DE2461165B2 - Method and device for improving the sorption capacity of activated carbon - Google Patents

Description

The invention relates to a method and a device for improving the sorption capacity of activated carbon by heating and subsequent quenching by means of a cooling medium.

From British patent specification 12 63 603 it is generally known that the sorption capacity is more inorganic Sorbent by heating to a temperature above 300 ° C and subsequent quenching can be improved to a temperature of less than - 75 ° C. Sorption itself but usually takes place at room temperature or a slightly higher temperature. - Under the The term "sorption" is to be understood as both physical sorption, including capillary condensation also chemical sorption.

In the above activation method according to British patent specification 12 63 603, for Quenching the sorbent in question immersed in a liquefied gas at a very rapid rate To achieve cooling. In the course of the experiment, however, it has been shown that such rapid cooling is more impregnated Activated carbon pulverization of the carbon or the impregnation and thus also a reduction in the Causes sorption capacity.

The invention has for its object to improve the above method in such a way that the called pulverization is avoided, and that at the same time the treated activated carbon one in proportion Unchanged or increased sorption capacity is achieved compared to the known activation processes.

This object is achieved according to the invention in that the coal is first ^{heated in an inert atmosphere to a temperature in the range of 50-30O 0} C and then quenched to a temperature of less than -66 ^{0 C by cooling in indirect heat exchange} will.

The cooling according to the invention through a partition wall, for example a pipe wall, is advantageous because the impregnated coal particles are not broken up and maintain their hardness while increasing Sorption improvement is achieved. These advantages achieved are essential in gas filter devices for shelters, fighting vehicles and the like. In these cases the resistance of the Coal particles against breaking, especially important when exposed to shaking and vibrations.

As a measure of such resistance to the breaking or grinding of the coal particles, an average particle size χ is used which is achieved by grinding and subsequent sieving in accordance with the following procedure. This mean particle size is defined by the following formula (K. W i η η ak ker, E. Weingärtner, Chemische Technologie, Volume I, p. 52, 1950):

Töö

or

log Nog -—- = nlog.v - / 1 log * + log log.

In a logarithmic coordinate system, equation (2) gives a straight line. - R denotes the percentage by weight of the total amount of particles that a sieve with a mesh size of χ mm cannot penetrate.

π denotes the slope of the straight line and is a measure of the homogeneity of the coal particles, χ denotes the statistical mean diameter of the particles. Recording the measured values of R and χ in a logarithmic coordinate system results in a straight line, and the mean particle diameter χ corresponds to R = 36.8%.

The invention also relates to a device for

Carrying out the process with a tube furnace for heating the activated carbon and one below arranged, against the tube furnace with a shut-off device closable cooling chamber with a Partition between activated carbon and cooling medium.

This device according to the invention is thereby

W characterized in that the cooling chamber is annular and with inner and outer walls in a cooling medium container is arranged and both inside and outside the ring shape of the Cooling medium container separated by the partition

5 «) is.

During the moderate quenching of activated carbon in a cooling chamber according to the invention achieves the following advantages:

a) The carbon particles achieve a higher sorption capacity than activated carbons, which are known by Procedures are activated.

b) The hardness of the activated carbon is retained and corresponds to the hardness of the starting material.

c) Regulated inert cooling atmosphere (e.g. H2, He, Ar), the unwanted reactive gases slept.

d) Controlled cooling rate, which enables reproducible properties.

Other features of the invention as well as properties and uses of the carbon product produced are illustrated in the examples below

example 1

Physical sorption as a function
the cooling rate (° C / min.)

The present example shows the chloropicrin uptake of Cu-Cr-Ag-impregnated carbon in relation to the cooling rate. The charcoal is of the Pittsburgh ASC 12 χ 30 type and is preferably used for the manufacture of gas masks that protect against war gases such as chloropicrin. Five carbon samples were activated for 2 hours at a temperature of 168 ± 5 ° C. Four of the samples were filled into 30 cm long thin-walled steel tubes of different diameters, as indicated in Table 1. The tubes were placed in a cylindrical furnace. The temperature was measured by means of a thermocouple placed in the center of the carbon layer.

The temperature fluctuations were recorded on a 20 mV recorder. The quenching process was carried out by removing each tube individually from the furnace and quenching it in liquid nitrogen. The samples were flushed with N2 during activation and during the quenching process. All samples were kept in liquid N2 until the lowest temperature of approx. -190 ^° C. was reached. The charcoal was then warmed to room temperature while flushing with nitrogen and stored in plastic bottles in a nitrogen atmosphere until a capacity test was made.

The temperature rate is defined here as ° C / min. in the temperature range from 168 to 0 ⁰ C. In this temperature range, the observed cooling curve was linear.

The throat in sample No. 5 was placed in a steel pipe with perforated walls. 18 mm.

