DE2157096A1 - Improved process for making activated carbon - Google Patents

Description

656

Applicant: The Standard Oil Company, Midland Building, Cleveland, Ohio 44115, USA

Improved process for making activated carbon

The present invention relates to an improved process for the production of activated carbon from a shaped carbonized one Mixture of coal and an acid sludge. In particular, it relates to a process for the production of activated carbon high activity and in high yields due to the fact that the volatile constituents during the carbonization of the shaped Coal particles are effectively removed, the formed carbon products by mixing, molding and deacidifying finely divided coal products obtained with petroleum acid sludge.

In the parallel running patent application P 19 58 289.9 from 11/20/1969 »the content of which is referred to in the present description is a process for the production of im general granulatfö'rmigen coal products described, wherein

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the particle diameter ranges from about 5 to about 12 mm and the roundness of the particles is in the range of 0.5 to 1.0. This process consists in the fact that the finely divided Carbon product such as petroleum coke, acid coke, charcoal, Bituminous coal, lignite, soot, charred plant materials and the like having a particle size of less than 42 Tyler meshes are mixed with a mineral oleic acid sludge and forms therefrom moldings, these moldings harden by a heat treatment, the hardened moldings by further Heat treatment deacidified the granules by heating them to an even higher temperature, removing essentially all of them volatile constituents are carbonized and finally activated by known methods. The present invention relates primarily on -Io penultimate of the above mentioned stages; it concerns the careful and rapid removal of the volatiles formed during charring Components from the total amount of granular coal products. According to the invention, this can be achieved by carrying out the carbonization in one of several ways Use of various devices is carried out. E.g. the finely divided or granular carbon products are spread in a thin layer on a tray-shaped bottom and in a Circulating air oven can be carbonized with effective air circulation, thereby removing the carbon particles from the mass

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any volatile components formed are quickly removed. On the other hand, the granules can be in an oven with multiple hearths, as described, for example, in U.S. Patent No. 3,153,633. Such devices are equipped with a gas vent above each hearth so that any volatilized in each hearth area Components can be quickly blown out of the oven and thus only in minimal contact with the colile particles come. An example of such a multi-burner oven used to perform the last two stages of the The method according to the invention can be used, is shown in the accompanying drawings.

Acid slurries as used in the process according to the invention v / ground, fall in the manufacture of alkylate detergents, alcohol processing and various petroleum refining operations, in particular when treating gasoline with sulfuric acid, the so-called white oils leading treatment of phenol extracted oils with fuming sulfuric acid (or sulfur trioxide) and in the production of lubricating oils, mineral sealing oils and higher-boiling petroleum distillates. The alkylation of benzene or toluene with the tetramer of propylene and the like to make alkylate detergents makes a usable sludge. Others useful

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Sludge is produced in the alkylation of benzene with ethylene to produce ethylbenzene or in the alkylation of benzene with propylene to produce curaen. The alkylation of aliphatic compounds such as isobutane or n-butane with butenes to produce mixed products with a high octane number in conventional petroleum refining processes generally does not result in an "acid sludge" since the alkylating acid used generally forms a single liquid phase which is formed on standing in not split into two phases. In the literature, the used alkylating acid is often incorrectly referred to as "sludge", especially in those cases where the real problem is its decomposition to recover the acid (see The Oil & Gas Journal of February 9, 1950, p. 80, and of February 18, 1954, p. 102).

In the details in the parallel patent application P 19 58 289.9 described method is a particulate carbon product such as petroleum coke, acid coke, charcoal, Bituminous coal, lignite, carbon black, or charred vegetable products with a particle size of less than 42 TyIer-Masehen the following Process stages are subjected to:

(1) The carbon product is mixed with a mineral acid sludge, which contains at least 5 Gev.-ί'ό hydrocarbon products, in a ratio of 5: 1 to 1: 5 Gowicivtsteile carbon

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material mixed into acid sludge and granules mixed in a folding or rolling mixing action at a temperature in the range from -18 to + 150 ° C;

(2) the product is then dried and cured at a temperature in the range of 82 to 150 ° C;

(3) the cured product is then neutralized at a temperature in the range of 150 to 300 ⁰ C;

(4) the deacidified particles are sintered at a temperature in the range of about 300 to 815 ° C to form sintered ones Particles carbonized;

(5) Finally, these sintered particles are activated by that they are exposed to a mild oxidizing gas such as water vapor or CO2 at a temperature in the range of be brought into contact above 815 ° C.

