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摘要以柴油机尾气为代表的移动源尾气中所含有的氮氧化物(NOx)是主要的大气污染物之一,需要得到严格的控制。在固定源脱硝中使用的NH3-SCR技术也是柴油机尾气处理中最有效的手段。CHA型小孔分子筛SAPO-34因为其优异的催化活性窗口及良好的水热稳定性成为柴油机SCR脱硝的优秀选择。
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本论文采用双模版剂水热合成SAPO-34分子筛，并在其前驱液中加入Cu，Mn，Fe，Co，V等过渡金属离子，制备过渡金属改性SAPO-34分子筛。其中Cu，Mn及二者共同改性的催化剂展现了很好的NH3-SCR催化活性。使用XRD, BET, SEM, TPR, TPD等手段对各组样品进行了表征。结果表明分子筛表面的弱酸性位点增多及氧化还原性能增强是改性后的分子筛具有良好活性的主要原因。对Cu-Mn改性分子筛进行了水热稳定性测试，结果表明在经过了处理后的分子筛仍能保持良好的活性。21398
关键词 过渡金属 改性 小孔分子筛 脱硝
毕业论文设计说明书（论文）外文摘要
Title Transition Metal Modified SAPO-34 Small Pore Zeolite for the Diesel Engine NH3-SCR DeNOx Application
Abstract
Nitrogen Oxides (NOx) from mobile sources, especially diesel engine, is one of the major atmospheric pollutants which need strictly after treatment. As is like stationary sources, selective catalytic reduction (SCR) of NOx by NH3 is still one of the most effective technologies of NOx emissions for diesel engine exhaust gas treatment. The CHA type small pore SAPO-34 zeolite possess better hydrothermal stability and broader temperature range, which become an excellent choice for Diesel NH3-SCR.
The SAPO-34 was hydrothermal pressure synthesized using double structure directing agent, transition metal (Cu，Mn，Fe，Co，V) was added into the precursor solution to prepare the transition metal modified SAPO-34 zeolite. Both Cu, Mn and Cu-Mn samples showed excellent SCR performance. XRD, BET, SEM, TPR, TPD were used to investigating the physical and chemical properties of samples. Results indicated that the increasing of weak acid sites and the enhancement of redox performance were the main reason for the good activity for modified samples.A hydrothermal treatment was taken for Cu-Mn sample, the sample maintained a good activity after the treatment.
Keywords Transition Metal Modification Small Pore Molecular Sieves DeNOx
目录
1绪论 1
1.1 课题背景和意义 1
1.1.1 NOX的危害 1
1.1.2 NOX的产生原因及其生成机理 1
1.2 NOX的控制技术 2
1.2.1 NOX控制技术的分类 2
1.2.2 SCR技术 2
1.3 移动脱硝催化剂的特征 4
1.3.1 柴油机排气温度的影响 4
1.3.2 柴油机排放量和组成影响 4
1.3.3 柴油机运行环境的影响 4
1.4 SAPO-34分子筛 5
1.4.1 SAPO-34分子筛的结构 5
1.4.2 SAPO-34分子筛的合成方法及合成条件 5
1.4.3 SAPO-34分子筛的金属改性 7
1.5本文主要的研究内容与研究方法 8
2 实验 9
2.1 主要仪器和试剂 9
2.2 催化剂的制备 11
2.2.1 用水热合成方法制备SAPO-34分子筛 11
2.2.2 水热合成法制备金属改性的SAPO-34分子筛 12
2.3 NH3-SCR固定床反应活性测试 13
2.4 XRD表征 13
2.5 程序升温脱附（TPD）表征 14