Catalytic Reduction of Nitric Oxide on Ruthenium

Abstract

The details of nitric oxide catalytic reduction by carbon monoxide and hydrogen over a supported ruthenium catalyst have been investigated. The feed stream used in these studies resembled automotive exhaust. The effect of space velocity and various reactant concentrations on the ammonia/nitrogen product distribution were studied along with the effect of these various parameters on the rate of nitric oxide removal. The pertinent chemical reactions in this system and the limitations imposed by an exhaust gas feed stream are discussed.

Electrophoretic study of RuO2/γ‐Al2O3 samples used in the water gas shift reaction

“…(111) a r a n g e of m e t a l Finally, figure 3 shows that the activity of the sample with metal content higher than 21 6 wt % is extremely larger than the activity of those samples with metal content near 0.1-0.2 wt% used in previous studies (5,6), in which it was proved that the CO conversion rate of the latter samples is more active than the classic Cu-Cr catalysts. The above representation, together with the electrophoretic migration measurements and catalytic behaviour, gives us a fairly accurate description of the Ru02/y-A1203 systems in the W.G.S.R.…”

Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces

“…It is favored not only for its high activity but also because under exhaust conditions it has been shown to be more selective to the formation of Ng over ammonia (2)(3)(4)(5)(6)(7)(8) than platinum or rhodium.…”

“…Klimisch (4) found that for the reduced case, which is the condition of the ruthenium under typical engine exhaust conditions, the reaction mechanism appears to differ from that under oxidizing conditions (7). Under reducing conditions, the formation or decomposition of ammonia was found not to be a major pathway from NO to and that if the CO concentration was reduced, the concentration of NH^ in the exhaust stream decreased in spite of the presence of hydrogen.…”

Kinetics of the Ruthenium-Catalyzed Reduction of Nitric Oxide by Hydrogen

“…Other catalysts gave selectivities as high as 90%. While Taylor and Klimisch (1973) later determined that ammonia was not an important intermediate over the reduced ruthenium catalyst, the decomposition of NH3 was in fact a major route to N2 over the "oxidized' form of the catalyst (Klimisch and Taylor, 1975). Their space velocity tests provided necessary but not sufficient evidence for NH, intermediacy.…”