Nano-Integration of Metal-Organic Frameworks and Catalysis for the Uptake and Utilisation of CO2

Carbon dioxide levels have risen steadily with the combustion of fossil fuels and additional positive feedback effects due to natural CO2 sources. Recycling of CO2 driven by solar/renewable energy is an effective approach to address the problem. In a recent edition of Science (25th Sept 2009) entirely dedicated to this problem the opportunities and potential benefits arising form CO2 uptake from the open air (as opposed to capture during production) have been highlighted. The urgent need for capture and utilisation of CO2 is self-evident. Research in CO2 capture and in CO2 utilisation is currently based on a range of separate technologies and often ineffective e.g. for amine or alkaline sequestration. By combining ( nano-integrating ) capture and utilisation into a single continuous process the efficiency can be improved and at the same time the energy required to drive CO2 reduction is minimised. This project focuses on one-step CO2 capture and utilisation by linking catalysts directly with a novel CO2 absorber. Nano-scale-integration of CO2 uptake and utilisation processes will provide new highly efficient single-step processes to turn CO2 into useful products (polymers, carbohydrates, fuels). The main vision for this project is the idea of a catalyst nanostructure embedded into/immobilised onto a CO2 supplying membrane (Metal-Organic-Framework, MOF) substrate so that enhanced localised diffusion can deliver a high rate of CO2 into the active catalyst site.Metal Organic Frameworks (MOFs) have emerged as a front-runner for the uptake and storage of CO2 but have never been employed to support catalysts. Effective catalysts for the conversion of CO2 into useful chemical products have been discovered but usually require high concentration industrial CO2. In this project two areas of existing strength in the South-West, CO2 absorption and catalytic utilisation, are combined to provide new nano-structured functional catalyst membranes tailored to both capture and concentrate CO2 from the free atmosphere and convert it into useful products in a single continuous process. The developed technology based on functionalised and specifically tailored MOF-membranes will be entirely new. The catalytic processes will be driven by solar energy (photo- or bio-catalysis), renewable energy, or waste heat from carbon creating processes. Nanotechnology is integral to this project. Metal organic frameworks (MOFs) are promising materials for the specific absorption and storage of high concentrations of CO2. In a new approach the MOFs will be made into nanostructured membranes, which will concentrate CO2 from the atmosphere and feed it directly into a nanostructured catalyst layer. As the CO2 is reduced, fresh CO2 will be continuously drawn in with the catalyst located in the diffusion layer (with effective hemi-spherical diffusion of CO2 to the nano-catalyst). Three types of catalysis will be investigated for CO2 reduction: (i) direct gas phase reduction of CO2 to CO using a nanostructured catalyst and integrated MOF/catalyst materials for one step carbon capture and utilisation, (ii) CO2 will be electro-reduced on platinum or copper nanoparticles (or similar nano-structured catalysts) to form ethylene and higher hydrocarbons with nanostructured catalysts increasing the selectivity of process, (iii) bio-films of cyanobacteria will be used to fix CO2 from the MOF under illumination in a MFC setup. Nanostructuring of the conducting MOF surface with the biofilm attached is extremely important for good bacterial adhesion and function.Stages of effective modules (e.g. producing ethylene and producing CO) will be combined into reactors to deliver products of higher value (e.g. polymers, solvents, or fuels) in the second stage of the project. Parts and the overall process will be carefully assessed by life-cycle analysis and the desired end product will be a carbon negative process .

This project will help developing CO2 capture and utilisation technology designed to operate in open air. This kind of process suffers from the problem of dilution of CO2 in air (ca. 0.04%) but it benefits from potentially lower bulk operating costs when installed in suitable spaces and the ability to counter-balance the effects of mobile emitters such as cars and aircraft (see D.W. Keith, Science, 2009, 325, 1654). The process when sufficiently cheap and effective could be operated dispersed in smaller units or concentrated at a site of solar energy availability. With these boundary conditions set, the following impact scenarios are feasible: Impact on society: any contribution to CO2-lowering technology will reap future economic benefits in terms of carbon credits and a bonus in providing alternatives to large scale and potentially harmful geo-engineering solutions (e.g. ocean fertilisation). In addition to providing (i) technical development and (ii) fundamental insights into the use of nano-structured membranes, the project will deliver (iii) training for a skilled workforce to continue work on developing CO2 reduction technology, and (iv) new links to industry with the need to reduce CO2 output. The research effort will lead to novel devices with benefits in future carbon credit economic systems and IP for this technology may become more and more valuable over the coming years. Solar-driven devices which would convert CO2 from the air to - for example - methanol could be operated to provide fuel for personal use or polymer precursors for industry and this would lead to a complete change in the economy back to local producers with responsible use of energy and community awareness of the production process. Impact on industry: the availability of novel technologies and materials will create a new branch of manufacturing with world-wide distribution of carbon capture devices or a new mechanism for carbon credit trading. Training of researchers during the course of the project will provide skilled workers and experts. Dissemination of researh results from this porject may also stimulate new industry based research projects into improved devices or better designs with higher economic impact. Impact on science: the new knowledge, new materials, and in particular any proof-of-principle device results will have a considerable impact in science world-wide. This will stimulate new research and a broader screening effort for improved MOF or COF materials for nanostructured catalyst systems. The effect of pore size and shape and the availablity of hierarchicallly structured membranes will provide a boost in related sectors of science and engineering. UK science will be seen as spear-heading a technological break-through with wide implications and applications. The use of novel substrate materials in catalysis and in electrocatalysis will have wider applications and may lead to further applications.