External mass transfer performance of micropacked bed reactors (μPBRs) with Pd/Al 2 O 3 /nickel foam catalysts is investigated by the hydrogenation of α-methylstyrene (AMS). The external mass transfer limitation region for AMS hydrogenation can be determined by means of the apparent activation energy and internal effectiveness factor. Parametric studies for external mass transfer are conducted by varying temperatures, operating pressures, liquid viscosities, gas and liquid superficial velocities, and pore diameters of foam packing. The external volumetric mass transfer coefficients [(ka) OV ] of μPBRs with the Pd/Al 2 O 3 /nickel foam range from 0.06 to 0.71 s −1 . An empirical correlation of (ka) OV is developed. Based on the gas−liquid−solid process analysis, the external mass transfer of μPBRs with the Pd/Al 2 O 3 /nickel foam is limited by liquid−solid mass transfer under the experimental conditions. Moreover, μPBRs with the Pd/Al 2 O 3 /nickel foam exhibit the best energy efficiency in comparison with that of other multiphase reactors.

Pressure drop, residence time distribution, dispersive behavior, liquid holdup, and mass transfer performance of gas–liquid flow in micropacked bed reactors (μPBRs) with different contact angles (CA) of particles are studied. The value of pressure drop for three types of beads can be obtained: copper beads (CA = 88.1°) > stainless steel beads (CA = 70.2°) > glass beads (CA = 47.1°). The liquid axial dispersion coefficient is 1.58 × 10−6 to 1.07 × 10−5 m2/s for glass beads and copper beads, which is smaller than those of trickle bed reactors. The liquid holdup of 400 μm copper beads is larger than that of 400 μm glass beads. The ratio of effective interfacial area enhancement is evaluated up to 55% for big contact angle beads compared with the hydrophilic glass beads. In addition, correlations of pressure drop, liquid holdup, and effective interfacial area in μPBRs with different wettability beads are developed and predicted values are in agreement with the experimental data.

In this work, continuous furfural hydrogenation to furfuryl alcohol in micropacked bed reactors (μPBRs) is investigated. The performances of Cu-, Ni-, Pd-, and Pt-based catalysts for furfural hydrogenation reaction are...

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