DE2357477A1 - PROCESS FOR MANUFACTURING ISOTROPIC COAL - Google Patents

Description

j. P. WSRTH · or. V. SGHMSED-KQWARZiK DlpWng. G. DANNENBERG -Dr. P. WEIN HOLD Dr. D. GUDEL

281334 '6 FRANKFURTAM MAiM

coera

237314 QR. ESCHENHEIMER STBASSE 30

SK / SK 70T387-C

Koppers Company, Inc. 1450 Koppers Building Pittsburgh, Pa 15 219 / USA

Process for the production of isotropic coal

The present invention relates to isotropic carbon fibers and to methods of making them from liquid hydrocarbon des txliat en «

Carbon fibers have been known since 1880 when Thomas Edison first made it Once I used a carbon fiber as a filament for a light bulb. At present, carbon fibers are also being used in hard materials. incorporated, e.g. Metals, polymers, carbon, graphite, ceramics, etc., in order to create structures reinforced with carbon fiber with improved mechanical, to maintain thermal and electrical properties. Such structures are especially used in the modern space industry used as a thermally stable material.

So far, too, have basically been different threads made of coal "One type is known and is known as carbon fiber made by baking carbonaceous materials at a relatively low temperature (about 1000 ° C.); the second type is known as graphite fiber and is obtained by heating the carbon fibers to relatively high temperatures (about 2500 ° C «or

OFIIGINAL INSPECTED

higher). The graphite fibers are stronger than carbon fibers. Graphite fibers have a tensile strength of about 5600-11 200 kg / cm ² and a modulus of elasticity of about 3.5-7 10 kg / cm while carbon fibers have a tensile strength of about 5600-11 200 kg / cm and a modulus of elasticity of about 0.42 -0.56 x 10 kg / cm.

As used herein, "isotropic carbon" refers to on elementary carbon with a physical structure such that it has the same physical structure in any given spatial direction and has chemical properties. In appearance, isotropic carbon is a hard, vitreous, infusible, shiny, Protective substance. Whether a finely divided carbon sample isotropic carbon or anisotropic carbon (i.e. having a physical structure such that it has different physical and chemical properties according to its structural orientation shows) is determined by microscopic examination in a metallographic microscope. Usually the carbon sample is placed on an epoxy resin type carrier buffed / and polished to a mirror-smooth surface finish, The polished surface is done in reflected polarized light with crossed Nicol prisms under a usual metallographic Examines microscope. If the sample is isotropic carbon, there is no change in the when the sample is rotated Intensity of reflected polarized light; however, the intensity of the reflected polarized light changes when If the sample is rotated, it is anisotropic carbon "

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Another unique property of isotropic carbon

("graphitizing")

is that he is not graphite-forming / _e is generally carbons can be classified as graphite-forming and non-graphite forming carbon "graphite-forming carbons are Z ₀ as pitch and Erdölkokse" Not gi ^ hitbildende carbon for _a B "of polyvinylidene chloride, cellulose ^ Sucrose usuj. derived carbons. The term soft carbon is also often used for graphite-forming carbons, while non-graphite-forming carbons are known as hard carbon or turbostratic carbon. Isotropic carbon can only be partially graphitized with difficulty "If isotropic carbon is ^{subjected to temperatures of 2500 0} C ₀ or more; then graphite is only formed to a very limited extent."

Furthermore, isotropic carbon is characterized in that It is very resistant to attack by strong mineral acids including hydrofluoric acid. “It also has a lesser one Oxidation rate than other forms of carbon. the internal friction of isotropic carbon is only a fraction (about 1/4) that of other non-crystalline carbons.

