CA2138376A1 - Activated carbon by treatment of lignites with potassium and/or sodium hydroxide or salts and adsorption therewith - Google Patents
Activated carbon by treatment of lignites with potassium and/or sodium hydroxide or salts and adsorption therewithInfo
- Publication number
- CA2138376A1 CA2138376A1 CA002138376A CA2138376A CA2138376A1 CA 2138376 A1 CA2138376 A1 CA 2138376A1 CA 002138376 A CA002138376 A CA 002138376A CA 2138376 A CA2138376 A CA 2138376A CA 2138376 A1 CA2138376 A1 CA 2138376A1
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- Canada
- Prior art keywords
- activated carbon
- set forth
- lignite
- potassium
- brown coal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/312—Preparation
- C01B32/342—Preparation characterised by non-gaseous activating agents
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Carbon And Carbon Compounds (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Abstract
Activated carbons for the adsorption of vapors, gases and liquids for a variety of appli-cations prepared from a dry lignite or brown coal treated with at least one of potassium hy-droxide and/or salts thereof and/or sodium hydroxide or salts thereof which are charred and thereafter activated. These activated carbons have increased hexane working capacity of at least 5.4 %.
Description
wo 94/00382 2 ~ 3 ~ 3 7 6 PCr/US93/os804 TITLE
"Activated Carbon By Treatment of Lignites With Potassium and/or Sodium Hydroxide Or Salts And Adsorption Therewith"
FIELD OF THE INVENTION
The present invention relates to improved activated carbon for adsorption of organic vapors, gases or vapors, using potassium and sodium hydroxide or potassium and sodium salts so as to achieve an activated carbon with increased working capacity, lower apparent density and increased capacity for the removal of gases, vapors and liquids.
BACKGROUND OF THE INVENTION
The present invention involves the manufacture i5 of activated carbons from inexpensive lignite (brown coal) to achieve superior adsorptive working capacity and other desirable attributes in the improved adsorptive material.
These activated carbons are useful in removing, adsorbing or storing organic gases, vapors and liquids;
specific uses include, but are not limited to, evaporative loss control canisters on automobiles, in-line filters, solvent recovery filters and other applications. For example, when activated carbon is used in evaporative loss canisters on automobiles, the activated carbon should have the highest possible hydrocarbon working capacity and the lowest possible apparent density. Activated carbon SUBSTITUTE SHEET
W094/00382 PCT/US93/ ~ ~
~8~76 formulations that include the use of potassium impregnation before activation for these purposes are known; however, known formulations lack desirable (working) adsorptive capacity, may require the use of more adsorptive material than is desirable in many applications, and/or may be expensive to produce. In the case of carbon filters or beds to be used in evaporative control devices in vehicular fuel systems, the drawbacks associated with such known fuel vapor control carbons can be significant.
The activated carbons of the present invention may also involve the further use of special impregnants to remove gases, vapors and li~uids that would not otherwise be removed through the use of unimpregnated activated carbons.
Attempts have been made to enhance the properties of activated carbons using potassium ions. For example, in German Publication No. 3,834,745 to Karl, moist brown coals are impregnated with potassium. The activated carbons in Karl are produced by heating or steam activating moist brown (unprocessed) coals that are impregnated with KOH before activation. Karl discloses the use of carbons with moisture levels of about 46-593 and KOH levels up to about 2%. Activated carbons with iodine adsorptivity of 600-1100 mg/g were produced with brown coal at a final activation yield of about 14% (dry basis). Also, U.S. Patent No. 4,039,473 to Schafer describes a carbon ~lignite) that is treated with potassium, charred and leached (to remove the potassium), and optionally steam-activated to achieve additional activity.
The shortcomings of these and other kno~
carbons are easily understood; they may require more space, in that they have less adsorptive working capacity SUBSTITUTE SHEET
~ 094/00382 2 1 38 3 1~ PCT/US93/05804 per unit volume. As minimum fill volumes must be used to meet the required size and weight restrictions in fue evaporative loss control canisters and other applications, the activated carbon must have very high working capacities per unit volume.
