热解耦合光催化定向转化工业木质素制备轻质芳烃

Concerning on the characteristic of being regenerable organic carbon resources is a strategic direction of biomass energy development. The study on the high-valued utilization of industrial lignin (IL) regard to the preparation of light aromatic hydrocarbons (BTX) has been intensively investigated in recent years. The catalytic pyrolysis technique is preferred to the conversion of IL to BTX by researchers, and the industrial application of the biomass-based BTX production is mainly limited by the following problems: 1) the low yields of BTX; 2) the low selectivity of benzene, toluene, and xylene; 3) the deactivation of the traditional catalyst (HZSM-5). To overcome this, the catalytic pyrolysis coupled with photocatalytic technology is proposed in this project. With the purpose of improving the stable yield and selectivity of the BTX, the bio-based catalysts with high catalytic performance and stability and modified carbon nitride materials will be designed. Series of testing instruments will be initially employed to study the characteristics of products distribution during IL pyrolysis and the mechanism of controllable release of small hydrocarbon free radicals by photocatalysis with hydrogen donor. Thereby, the mechanism of the mixed phenols react with hydrocarbon free radicals and the regulation of benzene, toluene and xylene, will be revealed by a photocatalytic reactor-large scale thermogravimetry-FTIR joint test system. Synchronously, a novel bio-based catalyst with special pore structures for pyrolysis and modified g-C3N4 materials for photocatalysis will be rational synthetized, following by studying works on the synthesis-structure-performance of the bio-based catalyst for optimizing the BTX yield. This project will not only construct a new method for preparing BTX by pyrolysis-photocatalysis technology, but also provide the theoretical foundation for the large-scale application of industrial lignin.

关注可再生的有机碳资源属性是生物质能发展的战略性方向。制备轻质芳烃(BTX)是工业木质素(IL)高值利用的研究热点，前人研究主要采用催化热解手段，制备过程存在收率和选择性低，HZSM-5易失活等科学难题，困扰着IL制备BTX的规模化应用。为突破上述瓶颈，本课题拟采用热解耦合光催化技术，通过制备高效的炭基催化剂和氮化碳材料，达到稳定提高BTX收率及选择性的目的。首先采用系列测试仪器，深入研究IL热解产物特性及供氢剂光催化可控释放小分子碳氢自由基的机理；然后利用光催化反应器-“固定床热重”装置-FTIR联用系统，揭示混酚/碳氢自由基制备BTX的机理及B、T、X选择性的调控机制；同时制备微-介孔炭基催化剂和改性g-C3N4材料，通过催化剂制备-结构-性能研究，进一步提高BTX收率。本课题将建立IL催化热解-供氢剂光催化可控制备BTX的新方法和理论体系，为其规模化应用提供理论支持。

国家双碳战略目标对能源结构转型提出了更高的要求，针对我国能源现状，开发生物质基芳烃生产路线，是后石油化工时代的必然选择之一。本项目围绕生物质制备轻质芳烃的收率和催化剂易失活的问题，开展了生物质/工业木质素热解耦合光催化重整制备轻质芳烃的研究工作。系统研究了工业木质素等生物质的热解反应，明确了供氢剂自由基产生的特性与机理，揭示了碳氢自由基与酚类的取代反应是热转化过程中轻质芳烃生成的重要来源；从原料组成、光催化/热解催化剂设计角度，研究了生物质基轻质芳烃生成的协同反应机理，形成了4条生物质制备轻质芳烃的协同路线，明确了轻质芳烃收率的调控机制，阐明了酚类/小分子碳氢自由基制备轻质芳烃的反应机理与调控规律；阐明了生物质热解半焦在水蒸气和二氧化碳工业氛围下的交互反应机制，明确了生物质半焦孔隙结构的调控机制，定向制备了适用于轻质芳烃生成的0.55~0.56nm微孔的生物炭基催化剂载体，优化了活性组分和负载条件，深入研究了炭基催化剂制备-结构-性能的构效关系；以系统动力学研究为基础，自行设计加工了木质素及生物质热解-光催化重整多室分区反应器，开展了木质素及生物质制备轻质芳烃的实验室规模实验工作，打通了生物质0.8kg/h半连续热解-光催化重整制备轻质芳烃反应工艺路线并进行了适度优化，建立了生物质/木质素催化热解-光催化重整可控制备轻质芳烃的新方法和理论体系，为后续放大研究提供了坚实的基础。. 项目取得了生物质基芳烃最高芳烃收率6.38wt.%，最高相对含量77%，最高甲苯选择性90%，研究水平处于国内领先阶段，但离欧美国际先进水平尚存差距，下一步仍需在催化材料和反应器匹配上继续开展研究工作。围绕项目研究内容，共发表SCI收录论文10篇，申请中国发明专利2项；项目负责人常国璋入选宁夏自治区第四批青年人才托举工程。.