Process for the Chlorination of Ethane

Home , Ethane

Europa,schesP_ MM M II II II MINI M IMIMI Ml J European Patent Office ^ _ _ _ _ _ © Publication number: 0 453 502 B1 Office europeen desj brevets

@ Date of filing: 27.11.89

Q») PROCESS FOR THE CHLORINATION OF ETHANE.

® Priority: 13.01.89 US 297087 © Proprietor: Stauffer, John E. 6 Pecksland Road @ Date of publication of application: Greenwich 30.10.91 Bulletin 91/44 Connecticut 06830 (US)

© References cited: © Representative: Kugele, Bernhard GB-A- 794 378 US-A- 2 447 410 NOVAPAT-CABINET CHEREAU, US-A- 2 547 139 US-A- 3 420 901 9, Rue du Valais US-A- 3 642 918 US-A- 4 192 822 CH-1202 Geneve (CH)

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Note: Within nine months from the publication of the mention of the grant of the European patent, any person ® may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition CL shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee LU has been paid (Art. 99(1) European patent convention). Rank Xerox (UK) Business Services (3. 10/3.09/3.3.3) 1 EP 0 453 502 B1 2

Description In order to circumvent the shortcomings of existing technology, numerous attempts have been This application is a continuation-in-part of made to oxychlorinate ethane by cost-effective copending application Serial No. 040,838 filed April means. Methods, for example, employing ox- 20, 1987, which in turn is a continuation-in-part of 5 yhalogenation and related technology are de- copending application Serial No. 842,189 filed scribed in U.S. Patent Nos. 3,470,260, 2,334,033, March 21, 1986, now abandoned. 2,498,546, 3,173,962, 3,345,422, 4,000,205, 4,020,117, 4,284,833, 4,375,569, 4,386,228, Field of the Invention 4,446,249, 4,461,919, and 4,467,127. 10 U.S. Patent No 2,447,410 discloses a process This invention relates to a novel method of for the manufacture of chlorinated compounds by chlorinating ethane using hydrogen chloride, chlo- the pyrolysis of carbon chlorides and, more par- rine, or any proportion of these two reagents ticularly, a process for the concurrent manufacture HCI/Cb as the chlorinating agent. The principal of tetrachloroethylene and ethyl chloride by com- products are ethyl chloride (C2H5CI) and unsatu- 15 bining the thermal decomposition of hexach- rated chlorinated hydrocarbons with two carbon loroethane, into an admixture of chlorine and atoms. The latter include vinyl chloride tetrachloroethylene, and the reaction of ethane with (CH2=CHCI), vinylidene chloride (CH2=CCI2), chlorine. In this process, there occurs a net produc- trichlorethylene (CHCI = CCI2), and perch- tion of hydrogen chloride. loroethylene (CCI2=CCI2). By adjusting the pro- 20 U.S. Patent N° 3.420.901 discloses the cata- cess conditions, the output of vinyl chloride can be lytic oxychlorination of alkanes and alkenes, in par- maximized. ticular ethylene, with hydrogen chloride oxygen. It is an object of the present invention to pro- Background of the Invention vide a method for the chlorination of ethane that 25 overcomes the disadvantages of the conventional Description of the Prior Art methods. It is also an object to provide a method of the The foregoing products have traditionally been kind described which includes endothermic and prepared from more expensive sources of hydro- exothermic reactions, namely substitution chlorina- carbons. Dating back to the early part of this cen- 30 tion and dissociation, that are carried out in tandem tury, the large scale production of vinyl chloride, such that the overall energy requirements can be trichloroethylene and perchloroethylene com- closely balanced. menced with the use of acetylene. Produces from These and other objects, features and advan- calcium carbide, which consumes large quantities tages of the invention will be apparent from the of electric energy, acetylene remained a relatively 35 following description and the accompanying draw- expensive raw material. When the ethylene oxych- ings in which: lorination process was developed during the 1950's, acetylene was supplanted by less costly Brief Description of the Drawing ethylene as a feed stock for chlorinated hydrocarbons. Up to the present time practically all 40 The FIGURE is a diagrammatic representation chlorinated ethane/ethylene products have been of preferred means for operating the present derived from ethylene. chlorination method including a shell and tube cata- Although ethylene is produced in large quan- lytic reactor in series with a thermal reactor with tities by world-scale plants, its cost is necessarily means for recycling and for withdrawal of chlorinat- higher than the price of ethane from which it is 45 ed product and fractionation. preferentially made. Contributing to ethylene's cost is the necessity of employing complex, high-tem- Summary of the Invention perature cracking processes with inherent ineffi- ciencies. Therefore, there would be a significant The invention concerns a process for the advantage of substituting ethane for ethylene in the 50 chlorinstion of ethane using hydrogen chloride as manufacture of chlorinated ethane/ethylene pro- the source of chlorine and avoiding net production vided flexibility is not lost in using any proportion of of hydrogen chloride, said process including steps hydrogen chloride and chlorine as the source of operated in tandem: chlorine values. Particularly in the case of the man- first, subjecting chlorinated ethylene consisting ufacture of vinyl chloride, which requires about 0.45 55 essentially of perchloroethylene to oxychlorination pounds of ethylene per pound of product, any with hydrogen chloride and oxygen in the presence savings in the cost of hydrocarbon raw material of an oxychlorination catalyst to give reaction pro- would be important. ducts consisting essentially of hexachloroethane