Using lignites (brown coal), the present invention results in activated carbons having an improved and unique pore structure which yields superior working capacity resulting in a more effective carbon that results in cost, weight and space savings. By using a lower cost feed stock (lignite), the present invention results in an immediate cost savings.
Accordingly, the present invention is intended to provide a more effective, more compact, and less expensive activated carbon that is effective in removing and/or storing gases and/or vapors, and liquids for use in automotive and industrial applications. The potassium and/or sodium hydroxides and salts thereof used for the treatment of the lignites (brown coals) of the present invention are applied prior to charring and activation in an efficient, reliable and cost-effective manner.
SUM~ARY OF THE INVENTION
The present invention comprises an activated carbon manufactured from lignite (brown coal) by impregnating a lignite with a solution of potassium andjor sodium hydroxide or salt thereof followed by charring and thereafter activation. For the purpose of the present invention, the terms "lignite" and "brown coal" are low-rank coals having an oxygen content greater than from about 15 to 17% up to about 30%. The present invention solves the problem of the required use of more expensive carbons, as it achieves improved performance by using SUESTITUTE SHEET
W094/00382 - - PCT/US93/ ~ ~
~38376 potassium and/or sodium hydroxide and/or salts thereof on relatively inexpensive feed stock. Further, the carbons of the present invention attain greater hydrocarbon working capacities, lower apparent densities and increased hydrocarbon capacities. The activated carbons of the present invention have improved and unique pore structures, which yield superior working capacities; these carbons yield cost savings, environmental benefits and superior performance.
The carbons of the present invention can be significantly less expensive to produce, and have greater working capacities than known carbons produced from known KOH impregnated carbonaceous materials, to include known steam activated wood-based pellet carbons, or brown coals and pit-wet lignites impregnated with KOH before activation.
One commercial wood-base carbon was found to have a gasoline working capacity of 34 9/1. A brown coal carbon was found to have a gasoline working capacity of 29.4 9/l. The carbon present invention can achieve gasoline working capacities greater than 57.0 g/l. The activated carbons of present invention can thererore achieve an increase in working capacity of at least 91%
over the aforementioned brown coal carbon and at least 6 over the aforementioned wood-base carbon. The wood-based carbon is a more expensive material and is less effective than the lignite (brown coal) based carbons of the preser.t invention. The known brown coal or pit-wet lignite substitute, on the other hand, is "heavy" to ship due to its high water content and produces less effective activated carbon.
Due to the increased working capacities of the activated carbons of the present invention, less carbcn filter material is required to achieve the same working ~;UB8TITUTE SHEET
~ 0 94/00382 2 1 3 8 3~ PC~r/US93/05804 capacities of less adsorptive carbons. Significant cost savings can be achieved using smaller canisters filled with activated carbons of the present invention.
The activated carbons of the present invention also avoid unnecessary excess weight of pit-wet material, and provides for processing equipment advantages. The product of the pres~ént invention may be granulated, pelletized or "shaped" into other forms without a binder via (most desirably) pressure formation, or prepared with a binder.
The process of the present invention is effective in an expanded range of carbonaceous material compositions, treated prior to charring and activation with potassium or sodium. The amount (by weight) of potassium or sodium hydroxide or salts thereof present on the carbon after charring and activation can increase, for example double, due to carbon shrinkage following activation. The formulations may be varied, depending on the particular application and/or performance characteristics desired.
However, preferred embodiments of the present invention comprise a low-rank coal, preferably a lisnite, treated prior to charring and activation to provide a composition containing, by weight, up to about 30%
potassium (as KOH or an equivalent potassium salt). Up tc about 120% water may also be used. This potassium or sodium hydroxide or salt thereof can be effectively dispersed over agglomerated lignite granules (8x30, 6x20, 12x30, and other mesh sizes), or any similar carbonaceous media. The apparent density of the carbons of the present invention are desirably less than 370 g/l, and have a high hexane working capacity (defined hereinafter) of at least 5.4%.
