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

The effect of a gas pretreatment atmosphere (pure N , pure H and mixed H /N ) on the metathesis reaction between ethylene and 2-butene to propylene over calcined and non-calcined WO /SiO 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 H pretreatment showed the highest catalytic performances. As revealed by various characterization results from N physisorption, XRD, XPS, TEM, SEM-EDX, UV-Vis, Raman, H -TPR, and NH -TPD techniques, the WO phase occurring from the H 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 W species were obtained on the H -treated non-calcined WO /SiO catalyst.