During this quenching process, the liquid nitrogen was in direct contact with the activated one Money. As a result, a significantly faster cooling rate was achieved than with the other four samples. Even this sample was constantly surrounded and flushed with nitrogen

75 ml of all samples tested with chloropic ring gas. As can be seen in Table 1, this is Carbon volume in tube 1 and 2 too small for a chloropicrin test. To have enough carbon volume for the To obtain picrine test, three samples each from these two tubes were activated

The capacity measurement was carried out so that 150 mg / min. Chloropicrin with 28.51 dry air diluted was passed over a bed of coal of the following dimensions.

The breakthrough of the gas was shown on a color indicator. Upon reaching a concentration from 10 ppm the indicator turned yellow. In Table 1 are the test results and the test conditions reproduced.

Volume: 75 cm ³ Area: 30cm3 Bed height: 2.5 cm Linear speed: 10 m / min

Table 1 Inner
Pipe-0 Activated carbon
volume in
pipe Cool down time Cooling rate Chloropicrin
capacity Chloropicrin
capacity Capacity
modification**) 0 pipe
No. mm cm ³ Min. C / min. Min./ml mg / ml % + 25.7 _ 0.70 105 *) + 18.1 0 12.4 35.00 0.60 280 0.88 132 + 8.5 1 15.4 49.00 0.70 233 0.83 124 + 20.0 2 19.2 78.00 1.20 140 0.76 114 + 23.8 3 25.0 129.00 2.20 76 0.56 84 4th 22.0 80.00 0.38 429 0.53 80 5

*) Original charcoal. Average capacity of 8 measurements. ReI. Standard deviation + 4.5%. **) Change in capacity compared to the original coal.

The table shows that an increased quench rate results in increased sorbent capacity. Experiment no. 5 shows that direct cooling at the highest cooling rate does not lead to the highest increase in capacity. The controlled cooling in pipes has the advantage of preventing the coal from glowing up. ASC coal glows during the activation process in contact with air even at 16O ⁰ C, which is an abnormally low Anzündungstemperatur. The experiments suggest. that an optimal cooling rate leads to the highest capacity. This rate is below W) 429 ° C / min., But above approx. 76 ° O min.

Example 2

Table 2 shows the particle size distribution of the original products. shown, both quenched (BK) and ^br > slowly cooled (LK.) granules of the coal types Pittsburgh ASC (ASC), Sutcliffe Speakman 607 (SS 607). The quenching process takes place in a metuli tube with a diameter of 18 mm, as described in Example 1.

Table 2

Types of coal

Cooling method

Activation weight distribution (%) of the particle size temperature

C 3.36mm 2.00mm 1.00mm

ASC
ASC
ASC
ASC
ASC
ASC
ASC

SS 607
SS 607
SS 607
SS 607
SS 607
SS 607

original
AS in the pipe
AS in Π. N ₂ *)
LA in the pipe
AS in the pipe
AS in (1st N _2nd
AS in the pipe

original
AS in the pipe
AS in fl. N ₂
AS in the pipe
AS in fl. N ₂
AS in the pipe

160 160 160 300 300 375

160 160 300 300 383 9.2
5.7
4.5
6.2
4.8
5.4

88.0
88.1
87.8
87.3
87.8
88.7

63.3 49.4 47.2 61.7 52.2

47.4

2.8 6.1 7.7 6.5 7.4 5.9

36.7 50.6 52.8 38.3 48.8

*) In fl. N ₂ .

LA = slowly cooled down.

AS = quenched coal.

From Table 2 it is apparent that the Ab ^ h stretching process in tubes with activated granules to 300 ⁰ C, the granule size has no significant shift in the direction of smaller particle size or result in dust. That means z. B, that the pressure drop over a bed with (AS) activated coal is not higher than over a bed with the same dimensions consisting of original coal.

The resistance of the granulate to comminution by grinding in an analytical mill was measured consisted of a room with a horizontally rotating steel knife. The rotation speed was 20,000 revolutions / min. 10 grams of each sample was crushed for 2 seconds and then sieved in the middle of a test sieve of the type: test sieve DIN

Table 3

4188. The results are given in Table 3.

From Table 3 it can be seen that the activation is quenching directly in liquid nitrogen, as well as di <

Heating of the coal in tubes over 300 ⁰ C unc

subsequent quenching also to a reduk

tion of the mean particle size leads.

The figures given, ± 4.4% and ± 3.2 "M 3-j, correspond to the relative standard deviations be repeated attempts at the crushing and sieving processes of the respective original coal types.

From Table 3 it can also be seen that quenching ir pipes results in smaller reductions in the mean particle diameter χ than quenching directly in liquid stick material.

