Operating process for removal of sulfur deposits from the pre-catalyst in an IC engine exhaust system by periodic inducing of high temperature with alternating lean and rich lambda conditions

摘要

The process for removal of sulfur deposited in the pre-catalyst of exhaust system of an IC engine which also contains a main catalyst unit, wherein the pre-catalyst is heated, at periodic intervals, to at least the desorption temperature for sulfur and: (a) during a first phase (T1), the engine is operated under rich lambda conditions (lambdaF1) until at least the main catalyst unit is essentially oxygen-free, before (b) in a consecutive second stage (T2) operating the engine in an alternating rich and lean sequence (lambdaF1), (lambdaF2) for intervals (tauF), (tauM), with the intervals time controlled so that sulfur is at least 25% converted to sulfur dioxide. An Independent claim is included for an exhaust system for a lean-burn engine implementing the above process.