Patent GB-624445-A (GB)
Title: Improvements relating to the production of butadiene
IPC: C07C7/05
Filed: 1946-10-08
Abstract: <PICT:0624445/III/1> Butadiene is separated from other products accompanying its manufacture by the pyrolysis of cyclohexane by preparing at atmospheric pressure a solution of the mixed products in cyclohexane or in a cyclohexane/benzene mixture, fractionally distilling the solution at atmospheric pressure to remove an overhead fraction, comprising the light ends and some butadiene, which is scrubbed with cyclohexane-or the cyclohexane/benzene mixture-the resulting solution being admixed with the solution entering the distillation column; an intermediate fraction consisting of butadiene and cyclohexane is taken off from the distillation column and fractionally distilled to separate the two components.  As shown, gas or a solution from the pyrolysis reaction is passed through line 3 into a scrubber 1, the gas passing upwards together with the head fraction comprising light ends and butadiene from distillation column 5, in countercurrent with a descending current of cyclohexane introduced at the top through cooler 23 from receiver 9.  A gas fraction is taken off from the scrubber to condenser 16, condensed cyclohexane being passed to receiver 9.  The side fraction from column 5-which operates at atmospheric pressure-consisting of a butadiene solution in cyclohexane, is passed to fractionation column 10, and the botton fraction consisting of cyclohexane to receiver 9. The head fraction of butadiene from column 10, preferably operating above atmospheric pressure, is passed to condenser 11 from which a portion is cycled back as reflux, and the bottom fraction of cyclohexane is passed to receiver 9.  A mixture of cyclohexane with sufficient benzene to approximate to, or be greater than, the eutectic mixture may replace the cyclohexane.  Instead of taking a side fraction from column 5, the bottom fraction may be passed in part to a third distillation column and in part to column 10.  Where column 10 is not operated at sufficiently high pressure, condenser 11 employs refrigeration.ALSO:<PICT:0624445/IV (b)/1> Butadiene is separated from other products accompanying its manufacture by the pyrolysis of cyclohexane by preparing at atmospheric pressure a solution of the mixed products in cyclohexane or in a cyclohexane/benzene mixture, fractionally distilling the solution at atmospheric pressure to remove an overhead fraction comprising the light ends and some butadiene which is scrubbed with cyclohexaneor the cyclohexane/benzene mixture-the resulting solution being admixed with the solution entering the distillation column; an intermediate fraction consisting of butadiene and cyclohexane is taken off from the distillation column and fractionally distilled to separate the two components.  As shown, gas or a solution from the pyrolysis reaction is passed through line 3 into a scrubber 1, the gas passing upwards together with the head fraction comprising light ends and butadiene from distillation column 5, in countercurrent with a descending current of cyclohexane introduced at the top through cooler 23 from receiver 9.  A gas fraction is taken off from the scrubber to condenser 16, condensed cyclohexane being passed to receiver 9.  The side fraction from column 5-which operates at atmospheric pressure-consisting of a butadiene solution in cyclohexane, is passed to fractionation column 10, and the bottom fraction consisting of cyclohexane to receiver 9.  The head fraction of butadiene from column 10, preferably operating above atmospheric pressure, is passed to condenser 11 from which a portion is cycled back as reflux, and the bottom fraction of cyclohexane is passed to receiver 9.  A mixture of cyclohexane with sufficient benzene to approximate to, or be greater than, the eutectic mixture may replace the cyclohexane.  Instead of taking a side fraction from column 5, the bottom fraction may be passed in part to a third distillation column and in part to column 10. Where column 10 is not operated at sufficiently high pressure, condenser 11 employs refrigeration.