Production of carboxylic acid ester by esterification and apparatus thereof

• US 5,536,856 A
• Filed: 02/23/1994
• Issued: 07/16/1996
• Est. Priority Date: 01/17/1989
• Status: Expired due to Term

• Current Assignee: Davy Process Technologies Limited
• Original Assignee: Davy Process Technologies Limited
• Inventors: Wood, Michael A., Harrison, George E., McKinley, Donald H., Scarlett, John
• Primary Examiner(s): Dees, Jose G.
• Assistant Examiner(s): Carr, Deborah D.
• Application Number:
  US08/200,314
• Time in Patent Office: 874 Days
• Field of Search: 554/168, 554/170, 554/167, 261/108, 261/113, 261/114.5, 560/263, 584/164, 584/163
• US Class Current: 554/164
• CPC Class Codes: B01D 3/163 Plates with valves
• CPC Class Codes: B01D 3/18 with horizontal bubble plates
• CPC Class Codes: B01D 3/20 Bubble caps; Risers for vapour; Discharge pipes for liquid
• CPC Class Codes: B01J 8/226 internally, i.e. the particles rotate within the vessel
• CPC Class Codes: C07C 67/08 by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
• CPC Class Codes: C07C 69/16 of dihydroxylic compounds
• CPC Class Codes: C07C 69/24 esterified with monohydroxylic compounds
• CPC Class Codes: C07C 69/36 Oxalic acid esters
• CPC Class Codes: C07C 69/40 Succinic acid esters
• CPC Class Codes: C07C 69/42 Glutaric acid esters
• CPC Class Codes: C07C 69/52 Esters of acyclic unsaturated carboxylic acids having the esterified carboxyl group bound to an acyclic carbon atom
• CPC Class Codes: C07C 69/58 Esters of straight chain acids with eighteen carbon atoms in the acid moiety
• CPC Class Codes: C07C 69/60 Maleic acid esters; Fumaric acid esters
• CPC Class Codes: C07C 69/704 Citric acid esters
• CPC Class Codes: C07C 69/732 of unsaturated hydroxy carboxylic acids
• CPC Class Codes: C07C 69/76 Esters of carboxylic acids having a carboxyl group bound to a carbon atom of a six-membered aromatic ring
• CPC Class Codes: C07C 69/78 Benzoic acid esters
• CPC Class Codes: C07C 69/82 Terephthalic acid esters

Abstract

Esterification is carried out in a column reactor (14) in which there is a plurality of esterification trays (15) each having predetermined liquid hold-up and containing a charge of a solid esterification catalyst thereon. e.g. an ion exchange resin containing a --SO₃ H and/or --COOH groups. A liquid phase containing the carboxylic acid component, e.g. a fatty acid mixture, flows down the column reactor from one esterification tray to the next downward one against an upflowing alcohol vapour stream, e.g. methanol vapour. Relatively dry alcohol vapour is injected (21) into the bottom of the column reactor. Water of esterification is removed from the top of the column reactor in the vapour stream (26), whilst ester product is recovered (23) from the sump of the reactor. As the liquid flows down the trays it encounters progressively drier alocohol and the esterification equilibrium reaction is driven further and further towards 100% ester formation. A polishing reactor (304) operated under liquid phase conditions may follow the column reactor, the ester-containing product from which is mixed with further alcohol before admission to the polishing reactor.

Claims

1. A continuous process for the production of carboxylic acid esters by reaction of a carboxylic acid component selected from a group consisting of mono-, di- and polycarboxylic acids, anhydrides thereof, and mixtures thereof, and of an alcohol component selected from a group consisting of mono-, di- and polyhydric alcohols, phenols and mixtures thereof, in which the carboxylic acid component and alcohol component are passed in countercurrent through an esterification zone maintained under esterification conditions and containing a solid esterification catalyst selected from particulate ion exchange resins having sulphonic acid groups, carboxylic acid groups or both, (i) wherein the esterification zone comprises a column reactor provided with a plurality of esterification trays mounted one above another, each adapted to hold a predetermined liquid volume and a charge of particles of a solid esterification catalyst thereon, liquid downcomer means associated with each esterification tray adapted to allow liquid phase to pass down the column reactor from that esterification tray but to retain the particles of solid esterification catalyst thereon, and vapor upcomer means associated with each esterification tray adapted to allow vapor to enter that esterification tray from below and to agitate and maintain the suspension of the mixture of liquid and solid esterification catalyst on that esterification tray, each esterification tray having a floor that slopes towards a zone of turbulence under said vapor upcomer means to prevent formation of stagnant zones of particles of catalyst thereon, (ii) wherein the less volatile component of the carboxylic acid component and of the alcohol component is supplied in liquid phase to an upper part of the column reactor above the uppermost esterification tray, while the more volatile component of the carboxylic acid component and of the alcohol component is supplied in vapor form beneath the lowermost one of said plurality of esterification trays, (iii) wherein vapor comprising said more volatile component and water of esterification is recovered from an upper part of the column reactor, and (iv) wherein said carboxylic acid ester is recovered from a lower part of the column reactor.

