Abstract: A rotation driving system drives unitedly and rotatably sprinkle rotors, which the disk sprinkle rotors having plural partitive members extending in predetermined distances in a radial direction to the rotating axis are arranged in multistage state with a predetermined distance in a longitudinal direction. In the aforementioned state, by supplying the catalyst to the center of the sprinkle rotor, the catalyst is fed into a reaction tank while releasing in a radial direction of the sprinkle rotor. When the catalyst is fed, a rotation frequency of the sprinkle rotor is defined to be a speed constituent in a radial direction of over zero when the catalyst settles down and to be periodically changed between a maximum rotation frequency and a minimum rotation frequency.