Selective catalytic reduction of nitrous oxide with hydrocarbons using a SO2 resistant Fe/zeolite catalyst

Removal of nitrous oxide (N2O) from exhausts of chemical plants and certain combustion facilities is an effective way for substantial reduction of greenhouse gas emissions from anthropogenic sources. ECN has developed a catalyst for catalytic removal of N2O from various exhaust gases using hydrocarbons (propane or methane) as reducing agent. The catalyst is an ion-exchanged zeolite, specially modified to improve its resistance against sulphur. In bench scale tests, the catalyst has proven to perform at relatively low temperatures. In a synthetic flue gas containing oxygen and water, 90% conversion of N2O to N2 was reached at 350 deg C. Activity decreases slightly when NO and SO2 are present. The catalyst was found to be resistant against all regular constituents of flue gases: O2, H2O, CO2, CO, NOx and most importantly SO2. In stability tests, no apparent loss of activity was recorded in 2000 hours time-on-stream. The catalyst was originally developed for selective catalytic reduction (SCR) of N2O, but recently it has also demonstrated strong activity in SCR of NOx. The capacity to remove both NOx and N2O from the same gas mixture is an interesting development, since nearly all sources of N2O also emit NOx. Investigations are still going on, but the first results indicate that ECN's SCR catalyst has a great potential for integrated SCR of NOx and N2O with hydrocarbons from a variety of off-gases