Friedel-Crafts acylation of toluene with acetic anhydride catalysed by H_3PW_(12) O_(40) /SiO_2

The Friedel-Crafts acylation of toluene with acetic anhydride to methylacetophone in liquid phase with silica-supported 12-phosphotungstic acid (PW/SiO_2) as catalyst were investigated. PW/SiO_2 catalysts prepared with different calcination temperatures and PW loadings were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) and NH_3 temperature-programmed desorption (NH_3-TPD). The effects of catalyst composition, pretreatment and reaction conditions on the reaction behaviour were examined. The results showed that the PW loadings and calcination temperatures have significant influences on the acidity, PW dispersion and catalytic activity of PW/SiO_2; the catalyst calcined at 300℃ with a PW loading of 40% exhibits the best catalytic performance. For the acylation of toluene with acetic anhydride over PW(40%)/SiO_2 at 130℃, the highest methylacetophone yield was achieved with the weight ratio of catalyst to acetic anhydride being 2.2.