As mentioned above, the present process is primarily concerned with step (4). A preferred embodiment of the present method is that the steps (2) and (3) are carried out separately in order to ensure the formation of a particulate activated carbon product with the desired high Ensure density.

The raw particles obtained in step (1) contain a considerable amount of volatile constituents. A thermogravimetry see analysis shows that the volatiles

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make up about 40 % of the weight of the raw particles. These volatiles are removed in the drying, deacidifying and charring stages of the present process. It has been found that in order to form a high quality activated carbon product it is necessary to properly remove these volatile constituents, otherwise a contaminated carbon product of lower density and reduced activity is obtained.

For example, if the above steps (2) and (3) are combined and carried out as one step, a product becomes relatively smaller Density formed, which then only results in an activated carbon product with a low density. Possibly the reason for that lower density of the products obtained by direct heating to a temperature in the range of 315 ° C with summary of the Steps (2) and (3) are obtained to see that the volatiles are driven off the particles too quickly and thereby a "puffed rice" effect occurs, which creates relatively large internal voids in the particles remain during the remainder of the process so that ultimately a relatively low density activated carbon product is obtained will. However, it is possible to carry out steps (2) and (3) in the same rotary dryer in countercurrent by that in the dryer a temperature gradient of about 95 ° C in the input area to about 345 ° C in the discharge area of the

rocking device -7-

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and parallel solid streams are used and here the volatile constituents should be stripped off as soon as possible after their discharge in each stage of the dryer.

It has also been found that in step (4) the volatile constituents practically just as quickly up close all particles must be removed as they are formed. For example, it was found that when you look at the a proportion of the carbon particles during carbonization stage formed volatile constituents with other amounts of particles upstream or downstream of the material in the carbonation device lets come into contact even for a relatively short time, certain amounts of the volatile constituents possibly condense in and on the particles and thus cause contamination of the particles. Such polluted particles require long treatment times for activation and eventually have inferior activity and can be obtained in only low yields, which is possibly due to Carbon or COp losses during the necessary long periods Activation time.

If, however, according to the invention, the volatile constituents formed during the carbonization stage (4) are quickly removed from the areas in which the particles are carbonized, a product is obtained which, with the formation of a relatively active carbon product, easily within a short _o

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Periods of time and with good yields.

The mineral acid slurries which can be used in the process according to the invention are acid sludges that contain a considerable proportion of hydrocarbon products. Examples for such sludges are those that are used in the manufacture of mineral sealing oils, lubricating oils, alcohol washing oils or alkylate detergents are obtained. Another acid sludge that can be used in the process of the invention occurs in the treatment of petroleum products for the production of mineral oils. Another mineral acid mud is at the reaction of a relatively concentrated sulfuric acid with an industrial fuel oil cut such as "cat light gas" oil. A particularly preferred mineral acid sludge is obtained in that spent alkylating sulfuric acid with "cat light gas" oil is converted, the reaction product is left to stand to form separate phases and the "lower Layer is wiped off. This lower layer is the acid sludge.

The carbonized or sintered particles obtained in step (h) of the process according to the invention can be activated by any of the known processes. The activation is preferably carried out by placing the carbon particles in a reactor and in the

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Reactor steam or air at a temperature in the range of 900 to 1200 ° C is initiated. "The carbon particles are held at these reaction conditions for about 30 minutes to 6 hours or more. The activation time depends on the applied activation temperature, the type of gaseous activating agent used and the particle size of the activating carbon product as well as the type of reactor used. For carbon particles of the same size the activation time also depends on the type of carbon products used and how they are manufactured.

