What is inside a three-way catalytic converter?
2 Answers
A three-way catalytic converter consists of four main components: the shell, vibration damping layer, substrate, and catalyst coating. The specific details about the three-way catalytic converter are as follows: 1. Metals contained in the three-way catalytic converter: Platinum is one of the metals found in automotive three-way catalytic converters. Other metals include cerium, copper, iron, manganese, nickel, palladium, and rhodium. The content of these metals varies depending on the vehicle model and production batch. However, the content of platinum, palladium, and rhodium determines the recycling value of the automotive three-way catalytic converter. 2. The three-way catalytic converter is a crucial external purification device in the automotive exhaust system: It converts harmful gases such as CO, HC, and NOx from vehicle exhaust into harmless carbon dioxide, water, and nitrogen through oxidation and reduction reactions. Since the three-way catalytic converter can simultaneously convert the three main harmful substances in exhaust gases into harmless substances, it is called 'three-way.' 3. Working principle of the three-way catalytic converter: When high-temperature vehicle exhaust passes through the purification device, the catalyst in the three-way catalytic converter enhances the activity of CO, HC, and NOx gases, promoting specific oxidation-reduction chemical reactions. This process transforms the three harmful gases into harmless ones, thereby purifying the vehicle exhaust.
The internal structure of the catalytic converter is quite intricate, as I've seen from disassembled units. The core component is a honeycomb-shaped ceramic block, densely packed with tiny channels to ensure exhaust gases flow evenly. It's coated with precious metals like platinum, palladium, and rhodium as catalysts. Though their content is just a fraction of a gram, they play a crucial role. These metals facilitate chemical reactions at high temperatures, converting harmful carbon monoxide, hydrocarbons, and nitrogen oxides in the exhaust into harmless carbon dioxide, water, and nitrogen. The exterior is protected by a stainless steel shell with added insulation to prevent heat loss. Modern vehicles also feature front and rear oxygen sensors to monitor conversion efficiency in real-time. This component is highly sensitive to fuel quality—using substandard gasoline can poison these precious metals, rendering them ineffective.
