Friedel–Crafts acylation of anisole over Cr-doped Hβ zeolite

Cr-doped Hβ zeolite is found to have better catalytic performance than Hβ zeolite in the Friedel–Crafts acylation of anisole, with acetic anhydride conversion of over 99% and nearly 100% selectivity to furnish para-methoxyacetophenone under the optimized reaction conditions. This is attributed to the increase of weak and moderately strong acid sites, caused by the Cr addition. The formation of carbonaceous materials and their coating of the acid sites are believed to be the reasons for the deactivation of the reused Cr-doped Hβ zeolite, as indicated by the Brunauer−Emmett−Teller (BET) method, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and NH3 temperature-programmed desorption (NH3-TPD) measurement results. The catalyst activity can be recovered by a subsequent calcination.