Single atoms as highly selective active sites in heterogeneous catalysis

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.

The proposal aims to develop new materials for chemical transformations of interest to the bio-based energy and pharmaceutical industries by delivering new knowledge about selective heterogeneous hydrogenation processes through the development of better, more selective, cheaper and environmentally friendly catalysts. This will be achieved by studying: the formation of single atomic entities on metal nanoparticles and oxide supports; the selective hydrogenation of bio-derived molecules under a variety of conditions; the mechanistic aspects of hydrogen activation and spillover on these materials. In this respect the proposed work has the potential of important social and economic impact to the following sectors:

1. Industry: The principal industrial beneficiaries of this work are catalyst, fine chemicals and bulk chemicals manufacturers. The proposed research work will open the door to collaborative projects between academia and UK companies including precious metal catalyst and process chemicals manufacturers (including companies such as Johnson Matthey, GSK and BP). Companies interested in the proposed work will be approached directly by the PI and through well-established mechanisms in the University of Hull.

2. General Public: Improved heterogeneously catalyzed processes have the potential to impact the UK national economy and the financial market as they enable cheaper and faster large scale production of products through accurate processes with minimum impact to the environment. The project aims to deliver atom efficient green catalysts to synthesize a variety of products useful in diverse market segments. The local communities and schools will be informed about mitigation of environmental damage through efficient process design via the dissemination methods described in the "pathways to impact" document.

3. Academic community: The continuously increasing importance for environmentally friendly and cost effective processes for the production of chemicals has a large impact in catalysis research. The described experiments will be of interest to the UK and international catalysis community. It will also provide new knowledge on materials synthesis, alloy compounds, hydrogen capture and storage and it will be of interest to other sections of the academic community including materials science, physics and chemical engineering. The proposed work will enable the PI to establish a new research group in the area of heterogeneous catalysis and facilitate academic collaborations at the national and international level.