Synergistic effect of additional TiO2 support on metathesis activity of ethylene and 2-butene over supported tungsten-based catalysts for propylene production

Tungsten-based catalysts of different preparations mixed with TiO2 support were investigated in the metathesis of ethylene and trans-2-butene to propylene. The catalytic activity of silica-supported tungsten oxide catalyst (WO3/SiO2) mixed with TiO2 additional support had higher efficiency than that of mixed SiO2-TiO2 supported tungsten oxide (WO3/SiO2-TiO2). The clean area of the TiO2 additional support, which provides more space for tungsten migration, is an important key to explain the improved catalytic activity, due to the higher fraction of the isolated surface tetrahedral tungsten oxide species and better dispersion of the tungsten oxide species observed by FT Raman spectroscopy. In addition to the synergistic effect of the additional TiO2 support on the metathesis activity, the similar synergy was also observed for the one–third diluted catalysts with additional SiO2. It has been found that the synergistic effect exerted by the presence of additional SiO2 support predominates over the one-third dilution effect of catalyst concentration. Thus, adding an additional support is another simple way to improve the catalytic activity of the catalysts and makes great benefit for being used in real chemical industry.