SUBSTITUTE SHEET
-W094/00382 PCT/US93/ ~ 1 2~L3~3~6 A specific preferred embodiment of the present invention comprises lignite (brown coal) treated with about 5~ potassium (KOH) and 25% water prior to charring and activation.
The activated carbons of the present invention have a wide-range of utility and provide balanced performance. For certain applications, such as in automotive applications, the activated carbons provide high working capacities which can be regenerated by passage of ambient air over the carbon. Other advantages of the activated carbons of the present invention will become apparent from a perusal of the following detailed description of presently preferred embodiments taken in connection with the accompanying drawings.
BRIEF DESCRIPTIONS OF THE DRAWINGS
Figure 1 is a flow diagram of the process of the present invention for manufacturing pelletized activated carbon;
Figure 2 is a flow diagram of the process of the present invention for manufacturing a nonagglomerated granular activated carbon; and Figure 3 is a flow diagram of the process of the present invention for manufacturing an agglomerated granular activated carbon.
PRESENTLY PRE~ERRED EMBODIMENTS
The present invention is directed to the manufacture of activated carbons from lignites (brown SUBSTITU~E ~IEET
0 94/00382 ~ 1 3 8 ~ 7~ PC~r/US93/05804 coals) having increased surface area and superior working capacities for the adsorption of hydrocarbons and other gases, vapors and liquids. Activated carbons prepared according to the present invention are superior adsorbents for evaporative loss control canisters, solvent recovery and other applications.
The process of the present invention is effective in using a broad range of potassium or sodium hydroxides and/or salts thereof treatment compositions.
These formulations may be varied, depending on the particular application and/or performance characteristics desired for the activated carbon.
A number of process parameters have been found to affect the performance of the carbon product. These parameters include: (1) the particular potassium or sodium hydroxide or salt used, the level of these hydroxides and salts, and the source from which these hydroxides or salts are obtained; (2) the method of hydroxide and salt treatment of the lignite (brown coal);
"Activated Carbon By Treatment of Lignites With Potassium and/or Sodium Hydroxide Or Salts And Adsorption Therewith"
FIELD OF THE INVENTION
The present invention relates to improved activated carbon for adsorption of organic vapors, gases or vapors, using potassium and sodium hydroxide or potassium and sodium salts so as to achieve an activated carbon with increased working capacity, lower apparent density and increased capacity for the removal of gases, vapors and liquids.
BACKGROUND OF THE INVENTION
The present invention involves the manufacture i5 of activated carbons from inexpensive lignite (brown coal) to achieve superior adsorptive working capacity and other desirable attributes in the improved adsorptive material.
These activated carbons are useful in removing, adsorbing or storing organic gases, vapors and liquids;
specific uses include, but are not limited to, evaporative loss control canisters on automobiles, in-line filters, solvent recovery filters and other applications. For example, when activated carbon is used in evaporative loss canisters on automobiles, the activated carbon should have the highest possible hydrocarbon working capacity and the lowest possible apparent density. Activated carbon SUBSTITUTE SHEET
W094/00382 PCT/US93/ ~ ~
~8~76 formulations that include the use of potassium impregnation before activation for these purposes are known; however, known formulations lack desirable (working) adsorptive capacity, may require the use of more adsorptive material than is desirable in many applications, and/or may be expensive to produce. In the case of carbon filters or beds to be used in evaporative control devices in vehicular fuel systems, the drawbacks associated with such known fuel vapor control carbons can be significant.
The activated carbons of the present invention may also involve the further use of special impregnants to remove gases, vapors and li~uids that would not otherwise be removed through the use of unimpregnated activated carbons.
