Technology · Established
Precious-metal surfaces that change exhaust chemistry
Platinum’s automotive role depends on particle size, support materials and the chemistry of the engine exhaust.
THE MATERIAL THAT DOES THE WORK
Chemical form
Automotive use finely divided platinum-group metals on supporting structures. Platinum, palladium and rhodium play different roles in different formulations. The functional material is a supported catalyst with accessible surface, rather than a solid precious-metal block.
- 01
Prepare active surfaces
Small precious-metal particles are distributed on support materials, making surface available without filling the converter with bulk metal.
- 02
Match the exhaust
The formulation and system position are chosen for diesel or the different requirements of a gasoline catalyst.
- 03
Convert and recover
Exhaust molecules react at the catalyst during use; collected spent converters can later supply recovered platinum-group metals.
What metal is in a catalytic converter?Diesel oxidation catalystChallenges and Opportunities for Platinum in the Modern Three-Way Catalyst
Why it works
In a diesel oxidation catalyst, oxidation converts carbon monoxide to carbon dioxide and hydrocarbons to carbon dioxide and water. It can also oxidize nitric to nitrogen dioxide, helping establish conditions for reactions in downstream treatment components.
How it is made & used
For gasoline applications, engineers can modify ceria–zirconia supports or combine platinum with another platinum-group metal. These changes can improve stability and activity. The distribution and surroundings of platinum are part of the catalyst design.
Challenges and Opportunities for Platinum in the Modern Three-Way Catalyst
Inside the application
Diesel exhaust treatment is a sequence of cooperating components. An oxidation catalyst does not perform every cleanup step: particulate filtration and selective catalytic address other pollutants. Platinum-rich catalysts can therefore operate alongside components based on different chemistry.
What metal is in a catalytic converter?Diesel oxidation catalyst
Limits & alternatives
Engine type matters. Gasoline three-way catalysts face different exhaust conditions, and many formulations rely heavily on palladium and rhodium. Platinum can suffer sintering and inhibited activity under gasoline conditions; support design and alloying can help address these limitations.
Challenges and Opportunities for Platinum in the Modern Three-Way Catalyst
Part of a larger system
Catalytic cleanup changes pollutant molecules rather than removing the carbon from combustion. Carbon dioxide remains a product. At the material’s end of service, specialist recycling can recover precious metals for reuse in new catalysts and other applications.
Sources & further reading
- What metal is in a catalytic converter? ↗Johnson MattheyReference explanation · Source checked
- Diesel oxidation catalyst ↗Johnson MattheyTechnical documentation · Source checked
- Challenges and Opportunities for Platinum in the Modern Three-Way Catalyst ↗Johnson Matthey Technology ReviewTechnical documentation · Source checked
Sources and further reading. What the review labels mean