Surface Active Sites of Modified Zeolites and Zirconia in the Conversion of Nitrogen(I, II) Oxides

Abstract

Samples of zirconia doped with transition metal (Cr, Co, Ce) oxides, and also rhodium-promoted and Fe-containing zeolites of different structural types, were studied by NH 3 -TPD and IR spectroscopy. The various samples were analyzed with respect to their catalytic performances in deNO x reactions, in particular the selective catalytic reduction of NO (N 2 O) using hydrocarbons as reducing agents (HC SCR). Bifunctional zeolite-and ZrO 2 -based catalysts exhibited high activity in the SCR of nitrogen(I, II) oxides to dinitrogen due to the combination of the surface redox and acidic properties exhibited by these materials.