GB1307754A - Cement flashing in polymerization processes - Google Patents

Abstract

1307754 Copolymerizing olefins ESSO RESEARCH & ENG CO 5 Aug 1970 [26 Aug 1969] 37806/70 Heading C3P Unreacted higher α-olefin and diluent are recovered from liquid reactor effluent from a reaction operation and containing catalyst, unreacted higher α-olefin and a cement of ethylene/higher α-olefin copolymer in a liquid diluent wherein the higher α-olefin has a boiling point at least 50‹ C below the boiling point of the diluent, by a method which comprises (a) withdrawing liquid effluent from a reactor, (b) quenching said effluent with a non- volatile catalyst inactivating agent, (c) heating and compressing the quenched effluent, flashing the quenched effluent to separate unreacted ethylene and a major portion of unreacted higher α-olefin as overhead and a copolymer cement in diluent containing a minor portion of unreacted higher α-olefin as bottoms, (e) heating and compressing the first flash bottoms, (f) flashing said bottoms to a pressure substantially equal to the first flash pressure to separate diluent and remaining unreacted ethylene and higher α-olefin as flash overhead and polymer cement substantially free from unreacted higher α-olefin as flash bottoms, and (g) recovering said copolymer cement. The flash overheads may be combined, mixed with diluent, condensed and recycled to the reaction. The α-olefin may be a linear or branched C 3-10 olefin, preferably propylene, and a third monomer, e.g. a non-conjugated diene, may also be present. The catalyst may comprise a titanium or vanadium halide and an organo aluminium compound, and the diluent may be a hydrocarbon or halogenated hydrocarbon. Quenching may be effected with a non-volatile polyol, organic acid, aniline or nitrobenzene. The method may be effected continuously. Apparatus suitable for carrying out the method is described and illustrated and an example describes the copolymerization of ethylene, propylene and 5-ethylidene-2-norbornene in hexane in the presence of vanadium tetrachloride and diethyl aluminium chloride, the reaction being quenched with 4,4-thio bis (6-t.butyl-m-cresol).