PURPOSE: To stably and continuously obtain an olefinic polymer for a long period using a compact polymerizer by carrying out the polymerization of an olefin in the vapor phase while circulating a specific low-boiling solvent to a specified position in the vapor-phase polymerizer.
CONSTITUTION: This method for polymerizing an olefin is to perform a regular polymerizing step for initially (co) polymerizing the olefin with a solid catalyst component in the vapor phase in the presence of a low-boiling point unpolymerizable hydrocarbon (hereinafter referred to as a hydrocarbon) in a reactional system holding the fluid state, then the first circulating step for circulating a part of the hydrocarbon discharged from the upper part of the vapor-phase polymerizer from the lower part of the vapor- phase polymerizer and feeding the part of the hydrocarbon to the regular polymerizing step and the second circulating step for liquefying a part of the hydrocarbon discharged from the upper part of the vapor-phase polymerizer and circulating the part of the hydrocarbon to the reactional system in the vapor-phase polymerizer. Furthermore, when the olefin fed in the first circulating step and/or the second circulating step is polymerized in the vapor phase, the liquefied hydrocarbon is circulated to the vicinity of the powder surface of the fluidized bed so as to be kept in a liquid state and brought into contact with powdery particles scattering upward from the powder surface of the fluidized bed.
DOI KENJI
UETAKE TAKAO
MORITA YOSHINORI
