Ruthenium(III) ion-exchanged zeolite Y as highly active and reusable catalyst in decomposition of nitrous oxide to sole nitrogen and oxygen

Abstract

Ruthenium(III) ion-exchanged zeolite Y, prepared by ion exchange of Ru+3 ions with the extra framework Na+ cations in zeolite Y with a Si/Al ratio of 2.5, is employed to catalyze the decomposition of nitrous oxide to nitrogen and oxygen. Catalytic activity of ruthenium(III) ion-exchanged zeolite Y is studied in the decomposition of nitrous oxide to nitrogen and oxygen depending on the ruthenium loading of zeolite and flow rate of nitrous oxide helium mixture in a continuous flow vertical reactor. The results collected reveal that ruthenium(III) ion-exchange zeolite with a ruthenium loading of 3.98wt.% is highly active, long-lived, and reusable catalyst providing 100% conversion of nitrous oxide to sole nitrogen and oxygen at 350°C without any side reaction. This catalyst can be bottled under ambient conditions and repeatedly used in successive runs of nitrous oxide decomposition for up to 5months without significant loss in activity. Intrazeolite ruthenium(0) nanoclusters are slightly less active than the ruthenium(III) ion-exchanged zeolite Y in decomposition of nitrous oxide, which might be attributed to the migration of ruthenium(0) to the external surface before oxidation at high temperature. The other two metals of Group 8, iron(III) and osmium(III) ion-exchanged zeolite Y do not show activity as high as that of ruthenium(III) ion-exchanged zeolite Y in the same reaction.