Process for separating ethylene oxide from aqueous solutions

• US 4,437,939 A
• Filed: 11/16/1981
• Issued: 03/20/1984
• Est. Priority Date: 07/17/1981
• Status: Expired due to Fees

• Current Assignee: Scientific Design Company, Inc. (Clariant AG)
• Original Assignee: The Halcon SD Group, Inc.
• Inventors: Bhise, Vijay S., Hoch, Robert
• Primary Examiner(s): BASCOMB JR, WILBUR
• Application Number:
  US06/321,966
• Time in Patent Office: 855 Days
• Field of Search: 260/348.37, 203/43, 203/42, 203/14, 203/91, 203/49, 203/70, 203/67, 203/68, 422/256-260, 196/14.52, 210/634, 210/511, 202/169
• US Class Current: 203/14
• CPC Class Codes: B01D 11/0407 the supercritical fluid acting as solvent for the solute
• CPC Class Codes: C07D 301/32 Separation; Purification

Abstract

Ethylene oxide is extracted from aqueous solutions by carbon dioxide under (near) super-critical conditions and thereafter recovered by distillation at sub-critical conditions. Improved distillation is obtained by adding to the carbon dixoide a gas (or gases) which adjust the critical temperature of the gas mixture of the top of the distillation column within the range of about 32° C. to about 75° C. Preferred gases are the saturated hydrocarbons, particularly propane, n-butane, isobutane and pentane.

Claims

1. In a process for recovering ethylene oxide from aqueous solutions wherein carbon dioxide at near-critical or super-critical conditions extracts ethylene oxide and thereafter the extracted ethylene oxide is separated from the carbon dioxide by distillation at sub-critical conditions, the improvement comprising adding an amount of a gas or gases to said carbon dioxide sufficient to provide a critical temperature for the carbon dioxide-ethylene oxide-added gas mixture at the top of said distillation column between 32°

C. and 75°

C.

2. A process of claim 1 wherein said added gas is at least one member selected from the group consisting of propane, n-butane, isobutane, pentane, and halogenated refrigerants and the amount added is about 0.01-0.5 mols per mols of carbon dioxide of the top of said distillation column.

3. A process of claim 2 wherein said added gas is n-butane and the amount added is about 0.05-0.15 mols per mol of carbon dioxide at the top of said distillation column.

4. A process of claim 2 wherein said added gas is propane and the amount added is about 0.1-0.3 mols per mol of carbon dioxide at the top of said distillation column.

5. A process of claim 2 wherein said added gas is n-pentane and the amount added is about 0.01-0.1 mols per mol of carbon dioxide at the top of said distillation column.

6. A process of claim 2 wherein said added gas is a halogenated refrigerant and the amount added is about 0.1-0.3 mols per mol of carbon dioxide at the top of said distillation column.