Fries rearrangement of phenyl acetate catalysed by platinum-doped heteropoly salt: Catalyst regeneration and reuse

The acidic cesium hetetropoly salt Cs2.5H0.5PW12O40 (CsPW) is an active solid acid catalyst for the liquid-phase Fries rearrangement of phenyl acetate, which, similar to other solid acid catalysts, suffers from deactivation due to coke deposition. Coke burning cannot effectively regenerate CsPW because of its relatively low thermal stability. Doping CsPW with Pt metal (0.3 wt%) allows full regeneration of catalyst activity and selectivity by the aerobic oxidation of coke at 350 °C and ambient pressure, which occurs without any structural damage to the catalyst. Pt doping practically does not affect the activity and selectivity of CsPW. As a coke-burning catalyst, Pt is much more efficient than Pd; the latter requires almost ten times higher a metal loading. The Pt/CsPW catalyst is characterised by XRD, TGA/TPO, FTIR and H2 chemisorption.