Attempts have been made to enhance the properties of activated carbons using potassium ions. For example, in German Publication No. 3,834,745 to Karl, moist brown coals are impregnated with potassium. The activated carbons in Karl are produced by heating or steam activating moist brown (unprocessed) coals that are impregnated with KOH before activation. Karl discloses the use of carbons with moisture levels of about 46-593 and KOH levels up to about 2%. Activated carbons with iodine adsorptivity of 600-1100 mg/g were produced with brown coal at a final activation yield of about 14% (dry basis). Also, U.S. Patent No. 4,039,473 to Schafer describes a carbon ~lignite) that is treated with potassium, charred and leached (to remove the potassium), and optionally steam-activated to achieve additional activity.
The shortcomings of these and other kno~
carbons are easily understood; they may require more space, in that they have less adsorptive working capacity SUBSTITUTE SHEET
~ 094/00382 2 1 38 3 1~ PCT/US93/05804 per unit volume. As minimum fill volumes must be used to meet the required size and weight restrictions in fue evaporative loss control canisters and other applications, the activated carbon must have very high working capacities per unit volume.
Using lignites (brown coal), the present invention results in activated carbons having an improved and unique pore structure which yields superior working capacity resulting in a more effective carbon that results in cost, weight and space savings. By using a lower cost feed stock (lignite), the present invention results in an immediate cost savings.
Accordingly, the present invention is intended to provide a more effective, more compact, and less expensive activated carbon that is effective in removing and/or storing gases and/or vapors, and liquids for use in automotive and industrial applications. The potassium and/or sodium hydroxides and salts thereof used for the treatment of the lignites (brown coals) of the present invention are applied prior to charring and activation in an efficient, reliable and cost-effective manner.
SUM~ARY OF THE INVENTION
The present invention comprises an activated carbon manufactured from lignite (brown coal) by impregnating a lignite with a solution of potassium andjor sodium hydroxide or salt thereof followed by charring and thereafter activation. For the purpose of the present invention, the terms "lignite" and "brown coal" are low-rank coals having an oxygen content greater than from about 15 to 17% up to about 30%. The present invention solves the problem of the required use of more expensive carbons, as it achieves improved performance by using SUESTITUTE SHEET
W094/00382 - - PCT/US93/ ~ ~
~38376 potassium and/or sodium hydroxide and/or salts thereof on relatively inexpensive feed stock. Further, the carbons of the present invention attain greater hydrocarbon working capacities, lower apparent densities and increased hydrocarbon capacities. The activated carbons of the present invention have improved and unique pore structures, which yield superior working capacities; these carbons yield cost savings, environmental benefits and superior performance.
The carbons of the present invention can be significantly less expensive to produce, and have greater working capacities than known carbons produced from known KOH impregnated carbonaceous materials, to include known steam activated wood-based pellet carbons, or brown coals and pit-wet lignites impregnated with KOH before activation.
One commercial wood-base carbon was found to have a gasoline working capacity of 34 9/1. A brown coal carbon was found to have a gasoline working capacity of 29.4 9/l. The carbon present invention can achieve gasoline working capacities greater than 57.0 g/l. The activated carbons of present invention can thererore achieve an increase in working capacity of at least 91%
over the aforementioned brown coal carbon and at least 6 over the aforementioned wood-base carbon. The wood-based carbon is a more expensive material and is less effective than the lignite (brown coal) based carbons of the preser.t invention. The known brown coal or pit-wet lignite substitute, on the other hand, is "heavy" to ship due to its high water content and produces less effective activated carbon.
Due to the increased working capacities of the activated carbons of the present invention, less carbcn filter material is required to achieve the same working ~;UB8TITUTE SHEET
~ 0 94/00382 2 1 3 8 3~ PC~r/US93/05804 capacities of less adsorptive carbons. Significant cost savings can be achieved using smaller canisters filled with activated carbons of the present invention.
The activated carbons of the present invention also avoid unnecessary excess weight of pit-wet material, and provides for processing equipment advantages. The product of the pres~ént invention may be granulated, pelletized or "shaped" into other forms without a binder via (most desirably) pressure formation, or prepared with a binder.
