WO2009129355A1

WO2009129355A1 - Integrated process for the production of chlorinated epoxides such as epichlorohydrin

Info

Publication number: WO2009129355A1
Application number: PCT/US2009/040736
Authority: WO
Inventors: Anna Forlin; Ernesto Occhiello
Original assignee: Dow Global Technologies Inc.
Priority date: 2008-04-18
Filing date: 2009-04-16
Publication date: 2009-10-22

Abstract

A process and system for the production of chlorinated epoxides such as epichlorohydrin. The production of epichlorohydrin includes, for example, dehydrogenation of propane to form hydrogen and propylene, chlorination of the propylene to form allyl chloride, production of hydrogen peroxide using the hydrogen from the dehydrogenation, and epoxidation of the allyl chloride using the hydrogen peroxide to form epichlorohydrin.

Description

INTEGRATED PROCESS FOR THE PRODUCTION OF CHLORINATED EPOXIDES

SUCH AS EPICHLOROHYDRIN

BACKGROUND OF THE INVENTION

The present invention relates to a process for producing chlorinated epoxides such as for example epichlorohydrin and other related chlorinated epoxides.

Epichlorohydrin is a well known commercial product. Epichlorohydrin is typically produced by processes that include cracking of petroleum fractions to form propylene. However, it would be desirable to industry to have other routes to epichlorohydrin that do not employ cracking as it would enable use of different feed stock.

SUMMARY OF THE INVENTION

The present invention provides a solution to one or more of the problems and disadvantages encountered by the use of previously known processes for preparing epichlorohydrin.

One aspect of the present invention is a process for producing epichlorohydrin comprising: (a) dehydrogenating an alkane such as propane to form hydrogen and the resulting alkene such as propylene; (b) chlorinating the alkene from step (a) to form an unsaturated chloride; (c) producing hydrogen peroxide from oxygen and hydrogen from step (a); and (d) epoxidizing the unsaturated chloride from step (a) using the hydrogen peroxide from step (c) to form a chlorinated epoxide. The alkane (for example, propane) to be hydrogenated may be obtained from sources other than petroleum fractions, such as from natural gas.

It is envisioned that the process of the present invention can be performed using hydrocarbons other than propylene to form different epoxidized products. The starting material for the present invention process thus may be for example butane, pentane, hexane, heptane, higher alkanes up to about 10 carbon atoms, and mixtures thereof. However, epichlorohydrin is currently perhaps the mostly desirable product.

Another aspect of the present invention is an integrated system for the production of epichlorohydrin, comprising: (a) an alkane dehydrogenation unit to form hydrogen and an alkene; (b) a chlorination unit for chlorinating the alkene from the alkane dehydrogenation unit (a) to form a chlorinated alkene; (c) a hydrogen peroxide unit to produce hydrogen peroxide from oxygen the and hydrogen from the dehydrogenation unit (a); and (d) an epoxidation unit for epoxidizing the chlorinated alkene from the alkane dehydrogenation unit (a) using the hydrogen peroxide from the hydrogen peroxide unit (c) to form a chlorinated epoxide.

Still another aspect of the present invention is a process for the manufacture of an integrated system for the production of epichlorohydrin, comprising: (a) providing an alkane dehydrogenation unit that produces hydrogen and an alkene; (b) providing a chlorination unit for chlorinating the alkene from the dehydrogenation unit to form a chlorinated alkene; (c) providing a hydrogen peroxide unit to produce hydrogen peroxide from oxygen and the hydrogen from the dehydrogenation unit; and (d) providing an epoxidation unit for epoxidizing the chlorinated alkene from the chlorination unit using the hydrogen peroxide from the hydrogen peroxide unit to form a chlorinated epoxide.

