×

Production of isocyanate using chlorine recycle

  • US 6,010,612 A
  • Filed: 10/01/1997
  • Issued: 01/04/2000
  • Est. Priority Date: 11/22/1993
  • Status: Expired due to Fees
First Claim
Patent Images

1. A process for producing an isocyanate from chlorine gas produced by the electrochemical conversion of anhydrous hydrogen chloride to chlorine gas, comprising the steps of:

  • (a) supplying chlorine to a phosgene generator through a first inlet supply line and supplying carbon monoxide to the phosgene generator through a second inlet supply line, wherein the chlorine and the carbon monoxide react in the phosgene generator to produce phosgene;

    (b) supplying the phosgene from the phosgene generator to an isocyanate reactor;

    (c) supplying an amine to the isocyanate reactor, wherein the amine reacts with the phosgene in the isocyanate reactor to produce an isocyanate and anhydrous hydrogen chloride;

    (d) supplying the anhydrous hydrogen chloride to an anode-side inlet of an electrochemical cell, wherein the electrochemical cell comprises a cation-transporting membrane, an anode disposed in contact with one side of the membrane and a cathode disposed in contact with the other side of the membrane;

    (e) applying a voltage to the electrochemical cell so that the anode is at a higher potential than the cathode, and so that;

    (i) the anhydrous hydrogen chloride is oxidized at the anode to produce chlorine gas and protons,(ii) the chlorine gas is released from an anode-side outlet of the cell,(iii) the protons are transported through the membrane of the cell, and(iv) the transported protons are reduced at the cathode of the cell; and

    (f) supplying the chlorine gas released from the anode-side outlet to the phosgene generator.

View all claims
  • 3 Assignments
Timeline View
Assignment View
    ×
    ×