DE1258532B - Process for the production of a binder for carbon electrodes - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

Clog

German KI .: 23 b -1/04

Number: 1258 532

File number: E 21421IV d / 23 b

Filing date: July 25, 1961

Open date: January 11, 1968

The invention relates to a method for producing a binder for carbon electrodes.

Carbon electrodes are usually made from burned coke, e.g. B. petroleum coke or coke of various types of coal manufactured. Since the coke naturally has no binding capacity, the parts have to be made by means of a Binder are bound.

In general, coal tar pitch or tar is used as a binder for amorphous and graphitized electrodes, Used blocks, cylinders, powders and other carbon products. The tar is powdered with or mixed with granulated petroleum coke or similar material; the mixture is pressed, extruded or shaped to give it the desired shape before firing begins. Coal tar is therefore particularly suitable because it has a high content of resinous insoluble in benzene Has substances that result in coke when carbonized at relatively low temperatures. Through this, that between the grains of the solid, carbonaceous, the bulk of the objects are formed Coke forms, this is cemented together to form a dense and very conductive product.

It has now been found that an aromatic petroleum residue can be successfully used as a binder for carbon electrodes in the following way. The procedure is that a aromatic petroleum residue obtained from being carried out at high temperature by means of steam Cracking of hydrocarbons has been recovered as long as it is heat treated above about 316 ° C about 70 weight percent of the aromatic petroleum residue is removed and then the softening point of the product with the aromatic petroleum residue is discontinued.

If one starts out from the petroleum residues of an aromatic tar, no binding agent suitable for electrodes is obtained in a one-step process. If, for example, the coking value and the proportion of the binder that is insoluble in benzene are high enough, the softening point is too high; if the softening point is within the correct range, the other values are too low. According to the invention, a binder intended for carbon electrodes is produced from a petroleum residue which is intended to imitate coal tar pitch binders; this is made in a two-step process. The first stage involves the application of high temperature to produce the benzene-insoluble resins or materials which are important in the binder and are considered to be the best binders for electrodes. A content method of making a binder
for carbon electrodes

Applicant:

Esso Research and Engineering Company,

Elizabeth, N. J. (V. St. A.)

Representative:

Dr. W. Beil, A. Hoeppener and Dr. H. J. Wolff,

Lawyers,

6230 Frankfurt-Höchst, Adelonstr. 58

Named as inventor:

Laurence F. King, Mooretown, Ontario;

Clellie T. Steele, Sarnia, Ontario (Canada)

Claimed priority:

V. St. v. America July 26, 1960 (45 295)

from about 30 percent by weight of benzene insolubles is desirable; the minimum content should be about 15 percent by weight of substances insoluble in benzene. Depending on the nature of the starting gas oil are obtained the aromatic tar in a yield of about 15 to 25 volume percent when gas oils up to approximately 40 to 45 ° / ₀ by weight conversion to C ₃ - are cracked and lighter hydrocarbons by means of steam. The aromatic tar has a bitumen content of about 12 to 25 percent by weight. These bitumen or resins contained in the pitch or binding agent, which are soluble in benzene but insoluble in petroleum ether, contribute to the adhesion.

The content of substances insoluble in quinoline is in the case of substances produced according to the invention from aromatic tars Binders or tars low. It is usually about 2 percent by weight, which is a good characteristic is. The quinoline-soluble substances in the binder are fusible and have after their Solidification a high bond strength. The substances soluble in quinoline are those which are insoluble in quinoline Superior to fabrics.

The second stage of destructive distillation involves fluxing or back mixing with a portion of the original aromatic tar. When examining tars, it is common to keep them up to around 360 ° C to distill and then determine the softening point of the residue. The ones at that temperature The distilling fraction should not exceed 6 percent by weight. This increases the proportion of light Product in the fluxed product to about 20 percent by weight based on 30 percent by weight flux oil, limited in the final mix. This is the only open

709 718/385

3 4

face limit for the aggregate material that z. B. in the form of a destructive distillation or can be used .. mild coking with recovery of a volatile The pitch binder material prepared according to the invention, which can be withdrawn as the top product and then suitable for the production of prefired or condensed, and a high-boiling Söderberg electrodes. It is particularly useful for polymeric constituent that remains and is essentially insoluble in the manufacture of electrodes for which aluminum-benzene is used. Then the production, but its use is not, heat-treated aromatic tar is fluxed or mixed back with a lower-boiling liquid until the desired softening point is reached as the starting product, an aromatic tar. A portion of the aromatic tar used as a starting product or bottom product in the steam reforming process can be used as the high-boiling residue flux agent. Gas oil with the formation of olefins, diolefins, aro- If the heat treatment occurs under excess pressure through matic liquid hydrocarbons. guided, as is the case with viscosity breaking or heat-subsequent physical treatment, so condensed and polymeric two aromatic residue tars, the 15 siert a part of the light material as a result of the longer contact time in the process according to the invention as a starting point. From the technical service products can be used, listed: From the standpoint, the specific gravity according to the invention is carried out at 15.5 ° C. 1.089 1.110 process preferably by heat treatment and flash point COC in ⁰ C 149 160 flash evaporation. It can be used with a moderate viscosity / 210 Seybold Su ... 95 213 ²⁰ pressure of about 3.5 to 105 atmospheres. Carbon, percent by weight .... 89.5 90.4 ^A heat cracking heating coil with a full-heat hydrogen drum, percent by weight .. 7.2 6.8 drum can, for heat treatment aromatic

