Patent ID: 8615985

Claim:
A method for providing a reducing-agent-containing gas flow in the exhaust system of an internal combustion engine, the method comprising the following steps: A) providing at least one reducing agent precursor as a liquid, a solid or a urea water solution; B) evaporating the at least one reducing agent precursor in a first stage at a first temperature of 180Â° C. or lower in a first zone of a duct to form a gas flow; C) at least partially heating the gas flow in a second stage following the first stage to a second temperature of 250-550Â° C. in a second zone of the duct; Câ€²) introducing the at least one reducing agent precursor alone into the first zone and conducting the at least one reducing agent precursor through the first zone and the second zone without mixing with any other substance; D) at least partially converting the reducing agent precursor in the gas flow into a reducing agent downstream of the first zone, in or after the second stage and in or downstream of the second zone to form the reducing-agent-containing gas flow; and E) adding the reducing-agent-containing gas flow to the exhaust gas of the internal combustion engine.