The present invention provides a number of advantages. Significantly, the present invention permits manufacture of epichlorohydrin, and other chlorinated epoxides, without the need for cracking of petroleum fractions. Thus natural gas, for example, can be used as feedstock.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the present invention, the drawings show embodiments of the present invention which are presently preferred. However, it should be understood that the present invention is not limited to the precise arrangements and instrumentalities shown in the drawings. In the accompanying drawings, like reference numerals are used to denote like parts throughout the several drawings.

Figure 1 is a simplified block flow diagram illustrating the process of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the practice of the present invention, propane or other light alkane is dehydrogenated in a dehydrogenation unit to form hydrogen and an alkene such as propylene. This dehydrogenation can be performed using conventional techniques. For example, the dehydrogenation can be run in a conventional dehydrogenation unit operated at a temperature of about 450 degrees Centigrade (⁰C) to about 800⁰C at atmospheric (14 psia) or slightly above atmospheric pressure while the feedstock flows through or over a catalyst bed so that the feedstock contacts the catalyst. One such dehydrogenation process is described in U.S. Patent Application Publication No. 2002/0016520, incorporated herein by reference. A variety of catalyst bed designs for the dehydrogenation unit may be employed including fixed and flowing beds. The space velocity of feedstock over the catalyst can vary depending on temperature, type of catalyst, and other process variables.

Typically the dehydrogenation unit contains a catalyst known in the art such as noble metal catalysts described in U.S. Patent Nos. 4,866,928 and 4,786,625, or chromium oxide catalyst as described in U.K. patent No. 2,162,082, all of which are incorporated herein by reference. For example, catalysts based on gallium oxide and platinum supported on alumina can be employed. The catalyst may include one or more promoters or co-catalysts.

The alkane to be hydrogenated may be obtained from sources other than petroleum fractions, such as from natural gas. Other dehydrogenation processes include, but are not limited to, the use of packed bed membrane reactors and dehydrogenation using palladium composite membrane reactors, such as are known in the art. It should be appreciated that the particular type of dehydrogenation unit employed is not critical so long as a stream of alkene is produced. The effluent from the dehydrogenation unit (or "reactor") includes hydrogen and an alkene such as propylene, and may further contain unreacted alkane, by-products, or other components entrained in the feedstock. The hydrogen is separated from the alkene, with the hydrogen sent to the hydrogen peroxide unit and the alkene sent to the chlorination unit.

Thus the alkene such as propylene from the dehydrogenation is chlorinated to form a chlorinated alkene such as allyl chloride. The chlorination process can be accomplished in a conventional chlorination unit for production of, for example, allyl chloride. In general, the alkene and chlorine gas are fed to the chlorination unit. Conversion of the alkene to chlorinated alkene is a facile reaction, with hydrogen chloride being formed as a co-product. Hydrogen chloride is separated from the chlorinated alkene with the chlorinated alkene being sent to an epoxidation unit. The chlorination reaction may be run in the presence or absent of a catalyst designed for such use. The chlorination reaction can be run under conditions typical of such reactions. Representative examples of references that describe such chlorination include, but are not limited to, U.S. Patent Nos. 4,319,062 and 5,504,266, including references cited therein, all of which are incorporated herein by reference. The particular type of chlorination unit employed is not critical to the practice of the present invention. The allyl chloride product produced may be used immediately or stored for use later in a subsequent epoxidation process.

