SCR catalysts

SCR (selective catalytic reaction) exhaust gas aftertreatment systems are used for exhaust gas purification in gas engines and ignition jet engines that run on biogas, natural gas, sewage gas, landfill- or mine gas, as well as in diesel engines. By adding a reducing agent (AdBlue), the nitrogen oxides (NO_x) are selectively converted to nitrogen (N₂) and water (H₂O). With the aid of an SCR dosing system, the reducing agent is fed from a tank to the injector and dosed in the direction of a mixing device in order to achieve an ideal mixing of ammonia with the exhaust gas flow in the exhaust gas system. At the same time, the SCR catalyst selectively converts formaldehyde. A downstream barrier catalyst additionally converts carbon monoxide and prevents the emission of ammonia.