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(11) | EP 0 000 621 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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Liquid dielectric composition Flüssige dielektrische Zusammensetzung Composition diélectrique liquide |
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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 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). |
[0001] This invention relates to a liquid dielectric composition obtained from the alkylation product of benzene with ethylene.
[0002] Polychlorinated biphenyls have been extensively employed commercially in the electrical industry over a long period of time as liquid insulating fluids, but because of environmental and toxicological problems associated therewith, substitutes therefor are required.
[0003] 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.
[0004] In U.S. Patent No. 4,011,274, dated March 8, 1977, Masaaki et al recover from an alkylation product 1,1 -diphenylethane and state that the resulting residue is still available as a fuel.
[0005] Our European Patent Application No. 78300089.6 (publication number 0000622) describes how a liquid dielectric composition is 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-dipheny)ethane and higher molecular weight products, separating benzene, ethylbenzene and polyethylbenzenes from said alkylation product and thereafter recovering from the residual alkylation product 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.
[0006] In our European Patent Application No. 78300086.2 (publication number 0000619) we have described 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, separating benzene, ethylbenzene, polyethylbenzenes and 1,1-diphenylethane from said alkylation product and thereafter recovering from said higher molecular weight products a fraction having a boiling point in the temperature range of 275°C to 420 °C, preferably 280°C to 400°C, as said liquid dielectric composition.
[0007] According to the present invention there is provided 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 and higher molecular weight products, separating benzene, ethylbenzene and polyethylbenzenes from said alkylation product and thereafter recovering from said higher molecular weight products by distillation a fraction having a boiling point in the range of 255°C to 420°C, said fraction having dielectric properties, characterised in that said distillation is conducted in the presence of a basic material selected from the group consisting of Group I alkali metals and Group II alkaline earth metals, their oxides and hydroxides. Thus, we have found that if we remove from the alkylation product the unreacted benzene, ethylbenzene and polyethylbenzenes and then subject the residue to distillation in the presence of a basic material we can recover from said residue a fraction having a boiling point in the temperature range of 255 °C to 420°C,preferably 265°C to 400°C, most preferably 275°C to 400°C, as a liquid dielectric composition having an appreciably lower power factor than fractions not similarly distilled in the presence of a basic material, especialy when said liquid dielectric composition claimed herein is employed at high- ertemperatures.
[0008] Briefly, 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, polyethylbenzenes and heavier products, separating benzene, ethylbenzene and polyethylbenzenes from said alkylation product and thereafter recovering from said heavier products by distillation in the presence of a basic material a fraction having a boiling point at atmospheric pressure (ambient pressure) in the temperature range of about 255° to about 420°C, preferably about 265° to about 400°C, most preferably about 275° to about 400°C, as said liquid dielectric composition.
[0009] The alkylation of benzene with ethylene that can be employed to obain the new liquid dielectric compositions claimed herein can be any of the processes known in the art for producing a product containing ethylenzene, 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, prefeably about 10:1 to about 3:1. In the liquid phase reaction for example, the benzene and ethylene, together with an alkylation catalyst, for example, a Friedel Crafts catalyst, such as aluminum chloride, or aluminum bromide or some other organoaluminum halide; Lewis acid, such as promoted ZnCl2, FecI3 and BF3, 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, about 170x104 Pa), preferably about seven to about 200 pounds per square inch gauge (about 0.5 to about 14 kilograms per square centimeter that is about 5x104 Pa to about 140x104 Pa), for about ten minutes to about ten hours, preferably for about 20 minutes to about three hours. In the vapor phase, for example, 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 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 265x104 Pa to about 830x104 Pa), preferably about 600 to about 1000 pounds per square inch gauge (about 42 to about 70 kilograms per square centimeter that is, about 410x104 Pa to about 690x104 pa).
[0010] As a result of such reactions, an alkylation product is obtained containing unreacted benzene, the desired ethylbenzene, polyethylbenzenes, such as diethylbenzene and triethylbenzene, and higher-boiling products.
[0011] The alkylation product can be treated in any conventional manner to remove any alkylation catalyst present therein. For example, when aluminum chloride is used as catalyst, 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.
[0012] The resulting alkylation product is then distilled 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).
[0013] 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. To obtain the claimed novel liquid dielectric composition, the said heavier product is simply subjected to distillation in the presence of a basic material and those portions recovered having a boiling point at atmospheric pressure (14.7 pounds per square inch or 760 millimeters of mercury that is 10.13x104 Pa) in the temperature range of about 255° to about 420°C, preferably about 265° to about 400°C, most preferably about 275° to about 400°C, constitute the desired and novel liquid dielectric composition. The remaining heavier material or residue is a black asphalt-like material solid at ambient temperature believed, in part, to be polynuclear structure having fuel value only.