Ver Money- Cooling cooled down. Active Weight distribution of the particle size > 2.00 > 1.00 > 0.50 1 ), 72 Change of 0 search- types procedure much mm mm mm 1 ), 95 middle -9.0 No. foresight > 3.36 > 0.50 ( ), 87 Particle -28.0 tempe- mm mm >, 00 **) diam. -5.0 rature 39.5 42.4 , 97 -13.0 C. 39.0 44.6 , 87 % 1 ASC original 26.9 52.6 18.1 1 , 97 -1.5 2 ASC AS in the pipe 160 23.0 47.4 16.4] , 90 -6.5 3 ASC AS in fl. N ₂ 160 31.2 47.8 Middle , 89 -1.5 4th ASC LA in the pipe 160 25.8 47.4 'items- -5.0 5 ASC AS in the pipe 300 36.7 32.5 lurchm. -5.5 6th ASC AS in the pipe 375 33.3 32.0 7th SS 607 original 0.7 32.9 33.9 8th SS 607 As in the pipe 160 2.0 34.3 33.0 χ mm 9 SS 607 AS in fl. N ₂ 160 1.8 32.5 34.9 , 00 *) 10 SS 607 AS in the pipe 300 1.5 33.5 33.9 , 00 11 SS 607 ASinfLN ₂ 300 0.9 20.5 0.91 12th SS 607 AS in the pipe 383 1.1 29.6 ( AS = Quenched coal. 21.0 ( LA = Slow 26.8 ( 30.1 I. 32.7 31.4 31.2 31.7 31.5

Example 3

This example shows the physical sorption capacity of CuCrAg-impregnated carbon of the type Pittsburgh ASC 12 χ 30, which has been activated 110 -800 ⁰ C in the temperature range and quenched in tubes. For comparison purposes, activated carbon and slowly cooled in tubes, as described in Example 1, is also listed. The capacity of the carbon was tested with chloropicrin, under the same conditions as described in Example 1. The impregnation has the following composition: Cu 6%, Cr 2%, Ag 0.05%. These elements are in l ⁷ orm of salts, oxides and hydroxides on the carbon surface before. The results are shown in Table 4.

Table 4 Activation Capacity LA *) mg / m! Capacity AS **) mg / ml Change in capacity,% ***) 0 AS 0 Experimental temperature 105.0 105.0 + 50.0 + 27.2 No. C. min / ml 52.5 min / ml 76.5 LA + 17.1 + 38.0 _ 0.70 123.0 0.70 145.0 + 11.4 + 60.0 1 110 0.35 93.0 0.51 168.0 + 4.7 + 48.5 2 130 0.82 100.0 0.97 156.0 + 6.6 + 25.7 3 160 0.62 112.0 1.12 132.0 + 4.7 + 14.3 4th 200 0.67 100.0 1.04 120.0 + 11.4 + 14.3 5 250 0.75 117.0 0.88 120.0 - + 61.0 6th 300 0.67 - 0.80 41.0 7th 400 0.78 0.80 8th 800 - 0.28 9

*) Capacity as a result of slow cooling LA. **) Capacity as a result of quenching AS. ***) Change in capacity compared to the capacity of the original coal, experiment No. 1.

From Table 4 it is apparent that the quenching process (AS) in pipes has an increase in Chlorpikrinkapazität result, when activated coal at temperatures below 300 ° C, especially in the temperature range 160-200 ⁰ C. Activation of more than 300 ⁰ C, followed of quenching gives very little increase or even a decrease in capacity. Comparative tests with slow cooling (LA) generally lead to a slight increase in capacity and, in some cases, to a reduction in capacity compared to the original product.

Example 4

In the example below, the activation and quenching demonstrated an increase in the chemical sorption capacity. The coal and the Activation methods are the same as described in Example 3.

Cyanogen chloride has been used as a typical chemisorbent gas (CICN) is used. It can be assumed that cyanogen chloride with the impregnation (Cr) according to the following Scheme reacts:

Cl · CN + H ₂ O - ^ - NH ₃ + CO ₂ + HCl

The presence of water molecules is required. It must therefore be sorbed or chemically Bound water must be present so that the oxidation can take place.

The measurement of the cyanogen chloride capacity of the activated carbon was carried out under the following conditions:

Carbon volume in the filter: 75 cm ³ Filter area: 30 cm ² Bed height: 2.5 cm Total gas volume: 30 l / min. Linear speed: 10 m / min. Carrier gas: air Relative humidity: 0% Cyanogen chloride dosage: 72-3 mg / min Filter temperature: 18 ± 0.2 ° C

The breakthrough of the cyanogen chloride gas was checked by means of a color indicator. The results are in Table 5 reproduced.

Table 5 Activation
temperature
"C LA *)
Cyanogen chloride capacity
min / ml mg / ml 12.90
8.65 AS **)
Cyanogen chloride capacity
min / ml mg / ml 12.90
4.30 Change in capacitance
LA ***)
AS Experimental
No. 110 0.180
0.120 0.180
0.060 -33.3 -66.7 1
2

ίο

rortset / iinj! Activation UV) 'capacity AS **) mg / ml Change in capacity ***) AS Experimental temperalur C'hlorcx mp / nil 10.40 LA % No. C. min / ml 9.35 13.30 % -19.4 130 0.130 9.35 Cyanogen chloride capacity 15.80 -27.8 + 3.1 3 140 0.130 9.50 min / ml 14.00 -27.8 + 22.5 4th 160 0.132 5.70 0.145 14.40 -26.6 + 22.5 5 200 0.080 9.00 0.185 7.20 -55.5 + 11.6 6th 270 0.125 10.40 0.220 7.92 -30.6 -44.2 7th 300 0.145 11.50 0.195 0.70 -19.4 -38.6 8th 400 0.160 - 0.200 -11.1 - 94.5 9 800 - 0.100 - 10 0.110 0.010

*) LA = slowly cooled coal. **) AS = quenched coal. ***) Change in capacity compared to the capacity of the original coal, experiment No. 1.

