Why Are Three-Way Catalytic Converters So Expensive?
1 Answers
The high cost of three-way catalytic converters is due to the presence of precious metals in their honeycomb-structured substrate. Below are specific details about common failures of three-way catalytic converters: 1. Overheating: At normal temperatures, three-way catalytic converters do not possess catalytic capabilities. Their catalysts must be heated to a certain temperature to gain oxidation or reduction abilities. Typically, the light-off temperature for catalytic converters ranges between 250–350°C, while their normal operating temperature is generally between 350–700°C. During operation, higher-quality catalytic converters generate more heat, and oxidation temperatures also rise. When temperatures exceed 850–1000°C, the catalyst coating inside may detach, and the substrate can crack. 2. Chronic Poisoning: The catalysts are highly sensitive to elements such as sulfur, lead, phosphorus, and zinc. Sulfur and lead come from gasoline, while phosphorus and zinc originate from lubricating oil. These four substances, along with their oxide particles formed during engine combustion, easily adhere to the catalyst's surface, preventing contact with exhaust gases and thereby losing catalytic effectiveness—a phenomenon known as 'poisoning.' 3. Carbon Buildup: When a vehicle operates under low-temperature conditions for extended periods, the three-way catalytic converter cannot activate. Carbon deposits from the engine exhaust will accumulate on the catalyst's surface, blocking contact with CO and HC. Over time, this leads to clogged substrate pores, reducing conversion efficiency.