Hydrogen peroxide is used for the epoxidation of allyl chloride. In one embodiment, hydrogen peroxide is produced at least in part from the hydrogen produced from the dehydrogenation reaction and oxygen. The production of hydrogen peroxide is well known. The production of the hydrogen peroxide can be conducted using conventional techniques. In general, hydrogen, oxygen, and a catalyst and co-catalyst are charged to a hydrogen peroxide reactor where hydrogen peroxide formation occurs. The hydrogen and oxygen are used in quantities that provide a non-explosive mixture. The catalyst can also be present as a fixed bed, trickle bed, or the like. In one embodiment, the hydrogen peroxide is made in solution, in either an aqueous solution, an organic solvent, or an aqueous solution containing an organic solvent, by contacting oxygen and hydrogen gases. For example, U.S. Patent No. 4,335,092, incorporated herein by reference, describes use of a methanol- water medium to prepare hydrogen peroxide. Also, WO 03/014014, incorporated herein by reference, describes a titanium-silicalite catalyst and process for use in the preparation of hydrogen peroxide and WO 2006/108748, incorporated herein by reference, describes another noble metal catalyst used in a liquid reaction medium. Additional references that disclose hydrogen peroxide production include but are not limited to U.S. Patent Nos. 5,840,934 and 4,336,238; U. S. Patent Publication No. 2003/0083510; EP 0 978 316; and EP 0 049 806; all of which are incorporated herein by reference. Known catalysts can be used for the reaction in the production of the hydrogen peroxide. These catalysts for hydrogen peroxide production may contain one or more elements of the Groups VIII and/or Ib of the periodic system, especially elements from the series Ru, Rh, Pd, Ir, Pt and Au, with Pd and Pt particularly preferred. The catalytically active element or elements are usually bound to a particulate carrier, but can also be made as a coating with sufficiently great active surface on a monolithic carrier with channels, or on other flat carriers. Carrier-bound noble metal catalysts are particularly preferred as these catalysts are suitable for use in trickling bed reactors as a fixed bed with predetermined particle size. The particle size of suitable carriers is in the general range of about 0.01 millimeter (mm) to about 5 mm, and especially in the range of about 0.05 mm to about 2 mm. The noble metal content in the carrier/catalyst combination is generally from about 0.01 percent by weight to about 10 percent by weight. Suitable carrier materials useful in the present invention, other than activated carbon, are water-insoluble oxides; mixed oxides; sulfates; phosphates; silicates of alkaline earth metals, Al, Si, Sn; metals of the third to sixth subgroups (Ilia to Via); and mixtures thereof. Activated carbons are generally preferred carriers, but in selecting the carrier care should be taken that the carrier has the minimum effect of decomposing hydrogen peroxide. Of the oxides useful as the carrier material, SiO₂, Al₂O₃, SnO₂, TiO₂, ZrO₂, Nb₂O₅, and Ta₂O₅, are preferred; and, of the sulfates, barium sulfate is preferred.

Thus, representative examples of suitable catalysts include catalysts composed of palladium, platinum, alloyed or non-alloyed combinations of palladium, platinum, with or without promoters such as silver or gold, and so on, which can be present on a support material such as silica, alumina, titanium dioxide, zirconium dioxide, and zeolites where the catalyst may be in the form of powder, extrudates, granules, and so on.

The particular process used to make the hydrogen peroxide used in the present invention is not critical. The hydrogen peroxide can be prepared in a discrete hydrogen peroxide production unit with hydrogen peroxide with the hydrogen peroxide separated and sent to the chlorination unit. Conversely, the hydrogen peroxide can be made in situ within the chlorination unit where hydrogen from the dehydrogenation unit is fed directly to the chlorination unit for in situ production of the hydrogen peroxide.

The chlorinated alkene such as allyl chloride is epoxidized in an epoxidation unit using the hydrogen peroxide to form an epoxidized chlorinated hydrocarbon such as epichlorohydrin. Epoxidation of chlorinated alkenes such as allyl chloride is well known, such as described in U.S. Patent No. 6,350,888, incorporated herein by reference. In the practice of the present invention, organic peroxides are not, however employed as oxidizing agents. The reaction can be conducted in the presence of a catalyst, such as a titanium silicalite catalyst, such as described in EP 0 230 949 and U.S. Patent No. 6,372,924, incorporated herein by reference. In general, an aqueous solution containing hydrogen peroxide and the chlorinated alkene, optionally containing an organic solvent especially alcohols such as methanol, ethanol, and butanol, are introduced periodically or continuously into an epoxidation unit in the presence of the catalyst. The pH may be monitored and controlled to optimize the reaction. Typically, the temperature is maintained at about -10 ⁰C to about 100 ⁰C, more frequently from about 20 ⁰C to about 70 ⁰C. The catalyst can be suspended in the reaction medium or the reactor can be operated in fixed bed mode, or other mode. Any ratio of hydrogen peroxide to chlorinated alkene can be employed; however, typically the ratio is about one or greater, and more typically, in the range from about 1:1 to about 10:1. If used, the amount of solvent is typically about 1 to about 20 percent by weight. Other catalysts that can be employed included titanium zeolite catalysts such as described in U.S. Patent No. 6,699,812, incorporated herein by reference.

