US3248303A - Activatable coke from carbonaceous residues - Google Patents

Description

United States Patent F 3,248,303 ACTIVATABLE COKE FROM CARBONACEOUS RESIDUES Ernest G. Buying, Rocky River, Ohio, assignor to Union Patented Apr. 26, 1966 Neither the kind of carbonaceous residue nor its origin is critical in the instant process. The process as taught herein can be applied to any liquid or solid tarry or pitch-like material. The applicability of this process arhide Corporation, a corporation of New York 5 extends even to p h l too high anfirvon or ash N0 Drawing. Filed May 1, 1964, gen No: 364,270 content to find utilization in the carbon industry, for

5 Claims (CL 2 1 g example, hardwood pitch.

When the carbonaceous material is in the liquid state This application is a continuation-in-part of my preit can be mixed directly with the carbonizing agent and vious application, Serial No. 736,972, filed May 22, 1958, heated slowly up to the requisite temperature or the now abandoned. heating can be temporarily interrupted as soon as the This invention relates to a process for preparing material becomes solid, the solid material then subjected activatable coke from carbonaceous residues such as those to a size reduction operation, and the heating then conobtained from wood, coal, and petroleum. tinued. Both procedures have been followed with sub- The use of tar or pitch as a binder is well known in stantially the same result. the carbon industry. Tarry and pitch-like .materials, On the other hand, when carbonaceous material is 21 however, have hitherto not been seriously considered as solid at room temperature, the material should be com= a source of base carbon since the material produced .minuted or crushed prior to admixing with the carboniztherefrom is too dense and lacks the requisitepore strucing agent. Preferably the solid material should be milled ture. Previous attempts to impart a cellular structure to a flour passing through a 100 mesh screen. to coke made from tars or pitches by adding thereto In either event, the resulting admixture is slowly heated, carbonizing or dispersing agents have not been comusually in the absence of air, to a temperature in the mercially practical, in general, because of the low yield range from about 450 C. to about 500 C. so as to expel of activate-d product obtainable therefrom and because the volatile constituents and carbonize the residue. of the processing difliculties normally encountered during 25 The thus produced activatable coke can then be activation in such instances. crushed to the desired particle size and activated, or it can The recent development of new unit processes in the be pulverized, formed into pellets using a suitable binder, chemical industry such as the hydrogenation of coal, for and then conventionally activated with limestone or an example, has increased the availability of tarry and pitchoxidizing gas such as steam or flue gas. like y-p materials? In y Of these Processes The following examples illustrate the present invention. the by-product materials are of such uncertain composition and have such unpredictable properties as to render Example 1 these materials unsuitable as binders for formed carbon products Two 100 gram portions of powdered coal depolyrner1- It is an object of the present invention to provide a Zation P Q Were admlXed separately f and method for producing activatable coke from liquid and gram portions of concentrated sulfur1c ac1d diluted with solid carbonaceous residues yielding activated carbon 70 aflcl 56 grams W The' tWO mlXtllfeS W then 'having properties comparable to those of activated carbon CarhOmZed y heatlhg Slowly hours) 1h covfired obtained from coconut charcoal and petroleum acid crucibles At this POlIlt, ihe Coke Ylfilds md k 41 amounted to 94.4 and ..97.6 grams and contained 87.6 It is another object to provide methods for producing and 86.0 percent fixed carbon at 950 C. Both cokes activatable coke from liquid and solid carbonaceous resiwere th h d through 100 h d 20 gram dues employing carbonizing gents. tions of each were mixed with 175 and 172 grams of 20 Still Other objects will readily Preseht themselves to the to 65 mesh limestone (an amount of limestone equivalent skilled artisan upon reference to the ensuing specification 45 to ten times the fixed Carbon content f the cokes), and tha claim? placed in crucibles packed in coke and heated to 950 C. The foregomg qblects i achleved by provldmg to decompose the limestone and activate the carbon with bonaceplis mammal addmg therito sulfur'coptalmpg the evolved carbon dioxide. The resulting carbons were carbotmzmtg agents; $3 25 f gi g gfii i f i g then separated from the lime with a 100 mesh screen and .33258 3 :2 to gi the Volatiles and tested. The adsorptivecapacity of the carbon was deterbOm-Ze the residue. mined by exposing weighed samples in a desiccator to Carbonizing agents suitable in the practice of this in- Carbon t6tfach10f1d P Values reported In vention include sulfur, sulfuric acid, potassium sulfide, Table I show the Weight percentage adsorbed at saturapotassium thiocyanate, and the like. tion or constant weight, based on the true carbon content.

