So what is a catalytic converter made of? The catalyst inside a catalytic converter is made typically from platinum or a similar metal, such as rhodium or palladium. Gases flow through a ceramic honeycomb structure located within the cat housing. This is lined with metals that have specific jobs that play a role in reducing emissions. There are two main types of catalysts that might be featured in a car:

• Reduction catalysts: Help reduce nitrogen oxide pollution by removing oxygen. Nitrogen oxides are broken up into nitrogen and oxygen gases, which on their own are harmless.
• Oxidation catalysts: Used to change carbon monoxide into carbon dioxide through an opposite process of adding oxygen. 

Also located near the catalytic converter is an oxygen (O2) sensor, which works to tell a car’s electronic control unit (ECU) how much oxygen is found in the exhaust gases. This helps a vehicle run on a more efficient air/fuel ratio, allowing the engine to supply the converter with enough oxygen to complete the oxidation process.