Indispensable, expensive, and rare – PGMs get a green upgrade.

Back in 1950, the first catalytic converter in the United States was a box bolted onto a car's undercarriage to reduce tailpipe emissions. It was patented by French mechanical engineer Eugene Houdry, who was concerned about the effects of automobile exhaust on the good people of Los Angeles.

And it would have worked if it had not been for the octane-boosting lead then being added to fuel, which could choke any catalyzer in short order. This would all change twenty years later with the Clean Air Act of 1970-Houdry was just too far ahead of his time.

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Platinum serves as a catalyst that convert water into hydrogen, then transform that hydrogen into electricity, with water as the only byproduct.

Today, the automotive industry is once again outpacing its own energy source. Hydrogen and electric vehicle batteries are beginning to replace gasoline, while modern catalytic converters are becoming valuable sources of platinum group metals (PGMs). As a result, the balance of demand is shifting away from fossil fuels and increasingly toward renewable energy solutions.

PGMs are vital as catalysts due to their excellent electrical conductivity, high melting points, and exceptional heat and corrosion resistance, making them indispensable in clean energy, military operations, and several key industries.

"To meet the nation's goal of net-zero carbon emissions by 2050, decarbonization of these energy and emissions intensive processes will be crucial. PGM catalysts, and the green hydrogen produced with them, can enable dramatic emissions reductions in these hard-to-decarbonize industrial sectors," Department of Energy's (DOE) Advanced Manufacturing Office PGM penned in a report on this group of hardworking precious metals.

Small, but mighty

The World Platinum Investment Council reported that PGM-based lithium battery chemistries, including next-generation lithium-oxygen and lithium-sulfur, would extend the range per charge. With this improved range, battery mass could be reduced, leading to a lighter vehicle that operates more efficiently, further enhancing the vehicle's range.

This is a significant consideration in the world of EVs, where increased power often translates to increased weight, particularly for larger vehicles like trucks. For example, the 2023 GMC Hummer EV's battery alone weighs 2,900 pounds.

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While North America hosts plenty of resource potential, enough of a jump in PGM demand can put devastating pressure on availability.

PGMs have the unusual distinction of being considered both industrial and precious metals, a designation that keeps them in high demand and a good investment. However, if PGM-reliant green technologies take off, even a small jump in demand will put devastating pressure on availability.

Major uses and mid-2024 prices for PGMs include:

• Platinum ($972/oz) – the group's namesake, and it is most recognized as a precious metal in jewelry, medical implants, and electronics, as well as a catalyst for scrubbing emissions and hydrogen technologies.

• Palladium ($904/oz) possesses the unique ability to absorb and release hydrogen, which is used in chemical processes that require hydrogen exchange, such as fuel cells, and as an excellent catalyst. Palladium is also used in capacitors and as a substitute for platinum.

• Iridium ($4,700/oz) – of which the U.S. is 100% dependent on imports, possesses notable chemical and thermal stability. Iridium-based catalysts are often used as anodes in proton exchange membrane (PEM) electrolyzers alongside platinum and palladium to boost vital chemical reactions and in the anode catalyst for hydrogen production.

• Rhodium ($4,650/oz) – and iridium are used as hardening agents for platinum palladium alloys. Rhodium is extremely corrosion-resistant and highly reflective, often used to add luster and strength to jewelry, mirrors, and headlight reflectors.

• Ruthenium ($400/oz) – another strengthening agent for PGM alloys. Due to its conductive properties and durability, it makes hard-wearing electrical contacts in electronics. Ruthenium is also used in highly efficient solar cells and as a catalyst.

A family of critical catalysts

The PGM family (except for osmium) is on America's critical minerals list due to their invaluable industry applications, rarity, and supply chain risk.

As fossil fuels are phased out in private transport and heavy industry, the use of PGMs is now shifting to hydrogen production and as catalysts in hydrogen fuel cells, potentially doubling the demand for an already strained resource.

"PGM catalysts are important to maximizing the efficiency of emerging decarbonization technologies, specifically in proton exchange membrane electrolyzers for green hydrogen production from water and PEM fuel cells for transportation and stationary energy storage," DOE penned in a 2022 report on PGMs. "Under aggressive decarbonization scenarios, such as those striving toward net zero carbon emissions by 2050, demand for PGM catalysts is expected to grow rapidly, both domestically and globally."

Iridium, one of the rarest metals on Earth, is currently the catalyst of choice for electrolyzer stacks that split green hydrogen off water molecules. Without alternatives, its scarcity threatens to create a bottleneck that could stall the adoption of the technology entirely.

Platinum is the most common metal used as a catalyst for hydrogen fuel cells that generate electricity for transportation and stationary power, but other PGMs, such as palladium and ruthenium, can serve a similar purpose. It is estimated that a hydrogen vehicle fuel cell needs 30 to 60 grams of platinum, compared to only five grams in an automotive catalytic converter.

Few and far between

In its PGM supply chain factsheet, DOE warns: "The six PGMs are among the least abundant elements on earth and occur in only a few countries worldwide, with the majority of production and reserves in South Africa and Russia. To secure the supply chains for these clean energy technologies, as well as green hydrogen and chemical manufacturing, the United States needs to invest in its domestic resources and in innovations in PGM substitutions, material efficiency, and recycling."

