Concurrent production from ethylene of alpha olefins and alkyl aluminium compounds

摘要

A process for the concurrent production from ethylene of alpha olefins of desired molecular weight range and alkyl aluminium compounds comprises the combination of (a) an ethylene polymerization stage, wherein ethylene is polymerized to higher alpha olefins having a molecular weight range broader than the desired range in the presence of a trialkyl aluminium catalyst, separating an alpha olefin fraction in the desired molecular weight range from the polymerization product, and also separating an alpha olefin fraction having a molecular weight lower than the desired range, and (b) a chain growth stage, wherein a displacement reaction is effected between a trialkyl aluminium feed and at least part of said olefin fraction of molecular weight lower than the desired range, and reacting the resulting modified trialkyl aluminium with ethylene to produce by stoichiomeitrc chain growth the alkyl aluminium compounds. As shown, ethylene is fed to a catalytic polymerization unit 5 and a chain growth stoichiometric section 21. Tri-alkyl aluminium, e.g. tri-isobutyl aluminium, is also fed to unit 5 and to a displacement reaction section 15. The tri-alkyl aluminium fed to unit 5 and section 15 need not have the same alkyl substituents. The effluent from unit 5 is generally a mixture of C4-C30 a olefins and trialkyl aluminiums having alkyl substituents corresponding in chain length to the olefins prepared. Separation of a -olefin fractions is effected in stage 10, wherein provision is made for recycling of certain alpha-olefins, e.g. C4-C6 olefins, to the catalytic polymerization stage, for the discharge of product streams, e.g. C12-C16 a -olefins, and for the transfer of a selected cut to the displacement reaction stage 15, e.g. C8-C10 a -olefins. In stage 15, tri-alkyl aluminiums corresponding to the a -olefins transferred from separator 10 are formed and the effluent from stage 15 is passed to a separator 18 wherein a -olefins are separated from tri-alkyl aluminiums, which are then passed to the chain growth stage 21, where reaction is effected with ethylene to give the desired tri-alkyl aluminiums e.g. those having alkyl groups containing 12 to 16 carbon atoms. Catalytic polymerization may be effected at 700-4000 p.s.i.g., preferably 2000-4000 p.s.i.g., at 170 DEG -225 DEG C. The displacement reaction may be carried out at 1000-1500 p.s.i.g. at 150 DEG -200 DEG C. Primary alcohols are prepared from the trialkyl aluminiums obtained from the chain growth stage, for example, by gaseous oxidation of the latter to aluminium trialkoxides, hydrolysis of the latter with aqueous acid, e.g. HCl, H2SO4, separation of the alcohol phase from the aqueous phase, and fractionation of the alcohol phase into desired cuts. A typical weight distribution of alcohols obtained is C6 1%, C8 6%, C10 18%, C12 25%, C14 22%, C16 14%, C18 and higher 14%.ALSO: A process for the concurrent production from ethylene of a -olefins of desired molecular weight range and alkyl aluminium compounds comprises the combination of (a) an ethylene polymerisation stage, wherein ethylene is polymerized to high alpha-olefins having a molecular weight range broader than the desired range in the presence of a trialkyl aluminium catalyst, separating an a -olefin fraction in the desired molecular weight range from the polymerization product, and also separating an a -olefin fraction having a molecular weight lower than the desired range, and (b) a chain growth section, wherein a displacement reaction is effected between a trialkyl aluminium feed and at least part of said olefin fraction of molecular weight lower than the desired range, and reacting the resulting modified trialkyl aluminium with ethylene to produce by stoichiometric chain growth the alkyl aluminium compounds. As shown, ethylene is fed to a catalytic polymerization unit 5 and a chain growth stoichiometric section 21. Tri-alkyl aluminium e.g. (tri-isobutylaluminium) is fed to unit 5 and to a displacement reaction section 15. The trialkyl aluminium fed to unit 5 and section 15 need not have the same alkyl substituents. The polymers produced in unit 5 are predominantly C4-C30 a -olefins, and these are separated into fractions in separator unit 10. Thus, a C4-C6 fraction may be recycled to unit 5, a C8-C10 fraction transferred to displacement section 15, a C12-C16 fraction collected as a product stream. Catalytic polymerization may be effected at operating pressures of 700-4000 p.s.i.g., preferably 2000 -4000 p.s.i.g., at 170 DEG -225 DEG C. The displacement reaction may be carried out at 1000-1500 p.s.i.g. at 150-200 DEG C.