Abstract: A process for catalytic removal of a pollutant from a combustion installation exhaust gas includes calculating, from operationally relevant parameters of the installation, a pollutant concentration using a predetermined characteristic diagram. A predetermined quantity of a reagent is introduced into the exhaust per unit time as a function of the calculated pollutant concentration, the reagent reacting with the pollutant at a catalytic converter. Operating states of the installation with substantially constant pollutant emission levels are determined. The pollutant concentration during an operating state of the installation with a substantially constant pollutant emission level is determined with a sensor and only a pollutant concentration from the installation in a steady operating state is used to correct the diagram. The pollutant concentration from the installation is calculated with the diagram in a non-steady operating state.

Abstract: A completely self-contained device reduces the NOx content in the exhaust gas of an internal combustion engine operated with excess air. One or more reduction catalytic converters working according to the SCR principle are provided. A reducing agent control unit need not make any recourse to data present in the control unit of the internal combustion engine. Fitting and retrofitting to a vehicle is greatly simplified, particularly for vehicles that are already in use.