Rare and expensive, the platinum group metals (PGMs) are desirable as precious metals for investment and jewellery. But as industrial metals, being rare and expensive reduces their appeal. While this does not lessen their widespread use – in numerous settings, there is simply no workable alternative – it does dampen enthusiasm to find new ways to use PGMs.
At worst, some researchers may be trying to replace PGMs in a functional technology with an alternative material, typically a base metal – even at the risk of hampering the optimal functioning of the technology in question. It is the position of many research groups that PGMs should be substituted with more ‘earth-abundant’ metals such as nickel wherever possible, because of the perceived benefits for sustainability and cost, which may even justify some performance trade-off.
In fact, the avoidance of PGMs in innovation is largely based in misperception; there are good reasons why scientists and engineers should feel justified not just in retaining PGMs in current technologies, but also in investigating new PGM-enabled technologies to address unmet needs and unsolved challenges. We call this the PGM opportunity.
The opportunity derives from the special properties of PGMs, coupled to the unique profile of PGM supply and demand. A wider understanding of these is needed to ensure that the PGM opportunity is fully exploited.
A JM analysis found that just over 80% of the small molecule drugs approved by the FDA in 2023 were likely to contain at least one PGM-catalysed reaction in their synthesis.
The Power of PGMs
The PGMs are potent catalysts, and there are many chemical processes that would not work effectively without them. This is perhaps most obvious in their use as emissions control catalysts in vehicles, where only PGMs can convert pollutants to much less harmful substances quickly and efficiently enough in the short time it takes for exhaust gases to pass through the catalytic converter. In this setting with its stringent requirements, no compromise on performance is possible and PGMs have been the only viable option for over fifty years.
But this unmatched catalytic power also enables processes – far too many to list here – that make numerous fuels, chemicals, fertilisers, and pharmaceuticals. For example, a JM analysis found that just over 80% of the small molecule drugs approved by the FDA in 2023 were likely to contain at least one PGM-catalysed reaction in their synthesis.
As metals, the PGMs are corrosion resistant with high-temperature durability. This set of properties opens up another sphere of application, in everything from aircraft engines to making fibreglass and display screen glass. And then a diverse set of more esoteric properties sees PGMs feature heavily in the electronics world, notably in hard disks for data centre storage and various components for electronic circuits, and in healthcare, within a variety of devices and diagnostics and in core anticancer treatments.
Taken together, it is no exaggeration to say that PGMs are fundamental to modern life. This should challenge the perception that PGMs are too rare to be employed in large-scale applications.
It is no exaggeration to say that PGMs are fundamental to modern life. This should challenge the perception that PGMs are too rare to be employed in large-scale applications.
Metal Efficiency
But how is it possible that metals supplied in quantities of just a few hundred tonnes a year can do all this? The answer lies in the high efficiency with which PGMs are used, a combination of low intensity (very little metal is needed to deliver the required impact) and high recyclability (each atom of metal can be reused multiple times, without losing any of its properties). This is the missing part of the equation: the rarity of PGM supply is matched by the thriftiness of PGM consumption.
This thriftiness must be considered when calculating the actual cost of PGM in a technology. Comparing, for example, the cost of a gram of palladium to a gram of nickel and assuming that palladium is the expensive option is far too simplistic. Once lower metal loading, higher metal recycling, and a more effective process are accounted for, palladium may emerge as the cheaper option. As counterintuitive as it seems, this is often why PGMs will not be replaced even in applications where base metals are technically an alternative.
The same applies to carbon footprint, where a comparative lifecycle analysis may reveal the PGM as the more sustainable option. Such an analysis is particularly necessary in applications that tend to retain and reuse their metal through closed-loop recycling: the carbon footprint of recycled PGMs today is about 97% lower than when they are first mined.
Thriftiness tends to increase the longer a PGM is used within a technology. Ongoing technological development and refinement is a feature of many PGM applications – not least to minimise cost. This either results in the amount of PGM within the technology decreasing, or the same amount of metal delivering more output.
An example of the former is platinum and iridium used as catalysts in proton exchange membrane fuel cells and electrolysers in the hydrogen economy, where the quantities required today are an order of magnitude lower than on first invention – with further reductions in the pipeline.
Automotive emissions control catalysts are a good example of the latter: globally, the average amount of PGM used in a catalytic converter today is not much more than the quantity used decades ago. And yet the catalytic converters on modern cars remove an order of magnitude more pollutants from the exhaust stream than was acceptable a couple of decades ago.
Supportive Market Dynamics
Although the PGMs are geologically rare, this does not equate to scarcity.
