What does a catalytic converter do?
A catalytic converter (often referred to as a "cat") is part of your car's exhaust system, a metal canister that measures between 10-14" long, generally located near the exhaust outlet. Vehicles with combustion engines emit ‘smog,' which is composed predominantly of hydrocarbons, nitrogen oxides and carbon monoxide. Catalytic converters can reduce up to 90% of a vehicle's harmful emissions and convert them to carbon dioxide, water vapor, nitrogen and oxygen, which are less harmful gasses.
How do catalytic converters work?
Catalytic converters work by filtering vehicle emissions through a chamber containing two catalysts, ceramic substrates coated in three rare earth metals: palladium, platinum and rhodium. The substrates, which look like a honeycomb, maximize the surface area available for conversion and help retain the high temperature (at least 400°F) required for conversion to take place. As exhaust passes through the catalytic converter, the interaction of emissions, heat and precious metals changes the anatomic structure of the exhaust emissions and converts them to gasses and water vapor. The first stage of the catalytic converter is the reduction catalyst, which uses platinum and rhodium to reduce nitrogen oxide to nitrogen and oxygen. The second stage, the oxidation catalyst, reduces hydrocarbons and carbon monoxide by burning them as they pass through the second substrate. Remaining gasses are then passed through the rest of the vehicle exhaust system.
Am I required to have a catalytic converter?
Catalytic converters have been required on all vehicles since 1975, and without one, your vehicle won't pass the emissions tests required for driving it legally. If you own a vehicle long enough, they will eventually need to be replaced, but they usually last at least ten years. Unfortunately, because catalytic converters contain precious metals, they can be expensive to replace and are a prime target for theft. There are measures you can take to protect your catalytic converter, such as alarm systems and security shields that make it much more difficult for someone to remove the catalytic converter without your knowledge.