褐煤微波催化热解过程中单环精细化合物形成及焦油产物分布定向调控机制

The macromolecular structure of lignite contains large amount of single-ring aromatic structural units. The characteristics of its molecular aromatic structures are very suitable for production of single-ring aromatic fine chemicals of high value. However, because of the complexity of lignite macromolecular structure, such fine chemical production encounters problems such as selectivity and separation, etc. The scientific understanding on the mechanisms of controlling the product distribution of tar and reaction pathways has not yet been achieved. On the basis of our previous research about microwave heat treatment for lignite, the production of coal-base monocyclic aromatic fine chemicals using microwave catalytic pyrolysis technology will be systematically studied. Self-developed absorbent/catalysts which are activated char impregnated with multiple transition metal combined with home-made microwave catalytic pyrolysis device and microwave thermogravimetric analysis device to analysis of macro dynamic characteristics of lignite microwave pyrolysis. In this proposal, the following aspects will be investigated, study of the responding mechanism of the lignite chemical structures and function groups to absorbent and catalysts, study of the effect of coalification degree, coal macerals and mineral in coal, systematically study of catalytic reaction mechanism and the composition distribution regulation mechanism of tar during the process of lignite microwave catalysis pyrolysis. The findings will provide the theoretical foundation to using low rank coal to produce high value-added monocyclic aromatic fine chemicals and high value utilization of lignite resources.

褐煤的分子结构中含有大量单环芳香结构单元，利用其自身分子结构的特点生产高附加值单环芳香类精细化学品可以促进我国褐煤资源的高值高效利用。但由于褐煤的大分子结构的复杂多样性，使目标化学品的选择性和分离均有极大难度，而面向精细化学品的焦油产物分布调控机制等科学问题目前尚不清晰。本项目在大量前期工作基础上，提出具有创新性的利用微波催化热解技术生产单环芳香精细化学品的技术路线。拟使用自主研发的多元过渡金属吸波/催化剂，利用自制的微波催化热解实验台架和微波热重分析实验台架，研究褐煤微波催化热解的断链机理和热解反应动力学，明晰微波催化热解过程中褐煤不同化学结构和化学官能团对微波的响应机制，系统研究褐煤微波催化热解过程中催化反应机制及面向单环芳香化合物的焦油产物分布的定向调控机制，为利用褐煤生产高附加值单环芳香精细化学品技术的研发提供可靠的理论依据。

褐煤的分子结构中含有大量单环芳香结构单元，利用其自身分子结构的特点生产高附加值单环芳香类精细化学品可以促进我国褐煤资源的高值高效利用。微波热解与常规加热相比具有更快的加热速率、更均匀的宏观温度场，从而有利于提高焦油总产率和调整焦油产物的分布。利用多种催化剂作为即可吸收微波又能提高目标产物产率和选择性的双功能催化剂，通过微波催化热解产生焦油、气体和半焦等产物，研究了双功能催化剂在褐煤低温催化热解过程中对酚类化合物及合成气的定向催化作用并分析其反应机理。本项目以褐煤和生物质为原料，研究了惰性吸波剂（碳化硅）、碳基吸波催化剂（活性炭、半焦及碳化硅+活性炭）、过渡金属吸波催化剂（Fe3O4、活性半焦负载钴和镍）等及不同热解温度（400℃、500℃、600℃、700℃）等条件对褐煤微波热解产物产率及组分分布的影响。通过反应器的改进，利用两段反应器深入研究了挥发分与半焦的交互作用，加深了微波催化对焦油制备苯酚、愈创木酚、多环芳烃等高附加值芳香产物及氢气和一氧化碳等合成气产物机理的研究；加深了褐煤和生物质在微波催化共热解条件下协同作用的机制；通过微波催化剂对焦油产物的分布进行有效调控，在使用半焦负载过渡金属催化剂条件下焦油产物中酚类等单环芳香化合物成为焦油中的主组分。通过褐煤微波热解可以获得具有较高市场价值的单环芳香化合物、多环芳香化合物及合成气等，为利用褐煤和生物质热解实现大规模制氢和生产高附加值芳香化合物的联产技术提供了理论基础和可行性，该技术在我国煤化工产业具有良好的工业推广前景。