Abstract: A plurality of catalyzer beds are arranged in series in a reactor jacket. Associated with each catalyzer bed is a plurality of distributor pipes for supplying a fresh catalyst and a plurality of draining pipes for draining off the used catalyst. In one embodiment, the reactor jacket is rotatable and the plurality of distributor pipes are connected to an upper edge of the catalyzer bed while the plurality of draining pipes are connected to a lower edge of the catalyzer bed so that when the reactor jacket is rotated to a position that tilts the catalyzer beds the used catalyst will drain off. In another embodiment, the lower surface of the catalyzer beds are formed of two pivotable plates which pivot downwardly and away from each other to allow for the draining of the used catalyst.