A metal DOC (Diesel Oxidation Catalyst) uses a metal honeycomb substrate (typically FeCrAl alloy) instead of ceramic as the catalyst carrier. Like ceramic DOC, it is installed in the diesel exhaust system to oxidize harmful gaseous pollutants, but the metal substrate offers distinct advantages.

Core Function (same as ceramic DOC):

• Converts Carbon Monoxide (CO) into CO₂.
• Converts Unburned Hydrocarbons (HC) into CO₂ and H₂O.
• Oxidizes NO to NO₂ to enable passive DPF regeneration.
• Reduces diesel exhaust odour.

Why metal substrate?

• Ultra-thin walls (as low as 0.03 mm) allow higher cell densities (up to 1200 CPSI) with lower backpressure.
• High thermal conductivity enables faster light‑off (reaches operating temperature 30–45 seconds faster than ceramic).
• Superior thermal shock resistance – metal substrates are highly ductile and resist cracking under extreme temperature fluctuations.
• Mechanical strength – more resistant to vibration and impact, ideal for off‑road and heavy‑duty applications.
• Lightweight – metal substrates are typically 40–50% lighter than equivalent ceramic substrates.
• Shape flexibility – can be manufactured in nearly any shape (oval, racetrack, trapezoidal, etc.) to fit tight packaging.

Metal DOC catalysts are increasingly used in high‑performance, heavy‑duty, and off‑highway diesel applications where durability and fast warm‑up are critical.

The DOC works on the principle of catalytic oxidation. The honeycomb substrate is coated with a "washcoat" containing precious metal catalysts — typically Platinum (Pt) and Palladium (Pd) — which promote chemical reactions without being consumed themselves.

Chemical Reactions:

• CO + ½ O₂ → CO₂ (Carbon Monoxide to Carbon Dioxide)
• HC + O₂ → CO₂ + H₂O (Hydrocarbons to CO₂ and Water)
• NO + ½ O₂ → NO₂ (Nitric Oxide to Nitrogen Dioxide)

Operating Conditions:

• The DOC becomes active (light‑off) at temperatures around 200–250°C.
• Optimal conversion efficiency (over 90% for CO and HC) is achieved at 300–450°C.
• Excessive heat above 650°C can cause thermal degradation of the catalyst coating.

Critical Role in the System:

• By converting NO to NO₂, the DOC provides the oxidant needed for passive DPF regeneration, which burns off trapped soot at lower temperatures (around 300–350°C).
• It also protects the downstream SCR (Selective Catalytic Reduction) catalyst from HC and CO poisoning.

The main difference in DOC coatings lies in the precious metal loading (expressed in grams per cubic foot — g/cft) and the Pt:Pd ratio. Higher loadings and specific ratios are required to meet stricter emission standards.

Explanation:

• Euro 5 requires 20 g/cft (20 grams of precious metals per cubic foot of substrate volume) to achieve the required CO and HC conversion efficiency under the NEDC test cycle.
• Euro 6 requires a higher loading of 40 g/cft (40 grams per cubic foot) to meet the stricter real‑driving emission (RDE) requirements, ensuring the DOC remains effective over a wider range of operating conditions and throughout its lifetime.
• The 4:1 Pt:Pd ratio is a common formulation that balances cost (palladium is less expensive than platinum) while maintaining high oxidation activity and sulfur tolerance.

Higher loadings provide better durability, more consistent performance under variable temperatures, and longer service life — which is why Euro 6 demands twice the loading of Euro 5.

Both metal and ceramic DOC catalysts serve the same purpose — oxidising CO, HC, and NO. However, they differ significantly in substrate material and performance characteristics. The table below summarizes the key differences:

Key Takeaways:

• Metal DOC is preferred where fast warm‑up, low backpressure, and durability are critical — such as high‑performance engines, off‑road vehicles, and applications with frequent thermal cycling.
• Ceramic DOC is more cost‑effective and performs well in standard passenger car applications with stable operating conditions.

The choice between metal and ceramic depends on your specific application requirements, budget, and emission targets.

The following are our suggested reference rates. If you are unsure, please contact our staff.

• 20g/cft 400-500cpsi = Euro 5
• 30g/cft 300-500cpsi = Euro 5
• 40g/cft 200-500cpsi = Euro 5
• 30g/cft 300-500cpsi = Euro 6
• 40g/cft 200-500cpsi = Euro 6

These combinations of precious metal loading (g/cft) and cell density (CPSI) are typical benchmarks for achieving the specified Euro emission standard. The actual performance may vary depending on engine calibration, exhaust temperature profile, and other system components. For tailored recommendations, please consult our technical team.