H / C atomic ratio 0.96 0.90 ^tar can be used. The products are flash

Sulfur, weight percent 1.9 2.0 evaporated and the residues of the light top ash content, weight percent. 0.003 0.01 * ⁵ products won. It becomes a sufficient amount

. Bitumen, weight percent. 17 22 of ^the light material removed to remove a residue

λ οτΛί T-I + ίι + · to win product with a softening point,

AbiM-Destüiation ^ _{6 er for the} inventive petroleum tar binding

_{The initial boiling point is} 270 299 ^ 1 ° C.

JL ' ⁰ "■ · ■ ■ · /; ^ Z IZL 30 An embodiment of destructive distillation

vn consists in taking a 700-cm ³ sample of the aromatic

. · _; Jr ⁵ ^ f tar from the steam cracking in a 2-1 distillation

/ ofi-i α «« apparatus with a round bottom made of stainless steel

Tr J. ⁰ ; rr | 7 * 1 bring. This still stands in one

1 ⁵⁰ ° .384 AU ₃₅ H _e j _CGU fäß _{un (jj st} jnit _e i tightly sealing _nem

According to the invention, aromatic residue lids are made of difficult-to-melt glass, the four conical teas used, the corresponding values of which has between standard shaped openings, closed, The two rows listed lie or something. Two thermocouples run through these openings deviate from it. (for one steam and vessel temperatures), one with

The steam cracking process is known. It consists of 40 mercury-sealed agitators, a distillate

in that one. a gas oil with an initial boiling outlet and an arm dedicated to the flux,

point of about 204 to 274 ° C and a final boiling point during the fluxing agent treatment. the under

point of about 399 to 440 ⁰ C at a starting temperature isothermal conditions should be carried out,

temperature on the heating coil between about 649 and one of the thermocouples replaced. 788 ° C in the presence of about 60 to 85 mole percent 45 The steam temperature in the still was

Steam cracks and this immediately with an oil, to about 274 to 377 ° C and the vessel temperature

that boils between about 260 and 357 ° C, kept at between about 343 to 454 ° C. The warmth was through

quenched around 282 and 293 ° C. The gas oil has been fed to a gas heater. "..

specific gravity of 0.8735 and a molecular The destructive distillation took place during about

weight of about 290 and has about 11.3 weight 50 25 to 60 minutes at a speed of

percent of compounds with aromatic rings about 5 to 30 cm ^s / minute until the desired return

and about 32.2 percent by weight of compounds with stand product was reached. This was made possible by the

naphthenic rings. Percentage of the top product discharged

The. gaseous products, consisting of hydrogen, trolled. Then the necessary amount of fluxing agent oil, saturated hydrocarbons, olefins and diols - which in this case consist of a part of the aromatic tar fines - are withdrawn overhead; and such as aromatic gasoline with a boiling range between 15 minutes was further heated and stirred. The 38 and 238 ⁰ C and a higher boiling aromatic heating mantle, which surrounded the lid of the still fraction with a boiling range between about 188 60 , was removed shortly before the flux treatment and 299 ° C, which was in the quenching zone of the steam to prevent that further overhead product can be recycled to the cracking plant, separated over. Can be used as a liquid flux agent. Residual aromatic tar is obtained in: (a) the aromatic tar feed in the amount of about 15 to 25 percent by volume of the specifically described type, (b) the fractionation based on the feed. 65 residues from catalytic cracking with

The aromatic tar is .invention as an initial boiling point of about 232 ° C and a

Starting material used and boiling to about 399 to 50% of the material of about 435 ° C

482 ⁰ C heated. Such a heat treatment is carried out or (c) any other high-boiling, liquid re-

Standing oil or distillate, which ^{can be distilled off up to 360 0} C only to 20%.

In one embodiment, a destructive distillation using a stainless Steel vessel and the corresponding process resulted in the following data:

Table I.

Volume percentage Time, Steam temperature, Head product Minutes ⁰ C Initial boiling point 0.0 285 5 5.5 297 10 12.0 307 15th • 17.2 313 20th 23.7 320 25th 28.0 329 30th 32.7 334 35 37.6 340 40 43.0 351 45 48.2 352 50 53.3 352.4 End point ■ - 352.4

Weight percent residue (based on still feed) = 36.2. Weight percent yield (based on the charge in the still) = 96.5.
Residue coking value = 64.3.

There were mixed, for example, about 72.8 parts by weight of the residue of Table I with 27.2 parts by weight of fluxing agent (aromatic Teerbeschickung) and heated for about 15 minutes to about 427 ⁰ C. The resulting tar had a softening point of about 103 ^° C., a coking value of about 52.7 percent by weight and contained 26.4 percent by weight of components insoluble in benzene.

