ZSM-5分子筛改性及Hg0吸附动力学机理

As China's coal use and mercury emissions both rank first in the world, China has become one of the globe's most seriously polluted areas. Therefore, it’s urgently needed for flue gas demercuration absorbent and its corresponding technological research. Our project aims the Hg0 removing as the object of study, adopts the method of combining molecular simulation, theoretical analysis and experimental testing, majorly focuses on the relevant research work of strong oxidizing materials’ modification of ZSM-5 zeolite to prepare efficient mercury removal absorbent and adsorption kinetics mechanism of mercury. The project will have important theoretical and engineering value on improving the flue gas mercury removal efficiency and reducing application costs. In the project, we firstly employ MS software to conduct molecular simulation of ZSM-5 zeolite spatial structure, and then prepare the modified ZSM-5 zeolite demercuration adsorbent by using the method of solid ion exchange, furthermore, we establishes adsorption kinetics model of modified ZSM-5 Hg0 zeolite through the application of the instrumental characterization and Hg0 adsorption performance test, especially, we emphasize on the discussion of Hg0 adsorption rate and dynamics of the process from the perspective of kinetics, reveal the mechanisms of Hg0 oxidation, adsorption and separation and to explore its application in an electrostatic dust removal system. We make sure that our research will provide a theoretical basis and applied accumulation for the development of efficient flue gas mercury absorbent. Based on the analysis test platform of "State Tungsten and Rare Earth Product Quality Inspection Center", our groups have accumulated a certain amount of research experiences and phased findings in the field, possessed the basis and conditions of implementing and completing this study.

中国的煤炭用量和汞排放量均居世界首位，是全球范围内汞污染最严重的地区之一，迫切需要烟气脱汞吸附剂及技术的研发。本项目以难脱除的Hg0为研究对象，采取分子模拟、试验测试和理论分析相结合的方法，拟将活性物质改性的ZSM-5分子筛用于制备高效脱汞吸附剂，并研究其对汞的吸附动力学机理，对提高脱汞效率，降低应用成本具有重要理论意义和工程价值。项目拟先应用MS软件对ZSM-5分子筛空间结构等进行分子模拟，再采用固体离子交换法制备改性ZSM-5分子筛脱汞吸附剂，通过仪器表征和汞吸附性能试验，建立改性ZSM-5分子筛对汞的吸附动力学模型，重点探讨汞吸附速率和动力学过程，揭示汞氧化、吸附机理，并探索在静电除尘系统中应用，为高效烟气脱汞吸附剂的开发提供理论基础和应用经验。申请人在该领域已积累一定的研究经验和阶段性研究结果，且有“国家钨与稀土产品质量检验检测中心”分析测试条件，具备实施和完成此研究的基础和条件。

针对全球范围内汞污染严重的问题，本项目以烟气中难脱除的Hg0为研究对象，采取MS分子模拟、试验、仪器表征和理论分析相结合的方法，系统开展了最佳分子筛空间结构模型及最佳负载活性物质的分子模拟筛选、ZSM-5分子筛吸附Hg0的分子模拟及试验、改性ZSM-5分子筛脱汞吸附剂制备、Fe-ZSM-5分子筛吸附性能及机理、Mn-ZSM-5分子筛吸附性能及机理、Cu-ZSM-5分子筛吸附性能及机理等方面的研究，取得一批重要研究成果：①应用MS软件从众多的载体材料中，根据项目研究的需要（将Hg0有效氧化为易脱除的Hg2+），模拟筛选出硅铝比为50的制备脱汞吸附剂的载体材料ZSM-5分子筛和强氧化性活性物质CuCl2、K2FeO4、KMnO4。②创新了两种ZSM-5分子筛改性制备脱汞吸附剂的方法，即固态离子交换法和液态离子交换法，制备了Cu-ZSM-5、Fe- ZSM-5、Mn-ZSM-5分子筛脱汞吸附剂，并通过实验得到了最佳的制备参数条件。Mn-ZSM-5分子筛脱汞吸附剂的最佳制备条件为： ZSM-5分子筛与K2MnO4质量浓度为10:2.6，焙烧温度为400℃；吸附反应时间为170min，吸附反应温度为80℃；Fe-ZSM-5分子筛脱汞吸附剂的最佳制备条件为： ZSM-5分子筛与K2FeO4质量浓度为10:1.5，焙烧温度为250℃；吸附反应时间为70min，吸附反应温度为80~120℃；Cu-ZSM-5分子筛脱汞吸附剂的最佳CuCl2负载浓度为2.5%，吸附反应时间为25min，吸附反应温度为30℃。改性ZSM-5分子筛的脱汞效率比未改性ZSM-5分子筛的脱汞效率高了30~44%。③通过MS模拟和BET、XRD、SEM、FTIR、XPS、EDS表征分析，揭示了Cu-ZSM-5分子筛、Fe-ZSM-5分子筛、Mn-ZSM-5分子筛脱汞吸附剂的动力学机理，对Hg0的吸附主要是化学吸附，且吸附服从Mars-Maessen机制。这些成果为新型脱汞吸附剂的开发提供了新的思路、新的方法和理论基础，这对开发新型高效脱汞吸附剂的材料设计和优化具有重要的理论意义和工程价值。