Isotropic carbon is not new and known from the literature (see, for example, the article by T. Yamaguchi in "Carbon", Vol ₈ 1, 47-50 (1963) and dsn article by T. Tsuzuku and H Kobayashi in "Proceedings of the Fifth Carbon Conference ", page 539, and the article by Fitzer, Schoefer and Yomada in" Carbon ", Vol. 7, pages 643-648 (1969). Furthermore, isotropic carbon is the subject of various patents, such as z _o B _e the british

409837/0689

1 182 455 .-- 4 -

Patent specification / that on the production of isotropic carbon is directed from pitches unreacted with ammonium sulphate, and the US Pat. No. 3,284,371, which refers to isotropic carbon for -alektrographitische brushes bzu / "Brush is set up"

So far, the most common method of making isotropic has existed Carbon in the carbonization ί / οη highly cross-linked macromolecular structures that contain carbon and hydrogen still contain oxygen, nitrogen or sulfur. The carbonization these components form firmly crosslinked aromatic Levels that prevent the transformation in the graphite structure i / c Examples of some of these compounds are sucrose, Cellulose Rayon, Furfuralphenol Resin Phsnoifcrtnaldehydhaxrze, Acetone furfural polymers, polyvinyl chloride, polyvinylidene chloride and polyacrylonitrile.

Carbon fibers are also known * cf. * e.g. the article by B. Otani in "Carbon", Vol. 3, pp. 31-38 (1965); "CarboR- ^11, 3d 3, side- 213;. And." Carbon "8d _o 4y page 425-532 (1966) Also, several recent patents are directed to carbon fibers, such as US-Patentschriftsn 5,392,216 and 3,629,379 , 3 595 and 3 668 110. None of the fibers mentioned above are, however, isotropic carbon fibers, which are produced from carbon hydrogen distillates and / or

The aim of the present invention is therefore the formation of isotropic Fibers and a process for their production from liquid Carbon dioxide distillates.

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The present invention relates to isotropic carbon fibers and a method for their preparation from liquid Kohlenu / asserstoffdestillaten ₀ This method is characterized in _p that a hydrocarbon distillate with a 8Ot ₂ elementary oxygen-containing gas at a reaction temperature of etuja 250-42O ⁰ C ₀ until the distillate obtained provides isotropic carbon after subsequent carbonization. this

Oj0283 no

means, that at least about 0.5 standard cubic foot (scf) / elemental oxygen have reacted with 0.454 kg of distillate to form a pitch-like substance, then the pitch-like oxidized distillate is deformed into threads and finally added in an inert atmosphere Temperatures over 80Q ⁰ C. for the formation of isotropic carbon fibers carbonlslext.

According to a preferred method according to the invention, a selected Hydrocarbon distillate converted from a substance with oily properties into a substance with pitch-like properties by treating the distillate with a, elemental oxygen containing that at elevated temperatures and pressures sufficient to suppress the evaporation of the distillate at the elevated temperatures - until the distillate is converted into a Pitch-like substance changed Afterwards, the low-boiling components of the oxidized distillate are oxidized from the pitch-like Distillate distilled off. The one left over from the distillation Substance with pitch-like properties becomes one Extruded thread j its tendency to melt or sinter uiird suppressed., so that the thread after the subsequent carbonization retains its shape * Then the thread is

Erten atmosphere at temperatures over 800 ⁰ C. carbonized to form an isotropic carbon filament "The amount of the Kohlenli / asserstoffdestillat unreacted elemental oxygen is at least about 0.5 scf elemental oxygen per 0.454 kg distillate. The oxygenation reaction takes place at a temperature of about 250-420 ° C.

The initial stage in the process of the invention is the reaction of the carbon distillate with oxygen, The implementation of carbon / hydrogen distillates with oxygen is not new and frequently described (see e.g. the US patents directed to the reaction of oxygen and carbon dioxide distillates 1,044,175, 3,304,191, 3,304,192, 3,510,328, 3,112,181, and 3,707,388. However, none of the above patents teach the critical one Importance of oxygen concentrations in the production of isotropic carbon. In fact, neither of those says above patents etiuas about isotropic carbon from, and many of the oxidized distillates are expressly referred to as graphitizable. designated..

The term "carbon dioxide distillate" used here refers to both coal tar distillates and petroleum distillates. The term "coal tar distillates" refers to the distillate substances derived from the distillation of coal tar. The term "petroleum distillate ^11" refers to the material separated from a crude or synthetic petroleum by physical means, such as distillation or extraction.

