Effect of 2-butene cis/trans isomers in the metathesis of ethylene and 2-butene over W[O.sub.3]/Si[O.sub.2] catalysts

Pure 2 % trans-2-butene and the mixture of 1% cis- and 1 % trans-2-butene were used as feed to react with ethylene in metathesis reaction in order to produce propylene to study the effect of feed on W[O.sub.3]/Si[O.sub.2] catalysts with various tungsten oxide loadings (5, 7, 9, and 11 wt%), which were prepared by incipient wetness impregnation. These catalysts were characterized by X-ray diffraction, nitrogen adsorption (BET), scanning electron microscopy, energy dispersive X-ray spectroscopy, ion-exchange titration, FT-Raman, ammonia temperature programmed desorption (N[H.sub.3]-TPD) and reactant-TPD. At high tungsten oxide loading, when the mixture of cis- and trans-2-butene was used as the reaction feed the conversion of 2-butene was lower than when pure trans-2-butene was used. However, the effect of cis-2-butene isomer on the conversion of 2-butene was less pronounced at low tungsten oxide loading. The dispersion of tungsten was a key factor to improve the activity of the tungsten catalysts when the mixture of cis- and trans-2-butene was used as a feed for metathesis reaction.