纤维素高效转化制备化学品的催化基础

Non-edible cellulose is the most abundant biomass, and its transformation into fuels and chemicals is thus important for the development of renewable energy. This proposal aims at the highly efficient conversion of cellulose into some important chemicals. For this purpose, cellulose hydrolysis is a key step, which will be achieved under mild conditions on nano-sized solid acids with mimic enzyme functions and by reversible Bronsted acids –derived from recyclable metal salts. The glucose intermediate will then be instantaneously hydrogenated, dehydrated or hydrogenolyzed to form sorbitol, isosorbide, glycerol, propylene glycol and acetol on metal and metal oxide-based catalysts with well-defined structures and functions. Glycerol selective hydrogenolysis and oxidation to 1,3-propanediol and lactic acid, respectively, as well as acetol selective oxidation to pyruvic acid will be also examined. The catalyst structures and reaction mechanisms involved in this proposal will be studied by complimentary methods, such as Raman and XPS, and kinetic and isotopic scrambling techniques. Such studies, together with the DFT calculation, will lead to the deep insights at the molecular level into the relationship between the structure and functions of the catalysts and their catalytic performances, which will lay the scientific basis for the efficient utilization of cellulose and other kinds of biomass resources.

纤维素是自然界最丰富的生物质且不可食用，将其转化为燃料和化学品是发展可再生能源的一个重要方向。本项目将围绕纤维素高效转化为化学品，构筑纳米结构仿酶功能固体酸催化剂和能够产生可逆质子酸的固体金属盐体系，实现温和条件下纤维素的绿色高效水解；构筑具有特定结构与功能的分子筛、金属和金属氧化物催化剂，与纤维素水解步骤耦合，将生成的葡萄糖中间体高效加氢、脱水或选择断裂其C-C与C-O键，实现纤维素定向转化为山梨醇、异山梨醇、甘油、丙二醇、羟基丙酮等多元醇目标产物。揭示甘油特定C-O键活化机理，实现选择氢解合成1,3-丙二醇，实现甘油和羟基丙酮选择氧化合成1,3-丙二醇和乳酸等目标产物。利用Raman、XAFS等谱学、同位素标记和动力学等手段在接近反应条件下研究催化剂活性位结构和反应机理等，并结合理论计算，认识催化剂活性位结构、酸碱性等因素与其催化性能间的关系，为纤维素和其它生物质高效利用奠定科学基础。

纤维素是自然界最丰富的生物质且不可食用，将其转化为燃料和化学品是发展可再生能源的一个重要方向。如何实现纤维素的高效水解以及葡萄糖等中间体的选择性转化，是该项目重点解决的关键科学问题。制备了新型碳质磺酸型固体酸催化剂, 揭示了其在纤维素水解条件下失活的机理；揭示了固体酸与纤维素相互作用的机制；揭示了纤维素以及葡萄糖、山梨醇反应的路径，实现了纤维素的绿色高效水解，并与脱水、加氢等有效匹配，实现了纤维素定向转化合成C4化学品（比如：1-羟基-2-丁酮）等目标产物；实现了山梨醇、甘油等多元醇选择氢解合成丙二醇等目标产物，发展了葡萄糖二酸选择氢解合成1,6-己二酸新方法等。这些进展为纤维素以及其它种类生物质的高效转化制备化学品奠定了科学基础。