Kinetics of phenol hydrogenation over Pd-containing hypercrosslinked polystyrene

Hypercrosslinked polystyrene (HPS) has been used as a support for preparation of the palladium-based catalyst, Pd/HPS, for gas phase hydrogenation of phenol to cyclohexanone. At the phenol conversion 99%, the catalyst provides selectivity for ketone not lower than 95 mol%. The Pd/HPS catalyst showed high stability, retaining its catalytic performance at least for 20 days. Kinetics was used to compare Pd/HPS with the commercial Pd/Al2O3 catalyst. The catalytic efficiency was assessed using the derived dimensionless kinetic equation without a ‘time’ parameter. Three major reaction routes with their rate parameters and activation energies were revealed. From kinetic parameters, the maximum possible yield of cyclohexanone in the temperature range of 120–180 °C was determined. The important feature of the Pd/HPS catalyst is that selectivity is independent of the temperature at a certain phenol conversion. At elevated temperatures (160–180 °C), the selectivity is at least 2–3% higher as compared to the commercial catalyst Pd/Al2O3, which makes Pd/HPS largely promising for industrial applications.

► Hypercrosslinked polystyrene as a support for Pd/HPS catalyst.
► Phenol selectivity for cyclohexanone not lower than 95 mol% at the conversion 99%.
► Selectivity is independent of the temperature.
► Kinetics is used to compare Pd/HPS with the commercial Pd/Al2O3 catalyst.