GB770265A - Improvements in or relating to polymerization system - Google Patents

Abstract

<PICT:0770265/IV(a)/1> Catalyst efficiency is controlled in a continuous process for the polymerization of isobutylene alone or with isoprene, butadiene, piperylene, a -methylpentadiene, a -methyl styrene, indene or vinyl napththalene to incomplete conversion, in which the reactants are mixed with a volatile diluent, e.g. methyl chloride, cooled to 10 to - 160 DEG F. and contacted with a Friedel-Crafts catalyst dissolved in the diluent, after which the diluent and unreacted materials are flashed off, compressed, dried and passed to a series of distillation towers from the first of which a high purity fraction of the diluent is taken overhead, condensed and used as a solvent for fresh catalyst, and the bottoms fraction is passed to a second distillation tower from which the remainder and main portion of the diluent is taken overhead for recycling to the polymerization zone. The improvement is obtained by automatically diverting the excess flow of the compressed, flashed materials above a predetermined amount away from the first tower and passing it to the midpoint of the second tower and conversely in the case of deficiency, automatically drawing the required amount from the overhead from the second tower, whereby a substantially constant flow of material is maintained to the first tower. In an example recycle tower feed from the copolymerization of isobutylene and isoprene in a methyl chloride solvent to 60 per cent conversion is passed to distillate tower A, from which the overhead is passed to a condenser 3, a separator 4 and a solvent storage tank C, from whence it is withdrawn through a temperature regulator 8 and part is passed directly to a catalyst solution supply tank D and part circulated through aluminium chloride in container E and passed to D. A uniform volume flow into tower A is maintained by a flow recorder controller E in the tower A feed line connected with a split range controller F operating a flow recorder controller valve G to by-pass excess feed to tower A into the intermediate point of tower B or by flow recorder valve H to withdraw overhead from tower B to make up any deficiency in the feed to tower A.