The process of purification and production of SCR urea

Automotive urea is an aqueous urea solution with a concentration of 32.5% and a solvent of ultrapure water. The key point is the purity of the raw material, which is produced from urea crystals and ultrapure water. From the point of view of production process, although the automotive urea requirements for raw material purity is higher than the general industrial demand, but the current domestic process can already meet the actual application needs. The production process of automotive urea is not enough to build high barriers to entry.

Domestic automotive urea is mainly purified from industrial urea, its main principle is: 1) at a temperature of 70-75 ℃, urea in aqueous solution hydrolysis. 2) at a temperature of 30 ℃ or less, urea re-crystallized from the aqueous solution. 3) each hydrolysis crystallization once, its purity will be significantly improved, generally using industrial grade urea hydrolysis crystallization once, it can reach the standard requirements of automotive urea, its The output ratio is 1.5:1.

Automotive urea must use the electronic industry first-class ultrapure water. Due to the SCR catalyst carrier is very prone to metal ion poisoning and thus lose the catalytic effect, so the automotive urea solution must use the first grade ultra-pure water (resistivity ≥ 18MΩ?cm) from the electronics industry. The automotive urea solution will start to freeze at -11℃, and in actual use it will freeze completely at -20℃. The current technology is to prevent the solution from freezing by adding modifiers to lower the freezing point of the solution and by adding heating devices.

Automotive urea solution (AdBlue) is a solution prepared with high purity urea without any other additives and pure water, and the urea content in the solution is 32.5% (mass fraction). Most domestic and foreign heavy-duty diesel engine manufacturers use SCR (Selective Catalytic Reduction) technology to meet the requirements of Euro IV and Euro V motor vehicle emission standards. Vehicles that choose SCR technology must add urea solution as catalytic reducer to make the vehicle meet the emission standards