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=. 7 -

According to the invention, both coal-tar can and petroleum distillates used, "according to the invention preferred Kohleteerdestillate are the distillate oils J they usually include the so-called _e slight ion ^ medium and heavy Teerölfrakt with a boiling point range of 200-40O ⁰ C ₀ ·" These fractions are from numerous Sources readily available in stores. The physical properties of a typical coal tar distillate in the original, unoxidized state and after reaction with the minimum oxygen concentration suitable for use according to the invention are listed in the following table;

Table 1

physical properties coal tar distillate oxidized

Coal tar style - lat

Softening point (ring &. _Rn * on ° r

in benzene insol ₀ Material ₀ track 20j, 0-40 _s 0 wt -.%

in quinoline insoluble materialo trace. 0 ₉ 3-0 ₉ 5 & ew ° -% +

Conradson C ^ U. 2-5 % 30-50 Geui, ~% distillation (ASTM D246)

Initially boiling point 200 ⁰ Co

cumulative distillate

• up to 21O ⁰ C. 0 % -

up to 235 ⁰ C ₉ -2.1 %

to 270 ⁰ C.. _ '' ■ 12 ₉ 6 %

up to 315 ⁰ Co 36.3% 3.3 %

to 355 ⁰ C. 80,2-Ji 38 _r 2 %

Residue over 355 ⁰ C. 19 ₂ 2 55.0 to 70%, ^1% O Elementarzu composition ι wt .- / ο

Carbon 89.0-94 ₉ 0 90.0-92.0

Hydrogen 4.0-7.0 4.0-5.0

Oxygen. 1.0-2.0 2 _s 0-4.0

Sulfur 0.2-0.8 0.2-0.6

Nitrogen 1.0-2.5. 1.0-1.5

■ "" "" '408837/0669

The preferred according vsxsjandatsn petroleum distillates are boiling between 200-600 ⁰ C. ^Sl sfcraight ~ run "distillates and between 200 to 500 ⁰ C _9-boiling" catalytic cracked recycle oils. These distillates are readily available from commercial sources sahlrsiehsn the physical. Properties of a typical petroleum distillate in the original, unoxidized state and after reaction with the minimum oxygen level for use according to the invention are listed in the following table:

physical properties petroleum-style oxidised petroleum Distillate

Pour point; ⁰ C. ~ 73

Dastillate range (ASTM D246)

initial boiling point; ° C »26? 233

Cumulative distillate; %

to 27O ³ C.. up to 300 ⁰ C.

up to 315 ⁰ C.

up to 355 ^G C.

up to 375 ° C.

The decisive feature of the present invention is the amount of elemental oxygen which must combine with the carbon-hydrogen distillate to form the pitch-like substance. It tuurde found that at least 0.5 scf elemental oxygen per 0.454 kg Kohleniuasserstoffdestillat in the contact reaction with the Kohlenuiasssrstqffdestillat reacted u / ground must ₉ to form a pitch-like substance, which is a satisfactory ΐ / orläufer for the manufacture of isotropic carbon. With a reaction of less than 0.5 scf oxygen per 0.454 kg distillate, the product obtained gives anisotropic carbon in the subsequent carbonization. The consumption of one

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8.1 47j3 19.2 78.9 30.3 87.5 44.6

Tarem oxygen is expediently used by oxygen equilibrium as Difference between that introduced into the carbon dioxide distillate Amount of elemental oxygen and the amount of elemental Oxygen measured ^ which the carbon distillate after the reaction of the oxygen-containing gas with the distillate leaves".

The gaseous, elemental oxygen suitable according to the invention can be pure gaseous oxygen or a combination of this with other gases «The preferred oxygen-containing one From an economic point of view and from the point of view of handling the materials, gas is air «,

In the preferred Aosführungsform the present invention, 'air is uniformly through the Kohlenujasssrstof fdestillat dispersed by air initiates at a temperature of 250-420 ⁰ C. in the hydrocarbon distillate j, the preferred temperature-^ raturbereich is about 350-370-Jedoch'zwischen ° C «In this preferred temperature range, the reaction rate of the elemental oxygen with the carbon distillate is so fast that the concentration of residual oxygen in the exiting gases can be kept below the lower explosion limit of exhaust gases that are saturated with hydrocarbon vapors, for suppression the 1 / ardarabgabe the hydrocarbon distillate at this temperature, the air can be introduced under pressure, preferably at 5.60-7.00 at. To achieve a high reaction rate, the air should be dispersed in fine and intimate dispersion throughout the hydrocarbon distillate =, . ·

Make the intimate contact of air with the invention Kohlsnufasssrstoffd8stiliat changes this from an oily one Liquid to a pitch-like substance, with such physical Properties ^ that they are a good precursor for manufacture is of isotropic carbon. Typical properties of the pitch-like substance (i.e. the oxidized carbon distillate) are shown in the two tables above.