The process of the present invention is effective in an expanded range of carbonaceous material compositions, treated prior to charring and activation with potassium or sodium. The amount (by weight) of potassium or sodium hydroxide or salts thereof present on the carbon after charring and activation can increase, for example double, due to carbon shrinkage following activation. The formulations may be varied, depending on the particular application and/or performance characteristics desired.
However, preferred embodiments of the present invention comprise a low-rank coal, preferably a lisnite, treated prior to charring and activation to provide a composition containing, by weight, up to about 30%
potassium (as KOH or an equivalent potassium salt). Up tc about 120% water may also be used. This potassium or sodium hydroxide or salt thereof can be effectively dispersed over agglomerated lignite granules (8x30, 6x20, 12x30, and other mesh sizes), or any similar carbonaceous media. The apparent density of the carbons of the present invention are desirably less than 370 g/l, and have a high hexane working capacity (defined hereinafter) of at least 5.4%.
SUBSTITUTE SHEET
-W094/00382 PCT/US93/ ~ 1 2~L3~3~6 A specific preferred embodiment of the present invention comprises lignite (brown coal) treated with about 5~ potassium (KOH) and 25% water prior to charring and activation.
The activated carbons of the present invention have a wide-range of utility and provide balanced performance. For certain applications, such as in automotive applications, the activated carbons provide high working capacities which can be regenerated by passage of ambient air over the carbon. Other advantages of the activated carbons of the present invention will become apparent from a perusal of the following detailed description of presently preferred embodiments taken in connection with the accompanying drawings.
BRIEF DESCRIPTIONS OF THE DRAWINGS
Figure 1 is a flow diagram of the process of the present invention for manufacturing pelletized activated carbon;
Figure 2 is a flow diagram of the process of the present invention for manufacturing a nonagglomerated granular activated carbon; and Figure 3 is a flow diagram of the process of the present invention for manufacturing an agglomerated granular activated carbon.
PRESENTLY PRE~ERRED EMBODIMENTS
The present invention is directed to the manufacture of activated carbons from lignites (brown SUBSTITU~E ~IEET
0 94/00382 ~ 1 3 8 ~ 7~ PC~r/US93/05804 coals) having increased surface area and superior working capacities for the adsorption of hydrocarbons and other gases, vapors and liquids. Activated carbons prepared according to the present invention are superior adsorbents for evaporative loss control canisters, solvent recovery and other applications.
The process of the present invention is effective in using a broad range of potassium or sodium hydroxides and/or salts thereof treatment compositions.
These formulations may be varied, depending on the particular application and/or performance characteristics desired for the activated carbon.
A number of process parameters have been found to affect the performance of the carbon product. These parameters include: (1) the particular potassium or sodium hydroxide or salt used, the level of these hydroxides and salts, and the source from which these hydroxides or salts are obtained; (2) the method of hydroxide and salt treatment of the lignite (brown coal);
(3) the process used to char the lignite (brown coal):
(4) the process used to activate the carbon; (5) the procedure used to dry and/or wash the activated carbon;
(6) the amount of moisture present or added at each step;
and (7) the activity of the starting lignite (~rown coal).
Other parameters also affect the final characteristics of the activated carbon of the present invention, but to a lesser extent.
Tests were performed to provide a description of the unique qualities of activated carbons of the present invention. Also, preferred methods of preparing the activated carbons are set forth. It has been found, for example, that Australian lignite (brown coal) produced carbons with good hexane adsorption and working capacities. It has also been found that other lignites SUBSTITUTE SHEET
W094/00382 PCT/US93/ ~
2~38~6 produce exceptionally good working capacities. In these tests, the lignite (brown coal) was treated with a solution of KOH, charred in an inert atmosphere and activated with steam.
