糖类多羟基化合物选择酯化结构修饰催化剂的研究

Selective esterification of the hydroxyl groups in saccharides is not only the key for the production of sugar esters, but also is of great importance in transformation of bio-based saccharides to high-value chemicals. This project is to develop a series of structure-modified molecular-sieve catalysts for efficiently selective esterification of saccharides within their confined pores. In order to achieve the selective esterification of the hydroxyl groups in saccharides, the saccharides will be designed to esterify with fatty acid within confined pore channels and the produced monoesters will be limited further reaction to sugar diesters by a narrow pore size. In which, we plan to modify the acidity of the catalyst by doping and surface-modification, and synchronously adjust the pore structure to match the size of sugar monoester. Using the esterification of sucrose and palmitic acid as a model reaction, we plan to study the relationship between the structure of the molecular sieves and the selective esterification of sucrose. We will further study the selective esterification of other mono-, di-, tri-, saccharides. We plan to use several characterization methods, such as HPLC, HPLC-MS, NMR, TEM, SEM, physisorption, chemisorption, Py-adsorbed FT-IR. We will further study the interaction between the active sites in the catalysts and the hydroxyl groups in saccharides by using in-situ NMR, in-situ FT-IR. To the end of this project, we want to develop highly efficient structure-modified molecular sieves for selective esterification of saccharides, and also provide theoretical and scientific basis for the general law of hydroxyl group activation in saccharides.

糖类多羟基化合物的选择酯化不仅是生产糖基脂肪酸酯化学品的核心，而且对糖基生物质高值化利用至关重要。本项目拟开发局域催化糖类化合物选择酯化的策略，构建结构修饰的分子筛催化剂，通过骨架掺杂或表面修饰，调节分子筛酸中心强度和总量，通过修饰活性中心周围孔道结构，增强糖类羟基酯化活性的同时，限制单酯产物与活性中心再接触，达到对单酯的选择筛分，实现糖类多羟基化合物的催化选择酯化。以蔗糖与棕榈酸酯化反应为模型反应，采用液相色谱、质谱、核磁等检测手段，电子显微学技术和物理、化学吸附、吡啶吸附-FTIR等表征手段，探索催化剂结构和糖类化合物选择酯化之间的规律，并拓展催化体系至其他单糖、二糖、三糖基脂肪酸单酯的选择性合成。通过原位核磁、红外等检测手段对反应机制进行研究，探索糖类羟基与催化剂活性中心相互作用机制，为糖类化合物羟基选择活化的共性规律提供理论和科学依据。

糖类多羟基化合物的选择酯化不仅是生成糖基脂肪酸酯化学品的核心，而且对糖基生物质高值利用至关重要。本项目围绕生物表面活性剂糖酯的选择合成，主要开展了蔗糖脂肪酸酯标准品合成及其定量分析、有机碱修饰氧化硅纳米球的控制制备及其催化蔗糖选择酯化、机械强化无溶剂法合成公斤级蔗糖酯等研究：建立了快速准确的蔗糖脂肪酸酯HPLC-ELSD分析方法，18 min内实现蔗糖酯的定量分析。开发了有机碱修饰分子筛催化选择合成蔗糖脂肪酸单酯的策略，单酯选择性＞95%，收率＞50%；研究表明，TBD/MSN碱性和孔径是影响蔗糖脂肪酸单酯选择性和收率的重要因素，当孔径与单酯分子尺寸相近时，单酯收率增加，且二酯生成受限，当孔径大于二酯分子尺寸时，对单酯不具备选择性，分析认为，蔗糖与脂肪酸酯的酯交换反应主要发生在孔道内，且先形成单酯，而后单酯反应再形成二酯。研发了机械强化无溶剂法合成高品质蔗糖脂肪酸酯技术，并完成公斤级放大合成和企业应用评价，正寻求中试合作。共发表论文4篇（SCI论文2篇），申请发明专利5件（已授权2件），参与撰写英文著作《Biobased Surfactants: Synthesis, Properties, and Applications, Second Edition》1章节，获中国发明协会“发明创业奖·项目奖”1项；获广东省科学院百名青年人才培养专项1项《糖酯类生物功能分子的控制合成及应用研究》（2019GDASYL-0104023，2019.01-2021.12）”。本项目研究工作为糖类多羟基化合物选择酯化提供一种多相催化方法和催化材料，为认识糖类多羟基化合物与脂肪酸酯在有机碱修饰分子筛孔道内的催化酯交换反应过程提供共性规律和理论依据，亦开发了具有自主知识产权的蔗糖酯合成技术，为国内开发高品质蔗糖酯生成制造和日化、医药等高端应用提供技术保障。