TABLE I 450 Coke Activation Data Acti- Overall C Cl Yield, AD 1 F0, L/FC 3 vation Yield, sat, AD Percent Percent Yield, Percent; Percent Percent ii o 2523 5 2335251.-. 59.5 .690 88.0 10 37.7 22.4 10.9 1.28

l Apparent Density. 2 Fixed Carbon at 950 C.

3 Limestone to fixed carbon ratio.

It should be noted in Table I that when the pitch is carbonized with sulfuric acid, its coke is readily activated and the resulting carbon adsorbs from 68 to 84 percent of its weight of carbon tetrachloride. In this connection, it is well to note that the activatability of the coke and the coke yield both increase with the concentration of the acid used. This is shown in Table I in the case of coke made with 30 and 90 percent sulfuric acid. On the other hand, when the surfuric acid is eliminated from the procedure, the resulting carbon only adsorbs 11 percent carbon tetrachloride, its density is much higher and the yield is lower.

4 Example 4 The procedure of Example 1 was repeated with hardwood pitch, except the 450 C. coke was crushed through 200 mesh, formed into pellets with more pitch as binder, and then activated with limestone at an 8/ l fixed carbon ratio as indicated in Table IV, below.

TABLE IV Pitch mix: Hardwood pitch Pitch, parts 100 10 H 80 parts 100 Water, parts 23 Coked at 450 C.:

Example 2 Yield, percent 74.5 The same general procedure as in Example 1 was fol- Apparent density (10-14 mesh) .458 lowed, except that 20, 30, 40 or 60 grams of powdered Coke mixed with wood pitch and pelleted: sulfur was mixed with 100 grams of powdered pitch Coke, parts 100 in place of the sulfuric acid. These admixtures were Pitch, parts 40 slowly heated, as before, to 450 C. to expel the volatile Oil, parts l and carbonize the residue, then crushed through 100 Mixer yield (pitch basis), percent 107.3 mesh and activated with a 10/1 limestone-fixed carbon 20 Apparent density (green pellets) .649 ratio. The experimental results are compiled in Table Apparent density (calcined pellets) Fused II below. Fixed carbon, percent 68.0

TABLE II 450 Coke Activation Data Acti- O verall C C] Yield, AD no, L/FC vation Yield, Sat., AD Percent Percent Yield, Percent Percent Percent 1 Apparent Density. 2 Fixed Carbon at 950 C. 3 Limestone to fixed carbon ratio.

These results readily show the advantage of the added Activation of pellets: sulfur. For nearly the same product yield, the activity 40 Lime/fixed carbon 8/1 of the carbon was increased from 42.5 to 83.5 percent Yield, percent 27.0 by the simple expedient of raising the sulfur from to Overall yield, percent 29.0 60 parts per 100 parts of pitch. Activity, percent 97.1 E l 3 Retentivity, percent 52,1 mm? 8 Apparent density 0.322

In this case, the powdered pitch was mixed with 5, 10, 20 and 40 parts of pulverized potassium sulfide per 100 parts of pitch, carbonized and crushed as before, but then divided into two portions. One portion was activated directly with an 8/1 limestone-fixed carbon ratio and acid-washed after activation, while the other portion was acid Washed before activating with an 8/1 limestone-fixed carbon ratio. The results in Table III show that it is beneficial to remove the salt before activation, but that improved results are possible in either case, especially when compared with pitch carbonized witout an added chemical.

