Process and device for reducing nitrogen oxides.

摘要

To reduce nitrogen oxides present in oxygen-containing exhaust gases, preferably in combustion gases from internal combustion engines, the nitrogen oxides are reacted in the presence of hydrocarbons on zeolites, into which elements of group 4 of the periodic table have been introduced by exchange. To avoid impairment of the nitrogen oxide reduction by water present in the combustion exhaust gases as far as possible, the zeolites used should be those having hydrophobic properties. Advantageously, these zeolites should have a relatively high silicon/aluminium ratio and preferably consist of zeolite of the ZSM type.