5-羟甲基糠醛选择转化制可再生对二甲苯的多相催化研究

Efficient and target-specific conversion of 5-hydroxy- methylfurfural (HMF), an important renewable compound that has been identified as "a versatile intermediate linking carbohydrates and conventional petrochemical industry", into value-added compounds is of great significance for advanced biorefinery concepts based on platform chemicals. The primary objective of the current proposal is to explore and develop new advanced processes that can deliver selective catalytic conversion of HMF to produce para-xylene (PX) and investigate the relevant reaction mechanism and pathways. Focusing on the key processes including selective reduction of HMF to produce 2,5-dimethylfuran (DMF) and the subsequent Diels-Alder cycloaddition of ethylene to produce PX, special efforts will be dedicated to three aspects: investigating the catalytic behavior of the M/ZrO2 (M=Cu or Au) catalysts recently developed by our group for the selective reduction of HMF to DMF using bio-renewable formic acid as the convenient hydrogen source, finding high-performance catalysts for the Diels-Alder cycloaddition of DMF to ethylene to produce PX, and building bi-/multi-functional metal-solid acid composite catalytic systems for PX production directly using HMF as feedstock. Efforts will also be directed to gain insight into the influence of metal dispersion, metal-support interactions and surface acidity/basicity on the activity, selectivity and stability of the catalysts, understanding the mechanistic pathways involved in the relevant processes, exploiting the concepts of catalyst designing, seeking and fabricating highly efficient catalytic system for value-added utilization of HMF, thus providing guidance of theory and practice for developing new technologies for transformation of biomass to aromatics.

5-羟甲基糠醛(HMF)是一种重要的可再生平台分子，被认为是"联系碳水化合物与传统石化产业的桥梁化合物"，研究其高效转化利用对缓解资源紧缺危机和解决能源环境问题具有重要意义。本项目旨在研究和开发HMF催化选择转化制对二甲苯(PX)新工艺，并探究该过程机理和反应途径。针对所涉及的HMF选择还原制2,5-二甲基呋喃(DMF)及其后续DMF与乙烯环加成制PX等关键过程，研究本课题组近年发展的以甲酸作可再生氢源的HMF选择还原制DMF的催化活性/选择性变化规律；筛选和创制高性能乙烯环加成制PX催化剂；构建HMF为原料直接制PX的金属-固体酸双/多功能复合催化体系。系统认识载体表面酸碱性质、金属组分分散状态及其与载体相互作用与催化活性、选择性和稳定性的关系，明确相关过程选择转化作用机制，拓展催化剂设计理念，发现和创制HMF增值利用的高效催化体系，为发展相应生物质制芳烃新技术提供理论指导和科学基础。

本项目针对多相金属-固体酸双/多功能复合催化剂在催化5-羟甲基糠醛(HMF)选择转化制对二甲苯(PX)反应中金属-载体协同作用机制、性能设计及调控规律等关键问题开展了基础性研究工作。在相关固体酸材料负载高分散金属催化HMF选择还原制2,5-二甲基呋喃(DMF)及其后续DMF与乙烯环加成制PX等关键过程的反应机理、性能调控规律和相关高效多功能固体催化体系设计等方面进行了探索。针对HMF选择还原制DMF，发展了基于可再生甲酸（HCOOH）为氢源的高效氢解反应体系，可有效避免传统加氢面临的反应温度高、选择性低及产物损失严重等缺点。发展了氧化锆负载Au-Pd高效催化剂，通过金属与酸的功能匹配，实现了无外源H2气体条件下HMF一步转化为DMF，DMF收率高达98%。针对DMF与乙烯环加成/脱水成制PX反应，设计合成了高效铌氧化物（NbOx）功能化介孔氧化硅材料，酸性质及NbOx与 MCM-41等介孔氧化硅的协同作用可有效活化乙烯与DMF分子，加快反应速率，获得高达130 mmolPX(gcath)-1的初始反应速率，设计合成了基于四方相氧化锆（t-ZrO2）简单氧化物催化剂，通过调控相关氧化物的表面酸碱特性、结构组成和产物环加成/脱水路径分析，获得收率达到90%的PX产物，催化剂可多次连续使用不失活，具有较好的稳定性。针对多功能复合催化剂上HMF到PX的集成式转化，通过氧化锆稳定Au-Pd粒子的金属-固体酸双功能协同作用（金属中心的HMF选择还原，酸中心的DMF与乙烯环加成），实现了单个多功能固体催化剂上HMF到PX的简约集成式转化。在上述研究基础上，对该集成式HMF制PX反应过程进行了全面的技术经济分析与论证。