Patent ID: 7485276
Filing Date: 2009-02-03
Classification: B01D,B01J,C01B,Y02A,Y02C,Y02P

Abstract:
1. A process for reducing the NO x concentration and N 2 O concentration from the tail gas from nitric acid production using an absorption column and a tail gas turbine, where the tail gas leaving the absorption column is passed, prior to entry into the tail gas turbine, through a combination of two stages, the first stage reducing the NO x content by catalytic reduction, and the second stage reducing the N 2 O content of the gas by decomposition into nitrogen and oxygen, and where the molar NO x /N 2 O ratio prior to entry of the gas into the second stage is in the range from 0.01 to 0.5, and in the second stage this gas is brought into contact with a catalyst which comprises one or more iron-loaded zeolites, the operating pressure in the second stage being from 4 to 12 bar, with the proviso that said one or more iron-loaded zeolites does not comprise FER type iron-loaded zeolite.