Exhaust gas catalyst unit used in direct injection diesel engines of vehicles comprises tempering coiled tubing which surrounds outer sleeve of nitrogen oxide reduction catalyst body

摘要

An exhaust gas catalyst unit comprises a nitrogen oxide reduction catalyst body (1) through which the gas flows and a tempering coiled tubing (4) which surrounds an outer sleeve (3) of the catalyst body. An Independent claim is also included for a process for operating an exhaust gas purification device comprising an exhaust gas catalyst unit in which a cooling fluid flow is regulated by the coiled tubing so that the temperature of the nitrogen oxide reduction catalyst body in an edge zone bordering the outer sleeve does not exceed the upper boundary temperature of a nitrogen oxide reduction effective temperature region. Preferred Features: The outer sleeve (3) is free from heat insulation.