生物质基己二酸的绿色催化合成及催化剂构效关系的研究

The green catalytical synthesis of highly value-added adipic acid from biomass-derived platform chemicals is one of the important ways to high-value utilization of biomass. This application selects platinum group metals with high activity in hydrogenation of C=C bond and oxides of Ⅵ B group metals with high activity in hydrodeoxygenation of C-O bond as the main catalytic active components. And by optimized synthesis methods, bifunctional nanocatalysts with refined size and structure were prepared. Under the synergy effect of such functional components, biomass-derived 2,5-furandicarboxylic acid was converted to the target adipic acid with high activity and selectivity. The structure-activity relationship of the bifunctional catalysts in the conversion of 2,5-furandicarboxylic acid was revealed based on the study of the catalyst composition, microstructure and surface properties on the catalytic activity and selectivity. In order to elucidate the reaction pathway and the mechanism of the selective catalytic conversion of 2,5-furandicarboxylic acid, and establish effective ways to adjust the catalytic reaction pathway, the non-steady-state species and the surface adsorbed species were identified, and the catalytic active sites were characterized. Combination with the density functional theory calculations, the microscopic structure, benefit for the activation and conversion of 2,5-furandicarboxylic acid, was constructed, and the new and more effective catalyst systems were designed from the molecular / atomic level. These studies also provide theoretical basis for the construction of new catalysts for the hydrodeoxygenation and transformation of specific oxygen containing compounds.

通过生物质基平台分子选择催化制备高附加值的己二酸等化学品是生物质高值化利用中的一条重要途径。本申请以具有较高C=C双键加氢活性的Pt系贵金属和C-O键加氢脱氧活性的ⅥB组金属氧化物为主活性组分，采用优化的合成方法，制备尺寸和结构可控的纳米催化剂，在两种活性组分的协同作用下，将生物质基2,5-呋喃二甲酸高活性和高选择性地转化为目标产物己二酸。研究催化剂的组成、微观结构、表面性质等对催化剂活性和选择性的影响规律，揭示催化剂在2,5-呋喃二甲酸选择转化反应中的构效关系。借助对非稳态物种、表面吸附态物种的鉴别和对催化剂活性位的表征，认识2,5-呋喃二甲酸选择转化反应的路径和机理，初步建立调控催化反应路径的有效方法。结合密度泛函理论计算，构筑有利于2,5-呋喃二甲酸活化和转化的微观结构，从分子/原子水平上设计新的更有效的催化剂体系，同时也为针对特定含氧化合物加氢脱氧的新型催化剂的创制提供理论基础。

由可再生的生物质基原料，如2,5-呋喃二甲酸（FDCA）等，生产大宗化学品己二酸将为现代化工行业的可持续性发展提供一条新的路径。本项目开发了一种由TiO2分别负载的Pd与MoOx机械混合组成的Pd/TiO2+MoOx/TiO2催化剂，在水中高效稳定地实现了FDCA加氢脱氧至己二酸的催化转化，在473 K，2 MPa氢压的条件下，FDCA转化率达到100%，己二酸收率达到85.9%。反应过程中，FDCA中呋喃环上C=C双键首先被饱和加氢得到2,5-四氢呋喃二甲酸（THFDCA）中间产物，THFDCA进一步加氢脱氧得到C-O键断裂的初级产物2-羟基己二酸（2-HHDA）及次级产物己二酸。结合XRD、XPS及Raman等表征方法表明，在TiO2表面孤立分散的O=Mo(-O-)3物种是C-O键断裂过程中决速步的催化活性位，而Pd组分起到了促进催化循环中MoOx的还原及提供活性H原子的作用。通过核磁和DFT理论计算等方法证明，反应中间产物中α-C-H的活化是C-O键断裂的关键步骤，其中邻位羧基对α-C-H活化具有必要的促进作用。本项目创制了一条己二酸的绿色可再生的生产路径，揭示了催化剂在FDCA加氢脱氧反应中的构效关系和催化作用机理，同时为催化剂的改进和工艺的放大提供了理论基础。