2 3 EP 0 453 502 B1 4 and water; loroethane, supplemental chlorine can be added to second, isolating said hexachloroethane from the second reaction step. Thus, any proportion of the reaction products of the first step and reacting hydrogen chloride and chlorine can be used in the it with ethane feedstock in the vapor phase to overall process. In a preferred embodiment, par- produce chlorinated ethanes, chlorinated ethylenes 5 tially chlorinated ethane or ethylene produced in including perchloroethylene, and hydrogen chlo- step 2 is recycled to step 2 for further chlorination. ride; A preferred ethane feed stock to step 2 comprises and third, isolating perchloroethylene and hy- a chlorinated ethane or mixture of chlorinated drogen chloride from hydrocarbon products of the ethanes. second step and recycling the hydrogen chloride 10 The mechanism by which ethane is chlorinated and perchloroethylene thus isolated to the first step in the second reaction step is complex, but certain whereby chlorination is accomplished forming re- rules are helpful in clarifying the chemistry. In generated hexachloroethane, the process is op- actuality, both chlorination and dehydrochlorination erated with total utilization of hydrogen chloride, occur together. Thus, the invention contemplates and net production of hydrogen chloride is avoided. 15 that ethane forms dichloroethane by substitution The reactions of the proposed process are chlorination and this compound in turn is de- illustrated by the following equations for the prep- hydrochlorinated to give vinyl chloride. The inter- aration of vinyl chloride. mediate product ethyl chloride, because of its relative thermal stability, does not disassociate appre- 1. CCI2=CCI2 + 2HCI + 1/202 - CCI3CCI3 + 20 ciably to give ethylene. H20 At the elevated temperature at which the second reaction step is conducted, addition chlorina- 2a. 2CCI3CCI3 + C2HG - 2CCI2=CCI2 + tion across a double bond is negligible. Further- C2H3CI + 3HCI more, substitution chlorination of unsaturated com- 25 pounds is known to be slower than that for satu- By balancing the above equations, one obtains rated compounds. Therefore, according to the in- the net reaction as follows: vention, ethane and ethyl chloride are preferentially chlorinated instead of vinyl chloride, and the latter, 3. C2HG + HCI + 02 - C2H3CI + 2H20 once formed, is relatively stable. 30 In a preferred embodiment, by modifying the In one preferred embodiment in which chlorine conditions under which the second reaction step is is added to the second reaction step, the following carried out, the proportion of products may be reaction occurs: adjusted. Thus, preferably, by using a large excess of ethane, by recycling ethyl chloride to the reac- 2b. 2CI2 + C2HG - C2H3CI + 3HCI 35 tor, and by preventing the back-mixing of vinyl chloride in the reactor, the output of vinyl chloride The first reaction step in which perch- can be maximized. If, on the other hand, the more loroethylene is oxychlorinated to hexachloroethane highly chlorinated products, such as trich- may typically be carried out in a molten salt reac- loroethylene, are desired, more severe conditions tor, fluidized bed reactor, or in a shell and tube 40 can be used. Under the latter conditions, a higher reaction in order to obtain efficient heat removal. proportion of hexachloroethane is supplied to the The temperature is maintained within the range of reactor, and higher vapor phase temperatures in 200° to 375° C. The catalyst of choice is copper the above range are preferred. chloride deposited on an inert support. This is the The temperature control of the second reaction well-known Deacon catalyst, which has been used 45 step is facilitated by the simultaneous chlorination in experimental processes to produce chlorine from and dehydrochlorination reactions. This advantage hydrogen chloride and air. In a preferred embodi- was pointed out in U.S. Patent No. 2,547,139. Sub- ment, any of various salts may be admixed with the stitution chlorination, e.g., the formation of ethyl copper chloride catalyst to promote its effective- chloride from ethane, is exothermic or heat produc- ness, e.g., potassium chloride, ferric chloride, and 50 ing. Dehydrochlorination such as occurs in the for- lead chloride. mation of vinyl chloride from dichloroethane is en- The second reaction step is conducted in the dothermic or heat absorbing. By conducting the vapor phase at elevated temperatures, e.g., in the chlorination and dehydrochlorination reactions in an range from 400 0 to 700 0 C. The required tempera- intimate manner, the heat requirements can be ture is related to the reaction time; for example, a 55 more nearly balanced. shorter retention time can be used at higher temperatures. Should insufficient hydrogen chloride be available to produce the required hexach-

