JPH0378723B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing electrical insulating oil consisting of a dehydrogenated product. Alkylation, in which an alkylated aromatic hydrocarbon is obtained by reacting an alkylating agent with an aromatic hydrocarbon in the presence of an alkylation catalyst, is widely used industrially. For example, ethylbenzene is produced industrially by alkylating ethylene with benzene using a Friedel-Crafts catalyst such as aluminum chloride. The ethylbenzene thus obtained is then dehydrogenated to produce styrene. However, in such alkylation, in addition to the desired alkylated aromatic hydrocarbon, diarylalkane and heavy products are produced as by-products. Conventionally, there has been no effective use of such by-products. On the other hand, various improvements are being made to oil-impregnated electrical equipment, such as oil-impregnated capacitors and oil-impregnated cables, in order to meet the demands for higher voltage and smaller size. That is, insulating paper has traditionally been used as an insulator (dielectric) in these oil-impregnated electrical devices, but it is now being replaced partially or completely by polyolefin such as polypropylene or plastic film such as polyester. In addition, in response to the above-mentioned deformation of the constituent materials of oil-impregnated electrical equipment, there is a need to improve electrical insulating oil for impregnation. Therefore, the present inventors discovered that by dehydrogenating the above-mentioned alkylation by-product, an excellent electrical insulating oil for oil-impregnated electrical equipment, which has been developed in recent years, could be obtained. It has been completed. That is, this invention reacts an alkylating agent with a monocyclic aromatic hydrocarbon in the presence of an alkylation catalyst, and mainly produces unreacted products, mono- and poly-alkylated monocyclic aromatic hydrocarbons, diaryl alkanes, and heavy products. and then separating unreacted products, mono- and polyalkylated monocyclic aromatic hydrocarbons from this alkylated product,
The present invention relates to a method for producing electrical insulating oil, characterized in that a fraction obtained by removal is dehydrogenated before or after a refining treatment, which is performed as necessary. In the above step, in addition to the alkylated monocyclic aromatic hydrocarbon, an alkylated product is obtained which contains diaryl alkanes and heavy products, and the diaryl alkanes and heavy products thus obtained are Any alkylation may be used as long as it is a compound that can be converted into olefins such as monoolefin or diolefin by dehydrogenation. Accordingly, such aromatic hydrocarbons include monocyclic aromatic hydrocarbons, namely benzene and alkylbenzenes such as toluene and xylene. In addition, alkylating agents include olefins such as ethylene, propylene, butene, ethanol,
Examples include alkanols such as propanol and butanol, and halogenated paraffins such as chlorinated ethane. In the present invention, the aromatic hydrocarbon and the alkylating agent may be appropriately selected according to the above conditions. Known alkylation catalysts can be used, such as Friedel-Crafts catalysts such as aluminum chloride, mineral acids such as sulfuric acid, organic acids such as P-toluenesulfonic acid, and trifluoromethanesulfonic acids. These include super strong acids and solid acids such as silica, alumina, and zeolite. After alkylation, unreacted substances such as benzene, mono- and polyalkylated monocyclic aromatic hydrocarbons are separated from the alkylated product, and further dehydrogenation is performed. Dehydrogenation is performed using a known dehydrogenation catalyst,
The reaction may be carried out under reaction conditions such that side reactions such as decomposition and polymerization do not occur and olefins such as monoolefins and diolefins are produced. After dehydrogenation, light components and the like are distilled off to obtain the dehydrogenated product of the present invention. In the present invention, a particularly suitable alkylation is polystyrene because it is carried out on an industrial scale and by-products can be obtained at low cost and in large quantities, and its dehydrogenated product is excellent as an electrical insulating oil. Alternatively, to obtain polyvinyltoluene, benzene or toluene is reacted with ethylene in the presence of an alkylation catalyst, mainly unreacted benzene,
The alkylation yields alkylated products containing ethylbenzene, polyethylbenzene, 1,1-diphenylethane as diarylalkane, and heavy substances. Therefore, the present invention will be further explained below by taking this alkylation as an example. Alkylation of benzene and ethylene can be carried out by known methods, for example liquid phase alkylation or gas phase alkylation. The molar ratio of benzene to ethylene is, for example, about 25:
