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Purification of Ethylene Dichloride

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Purification of Ethylene Dichloride Patentamt àJEuropâisches European Patent Office (jj) Publication number: 0 007 064 Office européen des brevets Bl @ EUROPEAN PATENT SPECIFICATION @ Dateof publication of patent spécification: 19.01.83 @ Int. Cl.3: C 07 C 17/38, C 07 C 1 9/045 @ Application number: 79102263.5 @ Date offiling: 04.07.79 (54) Purification of ethylene dichloride. (30) Priority: 07.07.78 US 922717 @ Proprietor: PPG INDUSTRIES, INC. One Gateway Center Pittsburgh Pennsylvania 1 5222 (US) (43) Date of publication of application: 23.01.80 Bulletin 80/2 @ Inventor: Walker, Henry Rideout 922 Wilshire (45) Publication of the grant of the patent: Corpus Christi, Texas 7841 1 (US) 19.01.83 Bulletin 83/3 (74) Representative: Hann, Michael, Dr. (84) Designated Contracting States: Marburger Strasse 38 BE DE FR GB IT NL SE D-6300 Giessen (DE) (56) References cited: DE - B - 1 468 480 DE-B - 1 793 051 DE - B - 2 603 477 US -A- 3 691 239 US -A- 3 996 300 US-A-4020117 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 shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1 ) European patent convention). Courier Press, Leamington Spa, England. Background of the invention of said product is reduced by contacting it with Ethylene dichloride (1,2-dichloroethane) is alumina, said process being characterized in typically produced by catalytic vapor phase oxy- that the chloral containing reaction product is chlorination of ethylene wherein a gaseous contacted with alumina by passing a gaseous mixture of ethylene, hydrogen chloride, and stream of said reaction product through a fixed oxygen are reacted in the presence of a Deacon- bed of alumina at a temperature of from 200°C type catalyst, e.g., copper halide catalyst. The to 300°C, said alumina having a Brunauer, oxychlorination product gas stream is Emmet and Teller surface area of from 30 to condensed to form organic and aqueous acidic 600 square meters per gram, the volume of said liquid phases. The organic phase containing alumina bed being from 10 to 60 percent of the crude ethylene dichloride is further purified by, volume of the oxychlorination catalyst, con- for example, distillation and the aqueous acidic densing said stream and recovering ethylene di- phase is discharged to waste. chloride from te condensation product. Although satisfactorily high yields of ethylene The determination of the Brunauer, Emmet dichloride may be obtained by the vapor phase and Teller ("BET") surface is described in J. Am. oxychlorination of ethylene, both the organic Chem. Soc. Vol. 60, pp. 30 et seq. (1938). A and aqueous phases typically contain preferred range of the BET surface area of objectionable amounts of chloral, i.e., from alumina is from 100 to 300 square meters per about 0.2 to 0.5 percent by weight, in the gram. The volume of the alumina is preferably organic phase and in excess of 2 percent by from 10 percent to 30 percent of the volume of weight in the aqueous phase. the oxychlorination catalyst. Since chloral is classified as a pollutant, it A higher relative volume of alumina to oxy- must be substantially removed from the chlorination catalyst is used when the alumina aqueous phase prior to discharge to waste and has a low BET surface area and conversely a also must be removed from the organic phase in lower relative volume of alumina to oxy- order to produce high purity ethylene dichloride. chlorination catalyst is used when the alumina One means of removing chloral from the has a high BET surface area. condensed oxychlorinated product stream is Care should be taken that neither too much disclosed in U.S. Patent No. 3,378,597 wherein nor too little alumina be used. The use of too aqueous sodium hydroxide is used to much alumina will result in an overly long decompose chloral to chloroform and sodium contact time with the oxychlorination product formate. However, both chloroform and sodium stream which tends to decompose not only formate also pose a waste disposal problem and chloral but also ethylene dichloride product. require additional treatment, e.g., bioxidation or Conversely with the use of too little alumina the like, before being discharged to a receiving there will be insufficient contact time with the stream. oxychlorination product stream resulting in DE-B2-1 793 051 shows a process for incomplete decomposition of chloral. recovering the reaction mixtures obtained in the The optimum volume ratio of alumina having preparation of ethylene dichloride by vapor a particular BET surface area to oxychlorination phase oxychlorination of ethylene. The reaction catalyst for a given system may, however, be product is first condensed to separate ethylene readily