光催化重整生物质衍生多元醇制备附加值化学品的研究

Ployols derived from cellulose are sustainable feedstock to produce valuable chemicals and fuels. Traditionally, conversion of polyols by hydrogenolysis technology is one of the most important methods, in which polyols undergo the deoxygenation and sequent scissor of C-C bonds. However, the hydrogenolysis process of polyols on heterogeneous catalysts usually requires critical operating conditions and high energy consumption. Particularly, the consumed huge hydrogen derived from fossil fuels, impairs greatly the sustainability for the economical and environmental implementation of biomass conversion. Thereby, we propose to innovative strategy to perform the utilization of polyols, which can be converted to valuable chemicals by photocatalytic reforming based on semiconductors in water. The critical step in photocatalytic reforming of polyols is to couples the activation of water with the dehydrogenation of polyols. Polyols undergo the fracture of C-C bonds and are converted to unsaturated aldehydes and carboxylic acids under mild conditions, using photoexcited hole or indirectly activated oxygen species from water. Hydrogen is produced by photoexcited electron, which can be further used to hydrogenated of the above the products from polyols. The system only involves polyols and water.Light is the only driving force. Thereby, photocatalytic reforming of polyols is inherently green process and can prompt the sustainable utilization of biomass resource.

纤维素转化为多元醇平台分子，进一步通过这类平台分子制备化学品和燃料是生物质利用和转化的重要途径之一。传统上利用氢解技术进行 "加氢／脱氧"和C-C的断裂实现多元醇分子的衍生转化。但氢解方法需要苛刻的反应条件、高的能耗，尤其是耗费大量来自化石能源的氢气，严重阻碍了生物质资源的可持续开发和利用。本项目拟通过利用半导体光催化剂，耦合水的活化氧化过程，实现多元醇平台分子到高附加值化学品和燃料的重整过程。利用用光激发的空穴以及空穴活化的水氧化物种，温和条件下实现多元醇分子中C-C选择性断裂，制备不饱和醛和酸等化合物；利用光激发电子产生氢气，产生的氢气进一步可以还原氧化产物。整个反应过程只有多元醇和水参与反应，光作为反应的唯一驱动力，实现真正意义上的生物质的可持续利用。

纤维素转化为多元醇平台分子，进一步通过这类平台分子制备化学品和燃料是生物质利用和转化的重要途径之一。传统上利用氢解技术进行 “加氢／脱氧”和C-C的断裂.实现多元醇分子的衍生转化。但氢解方法需要苛刻的反应条件、高的能耗，尤其是耗费大量来自化石能源的氢气，严重阻碍了生物质资源的可持续开发和利用。本项目通过利用半导体光催化剂，耦合水的活化氧化过程，实现纤维素到高附加值化学品的重整过程。主要研究成果有以下几方面：1）利用水作为氧源，发现在光催化剂TiO2的金红石相以及BiVO4表面，水可以氧化成过氧物种，进而实现甘油，葡萄糖的选择性氧化；2）利用金属吸光的热效用和固体酸相耦合，利用光热效应实现了纤维素低温条件下的水解过程，高选择性得到葡萄糖和HMF；3）通过构建超薄的二维纳米片光催化剂Bi2MoO6,大幅度提高了光生电荷的分离效率，在芳香醇的氧化中表现出超高的活性和优异的选择性。总之，我们实现了纤维素大分子到多元醇平台分子，以及平台分子到高附件化学品的全过程绿色光催化转化过程。