METHOD FOR REMOVING NITROGEN OXIDE AND CARBON BLACK PARTICULATES FROM LEAN EXHAUST GAS OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To avoid hazard of elevated emission of nitrogen dioxide during the combustion of carbon black for regeneration of a particulate filter in which carbon black particulates are precipitated, in a method for removing nitrogen oxide and carbon black particulates from lean exhaust gas containing also sulfur oxide.

SOLUTION: The exhaust gas stream is passed over a nitrogen oxide storage catalyst 3 and a particulate filter 4, where the storage catalyst is denitrated by periodically enriching the exhaust gas in a first operating cycle. Regeneration of the particulate filter 4 and desulfurization of the nitrogen oxide storage catalyst 3 are carried out in a second operating cycle by raising the temperature of the lean exhaust gas to a value at which the combustion of carbon black burned-out residues is initiated on the particulate filter 4 and then the storage catalyst 3 can be desulfurized by enriching the exhaust gas.

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