The way by which the liquid hydrocarbon distillate in a pitch-like substance is not entirely known. It is assumed, however, that the oxygen is responsible for the formation induced free radicals from carbon dioxide molecules, which easily combine again and the molecular weight "of the distillate raise. Part of the oxygen reacted with the distillate then escapes from it in the exhaust gases in the form of Steam; however, some of the oxygen remains in the pitch-like state Incorporated substance. This oxygen, which remains in the pitch-like substance, presumably contributes to the greasy Graphitization of the isotropic carbon when it is pyrolyzed in an inert atmosphere.

In most cases the crude oxidized distillate will comprise one Main part of relatively higher-boiling components and a smaller proportion of relatively lower-boiling components. Once in a while These lower-boiling components must be oxidized from the crude, preferably by conventional distillation processes Distillate are removed in order to increase the viscosity and softening point of the oxidized distillate so that it is subsequently can be continued without difficulty.

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The softening point (cube in air) of the destilliertenn oxidized distillate after the distillation was about 80-200 ⁰ C ₀ ⁰ C ₀ 120-170 preferably ettua j, amount ", whereas the softening point is over 200 ⁰ Cp is then distilled oxidized distillate too hard and stiff for subsequent deformation purposes «

Then u / ith the oxidized distillate by extrusion through a spinning head or socket having a plurality of nozzle openings at temperatures between etu / a deformed into a thread 120-300 ⁰ C _0th Usually, the temperature of the oxidized aromatic distillate is kept for about 40-50 ⁰ Co ,, above its softening point so that the oxidized distillate good spinning properties, "The threads of each opening be appropriately collected and connected to a winding apparatus of a high speed ^ the threads which pulls through the spinning head and winds it up on a bobbin which is located on the winding device. Therefore the threads are under tension, and this tension reduces the thread diameter to a value _s which is considerably smaller than the diameter of the openings. The diameter represents threads can therefore by controlling the temperatures of the oxidized distillate through the orifice size of the spinning head and the velocity., _S at which the threads are drawn by the winder from the apertures be accurately regulated.

After deformation, the oxidized distillate becomes a thread this treated if necessary so that it better bsuemen its shape during the subsequent carbonization. To do this is the softening point the exposed thread surface is increased by

4098 37/066

to this a gas, preferably a relatively hot air stream having a temperature of 130-150 ⁰ C. etum can impinge. The gas preferably simply flows along the filament, since it is believed that the hot air current briefly impacting the filament surface removes all lower boiling components therefrom and induces the formation of free radicals described above, which react with and absorb other hydrocarbon molecules near the filament surface convert an infusible layer.

Then the threads are heated to at least about 800 C. carbonized in an inert atmosphere for a short time »The threads carbonized in this way have such physical properties, that they are suitable for many uses. Typical properties of the isotropic carbon filaments produced according to the invention are as follows:

Diameter 5-15 microns

Elongation at break 1.2-2.0 %

Modulus of elasticity; kg / cm ² 420,000-560,000

Tensile strenght; kg / cm ² 7000-12 600

Elemental composition j %

Carbon 93.0-97.0

Hydrogen 0.2-0.6

Oxygen 0.5-3.0

Sulfur less than 0.6

Nitrogen less than 0.2

The accompanying drawing is a schematic representation of a device used according to the invention.

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.- '- 13 -The The device consists essentially of a Uorerhitzer 11, a pressure vessel 13, a distillation unit 15, a thread extruder 17 and a winding device 19 «,

The Uorerhitzer 11 is a conventional system, the crude distillate "DIE to about 250-400 C. ⁹ heated. The vessel 13 is a conventional pressure tank. The Uorerhitzer 11 is connected through line 21 to the bottom of vessel 13. The vessel 13 is connected at its bottom to an air source through line 23. The air flow through line 23 into the vessel 13 is regulated by a control device 25 and the valve 27.