It is envisioned that the process of the present invention can be performed using hydrocarbons other than propylene to form different epoxidized products. The starting material can thus be butane, pentane, hexane, heptane, higher alkanes up to about 10 carbon atoms, and mixtures thereof. However, epichlorohydrin is the currently perhaps the mostly desirable product; thus, propane is currently the most desirable starting material.

One embodiment of the present invention is illustrated with reference to Figure 1. In Figure 1 there is shown, in general, a process flow and integrated system for preparing epichlorohydrin, generally indicated by numeral 10, including for example a propane dehydrogenation system 20, a hydrogen peroxide production system 30, an allyl chloride production system 40, and an epichlorohydrin production system 50.

The propane dehydrogenation system 20 comprises a feed stream 21 of propane wherein the propane is dehydrogenated to form a propylene stream 22 and a hydrogen stream 23 exiting the system 20. In addition, a stream 24 containing other hydrocarbons exits the system 20 and stream 24 is recovered or forwarded to another processing system.

The hydrogen peroxide production system 30 is connected directly or indirectly to the dehydrogenation system 20 via conduit stream 23 for conducting at least part of the effluent stream 23 from the dehydrogenation system 20 to the hydrogen peroxide production system 30. The effluent stream 23 forms the feed stream to the hydrogen peroxide production system 30. An oxygen feed stream 31 is fed into the hydrogen peroxide production system 30 and reacted with the hydrogen feed stream 23 to form hydrogen peroxide which exits the system 30 via stream 32. In addition, a purge stream 33 may be used to purge excess oxygen and other non-reacted components from the system 30. The hydrogen peroxide stream 32 is fed into the epichlorohydrin production system 50 as discussed below. The allyl chloride production system 40 is connected directly or indirectly to the propane dehydrogenation system 20 via conduit stream 22 for conducting at least part of the effluent stream 22 from the dehydrogenation system 20 to the allyl chloride production system 40. The propylene stream 22 from the propane dehydrogenation system 20 is fed to the allyl chloride production system 40 wherein allyl chloride is synthesized from the propylene with the propylene feed 22 into the system 40 is reacted with a chlorine feed stream 41 in the system 40. The effluent stream 22 forms the feed stream to the allyl chloride production system 40. The allyl chloride produced in the system 40 exits the system 40 as allyl chloride product stream 43. A hydrogen chloride vent stream 42 exits the system 40 while an allyl choride product stream 43 is sent to the epichlorohydrin production system 50. In addition, a stream 44 of other undesired chlorinated hydrocarbons is recovered or forwarded to another processing system.

The epichlorohydrin production system 50 is connected directly or indirectly to the allyl chloride production system 40 via conduit stream 43 for conducting at least part of the effluent stream 43 from the system 40 to the epichlorohydrin production system 50. In addition, the epichlorohydrin production system 50 is connected directly or indirectly to the hydrogen production system 30 via conduit stream 32 for conducting at least part of the effluent stream 32 from the system 30 to the epichlorohydrin production system 50. The allyl chloride stream 43 from the allyl chloride system 40 is fed to the epichlorohydrin production system 50 as one feed stream while the hydrogen peroxide stream 32 from the hydrogen peroxide production system 30 is fed to the epichlorohydrin production system 50 as another feed stream. Epichlorohydrin is synthesized from the allyl chloride and hydrogen peroxide feed streams in the system 50. The effluent stream 43 forms one feed stream to the epichlorohydrin production system 50 and the effluent stream 32 forms the other feed stream to the epichlorohydrin production system 50. The epichlorohydrin product produced in the system 50 exits the system 50 as epichlorohydrin product stream 51. Other oxygen, chlorinated hydrocarbons and unreacted components exit the system 50 via vent stream 52 while the epichlorohydrin product stream 51 is recovered or sent to another processing system if desired.

