Effect of pretreatment atmosphere of WO x /SiO2 catalysts on metathesis of ethylene and 2-butene to propylene

The effect of a gas pretreatment atmosphere (pure N2, pure H2 and mixed H2/N2) on the metathesis reaction between ethylene and 2-butene to propylene over calcined and non-calcined WO3/SiO2 catalysts was investigated. The non-calcined catalysts exhibited higher activity than the calcined catalysts under different gas pretreatment atmospheres. The non-calcined catalyst with the use of pure H2 pretreatment showed the highest catalytic performances. As revealed by various characterization results from N2 physisorption, XRD, XPS, TEM, SEM-EDX, UV-Vis, Raman, H2-TPR, and NH3-TPD techniques, the WO2.83 phase occurring from the H2 pretreatment of the non-calcined catalyst played an important role on the high activity of the catalyst. In addition, better tungsten dispersion, higher isolated surface tetrahedral tungsten oxide species, and W5+ species were obtained on the H2-treated non-calcined WO3/SiO2 catalyst.The effect of a gas pretreatment atmosphere (pure N2, pure H2 and mixed H2/N2) on the metathesis reaction between ethylene and 2-butene to propylene over calcined and non-calcined WO3/SiO2 catalysts was investigated. The non-calcined catalysts exhibited higher activity than the calcined catalysts under different gas pretreatment atmospheres. The non-calcined catalyst with the use of pure H2 pretreatment showed the highest catalytic performances. As revealed by various characterization results from N2 physisorption, XRD, XPS, TEM, SEM-EDX, UV-Vis, Raman, H2-TPR, and NH3-TPD techniques, the WO2.83 phase occurring from the H2 pretreatment of the non-calcined catalyst played an important role on the high activity of the catalyst. In addition, better tungsten dispersion, higher isolated surface tetrahedral tungsten oxide species, and W5+ species were obtained on the H2-treated non-calcined WO3/SiO2 catalyst.