Patent ID: 8141352

Claim:
A method of purifying exhaust with an exhaust purification device, the device comprising: a NO x selective reducing catalyst; a NO x storage catalyst the NO x storage catalyst upstream from the NO x selective reducing catalyst and configured to store NO x contained in an exhaust gas comprising NO x ; and a fuel feed valve upstream of the NO x storage catalyst, the fuel feed valve being configured to feed a mist fuel from the fuel feed valve towards the NO x storage catalyst, the method comprising: feeding a mist fuel from the fuel feed valve downstream to the NO x storage catalyst and the NO x selective reducing catalyst; when the air-fuel ratio of the exhaust gas is stoichiometric or rich, releasing absorbed NO x from the NO x storage catalyst; reacting the released NO x with the mist fuel to produce an intermediate product comprising bonded molecules of NH 2 and a hydrocarbon molecule, an amount of hydrocarbon of the hydrocarbon molecule on the bonded molecules being larger than an amount of hydrocarbon used when reacting with one NO x molecule; and adsorbing the intermediate product at the NO x selective reducing catalyst.