Method of preparing test gas mixtures containing nitrogen oxides and device for carrying out such a method

TLDR: In this paper, a method of preparing test gas mixtures containing nitrogen oxides such as NO and/or NO2 for calibrating NO/NO2 analysers is described, where ammonia (NH3) is added to a carrier gas containing oxygen, in particular air, in a certain amount to achieve a certain concentration of ammonia in the carrier gas, in that the gas mixture leaving the catalyst material serves as test gas mixture.

Abstract: The invention relates to a method of preparing test gas mixtures containing nitrogen oxides such as NO and/or NO2 for calibrating NO/NO2 analysers. The method is characterised in that ammonia (NH3) is added to a carrier gas containing oxygen, in particular air, in a certain amount to achieve a certain concentration of ammonia in the carrier gas, in that the carrier gas/ammonia mixture is passed over or through the catalyst material at a certain temperature, which catalyst material promotes a reaction of the ammonia with the oxygen, and in this process, the ammonia is burnt with oxygen at high efficiency to form nitrogen oxide (NO) and nitrogen dioxide (NO2) and possibly further combustion products, and in that the gas mixture leaving the catalyst material serves as test gas mixture. The invention also relates to a device for carrying out such a method.