Initial preparation comprises pulverizing the dry lignite (brown coal) and then treating it with a solution of KOH and, thereafter, forming it into two-millimeter pellets. This procedure maximizes the advantages of the potential interaction between KOH and oxygenated surface groups of lignite (brown coal) for the present invention. These pellets were charred in an inert atmosphere and activated in steam. This preferred method of treating the lignite with KOH prior to charring yielded surprisingly desirable results.
i5 In preliminary tests, two-millimeter pellets were formed from lignite (brown coal) with a 2.5% KO~
loading. The pellets were air-dried for three days, charred in nitrogen at 700C, and activated in steam at 870-950C. About 20 to 25 mg of activated carbon were pllt in a micro balance and were kept at constant temperature of 30C. A stream of 100 ml/minute of pure nitrogen saturated with n-hexane at 0C was passed through the carbon for 20 minutes. Then a stream of 100 ml/minute of pure nitrogen was passed through the carbon saturated with hexane f~r 20 minutes. The difference in weights of the carbon is defined as the hexane working capacity.
Hexane capacity and working capacity of pellets that were activated in the range of 870-900C reachec approximately 42-45% and 13-14~, respectively. Butane capacity and working capacity reached approximately 36-~6~
and 22-24%, respectively. This butane capacity range is higher than the highest capacity of the known commercial SUBSTITUTE SHEET
2138~
. .
_g_ carbons ( WVA1100~ with 34%). Therefore, the treatment of dry lignite (brown coal) with KOH prior to charring resulted in an activated carbon having a large adsorption capacity and a high working capacity.
Different levels of potassium hydroxide or salt treatment and charring temperatures were studied to produce optimal working capacity. Tests were run on Australian lignite (brown coal) pellets with up to 30% KOH
(by weight). A hexane working capacity of 20% was achieved using this level of KOH impregnation.
These test led to products made with 5% KOH
having a variety of highly desirable characteristics, particularly for use in gas phase applications such as evaporative loss control canisters, solvent recovery, and others. Although lignites (brown coal) impregnated with 2.5% and 1.25% KOH resulted in activated carbons useful for some applications, the 5.0% level of KOH resulted in carbons with higher activity. Carbons at the 2.5% KOH
level show greater butane working capacities than 1.25%
KOH carbons. Potassium hydroxide catalyzed activation of lignite (brown coal), both in granular agglomerated and sized nonagglomerated forms, resulted in activated carbor.s with good hexane capacities and working capacities.
Further samples of the lignite (brown coal) were treated with a solution of KOH, and thereafte.
agglomerated into 6x20 mesh granular form or sized into 8x30 mesh directly then charred in a nitrogen atmosphere at ?o0C for 10 minutes. The char was then activated in steam. Flow diagrams for the preparation of three forms of activated carbon of the present invention are shown in Pigures 1, 2 and 3.
Westvaco Corporation.
SUBSTITUTE S~EET
W094/00382 ~ ~ ~ 837 ~ PCT/US93/ ~ 4 To achieve an enhanced pore structure, KOH
solution was sprayed into the pulverized lignite to a KOH
loading of 5%. The wet mixture of coal and KOH was pelletized without further addition of any binder to form 2mm pellets. The wet pellets were charred in a nitrogen atmosphere at 700C for 10 minutes. It was discovered that by reducing the steam delivery rate and by diluting the activation gas with nitrogen, hexane working capacity was increased dramatically and increased the yield of the carbon. Hexane working capacity was 20.5%.
In further tests, KOH loading of 5.2% in the char feedstock produced the activated product with hexane capacity reaching approximately 45% at activation temperatures of 870-900C. The hexane working capacity of these products reached approximately 13-14%. (The hexane capacity and hexane working capacity are approximately 32%
and 17%, respectively for a first commercially used carbon and 44% and 20%, respectively for a second commercially used carbon).
