Transfer Dehydrogenation of 1-Phenylethanol Over Pd/C Under Mild Conditions: Effect of Reaction Conditions and Optimization of Catalytic Performance

Abstract

The catalytic activity of 5 wt% Pd/C has been evaluated using the liquid phase transfer dehydrogenation of 1-phenylethanol as a model reaction. The reaction parameters such as catalyst loading and stirring rate have been optimized to determine the required conditions to carry out the reaction under kinetic regime control. By performing the reaction under different temperatures, the value of apparent activation energy has been determined as being 61 kJ/mol. Furthermore, the influence of thermal treatment of 5 wt% Pd/C catalyst on its catalytic performance for the liquid phase transfer dehydrogenation of 1-phenylethanol has been investigated in a temperature range of 110–200 °C. The results reveal that the catalyst activity is strongly dependent on the ratio between Pd/PdO species. The fresh and used catalysts were characterized using a range of characterization techniques (XRPD, XPS, TEM, SEM-EDX, and BET) in order to investigate structure–activity relationships. The 5 wt% Pd/C exhibit high conversion (90%) and selectivity (91%) toward acetophenone under mild conditions. Moreover, the reusability tests have been carried out, and the results show that the catalyst preserves 80% of its initial catalytic activity after five cycles indicating the high stability of the 5 wt% Pd/C catalyst in the liquid phase transfer dehydrogenation of 1-phenylethanol. The influence of reaction conditions on the catalytic activity is also discussed.