Process for conducting and testing the activity of a nitrogen oxides storage catalyst comprises comparing the ageing factor of the catalyst with a number of threshold values of different levels

摘要

The activity of a NOx storage catalyst is conducted and tested by comparing the ageing factor of the catalyst with a number of threshold values of different levels. Process for conducting and testing the activity of a NOx storage catalyst (18) arranged in an exhaust gas channel (16) of an I.C. engine (10) comprises: (a) calculating the actual storage capacity of the catalyst from the stored amount of NOx and the associated degree of charge of the catalyst using a signal receiver (21) arranged downstream of the catalyst; (b) deriving an ageing factor for the catalyst which describes the actual storage capacity of the catalyst reduced by external influences; and (c) comparing the ageing factor with a number of threshold values of different levels, where the level of the threshold value decreases with increasing distance traversed by the catalyst. On exceeding each threshold value, different operating strategies for the catalyst and/or engine can be introduced.