1 to about 2:1, preferably about 10:1 to about 3:1
is within the range of As the alkylation catalyst, solid acid catalysts, mineral acids, so-called Friedel-Crafts catalysts, etc. are preferably used. For example, alumina, silica/alumina, zeolite, sulfuric acid, hydrofluoric acid, phosphoric acid, sulfonic acid, P-toluenesulfonic acid, aluminum halides such as aluminum chloride, aluminum bromide, zinc chloride, iron chloride, boron fluoride. and so on. In the liquid phase reaction, the reaction temperature range is about 20 to about 175°C, preferably about 90 to 150°C, and the pressure is sufficient to maintain the liquid state, for example, about 0.5 to about 14
Kg/ ^cm2 . The reaction time is usually about 10 minutes to about 10 hours, preferably about 20 minutes to about 3 hours. In gas phase reactions, alkylation catalysts such as diatomaceous earth, silica, alumina, and aluminum silicate are treated with phosphoric acid, and solid acid catalysts such as alumina supported on silica gel are used, and the reaction temperature is approximately
250 to about 450°C, preferably about 300 to about 400°C, reaction pressure about 25 to about 85 Kg/cm ³ , preferably about 42 to about 70
The reaction can be carried out at Kg/cm ³ . Industrial methods for producing ethylbenzene by reacting ethylene with benzene include the aluminum chloride method using aluminum chloride as a catalyst, the high-pressure method using an alumina catalyst supported on silica gel developed by Cotpers, and the diatomaceous earth method developed by UOP. Solid phosphoric acid method using a solid catalyst impregnated with phosphoric acid, also
Alkar developed by UOP using boron fluoride or its complex as a catalyst
method, and a method using a zeolite catalyst developed by Mobil Corporation are known. By reacting as described above, unreacted substances such as benzene and ethylene, mono- and polyethylbenzene, 1,1-diphenylethane, 1-
Phenyl-1-ethyl phenylethane, 1,1-
Alkylation products are obtained, including di(ethylphenyl)ethane and heavy products. The alkylation catalyst, such as an aluminum chloride catalyst, can be removed from the alkylated product by conventional methods such as precipitation and filtration, followed by washing with water and neutralization. Unreacted benzene, ethylbenzene and polyethylbenzene are then removed from the alkylation product.
Separate by conventional methods such as distillation. The alkylated product separated in this way contains alkylated substances that are solid at room temperature and can only be used as fuel. The inventive fraction to be treated is obtained. This fraction of the present invention has a boiling point of approximately 255 to 420 in the alkylation of ethylene and benzene.
°C, preferably about 260-400 °C, more preferably about
A fraction in the range of 268 to 400°C, and the fraction in this boiling range contains 1,1-dipheniethane, 1-phenyl-1-ethylphenylethane, 1,1-di(ethylphenyl)ethane and heavy products. contains things. Purification treatments such as neutralization to remove alkylation catalyst residues can be performed before or after the subsequent dehydrogenation treatment. This purification can be carried out using a suitable inorganic or organic basic substance.
For example, alkali metals in group 1 of the periodic table, metals in group 2
Among these, lithium, sodium, potassium, magnesium, calcium, strontium, barium, and their oxides and hydroxides are preferred. The purification treatment may be carried out by a conventional method, but it can also be carried out in the presence of the above-mentioned basic substances, such as metal compounds, during distillation. In addition, purification can be performed using adsorbents such as clay, silica, alumina, and silica/alumina. Next, the fraction of the present invention obtained by the above method is dehydrogenated. A catalyst is used in the dehydrogenation reaction of the present invention, and any known catalyst can be used as the dehydrogenation catalyst. For example, oxides of metals such as chromium, iron, copper, potassium, magnesium, and calcium, noble metals such as platinum and palladium, or catalysts made of a combination of these metal oxides or noble metals with alumina are used. The reaction temperature for dehydrogenation is 350-650℃, preferably
The temperature is 400-600℃. When carried out using a fixed bed flow system, the LHSV is 0.2 to 10, preferably 0.5 to 3. During dehydrogenation, an inert gas such as water vapor can also be present. Further, an appropriate diluent can be used as necessary. In the dehydrogenation reaction of the present invention, the catalyst, reaction conditions, etc. may be appropriately selected so as to produce olefins such as monoolefins and diolefins, and to suppress side reactions such as decomposition and polymerization. Olefins are 0.5% by weight or more, preferably 5% by weight or more.