At the top of the vessel 13, a line 29 leads the exhaust gases from the vessel 13 into a heat exchanger 31, whereupon these gases are then Be released into the atmosphere via the UBntil 33. An oxygen analyzer 35 determines the concentration of elemental oxygen in the exhaust gases passing through line 29. That Vessel 13 has a conventional temperature measuring device 37 and a conventional pressure measuring device 39 for monitoring temperature and Pressure in the vessel 13.

At the bottom of vessel 13 there is a line 41 and a U-part 43 for drawing off the oxidized distillate from the vessel 13. The oxidized distillate is fed into a storage tank 45 and then into the distillation unit 15. The softening point of the crude oxidized distillate is through in conventional distillation unit 15 is set to about 80-200 ⁰ C.. The distillates are withdrawn from the unit and returned in the manner described, and the residue from the distillation continues to run into the extruder 17. The extruder 17 comprises means

40983 7/066 9

such as an electric furnace (not shown) for heating and maintaining the temperature of the oxidized distillate at etura 120-30G ^D C. At the bottom of the extruder 17 is a conventional spinning head 51 with at least one, preferably a plurality of nozzle openings of about 500 microns in diameter provided, through which the oxidized aromatic distillate to form the thread F is extruded u / ird. The extruder includes a conventional temperature and pressure measuring device 53 and 55, respectively, for monitoring the temperature and pressure therein. A pressure source 57 is in communication with the extruder through line 59 to provide the pressure necessary to extrude the oxidized aromatic distillate through the spinneret 51. The pressure source is preferably pressurized gaseous nitrogen.

Below the extruder 17 is Bin's winding device 19 with a bobbin 61 and a motor 63 for rotating the bobbin 61. The thread F uiird, u / ie shown, on the bobbin 61 collected.

In a preferred embodiment of the present invention, a Kohlenu is / asserstoffdestillat through the preheater 11 and heated there to approximately 350-370 ⁰ C., whereupon it then represented uiie is discharged through line 21 into the vessel. 13 The pressure in the vessel is increased to about 6-7 atm, which is sufficient to suppress the evaporation of the aromatic distillate at this elevated temperature.Air is introduced at the bottom of vessel 13 through line 23 into a plurality of openings (not shown), to ensure intimate mixing of the same with the distillate. The air-

409837/0669

fluQ into the vessel is regulated by the flow regulator 25 at the preferred rate of about 0.2-2.5 scf of air per hour per hour
0.454 kg of distillate held. After the air the distillate on
Entering the bottom of the vessel, it runs upwards through the distillate and converts it into a pitch-like substance. The ones from the
Vessel 13 exiting gases run through line 29 into the heat exchanger 31, and / or they are cooled, and from there to the analysis device 35, where they are analyzed for oxygen content.
The oxygen concentration of the gases should be kept fourth below the explosive limits in vessel 13. Like the air
rises upwards through the distillate in vessel 13, the viscosity of the distillate and the amount of components insoluble in benzene in the distillate increases,

If the viscosity of the distillate about 30 _sec converted as TO Saybolt seconds at 100 ^Q C. and the benzene-insolubles 0 wt .-% rüfneTchen "," Tst Däs ~ DesTiilat suitable as precursors for the manufacture of isotropic carbon filament into a pitch-like substance . In the Parxis, however, the amount of oxygen consumed is the determining factor "when deciding whether to use the distillate
has been adequately treated. If more than 0.5 scf of elemental oxygen per 0.454 kg of distillate has been consumed, the air flow through valve 27 is interrupted and the pressure in vessel 13 is reduced through valve 33. The contents of the vessel are through
Line 41 is led to a storage tank and from there into the distillation unit 15, where the lower-boiling components are removed and a residue with the desired softening point is obtained.

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When the threads F in the drawing are extruded, it becomes oxidized Distillate extruded through the nozzle openings of the spinning head 51. At the beginning of the process, the thread end is connected to the bobbin 61. Operation of motor 63 turns spool 61 on a special speed so that the thread by tension from its original thread size of 500 microns on a Diameter of 10-15 microns is drawn.

Then the spool 61 is removed from the winding device 17; the threads on the coil are brought into contact with hot air, and then carbonized at temperatures over 800 ⁰ C.. The carbonized thread obtained is infusible, shiny black, hard and generally has the properties of isotropic carbon.

