Recovery of metal value from end of life PEMFC

随着燃料电池技术在许多能源转换领域的潜在广泛采用，越来越需要解决新的方法，以回收与报废燃料电池堆相关的重大价值。燃料电池这一术语可以应用于使用各种材料的各种电化学装置；然而，具有潜在最大市场渗透率的类型是聚合物电解质膜燃料电池(PEMFC)。虽然已经有很多关于替代品的研究，但通常的电催化剂组合是基于铂和Ru的，这两种材料都非常昂贵。有几种模式，如金属租赁，可以帮助解决这一问题，但显然，在所有情况下，为了促进广泛的市场吸收，需要开发通过可扩展的路线回收这些金属的高效和有效的手段。传统的回收这些金属的技术，如火法冶金法(冶炼)，存在一些特殊的能源和环境问题，以及一些限制，使得通过这些路线大规模回收铂和Ru是不可能的。本文提出的研究旨在提供开发工艺所需的基本知识，该工艺满足以下重要要求：1)低工艺成本和复杂性2)低环境影响-直接和从能量输入的排放方面3)安全工艺3)提出了一种基于电化学闭环法的工艺，它缩短了大量的提取步骤，从而依次选择性地回收每种金属成分。理想的过程包括两个耦合的反应器，其中金属被选择性地溶解的浸出反应器和一个膜分离的电化学反应器，在其中金属从溶液中顺序沉积，同时氧化剂被再生。这一过程与正在研究的化学系统相结合，将产生一个更安全、更节能的过程，可以显著降低燃料电池的生命周期成本。然而，在部署实际进程之前，必须解决一些真正的挑战。该项目将详细探索：1)这些金属的浸出动力学和机理，以及催化剂层与膜的紧密结合如何影响回收率。2)当催化剂被层叠时，是否有足够的途径通过碳的孔结构获得贵金属，而不需要膜溶解或部分溶解过程3)每种金属成分的选择性和顺序回收，这将需要详细研究每种金属的沉积动力学，并为电化学反应堆设计合适的阴极燃料电池有望成为未来能源转换市场的重要组成部分，在英国发电的分散化和多样化方面发挥关键作用。在远程和热电联产(CHP)系统中找到应用。从原材料到系统集成商，从Intelligence Energy和Acal Energy等小型中小企业到Centrica和Johnson Matthee等大型跨国公司，英国在整个供应链中拥有一些重大利益。如果以燃料电池微型热电联产系统为例，取代目前的冷凝式锅炉技术，那么英国市场每年的价值约为150万台。为了支持这一技术转变，现在显然需要建立补充供应和回收路线，以帮助最有效和成功地采用这项技术。如果这项研究成功，通过降低生命周期成本，可以加快燃料电池在许多应用中的引入。

With potential widespread uptake of fuel cell technologies in many areas of energy conversion, there is an increasing need to address new ways to reclaim the significant value associated with end-of-life fuel cell stacks. The term fuel cell can be applied to a wide range of electrochemical devices which use a variety of materials; however, the type with potentially the largest market penetration is the polymer electrolyte membrane fuel cell (PEMFC). Although there has been much research into alternatives, the usual electrocatalyst combinations are based on Pt and Ru, both of which are extremely costly. There are several models such as metal leasing which can help address this, but clearly in all cases to facilitate broad market uptake, efficient and effective means of recovery of these metals by a scalable route needs to be developed. Traditional techniques for recovery of these metals, such as pyrometallurgical routes (smelting) has some particular energy and environmental problems as well as constraints which would make large scale recovery of Pt and Ru by these routes impossible.The research proposed here intends to provide the fundamental knowledge required for the development of a process which addresses the following important requirements:1) Low process cost and complexity2) Low environmental impact - direct and in terms of emissions from energy input3) Safe processAn electrochemical based closed loop process is proposed which short cuts a lot of the extraction steps to give selective recovery of each metal constituent in turn. The idealised process consists of two coupled reactors, the leach reactor in which the metals are dissolved selectively and a membrane divided electrochemical reactor, in which the metals are deposited sequentially from solution whilst the oxidant is regenerated simultaneously. This process in conjunction chemical systems to be investigated to facilitate it will produce a much safer and more energy efficient process which could significantly reduce the lifecycle costs of fuel cells. However, there are some real challenges that have to be addressed before a practical process could be deployed. The project will explore in detail:1) The leaching kinetics and mechanisms for these metals and how intimate lamination of the catalyst layers into the membrane affects recovery rates.2) Whether there is sufficient access to the precious metal through the pore structures of the carbons used when the catalyst has been laminated without the need for a membrane dissolution or partial dissolution process3) Selective and sequential recovery of each metal component which will require detailed investigation into the deposition kinetics of each metal and design of a suitable cathode for the electrochemical reactorFuel cells promise to be a significant part of the future energy conversion market, playing a key role in the decentralisation and diversification of UK electricity generation, finding application in remote and combined heat and power (CHP) systems. The UK has some significant interests in the complete supply chain from raw materials to system integrators with range from small SMEs such as Intelligent Energy and Acal Energy, to large multinationals such as Centrica and Johnson Matthey. If the example is taken of a fuel cell micro-CHP system, to displace the current condensing boiler technology, then the UK market is worth around 1.5 M units per year. To support this shift in technology, complementary supply and reclamation routes clearly need to be established now to help the most efficient and successful uptake of the technology. If successful this research, by reducing life-cycle costs, could quicken the introduction of Fuel Cells in many applications.