2. A process according to claim 1, wherein the more volatile component is the alcohol component and the less volatile component is the carboxylic acid component.

3. A process according to claim 1 wherein the alcohol component is an alkanol containing from 1 to about 10 carbon atoms.

4. A process according to claim 3, wherein that the alkanol is methanol.

5. A process according to claim 3 wherein the water content of the alkanol vapour supplied to the column reactor is less than about 5 mole %.

6. A process according to claim 1 wherein the carboxylic acid component is an aliphatic monocarboxylic acid or a mixture thereof.

7. A process according to claim 6, wherein the carboxylic acid component is a mixture of fatty acids.

8. A process according to claim 1 wherein the carboxylic acid component is selected from a group consisting of maleic acid, fumarlc acid, maleic anhydride, a monoalkyl maleate, a monoalkyl fumarate, and mixtures of two or more thereof.

9. A process according to claim 1 wherein the column reactor is operated at a temperature of from about 80°

C. to about 140°

C. and at a pressure of from about 1 bar to about 25 bar.

10. A process according to claim 1 wherein the carboxylic acid ester recovered from a lower part of the column reactor is admixed with further alcohol component and is passed through a fixed bed of a solid esterification catalyst.

11. Apparatus for use in the production of a carboxylic acid ester by reaction of a carboxylic acid component selected from a group consisting of mono-, di- and polycarboxylic acids, anhydrides thereof, and mixtures thereof, and of an alcohol component selected from a group consisting of mono-, di- and polyhydric alcohols, phenols and mixtures thereof, comprising a column reactor provided with a plurality of esterification trays mounted one above another, each adapted to hold a predetermined liquid volume and a charge of particles of a solid esterification catalyst thereon, liquid downcomer means associated with each esterification tray adapted to allow liquid phase to pass down the column reactor from that esterification tray but to retain the particles of solid esterification catalyst thereon, vapor upcomer means associated with each esterification tray adapted to allow vapor to enter that esterification tray from below and to agitate and maintain the suspension of the mixture of liquid and solid esterification catalyst on that esterification tray, each esterification tray having a floor that slopes towards a zone of turbulence under said vapor upcomer means to prevent formation of stagnant zones of particles of catalyst thereon, means for supplying the less volatile component of the carboxylic acid component and of the alcohol component in liquid phase to an upper part of the column reactor above the uppermost esterification tray, means for supplying the more volatile component of the carboxylic acid component and of the alcohol component in vapor form to a lower part of the column reactor below the lowermost esterification tray, means for recovering carboxylic acid ester from a lower part of the column reactor below the lowermost esterification tray, and means for recovering from an upper part of the column reactor above the uppermost esterification tray a vaporous stream comprising said more volatile component and water of esterification.

12. Apparatus according to claim 11, in which said vapor upcomer means comprises a sparger positioned so that, in operation, it will lie below the surface of the mixture of liquid and solid esterification catalyst and so that vapor bubbles emerging therefrom will agitate said mixture of liquid and catalyst.

13. Apparatus according to claim 12, in which the sparger is a ring sparger.

14. Apparatus according to claim 12, in which at least one baffle means is mounted in the vicinity of the sparger to enhance the mixing action thereof.

15. Apparatus according to claim 14, in which inner and outer annular baffle means are positioned in the vicinity of the sparger and define an upflow zone in the region of upflowing vapor bubbles and adjacent downflow zones within and outside the upflow zone.

16. Apparatus according to claim 12, in which the vapor upcomer means of at least one esterification tray is provided with a suckback preventer means.

17. Apparatus according to claim 12, in which a screen means is provided on at least one esterification tray to hinder loss of solid esterification catalyst from that esterification tray via its associated downcomer means.

18. Apparatus according to claim 11 further comprising a reactor containing a fixed bed of a solid esterification catalyst connected downstream from the column reactor and means for admixing additional alcohol component with the carboxylic acid ester component recovered from a lower part of the column reactor prior to entry to the further reactor.