Patent ID: 8065870

Claim:
A method of reducing an amount of oxide of nitrogen (NO x compound) in an exhaust gas flow of a combustion engine which is adapted for operation by a lean air/fuel mixture, said method comprising steps of: feeding the exhaust gas flow from the engine into an exhaust gas operated turbine of a turbo-aggregate; separating in the separation unit a gas component from the exhaust gas flow, said gas component being constituted by an oxide of nitrogen (NO x compound) or water present in the exhaust gas flow, in a wall structure comprising a porous material which provides a selective passage of the gas component through the wall structure before other gas components in the exhaust gas flow based on molecular size and molecular form; returning the separated gas component to an inlet of the engine via a conduit and compressing the separated gas component from the conduit in a compressor of the turbo-aggregate, said gas component including fresh air as a carrier gas for the gas component; detecting an amount of the oxide of nitrogen (NO x compound) in the exhaust gas flow for controlling the amount of the oxide of nitrogen (NO x compound) present in the exhaust gas flow, and wherein the method includes an additional step of supplying a reducing agent to an inlet of the separation unit for a catalytic reduction of the gas component in the wall structure by the reducing agent.