A typical modified furnace with multiple hearths, such as that used for the carbonization and activation stages (4) and (5) of the present method can be used with particularly favorable results is shown in the drawing. Of the Oven 1 with a plurality of hearth locations has a plurality of hearth areas 2. The product to be carbonized, which in general is in the form of small spheres, is introduced into the furnace 1 from the storage container 3 through a valve 4. Everyone the separate oven areas 2 is heated with heating devices not shown in the drawing, so that the temperature in each oven area independently at any desired temperature can be held. In each hearth area there is a rotatable stirring arm 5 which is designed like a rake is and is connected to a drive shaft 6, which means

-10-

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a drive device 4 and driven via the transmission O. will. When the drive shaft 6 rotates, the rake arms move the granular carbon particles through the openings 9 in each hearth area, so that when the oven is operating correctly, the granular carbon product continuously flow down from the reservoir 3 through the hearth areas 2 of the oven and finally out of the bottom of the oven at 10 flow into a storage vessel 11 and on to the packaging area. In the upper part of the furnace 1 are a number of Fireplaces 12 are provided for each of the upper hearth areas 2 so as to remove the gases and volatile components from each of the upper To be able to dissipate hearth areas independently of one another. This chimney shafts 12, each with control devices for Can be equipped to prevent a gas return, lead to a common chimney shaft 12 through which the volatile constituents and gases are discharged or to one here recovery device not shown are directed. For each of the hearth areas 2 that are below those in which the carbonization is carried out, a steam line 14 is provided to convey the activation gases or -to be able to introduce vapors into each stove area 2. The activation gases can come from a single source 15 close to the ground of the furnace 1 are supplied.

In a small approach typical of the process according to the invention for the production of small-particle carbonized carbon -11

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Particles become 100 g carbon cores in a metal tube used, the product being heated to about 955 ° C, before it is mixed with a mixture of about 4 SCFH (standard Cubic Foot per Hour) air and 100 g water vapor per hour is brought into contact. Activation is within less than 3 hours completely. Activation can also be carried out by putting flue gas or nitrogen together is used with water vapor.

The activated carbon products produced according to the invention can can be used advantageously in many ways, as is known to those skilled in the art. E.g. they can be used to refine and decolorize industrial oils, as ion exchange products, for decolorization and cleaning of sugar solutions and syrups, for Purification of Yfasser and for the treatment of industrial wastewater and the like can be used.

In the context of the present invention, the term "roundness" means the average radius of the corners and edges divided by the radius of the largest inscribed circle. Roundness is not necessarily the same as spatial shape and is generally called the ratio of the nominal diameter of a particle to the maximum intercept of the particle. The nominal diameter is that diameter a sphere that has the same volume as the non-round particle. The maximum intercept is the diameter of one -12-

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Sphere surrounding the particle. Although roundness and three-dimensional shape are identical for a perfect sphere, you can have particles with a large three-dimensional shape but little roundness and vice versa. A more detailed discussion of both terms is found in the book by Krumbein and Sloss, Stratigraphy and Sedimentation (Vi.H. Freeman Company, San Francisco, 1951) pages 78-83.

The method according to the invention is further illustrated by the following examples, where the amounts of the various ingredients are given in parts by weight, unless otherwise indicated,

example 1

A. An acid slurry is prepared from a "cat light gas" oil (CLGO, with the typical properties given in Table I) and sulfuric acid at 82 ° C and a contact time of 30 minutes, mechanically at a rotational speed of 1550 rpm , is stirred. The cat light gas oil was added to the reaction vessel at a rate of 1.1 pounds per minute and the sulfuric acid at a rate of 0.77 pounds per minute. A total of 58.9% by weight "cat light gas" oil and 41.10 % by weight sulfuric acid were used. The product obtained consisted of 61.68 wt. ^: . c.or reaction uno cer 4ufarbe; -tuiv ^f ., _v

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- 13 - de ι 'acid produced in this way Viscosity of 87 24 27 "-Oil -14- evaporate. It was found that other one 11 70 0, 5 sludge has a density of 1.4 g / ccm ι I. O, 29 195 89 Was 10,000 CPS at 24 ° C (75 ° F) Typical properties of "cat light gas 00 33 Table I. API density 99 23 2, Specific weight (15.6 C) 1, 75 Molecular weight (osmometer) 12th Calculated cetane number 213, Viscosity, CS (37.8 ° C) 235 9 CS (98.9 C) 242, 0 ASTM distillation, ⁰ C 250, 8th Initial boiling point 256, 6th 5 % 262, 7th 10 % 266, 0 20 % 274, 5 30 % 281, 0 40 % 290 5 50 % 301, 5 60 % 325 5 70 % 99 0 80 % 1, 0 90 % 0, 0 End point 0 . % Distillate % Residue % Loss Wt% C Wt% H Wt% S Wt% ash

