METHATHESIS OF ETHYLENE BUTENE MIXTURES TO PROPYLENE WITH RHENIUM ON ALUMINA CATALYSTS

The metathesis reaction of ethylene-butene mixtures and the reverse metathesis of propylene have been studied in liquid phase under pressure at near-ambient temperature and in integral-type reactors. The rhenium on alumina catalyst used has been optimized to obtain the highest activity without the formation of oligomeric byproducts, which are shown to result from a cationic reaction. Deactivation of the catalyst is seen to have various origins. An intrinsic deactivation seems always operative, but a stronger deactivation occurs when impurities are present in the reacting olefins. Some of these impurities have a reversible effect, while others behave as permanent poisons. It is proposed that the stability of the catalyst with time is governed, at least in part, by the Lewis acidity of the active sites.