GB1004679A - Recovery of hydrogen chloride and unreacted propylene from propylene chlorination reaction product mixture - Google Patents

Abstract

<PICT:1004679/C4-C5/1> Propylene is recovered from the reaction mixture from the thermal chlorination of propylene by (A) separating the organic chlorides from the mixture, and (B) bringing the resulting mixture of HCl and propylene into contact with azeotropic aqueous HCl solution to absorb the HCl, with consequent separation of some of the propylene; (C) stripping residual propylene from the resulting aqueous solution and recycling to step (B); (D) separating anhydrous HCl from the rich aqueous solution leaving an azeotropic aqueous HCl solution which is fed back to step (B). In the Figure, the reaction product mixture, having the proportions 1 mol. allyl choloride, 1 to 6.7 mol. propylene, and 0.5 to 1.7 mol. HCl, passes from reactor 12 through cooler 14 via line 15 to fractionating column 16, whence crude allyl chloride leaves at 18. Propylene reflux, which may be added in the proportion of 100 to 400 mol. per 90 mol. allyl chloride, enters via line 17, and a mixture of propylene and HCl is passed via line 19 to absorber 20, which may operate adiabatically, where it meets water from line 21 and azeotropic aqueous HCl solution from line 29. Wet propylene vapour leaves at 22. Rich aqueous HCl solution containing some propylene passes via line 23 t propylene stripper 24 which is heated, and the stripped propylene vapour is returned via 25 to absorber 20. The rich HCl solution passes via 26 to HCl stripper 27. Anhydrous HCl leaves at 28, and the residual azeotropic HCl solution is recycled via line 29 to absorber 20. The wet propylene from 22 is caustic scrubbed, compressed and condensed, and is recycled via 11 to reactor 12 or introduced as reflux into column 16.ALSO:<FORM:1004679/C2/1> Alkyl chloride formed by the thermal chlorination of propylene is separated from HCl and propylene in the reaction product mixture. In the figure, the reaction product mixture having the proportions 1 mol. allyl chloride, 1 to 6-7 mol. propylene, and 0.5 to 1.7 mol. HCl, passes from reactor 12 through cooler 14 via line 15 to fractionating column 16, whence crude allyl chloride leaves at 18. Propylene reflux, which may be added in the proportion of 100 to 400 mol. per 90 mol. allyl chloride, enters via line 17. A mixture of propylene and HCl passes via line 19 to apparatus for recovery of the HCl and the propylene; recovered propylene may be recycled via 11 to reactor 12 or introduced as reflux into column 16.ALSO:<PICT:1004679/C1/1> Hydrogen chloride and propylene are recovered from the reaction mixture from the thermal chlorination of propylene by (A) separating the organic chlorides from the mixture, and (B) bringing the resulting mixture of HCl and propylene into contact with azeotropic aqueous HCl solution to absorb the HCl, with consequent separation of some of the propylene; (C) stripping residual propylene from the resulting aqueous solution and recycling to step (B); (D) separating anhydrous HCl from the rich aqueous solution leaving an azeotropic aqueous HCl solution which is fed back to step (B). In the Figure, the reaction product mixture, having the proportions 1 mol. allyl chloride, 1 to 6.7 mol. propylene, and 0.5 to 1.7 mol. allyl chloride, 1 to 6.7 mol. propylene, and 0.5 to 1.7 mol. HCl, passes from reactor 12 through cooler 14 via line 15 to fractionating column 16, whence crude allyl chloride leaves at 18. Propylene reflux, which may be added in the proportion of 100 to 400 mol. per 90 mol. allyl chloride, enters via line 17, and a mixture of propylene and HCl is passed via line 19 to absorber 20, which may operate adiabatically, where it meets water from line 21 and azeotropic aqueous HCl solution from line 29. Wet propylene vapour leaves at 22. Rich aqueous HCl solution containing some propylene passes via line 23 to propylene stripper 24 which is heated, and the stripped propylene vapour is returned via 25 to absorber 20. The rich HCl solution passes via 26 to HCl stripper 27. Anhydrous HCl leaves at 28, and the residual azeotropic HCl solution is recycled via line 29 to absorber 20. The wet propylene from 22 is caustic scrubbed, compressed and condensed, and is recycled via 11 to reactor 12 or introduced as refluxed into column 16.