Gehl from Table 5 shows that activation in the region of 160-27O ° C, and then quenching in an increase in Chemiesorptionskapazität result compared to the original product, trial # 1. Activation at 300 ⁰ C and above has a negative impact. This also applies to slow cooling.

If one compares with example 3, one recognizes that the physical sorption as well as the chemical sorption Can be increased significantly by activating the carbon in the temperature range 160-300 ° C and then Quenching, d. H. a single activation process produces two positive sorption effects at the same time achieved. This result is surprising since physical sorption and chemical sorption are essential are different operations. In contrast to selective effects, a combination of Properties of coal, resulting in an accumulation of different types of gas with different sorption mechanisms means.

Example 5

In this example, the physical sorption (chloropicrin) improvement of Cu-impregnated is used Activated carbon of mineral origin shown. The impregnation consists mainly of one and divalent copper oxides and / or hydroxides. Since there is no chrome, the impregnation is ineffective in terms of chemical sorption (cyanogen chloride). It is typical old (aged) coal, 12 years ago in ventilation systems (air raid shelters) had been installed. The coal contains moisture and has a poor sorption capacity on. Table 6 shows capacity improvements as a result of activation.

k Table 6 Activation LA *) mg / ml AS **) mg / ml Change in capacity ***) _ AS _ ! 5
'Z experimental temperature capacity 23.7 capacity 23.7 LA + 29.5 % + 27.4 I ^No. C. min / ml 31.7 min / ml 30.2 % + 3.3 + 43.1 j _ 0.33 24.5 0.33 33.9 + 12.6 + 58.2 I ι 80 0.44 26.7 0.42 37.5 + 43.1 + 64.5 % 2 130 0.34 33.9 0.47 39.0 + 2.9 + 27.4 1 3 160 0.37 23.0 0.52 30.2 200 0.47 0.54 5 250 0.32 0.42 6th

*) LA = slowly cooled coal. **) AS = quenched coal. ***) Change in capacity compared to the capacity of the original coal, experiment No. 1.

The test conditions are the same as in Example 1. The table shows that activation and subsequent Quenching gives the highest capacity values. This shows that old (used) coal can be improved. The capacity values are below those achieved with ASC coal became. This is due to the considerably higher physical sorption capacity of the ASC-Kohie in comparison to the mineral coal mentioned.

Example 6

This example shows the increase in the physical sorption capacity of unimpregnated coal shown as the result of controlled heating

in the temperature range below 300 ° C and the quenching process in a concentric tube surrounded by liquid nitrogen. A system for controlled activation and quenching is shown schematically in the figure. The system consists of a vertically mounted tube furnace A with a diameter of 10 cm and a 100 cm long heating zone B. The furnace is connected to a cooling unit C. This consists of a concentric tube D, which is in direct connection with the furnace and has a valve V ₂ . The connection between the furnace and the cooling pipe D ₁ D \ can be interrupted with the aid of a valve Vi. The cooling tube is surrounded by an outer (E) and an inner (F) volume, which is filled with cryogenic liquid, e.g. B. liquid nitrogen is filled. The cryogenic liquid is introduced into the outer container through the valve Ks and the opening G and passes through the openings Hi, H ₂ into the inner container F. The nitrogen evaporates through the openings / |, I ₂ (diameter 5 cm) the inner container to the gas volume in the outer container (E). From here the nitrogen flows through opening K into the atmosphere or to a gas liquefaction plant. When coal granulate is activated, it is fed into the tube furnace via valve K ₆ with valve Ki closed. Inert gas e.g. B. Nitrogen is circulated again through the granulate and through the valves K ₃ and K ₄ with the aid of the pump P. The moisture in the coal is led out with the gas and removed at room temperature or below using another sorbent (in container L) . The dry gas is returned via pump P.

The valve V \, is opened for quenching. The coal enters the concentric tube D by means of gravity, where the heat transfer takes place instantaneously and radially from the center of the coal layer to the tube walls. From there, the heat is carried on by evaporation of the liquid nitrogen. Normally, carbon has very low thermal conductivity properties, so that the heat transfer in the axial direction is minimal. The temperature difference in the axial direction is also almost zero.

