基于低碳硫醇高效催化降解可控ZSM-5型催化剂的构建与催化机理研究

Gaseous sulfur species is one of the main ingredients that would be closely associated with the formation of the increasing serious air pollution problems (such as haze), and the reducing emission of sulfur species is of great urgency and facing unprecedented pressure and challenge in China. The project will be focused on the effective removal of organic sulfur species together with the source utilization of rice husk ash to synthesize zeolites with high-value. However, the corresponding basic researches for removing organic sulfur species with respect to inorganic sulfur species is relatively weak in China and the synthesis of zeolites by using rice husk ash as the silica source is suffering from the drawbacks (low zeolites yield and alkali pollution). In the project, we put forward an innovative research idea, high-performance and modified ZSM-5 catalysts will be synthesized with rice husk ash as the silica source and by adjusting the molar ratio of Si/Al and/or the addition of rare metal via a novel solid synthesis route, which will be used to effectively decompose organic low-carbon mercaptan (methaethiol, ethanethiol as well as their mixtures). The research will provide an environment-friendly and inexpensive method to synthesize ZSM-5-type molecular sieves with high-performance. Furthermore, excellent economic, social and environmental benefits will also be achieved. Implementation of this project, the achievements would provide theoretical basis to synthesize excellent performance industrial catalysts as well as other advanced environmentally functional materials by using rice husk ash. It can also provide valuable experiences to design excellent catalysts for effectively decomposing other organic thiol. Furthermore, it is of great significance to reduce sulfur emission as well as VOCs emission.

气态硫物种是导致我国日益严峻雾霾大气污染的主要原因之一，其减排刻不容缓且遇到前所未有的压力与挑战。本项目针对我国有机硫物种高效脱除的基础研究相对薄弱以及稻壳灰高值资源化合成分子筛的难点问题（产率低与碱液污染），提出“稻壳灰高值资源化利用的新方法协同低碳有机硫醇（甲、乙硫醇及其混合物）高效催化降解”的研究思路。拟以稻壳灰为硅源，通过调控合成体系中的硅铝（Si/Al）比和引入稀土金属助剂，构建固相无溶剂合成体系，合成高性能ZSM-5型分子筛，并将其应用于低碳硫醇的高效催化降解与机理研究。本研究既提供一种廉价且环境友好合成ZSM-5与稀土改性ZSM-5型分子筛的新方法，又可获得良好的经济和环境效益。研究成果可为我国稻壳灰高值资源化制备性能优良的工业催化剂和其他环境功能材料奠定较好的理论基础，也可为其他有机硫醇高效降解催化剂的设计提供可借鉴的宝贵经验，其对我国硫减排和VOCs减排具有积极的意义。

本项目针对我国有机硫物种高效脱除的基础研究相对薄弱以及稻壳灰高值资源化合成分子筛的难点问题（产率低与碱液污染）为研究目标，以稻壳灰为硅源，通过调控合成体系中的硅铝（Si/Al）比和引入稀土金属助剂，构建固相无溶剂合成体系，合成高性能ZSM-5型分子筛。对实际催化反应条件进行了全面的探究，确定最佳反应温度、空速、浓度以及比例等反应条件，以确保最佳的催化性能。利用氮气吸脱附、XRD、H2-TPR、NH3/CO2-TPD、CH3SH/C2H5SH-TPD和XPS等表征对催化剂的微观结构及活性中心调变规律进行探究，并借助于动力学等理论计算取得如下主要结论：不同稀土金属改性HZSM-5分子筛催化剂，大大提高了其催化分解恶臭气体甲乙硫醇的活性，其中La/HZSM-5和Ce/HZSM-5表现出良好的催化活性，这主要是由于不同稀土改性后的HZSM-5分子筛的原有结构没有被破坏且形成新的介孔-微孔多级孔结构；且调节HZSM-5分子筛表面的酸碱性，减少了酸性中心数量，增加了碱性中心的数量，抑制了积碳的形成，从而提高了催化剂的催化性能。本项目通过动力学理论计算证实了在甲乙硫醇混合体系中，降解乙硫醇需要的活化能更低。因此，乙硫醇比甲硫醇更易分解。通过调控反应条件的参数，探究了甲乙混合体系最佳反应条件，为有机低碳硫醇的高效脱除研究工作提供理论依据。已发表学术论文25篇，其中SCI、EI收录20篇；申请发明专利5项，培养研究生7名。