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- 14 -

B. The acid sludge prepared according to A and a bituminous coke powder of class A high in volatile products (Table II gives the most typical constituents of the coal powder) were prepared to form small particles of approximately spherical shape in the following manner: A total of 67 % by weight coal with a particle size of 98 to 100 TyIer-Masehen and 33% by weight acid sludge were mixed at room temperature for a total of about 15 minutes in a mixer with belt-shaped mixing tools and product removal at the end of the mixer. Those portions of the particulate product with a particle size in the range of 4 to 18 Tyler meshes were removed at the outlet opening, while the particles with a particle size of more than 4 and less than 18 Tyler meshes were returned to the mixing container. The product had a bulk density of 0.741 g / ccm.

Table II Typical properties of carbon powder

Measured according to literature

As stated

% Moisture % volatiles % bound carbon % ash % sulfur

3.30

34.53 59.37

2.80

0.58

100.58

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Table II continued

Measured According to literature analysis
% Carbon
% Hydrogen
% Nitrogen)
% Oxygen)
% Sulfur
% Ashes 84.36
5.61
7.49
0.72
1.82 83.46
9.27
(1.51
(6.03
0.49
3.24 100.00 100.00 Sulfur elformcii
% Pyrite Sheep
% Sulfate-sulfur
% organic bound sulfur 0.00
0.03
0.46 0.49 0.14 Analysis of the ash residue
% P ₂ O ₅ 44.74 % SiO ₂ 13.73 % Fe ₂ O ₃ 27.89 % Al ₂ O ₃ 0.96 % TiO ₂ 3.22
1.82
1.23 % CaO
% MgO
% SO ₃ 6.27 % indefinite products

100.00

Example 2

A. Product prepared according to Example 1B was according to the invention in a rotary mixer at one speed of rotation of 4.5 rpm, a temperature of 121 ° C. and a residence time of 15 minutes, with air flowing through the Dryer at the rate of 640 cubic feet / hour. The air flow was such that the volatiles from the dried Kchleprcaukt from the drying egg 6-

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chamber were discharged. The air was passed through the dryer in the same direction of flow as the solids. The material was fed to the dryer at a rate of $ 48.25 / hour and withdrawn at a rate of $ 45.74 / hour. The weight recovery was 94.82 % based on the material fed to the dryer.

B. The product dried according to A of this example was deacidified by using the same device as in A at a rotation speed of 4.5 rpm., a temperature of 343 ° C, a residence time of 15 minutes and a Feed rate of 54.74 pounds per hour was passed with gas and solids flows as in A were conducted in parallel. The deacidified product was de-acidified at a rate of 41.49 US pounds / hour in one Yield of 75.79 wt% obtained. The product had a Particle size in the range from 4 to 18 Tyler mesh and a bulk density of 0.655 g / ccm.

'·. The product deacidified according to B of this example was carbonized by forming a thin fixed bed of the material in a furnace with an inert atmosphere and raising the temperature of the furnace from room temperature to 955 ° C. within 30 minutes. The gev.-naughty yield of charred Prcdulit beru? 79.0 %. Dr. «3 product would have a bulk density of 0.7 ( ^r 'iVcc:;. -1V--

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D. The charred product obtained according to C of this example was placed in a fixed bed reactor at a temperature of 955 ° C for various times with steam in an amount of 120 ccm / hour. activated and the following results obtain:

Activation time (min.) 40 60 80 Wt% yield 70.9 57.0 44.3 % Gasified 29.1 43.0 55.7 Bulk density, g / ccm 0.608 0.489 0.422 Wt% CCl / adsorption 37.3 61.2 85.1

An induction time of 8.79 minutes was observed.

Example 3

For comparison purposes, this example describes a method not encompassed by the present invention.

A. The procedure of Example 1A was repeated except that the air flow used to remove the volatiles the product fed to the rotary mixer is guided in countercurrent from the removal end to the feed end of the mixer v / urddEi and thus the coal product in the vicinity of the Introductory end of the dryer with the volatile components has been contaminated from the products that have already flowed further in the dryer. The starting product was in an amount

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of 30.8 pounds / hour was fed into the mixer and the product was formed at a rate of 28.93 pounds / hour with a weight yield of 94.09 % .