Further tests were performed using pulverizeà
dry lignite (brown coal) having a water content of 1~.4%
mixed with a solution consisting of 25% (by weight of lignite) water and 5% (by weight of lignite) potassium hydroxide. The mixture was agglomerated, crushed, and screened to 8x30 mesh. This granular material was charred under an inert atmosphere at 800C for 20 minutes. The char was activated in a steam atmosphere at 870C to produce activated carbons of the present invention.
Superior activated carbons were produced by this process;
a first sample activated for 230 minutes had a hexane working capacity of 17.7%, and a second example activated for 250 minutes had a hexane working capacity of 22.1%.
The activated carbon of the preser.. invention using lignites (brown coal) has an apparent density as low SUBST~TUTE SHEET
2138~6 ~ 0 94/00382 PC~r/US93/05804 as 250 9/1 or lower. These surprising low densities are partly responsible for the superior perfarmance. These attributes of surprisingly low apparent density and superior hexane working capacity provide an activated carbon which is remarkably effective as an adsorbent for a large range and number of applications.
Of the various treatment methodologies available, the most reliable method is treatment of the lignite (brown coal) by spraying with a solution of the hydroxide or salt. Methods of preparation may include one, two or more treatment cycles with the selected hydroxide or salt(s) by spraying, wetting or other process, In producing the carbons of the present invention, the constituents should preferably be applied to the lignite (brown coal) using a single application.
The resulting mixture may thereafter be, as desired or necessary, thermally processed by charring and steam activation into the desired activated carbon product. In addition to this single application method, a method involving a second application (by solution or spray operation) can also be used to achieve the desired hydroxide or salt loadings. This two-step application can also be used to achieve uniform high hydroxide or sa t loadings, or application of different liquids than those applied during the first loading.
Pormulations containing various loadings of potassium or sodium hydroxide or salts thereof on granular, pelletized, and other shaped carbonaceous particles of differing mesh sizes will likewise desirably perform. Low-moisture content (e.q., less than 20% by weight) of the lignite (brown coal) prior to charrinq and was discovered to be a factor in enhancing the performance ~t~2ff;~the carbons after activation.
SUB~TIT~TE SHEET
~A21 38376 Numerous examples of lignites (brown coals) were prepared in accordance with the present invention and tested. The results of these tests are described in Table 1.
TABLE I