The following examples illustrate the present invention, without restricting them.

Example 1_

A number of carbon filaments of different diameters were produced according to the method of the invention. The starting material was a coal tar distillate. This was done with oxygen (air) at a temperature of about 360 ° C. implemented until more than 0.5 scf of elemental oxygen per 0.454kg of distillate had been converted. Then the oxidized distillate was used to remove the low. Subject the boiling components to vacuum distillation. The filaments were then made by spinning the oxidized distillate and then carbonized under a nitrogen atmosphere in a tubular furnace at a temperature of up to 520 ° C. 1 ° C. / min and up to 1000 ⁰ C. 3 ° C. / tNin each was increased.

409837/0669

The mechanical properties of the threads were measured by mounting each thread on cardboard using an epoxy resin to hold each thread at two points 2.5 cm apart. The cardboard had a cut-out slot along its length ./The sides of the carton and / ere cut so that the yarn aperen [äi§ ih ^ ^ ^ ig_e3V bindyng_ "zvuischenf deri and lower parts remained the yarn were tested under the following conditions.:

Measuring length 2.5 cm

Crosshead speed 0.5 mm / min

Instron load cell type C

Measurement card speed 12.5 cm

Total deflection of the measuring card 100 g

The results are shown in Table 1. For comparison, the data for carbon fiber made of rayon (A) and carbon fiber, made according to US Pat. No. 3,629,379 from pitch (B). Also the density and final analysis of the various Carbon threads are indicated. All carbon thread were in an epoxy resin embedded and under a magnification of 800 with polarized Light and crossed Nicol prisms examined in a metallographic microscope. The results show that the invention Carbon filaments are isotropic.

/ The box was in the holders of an Instron Universal Sensing device mounted.

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• 2357477 Properties of carbon threads final tensile strength
speed; kq / cm % 98.3 99 Elasticity modulus
1000 kq / cm 490 + 28 - - 18 - Product mechanical properties 8050 + 1260 0.49 0 493, , 5 + 56 Table 1 diameter
Micron 8470 + 140 <O, 1O <0 602 + 105 A 8 9310 + 1610 . <0.30 <0 511 + 42 B 9-14 7000 + 1050 1.05 0 406 i 46.2 Example 1 16-18 6860 + 70 490 + 49 20-22 6930 + 1400 350 i 35 24-26 4900 + 70 315 + 49 33-35 4200 + 70 385 + 35 40 4200 + 140 342 + 14 45-46 4200 + 420 280 4 28 50 4200 + 560 287 t ^ß3 53-55 2800 + .210 A. 59-60 Example 1 B 68-70 1.56 1 , 61 99.57 Density; g / ccm , 96 0.22 final analysis; , 28 <0.10 C. , 10 <0.30 H , 30 N , 44 S. 0 (direct)

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Example 2

According to Example 1, a number of carbon threads were produced, wherein the only difference was that the filaments after their deformation, but before carbonization with warm air were treated. The threads obtained had the same properties as those of Example 1. The advantage of this treatment with air is that it reduces the tendency of the threads to

(Gluing)
melting / decreased during carbonization.

The graphitization index "g" was used for a Sample of isotropic carbon determined on the basis of X-ray data (measured after heating the carbonized Product at 3000 C in an inert atmosphere); it was about 0.12. For carbon which can be graphitized, the value is g = 1. The index was calculated from the following formula:

₌ Λ. 002 - 3.35
3.45-3.35

where <i 002 is the average distance between two graphite

O
planes is; 3.45 A is the distance between the planes at the beginning of the graphitization while 3.35 S is the distance between the planes at the end of the graphitization. The value of d 002 was calculated from the Brugg equation:

d 002 = -

002 where X is the wavelength of the X-rays; o (002 is the

angle corresponding to the maximum of the 002 apex. The Kristallat-Lc

size / is for the isotropic carbon according to the invention 60 R compared to 210 A for regular coal pitch, which is not in accordance with the invention Way is reacted with oxygen. The inven-

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proper isotropic carbons have values "g" below 0.2, preferably by 0.1.

