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Material World
Element · Pd

Palladium

The catalytic metal that cleans petrol engine exhaust, absorbs hydrogen like a sponge, and briefly became more valuable than gold.

Palladium is a soft, silvery platinum-group metal, obtained largely as a by-product of nickel and platinum mining, with production concentrated in Russia and South Africa. That concentration makes its price unusually sensitive to political events.

It has one genuinely strange property: it absorbs hydrogen in enormous quantity relative to its own volume, the gas dissolving into the metal lattice and being released again on heating. This is the basis of hydrogen purification membranes and was the subject of the cold fusion claims of the late twentieth century.

Uses

Catalytic converters dominate demand. Palladium is particularly effective at oxidising unburnt hydrocarbons and carbon monoxide in petrol engine exhaust, and tightening emissions standards drove its price above gold's.

It is also used in multilayer ceramic capacitors, in dental alloys, in electrical contacts, and in the palladium-catalysed coupling reactions that are now among the most-used tools in synthetic chemistry. White gold and some jewellery alloys contain palladium, and hydrogen purification depends on it.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is sourced from

  • Nickel — element · obtained largely as a by-product of nickel mining
  • Platinum — element · and of platinum mining

is used as

  • Catalysis — application · oxidises unburnt hydrocarbons and carbon monoxide in petrol exhaust

is produced by

  • Electrorefining — process · from the anode slimes of copper and nickel refining, alongside platinum

is an alternative to

  • Platinum — element · in autocatalysts, and the clearest case of substitution tracking price: carmakers moved to palladium when platinum was expensive and back again when palladium overtook it. The two are not interchangeable across the board — diesel exhaust needs platinum

is used in

  • Catalytic converter — object · in petrol exhaust, and the largest single use of the metal in the world

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • PubChem
    US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
  • NIST — National Institute of Standards and Technology
    United States Department of Commerce · US Government work — public information, credit requested

Questions this page answers

Where it comes from, and what it becomes

Follow Palladium back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Palladium → is sourced from (obtained largely as a by-product of nickel mining) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation → takes as input (the feedstock, and an unusual one in being free, unlimited and available anywhere — the cost is entirely the energy to liquefy it) → Air
  • Palladium → is sourced from (and of platinum mining) → Platinum → is produced by (collected in the slimes, where the copper's own refining concentrates it) → Electrorefining → takes as input (as impure smelted anodes, around 99% copper, which is not pure enough for wire) → Copper → is produced by (as blister copper, refined electrolytically afterwards) → Smelting → takes as input (roasted to drive off sulfur, then reduced to copper) → Chalcopyrite
  • Palladium → is produced by (from the anode slimes of copper and nickel refining, alongside platinum) → Electrorefining → takes as input (as impure smelted anodes, around 99% copper, which is not pure enough for wire) → Copper → is produced by (as blister copper, refined electrolytically afterwards) → Smelting → takes as input (as the element removed, not added) → Oxygen → is produced by (the largest output by tonnage, and the reason air separation units sit beside steelworks) → Air separation
  • Palladium → is sourced from (obtained largely as a by-product of nickel mining) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (roasted to drive off sulfur, then reduced to copper) → Chalcopyrite
  • Palladium → is sourced from (obtained largely as a by-product of nickel mining) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (reduced with carbon to metallic tin) → Cassiterite
  • Palladium → is sourced from (obtained largely as a by-product of nickel mining) → Nickel → is produced by (reduced from roasted pentlandite concentrate, with the platinum-group metals following into the refinery) → Smelting → takes as input (reduced with coke in a blast furnace) → Hematite

These are the most distinct paths back. Palladium can be traced through others besides.

Downstream — what it becomes

  • Palladium → is used in (in petrol exhaust, and the largest single use of the metal in the world) → Catalytic converter → is used as (the largest catalytic application by metal value there is) → Catalysis
  • Palladium → is used as (oxidises unburnt hydrocarbons and carbon monoxide in petrol exhaust) → Catalysis