A unique reactor configuration especially suitable for interphase mass
transfer and mixing of multiple phases, i.e. gas(es), liquid(s), and
solid(s) where reaction is catalyzed by a solid catalyst comprises a
draught tube reactor wherein the solid catalyst particles are maintained
in an annular space between the draught tube of the reactor and an
annulus-defining wall by means of filter elements positioned downstream
and optionally also upstream from the catalyst bed.