Autocatalysts: Production route
Three-way, oxidation or SCR: matching catalyst to engine
What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.Autocatalysts are engineered systems rather than one chemical. The main product types are matched to engine and rule: three-way catalysts for petrol and hybrids, oxidation catalysts plus particulate filters and selective catalytic reduction for diesel, and gasoline particulate filters for direct-injection petrol under Euro 6 and China 6. Coaters buy substrates, make washcoats, and apply metal that is often owned or financed by the carmaker. Formulation decides how many grams of costly metal a model needs, which is where suppliers compete.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Three-way catalyst (TWC) | most petrol and hybrid cars | typically 2-7 g PGM per car (indicative) | coating plants making millions of bricks a year (indicative) | over 90% conversion of CO, HC and NOx once warm (indicative) | none; small N2O and NH3 slip | metal dominates: at Oct 2026 prices 4 g of PGM is roughly $150-250 (indicative) |
| Diesel oxidation catalyst and particulate filter (DOC + DPF) | all modern diesels | platinum-rich, a few grams per car, more per truck (indicative) | as above | over 95% particulate mass removal (indicative) | ash builds up from lubricant additives (see lubricant_additives) | not published |
| Selective catalytic reduction (SCR) and ammonia slip catalyst | all heavy-duty and many light-duty diesels | zeolite or vanadia washcoat; little PGM | large bricks on trucks | over 90% NOx conversion when warm (indicative) | N2O traces | not published |
| Gasoline particulate filter (GPF) | most new petrol cars in Europe and China (indicative) | small PGM loadings | as above | not published | none | not published |
How each route works
Three-way catalyst (TWC)Palladium and rhodium (and increasingly platinum) on ceria-zirconia and alumina on a cordierite honeycomb. Works only near stoichiometric air-fuel ratio, controlled by oxygen sensors. Close-coupled and underfloor bricks deal with cold start and full-load.
Mature and effective; demand ends with battery cars.
palladium and rhodium tiles; indicative Diesel oxidation catalyst and particulate filter (DOC + DPF)A platinum-palladium oxidation catalyst burns CO and hydrocarbons and makes NO2 that helps burn soot trapped in a silicon carbide or cordierite wall-flow filter.
Platinum demand anchor; European diesel decline hurts.
platinum tile; indicative Selective catalytic reduction (SCR) and ammonia slip catalystUrea solution (AdBlue) injected into exhaust decomposes to ammonia, which reduces NOx to nitrogen over copper-chabazite zeolite or vanadia-titania. A small platinum catalyst removes leftover ammonia.
Low PGM; needs urea supply (urea tile).
indicative Gasoline particulate filter (GPF)Coated wall-flow filter for direct-injection petrol engines, often carrying three-way catalyst functions, required by particle-number limits in Euro 6d and China 6.
Added content per car under stricter rules.
indicative Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.