The hydrogenation of R-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 H 2 . 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.

The partial hydrogenation of soybean oil was carried out in a novel piston oscillating monolith reactor (POMR). POMR performance was studied under the application of low frequency (0-17.5 Hz) and amplitude (2.5 mm) vibrations at 110°C and 0.41 MPa H 2 using a Pd/Al 2 O 3 monolith catalyst. Results show observed rate improvements of up to 220% for 17.5 Hz, 2.5 mm piston oscillations over low frequency pulsing conditions. For comparison purposes, the reaction was also carried out in a stirred tank reactor using the monolith catalyst. The POMR showed better activity at an equivalent power per unit volume when compared to a stirred tank. With the monolith catalyst, both external and internal mass transfer limitations exist. Using standard diffusionreaction calculations and measurements over a range of particle sizes it was shown that the vibrations improve external mass transfer rates as well as internal transport within the washcoat. The POMR showed equal or better serial pathway selectivity than a stirred tank, except at the highest frequency, but gave higher trans fatty acid formation.

in Wiley InterScience (www.interscience.wiley.com).The hydrogenation of poly(styrene) over a Pd/Al 2 O 3 catalyst was studied in reactors where pulsed flows are present due to both extrusion and forced pulsing. The reaction was investigated over a range of flow rates, polymer concentrations, and pulsing conditions. Observed activities were highly related to gas-to-liquid mass transfer rates predicted by a correlation for slug flow in catalyst monoliths. A reactor fed by a liquid-starved extruder is an attractive choice for hydrogenation at low polymer concentrations, where intrinsic reaction rates are approached. Higher polymer concentrations (10 wt %) lead to higher mass transfer resistances and a decrease in observed activity. But in this case forced pulsing has a greater effect on productivity; an optimum pulsing frequency was observed. Selectivity was higher and power input lower than in a stirred tank at comparable conditions. The optimal frequency is higher than those found in previous work on hydrogenations.

No abstract