Effect of Dispersion of the Active Phase on the Activity and Coke Formation over WO3/SiO2 Catalysts in the Metathesis of Ethylene and 2-Butene

SSCI-VIDE+ATARI+NPO:FCAInternational audienceWO3/SiO2 catalysts with various tungsten loadings were prepared by the incipient wetness impregnation method and studied in the metathesis of ethylene and trans-2-butene as feed to produce propylene. Two different calcination methods were used to modify the dispersion of the tungsten active phase. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, nitrogen physisorption, ion-exchange titration, FT-Raman, ammonia temperature programmed desorption and temperature programmed oxidation. Better dispersion is obtained from low heating rate calcination. The dispersion of tungsten showed a direct effect on coke formation and was the key factor to improve the stability of the catalysts

Effect of 2-Butene Cis/Trans Isomers in the Metathesis of Ethylene and 2-Butene Over WO3/SiO2 Catalysts

SURFACES+NPOPure 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 WO3/SiO2 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 (NH3-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

Nanometer WOx species evidenced by HRTEM/EDX in WO3/SiO2 catalysts for the metathesis reaction

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Second metals (Lanthanum, Cerium, and Yttrium) modified W/SiO2 catalysts for metathesis of ethylene and 2-butene

SSCI-VIDE+ATARI+FCAInternational audienceMetathesi

Ethylene and mixed 2-butene cis/trans isomers metathesis: Influence of lanthanum as a second metal on the WO3/SiO2 catalysts

SSCI-VIDE+ATARI+NPO:FCAInternational audienceLanthanum (0.5, 0.6, 0.75, 0.9 and 1 wt%) was added as a second metal onthe 9 wt% WO3/SiO2 catalysts by the incipient wetness impregnationmethod. The catalysts were tested in the metathesis reaction of ethyleneand 2-butene using either pure 2% trans-2-butene and the mixture of 1%cis- and 1% trans-2-butene as the reaction feed and were characterizedby X-ray diffraction (XRD), nitrogen physisorption (BET), inductivelycoupled plasma optical emission spectrometry (ICP-OES), scanningelectron microscopy, ion-exchange titration, FT-Raman, ammoniatemperature programmed desorption (NH3-TPD) and reactant temperatureprogrammed desorption (reactant-TPD). An optimum lanthanum loading at0.5 wt% could improve dispersion of tungsten active phase and adsorptionproperties of the reactants on the catalysts. The adsorption of themixed cis/trans-2-butene isomer was much improved on the La-WO3/SiO2catalysts with 0.5 wt% La

Evidence for the Presence of Nanometer WOx Species in WO3/SiO2 Catalysts for the Metathesis Reaction. [+ Affiche]

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