In Table IV, and in Table V below the term Activity" denotes the percent CCl adsorbed by a 10 cm. layer of dry carbon at saturation and C. from pure dry air saturated with CCl vapor at 0 C. and the term 0 Retentivity denotes the percent CCl retained by the same sample after pure dry air is passed through the saturated sample for exactly six hours at a linear velocity of 500 cm./min.

The best pelleted carbon made from pitch has charac- 5 teristics which compare favorably with carbon made from petroleum acid sludge and cocoanut material. This comparison is presented in Table V below.

TABLE III 450 Coke Activation Data Actl- O verall 0 C1 Yield, AD 1 liC. L/FC 3 vation Yield, Sat, AD 1 Percent Percent Yield, Percent Percent Percent Pitch Garbonized With- 8 26. 4 21. 7 36. 2 .825 70.0 .990 s3.2{ 2 1 070 8 20. .729 10% K25 w-s 20.0 21.0 09.1 .785

w as it; 3312 a K28 wi 23:? 33 2313 :23?

1 Apparent Density.

2 Fixed Carbon at 950 C.

3 Limestone to fixed carbon ratio. W=Coke acid washed before activation.

11 Yield from original pitch. b Yield from coke. Yield from charcoal.

In additional examples of the practice of the invention, co ke samples made in accordance with Example 1, 2 and 4 were activated with steam to give activated carbon having substantially the same properties as indicated in the tables. Thus it can be said that the precise method of activation is not critical to the present process.

Example 5 Portions of refined coal tar (1500 grams) and settled wood tar (2100 grams) were placed in glass beaikers and mixed with equal amounts by weight of concentrated sulfuric acid. The resulting mixtures were heated to and held at about 150 C. in a ventilated electric oven overnight (approximately 16 hours). This procedure yielded hard, porous, solid residues of black color in both instances.

The solid residues were then rough crushed and packed individually in covered carbon crucibles. The crucibles, in turn, were packed in coke in an alloy box and heated to about 500 C. in an electric mufile furnace.

The resulting activatable residues were then crushed and sized to 6-14 mesh. Portions of the sized acti-vatalble residues (about 50 to 60 grams each) were then acti- As is readily apparent from the results reported in Table VI good yields of activatable coke can be obtained in the aforedescribed manner.

Example 6 Portions of refined coal tar (213 grams) and settled Wood tar (200 grams) were placed in glass beakers and mixed with equal amounts by weight of concentrated sulfuric acid. The beakers containing the admixtures were then covered with sheet asbestos and placed in an electric pot furnace.

The mixtures were then heated to about 450 C. in about 2 hours and were stirred to prevent foaming until solidification. solidification was observed to take place at about 320 C. with the coal tar and at about 188 C. with the wood tar.

When the foregoing mixtures reached about 450 C., they were removed from the furnace, cooled rapidly and weighed.

A portion (about 50 grams) of each thus obtained activatable coke was then transferred to a carbon crucible which was then packed in coke and heated to about 950 C. in order to determine the fixed carbon content of the activatable coke.

The experimental results, based on 100 parts by weight of original tar are reported in Table VII below.

TABLE VII Re lined Coal Tar Settled Wood Tar The foregoing results show that at 950 C. the fixed vated in an atmosphere of steam and nitrogen for about carbon yields for the coal tar and the wood tar were 87 1 to 2.5 hours at about 950 C. The activator was a and 56 parts by weight, respectively. These yields comcy-lindrical alloy vessel equipped with lifting vanes, and pare very well with those reported for coal tar and wood a steam preheater. During activation the activator was tar in Table VI, i.e., 84.5 and 55.4 parts by weight, respecrotated at about 10 r.-p.m. and was purged with nitrogen tively, and indicate that in the case of liquid tars it is during the heat-up and the cooling. immaterial whether or not the heating step is interrupted The data from this example are summarized in Table as soon as the tars solidity and whether or not the solidi- VI below. 1 fied material is subjected to a size reduction before the TABLE VI Refined Coal Tar Settled Wood Tar Liquid tar, parts by weight 100 Sulfuric acid, conc., parts by weig 100 100 Heated 16 hrs. at 0. parts by weight 147. 3 100 Calcined to 500 art 92.5 64.8 Sized 6-14 mesh, percent yield 62. 6 71. 5 Sized 0-14 mesh, parts by weigh 57. 8 46. 3 Properties of Activatable Coke:

