Selective Catalytic Reduction

Selective catalytic reduction (SCR) is an advanced emissions control technology used in diesel engines to reduce the amount of nitrogen oxides (NOx) released into the atmosphere.

SCR works by injecting a liquid reductant, typically aqueous urea solution, into the engine’s exhaust system. The exhaust gas then passes over a catalytic converter that contains a special catalyst material, usually based on vanadium or titanium, which converts the NOx into nitrogen gas (N2) and water vapor (H2O). The urea solution reacts with the NOx in the presence of the catalyst, creating ammonia (NH3), which then reduces the NOx into N2 and H2O.

SCR is an effective technology for reducing NOx emissions, which are a major contributor to air pollution and can have harmful effects on human health and the environment. SCR systems can reduce NOx emissions by up to 90%, and are commonly used in heavy-duty diesel vehicles, such as trucks and buses, as well as in power plants and other industrial applications.

An SCR (Selective Catalytic Reduction) system is a system installed on diesel vehicles to reduce harmful Nitrous Oxide (NOx) emissions. It works by injecting an automotive grade urea, or Diesel Exhaust Fluid (DEF) through a specially designed catalyst, into the exhaust stream of a diesel engine.

Why is SCR selective?

SCR technology is designed to permit nitrogen oxide (NOx) reduction reactions to take place in an oxidizing atmosphere. It is called “selective” because it reduces levels of NOx using ammonia as a reductant within a catalyst system.

What is the common reductant used in the selective catalytic reduction SCR system?

SCR uses ammonia as a reducing agent. Ammonia is introduced into the exhaust stream from a combustor. It reduces the levels of NOx within a catalyst system.

What is selective catalytic reduction?

Selective Catalytic Reduction (SCR) is an advanced active emissions control technology system that reduces tailpipe emissions of nitrogen oxides (NOx) down to near-zero levels in newer generation diesel-powered vehicles and equipment.

An SCR system uses aqueous ammonia to convert harmful components (NOx) into harmless gasses in the exhaust. In most cases we use AUS40 or AdBlue. AdBlue is the brand name for a urea solution that contains 32.5% urea in demineralised water. The technical name is AUS32.

What is the difference between DPF and SCR?

A DPF’s core can be made of a few different materials but the most common are cordierite composites. An SCR catalyst has valuable filter contents in the form of ceramic materials and precious metals. Additionally, SCR utilizes a consumable (Diesel Exhaust Fluid) whereas DPF must be regenerated, usually done automatically when driving at highway speeds.

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