Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
  • H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
  • H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
  • H01B3/22—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils hydrocarbons

Definitions

• This invention relates to a liquid dielectric composition obtained from the alkylation product of benzene with ethylene.
• Belgian Patent A-504293 discloses that an oil for use as electrical insulation for cables can be obtained from the product of alkylation of aromatic hydrocarbons by heating the alkylation product which has a molecular weight above 500, for example with an absorbent such as a decolourising earth, silica gel or alumina.
• the present invention provides a liquid dielectric composition obtained as a result of a process which comprises reacting benzene with ethylene in the presence of an alkylation catalyst to obtain an alkylation product containing unreacted benzene, ethylbenzene, polyethylbenzenes, 1,1-diphenylethane and higher molecular weight products, characterised in that benzene, ethylbenzene and polyethylbenzenes are removed from said alkylation product and thereafter there is recovered by distillation from the residual alkylation product a fraction containing 1,1-diphenylethane and whose boiling point is in the temperature range of 255°C to 420°C as said liquid dielectric composition.
• the boiling point of the recovered fraction is more preferably 260°C to 400°C and most preferably 268°C to 400°C.
• the process employed in obtaining the new liquid dielectric compositions defined and claimed herein comprises reacting benzene with ethylene in the presence of an alkylation catalyst to obtain an alkylation product containing largely unreacted benzene, ethylbenzene, 1,1-diphenyiethane, polyethylbenzenes and still higher molecular weight products, separating benzene, ethylbenzene and polyethylbenzenes from said alkylation product and thereafter recovering from the remainder a fraction which contains 1,1-diphenylethane and whose boiling point is in the temperature range of 255°C to 420°C, preferably 260°C to 400°C, most preferably 268°C to 400°C, as said liquid dielectric composition.
• the alkylation of benzene with ethylene that can be employed to obtain the new liquid dielectric compositions claimed herein can be any of the processes known in the art for producing a product containing ethylbenzene, for example, either liquid phase alkylation or vapor phase alkylation.
• the molar ratios of benzene to ethylene employed can be, for example, in the range of about 25:1 to about 2:1, preferably about 10:1 to about 3:1.
• an alkylation catalyst for example, a Friedel Crafts catalyst, such as aluminum chloride or aluminum bromide or some other organo-aluminum halide; Lewis acids, such as promoted ZnCl 2 , FecI 3 and BF 3 ; and Bronsted acids, including sulfuric acid, sulfonic acid and p-toluene sulfonic acid, hydrofluoric acid, etc., in an amount corresponding to about 0.002 to about 0.050 parts, preferably about 0.005 to about 0.030 parts, relative to ethylbenzene produced, are reacted in a temperature range of about 20° to about 175°C., preferably about 90° to about 150°C., and a pressure in the range of about atmospheric to about 250 pounds per square inch gauge (about atmospheric to about 17.6 kilograms per square centimeter that is 170 x 10 4 Pa), preferably about seven to about 200 pounds per square inch
• a Friedel Crafts catalyst such as aluminum chloride or aluminum bromide
• the reactants can be passed over a suitable alkylation catalyst bed containing alkylation catalysts, such as phosphoric acid on kieselguhr, silica or alumina, aluminum silicates, etc. at a convenient hourly space velocity in a temperature range of about 250° to about 450°C., preferably about 300° to about 400°C., and a pressure of about 400 to about 1200 pounds per square inch gauge (about 28 to about 85 kilograms per square centimeter that is, about 265 x 10 4 Pa to about 830 x 10 4 Pa), preferably about 600 to about 1000 per square inch gauge (about 42 to about 70 kilograms per square centimeter that is, about 410 x 10 4 Pa to about 690 x 10 4 Pa).
• alkylation catalysts such as phosphoric acid on kieselguhr, silica or alumina, aluminum silicates, etc.
• an alkylation product is obtained containing unreacted benzene, the desired ethylbenzene, polyethylbenzenes, such as diethylbenzenes and triethylbenzene, and higher-boiling products.
• the alkylation product can be treated in any conventional manner to remove any alkylation catalyst present therein.
• the alkylation product can be sent to a settler wherein the aluminum chloride complex is removed and recycled to the reaction zone and the remaining product can then be water washed and neutralized.