We offer a 1‑year warranty on our ceramic DOC products from the date of purchase.

What is covered:

• Manufacturing defects in the ceramic substrate, such as cracks, broken walls, or structural failures that occur under normal use.
• Coating integrity for coated DOC (flaking or detachment of the washcoat).

What is NOT covered:

• Damage caused by improper installation (e.g., over‑torquing, incorrect orientation, or physical impact).
• Engine‑related issues (misfires, excessive oil consumption, or incorrect air‑fuel mixture) that lead to overheating or clogging.
• Fuel contamination (high‑sulfur fuel, biodiesel impurities, or additives that poison the catalyst).
• Thermal degradation due to sustained exhaust temperatures above 650°C.
• Normal wear and tear or soot loading beyond the filter's capacity.

Claim procedure: To make a warranty claim, please contact our support team with your order number, installation records, and clear photos of the defect. We will review each case individually.

We recommend professional installation and regular maintenance to ensure the DOC operates within its design parameters.

Installing a metal DOC catalyst requires careful attention to both mechanical and thermal factors. Metal substrates are more forgiving than ceramic in terms of brittleness, but they still need proper handling. Follow these guidelines for a successful installation:

Mounting Position:

• The DOC must be installed as close as possible to the engine (typically after the turbocharger) to ensure fast light‑off.
• It should be positioned before the DPF and before the SCR (if equipped).
• Ensure the flow direction arrow points toward the rear of the vehicle.

Mechanical Support & Housing:

• Metal substrates are less brittle than ceramic, but still require secure mounting to prevent fatigue failure.
• Use appropriate metal cans, mounting mats (if required), and brackets. Metal substrates often use a welded or brazed attachment to the housing, which provides excellent durability.
• Ensure the housing allows for thermal expansion — metal substrates expand more than ceramic, so adequate clearance is necessary.
• Use high‑temperature gaskets and sealing materials to prevent exhaust gas bypass.

Exhaust Pipe Preparation:

• Thoroughly clean the pipe ends to remove rust, carbon, and debris.
• If welding is required, use stainless steel filler material compatible with the exhaust material (typically 304 or 409 stainless).
• Fit new gaskets on all flanged connections — never reuse old gaskets.

Welding Considerations (for weld‑on units):

• Metal DOC substrates can withstand higher welding temperatures than ceramic, but avoid excessive heat input to prevent distortion of the thin metal foils.
• Use TIG or MIG welding with appropriate settings. Tack‑weld in several positions before final welding.
• Allow the welds to cool slowly to avoid thermal stress.

Sensor Connections:

• If the DOC has integrated temperature sensors or NOx sensors, ensure they are correctly connected to the ECU.
• Route sensor wiring away from hot exhaust components and moving parts.

Post‑Installation Testing:

• Start the engine and check for exhaust leaks around all connections.
• Allow the engine to reach operating temperature and monitor the DOC's performance via diagnostic tools (exhaust gas temperature, backpressure, and NOx/CO readings).
• Perform a test drive under various load conditions to confirm the catalyst reaches light‑off temperature and operates correctly.

Our shipping and delivery times depend on stock availability:

• If we have stock: We ship within 1–3 business days. Delivery typically takes 12–15 days (including customs clearance and duties).
• If we are out of stock: Production and handling take 15–20 business days, then delivery takes approximately 12–15 days (including customs clearance and duties).

All shipments are sent DDP (Delivered Duty Paid) – this means that all customs clearance fees, import duties, and taxes are already included in the total price you pay. You will not be charged any extra fees upon delivery.

If you need faster delivery, please contact us to arrange expedited shipping via DHL, UPS, or FEDEX (additional charges apply).

We will provide you with a tracking number as soon as your order is dispatched.

You can reach our team directly via WhatsApp or email. We are happy to assist with any questions about products, sizing, orders, or technical support.

We typically respond within 24 hours (Monday–Saturday). Please include your order number or vehicle details for faster assistance.

Our company headquarters is located at:

Building C, Zhongguan Innovation Center, Dongcheng 2nd Road, Pujiang Town, Minhang District, Shanghai, China

We welcome business visits by appointment. Please contact us in advance to arrange a suitable time.