JOHANNESBURG (miningweekly.com) – The use of ruthenium in fuel cells is poised to turn down in line with the growing trend towards the generation of green hydrogen.
“We believe that the use of ruthenium in fuel cells will come down, as the trend to green hydrogen will bring with it purer feeds with less carbon monoxide impurities, which basically means you no longer need the ruthenium to prevent the activity loss on the anode side,” Heraeus Precious Metals executive VP new business development and innovation Philipp Walter told Mining Weekly in a Zoom interview. (Also watch attached Creamer Media video.)
The increasing purity of hydrogen generated by electrolysis rather than steam-methane-reformed petrochemically derived hydrogen reduces the need for ruthenium-based catalysts.
But the importance of ruthenium might increase if it is able to play a role as a substitute for rhodium and iridium – as well as play additional roles in the semiconductor field.
Ruthenium supply is in balance and from a price perspective, the price of ruthenium is well below the sky-high levels of rhodium and iridium, meaning there could be future demand if ruthenium is found to be a suitable replacement for its fellow platinum group metals (PGMs) in, for example, emission catalysts.
In fuel cells, ruthenium is one part of a bimetallic catalyst system, with the other metal being platinum. The role of the ruthenium is to oxidize the carbon monoxide. By doing so, the carbon monoxide is removed from the surface of the platinum to prevent surface clogging, which lowers the activity of platinum-based electrocatalysts in fuel cells.
Ruthenium fulfills this activity-enhancing role in both methanol and hydrogen fuel cells. However, the overall need for ruthenium-based catalysts is reducing because of the increasing purity of the hydrogen generated by electrolysis, compared with the less pure steam-methane-reformed petrochemically derived hydrogen.
“You’re talking here about 0.03 g to about 0.07 g of ruthenium per kilowatt,” said Walter.
Mining Weekly: What is the outlook for the ruthenium price in 2021?
Walter: It’s, of course, always a question of the crystal ball but in general the price of ruthenium has increased lately following the overall trend of price hikes but to a lesser extent and driven mainly by speculation.
What product range consumes the biggest volume of ruthenium?
The main application is in hard disk drives and hard disk drive producers are the biggest consumers of ruthenium at the current point in time.
Could ruthenium potentially fulfill the role of other PGMs that are in short supply?
Ruthenium is debated in some applications as a potential replacement for rhodium and iridium, together with other formulation components, other metals.
Just as platinum is being considered as a substitute for high-priced palladium could ruthenium substitute scarce rhodium and iridium?
Investigations into this are ongoing. If you look at rhodium and iridium and their skyrocketing prices, it will be advantageous if ruthenium, together with other components, can help, in certain applications, to minimise use rhodium and iridium. That’s an ongoing development, I would say.
Does this potential substitution by ruthenium look promising, or is there still a long way to go?
Personally, I believe there’s still some way to go.
Mining Weekly can report that ruthenium and platinum are used in fuel cells for the same fundamental reasons as they are in the automotive and chemical industries – they are excellent catalysts that make chemical reactions take place at higher speed, at lower temperature and at higher rates of conversion than would otherwise be the case – and they are robust under a fuel cell’s harsh operating conditions, as Heraeus Precious Metals reports on its website.
They are both part of the PGMs range that is hosted and mined overwhelmingly in South Africa and are receiving increasing global attention as a result of the positive role they can play in the hydrogen economy, as well as in climate change mitigation.