Gas and liquid holdups in multi-stage bubble columns for gas-liquid-liquid-solid four-phase system

It solvents in the liquid phase are incompatible each other, a gas-liquid-solid three-phase bubble column becomes a gas-liquid-liquid-solid four-phase hubble column, Deprotection of amino acid was carried out in this column. At lower gas velocity, deactivations occur due to the deposit of product on the catalyst. At higher gas velocity, however, the catalytic activity is stable. Gas and liquid holdups in the multi-stage bubble column were measured to investigate the effects of operating conditions on hydrodynamics, Gas and liquid velocities, the height of each stage and the weight of catalyst were varied. The ratio of the organic phase holdup to the aqueous phase holdup changes drastically with the increase in gas velocity. The organic phase becomes continuous at lower gas velocity and the aqueous phase becomes continuous at higher gas velocity. Gas holdup is almost independent of each stage height and the catalyst weight.