Apparent density (6-14 mesh) 552 .621 Fixed carbon (950 C.), percent..- 91. a 85. 5 Fixed carbon (950 0.), parts by weight 84. 5 55. 4

Activated in steam at 950 0.:

'1in1e,l1ours 1 1% 2 1 2 2% Activation yield, percent of 500 coke 67.1 51.0 33.9 67. 5 40.0 32.4 Overall-yield based on tar, parts by weight. 38.8 29.8 19.6 31.2 18.5 15.0 Overall yield based on tar, but

excluding fines loss, parts by weight 62.0 47.7 31.4 43.7 25.9 21.0 Properties of activated carbon:

Activity, percent 0014 adsorbed 34. 4 (l0. 8 90.8 24.8 64. 5 75. 7 Rctentivity, percent CCl; re-

tained Z 19.1 29.4 31.9 11.3 28.5 25.6 Apparent density, g./ml 524 406 327 .584 .389 350 1 The percent CClr adsorbed by a 10 cm. layer of dry carbon at saturation and 25 C. from dry air is passed through the sample for exactly six hours at a linear velocity of 500 cm./min.

heating is continued to a temperature from about 450 C. to about 500 C.

Example 7 About 100 parts by weight each of 30 medium coal tar The exact mechanism.whereby the indicated results are obtained is not known exactly. It is quite evident, however, that the added carbonizing agents increase the porosity and internal surface of the coke.

pitch, 15 soft coal tar pitch and hardwood pitch were I claim: admixed Wlth P 20 P by Weight potasslufn 1. A process for making an activatable coke which l- Each resultfng admlxmre was w Into 2 comprises providing a tarry, pitch-like, carbonaceous resiahqlylots Each ahqlfot was then,c-ntamed m a One'hter due; mixing therewith a sulfur-containing carbonizing beaker and Placed an electnc Pot furnace at room agent selected from the group consisting of sulfur, sulfuric g f b acid, potassium thiocyanate, and potassium sulfide; and h g a lquobt of 33 g h a 8 admixtures 2 i slowly heating the thus-formed mixture to a temperature F a f h i 2 Ours h er of at least about 450 C. to about 500 C. so as to expel 9 0 e We a mlxtpres gate to the volatiles contained therein and to carbonize the about 450 C. in about 2 hours. During heating the conresidue tents of each beaker was stirred continuously so as to 2 f t bl k h prevent frothing. Heating was terminating as soon as Proms? ma mg an a(,:lva a e co e W the pitch-potassium disulfide mixture reached the desired COIPPHSeS provldfng a sohdqtarry i carbpnaceous temperature. The beakers containing the admixture were resldue; Pulvenzlng resume; mlxlng therewith a then removed from the furnace and cooled to room temfuf-eontall'llng earbonlllng agent Selected from the group perature. consisting of sulfur, sulfuric acid, potassium thiocyanate The cooled residue in each beaker was crushed to a and potassium sulfide; and slowly heating the thus-formed e Size and activated y eollventioniil methods mixture to a temperature of at least about 450 C. to hzlgg hmesttonte 2 T l to abmt a f fijfed about 500 C. so as to expel the volatiles contained therecar on con en 0 eac a quot was eterm1ne y eating in and to Carbonize the residue.

a small portion of the sized material to about 950 C. 1 h in a carbon capsule packed in coke. The particle size The P P ,accordaflce w c 2 W ercm of the crushed residue and the limestone-to-fixed canbon F carbomzmg agent 15 Sulfunc acld Present an amount ratio employed in each instance is indicated in Table VIII 111 range q about to about 100 Percent y below. weight of the residue.

