The exhaust gas of diesel engines mainly contains nitrogen oxides, soot particles, and sulfur dioxide, while three-way catalytic converters mainly oxidize carbon monoxide, nitrogen oxides, and hydrocarbons, and cannot catalyze the nitrogen oxides and soot particles generated by diesel engines in large quantities. Moreover, ordinary three-way catalytic converters cannot withstand the high temperature and high pressure environment of diesel engines.
Working principle of three-way catalytic converter
The three-way catalytic converter converts carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) in car exhaust into harmless gases, including carbon dioxide (CO2), water, and nitrogen (N2), through the action of a catalyst. The specific process is as follows:
Carbon monoxide (CO): It is oxidized to carbon dioxide (CO2) at high temperatures.
Hydrocarbons (HC): are oxidized to water and carbon dioxide (H2O and CO2) at high temperatures.
Nitrogen oxides (NOx): reduced to nitrogen gas (N2) and water (H2O).
Structure and Materials of Three way Catalytic Converter
A three-way catalytic converter typically contains a layer of precious metal catalysts such as platinum (Pt), rhodium (Rh), and palladium (Pd), which are coated on a porous ceramic support. The catalyst itself does not participate in the reaction, but accelerates the chemical reaction by providing active sites.
Alternative Technologies for Diesel Vehicles
Although diesel vehicles do not have three-way catalytic converters, some technologies can replace or assist in reducing emissions. For example, the four effect catalytic technology integrates a carbon particulate trap, a urea lean NOx catalyst, and a diesel oxidation catalyst, which can effectively address the emission issues of diesel vehicles
