Does Every Car Have a Three-Way Catalytic Converter?
2 Answers
Not all cars are equipped with a three-way catalytic converter. In the early years in China, vehicles produced that did not meet the National II emission standards lacked this component. The three-way catalytic converter is an external purification device installed in the vehicle's exhaust system. It converts harmful gases such as CO emitted from the car's exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. Below are the reasons for the failure of a three-way catalytic converter: Excessive Temperature: At room temperature, the three-way catalytic converter does not possess catalytic capabilities. Its catalyst must be heated to a certain temperature to gain oxidation or reduction abilities. Typically, the light-off temperature of the catalytic converter ranges between 250–350 degrees Celsius, with normal operating temperatures generally between 400–800 degrees Celsius. During operation, the catalytic converter generates a significant amount of heat, and higher loads result in higher oxidation temperatures. When the temperature exceeds 1,000 degrees Celsius, the catalyst coating inside can sinter and fail, also increasing the risk of vehicle fires. Therefore, it is crucial to control factors that cause exhaust temperature to rise, such as delayed ignition timing, misfiring, or incorrect ignition sequences, as these allow unburned fuel mixture to enter the catalytic converter, leading to excessively high exhaust temperatures and impairing its efficiency. Chronic Poisoning: The catalyst is highly sensitive to elements such as sulfur, lead, phosphorus, and zinc. Sulfur and lead originate from gasoline, while phosphorus and zinc come from lubricating oil. These four substances, along with their oxide particles formed during combustion in the engine, tend to adhere to the catalyst's surface, preventing it from contacting exhaust gases and thus losing its catalytic function—a phenomenon known as poisoning. Carbon Buildup: When a car operates under low-temperature conditions for extended periods, the three-way catalytic converter cannot activate, and carbon particles from the engine exhaust adhere to the catalyst's surface. This prevents contact with CO and HC, eventually clogging the converter's pores and reducing its conversion efficiency. Exhaust Deterioration: The catalytic converter has a limited capacity for pollutant conversion, so it is essential to minimize raw emissions through internal purification technologies. If the concentration or total volume of exhaust pollutants is too high—such as an overly rich air-fuel mixture—it can impair the catalytic converter's ability to transform pollutants, lowering its efficiency. Additionally, when excessive amounts of HC and CO enter the catalytic converter, they trigger intense oxidation reactions, generating excessive heat that can damage the converter due to overheating.
That depends on the situation, not every car has a catalytic converter. The catalytic converter is mainly used in gasoline-powered vehicles, specifically designed to treat harmful nitrogen oxides, carbon monoxide, and hydrocarbons in the exhaust, converting them into harmless substances like carbon dioxide and water. But diesel vehicles don't have this; they usually install diesel particulate filters to control emission pollution. As for electric vehicles, forget about it—they rely entirely on batteries, have no internal combustion engine, and thus don't need a catalytic converter. Older cars, like those from before the 1970s or 1980s, might lack this component since regulations weren't strictly enforced back then. Nowadays, with stricter global environmental regulations, new cars are generally required to have one, but there are still a few older models in the used car market on the road—so be careful. When we repair cars, we often encounter issues with clogged or failed catalytic converters. It's recommended to check them during regular maintenance to avoid regretting it only after the exhaust exceeds standards.
