GB906464A - A cyclic process for the production of alpha olefins - Google Patents

Abstract

Alpha olefins are produced in a cyclic process which comprises (1) thermally decomposing a complex of the formula K[AlR2X2], in which R is an alkyl radical or substituted alkyl radical of at least two carbon atoms and having no branching or unsaturation on the carbon bonded to aluminium and X is chlorine or bromine, to produce a distillate comprising R2AlX and AlR3 and a residue of KX and K[AlR2X2] and possibly K[AlRX3]; (2) reacting the distillate from (1) with ethylene at 90-150 DEG C. and elevated pressure to build up the alkyl groups of the aluminium compounds; (3) displacing the higher alkyl groups with ethylene or other alpha olefin in the presence of nickel, cobalt or platinum; (4) mixing the product with the residue from (1) to reform the complex; (5) separating the olefins containing nickel, cobalt or platinum from the complex K[AlR2X2] which is recycled to step (1). Steps (3) and (4) may be reversed or part of the residue from step (1) may be added to the product of (2) and the remainder added after the displacement (3). If desired the process may be begun at step (2) with a mixture of R2AlX and AlR3 and after step (3) KX with AlR3 if necessary is added to form the complex which is then decomposed in step (1). Separation of the complex from the olefins in step (5) may be by running off the lower liquid complex phase or by allowing it to cool to form a solid mass and the olefins poured off. The complex may be extracted with an aliphatic hydrocarbon to remove traces of olefins. The olefins are distilled to separate them from the nickel cobalt or platinum. Suitable displacing olefins are ethylene, propylene and butene-1; the first and last yield eventually olefins with an even number of carbon atoms, propylene yields olefins with an odd number. If desired different displacing olefins may be used from cycle to cycle. Specifications 770,707, 777,152 and 879,269 are referred to.