Hydrogenation of α-Methylstyrene in a Piston-Oscillating Monolith Reactor

Abstract

The hydrogenation of α-methylstyrene (AMS) to cumene was investigated in a novel piston-oscillating monolith reactor (POMR). Low-frequency (0−17.5 Hz) and -amplitude (2.5 mm) mechanical oscillations were applied to the three-phase system at 46 °C and 0.44 MPa of H2. For comparison purposes, the reaction was also carried out in a stirred tank at identical temperatures and pressures and at similar power input per volume. Results show activity improvements of up to 84% for 17.5 Hz, 2.5 mm piston oscillations over low-frequency gas flow pulsing conditions, and significantly greater improvements when compared to trickle beds or conventional monolith reactors. The POMR also gives as good or better selectivity toward cumene than a stirred tank at identical conditions. While the effects of catalyst pretreatment and its impact on the Pd crystallite size also have an important role in determining the catalyst activity and long-term stability in AMS hydrogenation, these results suggest that the impact of low-frequency and -amplitude oscillations, applied to structured reactors, is considerable.