Investigating and exploiting surface cooperativity in multifunctional solid catalysts for carbohydrates reactions

多功能多相催化剂，特别是酸和碱催化剂，在开发从富含碳水化合物的不可食用生物质中生产有价值化学品的可持续途径方面发挥着关键作用，这被认为是替代日益减少的化石资源的一种有希望的选择。然而，碳水化合物的特性及其反应的复杂性给高效催化剂的开发带来了挑战。利用多功能材料不同表面组分之间的协同作用，类似于在酶中遇到的，是制备改进的多相催化剂的合适策略。然而，关于固体催化剂不同表面组分在碳水化合物反应中的作用的详细研究，可能导致合作物的识别和随后的开发，很少。本课题拟开展的工作是研究表面协同性对葡萄糖转化为5-羟甲基糠醛（HMF）的活性和选择性的影响。HMF是合成聚合物、精细化学品、燃料等的重要中间体，可以通过葡萄糖脱水以极低的产率生产，也可以通过葡萄糖异构化成果糖并将果糖脱水成HMF。后一种转化很难完成，需要含有Brønsted酸位（脱水）和Lewis酸或Brønsted碱位（异构化）的多功能固体。拟议的工作包括三项主要任务。任务一是制备由金属氧化物和带有有机官能团的金属氧化物组成的多功能催化剂。固体将包含具有促进本文所研究的催化反应和/或协同催化潜力的成分，例如锡，钛和钨的氧化物，以及磺酸，羧酸，羟基，硫醇和胺的功能。任务2是多功能固体的化学和物理表征，特别关注表面性质，通过使用各种各样的技术，并将包括详细的FT-IR和UV-vis-NIR研究。任务3是评价所制备的催化剂对葡萄糖-果糖异构化反应、果糖脱水成HMF或串联异构-脱水转化的催化性能。材料将被合成和修改为特定的催化实验，旨在评估固体的每个表面组分的作用和催化协同性的鉴定。这项工作的最终目的是为本文研究的反应和其他涉及碳水化合物的转化开发有效的催化剂。

Multifunctional heterogeneous catalysts, particularly acid and base catalysts, play a key role in the development of sustainable routes for the production of valuable chemicals from non-edible carbohydrate-enriched biomass, which is considered a promising alternative to the diminishing fossil resources. However, the characteristics of carbohydrates and the complexity of their reactions create challenges to the development of efficient catalysts. The exploitation of cooperation between different surface components of multifunctional materials, similar to that encountered in enzymes, is a suitable strategy for preparing improved heterogeneous catalysts. Nevertheless, detailed studies on the role of different surface components of solid catalysts in the reactions of carbohydrates, which could lead to the identification and subsequent exploitation of cooperations, are scarce. The work proposed in this project is the study of surface cooperativity on the activity and selectivity of multifunctional catalysts on the conversion of glucose into 5-hydroxymethylfurfural (HMF). HMF is an important intermediate in the synthesis of polymers, fine chemicals, fuels, etc., and can be produced by dehydration of glucose with very low yields, or through the isomerization of glucose to fructose in tandem with the dehydration of fructose to HMF. The latter transformation is difficult to accomplish and requires a multifunctional solid comprising Brønsted acid sites (dehydration) together with Lewis acid or Brønsted basic sites (isomerization). The proposed work comprises three main tasks. Task 1 is the preparation of multifunctional catalysts consisting of metal oxides and metal oxides functionalized with organic groups. The solids will contain components with potential for promoting the catalytic reactions investigated here and/or potential for cooperative catalysis, such as tin, titanium and tungsten oxides, and sulfonic acid, carboxylic acid, hydroxyl, thiol and amine functionalities. Task 2 is the chemical and physical characterization of the multifunctional solids, with special focus on the surface properties, by using a wide variety of techniques, and will include detailed FT-IR and UV-vis-NIR studies. Task 3 is the evaluation of the catalytic performance of the prepared catalysts on the isomerization reaction of glucose to fructose, dehydration of fructose into HMF or tandem isomerization-dehydration transformation. Materials will be synthesized and modified for specific catalytic experiments aimed at assessing the role of each surface component of the solids and for the identification of catalytic cooperativity. The ultimate objective of the work is the development efficient catalysts for the reactions investigated here, and for other transformations involving carbohydrates.