金属盐辅助酸强化碳水化合物醇解选择性合成的调控机制研究

A variety of high value-added chemicals and liquid fuel are accessible by the acid-catalyzed alcoholysis of carbohydrates. However, side reactions on sugar-based carbonization and inter-molecular dehydration of alcohol medium are the common situations, which affect the generation of target products and practical application of this technology. Metal salts, included a wide range of items and quite different characteristics, are useful alternative for building given effective catalyst system to solve the above-mentioned issues. In light of the previous developed extremely low sulfuric acid catalyst system, our group preliminary finds tend to suggest that metal salts assisted (e.g., sodium sulfate, aluminum sulfate) benefit the selective synthesis of products. In this project, catalytic performances on alkali metal salts and group III A metal salts as well as their compound salts assisted extremely low sulfuric acid catalyzed alcoholysis of carbohydrates in methanol medium will be investigated to reveal their effect rules and leading factor for the generation of some special effect. Then, metal salts assisted acid catalyst system and regulation pathway for strengthening alcoholysis of carbohydrates (especially cellulose) will be structured mainly for the selective synthesis of methyl glucoside and methyl levulinate. Finally, its mechanism of action about leading selective processed of reaction will be discussed. The research of this project will not only establishes the important fundamental support for the practical application regarding selective synthesis of high value-added chemicals from carbohydrates alcoholysis, but also provides some theoretical guidance to construction of specific effective catalyst system in the chemical transformation of biomass.

酸催化醇解碳水化合物可制取多种高附加值化学品和液态燃料，但常面临糖基炭化和体系醇自身缩合脱水副反应影响目标产物生成及其实际应用。金属盐种类繁多，性质各异，是构建特定有效催化体系解决上述问题的有益选择。结合前期开发的超低硫酸催化体系，申请人课题组初步研究表明硫酸钠、硫酸铝等辅助有益于选择性进行醇解。在此基础上，本项目研究含碱金属、第三主族金属的不同阴离子盐和以上两者复合辅助超低硫酸在甲醇体系中催化醇解碳水化合物的反应情况，揭示其作用规律及产生特定效果的主导因素；着重构建强化碳水化合物（尤其是纤维素）醇解高选择性分别合成甲基葡萄糖苷和乙酰丙酸甲酯的金属盐辅助酸催化体系及调控途径；探讨特定有效金属盐辅助酸强化碳水化合物醇解和主导反应选择性的作用机制。预期研究成果可为碳水化合物选择性醇解合成高附加值化学品的实际应用提供重要基础支撑，也为生物质化学转化中特定有效催化体系的构建提供理论参考。

生物质是唯一含碳的可再生资源，是替代不可再生化石资源生产液体燃料和化学品的重要选择。酸催化醇解生物质基碳水化合物可制取多种高值化学品和液态燃料，清洁、高效、高选择性和低成本的催化体系构建被认为是该途径实际应用面临的关键性挑战。金属盐种类繁多，性质多异，是构建特定有效催化体系满足上述要求的有益选择。本项目研究了含碱金属、第三主族金属的不同阴离子盐辅助超低硫酸在醇体系中催化醇解碳水化合物的反应情况，揭示了金属盐协同的作用规律；构建起了碱金属盐协同超低硫酸强化碳水化合物醇解选择性合成烷基葡萄糖苷，三氟甲磺酸铝协同超低硫酸强化纤维素和木质纤维生物质高选择性合成乙酰丙酸酯，路易斯酸金属盐氯化铝和氯化铬催化转化葡萄糖合成5-乙氧基甲基糠醛，路易斯酸金属盐氯化铝和氯化铜高效催化糖基衍生物糠醇选择性合成乙酰丙酸酯的催化体系及调控途径；揭示了以上特定有效金属盐辅助酸强化碳水化合物醇解和主导反应选择性合成目标高值化学品的作用机制。研究成果可为生物质基碳水化合物选择性醇解合成高值化学品的实际应用提供重要基础支撑，也为生物质化学转化中特定有效催化体系的构建提供有益理论参考。