PURPOSE: To prevent the lowering in reactivity by reducing the cracking of a catalyst at the time of charging, by packing a reaction tube with a pellet catalyst by falling the pellet catalyst from the upper part of the reaction tube while raising air through the reaction tube from the lower part thereof at a speed 0.5W2 times the min. fluidizing speed of said catalyst.

CONSTITUTION: When catalyst pellets are charged in a reaction tube 2, said catalyst pellets 1 are fallen through the reaction tube 2 from the upper part thereof to pack the same while air is raised through the reaction tube 2 from the lower part thereof at a speed 0.5W2 times the min. fluidizing speed of said pellets 1. By performing this packing, the cracking of the catalyst pellets is reduced at the time of charging and the lowering in reactivity due to cracking is reduced. Further, there is such effect that the clogging of a reactor by the fine powder on the bottom part of the reactor formed by cracking at the time of charging becomes hard to generate and the non-uniformity of reaction in the reactor is hardly generated because cracking is reduced.