Before the granulate goes from the furnace to the cooling pipe D

Table 7

reaches it, it is flushed _{through valve K 6 with inert gas.} The granulate is stored in the cooling tube until it has reached the lowest possible temperature, that is to say to the boiling point of the cryogenic cooling liquid. The Granu-

> lat reaches the container M with venti ¹ Vj under the cooling pipe by removing a movable base N. This operation is carried out by moving the tank M from the Q level to the R level. The granulate is placed in the container M (which is also

ίο can be warmed) stored until it is room temperature has reached.

81 unimpregnated Sutcliffe Speakman 607 charcoal granules were activated and quenched as described above. The charcoal was ^{heated to 200 °} C. and flushed through with nitrogen at this temperature for 24 hours before it was quenched. Liquid nitrogen was used as the cooling liquid. 150 ml of the activated carbon was tested for its chloropicrin capacity. The test conditions were the same as in Example 1 except for the volume and the bed height (5 cm). The breakthrough time was 76 minutes, corresponding to a capacity of 76 mg / ml charcoal. The original unactivated char had a capacity of 68 mg / ml char. The increase in capacity is therefore 11.7%.

Example 7

Different amounts of coal of the same type were, as in Example 6, at different temperatures doors activated and deterred. The capacitance measurements were made in the same way as in example 6.

In one experiment (experiment no. 6) the charcoal was activated and slowly cooled by following it j5 heating in the tubes has been directed into the cooling tube. This was surrounded by an atmosphere at room temperature. During the cooling down the coal was with Flushed with nitrogen.

The activation time was 24 hours in all cases and the activation atmosphere consisted of nitrogen. Table 7 shows the results of the capacity measurements and the result of Example 6.

Trial activation volume
No temperature of the coal

C 1

Activation procedure

Cooling rate

C / min.

Breakthrough capacity
Time

Min.

mg / ml

Change in capacity *)

1 - - - 29.3 **) 68.0 68.0 - 2 200 2.0 AS 35.0 **) 73.5 73.5 8.0 3 200 4.0 AS 38.3 **) 74.5 74.5 9.5 4th 200 8.0 AS 40.0 ***) 76.0 76.0 11.7 5 160 2.0 AS 8.4 ***) 86.0 86.0 26.5 6th 160 2.0 LA 800 ****) 71.0 71.0 4.4 7th 160 0.2 AS - 15.0 30.0 -71.0 8th 286 0.2 AS - 79.0 79.0 16.1 9 349 0.2 AS 55.0 55.0 -19.2

*) Change in capacity compared to the capacity of the original coal, experiment no. 1. **) The cooling rate is taken from the temperature interval +40 to -40 ° C of the temperature curve. ***) The cooling rate is taken from the temperature range +152 to +93 'C of the temperature curve. ****) Quenched directly in liquid nitrogen.
LA = slowly cooled coal.
AS = quenched coal.

It can be seen from Table 7 that the capacity increase of the activation temperature and of the Cooling rate is dependent. The quench activation in pipes results in the greatest increase in capacity at 160 ° C Activation followed by cooling in direct contact with liquid nitrogen has a negative effect.

Example 8

In these experiments, the importance of the cooling rate for increasing the capacity of non-impregnated Coal of the same make and type as in

Example 7 demonstrated. 2 l of each sample were fui used these attempts. Nitrogen and helium were used as the activation and cooling atmosphere applies The apparatus described in Example (was used for the experiments

Coal granules with a larger particle size (particle diameter) have a higher thermal conduction resistance than granules with a smaller particle diameter. Larger «granulates are therefore cooled more slowly. The total heat transfer coefficient (kcal / m ² · hr) in the cooling tube depends on the quality of the coal granulate and the atmosphere in the intergranular volume and in the pore volume of the granulate.

Table p

Trial Activation Cooling Activation Cooling Breakthrough Capacity Capacity

No. atmosphere atmosphere temperature rate *) time increase **)

C C / min. Min. Mg / ml%

N;

Hey

Hey

- - 68.0 68.0 - 200 29.3 73.5 73.5 8.0 200 114 82.0 82.0 20.6

*} The cooling period is calculated within the temperature range -MO to -4G ¹ C of the Terripeiraiurvcr'auiliurve. **) The increase in capacity compared to the capacity of the original coal, experiment No. 1.

The activated granules were based on the chloropicrin capacity tested as in example 1. These results were combined with the results from example 7. Experiments 1 and 2 shown.

Table 8 shows that a significantly higher cooling rate can be achieved by increasing the Heat transfer coefficient with the help of a gas (He) with a higher heat conduction constant than nitrogen, which leads to an increase in capacity.

Example 9

75 ml samples of non-impregnated mineral carbon of the type Sutcliffe Speakman 206 A were taken during 3 Activated hours in a quartz tube with an internal diameter of 18 mm. The pipe with the coal was on then quenched in liquid nitrogen or slowly cooled to room temperature. Samples were rinsed during the entire process, approx. 0.51 / min. The granules were then taken under

Table 9

The following conditions have been tested for its chloropicrin capacity:

Granules:

Bed volume:
Bed height:
Bed area:
Air supply:

Linear speed:
Picrin concentration:
Picrine supply:
Relative humidity:

1.68-0.50 mm,
10-30 BSS mesh
8 ml
4.5 cm
2.35 cm ²
2.35 l / min.
10 m / min.
5 mg / 1 air
8.75 mg / min.
0%

In Table 9 the results are given together with the capacity of the original product. The origins The capacity is very low compared to the chloropicrin capacity of ASC carbon (Examples 1 and 3 namely 105 mg / ml.

