| abstract |
An exhaust gas purification device for an internal combustion engine is equipped with a first NO x selective reduction catalyst, which is provided inside the engine exhaust path and selectively reduces NO x by supplying a reducing agent, a second NO x selective reduction catalyst, which is provided in the engine exhaust path on the downstream side of the first NO x selective reduction catalyst and selectively reduces NO x by supplying a reducing agent, and a reducing agent supply device that supplies a reducing agent to the first NO x selective catalyst. The amount of reducing agent adsorbed onto the second NO x selective reducing catalyst is estimated, and the amount of reducing agent supplied from the reducing agent supply device is adjusted so that the estimated amount of adsorbed reducing agent does not exceed an allowed value. |