Production and recovery of propylene oxide by plural distillation

• US 3,350,418 A
• Filed: 02/12/1964
• Issued: 10/31/1967
• Est. Priority Date: 02/12/1964
• Status: Expired due to Term

• Current Assignee: Leon E. Bowe, Null, Harold R., Robert C. Binning
• Original Assignee: Leon E. Bowe, Null, Harold R., Robert C. Binning
• Inventors: Bowe, Leon E., Binning, Robert C., Null, Harold R.
• Application Number:
  US04/344,403
• Time in Patent Office: 1,357 Days
• US Class Current: 549/532
• CPC Class Codes: C07D 301/06 in the liquid phase
• CPC Class Codes: C07D 301/32 Separation; Purification

Claims

1. PROCESS FOR THE CONTINUOUS PRODUCTION AND RECOVERY OF PROPYLENE OXIDE WHICH COMPRISES THE DIRECT OXIDATION OF PROPYLENE FEEDSTOCKS WITH MOLECULAR OXYGEN IN A SOLVENT SELECTED FROM THE GROUP CONSISTING OF FULLY ESTERIFIED POLYACYL ESTERS OF POLYHYDROXYALKANES, POLYHYDROXYCYCLOALKANES, POLYGLYCOLS AND MIXTURES THEREOF, WHEREIN SAID ESTERS CONTAIN FROM 1 TO 18 CARBON ATOMS IN EACH ACYL MOIETY AND FROM 2 TO 18 CARBON ATOMS IN EACH ALKYLENE AND CYCLOALKYLENE MOIETY, AND RECOVERING FORMED PROPYLENE OXIDE BY:

(A) DIRECTING AN EFFLUENT STREAM OF THE REACTION MIXTURE FROM A REACTION ZONE THROUGH A COMBINATION LETDOWN DISTILLATION ZONE COMPRISING A FLASHING ZONE FOLLOWED BY A STRIPPING ZONE INTO WHICH THE BOTTOMS FROM SAID FLAHING ZONE IS PASSED, SAID FLASHING ZONE AND STRIPPING ZONE BEING MAINTAINED AT ESSENTAILLY THE SAME TEMPERATURE AS THE OXIDATION REACTION, BUT EACH SUCCESSIVE ZONE BEING MAINTAINED AT PRESSURES SUBSTANTIALLY LOWER THAN IN THE PRECEDING ZONE AND IN SAID REACTION ZONE IN ORDER TO DEPARATE SUBSTANTIALLY ALL OF THE LOW AND INTERMEDIATE BOILING PRODUCTS AS GAS PHASE FROM THE BULK OF THE SOLVENT, (B) PASSING SAID GAS PHASE TO CONDENSING ZONES, FROM WHENCE UNCONDENSED GASES ARE DIRECTED TO AN ABSORBING ZONE INTO WHICH EFFLUENT SOLVENT FROM SAID STRIPPING ZONE IS ALSO PASSED TO ABSORB UNCONDENSED PROPYLENE AND PROPYLENE OXIDE, (C) DIRECTING A SIDE-STREAM OF SAID EFFLUENT SOLVENT IN (B) THROUGH A POLYMERIC RESIDUE HAVING A BOILING POINT ABOVE THAT OF SAID SOLVENT REMOVAL DISTILLATION ZONE WHERE RESIDUE IS REMOVED AS BOTTOMS AND SOLVENT IS DISTILLED OVERHEAD AND RECOMBINED WITH THE SOLVENT BOTTOMS FROM SAID STRIPPING ZONE AND FED TO SAID ABSORBING ZONE, (D) PASSING A COMBINED STREAM OF CONDENSED LIQUIDS FROM SAID CONDENSING ZONES INTO AN ACIDS-SEPARATION DISTILLATION ZONE WHERE ORGANIC ACIDS ARE REMOVED AS BOTTOMS AND PROPYLENE OXIDE, PROPYLENE, PROPANE, ACETALHDEHYDE AND METHY FORMATE ARE DISTILLED OVERHEAD, (E) DIRECTING THE OVERHEAD FROM (D) TO A C3 REMOVAL ZONE DISTILLATION WHERE PROPYLENE AND PROPANE ARE DISTILLED OVERHEAD AND PROPYLENE OXIDE, ACETALDEHYDE AND METHYL FORMATE ARE REMOVED AS BOTTOMS, (F) PASSING SAID BOTTOMS FROM SAID C3 REMOVAL ZONE TO A DISTILLATION ZONE WHERE ACETALDEHYDE IS DISTILLED OVERHEAD AND PROPYLENE OXIDE AND METHYL FORMATE ARE REMOVED AS BOTTOMS, (G) PASSING THE BOTTOMS FROM (F) TO AN ATMOSPHERIC EXTRACTIVE DISTILLATION ZONE USING AS EXTRACTIVE SOLVENT A HYDROCARBON SOLVENT BOILING ABOVE 67*C. AND WHEREIN METHYL FORMATE IS REMOVED OVERHEAD AND SAID EXTRACTIVE SOLVENT CONTAINING PROPYLENE OXIDE IS REMOVED AS BOTTOMS, AND (H) FEEDING THE BOTTOM FROM (G) TO A PROPYLENE OXIDE DISTILLATION REFINING ZONE FROM WHICH PURIFIED PROPYLENE OXIDE IS DISTILLED OVERHEAD AND RECOVERED.