Experimental Activation Activation Cool down By capacity Capacity No. temperature procedure rate*) fracture increase**) Time C. C / min. Min. mg / ml % 1 - - 19th 20.7 2 108 AS 114 43 46.8 126.0 3 108 LA 12th 32 35.0 69.0 4th 207 AS 118 54 59.0 185.0 5 207 LA 21 27 29.5 42.5

*) The cooling rate in the temperature range 108-50 C b; i: w. 207-50 C of the temperature curve

measured.

**) Increase in capacity compared to the capacity of the original coal, experiment No. I. LA = slowly cooled coal.
AS = quenched coal.

The table shows that charcoal with a low physical sorption capacity is produced by activation and quenching experiences a substantial capacity improvement.

Example 10

Tabel 10 Cooling weight Kapa Capacity Ver Activation lung d. Money- ity valid search- foresight procedure niters taking *) No. temperature ren G mg / g % C.

Coal granules of the Sutcliffe Speakman 607 type were activated at 160 ° C., as described in Example 6; n. The granulate was then tested for the benzene capacity. A dry stream of air saturated with benzene vapor (0.27 l / min.) Corresponding to 4.23% by volume at 5.7 ° C. was passed through a filter with a volume of 7 ml, a bed height of 6 cm, a bed area of 1 , 16 cm ^{2 passed} at 2.34 m / min, linear speed and 25 ° C filter temperature.

This corresponds to a benzene dosage of 42.0 mg / min. The benzene uptake was determined by weighing the Granules checked before and after breakthrough. The breakthrough of benzene came with a Thermal conduction detector measured and is defined in this example at the time in which the benzene concentration has reached the same value as the benzene concentration in the air when it exits the filter the supply air. At this point the experiments were terminated and the filter mass became weighed. Attempts were made with activated, quenched coal (AS) as well as slowly cooled Coal (LA) carried out. The results are shown in Table 10. The capacity is in mg benzene / g Coal indicated.

IO

20th

1 - 3.3 318

2 160 LA 3.3 350 +! 0.0

3 160 AS 3.3 360 +13.2 *) Increase in capacity compared to the capacity of the original coal, test no. 1.

LA = Slowly Chilled Coal.
AS = quenched coal.

Example 11

Sutcliffe Speakman 206 A activated carbon was activated and cooled as described in Example 9. The coal was examined for its benzene capacity at 25 ° C. The remaining test conditions are given in Example 10, with the exception of the bed volume which was 10 ml.

4.9 g of the mentioned type of coal was at 207 "C activated and deterred. The benzene uptake was 0.835 g, corresponding to 0.204 g benzene / g carbon or 20.4% by weight benzene per gram of coal.

The original material had a benzene capacity corresponding to 0.128 g benzene / g coal with a Standard deviation ± 4.3%. The capacity increase compared to the original product! isv thus 0.076 g Benzene / g coal or 59.5%.

In Table 11 is the capacity measurement of the original coal and the coal that activated and quenched (AS) or slowly cooled.

Tabel 11 Activity
foresight
temperature Activity
foresight
procedure weight
the coal Sorbed
Benzene capacity Capacity
increase*) Ver
search-
No. C. G G g benzene /
g coal % 0.128 **) 0 1 108 AS 4.43 0.836 0.189 47.5 2 108 LA 4.57 0.667 0.146 14.0 3 207 AS 4.24 0.877 0.207 61.6 4th 207 LA 4.44 0.711 0.160 25.0 5 500 AS 4.39 0.736 0.168 31.2 6th

*) Increase in capacity compared to the capacity of the original coal. **) Average of 3 measurements.
LA = Slowly Chilled Coal.
AS = quenched coal.

Example 12

Impregnated carbon of the same type as in the example 3 was activated to 160 ° C., as also described in example 3. The cooling was done in a cooling liquid made up of solid carbon dioxide (CO2) and carbon tetrachloride. The ones in the coolant The measured temperature was -66 "C. The activated carbon was tested for its chloropicrin capacity.

The test conditions were the same as in Example 3.

A breakthrough time of 69 min. For 75 ml Carbon filter reached, corresponding to 0.92 min./ml.

Tune compilation of the tcstrcsultatc of coal, after activation with different cooling rates had cooled down. is shown in Table 12.

Table 12 Activity
foresight
procedure temperature
of cool
mediums Cooling rate capacity mg / ml Capacity
modification*) 0 Experimental
No. C. C / min. min / ml 105 % + 60.0 - - - 0.70 168 + 31.4 1 AS -196 250 1.12 138 -11.4 ι AS -66 90 0.92 93 3 LA + 20 18th 0.62 4th

*) Change in capacity compared to the capacity of the original coal, experiment no. ♦ *) Temperature range: 160 - * 0 C. LA = slowly cooled coal. AS = quenched coal.

