Platinum
Overview
Platinum (白金, Platinum) is a silver-white transition metal with atomic number 78 and symbol Pt, and a representative precious metal. Chemically very stable, it undergoes almost no oxidation or corrosion, and combines excellent catalytic activity, a high melting point, and outstanding ductility and malleability. It is widely known for jewelry and investment assets, but most actual consumption occurs in industrial sectors such as automotive exhaust purification catalysts, petrochemical processes, fuel cells, and anticancer drugs.
Main content
Physical and chemical properties
Platinum belongs to group 10 (period 6) of the periodic table, with a density of about 21.45 g/cm³, heavier than gold (about 19.3 g/cm³). Its melting point is 1,768°C and boiling point reaches about 3,825°C. It withstands most acids, including hydrochloric acid, nitric acid, and sulfuric acid, and dissolves only in aqua regia (王水), a mixture of the three. It does not tarnish in air, so it is called the "unchanging metal," and its thermal and electrical conductivity are intermediate among metals. In particular, its large capacity to adsorb and store hydrogen on its surface makes it highly valued as a catalyst and electrode material. Among platinum-group metals (PGMs), it has better catalytic durability than palladium and is preferred for high-temperature processes.
History and name
Indigenous peoples of the Colombia region of South America processed platinum alloys before the arrival of Europeans. In the 16th century, Spanish conquistadors called this metal, which was harder to melt than gold, "platina" (little silver) and regarded it as worthless debris. Spanish explorer Antonio de Ulloa introduced it to Europe in 1735, and its discovery was officially announced in 1748. As refining technology advanced in the 19th century, its industrial value was recognized, and in 1803 the Englishman William Hyde Wollaston developed a method for processing powdered platinum, laying the foundation for catalysis research.
Occurrence and production
Platinum is extremely rare in the Earth's crust, at about 0.005 ppm. More than 70% of world production comes from the Bushveld deposits in South Africa, followed by Norilsk in Russia, Zimbabwe, Canada, and the United States. Annual production is about 180–200 tonnes, only one-twentieth of gold production. It is often recovered as a byproduct during the smelting of nickel and copper ores, and is produced together with ruthenium, rhodium, palladium, osmium, and iridium as platinum-group elements.
Industrial applications
- Automobiles: A key component of three-way catalytic converters, converting carbon monoxide, hydrocarbons, and nitrogen oxides into harmless substances.
- Chemical processes: Used as a catalyst for nitric acid production via ammonia oxidation, petroleum reforming, and silicone manufacturing.
- Energy: Used in electrode catalysts for fuel cells and in water electrolysis devices, and is evaluated as a core material of the hydrogen economy.
- Electronics and electrical: Used in electrodes, thermocouples, nozzles for glass fiber manufacturing, and various sensor components.
- Medicine: Platinum complexes such as cisplatin, carboplatin, and oxaliplatin are used as representative anticancer drugs, and platinum is also used in pacemaker electrodes and catheters.
- Jewelry and investment: Distributed as 950 and 900 alloy jewelry, platinum coins, and platinum bullion, with the international currency code XPT.
Economy and market
Platinum prices hit an all-time high near $2,200 per ounce in 2008, then showed great volatility amid stricter diesel vehicle regulations and a shift toward palladium substitution. It is traded on the London Bullion Market Association (LBMA) and the New York Mercantile Exchange (NYMEX), and because its market is smaller than gold's, prices fluctuate widely with investment demand.
Latest trends
The key words for the platinum market in 2024–2025 are "hydrogen economy" and "supply risk." Concerns over production disruptions continued as South Africa's power supply instability overlapped with sanctions on Russia, and expectations that the spread of green hydrogen projects would increase demand for catalysts used in fuel cells and water electrolysis stimulated investor sentiment. As the perception that platinum is undervalued relative to gold spread, physical investment demand also flowed in. After palladium prices surged, the automotive industry expanded development of platinum-substitute catalysts, and the PGM recycling industry based on urban mining is also growing rapidly. In research, work is active on improving the durability of platinum nanoparticles, technologies to reduce their usage, and targeted delivery vehicles for platinum-based anticancer drugs. However, because a significant portion of platinum demand still depends on internal combustion engine catalysts, the shift to electrification is cited as a medium- to long-term risk factor.
Related topics
- [[Platinum-group elements]]
- [[Hydrogen economy]]
- [[Fuel cell]]
- [[Catalysis]]
- [[Rare metals]]
- [[Precious metals]]