[0014] The basic material present during the distillation defined above is selected from the group consisting of Group I and Group II alkali metals and alkaline earth metals, their oxides and hydroxides. Of these lithium, sodium, potassium, magnesium, calcium, strontium and barium, their oxides and hydroxides are preferred. The amount of basic material in the distillation zone can be, for example, in the range of about 0.5 to about 20 weight per cent, preferably about one to about 10 weight per cent, based on the weight of the charge being subjected to distillation. Preferably the distillation is carried out while stirring the mixture or in the presence of boiling chips to avoid bumping. If desired reduced or increased pressure can be used during the distillation, with the temperature being correlated therewith so that the material distilled off and recovered herein will be those portions of the heavier product, defined above, corresponding to those portions having a boiling point at atmospheric pressure of about 2550 to about 420°C, preferably to about 265" to about 400°C, most preferably about 275° to about 400 °C. The residue remaining after such distillation is a black asphalt-like material solid at ambient temperature having fuel value only.
[0015] If is critical herein that said distillation be carried out in the presence of the basic material defined above. If the bottoms to be distilled are treated with the basic material prior to distillation emulsion problems result, and it is then difficult to separate the two phases. If, on the other hand, the bottoms are first distilled and the desired fractions are then treated with the basic material, it is exceedingly difficult to remove the last traces of basic material from the desired fractions, causing the material to lose some of its insulating capability. In addition such treatment also results in emulsion problems.
[0016] 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 of9:1 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, 48x104 Pa) in the presence of AICI3 catalyst over a period of one hour, which was sufficient to convert all of the ethylene. The AICI3 complex catalyst was prepared by dissolving AICI3 in a polyethylben- zene cut from a previous run so that after the addition the composition of the catalyst complex was as follows: 31.5 weight per cent AICI3, 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 AICI3 present in the catalyst mixture amounted to 0.0034 parts by weight per one part by weight of ethylbenzene produced. Also present in the catalyst was 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 triethylbenzenes, 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, ethylbenzene 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. By using aged aluminum chloride complex, the amount of high-boiling residue formed can be increased substantially.
[0017] The residue obtained was subjected to distillations at atmospheric pressure arbitrarily to obtain selected cuts thereof. One cut (Run No. 1 in the Table below) was untreated. Another cut (Run No. 2) was washed three times with a 10 per cent aqueous sodium hydroxide solution prior to distillation. A third cut (Run No. 3) was washed three times with a 10 per cent aqueous sodium hydroxide solution, then with water and dried. The remaining cuts (Runs Nos. 4, 5, 6, and 8) were distilled in the presence of selected basic materials at atmospheric pressure. Each of the above was subjected to tests (ASTM-D924) at 25° and 100°C to determine its power factors and dielectric strenght. The results obtained are set forth below in the following Table.
Referring to the above, in Run No. 2 the procedure was difficult to carry out because of emulsion problems. Some emulsion problems were also noted in Run No. 3. It can be seen from the data in the Table that greatly improved results are obtained when the dictates of the process employed herein are adhered to. In Run No. 1, wherein the defined cut was not treated, the product possessed an excellent dielectric strength and a good power factor at 25°C. Its power factor at 100°C was somewhat high. Although there was a slight improvement in the power factor at 100°C in Run No. 2, as noted emulsion problems were encountered. When the defined cut was treated with sodium hydroxide in Run No. 3 after distillation, its dielectric strength and power factors were adversely affected. However, in each of Runs Nos. 4 to 8 when the distillation was carried out in the presence of the basic material distillation cuts were obtained having improved power factors at 25° and 100°C. In each of Runs 4 to 7 excellent dielectric strengths were obtained. Although no measurement was made of the dielectric strength of the cut in Run No. 8, it is believed the dielectric strength thereof would have been on the same levels as in Runs Nos. 4to 7.
1. 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
and higher molecular weight products, characterised in that benzene, ethylbenzene
and polyethylbenzenes are separated from said alkylation product and thereafter there
is recovered from said higher molecular weight products by distillation a fraction
having a boiling point in the range of 255°C to 420°C, said fraction having dielectric
properties, said distillation being conducted in the presence of a basic material
selected from the group consisting of Group I alkali metals and Group II alkaline
earth metals, their oxides and hydroxides.
2. The composition of claim 1 wherein said fraction has a boiling point in the range
of 265°C to 400°C.
3. The composition of claim 2 wherein said fraction has a boiling point in the range
of 275°C to 400 °C.
4. The composition of claim 1 wherein said basic material is selected from the group
consisting of Group I alkali metals, their oxides and hydroxides.
5. The composition of claim 1 wherein said basic material is selected from the group
consisting of Group II alkaline earth metals, their oxides and hydroxides.
6. The composition of claim 5 wherein said basic material is CaO.
7. The composition of claim 4 wherein said basic material is NaOH.
8. The composition of claim 5 wherein said basic material is BaO.
9. The composition of claim 4 wherein said basic material is KOH.
10. The composition of claim 1 wherein said catalyst is AICI3.
11. The composition of claim 1 wherein said benzene and said ethylene are reacted
in the presence of AICI3 in a temperature range of about 20 to about 175°C.
12. The composition of claim 11 wherein said benzene and said ethylene are reacted
in the presence of AICI3 in a temperature range of about 90° to about 150°C.