In another example, the residue was about 37.6 percent by weight. 78.4 parts by weight of this residue were heated for 15 minutes at about 427 ⁰ C after about 21.6 parts by weight of fluxing agent had been added. The tar obtained in this way had a softening point of about 113 ^° C., a coking value of about 54.5 parts by weight and contained about 32.3 percent by weight of components insoluble in benzene.

When using flux treatment, the actual rate of distillation does not appear to be critical. But what is essential is the end point. In one experiment, in which the aromatic feed was heated to a pot temperature of about 479 ⁰ C and the distillation time was about 45 minutes, the residue amounted to 27.9 percent by weight, and when using 37.3 weight percent quenching to let the Do not mix residue to a homogeneous product. In another experiment, in which the vessel temperature was about 451 ° C. and the distillation time was about 30 minutes, the residue obtained was 31.2 percent by weight. This residue could be blended into a tar binder using 36 weight percent quench oil. The product had a softening point of about 122 ^° C., a coking value of about 55 percent by weight and contained about 32.5 percent by weight of substances insoluble in benzene.

The coking value of the product is the non-volatilized, expressed in percent by weight of residue which is obtained when a sample is in a melting pot, and heated for about 2.5 hours at 549 ⁰ C.

Part of the aromatic tar feed was used as a flux agent. During the whole Process was stirred. Less than about 70 percent by weight should be used during destructive distillation the aromatic tar can be drawn off overhead; because it turned out that if more than about 70 percent by weight of the aromatic tar is withdrawn, the residue no longer with success to a homogeneous product and good binding agent by means of a flux agent or mixing can be processed.

The data listed in the following Table II have been obtained at a destructive distillation of the aromatic Teerbeschickung at a steam temperature of about 274-377 ⁰ C and a pot temperature 343-454 ⁰ C to give the corresponding residues. The latter are given in percent by weight (based on the aromatic tar used as the starting product). The heating times were about 30 to 60 minutes. Also indicated are the mixtures treated with a flux agent which contain the distillation residues treated with the aromatic tar feed or the starting product. The physical data show that the mixtures come very close to the usual regulations for a coal tar intended for use as an electrode binder. The overall yield of pitch as a binder for electrodes, based on the aromatic tar feed, was about 43.3 percent by weight.

Table II

Flux treatment

properties

of a coal

tar pitch that is

as a binder

has proven itself

Yield of residue (based on tar feed), percent by weight

Mixtures: composition in percent by weight

Residue

Aromatic tar flow

Physical data

Softening point, ⁰ C

Coking value, percent by weight

Ingredients insoluble in benzene, percent by weight

34.7 33.3 32.1 34.8 68.7
31.3 68.6
31.4 67.7
32.3 68.5
31.5 93
50
23 102
53
24 120
57
36 98
53
24

33.2

68.2
31.8

109
55
30th

83
55
30th

Pitch binders made from heat-treated aromatic tars according to the invention, have the following properties:

Table III

Softening point, ° C.,

Carbon, weight percent

Hydrogen, weight percent

C / H atomic ratio

Coking value, ° / ₀

Components insoluble in benzene,

Weight percent

Sulfur,%

Ash content,%

108

91.9
5.9
1.31

53.9

16.5
1.7
0.08

102

92.3 6.1 1.38

52.6

25.6 1.5 0.03

IO

The binder listed under B was used to produce an electrode. In general . the petroleum coke is sieved and various particle sizes are used. The coarse-grained part of the burnt coke (it can be a petroleum coke) is mixed with the heated binder and then the other, finer-grained coke parts are added. The mixture is formed under pressure and for a longer time, up to about 24 hours to about 1000 ⁰ C heated, the temperature being, kept at 1000 ° C for only about 1 hour to char to the binder or to coke. An electrode was then made using Binder. This electrode met the requirements for minimum compressive strength and specific electrical resistance. Of course, other methods of manufacturing the electrodes can also be used.

Claims (4)

Patent claims: 1. A method for producing a binder for carbon electrodes, characterized in that that an aromatic petroleum residue, which from the at high temperature by means of steam carried out cracking of hydrocarbons has been recovered for so long about 316 ° C is heat treated to about 70 weight percent of the aromatic petroleum residue are removed and then the softening point of the product with the aromatic petroleum residue is set. 2. The method according to claim 1, characterized in that that the aromatic petroleum residue in an amount of about 30 to 35 percent by weight is admixed to 70 to 65 percent by weight of the heat treated residue. 3. The method according to claim 1 and 2, characterized in that the residue is heated for about 1 hour to 343 to 454 ° C (liquid temperature) until about 69% of the residue is removed as top product, 4. The method according to claim 1, characterized in that the heat treatment in the form of a destructive distillation is carried out essentially at atmospheric pressure. Considered publications: Abraham — Brühl, Asphalt and allied Fabrics, 1939, p. 469/470. Legacy Patents Considered:
German Patent No. 1102 030. A priority document was displayed when the registration was announced. 709 718/385 12.67 © Bundesdruckerei Berlin