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，在开发利用非食用碳水化合物丰富的生物质生产有价值的化学品的可持续路线方面发挥了关键作用，生物质被认为是替代日益枯竭的化石资源的一种有前途的选择。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。开发多功能材料不同表面组分之间的协同作用，类似于酶的作用，是制备改进的多相催化剂的一种合适的策略。然而，关于固体催化剂不同表面成分在碳水化合物反应中的作用的详细研究很少，这可能导致识别和随后开发合作。本项目的工作是研究多功能催化剂对葡萄糖转化为5-羟甲基呋喃甲醛(HMF)的活性和选择性的表面协同性。HMF是合成聚合物、精细化学品、燃料等的重要中间体，可通过低产率的葡萄糖脱水或通过葡萄糖异构化生成果糖并同时将果糖脱水生成HMF来生产。后一种转变很难实现，需要一种多功能固体，该固体由布朗斯特酸中心(脱水)和路易斯酸或布朗斯特碱性中心组成(异构化)。拟议的工作包括三项主要任务。任务1是制备由金属氧化物和带有有机基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研究的催化反应的潜力和/或合作催化的潜力的成分，如锡、钛和钨氧化物，以及磺酸、羧酸、羟基、硫醇和胺功能。任务2是通过使用各种技术对多功能固体的化学和物理表征，特别是表面性质的表征，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异构化为果糖、果糖脱水为HMF或串联异构化-脱水转化的催化性能。将对材料进行合成和改性，以进行特定的催化实验，目的是评估固体的每个表面成分的作用并确定催化协同性。这项工作的最终目标是开发用于这里所研究的反应和涉及碳水化合物的其他转化的高效催化剂。

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.