It is important to carry out dehydrogenation to produce at least % by weight. If the amount of the above olefins is less than 0.5% by weight, the effects of the present invention cannot be expected to be achieved. After completion of the reaction, if necessary, the dehydrogenated product of the present invention can be obtained by removing light components resulting from side reactions such as decomposition and heavy materials resulting from polymerization. The dehydrogenated product obtained as described above can be used as an electrical insulating oil as it is, or after being further fractionated into an appropriate fraction, or mixed with a dehydrogenated raw material oil. Furthermore, it can be used by mixing it with other electrical insulating oils in any proportion as long as they are mutually soluble. Other electrical insulating oils that can be mixed include known electrical insulating oils, such as mineral oils, olefin oligomers such as polybutene, alkyl or cycloalkylbenzenes such as dodecylbunzene and dicyclohexylbenzene, animal and vegetable oils such as triglycerides such as castor oil, These include phthalate esters such as dioctyl phthalate, silicone oil, etc. Other examples include saturated compounds having at least two fused or relatively fused aromatic rings, and aromatic olefins having at least two fused or relatively fused aromatic rings. The saturated compounds having at least two fused or specific fused aromatic rings include diphenylmethane, diphenylmethane substituted with a lower alkyl group such as benzyltoluene, 1-phenyl-1-xylylethane, 1-phenyl-1 -ethyl phenylethane, 1-phenyl-1-tolylethane, 1
-phenyl-1-isopropylphenylethane,
1-phenyl-1-trimethylphenylethane,
1,1-diphenyl ethane or 1, 2-diphenylethane or a lower alkyl substituted product thereof, diarylalkane or diarylcycloalkane such as 1,3-diphenylbutane, 2,4-diphenyl-2-methylpentane, diphenylcyclohexane, alkylaryl indan such as methylphenyl indan , biphenyl, alkyl or cycloalkyl biphenyl such as mono- or diisopropyl biphenyl, cyclohexine biphenyl, alkylnaphthalene such as mono- or diisopropylnaphthalene, ethers such as ditolyl ether, dixylyl ether, dibenzyl ether, diarylthioether, etc. and triarylalkane such as dibenzyltoluene, distyrenated xylene, bisphenethyltoluene, terphenyl, styrenated naphthalene, and triphenylhexane. Further, the aromatic olefin having at least two fused or non-fused aromatic rings,
Unsaturated dimers or trimers of styrenes such as 1,1-diphenylethylene, stilbene, styrene, α-methylstyrene and isopropenyltoluene, i.e. 1,3-diphenylbutene-1,2,4-diphenyl -4-methylpentene-1, etc., and 1-vinylphenyl-1-phenylethane, 1-isopropenylphenyl-1
Examples include vinyl phenyl phenyl alkanes such as phenylethane and vinyl phenyl phenyl methane, or lower alkyl group-substituted products thereof, and aromatic monoolefins such as isopropenyl biphenyl and isopropenyl naphthalene. Any of the above insulating oils can be mixed with the dehydrogenated product of the present invention either alone or as a mixture of two or more. In addition, antioxidants known as electrical insulating oils,
For example, as a phenol type, 2,6-di-tert-butyl-P-cresol (trade name BHT), 2,2'-
Methylenebis(4-methyl-6-tert-butylphenol), 4,4'butylidenebis(3-methyl-
6-tert-butylphenol), 4,4'thiobis(3-methyl-6-tert-butylphenol), stearyl-β(3,5-di-tert-butyl-4-hydroxyphenol) propionate (trade name)
Irganox 1076), Tetrakis [methylene-3 (3',
5′-di-tert-butyl-4′hydroxyphenyl)propionate]methane (trade name Irganox 1010),
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (trade name Ionox 330), 1,1,3
-Tris(2-methyl-4-hydroxy-5-tert-butylphenol)butane (trade name)