The following examples 3 to 6 show that there is a crucial one There is an exchange of oxygen with the hydrocarbon distillate must be reacted so that the carbonized obtained Thread is isotropic. If less than the critical amount is used, the thread obtained becomes anisotropic. One more-

however, a fold increase in the amount converted yields / still one isotropic carbon. The excess oxygen has no adverse effect on that to be converted into isotropic carbon Hydrocarbon distillate.

Example 3.

1550g distillate of coal tar (creosote oil) were introduced into a closed reaction vessel and heated to 316 ⁰ C. and then for 4 hours at elevated pressure of 6.02 at blown with air or oxidized, with the distillate to 316 ° C. was held. The air was introduced into the coal tar distillate as a fine dispersion at the bottom of the reactor at a rate of 1.32 scf / kg / hr. From the oxygen balance it was found that the total amount of elemental oxygen consumed was about 42 g / kg of coal tar distillate. The oxidized distillate treated with air had the following distillation range according to ASTM test D246:

initial boiling point 231 ° C. cumulative distillate; %

to 270 ⁰ C. 4.8

to 300 ⁰ C. 12.2

to 315 ⁰ C. 16.5

up to 355 ° C. 53.6

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An aliquot of the air-treated distillate was removed from the reaction vessel removed and placed on a refractory tray in an electric kiln using gaseous nitrogen has been flushed through. The aliquot was heated in the kiln by gradual heating at a rate of 3 C./min up to 1000 ° C. and maintaining this temperature for 1 hour carbonized, the inert atmosphere of gaseous nitrogen being maintained in the kiln.

A sample was prepared from the carbonized aliquot and at 800x magnification under reflected polarized light with crossed Nicol prisms under a metallographic Examines microscope. The sample was identified as isotropic carbon because the intensity of the reflected polarized Light did not change with perpendicular rotation to the observation axis,

Example _4

1620 g of coal tar distillate (Creosot oil) were in a closed Given reaction vessel. The coal tar distillate was loud ASTM Test D246 the following distillation range:

initial boiling point of 22O ⁰ C. cumulatively / es distillate; %

to 235 ° C. 2.1

to 270 ⁰ C. 12.6

to 315 ⁰ C. 36.3

to 355 ° C. 80.9

Residue 19.2

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The coal tar distillate in the reaction vessel was heated to 316 ° C. heated and oxidized for 4 hours at atmospheric pressure with introduced air, the temperature of the distillate at 316 ° C. held became. The air was as a fine dispersion at the bottom of the Reactor at a rate of 0.90 scf / kg / hr into the Distillate introduced. From the oxygen balance it was found that a total of 30 g of elemental oxygen consumed e.ro_kg of distillate were murdered. An aliquot of the air-treated coal tar distillate According to the determination according to ASTM Test D246, it has the following distillation range:

initial boiling point 230 C. cumulative distillate; ^

to 270 ⁰ C. 6.7

up to 300 ° C. 16.1

to 315 ⁰ C. 19.8

to 355 ^° C. 59.4

This aliquot of air-treated coal tar distillate was placed in a refractory dish in a conventional electric furnace, which was then purged with nitrogen. The aliquot was in the kiln by gradual heating at a rate υοη 3 ⁰ C./min up to 1000 ⁰ C. and maintaining this temperature carbonized for 1 hour, with an inert atmosphere was maintained in the furnace gaseous nitrogen.

After carbonization of the air-treated coal tar distillate, a sample was prepared as above and in the specified Way examined under a metallographic microscope. The sample was identified as anisotropic carbon because the intensity of the reflected polarized light at

409837/0669

- 23 Rotation of the sample perpendicular to the observation axis changed.

Example 5

1450 g of the coal tar distillate described in Example 1 were placed in a closed reaction vessel, heated to 316 ° C. and oxidized with introduced air for 4 hours at a pressure of 6.02 at, the distillate being kept at 316 ^° C. The air was introduced into the coal tar distillate as a fine dispersion at the bottom of the reactor at a rate of 1.87 scf / kg / hr. From the oxygen balance it was found that a total of 57 g of elemental oxygen per kg of coal tar distillate had been consumed. The air-treated distillate had the following distillation range according to ASTH Test D-246:

initial boiling point 239 ⁰ C. cumulative distillate: %

to 27O ⁰ C. 5.2

to 300 ⁰ C. 10.4

up to 315 ⁰ C. ■ _ 14.2

up to 326 ° C. 21.5

up to 355 C. Start of decomposition

Softening point 124 ⁰ C. C / A

An aliquot of the air-treated distillate was removed from the reaction vessel and placed in a refractory tray in an electric furnace which was purged with gaseous nitrogen. The aliquot was carbonized by gradually heating at 3 ° C. / min to 1000 his ⁰ C. and maintaining this temperature for 1 hour, with an inert atmosphere was maintained in the furnace gaseous nitrogen.