Thereafter the resulting carbon product and the lime- 30 4. The process in accordance with claim 2 wherein stone were separated by screening and acid washing. The the carbonizing agent is sulfur, present in an amount in adsorpiive p y Q the Obtained eallbon Product Was the range from about 20 to about 60 percent by weight determined by exposing weighed samples of the product f the residue to Cali-hon tetrachlonde Vapors over. hquld .carbon tetra' 5. The process in accordance with claim 2 wherein chloride, at room temperature and in a' desiccator. The lfid maximum amount of carbon tetrachloride vapors absorbed the carbcfmzmg agent 15 potasslum Su present m an b h product was determined by Weighing Samples f amount in the range from about 5 to about 40 percent the carbon product before and after the absorption. by weight of th r s d TABLE VIII 30 Medium Coal 15 Soft Cool Hardwood Pitch Tar Pitch Tar Pitch Pitch, parts by weight 100 100 100 100 100 100 K28, parts by weight 20 20 2O 20 20 20 Heating Yield, pts/IOI) pts. pitch 101. 3 92.9 81.2 77. 8 90. 5 75. 6 Fixed carbon, weight percent 77, 1 83, 3 76. 0 83. 1 65. 2 87. 7 Mesh size of product before activation 100 100 4-10 4-1 0 4-1U Limestone, fixed carbon ratio, by weight 8/1 8/1 7/1 Activation yield after screen separation, pts

100 pts. pitch 24.1 39.1 34.3 3.5 13-2 6- Ash, weight percent..." ND. ND. 95. 0 28. 1 62.5 42. 7 C014 saturation, percent 2. 4 6. 5 2. 2 6. 6 2. 7 16. 6 Activation yield after acid washing, pts./100

pts. pitch 10, 0 13. 1 5. 1 1. 8 6. G 1 1 CCl; saturation, percent 36, 3 52. 2 10. 7 37. 8 6. 1 1

N OTE.-N.D. not determined.

The data in the foregoing table amply illustrate the References Cited y the Examiner necessity of heating the carbonaceous material to a UNITED STATES PATENTS g g i i g; 1,756,234 4/1930 Becker 202-34 e erbaciviyan a ower as con en in e na pro uc 1,813,341 7/1931 Cunningham 202 34 are 0 tamed- 2,201,050 5/1940 Oberle 252422 It was also observed that the carbonaceous particles 2,234,769 3/1941 Mccunoch 2()2 34 that were heated only to 400 C. in the manufacturing 2,314,641 3/1943 W lf 20234 process tended to soften and fuse with the limestone during 2,377,063 5/ 1945 Adler 252425 activation, whereas the carbon particles that were heated 2,585,454 2/1952 Gainson 252422 to 450 C. under the same conditions did not. This is 2,725,360 11/1955 LeWlS et 2,829,115 4/1958 Bushong et a1 202-34 illustrated by the significant difference in the ash content of the 400 and 450 C. cokes after screening to remove the lime.

MORRIS O. WOLK, Primary Examiner.

Claims (1)

1. A PROCESS FOR MAKING AN ACTIVATABLE COKE WHICH COMPRISES PROVIDING A TARRY, PITCH-LIKE, CARBONACEOUS RESIDUE; MIXING THEREWITH A SULFUR-CONTAINING CARBONIZING AGENT SELECTED FROM THE GROUP CONSISTING OF SULFUR, SULFURIC ACID, POTASSIUM THIOCYANATE, AND POTASSIUM SULFIDE; AND SLOWLY HEATING THE THUS-FORMED MIXTURE TO A TEMPERATURE OF AT LEAST ABOUT 450*C. TO ABOUT 500*C. SO AS TO EXPEL THE VOLATILES CONTAINED THEREIN AND TO CARBONIZE THE RESIDUE.