氮掺杂碳材料键合金属卟啉复合光催化剂构筑及其催化氧化葡萄糖合成葡萄糖二酸的研究

Glucaric acid as one of the oxidation products of glucose is considered to be one of the most important biomass-based products. Due to the difficulty in the oxidation of glucose into glucaric acid, how to improve this reaction with high selectivity and conversion is a tough problem in scientific fields. In this project, nitrogen-doped carbon materials will be prepared by thermal carbonization of the nitrogen-containing biomass, followed by the binding of metalloporphyrin on its surface through coordination bonding to produce the photocatalysts. The photocatalytic oxidation of glucose into glucaric acid will then be carried out by the use of the as-prepared nitrogen-doped material immobilized metalloporphyrin as the photocatalysts. The axial coordination of the nitrogen with the metal cations in metalloporphyrin will not only greatly promote electron transfer, resulting in the improvements of its photocatalytic activity, but also enhance the stability of the photocatalytic materials. The photocatalytic performance of the photocatalytic materials can be adjusted by the modification of the structure of nitrogen-doped carbon material, the central metals of metalloporphyrin and the peripheral groups of metalloporphyrin. With the adjustments of the catalyst structure together with the optimization of photocatalytic reaction parameters, this method will hopefully realize the photocatalytic oxidation of glucose into glucaric acid with high conversion and selectivity. Furthermore, the reaction intermediates of the photocatalytic oxidation of glucose into glucaric acid will be identified by the application of spectroscopies and isotope labeling technologies, and a proper mechanism and kinetic equations will be proposed. With the studies in this project, a promising new method will be developed for the catalytic conversion of biomass into valuable chemicals, which are believed to make large contributions to industrial applications and further scientific research in the near future.

催化葡萄糖氧化合成葡萄糖二酸是生物质转化利用的重要研究方向之一。本项目拟构建一类氮掺杂碳材料键合金属卟啉类化合物的复合光催化剂，用于光催化氧化葡萄糖选择性可控合成葡萄糖二酸。拟在惰性气氛下直接热解含氮生物质资源制备氮掺杂碳材料，进一步通过配位键在氮掺杂碳材料表面键合金属卟啉类化合物，构建一类基于非贵金属且性能稳定的新型复合光催化剂。该材料表面氮元素与卟啉类化合物的中心金属离子轴向配位，更有利于电子传递，提高光催化材料活性。以该光催化材料进行葡萄糖光催化氧化为葡萄糖二酸研究。通过调变光催化材料的结构和优化光催化氧化反应工艺条件，最终实现葡萄糖光催化氧化为葡萄糖二酸的高转化率、高选择性。运用同位素示踪技术和谱学手段探究反应过程的中间体，测定反应过程各物质含量变化，构建动力学方程，阐明反应机理。本项目研究将为生物质绿色催化转化制备重要化学品提供新的研究思路，具有重要的应用前景和科学价值。

本项目采用浸渍法将含硫氮杂金属卟啉与氮掺杂碳材料、金属氧化物或分子筛复合构建了系列高效的复合型金属卟啉类化合物光催化剂，研究了金属卟啉与载体之间的协同效应及其光生电荷分离效率的增强机理。在水体系和以过氧化氢或空气中的氧气为氧化剂、常温常压的条件下研究了复合光催化剂光催化氧化葡萄糖的性能。通过调控复合催化剂的结构，改变活性物种的类型及数量，以及改变葡萄糖及其氧化产物在催化剂表面上的吸附行为，获得高选择性的氧化产物。利用SnO2-OVs/CoPz复合光催化剂，实现了在水溶液中葡萄糖的氧化，葡萄糖的转化率为43.6%，三种氧化产物有机酸（葡萄糖二酸、葡萄糖酸和甲酸）的总选择性达到81.5%，其中葡萄糖二酸的选择性达到28.5%。根据已发表的相关文献分析，在水溶液中，以空气中的氧气为氧化剂，我们的绿色催化氧化葡萄糖生成葡萄糖二酸的选择性，应该说是最好的结果之一。本项目研究将为生物质通过在水溶液中光催化转化合成高附加值化学品提供重要的研究思路。