The largest PGM deposit on Earth is the Bushveld Igneous Complex in South Africa, and that ore contains PGMs at parts per million level. A tonne of rock must be mined and processed to produce just a few grams of PGMs. This compares to copper and nickel ores where ore grades are measured in percentages and a tonne of rock yields kilograms of metal.
Clearly, then, copper and nickel are far more abundant. But regardless of geological abundance, if demand for a metal outstrips supply, scarcity occurs. And this is what is feared for metals such as copper, as demand in the energy transition grows and supplies fail to keep up.
PGMs have an entirely different dynamic. The Bushveld Complex, and other well-known deposits in Zimbabwe, North America, and elsewhere, host enough PGMs to last for decades at current mining rates. Supplementing what sits below ground, decades of PGM use have established large ‘urban mines’ – metal above-ground that is a source of future supply by virtue of the recyclability of PGMs. The most important of these urban mines is the vast numbers of catalytic converters still in use on the world’s roads, which will be a source of low-carbon PGM supply for decades.
Catalytic converters for new vehicles are still the largest PGM market, accounting for over 60% of PGM demand. The rise of hybrid vehicles and tightening emissions standards worldwide mean that demand remains robust, but it will gradually transition as pure battery vehicles take market share. This opens up space to accommodate new markets for PGMs, and specifically for palladium, platinum and rhodium, the three PGMs used for automotive emissions control. Indeed, replacement markets for these three metals are being actively sought by the PGM industry to fully exploit its supply capabilities.
Mature Infrastructure
Their long history of widespread industrial use and recycling means that PGM-using technologies benefit from mature supply chains, plus well-established processing infrastructure and global recycling networks. These are centred in the UK and wider Europe, US and Japan. While China has a healthy appetite for PGMs, it plays a minimal role in global supply chains, in contrast to many other metals.
Although some new processing steps may be needed to facilitate new PGM applications, these will still benefit from existing infrastructure and assets. This greatly lowers the cost and shortens timelines to implement value chains for new PGM technologies and materials.
PGMs enable R&D in innovative technologies to tackle global challenges.
Advanced techniques are used to ensure each atom of PGM is used as efficiently as possible (transmission electron microscopy image of a catalyst (Source: JM)
PGM chemical production uses existing infrastructure and supply chains (reaction vessel shown).
PGM sponge (powder): precious yet primarily used as industrial metals.
New Markets
So the PGMs have much to offer novel and nascent applications. This matters, because there are many areas in which new technologies are sorely needed to address rising challenges.
Applications within the hydrogen economy are a prominent example. PGMs are not limited to catalysts for fuel cells and electrolysers, but also feature in hydrogen storage and transportation, sensing, anti-corrosion plating, and hydrocarbon processing applications. An example of the latter is the use of PGM catalysts in fuel processing for solid oxide fuel cells that are highly efficient power sources for data centres.
The need for hydrogen in the energy transition has been challenged by commentators who cite the superior energy efficiency of direct electricity use and batteries. However, this ignores the intense metal needs of both batteries and electricity infrastructure: simply put, there just is not enough copper, lithium, nickel and other critical metals available to allow electrification to cater to most of our energy use. PGM-based hydrogen technologies make much more efficient use of metal overall and have a crucial role to play in enabling a sensible energy transition within resource limitations.
But there are many other interesting application areas for PGMs emerging beyond hydrogen. A brief overview of two of these areas explains why focusing on the ‘cost’ of PGMs risks being blind to their true value:
The chemicals industry faces a challenging evolution to more sustainable practices. In the production of fuels and chemicals from renewable feedstocks, PGMs have the tolerance to handle a new spectrum of impurities. The PGMs are also being explored for their catalytic ability to break down ‘forever chemicals’ such as PFAS, chlorinated organic pollutants and volatile organic compounds before these toxic substances can escape into the environment, and to enable more sophisticated plastics recycling processes.
A digital revolution is underway alongside the more widely discussed energy transition, which will create increasing demand for high-performance metals. PGMs are of interest in advanced semiconductor production, in data storage – in ferroelectric capacitors, dynamic random access memory (DRAM) and non-volatile memory – and as contact and resistor materials. In the drive towards microminiaturisation, a wider spectrum of applications is expected in which the unique properties of PGMs are required to deliver high unit performance.
Seizing the Opportunity
There is growing excitement around PGMs and what they have to offer to innovation as the myths around scarcity and expense are examined and dismissed. With efficient infrastructure already in place, PGMs will continue to be supplied and have a long and beneficial lifetime above ground. Small but mighty, they are already intrinsic to every aspect of modern life, and their developing applications will contribute to solving some the world’s most urgent and complex problems.
More info at: PGM recent publications | Johnson Matthey
There is growing excitement around PGMs and what they have to offer to innovation as the myths around scarcity and expense are examined and dismissed.