1. Composition de diélectrique liquide obtenue comme le résultat d'un procédé selon
lequel on fait réagir le benzène avec l'éthylène en présence d'un catalyseur d'alkylation
pour obtenir un produit d'alkylation contenant du benzène inaltéré, de l'éthylbenzène,
des polyéthylbenzènes et des produits à poids moléculaire élevé, la composition étant
caractérisée en ce que, pour l'obtenir, on sépare le benzène, l'éthylbenzène et le
poly- éthylbenzène du produit d'alkylation, puis l'on recueille, à partir de ces produits
à poids moléculaire élevé, par distillation, une fraction dont le point d'ébullition
se situe entre 255°C et 420°C, cette fraction ayant des propriétés d'un diélectrique
et la distillation étant conduite en présence d'une' matière basique choisie parmi
les métaux alcalins du groupe I, les métaux alcalino-terreux du groupe II, leurs oxydes
et leurs hydroxydes.
2. Composition selon la revendication 1, caractérisée en ce que la fraction présente
un point ou gamme d'ébullition se situant entre 265°C et 400°C.
3. Composition selon la revendication 2, caractérisée en ce que la fraction présente
un point ou gamme d'ébullition se situant entre 275°C et 400°C.
4. Composition selon la revendication 1, caractérisée en ce que la matière basique
est choisie parmi les métaux alcalins du groupe I, leurs oxydes et leurs hydroxydes.
5. Composition selon la revendication 1, caractérisée en ce que la matière basique
est choisie parmi les métaux alcalino-terreux du groupe Il, leurs oxydes et leurs
hydroxydes.
6. Composition selon la revendication 5, caractérisée en ce que la matière basique
est CaO.
7. Composition selon la revendication 4, caractérisée en ce que la matière basique
est NaOH.
8. Composition selon la revendication 5, caractérisée en ce que la matière basique
est BaO.
9. Composition selon la revendication 4, caractérisée en ce que la matière basique
est KOH.
10. Composition selon la revendication 1, caractérisée en ce que le catalyseur est
AICI3.
11. Composition selon la revendication 1, caractérisée en ce qu'on a fait réagir le
benzène et l'éthylène en présence de AICI3 à une température comprise entre environ 20° et environ 175°C.
12. Composition selon la revendication 11, caractérisée en ce qu'on a fait réagir
le benzène et l'éthylène en présence de AICI3 à une température comprise entre environ 90°C et environ 150°C.
1. Flüssiges Dielektrikum, das erhalten worden ist als Ergebnis eines Verfahrens,
bei dem man Benzol mit Äthylen in Gegenwart eines Alkylierungskatalysators umsetzt
und ein Alkylierungsprodukt erhält, das nicht umgesetztes Benzol, Äthylbenzol, Polyäthylbenzole
und Produkte von höherem Molekulargewicht enthält, dadurch gekennzeichnet, dass man
das Benzol, das Äthylbenzol und die Polyäthylbenzole vom Alkylierungsprodukt abtrennt
und anschliessend von den höhermolekularen Produkten durch Destillation eine Fraktion
gewinnt, die einen Siedepunkt im Bereich von 255° bis 420°C und dielektrische Eigenschaften
hat, wobei man die Destillation in Gegenwart eines basischen Materials durchführt,
das aus der aus Alkalimetallen der Gruppe I und Erdalkalimetallen der Gruppe II, ihren
Oxiden und Hydroxiden ausgewählt ist.
2. Dielektrikum nach Anspruch 1, dadurch gekennzeichnet, dass die Fraktion einen Siedepunkt
im Bereich von 265° bis 400°C hat.
3. Dielektrikum nach Anspruch 2, dadurch gekennzeichnet, dass die Fraktion einen Siedepunkt
im Bereich von 275° bis 400°C hat.
4. Dielektrikum nach Anspruch 1, dadurch gekennzeichnet, dass das basische Material
aus der aus Alkalimetallen der Gruppe I, ihren Oxiden und Hydroxiden bestehenden Gruppe
ausgewählt ist.
5. Dielektrikum nach Anspruch 1, dadurch gekennzeichnet, dass das basische Material
aus der aus Erdalkalimetallen der Gruppe II, ihren Oxiden und Hydroxiden bestehenden
Gruppe ausgewählt ist.
6. Dielektrikum nach Anspruch 5, dadurch gekennzeichnet, dass das basische Material
CaO ist.
7. Dielektrikum nach Anspruch 4, dadurch gekennzeichnet, dass das basische Material
NaOH ist.
8. Dielektrikum nach Anspruch 5, dadurch gekennzeichnet, dass das basische Material
BaO ist.
9. Dielektrikum nach Anspruch 4, dadurch gekennzeichnet, dass das basische Material
KOH ist.
10. Dielektrikum nach Anspruch 1, dadurch gekennzeichnet, dass der Katalysator AICI3 ist.
11. Dielektrikum nach Anspruch 1, dadurch gekennzeichnet, dass man das Benzol und
das Äthylen in Gegenwart von AICI3 in einem Temperaturbereich von etwa 20° bis etwa 175°C umsetzt.
12. Dielektrikum nach Anspruch 11, dadurch gekennzeichnet, dass man das Benzol und
das Äthylen in Gegenwart von AICI3 in einem Temperaturbereich von etwa 90° bis etwa 150°C umsetzt.