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Detailed Description of the Preferred Embodiment and to avoid pollution problems caused by the release of hydrocarbons in the vent gases. The FIGURE is a schematic view of the opera- 3. Perchloroethylene that is reformed in the ther- tion of a preferred embodiment of the process of mal reactor must be isolated from the product the invention. Air, hydrogen chloride and perch- 5 stream before being recycled to the oxychlorina- loroethylene are fed to the shell and tube reactor tion reactor. Any saturated hydrocarbons which 10 which contains the copper chloride catalyst. The are fed to the oxychlorination reactor will be oxychlorination reaction is carried out in the reactor subject to burning. Unsaturated hydrocarbons, 10, and the effluent is cooled in a condensor 20 to other than perchloroethylene, will be chlorinated condense the liquids. The inert gases are vented io in the oxychlorination reactor and eventually while the water is decanted from the chlorinated lead to unwanted byproducts. Any volatile impu- organics in a separator 30. Hexachloroethane, in- rities will escape in the vent gases. cluding hexachloroethane dissolved in any unreac- The necessary separations of the recycle ted perchloroethylene, is pumped to the thermal streams cannot be taken for granted. For example, reactor 40 where in the vapor phase reaction which is hexachloroethane is very slightly miscible in water ensues with ethane feedstock, it serves to chlo- and thus presents a challenge in drying it com- rinate the ethane. pletely. The principles of azeotropic distillation are The hot vapors from the thermal reactor 40 are used to separate hydrogen chloride. And finally, in preferably quenched (for example, with a stream of isolating perchloroethylene from the product stream cold perchloroethylene) to minimize the formation 20 the differences in boiling points determine its ease of heavy ends and tars. Unreacted ethane and of fractionation. hydrogen chloride are separated from the chlorinat- The products produced by the present inven- ed organics which as products are pumped to a tion are valuable items of commerce. Vinyl chloride distillation column 50 for fractionation. In an ab- monomer is consumed in huge quantities in the sorber 60, hydrogen chloride is separated from the 25 manufacture of plastic materials. Vinylidene chlo- unreacted ethane by absorption in weak hydrochlo- ride is another valuable monomer which is used to ric acid and fed to a stripper 70. In a preferred produce specialty films known commonly by the embodiment, the stripped hydrogen chloride is re- Saran tradename. Trichloroethylene is an effective cycled to the catalytic reactor 10. The perch- degreasing solvent employed by the aircraft, auto- loroethylene still bottoms are returned also to the 30 motive, and other metal fabricating industries. Be- catalytic reactor for the oxychlorination step. After cause of its relative safety and flame retardency, further fractionation in another column (not shown), perchloroethylene is a popular dry cleaning solvent ethyl chloride and, if desired, other light ends may for woolen garments and other clothes. be recycled with the unreacted ethane to the thermal reactor 40. The principal products obtained by 35 Claims distillation are ethyl chloride, vinyl chloride, vinylidene chloride, trichloroethylene and perch- 1. A process for the chlorination of ethane using loroethylene. hydrogen chloride as the source of chlorine Although the process as described seems rath- and avoiding net production of hydrogen chlo- er straightforward, successful operation depends on 40 ride, said process including steps operated in the strict adherence to the following rules: tandem: 1. Hexachloroethane produced via oxychlorina- first, subjecting chlorinated ethylene con- tion must be isolated from the reaction products sisting essentially of perchloroethylene to ox- before being fed to the thermal reactor. Any ychlorination with hydrogen chloride and oxy- impurities, with the exception of perch- 45 gen in the presence of an oxychlorination cata- loroethylene, must be separated from the hex- lyst to give reaction products consisting essen- achloroethane in order to avoid the formation of tially of hexachloroethane and water; byproducts, which are difficult to separate and second, isolating said hexachloroethane which reduce the hydrogen chloride efficiency. from the reaction products of the first step and The thermal reactor must be kept under anhy- 50 reacting it with ethane feedstock in the vapor drous conditions or above the dew point to phase to produce chlorinated ethanes, prevent severe corrosion problems. All oxygen chlorinated ethylenes including perch- has to be excluded from the thermal reactor to loroethylene, and hydrogen chloride; avoid burning and to prevent the formation of and third, isolating perchloroethylene and water. 55 hydrogen chloride from hydrocarbon products 2. Hydrogen chloride, before being recycled to of the second step and recycling the hydrogen the oxychlorination reactor, must be freed of all chloride and perchloroethylene thus isolated to hydrocarbons to prevent combustion reactions the first step whereby chlorination is accom-

