Diesel Oxidation Catalyst (DOC)

Product Specifications

Technical details and manufacturing context for Diesel Oxidation Catalyst (DOC)

Definition

The Diesel Oxidation Catalyst (DOC) is a critical component of the Exhaust Aftertreatment System in diesel engines. It uses a catalyst-coated substrate to facilitate chemical reactions that convert harmful pollutants—primarily carbon monoxide (CO) and unburned hydrocarbons (HC)—into less harmful carbon dioxide (CO₂) and water (H₂O) through oxidation. It also helps oxidize some particulate matter (soot) and plays a role in generating heat for downstream components like the Diesel Particulate Filter (DPF).

This component is typically installed in the exhaust line of diesel vehicles and machinery. Its core is a honeycomb-like substrate, either ceramic (cordierite) or metallic (stainless steel), coated with a washcoat containing precious metal catalysts such as platinum and palladium. The substrate is enclosed in a stainless steel canning (SS409/SS304) to ensure structural integrity and corrosion resistance.

Key specifications vary by application. The substrate diameter ranges from 143.8 to 304.8 mm, and length from 76.2 to 152.4 mm, matching standard exhaust pipe sizes. Cell density ranges from 200 to 400 cpsi, with wall thickness between 0.1 and 0.2 mm. The operating temperature range is 200–650°C; below 200°C light-off is not achieved, and above 650°C thermal aging occurs. Maximum continuous temperature is 650°C. Maximum exhaust flow rate is 300–1200 kg/h, and pressure drop at rated flow is ≤3 kPa. Conversion efficiency is ≥90% for CO and ≥80% for HC at operating temperature and space velocity. Precious metal loading is typically 30–70 g/ft³. Weight ranges from 5 to 20 kg.

These values are reference ranges; actual specifications must be confirmed for the specific model and application. The DOC is a component, not a standalone system, and its performance depends on integration with the engine and other aftertreatment devices. Always verify model-specific parameters and applicable standards with the legal manufacturer or supplier.

Working Principle

Exhaust gases flow through a honeycomb-like substrate (typically ceramic or metallic) coated with precious metal catalysts (like platinum, palladium). The catalyst lowers the activation energy required for oxidation reactions. At elevated exhaust temperatures, CO and HC react with oxygen (O₂) present in the exhaust stream to form CO₂ and H₂O. The substrate provides a large surface area for the reactions, while the washcoat (alumina, ceria) enhances catalyst dispersion and stability. The process is exothermic, generating heat that can aid downstream components like the DPF. The operating temperature must be within 200–650°C to achieve efficient conversion without thermal damage.

Common Materials

Ceramic substrate (cordierite), Metallic substrate (stainless steel), Catalyst washcoat (alumina, ceria), Precious metal catalysts (platinum, palladium)

Technical Parameters

Parameter	Typical range	Notes & selection driver
Substrate Diameter	143.8–304.8 mm	Matches standard diesel exhaust pipe sizes
Substrate Length	76.2–152.4 mm	Determines catalyst volume and conversion efficiency
Cell Density	200–400 cpsi	Higher density increases surface area but may increase backpressure
Wall Thickness	0.1–0.2 mm	Thinner walls reduce backpressure and improve light-off
Operating Temperature Range	200–650 °C	Below 200°C light-off not achieved; above 650°C thermal aging
Maximum Continuous Temperature	650 °C	Exceeding may cause sintering of precious metals
Maximum Exhaust Flow Rate	300–1200 kg/h	Based on engine displacement and application
Pressure Drop at Rated Flow	≤3 kPa	Higher pressure drop reduces engine efficiency
Conversion Efficiency (CO)	≥90 %	At operating temperature and space velocity
Conversion Efficiency (HC)	≥80 %	At operating temperature and space velocity
Precious Metal Loading	30–70 g/ft³	Typically Pt/Pd; higher loading improves durability
Substrate Material	Cordierite	Low thermal expansion, high thermal shock resistance
Canning Material	SS409/SS304	Stainless steel for corrosion resistance
Weight	5–20 kg	Depends on substrate size and canning

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Catalyst Substrate
Provides a high-surface-area structure for catalyst coating and exhaust gas flow

Material: Cordierite ceramic or stainless steel
Catalyst Washcoat Part
High-surface-area layer (e.g., alumina) that holds the precious metal catalyst particles

Material: Alumina (Al₂O₃), ceria (CeO₂)
Catalyst (Active Material) Part
Precious metals that catalyze the oxidation reactions

Material: Platinum (Pt), Palladium (Pd)
Canister/Shell Part
Outer metal housing that contains and protects the substrate

Material: Stainless steel
Mat/Support Material Part
Holds the substrate in place inside the canister and provides thermal insulation

Material: Intumescent or non-intumescent ceramic mat

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Diesel Oxidation Catalyst (DOC).

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Exhaust Aftertreatment System

View system integration details

Manufacturers of Diesel Oxidation Catalyst (DOC)

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Frequently Asked Questions

What is the function of a Diesel Oxidation Catalyst?

The DOC oxidizes carbon monoxide (CO) and unburned hydrocarbons (HC) in diesel exhaust into carbon dioxide (CO₂) and water (H₂O), reducing harmful emissions. It also helps oxidize some particulate matter and generates heat for downstream components like the Diesel Particulate Filter (DPF).

What are the typical operating temperature ranges?

The typical operating temperature range is 200–650°C. Below 200°C, the catalyst does not achieve light-off, so conversion efficiency is low. Above 650°C, thermal aging can occur, potentially damaging the catalyst. The maximum continuous temperature is 650°C.

What materials are used in a DOC?

The substrate is typically ceramic (cordierite) or metallic (stainless steel). The catalyst washcoat contains alumina and ceria, and the precious metal catalysts are usually platinum and palladium. The canning material is stainless steel (SS409/SS304).

How do I verify the correct DOC for my application?

You must confirm model-specific parameters such as substrate diameter, length, cell density, precious metal loading, and operating temperature range with the legal manufacturer or supplier. These values vary based on engine displacement and application, and must match your exhaust system specifications.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

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pressure:	Max 2 bar pressure drop across catalyst, system pressure up to 5 bar
flow rate:	10-100,000 m³/h (based on engine size and application)
temperature:	200-650°C (light-off: 200-250°C, max continuous: 650°C)
space velocity:	20,000-100,000 h⁻¹ (typical for DOC applications)

Product Specifications

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