【摘要】 氨选择性催化还原（NH₃-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（NH₃-TPD）表明,DIE样品比CIE样品拥有更多的酸性位和较强的NH₃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NH₃-SCR领域具有潜在的广阔应用前景.更多还原

【Abstract】 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.更多还原