Improvements in or relating to propylene polymerization with hf-bf

摘要

C12 - C15 polymers of propylene are produced by contacting with an HF - BF3 catalyst under pressure sufficient to maintain the propylene and the HF in liquid phase and employing a sufficiently large amount of an inert diluent in which HF is soluble ao that the HF is completely dissolved in the diluent-propylene mixture during polymerization. The diluent, e.g. propane, may be passed through a column of HF and the resulting solution intimately mixed with the propylene and the BF3 component, and polymerization effected under a pressure of 300 to 600 lbs./sq. in. at a temperature of 40 DEG to 140 DEG F. The conversion to detergent polymers is from 40 to 100 per cent. In the apparatus shown, propylene is introduced through line 10 to mixer 12 where it is admixed with BF3, from line 15, and HF (preferably in solution in propane) introduced through line 16. Propane is passed through line 20 and at least a portion passes in liquid phase through the HF in vessel 19 and thence to line 16. The mixture from 12 is passed into the reaction chamber 14 provided with cooling coils 16a. The effluent then proceeds to the settler 25 where any complex may separate out. The product stream is withdrawn into heat exchanger 31 where it is heated to about 250 DEG F. before being led into depropanizer tower 32. This may be operated at a pressure of about 260 psig. with a top temperature of 180 DEG F. and a bottom temperature of 480 DEG F. The polymer passes by line 78 through heat exchanger 31 and thence through one or more bauxite treaters 79 to gasoline fractionating tower 81 which may operate at about 20 psig. with a bottom temperature of 500 DEG F. The overhead fraction, consisting of gasoline-boiling range polymers, is condensed in cooler 83, collected in receiver 84 and withdrawn through line 87. Polymer fractions of higher boiling point are passed to fractionating tower 89 which may operate at 350 mm. Hg pressure with a top temperature of 365 DEG F. and a bottom temperature of 550 DEG F. C18 and heavier polymers are withdrawn through line 91 and the overhead is condensed in cooler 92 and collected in receiver 93. A part of this condensate is returned by pump 94 and line 95 for reflux in tower 89 and the net C12 - C15 polymers are withdrawn through line 96. In the example about 2 volumes of propane are used per 3 volumes of propylene. The catalyst may contain 80-50 mol. per cent. HF, and may be in amounts of 3 to 4 mol. per cent. based on propylene charged to give a total weight per cent. of HF in the total hydrocarbon charge of about 0.5. BF3 and other gas must not accumulate in the reaction system and lines 28 and 29 are provided for their withdrawal. From the depropanizing zone 32, the overhead is separated into a propane fraction, a gas fraction, a BF3 and an HF fraction and the propane and catalyst components may be recycled. Alternatively to dissolving the HF in propane, homogeneity may be maintained by other means, e.g. reacting HF with a portion of the propylene to form propylene fluoride which liberates HF in the mixer or reaction zones.