Differences in acid and catalytic properties of W incorporated spherical SiO 2 and 1%Al-doped SiO 2 in propene metathesis

Propene self-metathesis to ethylene and 2-butene was investigated over tungsten-based catalysts (9 wt.% W) supported on silica and 1%Al-doped SiO 2, prepared by different processes. On pure SiO 2, incorporating WO x improved tungsten dispersion and formation of active tetrahedral WO x species, compared to the impregnated ones. However, negative effect was found when tungsten was incorporated in the 1%Al-doped SiO 2 as the catalysts contained more crystalline WO x, lower tetrahedral species, and lower Lewis acid sites, compared to the W-imp 1Al 2 O 3 /SiO 2 prepared by impregnation. Incorporating both W and Al in the SiO 2 by sol-gel method may lead to suppression of bridge hydroxyl Si(OH)Al group, as a consequence more crystalline WO x was formed. Nevertheless, the abundance of Bronsted and Lewis acid was found to play important role in the propene metathesis and the secondary metathesis of 1-butene reactions than surface silanol and the presence of tetrahedral tungsten oxide species on the 1%Al-doped SiO 2 supported catalysts.