SCR Catalyst for Diesel Engines | NOx Reduction Component

Product Specifications

Technical details and manufacturing context for Selective Catalytic Reduction (SCR) Catalyst

Definition

The Selective Catalytic Reduction (SCR) Catalyst is a component used in the exhaust aftertreatment systems of diesel and lean-burn engines. Its primary function is to reduce nitrogen oxides (NOx) in exhaust gas to harmless nitrogen (N₂) and water (H₂O) through a chemical reaction with a reductant, typically ammonia derived from a urea solution (AdBlue/DEF). This process is essential for meeting stringent emissions regulations. The catalyst is typically a honeycomb or substrate structure coated with active materials such as vanadium pentoxide (V₂O₅) on a titanium dioxide (TiO₂) substrate, or copper-zeolite or iron-zeolite formulations. During operation, a urea-water solution is injected into the exhaust stream upstream of the catalyst. The solution decomposes into ammonia (NH₃), which then reacts with NOx on the catalyst's active sites, selectively reducing it to nitrogen and water vapor. The catalyst operates effectively within a temperature range of 250–450°C; below 250°C, conversion efficiency drops, and above 450°C, the catalyst may sinter. Space velocity typically ranges from 10,000 to 60,000 h⁻¹, with higher values reducing NOx conversion. At optimal conditions, NOx conversion efficiency can reach 90–98%. The NH₃/NOx ratio should be maintained between 0.8 and 1.2, with a stoichiometric ratio of 1.0; higher ratios may cause ammonia slip. The catalyst is available in various sizes, with diameters typically 150–300 mm and lengths 300–600 mm, and can be customized. Cell density ranges from 200 to 400 cpsi, and wall thickness from 0.15 to 0.30 mm. Pressure drop is typically 1–5 kPa at rated flow, and excessive pressure drop can affect engine performance. The catalyst has a sulfur tolerance of ≤50 ppm, as higher sulfur levels deactivate the catalyst. Mechanical strength is ≥1.5 MPa, and weight ranges from 5 to 20 kg depending on size and substrate material. For specific applications, verify model-specific values and standards with the legal manufacturer or supplier.

Working Principle

Exhaust gas containing NOx passes over the catalyst surface. A urea-water solution is injected upstream, decomposing into ammonia (NH₃). On the catalyst's active sites, ammonia reacts with NOx in a selective catalytic reduction reaction, forming nitrogen and water vapor. Common catalyst formulations include vanadium-based or zeolite-based materials.

Common Materials

Vanadium Pentoxide (V₂O₅) on Titanium Dioxide (TiO₂) substrate, Copper-Zeolite or Iron-Zeolite

Technical Parameters

Parameter	Typical range	Notes & selection driver
Operating Temperature	250–450 °C	Below 250°C, conversion efficiency drops; above 450°C, catalyst may sinter.
Space Velocity	10000–60000 h⁻¹	Higher space velocity reduces NOx conversion.
NOx Conversion Efficiency	90–98 %	At optimal temperature and NH3/NOx ratio.
NH3/NOx Ratio	0.8–1.2	Stoichiometric ratio is 1.0; higher ratio may cause NH3 slip.
Dimensions (Diameter)	150–300 mm	Custom sizes available.
Dimensions (Length)	300–600 mm	Custom sizes available.
Cell Density	200–400 cpsi	Higher cell density increases surface area but may increase pressure drop.
Wall Thickness	0.15–0.30 mm	Thinner walls reduce pressure drop.
Pressure Drop	1–5 kPa	At rated flow; excessive pressure drop affects engine performance.
Sulfur Tolerance	≤50 ppm	Higher sulfur deactivates catalyst.
Mechanical Strength	≥1.5 MPa	Resistance to crushing and vibration.
Weight	5–20 kg	Depends on size and substrate material.

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 ceramic or metallic honeycomb structure to support the active catalytic coating.

Material: Cordierite ceramic or metallic alloy (e.g., FeCrAl)
Washcoat Part
A porous layer applied to the substrate to increase surface area and anchor the active catalytic material.

Material: Alumina (Al₂O₃), Titanium Dioxide (TiO₂)
Active Catalytic Material Part
The chemical compound that catalyzes the SCR reaction between NOx and ammonia.

Material: Vanadium Pentoxide (V₂O₅), Copper-Zeolite (Cu-Zeolite)
Catalyst Canning / Housing
Metal shell that contains and protects the catalyst brick, ensuring proper gas flow and mechanical integrity.

Material: Stainless steel

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Selective Catalytic Reduction (SCR) Catalyst.

Applied To / Applications

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

Exhaust Aftertreatment System

View system integration details

Manufacturers of Selective Catalytic Reduction (SCR) Catalyst

Manufacturer profiles associated with Selective Catalytic Reduction (SCR) Catalyst.

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Frequently Asked Questions

What is the operating temperature range for this SCR catalyst?

The typical operating temperature range is 250–450°C. Below 250°C, conversion efficiency drops, and above 450°C, the catalyst may sinter. Always verify the exact range for your specific application with the manufacturer.

What reductant is used with this catalyst?

The reductant is typically ammonia derived from a urea solution (AdBlue/DEF). The solution is injected upstream of the catalyst and decomposes into ammonia, which reacts with NOx.

What is the expected NOx conversion efficiency?

At optimal temperature and NH3/NOx ratio, the NOx conversion efficiency is typically 90–98%. Actual efficiency depends on operating conditions and system design.

What are the common catalyst formulations?

Common formulations include vanadium pentoxide (V₂O₅) on a titanium dioxide (TiO₂) substrate, and copper-zeolite or iron-zeolite materials. The choice depends on the application and operating conditions.

Data Basis

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Preliminary Technical Classification

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pressure:	Up to 10 bar (typical 1-5 bar)
flow rate:	0.5-50 m/s gas velocity
temperature:	250-450°C (optimal 300-400°C)
space velocity:	5000-30000 h⁻¹ (typical 15000-25000 h⁻¹)
ammonia to nox ratio:	0.8-1.2 (optimal 1.0)

Selective Catalytic Reduction (SCR) Catalyst

Product Specifications

Industry Taxonomies & Aliases

Applied To / Applications

Industrial Ecosystem & Supply Chain Structure

Application Fit & Sizing Matrix

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