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plished forming regenerated hexachloroethane, schlieBlich von Perchlorathylen, und Chlorwas- the process is operated with total utilization of serstoff zu erzeugen; hydrogen chloride, and net production of hy- und drittens des Isolierens von Perchlor- drogen chloride is avoided. athylen und Chlorwasserstoff aus Kohlenwas- 5 serstoffprodukten des zweiten Schrittes und 2. A process according to claim 1 in which ele- Fuhren des so isolierten Chlorwasserstoffes mental chlorine is added to step 2. und Perchlorathylens im Kreislauf zum ersten Schritt, wodurch die Chlorierung unter Bildung 3. A process according to claim 1 in which par- von regeneriertem Hexachlorathan bewerkstel- tially chlorinated ethane/ethylene produced in io ligt wird, wobei das Verfahren mit vollstandiger step 2 is recycled to step 2 for further chlorina- Verwendung des Chlorwasserstoffes betrieben tion. und eine Nettoproduktion von Chlorwasserstoff vermieden wird. 4. A process according to claim 1 in which the ethane feedstock to step 2 comprises a is 2. Verfahren nach Anspruch 1 , bei dem im Schrit- chlorinated ethane or a mixture of chlorinated te 2 elementares Chlor zugefugt wird. ethanes. 3. Verfahren nach Anspruch 1 , bei dem im Schrit- 5. A process according to claim 1 in which the te 2 erzeugtes teilweise chloriertes At- catalyst used in step 1 comprises copper chlo- 20 han/Athylen in den Schritt 2 fur eine weitere ride on an inert support. Chlorierung ruchgefuhrt wird.