A sample was produced from the carbonized aliquot and investigated in the manner described. The sample was said to be isotropic

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Carbon identified because of the intensity of the reflected polarized light did not change when rotating the sample perpendicular to the observation axis.

example 6_

1720 g of a return oil ('200X grade recycle oil' der Shell Oil Company) were placed in a closed reaction vessel given. The recycle oil was thermal cracking petroleum distillate obtained from crude oil has been produced. The return oil had the following distillation according to ASTM test D246 range:

initial boiling point

cumulative distillate ; ^

up to 270 ° C. up to 300 ° C. up to 315 ⁰ C. up to 355 ° C. up to 375 ⁰ C.

The oil in the reaction vessel was heated to 25O ⁰ C. and oxidised for 28 hours at atmospheric pressure with air introduced, wherein the oil was maintained at 250 ⁰ C.. The air was introduced into the recycle oil as a fine dispersion at the bottom of the reactor at a rate of 0.79 scf / kg / hr. From the oxygen balance it was found that a total of 80 g of elemental oxygen per kg of recycle oil had been consumed. An aliquot of the air-treated recycle oil was then removed from the reaction vessel (after cooling to room temperature); it was a pitch-like substance »The air-treated return oil had a pour point of 73 ° C and, according to ASTM test D247, the following distillation range:

409837/0669

267 ⁰ C 1, 3 31, 3 47, 3 78 9 87 5

initial boiling point 283 C.

cumulative distillate; % . '

up to 27O ⁰ C. -

to 300 ⁰ C. 8.1

to 315 ⁰ C. 19.2

to 355 ^° C. 30.3

up to 375Ϊ. 44.6

This aliquot of air-treated recycle oil was placed in a refractory tray in a conventional electric kiln, which was flushed with nitrogen. The aliquot was there by gradually heating at a rate of 3 ° C. / min up to 1000 C. and maintaining this temperature for 1 hour carbcnisiert, with an inert atmosphere in the kiln was maintained from gaseous nitrogen.

After carbonizing the aliquot of air-treated return oil a sample was prepared as above and examined under a metallographic microscope in the manner described. The sample was identified as isotropic carbon because the intensity of the reflected polarized light did not change when the sample was rotated perpendicular to the observation axis.

40 9 8 37/0669

Claims (2)

P at en t to sayings 1, - Process for the production of isotropic carbon filaments from hydrocarbons distillates, characterized in that one a) the distillate with one containing elemental oxygen Gas is reacted at a temperature of about 250-420 C. until at least 0.5 scf of elemental oxygen per 0.454 kg of distillate have reacted and the distillate is converted into a pitch-like substance, which after subsequent carbonization isotropic carbon supplies; b) a thread is formed from the oxidized hydrocarbon distillate; and c) .the thread in an inert atmosphere at temperatures above 800 C. carbonized. 2.- The method according to claim 1, characterized in that air is used as the elementary oxygen-containing gas. 3, - l / experienced according to claim 1 and 2, characterized in that daG the oxidized distillate is distilled to remove the low-boiling components before being formed into a thread. 4.- The method according to claim 1 to 3, characterized in that a) the distillate is reacted with an elemental oxygen containing gas at a temperature of about 250-420 ⁰ C., until at least 0.5 scf elemental oxygen per 0.454 kg of distillate have reacted, and converts the distillate in a pitch-like substance, which, after subsequent Carbonization provides isotropic carbon; 409837/0669 2357-77 b) the oxidized distillate is distilled until there is a (cube of air) Calibration point of about 80-200 ° C. Has; c) a thread from the oxidized carbon dioxide distillate shapes; and the thread in an inert atmosphere at temperatures above 8QO ⁰ C. carbonized. The patent attorney: 409837/0669 Blank page