Further modifications and alternative embodiments of the present invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the manner of carrying out the present invention. It is to be understood that the forms of the present invention herein shown and described are to be taken as illustrative embodiments. Equivalent elements or materials may be substituted for those illustrated and described herein; and certain features of the present invention may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the present invention.

Claims

WHAT IS CLAIMED IS:

1. A process for the production of a chlorinated epoxide, comprising: (a) dehydrogenating an alkane to form hydrogen and an alkene; (b) chlorinating the alkene from step (a) to form an unsaturated chloride; (c) producing hydrogen peroxide from oxygen and the hydrogen from step (a); and (d) epoxidizing the unsaturated chloride from step (a) using the hydrogen peroxide from step (c) to form a chlorinated epoxide.

2. The process of claim 1, wherein the alkane is propane and the alkene is propylene.

3. The process of claim 1, wherein step (c) is performed in situ during the epoxidizing in step (d).

4. The process of claim 1, wherein the production of hydrogen peroxide step (c) and/or the epoxidizing step (d) is conducted in the presence of a catalyst.

5. The process of claim 1, wherein the production of hydrogen peroxide occurs in an aqueous medium, optionally containing an organic solvent.

6. The process of claim 1, wherein the chlorinated epoxide is epichlorohydrin.

7. An integrated system for the production of a chlorinated epoxide, comprising: (a) an alkane dehydrogenation unit to form hydrogen and an alkene; (b) a chlorination unit for chlorinating the alkene from the alkane dehydrogenation unit (a) to form a chlorinated alkene; (c) a hydrogen peroxide unit to produce hydrogen peroxide from oxygen and hydrogen from the dehydrogenation unit (a); and (d) an epoxidation unit for epoxidizing the chlorinate alkene from chlorination unit (b) using the hydrogen peroxide from the hydrogen peroxide unit (c) to form the chlorinated epoxide.

8. The system of claim 7, wherein the alkane is propane and the alkene is propylene.

9. The system of claim 7, wherein hydrogen peroxide unit (c) is operated within the epoxidation unit (d).

10. The system of claim 7, wherein the hydrogen peroxide unit and/or the epoxidation unit operates using a catalyst.

11. The system of claim 7, wherein hydrogen peroxide unit operates using an aqueous medium, optionally containing an organic solvent.

12. The system of Claim 7, wherein the chlorinated epoxide is epichlorohydrin.

13. A process for the manufacture of an integrated system for the production of epichlorohydrin, comprising: (a) providing an alkane dehydrogenation unit that produces hydrogen and an alkene; (b) providing a chlorination unit for chlorinating the alkene from the dehydrogenation unit to form a chlorinated alkene; (c) providing a hydrogen peroxide unit to produce hydrogen peroxide from oxygen and the hydrogen from the dehydrogenation unit; and (d) providing an epoxidation unit for epoxidizing the chlorinated alkene from the chlorination unit using the hydrogen peroxide from the hydrogen peroxide unit to form a chlorinated epoxide.

14. The process of claim 13, wherein the alkane is propane and the alkene is propylene.

15. The process of claim 13, wherein the hydrogen peroxide unit is within the epoxidation unit for in situ production of hydrogen peroxide.

16. The process of claim 13, wherein the hydrogen peroxide unit and/or the epoxidation unit uses a catalyst.

17. The process of claim 13, wherein the hydrogen peroxide unit uses an aqueous medium, optionally containing an organic solvent.