Example 13

This example deals with the adsorption of nitrogen by ASC charcoal that has been activated and cooled several times. The coal was of the same type as in Example 1. The adsorption mechanism corresponds to the typical physical sorption including capillary condensation. Activation was carried out by heating 75 ml of carbon to 160 ° C. in a quartz glass tube for 3 hours. The charcoal was quenched in liquid nitrogen (approx. 15 min.) And warmed to room temperature. 5 g of the sample were saved for sorption measurements. The remaining coal, about 72 ml was heated again for 3 hours at 160 ⁰ C and quenched dr.nach. This activation / cooling cycle was repeated 4 times.

An apparatus was used to measure the adsorption of nitrogen by carbon (adsorption isotherms) normally used to measure the sorption isotherms of nitrogen. One such apparatus is in the publication (S. j. G regg, K. Sing. Absorption, Surface Area and Porosity, p. 314-316, 1967). The principle is that a known amount of nitrogen is poured into the Equilibrium is brought about with a known amount of adsorbent. At sorption equilibrium, the Read the equilibrium pressure. The volume and temperature of the gas phase are known. With the help of Gas law pv = nRT, the amount of N2 in the gas phase is calculated, and this is derived from the originally added amount of nitrogen removed. The difference means the amount absorbed. When increasing As the amount of gas increases, so does the equilibrium pressure and the amount of gas adsorbed.

The amount of gas adsorbed is given as ^{cmJ of} nitrogen per gram of coal. The nitrogen volume is defined at 0 "C and 760 mm I Ig.

55.6 mg of charcoal, which was 3 times activated and been quenched, was evacuated for 3 hours at 25 ° C up to a pressure of 2 x 10 ~ ⁴ mm Hg. The samples are then cooled to -196 "C and refilled with nitrogen until an equilibrium pressure of 490 mm Hg was reached.

This corresponds to a relative equilibrium pressure

762

= 0.65.

Po = measured vapor pressure of the liquid nitrogen at the existing (measured) atmospheric pressure. The amount of N2 adsorbed was 278 cmVg char. The original product had an N2 uptake of 255 cmVg carbon at the same relative equilibrium pressure. The activated charcoal samples have thus experienced a capacity increase of 13 cm ³ nitrogen / g charcoal, corresponding to 9.0%.

Example 14

In the following examples, reference is made to the increase in sorption of coal which can be up to Activated and quenched 4 times as described in Example 13. The samples are of the same Type of coal as described in Examples 1 and 13.

• n The samples were pretreated (evacuated) and measured in the same way as described in Example 13. The amount of Nj adsorbed was measured at various equilibrium pressures.
The results of the measurements are shown in Table 13

■> [) shown.

In the table is the relative equilibrium pressure ρ
"-Specified. The table shows that one

by increasing the number Aklivierungs-ZAbschreck- Vi processes an increase of the sorption achieved. The increase is greatest at low relative pressure.

At a relative pressure of 5- = 0.98, the im

"0

We generally assumed that the adsorbed nitrogen is in a condensed state. In practice this means that the total pore volume with liquid Is filled with nitrogen. The adsorbed gas volume can by multiplying it into liquid N2 volume

hi to be converted.

The percentage of the capacity increase achieved therefore also expresses a corresponding increase in the entire pore volume.

19th

Table 13

Test number Relative adsorbed capacity Note

No. Quenching equilibrium amount N? increasing

process pressure

1
2
3
4th
5

10

11
12th

13th
14th
15th

16
17th
18th
19th
20th

0 1 2 3 4

0 1 2 3 4

ü 1 2 3 4

1 2 3 4

P. cm ^J / g bull 0 Pooh + 3.6 0.20 219 + 10.0 0.20 227 + 10.0 0.20 241 + 15.5 0.20 241 0 0.20 253 2.8 0.40 244 8.0 0.40 251 9.1 0.40 264 12.7 0.40 267 0 0.40 276 0.7 0.65 255 7.8 0.65 257 9.0 0.65 275 9.8 0.65 278 0 0.65 280 5.1 0.98 293 7.4 0.98 308 8.8 0.98 315 10.9 0.98 319 0.98 325 Example 15

Original product

Original product

Original product

Original product

This example demonstrates the sorption effect as a result of the activation and the repeated quenching process in liquid nitrogen with regard to the impregnated ASC activated carbon of the same type as mentioned in Example 3. Chloropicrin was used as the sorbing gas. 1.75 l / min. Air containing 5 mg chloropicrin / l was passed through a filter made of said activated carbon. This corresponds to a picrine dosage of 8.75 mg / min. The samples were activated in ^ atmosphere for 3 hours at 170 ⁰ C and then quenched in tubes, which were surrounded by liquid nitrogen. The filter temperature was 25 ° C. The filter area measured 2.40 cm ^J. It took 35 minutes for the gas to break through, giving a capacity of 76.5 mg / ml charcoal

■ represents n. The original coals not activated had a capacity representing 61.2 mg / ml charcoal.

