Name AnalysisMetal DOC:Metal: refers to the carrier material of the catalyst as metal (such as honeycomb metal substrate), which is different from the traditional ceramic carrier (such as cordierite).DOC: Diesel Oxidation Catalyst, which reduces harmful pollutants in exhaust gas through oxidation reaction. CharacteristicsMaterial characteristics:Metal substrate: usually adopts high temperature resistant alloy (such as iron chromium aluminum fiber), with high mechanical strength and impact resistance.Coating: The surface is coated with active catalytic materials (such as platinum, palladium and other precious metals) to promote oxidation reaction.Structural characteristics:High porosity design: The metal carrier can be made into a thinner wall and denser honeycomb structure to reduce back pressure.Quick ignition: Metal has good thermal conductivity and can quickly reach the temperature required for catalytic reaction.Environmental adaptability:High temperature resistance (up to 1000°C or more), better thermal shock resistance than ceramic carrier. FunctionsCore functions: Convert harmful components in exhaust gas through catalytic oxidation reactions:Hydrocarbons (HC) → Oxidized to H₂O and CO₂.Carbon monoxide (CO) → Oxidized to CO₂.Particulate matter (PM): Some soluble organic matter (SOF) is oxidized to reduce PM emissions.NO: A small amount of NO is oxidized to NO₂ (to provide support for subsequent SCR or DPF regeneration).Auxiliary functions:Provide NO₂ to DPF (diesel particulate filter) to promote passive regeneration (NO₂ oxidizes soot particles).Reduce exhaust odor (oxidized sulfides, etc.). AdvantagesPerformance advantages:High efficiency and low temperature activity: Metal has fast thermal conductivity and ignites faster during cold start (especially in short-distance driving in cities).Low back pressure: The flow channel design of the metal carrier is more flexible, reducing engine power loss.Long life: Resistant to mechanical vibration and thermal shock, suitable for harsh working conditions (such as construction machinery and commercial vehicles). Application advantages:Compact design: The metal carrier can be made into a special-shaped structure to adapt to vehicles with limited space.Strong compatibility: It can be integrated with post-treatment systems such as SCR and DPF.Maintenance advantages:Not easy to break, strong resistance to sulfur poisoning (depending on the catalyst formula).