11th International Congress CoPt Clusters in Na Mordenites as catalysts for SCR of NOx

L. GUTIERREZ; A. RIBOTTA; A. BOIX; J. PETUNCHI

Studies in Surface Science and Catalysis

Elsevier

Lugar: Amsterdam; Año: 1996; p. 631 - 640

A new material based on Pt and Co exchanged in NaMordenite for the selective catalytic reduction (SCR) of nitric oxide with methane in the presence of excess oxygen is studied. The incorporation of 0.5% weight of Pt and 2% weight of Co to the zeolitic matrix after calcination and reduction on H2 flow for 1h yields a solid converting 100% of NO to N2 and, simultaneously, 100% of CH4 to CO2 with a CH4/ NO ratio = 3 and 2% of oxygen in the feed at 450°C. When the oxygen concentration in the feed varies, the NO conversion goes through a maximum for 2% at 450°C. The incorporation of Pt also promotes Co reducibility; 1% is reduced to Co° in the monometallic sample and 13% in the bimetallic sample. XPS results reveal that in the calcined samples Co2+ is at exchange position and, after being reduced, there appear thinly dispersed Co° particles and exchanged Co2+ ions. A greater reducibility and a shift of the maxima in the temperature-programmed reduction profiles suggest a Pt-Co interaction. In order to get an efficient catalyst for nitric oxide abatement it is necessary that the highly dispersed Co° and Pt° particles and the Co2+ and H+ ions at exchange positions be in intimate contact inside the mordenite channels.