Recovering platinum from spent fuel cell assemblies with ALS2

Hydrogen fuel cells are quietly reshaping transport, heavy industry and stationary power across a growing number of markets. The membrane electrode assembly at the heart of every proton exchange membrane cell relies on a thin coat of platinum-group catalysts, and that platinum is both precious and strategically sensitive. When a stack reaches the end of its working life, the MEA, the bipolar plates and the gas diffusion layers all enter a complex waste stream that is genuinely difficult to process.

The ALS2 project, coordinated by Ikoi S.p.A. with backing from the European Union's Horizon 2020 research and innovation programme, is developing an acidless separation route for recovering precious metals from electronic waste. The technology avoids the aggressive aqua regia and strong mineral acids that dominate traditional refining, and it is particularly well suited to the fine, carbon-supported platinum particles found in MEA waste. Below is a closer look at how the process works, why it matters, and what it could mean for Australian recyclers and hydrogen players.

The chemistry hiding inside a spent MEA

A typical membrane electrode assembly is a multilayer sandwich. A proton-conducting polymer film, usually a perfluorosulfonic acid membrane such as Nafion, sits between two catalyst layers. Each catalyst layer is a few nanometres of platinum, often alloyed with cobalt or nickel, dispersed on a high-surface-area carbon support. Gas diffusion layers made from carbon paper or carbon cloth sit on the outside, and tiny amounts of platinum may even migrate into the membrane during operation.

When the stack is decommissioned, the MEA does not look like a rich ore. The platinum loading is small, often in the range of 0.1 to 0.4 milligrams per square centimetre, and it is bound up with fluoropolymers, conductive carbons and trace ionomer residues. Conventional pyrometallurgical smelters struggle to recover metal from such dilute, organic-rich feed without large energy inputs, and the fluorine content can create unwanted emissions if not managed carefully.

This is exactly the kind of feedstock that the ALS2 process was designed to handle. Rather than dissolving everything in a boiling acid bath, the technology uses a combination of thermal pretreatment and selective chemical leaching under controlled conditions to liberate platinum from the carbon support without the need for concentrated aqua regia.

Why Australia is paying close attention

Australia is going through a quiet but very real build-out of hydrogen infrastructure. Projects in the Pilbara, the Hunter Valley and around Gladstone are bringing large-scale green hydrogen production online, and ARENA-backed initiatives are funding fuel cell forklifts, buses and stationary units in places like Western Sydney and the Latrobe Valley. Every one of those deployments will eventually produce spent MEA waste.

Local recyclers are already familiar with the challenges of recovering small amounts of precious metal from complex streams. Operators running facilities that handle mobile phones, circuit boards and automotive catalysts know that a few grams of platinum can swing the economics of a whole batch. Adding fuel cell waste to that mix is both an opportunity and a headache, because the materials behave differently from the e-waste that current shredders and acid lines are tuned for.

There is also a strategic angle. Australia imports the vast majority of the platinum it uses in industry and laboratory work, and the country has no large primary platinum mine. Building domestic capacity to recover platinum from end-of-life fuel cells, electrolyser stacks and catalytic converters fits neatly with the broader push towards a circular economy and with the language of resource sovereignty that comes up frequently in policy discussions from Canberra through to Perth.

The road transport sector is another driver. Hydrogen buses on routes around Sydney's inner west and in parts of South Australia are running on cells that will need refurbishment or replacement within the next decade. The first wave of stationary fuel cell units installed at remote telecommunications towers and mine sites in the outback is also approaching mid-life. The waste these systems produce is the next resource stream Australian recyclers will be asked to process.

The acidless separation pathway

The ALS2 process, as described by the project team, is built around a series of steps that separate materials by their chemical behaviour rather than by brute-force dissolution. The feedstock is first dried, shredded and, where necessary, milled to expose the catalyst particles. A controlled thermal stage then removes organic binders, ionomer residues and the bulk of the carbon support without driving off the platinum, because the temperature window is chosen to stay below the point where fine platinum particles begin to sinter or oxidise.

