Designer Carbon Nanotube Columns for Chemo- and Bio-Catalytic Synthesis in Flow

氢化反应涉及在双键上添加氢气，占所有工业化学步骤的10-20%。然而，工业氢化方法通常依赖于可能污染最终反应产物的贵金属、重金属。选择性也是金属催化剂的一个重大挑战：氢化可能发生在复杂分子上不需要的位置，分子上的某些取代基如卤素可能在氢化过程中丢失，并且在金属催化剂氢化过程中很难产生手性（镜像）分子的单一对映异构体形式。与此相反，从天然生物中分离的酶非常擅长以精确的选择性获得这些相同的化学产品，并且由于它们是从易于培养的微生物细胞中分离出来的，因此是完全可生物降解和可再生的。不幸的是，目前应用酶（生物催化剂）制备氢化化学产品的方法产生大量化学废物，这使得该方法不那么有吸引力并且成本更高。这是因为酶需要昂贵的辅因子，在反应过程中必须不断地补充辅因子。辅因子再充电过程通常由糖（葡萄糖）提供动力，并且大多数葡萄糖分子被浪费，并且可能在反应结束时被燃烧。为了清理生物催化，Vincent小组开发了使用氢气驱动辅因子再充电的生物催化策略，或完全避免对辅因子的需要。本研究的关键主题是使用氢化酶选择性地氧化二氢，和使用碳支持材料的氢化酶固定。该项目位于生物催化和材料科学的交界处，重点研究用于支持生物催化剂生成胺产品的碳材料的基本设计原理。胺是由NH 2官能团定义的化合物，在制药、染料和塑料生产中具有巨大的工业重要性，需要大规模生产。本文介绍的项目将探索各种设计碳材料支持氢化酶和参与胺化学产品选择性生成的能力。一个重点将放在碳纳米管，这是越来越感兴趣的科学界，因为他们的可调的电子和化学性质，并将提供一个平台，研究基本材料性能和催化效率之间的关系。通过优化和放大这种生物催化加氢系统，可以开发出一种更绿色，选择性和商业可行的方法来产生重要的胺化合物，在研究，工业和污染物修复中具有广泛的应用。该项目福尔斯EPSRC物理科学-催化研究领域。

Hydrogenation reactions involve addition of hydrogen gas across a double bond, and account for 10-20% of all industrial chemical steps. However, industrial hydrogenation processes often rely upon precious, heavy metals which may contaminate the final reaction product. Selectivity is also a significant challenge with metal catalysts: hydrogenation may occur in unwanted positions on a complex molecule, certain substituents on the molecule such as halogens may be lost during hydrogenation, and it is very difficult to produce single enantiomer forms of chiral (mirror image) molecules during hydrogenation with metal catalysts. In contrast, enzymes isolated from natural organisms are very good at achieving these same chemical products with exquisite selectivity, and are fully biodegradable and renewable because they are isolated from cells of micro-organisms which are easy to cultivate.Unfortunately, current methods for applying enzymes (biocatalysts) to make hydrogenated chemical products generate a lot of chemical waste which makes the processes less attractive and more costly. This is because the enzymes need expensive cofactors which must be re- charged continually during a reaction. The cofactor re-charging processes are usually powered by sugar (glucose), and most of the glucose molecule goes to waste, and may be burnt at the end of the reaction. To clean up biocatalysis, the Vincent group have developed biocatalytic strategies for driving cofactor re-charging using hydrogen gas, or avoiding the need for cofactors completely. Key themes of this research are the use of hydrogenase enzymes to oxidise dihydrogen selectively, and the use of carbon support materials for hydrogenase immobilisation. This project lies at the interface between Biocatalysis and Materials Science, and focusses on fundamental design principles for carbon materials which are suited to supporting biocatalysts for the generation of amine products.Amines are chemical compounds defined by the presence of an NH2 functional group and are of immense industrial importance in the production of pharmaceuticals, dyes, and plastics, necessitating their production on a massive scale. The project presented herein will probe various designer carbon materials for their ability to support hydrogenases and participate in the selective generation of amine chemical products. A focus will be placed on carbon nanotubes, which are of increasing interest to the scientific community because of their tuneable electronic and chemical properties and will provide a platform for investigating the relationship between fundamental material properties and catalytic efficiency. Through optimisation and scale-up of this biocatalytic hydrogenation system, a greener, selective, and commercially feasible method for generating important amine compounds could be developed, with wide applications in research, industry, and pollutant remediation.This project falls within the EPSRC Physical Sciences - Catalysis Research Area.