Axial dispersion, pressure drop and mass transfer comparison of small-scale structured reaction devices for hydrogenations

•Performance comparison of two different sized designed porous small-scale reactors.•Axial dispersion, pressure drop and mass transfer studies.•Selective 2-methyl-3-butyn-2-ol hydrogenation was used as test reaction system.•Gas–liquid mass transfer of hydrogen was the process limiting step.•Differences were found, the smaller structure showed superior mass transfer.

“Designed Porous Structured Reactor” (DPSR) is porous stream-wise periodic structure that can serve both as static mixers and catalyst carriers. Two DPSRs with different inner diameters (A: 14 mm, B: 7 mm) were compared.Residence time distributions were determined in an aqueous system at different Reynolds numbers using wire-mesh electrodes. Similar dispersion was observed in both structures, which was attributed to fully developed flow in DPSR A and B. Axial dispersion coefficients increased monotone with pore Péclet numbers and were in good agreement with literature.DPSR A showed higher pressure drops due to lower porosity values than DPSR B. Pressure drops followed the Forchheimer equation using an Ergun model. The coating reduced the surface roughness and the porosity of the DPSRs’ metal fabric.Chemical mass transfer was evaluated for the hydrogenation of 2-methyl-3-butyn-2-ol (MBY) at various gas/liquid combinations. While gas–liquid mass transfer was determined as limiting process step, liquid–solid mass transfer was ruled out. Superior gas–liquid mass transfer coefficients were determined for DPSR B. Differences in mass transfer rates DPSR A and B were attributed to the ratios of inner diameter to the pore size and the porosities. A Stanton correlation was suggested to estimate gas–liquid mass transfer coefficients.