TopanolCA), sulfur-based compounds include dilaurylthiodipropionate, distearylthiodipropionate, laurylstearylthiodipropionate, dimyristylthiodipropionate, and phosphorus-based compounds include triisodecyl phosphite and diphthalate. Enylisodecyl phosphite, triphenyl phosphite, trinonylphenyl phosphite and the like can be added to the electrical insulating oil of the present invention. These antioxidants can be used alone or in combination of two or more, and the amount added is from 0.001 to 5% by weight, more preferably from 0.01 to 2.0% by weight, based on the insulating oil. Further, phosphoric acid ester compounds, epoxy compounds, and the like, which are known as additives for electrical insulating oils, may be used in combination for the purpose of imparting flame retardancy and other purposes. The electrical insulating oil of the present invention is suitable as a general electrical insulating oil, and is particularly suitable for impregnating oil-impregnated electrical equipment such as capacitors, cables, and transformers. As mentioned above, there has been a strong demand for higher voltage and smaller size in oil-impregnated electrical equipment in recent years, and with this, insulating paper has been used as an insulating material or dielectric material for oil-impregnated electrical equipment instead of conventional insulating paper. Plastics have come to be used in combination with Specifically, in capacitors, a combination of stretched or unstretched plastic film such as polypropylene, polymethylpentene, polyester, etc. and insulating paper is used as the insulator (dielectric material) of the capacitor, or these plastic films are used in combination with insulating paper. Furthermore, there are plastic films that are made with fine embossing to make them easier to impregnate, and metallized plastic films that use a surface metal layer as an electrode. Also, the cable (OF
(cables) in which polyolefin films such as crosslinked or uncrosslinked polyethylene, stretched or unstretched polypropylene, and polymethylpentene are used instead of insulating paper, and by melt extrusion of insulating paper and these polyolefins. Those using laminated films or composite films made by cross-linking insulating paper and silane-grafted polyethylene in the presence of a silanol condensation catalyst;
Alternatively, there is paper made of a mixture of paper pulp and polyolefin fibers. The electrical insulating oil of the present invention also has excellent compatibility with plastic, so it can be used in oil-impregnated electrical equipment that uses plastic as part or all of its insulator or dielectric, such as capacitors, etc. Suitable for impregnating cables, etc. That is, when a capacitor using plastic, particularly polyolefin, as part or all of the insulator (dielectric) is impregnated with the electrical insulating oil of the present invention, the swelling of the plastic insulator is small, so the insulating oil is sufficiently impregnated, and no voids (unimpregnated areas) occur. Therefore,
There is no risk of corona discharge resulting from electric field concentration in the void resulting in dielectric breakdown. Furthermore, the electrical insulating oil of the present invention has excellent hydrogen gas absorption properties and corona discharge resistance under high voltage, has a long life, and can achieve high pressure. Similarly, in the case of a cable, the dimensional change of the insulator due to swelling is small, so the oil flow resistance of the insulating oil is very low, and when the cable is impregnated with oil, the impregnation time with the insulating oil is shortened. Of course, since the impregnation is easily carried out, voids are less likely to occur, and the dielectric breakdown voltage is often increased. In addition, in cables using an insulator made of a laminated film of plastic film and insulating paper or a composite film, even if they come into contact with the insulating oil of the present invention for a long period of time, delamination, peeling due to bending, wrinkles, and buckling may occur. There is little risk that such things will occur. Furthermore, since insulating oil has excellent hydrogen gas absorption properties, it is possible to obtain a cable with excellent corona discharge resistance, similar to a capacitor. Therefore, a cable with a long life and high voltage can be obtained like a capacitor. Furthermore, by impregnating an insulating oil consisting of multiple components such as olefin, the above properties are improved as a synergistic effect between the components, and each component itself has excellent electrical properties, biodegradability, and heat resistance. In addition to maintaining properties and oxidation stability, the viscosity and pour point can be adjusted within suitable ranges, making it possible to manufacture oil-impregnated electrical equipment efficiently and