Effect of internal filtration on slurry reactor performance

In slurry bubble column reactors, generally small particles (<200 μm) are applied. These particles often introduce a strenuous liquid−solid separation in processes involving liquid-phase products. This operation can be facilitated by performing filtration inside the reactor and thereby utilizing the turbulence induced by rising gas bubbles to keep the filters clean. In previous work it was shown under what conditions in a 3-phase filtration system a cake of solids forms. In the present work the effect of filter cake formation on slurry reactor performance is studied in the regime where the intrinsic chemical kinetics partially determine the conversion rate of the species involved. For this purpose the hydrogenation of α-methylstyrene on Pd/Al2O3 powdered catalyst has been performed in a small-scale reactor. Experimentally observed drops in conversion rate on an increase of permeate flux can mainly be attributed to reduced bulk reactivity caused by cake formation. Chemical reaction in the cake itself increased the conversion rate significantly in the case where a large fraction of the catalyst moved into the cake at high permeate fluxes. Our calculations revealed that hot-spot formation in the cake does not occur for a large number of systems of practical relevance including the present one.