| abstract |
An internal combustion engine in an engine exhaust passage of which an NO x adsorption catalyst ( 12 ) adsorbing NO x contained in exhaust gas at the time of a low temperature and desorbing the adsorbed NO x when the temperature rises and an NO x storage catalyst ( 14 ) are arranged. When the NO x storage catalyst ( 14 ) can store NO x , the temperature of the NO x adsorption catalyst ( 12 ) is made to forcibly rise to a target temperature at which the amount of NO x which the NO x storage catalyst ( 14 ) can store is desorbed, and the NO x desorbed from the NO x adsorption catalyst ( 12 ) is stored in the NO x storage catalyst ( 14 ). |