Catalysts and Chemical Applications of Critical Minerals

Catalysis is one of the oldest and most economically significant applications of critical minerals, underpinning processes that account for roughly 90 percent of all chemical products manufactured worldwide. From the platinum-group metal catalysts that clean automotive exhaust to the rare earth-based catalysts that crack petroleum into gasoline, critical minerals are essential to the chemical infrastructure of modern civilization. As the world pivots toward green hydrogen and sustainable chemistry, the catalytic applications of these minerals are evolving but not diminishing.

Platinum Group Metals in Automotive Catalysis

Catalytic converters in internal combustion engine vehicles are the single largest consumer of platinum group metals (PGMs), consuming approximately 40 percent of global platinum, over 80 percent of rhodium, and roughly 30 percent of palladium production. These devices use a wash-coated honeycomb substrate loaded with fine particles of platinum, palladium, and rhodium to convert toxic exhaust gases, carbon monoxide, nitrogen oxides, and unburned hydrocarbons, into less harmful carbon dioxide, nitrogen, and water.

Palladium has been the primary PGM used in gasoline vehicle catalytic converters, while platinum has historically been preferred for diesel applications. Rhodium is essential for reducing nitrogen oxides and has no viable substitute in this role, which is why rhodium prices reached extraordinary peaks above $29,000 per ounce in 2021. South Africa produces approximately 70 percent of the world's platinum and over 80 percent of its rhodium, while Russia is the second-largest palladium producer. This geographic concentration, combined with the lack of substitutes for rhodium's catalytic function, makes automotive catalysis one of the most supply-constrained applications of critical minerals.

Petroleum Refining Catalysts

The petroleum refining industry consumes critical minerals in several catalytic processes. Fluid catalytic cracking (FCC), the process that converts heavy oil fractions into lighter gasoline-range products, relies on zeolite catalysts enhanced with rare earth elements, particularly lanthanum and cerium, which improve catalyst stability and activity. The FCC catalyst market consumes tens of thousands of metric tons of rare earth oxides annually, making it the second-largest rare earth application after permanent magnets.

Hydroprocessing catalysts, used to remove sulfur, nitrogen, and metals from petroleum feedstocks, are typically based on molybdenum and cobalt or nickel supported on alumina. Platinum and palladium catalysts are used in reforming processes that produce high-octane gasoline components and aromatics for the petrochemical industry. While the long-term trajectory of petroleum demand is downward in decarbonization scenarios, refinery catalyst consumption remains substantial in the near to medium term and competes with other applications for the same critical mineral supply.

Green Hydrogen and Fuel Cell Catalysts

The emerging hydrogen economy introduces new catalytic demand for critical minerals. Proton exchange membrane (PEM) electrolyzers, which produce green hydrogen by splitting water using renewable electricity, use iridium and platinum as electrode catalysts. Iridium is particularly supply-constrained: global annual production is only about 7 to 8 metric tons, almost entirely as a byproduct of platinum mining in South Africa. Current PEM electrolyzer designs use roughly 0.3 to 1 gram of iridium per kilowatt of capacity, and projected hydrogen production targets would require iridium quantities that significantly exceed current supply if loading levels are not reduced.

PEM fuel cells, which convert hydrogen back to electricity for vehicles and stationary power, also require platinum catalysts, though the platinum loading per fuel cell has been reduced dramatically over the past two decades. A modern fuel cell vehicle uses approximately 30 to 40 grams of platinum, down from over 100 grams in early designs. Alkaline electrolyzers use nickel-based catalysts and avoid PGM requirements, but PEM systems are preferred for their dynamic response capability, which makes them better suited to coupling with variable renewable energy sources.

Rare Earth Catalysts in Emissions and Chemical Processing

Cerium oxide, derived from the most abundant of the rare earth elements, serves as an oxygen storage component in automotive three-way catalytic converters. Cerium's ability to readily cycle between Ce3+ and Ce4+ oxidation states allows it to buffer oxygen levels in the catalytic converter, improving performance under varying engine conditions. Lanthanum-based perovskite catalysts are being explored for next-generation automotive and industrial emissions control systems.

In the chemical industry, rare earth catalysts are used in the production of synthetic rubber, petroleum-based polymers, and specialty chemicals. Cerium oxide is also used as a polishing compound for glass and semiconductor wafers, where its chemical-mechanical properties enable atomically smooth surface finishes. The broad range of catalytic applications for rare earth elements means that even if permanent magnet demand were to plateau, catalytic and chemical uses would sustain substantial rare earth consumption.

Cobalt and Manganese in Industrial Catalysis

Cobalt is a key catalyst in the Fischer-Tropsch process for converting synthesis gas (a mixture of carbon monoxide and hydrogen) into liquid hydrocarbons. This process is used in gas-to-liquids plants and is being explored for sustainable aviation fuel production from biomass-derived syngas. Manganese dioxide serves as a catalyst and catalyst support in various oxidation reactions. Both metals face the supply concentration challenges described elsewhere in this hub, with cobalt dominated by the DRC and manganese by South Africa and Gabon.

The Transition from Tailpipe to Electrolyzer

The shift from internal combustion engines to electric vehicles will gradually reduce PGM demand from catalytic converters, but the growth of hydrogen fuel cells and electrolyzers could partially offset this decline. The net effect on PGM markets depends on the pace of EV adoption, the scale of hydrogen economy deployment, and the success of efforts to reduce catalyst loading in fuel cells and electrolyzers. What is certain is that catalytic applications will remain a significant and strategically important consumer of critical minerals through the energy transition and beyond, even as the specific minerals and applications evolve.