2018年第9期23-27,42,共6页Chemical Engineering(China)

基　　金：国家自然科学基金资助项目(21277008;20777005);北京市自然科学基金项目(8082008)

摘　　要：采用旋蒸法,以硝酸铜、醋酸铜、硫酸铜为前驱体分别制备了3种不同铜源的Cu/ZSM-5分子筛催化剂。评价了不同铜源Cu/ZSM-5催化剂的氨选择性催化还原(NH_3-SCR)活性,并通过XRD、N2-吸附/脱附、H2-TPR、XPS和NH_3-TPD等技术对催化剂的物化性质进行了表征。结果表明:铜源对Cu/ZSM-5分子筛催化剂中低温段的氨选择性催化还原NO性能有较大影响。所制备的3种不同铜源Cu/ZSM-5催化剂活性在中低温段有明显差异,以硝酸铜为前驱体的Cu(N)/ZSM-5催化剂取得最佳的中低温活性,在190℃时NO转化率达91%。表征结果表明,引入不同铜盐种类对分子筛的结构影响不大,但对其铜物种存在形式、酸位数量等影响较大。Cu(N)/ZSM-5样品具有最多的孤立Cu^(2+)物种以及中酸位数量。孤立的Cu^(2+)有利于增强催化剂低温还原性能,中等强度酸性位点有利于NH_3的吸附与活化,因此Cu(N)/ZSM-5样品中低温段NH_3-SCR催化性能最佳。Three kinds of Cu/ZSM-5 molecular sieve catalysts with different copper sources(copper nitrate,copper acetate and copper sulfate)were prepared by rotary evaporation method.NH 3 selective catalytic reduction(NH 3-SCR)reaction activity of Cu/ZSM-5 catalysts was investigated and physicochemical properties of the samples were characterized by XRD,N2 adsorption-desorption,H 2-TPR,XPS and NH 3-TPD techniques.The results show that the different of copper source has a great influence on the medium and low temperature catalytic performance of Cu/ZSM-5 catalysts.The activity of the three Cu/ZSM-5 catalysts is significantly different at medium and low temperature.And the sample with copper nitrate as precursor obtains the best medium and low temperature activity.The NO conversion of Cu(N)/ZSM-5 reaches 91%at 190℃.Characterization results show that the doping of different kinds of copper salt hardly affects the structure of ZSM-5.Moreover,the copper source affects the forms of copper species and the number of acid sites obviously.Cu(N)/ZSM-5 sample possesses the largest number of isolated Cu^2+species and moderately acidic sites.Isolated Cu 2+is beneficial to enhance the low temperature reduction performance of the catalyst,and moderately acidic sites are favorable for the adsorption and activation of NH3.Therefore,the Cu(N)/ZSM-5 sample has the best medium and low temperature catalytic performance.

关 键 词：铜源 Cu/ZSM-5 催化剂 氨选择性催化还原 氮氧化物去除 

分 类 号：O643[理学—物理化学]