What Precious Metals Can Be Extracted from a Car's Catalytic Converter?

[DelCayden]

The catalytic converter can extract platinum group metals. A car's catalytic converter contains many precious metals. The catalytic converter is used to purify exhaust gases, and this component is installed at the front section of the exhaust pipe. If a car has two front sections of the exhaust pipe, it may have two or even more catalytic converters. Without a catalytic converter, the toxic and harmful substances in the car's exhaust would exceed the standard, polluting the environment. The catalytic converter has an oxygen sensor at both the front and rear. The front oxygen sensor is called the upstream oxygen sensor, while the rear one is called the downstream oxygen sensor. The main function of the upstream oxygen sensor is to detect the oxygen content in the exhaust. The sensor can feed this data back to the ECU, which then adjusts the air-fuel ratio accordingly. The air-fuel ratio is a crucial parameter for the engine. The downstream oxygen sensor primarily checks whether the catalytic converter has failed. If the data fed back to the ECU by both sensors is the same, it indicates that the catalytic converter has failed. Upon failure, a warning light will illuminate on the car's dashboard to alert the driver. Meaning of ECU: ECU (Electronic Control Unit), also known as the "vehicle computer" or "onboard computer," is a specialized microcomputer controller for automobiles. Like a regular computer, it consists of a microprocessor (CPU), memory (ROM, RAM), input/output interfaces (I/O), analog-to-digital converters (A/D), and other large-scale integrated circuits for shaping and driving. In simple terms, "the ECU is the brain of the car." After the catalytic converter fails: If the temperature is too high, the catalytic converter cannot function at normal temperatures. Its catalyst must be heated to a certain temperature to gain oxidation or reduction capabilities. Typically, the catalytic converter's light-off temperature is 250-350°C, and its normal operating temperature is 400-800°C. Chronic poisoning: The catalyst is highly sensitive to elements like sulfur, lead, phosphorus, and zinc. Sulfur and lead come from gasoline, while phosphorus and zinc come from lubricating oil. These four substances and their oxide particles formed during engine combustion easily adsorb onto the catalyst's surface, preventing it from contacting exhaust gases and thus losing its catalytic function—a phenomenon known as "poisoning." Carbon buildup: When the car operates at low temperatures for extended periods, the catalytic converter cannot activate, and soot from the engine exhaust adheres to the catalyst's surface, blocking contact with CO and HC. Over time, the carrier's pores become clogged, reducing its conversion efficiency. Exhaust deterioration: The catalytic converter has a limited capacity for pollutant conversion. Therefore, built-in purification technology must minimize the original exhaust pollutants. If the concentration and total amount of exhaust pollutants are too high—such as when the air-fuel mixture is too rich—it can impair the catalytic converter's conversion ability and efficiency. Oxygen transmission failure: To achieve optimal exhaust catalytic efficiency (over 90%), an oxygen sensor must be installed in the engine's exhaust pipe for closed-loop control. The oxygen sensor measures the oxygen concentration in the exhaust, converts it into an electrical signal, and sends it to the ECU, thereby keeping the engine's air-fuel ratio within a narrow, near-ideal range.