The influence of preparation procedures and tungsten loading on the metathesis activity of ethene and 2-butene over supported WO3 catalysts

A series of catalysts composed of WO3, γ-Al2O3 and HY were prepared to study the effects of preparation procedure and tungsten loading on their catalytic performances for the metathesis between ethene and 2-butene to propene. The catalysts are characterized by X-ray diffraction (XRD), temperature-programmed desorption of ammonia (NH3-TPD), temperature-programmed reduction of hydrogen (H2-TPR), N2 adsorption, UV–vis and UV resonance Raman techniques. The results reveal that the catalytic activity is determined by the structure of supported tungsten oxide species. Based on the correlation between the activity and structure of tungsten oxide species, the isolated tetrahedral oxide species are suggested to be the active sites precursors, which exhibit characteristic Raman band at 970 cm−1.

The correlation between the structure of supported tungsten oxide species and metathesis activities are investigated by UV Raman spectroscopy. Through the variation of preparation procedures and tungsten loadings, various tungsten species are co-present upon the Al2O3–HY support. The isolated tetrahedral tungsten oxide species are present on all active catalysts and should be the active sites precursors, which exhibit a characteristic Raman band at ∼970 cm−1. Figure optionsDownload as PowerPoint slide