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 © EUROPEAN PATENT SPECIFICATION © Date of publication of patent specification: 15.02.95 © Int. CI.6: C07C 21/06, C07C 21/08, C07C 21/10, C07C 21/12 © Application number: 90902585.0 @ Date of filing: 27.11.89 © International application number: PCT/US89/05321 © International publication number: WO 90/08116 (26.07.90 90/17) 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) © Publication of the grant of the patent: @ Inventor: Stauffer, John E. 15.02.95 Bulletin 95/07 6 Pecksland Road Greenwich © Designated Contracting States: Connecticut 06830 (US) BE DE ES FR GB IT NL © 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) 00 CM o m oo 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 hydrocar- bons. 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 rela- tive 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 sec- ond 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.