determined without excessive experi- dichloride and water in the liquid phase. The mentation simply by varying the volume of remaining gas stream which comprises alumina to oxychlorination catalyst within the excessive ethylene is reacted with chlorine in above specified limits bearing in mind that the the presence of alumina in order to form higher the BET surface area of the alumina, the ethylene dichloride. In this process chloral is not lower the relative volume of alumina based on removed from the major part of the reaction the volume of oxychlorination catalyst. product which is condensed immediately after The temperature of the alumina bed is main- the oxychlorination. tained at from 200°C to 300°C, preferably from It is desirable, therefore, to provide means for 240°C to 260°C, and, in order to obtain satis- removing chloral prior to condensing the factory decomposition of chloral, the oxy- gaseous oxychlorination product stream which chlorination product stream should contain from would preclude further treatment of any phase 1 to 5 percent by volume oxygen. to remove chloral therefrom. In a typical practice of the invention, In accordance with this invention a process ethylene, hydrogen chloride, and oxygen gases has been found of preparing ethylene dichloride are fed in known fashion to a fluid reactor con- by vapor phase oxychlorination of ethylene taining an oxychlorination catalyst at a rate suf- wherein a gaseous mixture of ethylene, ficient to maintain the catalyst bed in a fluidized hydrogen chloride, and oxygen are contacted at condition without significant entrainment of an elevated temperature with an .oxy- catalyst particles in the product gas stream and chlorination catalyst to produce a chloral con- to intimately contact the gaseous reactants with taining reaction product and the chloral content the fluidized catalyst. Of course, the vapor phase oxychlorination of ethylene to ethylene di- weight percent potassium, and 9.0 weight chloride may be conducted using a fixed or percent chloride; had a BET surface area of static catalyst bed rather than a fluidized about 37 square meters per gram; and had a catalyst. Particle size of the oxychlorination bulk density of about 39.4 pounds per cubic catalyst is not particularly critical, although for foot. fluid bed operation catalyst particle size is typically in the range of 0.076 to 0.500 mm, preferably between 0.152 to 0.388 mm. The Example 2 reaction may be conducted over a wide range of A tube from a corrosion resistant alloy (79 temperature, for example, between 150°C to percent Ni, 14 percent Cr, 7 percent Fe) 1,5 m 500°C, preferably between 250°C and 350°C. in height and 5 cms in diameter was employed Contact time between the gaseous reactants is as a fluid bed oxychlorination reactor. The typically not more than about 30 seconds and reactor was enclosed in a 6 inch diameter steel usually about 10 seconds. Depending on jacket forming an annular heat exchange reaction conditions and catalyst selection, system. "Dow Therm E" (a diphenyl-diphenyl- conversion of ethylene to ethylene dichloride oxide eutectic sold by The Dow Chemical Co.) usually ranges from about 70 percent to sub- was circulated in the annular space formed stantially quantitative and ethylene dichloride between the jacket and the outer surface of the crude having an ethylene dichloride content of reactor to control the fluid bed temperature. from 97 percent to 99 percent may be obtained. A 1 liter capacity glass secondary reactor The product gas stream from the oxy- was connected to the oxychlorination reactor chlorination reactor is passed through a vent with a glass-crossover. Both the secondary secondary reactor containing a fixed or static reactor and the crossover were wrapped with bed of particulate alumina maintained at a tem- insulation and externally controlled heating perature of from 200°C to 300°C, the volume tape. The outlet of the secondary reactor was of alumina being proportioned to the volume of connected to a condenser system. oxychlorination catalyst in the fluid reactor as The oxychlorination reactor was charged to a described hereinabove. depth of 63.5 cms with the catalyst prepared in It is, of course, to be understood that rather Example 1 and the secondary reactor was than employing a single alumina containing charged with alumina. Two types of commer- reactor, two or more such reactors connected in cially available alumina were tested, i.e., series may be employed. Aluminum Company of America F-1 grade The gaseous stream, after passage through alumina screened to 0.388 mm (+40 mesh) the alumina bed, is condensed in known fashion having a BET surface area of 300 ml/g (Type A) to form organic and aqueous liquid phases. The and Norton Co.
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