Two-stage process and apparatus for purifying combustion gases

摘要

Process for purifying combustion gases, for example of motor vehicles, domestic heating systems or waste incineration plants, from their environmentally harmful constituents, in particular nitrogen oxides and unburnt hydrocarbons, using metal oxides individually or in a mixture with other oxide materials, in which, prior to the catalytic reaction, carbon monoxide is fed to the gases in a stoichiometric excess - based on the amount of pollutant contained in the gas - and the subsequent catalytic reaction is carried out in a two-stage procedure, the reaction proceeding in the first stage under hermetic exclusion of external oxygen and, prior to entry into the second stage, an excess - based on the content of unreacted carbon monoxide - of external oxygen being supplied to the gas. The catalyst used is iron(III) oxide or chromium(III) oxide alone or in a mixture with oxides or salts of metals, copper, titanium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel or of the rare earths. The apparatus for purifying the rapidly-flowing exhaust gases, for instance from motor vehicles, is composed of two chambers, which are arranged, spaced, one after the other in the exhaust gas pipe (exhaust pipe), to receive a support in each case containing the catalyst material or having a coating of catalyst material, between which a [lacuna] opening out into the exhaust gas pipe, which injection of ... Original abstract incomplete.