A method for the selective catalyst reduction of nitrous oxide (N.sub.2 O)
in the presence of a solid catalyst, with the addition of a saturated
hydrocarbon as reducing agent. The catalyst used is a promoted,
iron-containing zeolite. As a result, it is possible to increase the
conversion of (N.sub.2 O) compared to unpromoted iron-containing zeolite
catalysts. The promoted catalyst is active at temperatures below
350.degree. C. Furthermore, it has been found that the iron-containing
zeolite catalysts which are promoted with precious metal also give low
emissions of CO and residual hydrocarbons. The catalyst is also very
active under high process pressures and in the presence of sulphur.
