Is Automotive Exhaust Fluid Urea?
2 Answers
Automotive exhaust fluid is urea, an essential consumable in SCR technology. The formal name for automotive exhaust fluid is Diesel Exhaust Fluid (DEF). If DEF is not loaded, or if its purity is insufficient or its quality is substandard, the vehicle's engine will automatically reduce speed. Additionally, low-quality DEF can contaminate the catalyst in the SCR catalytic reaction tank, leading to severe consequences. Automotive exhaust fluid utilizes SCR technology to reduce nitrogen oxide emissions from diesel vehicles. The SCR system includes a urea tank (which holds DEF) and an SCR catalytic reaction tank. When nitrogen oxides are detected in the exhaust pipe during SCR system operation, the urea tank automatically sprays DEF. The DEF and nitrogen oxides undergo a redox reaction in the SCR catalytic reaction tank, producing harmless nitrogen gas and water vapor, which are then expelled.
Yes, automotive exhaust fluid is indeed urea, but not the ordinary fertilizer urea. It's a specially formulated urea solution. The ones I've used are called AdBlue, which is a mixture of urea and water, specifically about 32.5% crystalline urea and 67.5% deionized water. It's mainly used in diesel vehicles, stored in a small tank on the vehicle, to treat harmful substances in the exhaust, such as nitrogen oxides. Through selective catalytic reduction technology, the urea decomposes into ammonia when heated, reacting with the exhaust to produce harmless nitrogen and water, reducing pollution. I remember that using the wrong type is not acceptable—pure urea is corrosive and requires a specially formulated liquid; otherwise, it can damage the catalytic converter, leading to major issues. This is common in European diesel vehicles, and now Chinese regulations also mandate its use to help reduce emissions and be more environmentally friendly. When refilling, it's important to go to official gas stations or 4S shops and avoid mixing it with other liquids to ensure the engine runs smoothly.