Key sources and projects in North American PGM production include:

• The Stillwater Complex deposit in Montana, mined since 1986, stands as the largest source of PGMs in the U.S. and boasts the highest ore grade globally. The Stillwater mine is projected to remain operational until 2053, while its neighboring East Boulder mine will continue until 2068. Sibanye-Stillwater also operates the Columbus Metallurgical Complex, which plays a crucial role in recycling catalytic converters to recover PGMs.

• Eagle Mine, operated by Lundin Mining in Michigan, produces platinum and palladium as byproducts of nickel and copper production, with small amounts of PGMs.

• Canada ranks among the top five global producers of PGMs, with its premier PGM mine located in western Ontario near Thunder Bay at the renowned Lac des Iles mine, a palladium-rich deposit also yielding gold, copper, and nickel byproducts. Approximately 73% of Canada's PGM production is concentrated in Ontario, Quebec, and Manitoba, while the remainder comes as byproducts from nickel and battery metals mining in regions like Sudbury, Quebec, Manitoba, Newfoundland, and Labrador.

• There are several junior polymetallic PGM projects in the United States, particularly in Alaska and Minnesota. In Canada, numerous additional PGM projects are also currently at the exploration stage.

The critical role of recycling

In a sense, every country has access to a plentiful PGM source through recycling, which is ten times cheaper than extraction from the ground, where every ounce and dollar counts. Recycled PGMs can be reused indefinitely, with a process that reduces carbon intensity by up to 98% compared to initial mining, seamlessly integrating sustainability with economic efficiency.

Recycled PGMs, also known as secondary supply, will be crucial for maintaining a secure domestic supply and meeting market demand. Johnson Matthey, the world's largest recycler of PGMs with over 200 years of experience, exemplifies industry success by operating in more than 30 countries and achieving an impressive 99.95% purity in its recycling processes.

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PGMs are among the least abundant elements on Earth and occur in only a few countries worldwide. To secure the supply chain, the U.S. needs to invest in its domestic resources and innovations.

In its May 2024 PGM Market Report, Johnson Matthey explains: "PGM are used in a range of industrial applications which are fundamental for improving energy efficiency, reducing CO2 emissions, and safeguarding the environment. These include glass fibre (widely used for vehicle light-weighting, and renewable energy applications such as wind turbines and solar panels), biofuels and synthetic fuels (to partly replace conventional oil-based fuels in aviation, for example), copper foil manufacture (for lithium-ion batteries), catalysts to control pollution from non-road and stationary engines, and hydrogen-related applications such as fuel cells and PEM electrolysis."

Industrialized recovery can reclaim significant amounts of PGMs, which are then reintroduced to the manufacturing supply chain, promoting circularity that benefits both the environment and economy.

PGM recycling is especially critical when exploring sustainable sourcing methods. Recovering PGMs from products such as e-waste, catalytic converters, and fuel cells is a given, while adding end-of-life solar panels and turbine blades offers an opportunity to further reduce the environmental impact of mining to meet the rising demand for these metals.

"About 120,000 kilograms of palladium and platinum were recovered globally from new and old scrap in 2023, including about 42,000 kilograms of palladium and 9,000 kilograms of platinum recovered from automobile catalytic converters in the United States." the USGS report noted.

The high cost and scarcity of PGMs are also pushing research toward reducing their use. Exploring nanomaterials, unusual alloys and experimental polymers will expand into the space occupied by PGMs over time, but this suite of silvery metals holds sway over most applications for which they are uniquely suited.

Catalyst for change

There is plenty of room for change in the field of catalysts and how they are applied to the energy transition.

Amidst the research on PGM-free alternative hydrogen catalyzers, metal and carbon nanomaterial combinations are promising candidates to help reduce or replace these rare metals in the future. Nanomaterials are being fabricated with graphene, incorporating various single-atom matrices of transition metals like iron, manganese, chromium or copper, even some simple organic compounds.

Nickel is also an abundant, cheap option under intense study. In addition to serving as a primary catalyst, nickel-based coatings offer a hard surface finish alternative to PGM-based coatings that are cost-effective, corrosion-resistant, and thermally stable – ideal for a wide range of industries and applications.

Carbon fabrics are also being embedded with minute amounts of highly functional catalysts using a conventional carbon fiber manufacturing process. These electrocatalysts boast a lifespan that is 100 times longer than conventional electrodes while maintaining optimal performance through trace amounts of ruthenium, resulting in significantly reduced manufacturing costs.

In addition to splitting hydrogen off water or hydrocarbons, researchers are investigating the potential of using PGMs, nickel, or other catalysts to produce geological hydrogen.

One such project is being conducted by a team of University of Texas at Austin scientists who are introducing nickel and PGM catalysts into iron-rich rock formations in the U.S. to produce geological hydrogen without emitting carbon dioxide, simulating the natural geologic process called serpentinization and coming full circle to learn from nature's original hydrogen production facility – planet Earth.

"If we could replace hydrogen that is sourced from fossil fuels with hydrogen sourced from iron-rich rocks, it will be a huge win," said Toti Larson, an associate professor at the University of Texas and the lead researcher on the project.