Single atoms as highly selective active sites in heterogeneous catalysis

由于化石燃料储量的减少，从生物质生产燃料和化学品变得越来越重要。生物基工业的发展和可持续性将高度依赖于能够选择性地将功能化有机分子转化为化学中间体和商业产品的催化过程。在这方面，纤维素生物质是最丰富的生物质形式，也是世界上最重要的可再生能源之一。纤维素衍生的化学品如糠醛提供了非常重要的商业机会，因为它们可以用作合成各种产品的起始材料和结构单元。因此，开发廉价、环境友好的低温催化剂具有稳定和长期的性能，所描述的工作旨在开发用于一类氢化反应的原子效率催化剂，这类氢化反应是生物基能源和精细化学品工业的核心。将研究两种不同类型的材料，这两种材料都是基于氧化物载体表面或相对便宜的金属纳米颗粒表面上的少量孤立的催化活性金属中心金、钯和Pt的催化性能。将研究氢在孤立位点上的活化及其在氧化物载体上的溢出，以确定有前途的低温氢化系统。重点研究糠醛、肉桂醛和丙烯醛的选择性加氢反应。各种实验室和同步加速器为基础的技术将被用来建立分子结构和氢化活性和选择性之间的关系，对单原子网站。该项目开发的材料具有原子效率高和生产成本低的优点，因为只需要少量的贵金属。更重要的是，由于催化剂表面上活性中心的均匀性，单原子催化剂提供了对特定产物的改进的选择性。在氧化物载体上的精细分散体可以提供传统上使用的非均相氢化催化剂的相对便宜的替代物。

The production of fuels and chemicals from biomass becomes increasingly important due to the diminishing reserves of fossil fuels. The development and sustainability of bio-based industries will be highly dependent on catalytic processes capable of selectively transforming functionalised organic molecules to chemical intermediates and commercial products. In this respect, cellulosic biomass is the most abundant form of biomass and one of the most important renewable energy resources worldwide available. Cellulose derived chemicals like furfural offer very important commercial opportunities as they can be used as starting materials and building blocks to synthesize a variety of products. Therefore, there is a major industrial interest to develop cheap, environmentally friendly low temperature catalysts with stable and prolonged performance.The described work aims to develop atom efficient catalysts for a class of hydrogenation reactions that lie at the heart of the bio-based energy and fine chemicals industries. Two different classes of materials will be investigated both of which are based on the catalytic properties of small quantities of isolated catalytically active metal centres of gold, palladium and Pt on the surface of oxide supports or on the surface of relatively inexpensive metal nanoparticles. The activation of hydrogen on isolated sites and its spillover on the oxide support will be investigated in order to identify promising systems for low temperature hydrogenations. The reactions of principal focus will be the selective hydrogenation of furfural, cinnamaldehyde and acrolein. A variety of laboratory and synchrotron based techniques will be used to establish a relationship between molecular structure and hydrogenation activity and selectivity on single atom sites. The materials developed in this project offer the benefit of atom efficiency and low cost of production as only small amounts of precious metals are required. More importantly single atom catalysts offer improved selectivity towards specific products due to the homogeneity of the active center on the catalyst surface. Fine dispersions on oxide supports can provide a relatively cheap alternative to traditionally employed heterogeneous hydrogenation catalysts.