The conversion of nitrogen oxides (NOX) of a SCR system highly depends on the availability of ammonia (NH3) generated from the injected AdBlue® (32.5% aqueous urea solution). The release of NH3 is a chemical process which is dependent on temperature and the available time in order to convert the urea ((NH2)2CO) solution completely to ammonia (NH3). This reaction occurs in multiple, subsequent steps.
1. Evaporation of water
[(NH2)2CO•7H2O] → [(NH2)2CO] + 7H2O
2. Thermolysis of urea
[(NH2)2CO] → NH3 + HNCO
3. Hydrolysis of isocyanic acid
HNCO + H2O → NH3 + CO2
Low temperatures and short reaction times – especially in combination with high dosing rates of urea – lead to the formation of undesired solid by-products (e.g. cyanuric acid) which block the exhaust gas aftertreatment system and cannot be vaporized again during the standard operation conditions of combustion engines.
4. Formation of cyanuric acid
3 HNCO → [(HNCO)3]solid
The unique hydrolysis catalyst technology of INTERKAT enables our customers to achieve complete conversion of urea into ammonia even in difficult conditions and avoid the risk of blockage due to residues e.g. cyanuric acid. With this technology, ammonia can be supplied at significantly lower temperatures, offering you the possibility to design an effective low temperature SCR system which will become mandatory for future emission legislation. INTERKAT hydrolysis technology can be used for different types of catalyst substrates (e.g. electrically heated catalysts) but also as a coating on specific component parts of the exhaust system.
“INTERKAT will always provide the optimal catalyst for your application”