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

随着化石燃料的燃烧和自然二氧化碳来源产生的额外正反馈效应，二氧化碳水平稳步上升。太阳能/可再生能源驱动的二氧化碳回收利用是解决这一问题的有效途径。在最近一期专门讨论这一问题的《科学》杂志(2009年9月25日)中，强调了从露天吸收二氧化碳(而不是在生产过程中捕获二氧化碳)所产生的机会和潜在的好处。捕获和利用二氧化碳的迫切需要不言而喻。目前，对二氧化碳捕集和二氧化碳利用的研究是基于一系列独立的技术，而且往往无效，例如对胺或碱的封存。通过将(纳米集成)捕获和利用结合到一个单一的连续过程中，可以提高效率，同时将推动二氧化碳减排所需的能源降至最低。该项目的重点是通过直接将催化剂与新型二氧化碳吸收装置连接起来，实现一步法二氧化碳捕获和利用。二氧化碳吸收和利用过程的纳米级集成将提供新的高效的单步过程，将二氧化碳转化为有用的产品(聚合物、碳水化合物、燃料)。该项目的主要愿景是将催化剂纳米结构嵌入/固定在二氧化碳供给膜(金属有机骨架，MOF)衬底上，以便增强局部扩散可以将高速率的二氧化碳输送到活性催化剂位置。金属有机骨架(MOF)已成为吸收和储存二氧化碳的领跑者，但从未被用于支撑催化剂。人们已经发现了将二氧化碳转化为有用的化学产品的有效催化剂，但通常需要高浓度的工业二氧化碳。在这个项目中，西南地区现有的两个优势领域--二氧化碳吸收和催化利用--结合在一起，提供了新的纳米结构功能催化膜，该膜可以从自由大气中捕获和浓缩二氧化碳，并在单一的连续工艺中将其转化为有用的产品。基于功能化和专门定制的MOF膜开发的技术将是全新的。催化过程将由太阳能(光催化或生物催化)、可再生能源或碳生成过程产生的废热驱动。纳米技术是这个项目不可或缺的一部分。金属有机骨架(MOF)是一种很有前途的吸收和储存高浓度二氧化碳的材料。在一种新的方法中，MOF将被制成纳米结构的薄膜，它将从大气中浓缩二氧化碳，并直接将其送入纳米结构的催化层。随着二氧化碳的还原，新鲜的二氧化碳会随着位于扩散层的催化剂不断地被吸入(二氧化碳在纳米催化剂上的扩散是有效的半球形)。将研究三种类型的催化剂用于二氧化碳还原：(I)使用纳米结构催化剂和集成的MOF/催化剂材料将二氧化碳直接气相还原为CO，用于一步碳捕获和利用；(Ii)二氧化碳将在铂或铜纳米颗粒(或类似的纳米结构催化剂)上电还原，生成乙烯和更高碳氢化合物，纳米结构催化剂增加工艺的选择性；(Iii)在MFC装置中，将使用蓝藻生物膜在光照下固定MOF中的二氧化碳。具有生物膜的导电MOF表面的纳米结构对于良好的细菌粘附性和功能是极其重要的。在项目的第二阶段，有效模块的阶段(例如生产乙烯和生产CO)将被组合到反应器中以提供更高价值的产品(例如聚合物、溶剂或燃料)。零件和整个过程将通过生命周期分析进行仔细评估，所需的最终产品将是碳负向过程。

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 .