Deep within the periodic table lies a low-key yet immensely powerful "superfamily"—the Platinum Group Metals (PGMs). Comprising platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), and iridium (Ir), these elements are extremely scarce in the Earth's crust and notoriously difficult to mine. Yet, together, they form the bedrock of the modern catalytic industry. As a professional platinum catalyst manufacturer, we work with these five metals every single day. To chemical engineers, materials scientists, and even procurement professionals, they are not merely expensive precious metals; they are the "magic powders" that leverage trillion-dollar industries.

So, among these five "PGM brothers," who is the absolute top star in catalysis? Today, from a professional perspective, we will break down their unique superpowers and primary domains.

Platinum (Pt): The Versatile Veteran of Catalysis

If we had to pick the undisputed "big brother" of the PGM family, it would undoubtedly be platinum. Platinum is the ultimate "all-rounder veteran" in catalysis; its electronic structure endows it with exceptional ability to adsorb and activate small molecules.

In petrochemicals, platinum is the core of the reforming process, converting low-octane naphtha into high-octane gasoline components and aromatics. In organic synthesis, whether it's classic hydrogenation and dehydrogenation or hydrosilylation, platinum-based catalysts (such as Speier's and Karstedt's catalysts) are the industry standard. In recent years, driven by the new energy wave, platinum has proven irreplaceable in the cathode oxygen reduction reaction (ORR) of Proton Exchange Membrane Fuel Cells (PEMFC). Although we are constantly striving to reduce the loading, platinum remains the most ideal fuel cell catalyst material today.

Furthermore, chloroplatinic acid and its derivatives are indispensable raw materials in fine chemicals and pharmaceutical intermediates. Platinum boasts extreme stability, maintaining its activity in harsh acidic, alkaline, and high-temperature environments. This "rock-solid" reliability makes it the most trusted partner in the industrial sector.

Palladium (Pd): The Rising Star of Coupling Reactions

If platinum is the versatile veteran, then palladium is the "current superstar" of the catalysis world. Palladium’s most dazzling achievement is its dominance in cross-coupling reactions. When the 2010 Nobel Prize in Chemistry was awarded for palladium-catalyzed cross-couplings, reactions like Suzuki, Heck, and Sonogashira became the "magic weapons" for constructing carbon-carbon and carbon-heteroatom bonds.

In pharmaceuticals, agrochemicals, and advanced materials synthesis, palladium catalysts make the construction of highly complex molecules both efficient and precise. Beyond fine chemicals, palladium plays a pivotal role in automotive exhaust purification. In three-way catalytic converters for gasoline vehicles, palladium is the main force in oxidizing carbon monoxide and hydrocarbons. Driven by an explosion in industrial demand in recent years, palladium prices have frequently surpassed those of platinum, giving it a dual identity as both an industrial metal and a financial asset. For procurement professionals, palladium's price fluctuations often directly trigger tremors across the entire fine chemical supply chain.

Rhodium (Rh): The Eco-Guardian of Emission Control

Among the five PGM brothers, rhodium has historically hit record-high prices, earning its reputation as one of the "most expensive industrial metals." The reason for this premium is its irreplaceable role in automotive three-way catalytic converters: the reduction of nitrogen oxides (NOx).

In exhaust treatment, while platinum and palladium excel at "oxidation," rhodium specializes in "reduction." It efficiently converts harmful NOx into harmless nitrogen (N₂) and oxygen (O₂). As global environmental regulations become increasingly stringent and no perfect, cheap alternatives exist, rhodium's supply and demand remain in a long-term tight balance. Beyond environmental protection, rhodium also plays a crucial role in homogeneous catalysis (such as methanol carbonylation to acetic acid) and optical coatings. Rhodium possesses extreme corrosion resistance, remaining stable even in boiling aqua regia. This ultimate chemical inertness cements its king-like status in extreme operating conditions.

Ruthenium (Ru): The Game-Changer in Olefin Metathesis

For a long time, ruthenium was considered the "supporting actor" of the PGM family. However, in recent years, it has successfully "broken through" thanks to its outstanding performance in olefin metathesis. Grubbs catalysts, based on ruthenium, have completely transformed the landscape of polymer synthesis and medicinal chemistry.

Compared to traditional titanium- and tungsten-based metathesis catalysts, ruthenium-based catalysts exhibit extremely high tolerance to air and moisture, along with excellent functional group compatibility. This allows for complex molecular tailoring under remarkably mild conditions. Additionally, as a second-generation catalyst in ammonia synthesis, ruthenium has demonstrated higher activity than traditional iron-based catalysts. In water electrolysis for hydrogen production and oxidation reactions, ruthenium-based oxides are also highly promising non-precious metal alternatives. The rise of ruthenium proves that in the catalysis world, there are no permanent underdogs—only untapped potential waiting to be discovered.

Iridium (Ir): The Future Pioneer of the Green Hydrogen Era

Finally, we have iridium, the youngest and most futuristic "pioneer" of the PGM family. With the highest melting point and unmatched corrosion resistance among precious metals, it is the ultimate choice for extremely acidic environments.

In the currently booming green hydrogen sector, Proton Exchange Membrane (PEM) water electrolysis is viewed as the future mainstream technology. At the anode of PEM electrolyzers, the highly demanding oxygen evolution reaction (OER) takes place. Currently, only iridium-based catalysts can simultaneously meet the requirements for high activity and ultra-long lifespan. Simply put, without iridium, there is no highly efficient and stable PEM water electrolysis technology. Furthermore, iridium shows immense potential in photocatalysis, C-H bond activation, and OLED emissive materials. Although its absolute usage currently trails behind platinum and palladium, with the explosive growth of the green hydrogen industry, iridium's strategic importance is skyrocketing.

Head-to-Head Comparison: Who is Your "Optimal Solution"?

As a manufacturer, when helping clients select materials, we typically conduct a comprehensive evaluation across four dimensions:

Catalytic Activity: In a specific reaction, who has the higher Turnover Frequency (TOF)? For example, palladium for coupling reactions, platinum for fuel cells, and iridium for PEM water electrolysis.

Selectivity: Who can more precisely yield only the target product while minimizing side reactions? Ruthenium is unrivaled in selectivity for metathesis.

Stability: Who can last the longest under strong acids, strong alkalis, and high temperature/pressure? Rhodium and iridium far outlast their siblings in extreme environments.

Price & Abundance: Platinum and palladium have relatively mature supply chains, but their prices are heavily influenced by macro-financial factors. Rhodium and iridium are extremely scarce, resulting in exorbitant and highly volatile prices. Ruthenium is relatively cheaper, offering a highly cost-effective alternative.

Conclusion: There is No Absolute MVP, Only the Perfect Fit for the Scenario

Let’s return to our initial question: Among platinum, palladium, rhodium, ruthenium, and iridium, who is the true top star of catalysis?

As a professional catalyst manufacturer, our answer is: There is no absolute "MVP" in catalysis, only the "most suitable scenario." Platinum is the versatile cornerstone, palladium is the synthesis weapon, rhodium is the eco-guardian, ruthenium is the molecular scissor, and iridium is the green hydrogen pioneer. Each has its strengths, and each has its limitations.

In practical industrial applications, we are rarely choosing just a single metal. Instead, we design multi-metal synergistic systems, or push their performance to the absolute limit through nano-engineering and single-atom technologies. In the future, as cutting-edge technologies like AI-assisted catalyst design and single-atom catalysis become a reality, these five "PGM brothers" will undoubtedly spark even more astonishing innovations.


Diethylenetetramethyldisiloxane platinum complex (platinum catalyst) MY 8115-Mingyi Silicone