STEAM EFFECTS IN 3-WAY CATALYSIS

Steam can exert two main effects in three-way catalysis (i) it is a re actant which can oxidize the carbon monoxide by water-gas shift and th e hydrocarbons by steam reforming (ii) it is a major component of the exhaust gas which can affect significantly the thermal stability of th ree-way catalysts. The role of water as a co-reactant in oxidation rea ctions as well as its role in catalyst sintering are successively revi ewed. Most investigations having been carried out with PtRh catalysts, no definite conclusion can be given as far as palladium catalysts are concerned.