The capacity increase is therefore 25.0%. The results after repeated activations are in Table 14 shown. From Table 14 it can be seen that

-) (> an increased number of activation and deterrence processes causes an increase in the sorption capacity.

Tabel 14th By capacity Capacity Ver number of fracture valid search- Activity Time taking *) No. struggles Min. mg / ml charcoal % 61.2 0 1 original 35 76.5 25.0 2 1 36 78.6 28.4 3 2 37 81.0 32.3 4th 3 39 85.0 38.8 5 4th

*) Increase in capacity compared to the capacity of the original coal, experiment No. 1.

Example 16

This example documents the increase in chemical sorption of SO2 by K ₂ COrim-impregnated coal of the type "Dräger E 900".

11.0 g of carbon, which had been _{activated for 3 hours in an N 2} atmosphere and then quenched in a quartz tube surrounded by liquid nitrogen, was tested for its SO 2 capacity.

3.34 l / min, an SO ₂ -air mixture, which contained 0.39 vol .-% SO2, was passed through a filter of activated charcoal. The filter mass had a volume of 22 ml and a bed diameter of 2.2 cm. The linear gas velocity through the filter was 0.146 m./sec., The feed temperature was 25 ° C.

The breakthrough of SO2 was registered at a concentration of 0.014% by volume SO ₂ in the gas. A thermal conductivity detector was used for this purpose.

At the breakthrough, the coal had absorbed 240 mg of SO2. This corresponds to an SO ₂ capacity of 0.0218 gSO ₂ / g coal.

The original coal had a capacity corresponding to 0.0199 gSO ₂ / g coal.

The capacity increase is thus 9.6%.

Example 17

This example demonstrates the increase in the SO: capacity of impregnated charcoal, which at activated at various temperatures (up to 290 ° C) and quenched in liquid nitrogen (AS).

The coals are of the same type as described in Example 16: so are the test conditions.

Tabel 15th Activity Activation capacity Capacity _ Ver foresight foresight modification + 9.6 search- temperature to betray + 1.5 No. I. mgSO ₂ / % + 12.1 g coal -3.0 19.9 + 107.5 1 115 AS 21.8 + 64.5 2 115 LA 20.2 + 34.4 3 150 AS 22.3 4th 150 LA 19.3 5 265 AS 41.3 6 *) 265 LA 32.8 7 *) 300 AS 26.8 8th

*) Due to the intensive course of the reaction in the air stream, the SOi uptake was carried out in a nitrogen atmosphere.

Example 18

Coal granules of the Sutcliffe Speakman 607 type were, as described in Example 10, ^{heated to 160 °} C. and then quenched. The granulate was tested for benzene capacity at 90 ° C. An air stream (265 cmVmin.) Saturated with benzene vapor (4.23% by volume) was passed through a filter with a volume of 10 cm ³ . The remaining dimensions of the filter were the same as in Example 10, with the exception of the bed height. The benzene uptake was checked by weighing the granules before and after the benzene breakthrough. The breakthrough is defined at the point in time at which the benzene concentration in the outflowing air had reached 0.11% by volume. A thermal conductivity detector was used for this purpose.

The results are shown in Table 16.

Table 16 Activation
procedure weight
the Kohie
G Sorbed
Benzene
lot
mg capacity
g benzene Capacity
increase*)
% Experimental
No. g coal original
LA
AS 4.07
4.10
4.10 504
660
762 123.8
161.0
186.0 0
+ 30.1
+ 50.2 1
2
3

*) Change in capacity compared to the capacity of the original coal, experiment no. 1. LA - Slowly cooled coal.
AS = quenched coal.

1 sheet of drawings

Claims (5)

Patent claims: 1. A method for improving the sorption capacity of activated carbon by heating and subsequent quenching by means of a cooling medium, characterized in that the carbon is first ^{heated in an inert atmosphere to a temperature in the range 50-300 0} C and then by cooling in indirect heat exchange up to one Temperature of less than -66 ⁰ C is quenched. 2. The method according to claim 1, characterized in that the quenching in inert Atmosphere takes place 3. The method according to claim 1, characterized in that that the quenching takes place at a cooling rate of 90-400 ° C / min down to 0 ° C 4. The method according to claim 1, characterized in that the cooling is combined with the condensation of an incoming inert gas due to the Joule / Thompson effect. 5. Apparatus for performing the method according to one or more of claims 1 to 4 with a tube furnace for heating the activated carbon and a cooling chamber arranged therebelow, which can be closed against the tube furnace with a shut-off element, with a partition between activated carbon and cooling medium, characterized in that the cooling chamber (D) is ring-shaped and is arranged with inner and outer walls in a cooling medium container (E, F,).