• the resulting alkylation product is then distilled at atmospheric pressure or under vacuum to recover unreacted benzene (B.P. 80°C), ethylbenzene (B.P. 136°C.) and polyethylbenzenes (B.P. 176°-250°C).
• the heavier product remaining after removal of benzene, ethylbenzene and polyethylbenzenes, as described above, is a dark, viscous, high-boiling material from which the novel liquid dielectric compositions defined and claimed herein are obtained.
• the said heavier product is simply subjected to distillation and the entire fraction recovered whose boiling point at atmospheric pressure (14.7 pounds per square inch or 760 millimeters of mercury that is 10.13 x 10 4 Pa is in the temperature range of about 255° to about 420°C., or preferably the fraction recovered whose boiling point is in the temperature range of about 260° to about 400°C., most preferably about 268° to about 400°C., constitutes the desired and novel liquid dielectric composition. That portion whose boiling point is in the range of about 255° to about 420°C. will contain a maximum of about 20 weight per cent 1,1-diphenylethane, that portion whose boiling point is in the range of about 260° to about 400°C.
• a number of liquid dielectric compositions were prepared from the residue, or heavier products, obtained as a result of the production of ethylbenzene.
• This residue was obtained as follows. Benzene and ethylene in a molar ratio of 9:1 were contacted in the liquid phase, while stirring, in a reactor at a temperature of 130°C. and a pressure of 70 pounds per square inch gauge (4.9 kilograms per square centimeter that is 48 x 10 4 Pa) in the presence of AIC1 3 catalyst over a period of one hour, which was sufficient to convert all of the ethylene.
• the AIcI 3 complex catalyst was prepared by dissolving AIcI 3 in a polyethylbenzene cut from a previous run so that after the addition the composition of the catalyst complex was as follows: 31.5 weight per cent AICI 3 , 7.0 weight per cent benzene, 19.3 weight per cent ethylbenzene, 29.8 weight per cent polyalkylated benzenes, 3.4 weight per cent 1,1-diphenylethane and 9.0 weight per cent higher boiling components.
• the amount of AIcI 3 present in the catalyst mixture amounted to 0.0034 parts by weight per one part by weight of ethylbenzene produced.
• ethyl chloride promoter in an amount corresponding to 0.0034 parts by weight per one part by weight of ethylbenzene produced to maintain a high catalyst efficiency.
• Analysis of the alkylation product showed the presence of 49.0 weight per cent benzene, 32.9 weight per cent ethylbenzene, 17.5 weight per cent of polyalkylated benzenes (6.0 weight per cent diethylbenzene, 2.7 weight per cent tri- ethylbenzenes, 2.1 weight per cent tetra- ethylbenzenes and 6.7 weight per cent other alkylbenzenes), 0.1 weight per cent 1,1-diphenylethane and 0.4 weight per cent residue.
• the alkylation product was subjected to distillation to recover unreacted benzene, ethyl- benzene and polyalkylated benzenes, and the benzene and polyalkylated benzenes were recycled to the reaction zone.
• the residue remaining was a dark, viscous, high-boiling material, and was produced in an amount corresponding to 0.014 parts for each part of ethylbenzene produced.
• aged aluminum chloride complex the amount of high-boiling residue formed can be increased substantially.
• compositions can be further treated, if desired, for example, to further improve their properties for a particular purpose, for example, to improve their flash point, interfacial tension, pour point, viscosity, oxidation stability, corrosion resistance, etc.
• the power factor of the composition claimed herein can be further improved by recovering said composition from the heavier products defined herein by distillation in the presence of basic materials, such as Group I and Group II alkali metals and alkaline earth metals, their oxides and hydroxides, as defined in our copending European Patent Application No. 78300088.8 (publication number 0000621).

Landscapes

• Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Organic Insulating Materials (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 1977
  • 1977-07-21 US US05/817,693 patent/US4111824A/en not_active Expired - Lifetime
• 1978
  • 1978-06-06 CA CA304,857A patent/CA1084693A/en not_active Expired
  • 1978-06-27 DE DE7878300089T patent/DE2860389D1/de not_active Expired
  • 1978-06-27 EP EP78300089A patent/EP0000622B1/en not_active Expired
  • 1978-07-20 IT IT25916/78A patent/IT1099582B/it active
  • 1978-07-20 JP JP8779178A patent/JPS5423086A/ja active Granted

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