easily, and to achieve high performance without being restricted by usage conditions. It is possible to obtain oil-impregnated electrical equipment that exhibits excellent performance. Next, the present invention will be further explained with reference to Examples and Comparative Examples. Example: Using aluminum chloride as a catalyst to obtain ethylbenzene for polystyrene, unreacted benzene, ethylbenzene, and polyethylbenzene were distilled off by vacuum distillation from the reaction solution in the process of reacting benzene with ethylene to produce ethylbenzene. Then, a fraction with a boiling point of 260 to 310°C calculated at normal pressure was collected. The main components contained in this fraction are 37% by weight of 1,1-diphenylethane and 32% by weight of 1-phenyl-1-ethyl phenylethane, especially 1,1-
Di(ethylphenyl)ethane, tetralin, indane, naphthalene, fluorene, alkyl-substituted products thereof, and substances of unknown structure were included. Next, the above recovered fraction was dehydrogenated in the presence of water vapor using a dehydrogenation catalyst under the following conditions. Catalyst: Nissan Girdler Catalyst Co., Ltd., G64A (iron oxide catalyst with potassium carbonate and chromium oxide as promoters) Temperature: 500°C LHSV: 1.0 H ₂ O/raw material: 3.0 (molar ratio) Pressure: Normal pressure After dehydrogenation, light and heavy components were removed to obtain a dehydrogenated product. The bromine number of this dehydrogenated product is 15.3cg/
(If all the olefins are mono-olefins, the olefin content corresponds to about 19% by weight).
Further, this dehydrogenated product was directly used as an electrical insulating oil for the following capacitor test. Capacitor Test A capacitor was impregnated with the dehydrogenated product and the recovered fraction before dehydrogenation as an insulating oil, and the performance was evaluated by making a capacitor as follows. Capacitors were evaluated using corona discharge onset voltage (CSV), corona discharge extinction voltage (CEV), and breakdown tests. The capacitor uses two layers of 14μ thick easily impregnated polypropylene film as the dielectric and aluminum foil as the electrode, impregnated with insulating oil, and the capacitance of the impregnated sundenser is 0.4μF.
I made it so that In the capacitor breakdown test, seven capacitors were each impregnated with the same oil, and the breakdown time of the capacitors was determined by applying a constant voltage to cause dielectric breakdown.
At this time, the highest and lowest breakdown times were excluded, and the average value of the values of the remaining five capacitors was taken as the breakdown time of the capacitor. Furthermore, the destruction time is expressed as a relative value, with the value of the sample impregnated with the recovered fraction before dehydrogenation being set as 1. Note that in all capacitor tests, 0.2% by weight of BHT was added as an antioxidant. The results are as follows. 【table】

Claims (1)

[Claims] 1. A monocyclic aromatic hydrocarbon is reacted with an alkylating agent in the presence of an alkylation catalyst, and mainly unreacted substances, mono- and polyalkylated monocyclic aromatic hydrocarbons, diaryl alkanes, and heavy An alkylated product containing the product is obtained, and then unreacted products, mono- and polyalkylated monocyclic aromatic hydrocarbons are separated and removed from the alkylated product, and the resulting fraction is dehydrogenated. A method for producing electrical insulating oil, characterized by: 2 The alkylated product is mainly benzene, ethylbenzene, polyethylbenzene, which is obtained by reacting benzene with ethylene,
A method for producing electrical insulating oil according to claim 1, wherein the product is a product containing 1,1-diphenylethane and heavy products. 3. The method for producing electrical insulating oil according to claim 2, wherein benzene and ethylene are reacted in the presence of an aluminum chloride catalyst in a temperature range of about 20 to 175°C. 4. The method for producing electrical insulating oil according to any one of claims 1 to 3, wherein the boiling point of the fraction obtained by separation from the alkylated product is in a temperature range of about 255 to 420°C. .