After thermal treatment, the calcined material is contacted with a selective lixiviant. The lixiviant is designed to attack the platinum surface rather than to dissolve the entire matrix, so the volume of liquid used and the strength of the reagent can be kept far below what a conventional acid-based refinery would require. Dissolved platinum is then recovered from solution through precipitation or electrowinning, while the residual carbon-rich solids are washed, filtered and sent on for further handling or disposal.

Because no aqua regia is involved, the process sidesteps several of the most unpleasant aspects of traditional refining. There is no chlorine gas evolution, no red fuming acid handling, and the off-gas treatment requirements are simpler. For an Australian operator accustomed to tight workplace exposure standards and the expectations of the local environmental protection agencies, that is a meaningful practical benefit.

How ALS2 handles MEA feedstocks specifically

Treating membrane electrode assembly waste is one of the benchmark applications for the technology. The ALS2 team has run trials on real MEA scrap and on production offcuts supplied by fuel cell manufacturers, looking at both fresh and aged assemblies. The goal is to recover the platinum content at a yield and purity that meets the specification for reuse in new catalyst layers.

The first task is dealing with the membrane. Perfluorinated membranes are notoriously tough, and they do not break down easily in a water-based leach. The thermal pretreatment step in the ALS2 flow sheet is calibrated to depolymerise and volatilise much of the fluorine-containing polymer, leaving behind a friable, carbon-rich residue that the downstream leach can reach. Any fluorine released is captured for treatment, which keeps the process within the sort of emission limits that an Australian plant operating under state-level environment protection authority rules would need to meet.

The catalyst layer itself responds well to selective leaching. Once the carbon support has been partially oxidised, the platinum nanoparticles are exposed to the lixiviant and go into solution efficiently. Because the lixiviant is tuned to platinum-group metals rather than to base metals, the selectivity is high, and the downstream purification steps are correspondingly shorter. Trials have shown recoveries consistently above ninety per cent for platinum from MEA feedstocks, with comparable performance for palladium when it is present as a co-catalyst.

Residual solids from the ALS2 line, mostly carbon and trace metal oxides, are washed and stabilised. They can be routed into other recycling streams or, in some configurations, used as a reducing agent in adjacent processes. That kind of internal reuse keeps the mass balance tight and improves the overall economics, which is particularly attractive for a mid-sized recycler thinking about a compact recovery plant rather than a full refinery.

Scaling up for compact recovery plants in Australia

A compact precious-metals recovery plant built around the ALS2 process is a very different proposition from a traditional primary refinery. The footprint is smaller, the reagent inventory is lower, and the process can be containerised for deployment close to where waste is generated. For Australian operators, that opens up possibilities in regional hubs such as Newcastle, Geelong or Kwinana, where e-waste collection points and hydrogen projects already coexist.

Integrating the technology into existing e-waste lines is a logical next step. Many Australian recyclers already run shredding, sorting and mechanical separation equipment through schemes like TechCollect and the Australian New Zealand Recycling Platform. Adding an ALS2 module downstream would allow them to capture platinum, palladium and rhodium from MEA waste, automotive catalytic converters and circuit boards in a single integrated line, without the licensing and infrastructure burden of a full acid refinery.

There are still questions to work through. Feedstock preparation for MEA waste is fiddly because the assemblies are laminated, and a degree of manual or semi-automated disassembly is likely to remain part of the workflow. Effluent management, even for an acidless process, still requires careful design, particularly in regions where water is scarce and reuse is a hard requirement. And of course, the economics depend on the platinum price, on collection logistics across a country as vast as Australia, and on the willingness of fuel cell OEMs to participate in take-back schemes.

The direction of travel, though, is clear. As more hydrogen hardware comes online in Australian transport, mining and stationary power, the volume of spent MEA material will grow from a trickle into a real stream. Technologies that can recover platinum cleanly, safely and at a sensible scale will be part of the answer, and the work being done on acidless separation looks like a promising piece of that puzzle.

If you would like a closer look at the chemistry, the consortium and the pilot results, head over to the project page and explore how the technology is being put together by the researchers and industrial partners involved.