6. A process according to claim 5 where the 4. Verfahren nach Anspruch 1, bei dem das At- catalyst comprises an admixture of copper han-Ausgangsmaterial zu Schritt 2 ein chlorier- chloride with salt selected from the group con- 25 tes Athan oder eine Mischung chlorierter Atha- sisting of potassium chloride, ferric chloride, ne umfaBt. and lead chloride. 5. Verfahren nach Anspruch 1, bei dem der im 7. A process according to claim 1 in which the Schritte 1 benutzte Katalysator Kupferchlorid oxychlorination reaction in step 1 is carried out 30 auf einem inerten Trager aufweist. at temperatures in the range of 200 ° to 375 ° C. 6. Verfahren nach Anspruch 5, bei dem der Kata- lysator eine Mischung von Kupferchlorid und 8. A process according to claim 1 in which the einem aus der aus Kaliumchlorid, Ferrichlorid vapor phase ethane chlorination reaction is 35 und Bleichlorid bestehenden Gruppe ausge- carried out at temperatures in the range from wahltem Salze umfaBt. 400 ° to 700 ° C. 7. Verfahren nach Anspruch 1, bei dem die Ox- Patentanspruche ychlorierungsreaktion im Schritte 1 bei Tempe- 40 raturen im Bereiche von 200° bis 375 °C 1. Verfahren zur Chlorierung von Athan unter Ver- durchgefuhrt wird. wendung von Chlorwasserstoff als Quelle fur Chlor und unter Vermeidung einer Nettopro- 8. Verfahren nach Anspruch 1 , bei dem die Chlo- duktion von Chlorwasserstoff, welches Verfah- rierungsreaktion von Athan in der Dampfphase ren die nacheinander betriebenen Verfahrens- 45 bei Temperaturen im Bereiche von 400° bis schritte umfaBt: 700 ° C durchgefuhrt wird. erstens des Unterwerfens von im wesentli- chen aus Perchlorathylen bestehendem chlo- Revendicatlons rierten Athylen unter eine Oxychlorierung mit Chlorwasserstoff und Sauerstoff in Gegenwart 50 1. Procede pour la chloration d'ethane utilisant de eines Oxychlorierungs-Katalysators, urn im we- I'acide chlorhydrique comme source de chlore sentlichen aus Hexachlorathan und Wasser be- et evitant la production nette d'acide chlorhy- stehende Reaktionsprodukte zu ergeben; drique, ledit procede comprenant les etapes, zweitens des Isolierens des Hexachlorat- effectuees en tandem, consistant a : hans aus den Reaktionsprodukten des ersten 55 premierement, faire subir a de I'ethylene Schrittes und seines Umsetzens mit einem At- chlore constitue essentiellement de perchloroe- han-Ausgangsmaterial in der Dampfphase, urn thylene, une oxychloration avec de I'acide chlorierte Athane bzw. chlorierte Athylene, ein- chlorhydrique et de I'oxygene en presence

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d'un catalyseur d'oxychloration pour obtenir des produits de reaction constitues essentiellement d'hexachloroethane et d'eau; deuxiemement, isoler ledit hexachloroethane des produits de reaction de la premiere 5 etape et le faire reagir avec une charge d'ethane en phase vapeur pour produire des ethanes chlores, des ethylenes chlores comprenant du perchloroethylene, et de I'acide chlorhydrique; et troisiemement, isoler le perchloroethyle- 10 ne et I'acide chlorhydrique des produits hydro- carbones de la seconde etape et recycler I'acide chlorhydrique et le perchloroethylene ainsi isoles a la premiere etape de maniere a effec- tuer la chloration en formant de I'hexachloroe- is thane regenere, en realisant le procede en utilisant totalement I'acide chlorhydrique, et en evitant la production nette d'acide chlorhydrique. 20 2. Procede selon la revendication 1, dans lequel on ajoute du chlore elementaire dans I'etape 2.

3. Procede selon la revendication 1, dans lequel on recycle I'ethane/ethylene partiellement chlo- 25 re produit dans I'etape 2 a I'etape 2 pour une chloration supplemental.

4. Procede selon la revendication 1, dans lequel la charge d'ethane introduite dans I'etape 2 30 comprend un ethane chlore ou un melange d'ethanes chlores.

5. Procede selon la revendication 1, dans lequel le catalyseur utilise dans I'etape 1 comprend 35 du chlorure de cuivre sur un support inerte.

6. Procede selon la revendication 5, dans lequel le catalyseur comprend un melange de chlorure de cuivre avec un sel choisi dans le groupe 40 constitue du chlorure de potassium, du chlorure ferrique et du chlorure de plomb.

7. Procede selon la revendication 1, dans lequel on effectue la reaction d'oxychloration dans 45 I'etape 1 a des temperatures variant entre 200 ° et 375 ° C.

8. Procede selon la revendication 1, dans lequel on effectue la reaction de chloration de I'etha- 50 ne en phase vapeur a des temperatures variant entre 400 0 et 700 0 C.

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