Gas–liquid–solid “slurry Taylor” flow: Experimental evaluation through the catalytic hydrogenation of 3-methyl-1-pentyn-3-ol

A G–L–S “slurry Taylor” flow is investigated for the three-phase catalytic hydrogenation of 3-methyl-1-pentyn-3-ol in a capillary reactor. A system to continuously feed a homogeneous liquid–solid suspension without flow fluctuation is designed and validated allowing delivery of a stable and controlled gas–liquid–solid “slurry Taylor” flow. The catalyst particles are transported as a suspension by means of internal vortices occurring in the liquid slugs of the segmented flow. This original contact mode involving a solid catalyst in a continuous milli-reactor is evaluated by performing the fast catalytic hydrogenation of 3-methyl-1-pentyn-3-ol on a palladium catalyst supported on silica. The results obtained for this contactor show an excellent repeatability and are compared with those obtained in a laboratory stirred tank vessel under semi-batch conditions. Conditions to achieve reaction limited regime have been identified for both reactors demonstrating the good mass transfer performances of the “slurry Taylor” flow. An alternative way to monitor the reaction progress through simple image analysis of the H2 bubble shrinkage is also studied and discussed. This technique allowed a conversion profile to be established over the corresponding residence time comparable with the results obtained in the laboratory-scale batch reactor and the final GC measurements.

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► Homogeneous and stable solid catalyst suspension in a G–L reacting segmented flow.
► Good repeatability obtained in reaction.
► Comparable results in the continuous “slurry Taylor” flow vs. batch.
► Non-invasive reaction follow-up through bubble shrinkage monitoring.