AdBlue

AdBlue is an aqueous urea solution consisting of 32.5% by mass of pure urea and demineralised water. It is used to reduce nitrogen oxide emissions from diesel engines in vehicles. The solution is non-toxic and has been standardised internationally.

Definition
AdBlue is a specific AUS (Aqueous Urea Solution) 32, which is used as an environmentally friendly technology to reduce nitrogen oxide emissions from diesel engines. It is injected via a dosing unit upstream of an SCR catalytic converter to enable the conversion of nitrogen oxides into nitrogen and water.

Background / Origin
AdBlue is a trade name protected by the German Association of the Automotive Industry (VDA). The compounds that make up AdBlue are produced through a chemical process. The solution has been in use since the introduction of the Euro 4 and Euro 5 emissions standards to comply with strict environmental regulations. AdBlue is a mandatory standard in numerous regions, although it is known as Diesel Exhaust Fluid (DEF) in North America and as Arla 32 in South America.

The technology has continued to evolve, meaning that an increasing number of cars and lorries are now fitted with SCR catalytic converters to reduce emissions. The development of the AdBlue infrastructure has included the provision of dispensers at petrol stations across Europe since 2020.

Properties
AdBlue has the following key properties:

- Composition: AdBlue consists of 32.5% by mass of pure urea and demineralised water.
- Physical characteristics: The solution is colourless, odourless and non-toxic.
- Chemical properties: AdBlue is injected at high pressure into the exhaust system by a metering pump, where it is converted into ammonia via an intermediate step.

The addition of urea, in conjunction with SCR catalysts, enables nitrogen oxide emissions to be reduced by up to 90 per cent.

Application and market significance
AdBlue is predominantly used in diesel vehicles and is crucial for compliance with emissions standards. The use of SCR technology makes it possible to significantly reduce nitrogen oxide emissions by injecting AdBlue into the exhaust stream. AdBlue consumption accounts for between 2% and 8% of diesel fuel consumption.

AdBlue is produced by around 150 manufacturers worldwide, ensuring wide availability even as sales volumes rise. The VDA study shows that around 20 million diesel vehicles equipped with AdBlue technology are expected to be in operation in Europe by 2020.

Distinction from similar terms
AdBlue differs from other urea solutions in that it was developed specifically for use in SCR systems. Unlike Diesel Exhaust Fluid (DEF), the term ‘AdBlue’ is a registered trademark and refers to a precisely defined formulation.

Summary
AdBlue is a standardised aqueous urea solution used to reduce nitrogen oxide emissions in diesel engines. Comprising 32.5% urea and demineralised water, it is integrated into vehicles via SCR catalytic converters. The solution helps ensure compliance with strict emissions standards and has become a widely adopted technology in the automotive market. Furthermore, AdBlue is produced by numerous manufacturers worldwide, ensuring reliable availability.