Cu-SAPO-44的制备及氨选择性催化还原氮氧化物的性能  

Preparation and performance of Cu-SAPO-44 for selective catalytic reduction of NO_x with NH_3

作　　者：李瑞睿 孔祥成 王晓[1] 张娜娜 辛颖[1] 李倩[1] 张昭良[1] LI Ruirui;KONG Xiangcheng;WANG Xiao;ZHANG Nana;XIN Ying;LI Qian;ZHANG Zhaoliang(School of Chemistry and Chemical Engineering, University of Ji＇nan, Ji＇nan, 250022, China;Jining Environmental Protection Monitoring Station, Jining, 272000, China)

机构地区：[1]济南大学,化学化工学院,济南250022 [2]济宁市环境保护监测站,济宁272000

出　　处：《环境化学》2018年第6期1264-1271,共8页Environmental Chemistry

基　　金：国家自然科学基金(21477046); 山东省重点研发计划(重大关键技术)(2016ZDJS11A03)资助

摘　　要：氨选择性催化还原(NH_3-SCR)是消除柴油车尾气NO_x的主要技术,Cu-微孔分子筛催化剂展现了优异的活性和稳定性.本文采用直接离子交换法(DIE)和传统离子交换法(CIE)分别制备了Cu-SAPO-44催化剂.X射线粉末衍射(XRD)表征发现,在CIE过程中,硝酸铵的交换导致了SAPO-44结晶度下降,因此,CIE样品的比表面积降低.氨气程序升温脱附(NH_3-TPD)表明,DIE样品比CIE样品拥有更多的酸性位和较强的NH_3吸附能力.同时,氢气程序升温还原(H2-TPR)表明,DIE样品更容易发生氧化还原反应.然而,电感耦合等离子体发射光谱仪(ICP-AES)测得的Cu含量,DIE样品远低于CIE样品.对比两者的脱硝活性,发现铜含量较低的DIE样品和铜含量较高的CIE样品在250℃均可达到98%的NO_x转化率和接近100%的N2选择性.动力学结果表明,DIE样品的本征活性(转换频率)略高于CIE样品.由此,Cu-SAPO-44催化剂在NH_3-SCR领域具有潜在的广阔应用前景.Selective catalytic reduction of NOxwith NH3（NH3-SCR） is regarded as one of the primary technologies for de NOxin diesel exhaust.Cu-based microporous zeolites are widely used in NH3-SCR due to their its excellent SCR activity and high thermal stability.In this paper,Cu-SAPO-44 zeolites were synthesized by direct ion-exchange（DIE） and conventional ion-exchange（CIE）methods.X-ray powder diffraction（XRD） results indicate that the DIE sample experienced a significant drop in crystallinity during the ion-exchange stage of ammonia nitrate.Therefore,the specific surface area of the CIE sample decreased.Temperature-programmed desorption of NH3（NH3-TPD） showed that the DIE sample possesseed more acid sites and higher NH3 adsorption capacity compared with the CIE sample.Simultaneously,temperature-programmed reduction with H2（H2-TPR） illustrated that the DIE sample exhibited better redox ability.However,inductivelycoupled plasma-atomic emission spectromety（ICP-AES） revealed that the DIE sample had much lower Cu loading in comparison with the CIE sample.Interestingly,both the DIE and CIE samples achieve 98% NOxconversion and approximately 100% N2 selectivity at 250 ℃.The kinetics study demonstrated that the intrinsic activity（TOF） of the DIE sample was slightly higher than that of the CIE sample.Thereby,the Cu-SAPO-44 catalyst has a great potential in the NH3-SCR field.

关 键 词：直接离子交换 Cu-SAPO-44 氨选择性催化还原 

分 类 号：O643.3[理学—物理化学] X734.2[理学—化学]