B. The procedure of Example 1B was repeated using the material obtained in A of this example. The feed rate was 32 pounds per hour and the product was recovered at a rate of 24.86 pounds per hour in a weight yield of 77.69 %. The product obtained had a density of 0.680 g / ccm.

C. The procedure of Example 2C was repeated with the product obtained according to B of this example. A weight yield of 76.6 % was obtained and the product recovered had a bulk density of 0.762 g / cc.

D. The activation step of Example 1D was carried out with that according to C this example repeated product obtained. The following results were obtained:

Activation time (min.) Wt -..% Yield Gevt ~% gassed bulk density, g / cc wt .- o ^ CCT adsorption?

70

83.2 62.7 42.1 16.8 37.3 57.9 0.664 0.558 0.452 20.9 52.4 83.9

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There was an induction time of 36.73 minutes for this
Product detected.

Example 4

A. The material obtained in Example 2B was carbonized in an oven with six hearths, each 30 inches
(approx. 76 cm) in diameter. The product was introduced at the rate of 75 pounds per hour and the residence time
was 1 hour. The approximate temperature of each hearth
(Gas phase), seen from the topmost hearth:

Stove no. Temperature, C 1 171 2 476 3 560 4th 713 5 835 6th 838

The gases from each of Hearth Nos. 2, 3, 4, 5, and 6 were vented separately during the char, see above
that volatiles on the cole products during
their passage through the furnace is not countercurrent
could move to the head of the hearth. The weight yield was 76.4 %. The product had a bulk density of 0.755 g / ccE.

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2V57O9R

3. The product obtained according to A of this example was activated and activated as described in the example, the oven described in A of this example being used with several hearths and "a temperature of 955 ° C. (gas phase) being used. Steam was fed into the hearths no 2, 3, 4 and a total of 120 pounds / hour The carbonized product was fed into the furnace at 20 pounds / hour and the furnace residence time was 3 hours on the hearth No. 1. The activated charcoal yield by weight was 59.4 %, the product had a bulk density of 0.548 g / cc, and carbon tetrachloride was absorbed in an amount of 59.5% by weight.

Example 5

This example is also given for comparison purposes and does not fall under the scope of the present invention.

A. The procedure of Example 4A was repeated, except that the volatile constituents formed in the carbonization were stripped off via stove number 1 only. The yield by weight was 61.9 %. The carbonized product had a bulk density of 0.722 g / ccm.

B. The procedure of Example 4B was repeated, wherein

-21-

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_BA0

the product obtained according to A of the present example was used as the starting product. The weight yield was 79.6 %. The activated product had a higher bulk density of 0.625 g / ccm and carbon tetrachloride was in a smaller amount, namely 25.0 Gev /, in comparison with the activated carbon obtained according to Example 4B. -% absorbed.

Claims

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Claims (6)

Patent claims: 1. Process for the production of particulate activated carbon, characterized in that one a) a particulate carbon material with a petroleum acid sludge mixed and deformed to form shaped particles, b) the shaped particles obtained in (a) by heating hardens, e.g. c) the product obtained according to (b) by further heating deacidified, d) the product obtained according to (c) carbonized by further heat treatment and thereby the total amount of volatile components are removed from this product in such a way that they are removed as much as possible and as quickly as possible as possible after the discharge from the vicinity of the carbonized particles are removed so that the volatile constituents are no longer in contact with the total amount of carbonized particles immediately after release come and e) the shaped and carbonized ones obtained according to (d) Particles activated in a manner known per se. 2. The method according to claim 1, characterized in that step (a) at a temperature in the range of about -32 is carried out up to plus 150 C. -23- 209822/0911 3. The method according to claim 1 or 2, characterized in that step (b) at a temperature in the range of about 82 to about 150 ° C. 4. Process according to Claims 1 to 3, characterized in that that step (c) is carried out at a temperature in the range from about 150 to about 370.degree. 5. The method according to claims 1 to 4, characterized in that step (d) at a temperature in the range of about 370 to about 815 ° C. 6. Process according to Claims 1 to 5, characterized in that that step (e) is carried out at a temperature above about 815 ° C. 209822/091 1 Blank page