Catalytic Coating

Catalytic coating is a critical component in diesel particulate filters (DPFs) and gasoline particulate filters (GPFs) that facilitates the oxidation of captured soot particles and reduces harmful emissions. This coating typically contains precious metals like platinum, palladium, or rhodium deposited on a ceramic or metallic substrate. It operates at high temperatures (typically 250-600°C) to enable continuous regeneration of the filter by converting carbonaceous particulate matter into carbon dioxide, while also reducing nitrogen oxides (NOx), carbon monoxide (CO), and unburned hydrocarbons (HC) through redox reactions.

The catalytic coating functions through heterogeneous catalysis where precious metal active sites on the substrate surface adsorb exhaust gas molecules. Oxygen molecules dissociate on the catalyst surface, creating active oxygen species that oxidize carbon particles (soot) to CO2. Simultaneously, reduction reactions convert NOx to N2 and O2, while oxidation reactions transform CO and HC to CO2 and H2O. The coating's porous structure maximizes surface area for reactions while maintaining gas flow through the filter.