Startlng ImpreDnan~ Cbarrlng Adivation Apparcnt HeJran~ Butano Test Number Form Materlal Type Levol Temporatur~ remperatur~ Density Capacity Working Capacity Working-(% by V~U (C) (Ci lg/oc) (X) Capacity (X) Capacity 1%) (S6) Z90143-1 Pellot Au~trallanù.c. KOH 5.0 500 900 0.306 37.5 9.0 31.3 17.8 290143-Z Pellet Australian b.c. KOH 5.0 500 900 0.299 39.2 10.9 35.8 21.1 1 0 290143-3 Pellut Australianb.c. KOH 5.0 500 900 0.281 44.6 11 8 31.6 20.4 2901-14-5 Pellet Australian b.c. KOH 5.0 800 870 0.321 33.7 9.9 30.2 18.1 2901-15-1 Pellot Australianb.c. KOH 5.0 600 870 0.313 35.7 11.7 28.1 18.8 2901-17-1 Pellet Australian b.c. KOH 5.0 600 900 0.325 32.7 9.7 25.7 15.6 2901-15-5 Pellet Australlanb.c. KOH 5.0 ûO0 900 0.310 37.5 9.ff 27.2 17.3 1 5 2891-58-2 Pellot Australianbc KOH 50 700 870 0.343 30.0 8.7 28.8 16.1 2891-58-3 Pellot Australianb.c. KOH 5.0 700 870 0.341 35.9 10.1 29.4 17.1 2891-56-4 Pellet Australianb.c. KOH 5.0 700 900 0.326 35.7 10.5 26.0 16.8 2891-57-1 Pollot Australianb.c. KOH 5.0 700 900 0.316 42.0 12.7 29.6 21.1 2891-65-1 Pellet Australianb.c. KOH 5.0 700 950 0.319 39.0 10.8 27.1 17.0 2891-85-4 Pellet Australianb.c. KOH 5.0 700 950 0.293 37.6 10.6 29.2 18.9 2904-48-4 Pellet Australian b.c. KOH 2.5 800 870 0.338 - - 30.5 16.4 2904-48-2 Pellet Australianb.c. KOH 2.5 800 950 0.307 - - 31.1 19.7 2904-50-1 Pellet Australlan b.c. KOH 2.5 700 870 0.304 - - 29.8 16.4 2904-49-5 Pellet Australian b.c. KOH 2,5 700 950 0.281 - - 29.5 19.0 2904-37-3 Pellet Australianb.c. KOH 2.5 700 900 0.329 - - 30.7 18.7 2904-374 Pellet Austraiian b.c. KOH 2.5 700 900 0.310 - - 40.0 22.6 2904-38-1 Pellet Australian b.c. KOH 2.5 700 900 0276 - - 31.4 25.3 2880-20-2 Pellet Australlan b.c. KOH 1.25 700 840 0.344 18.1 6.2 2880-13-2 Pellet Australian b.c. KOH 1.25 700 870 0.333 26.7 9.5 2880-14-2 Pellet Australianb.c. KOH 125 700 900 0.329 22.2 7.0 1880-15-1 Pellet Australianb.c. KOH 1.25 700 900 0.294 293 10.3 * About 20 to 25 mg of activated carbon were put in a micro balance and were kept at constant temperature of 30C. A stream of 100 ml/minute of pure butane was passed through the carbon for 15 minutes. Then a stream of 100 ml/minute of pure nitrogen was passed through the carbon saturated with butane for 20 minutes. The difference in weights of the carbon is defined as the butane working capacity.
r~.2 1 3~376 TABLE I (continued) StartinD Impregnant Charring Adivation Apparent Hexane Butane Test Form Materlal Type Level Temperature Temperature Density Capacity Working Capacity Working Number (% by wU (C) (C) (a/oc) (%) Capacity (%) Capacity (%) (%) 2921-10-3 Pellet German b.c. KOH 5.0 800 820 - 32.6 14.3 25.2 17.3 292149-5 Pellct German b.c. KOH 5.0 800 885 0.337 35.8 12.0 30.7 19.5 292149-1 Pellut German b.c. KOH 5.0 800 885 0.359 38.0 14.6 Z8.0 18.2 292149-7 Pellet German b.c. KOH 5.0 800 950 0.338 32.9 12.2 27.3 17.4 292149-8 Pellet German b.c. KOH 5.0 800 950 0.321 41.8 16.0 27.0 17.4 1 0 2921-11-6 Pellet German b.c. KOH 5.0 800 950 0.296 42.3 16.3 30.5 19.9 2912-12-1 Pellet German b.c. KOH 5.0 800 950 0.299 39.4 14.9 19.3 16.0 2921-12-2 Pellet German b.c. KOH 5.0 800 950 0.303 44.7 16.8 33.9 21.3 2921-13-2 Pellet German b.c. KOH 5.0 800 950 0.299 46.9 18.4 349 21.6 2921-13-1 Pellet German b.c. KOH 5.0 800 950 0.280 46.4 18.7 33.1 20 9 1 5 2921-29-7 Pellet Gorman b.c. KOH 5.0 800 950 0.273 45.8 20.5 30.4 20.0 2921-33-2 Pellet German b.c. KOH 5.0 800 950 0.293 42.6 19.9 29.9 19.5 2921-33-3 Gran.UnaEigl German b.c. KOH 5.0 800 950 0.240 53.8 22.7 39.4 26.3 2921-33-4 Gran.Unaagl Genman b.c. KOH 5.0 800 950 0.252 52.2 22.2 36.4 24.0 2921-33-5 Gran.Unagçil German b.c. KOH 5.0 800 950 0.247 55.9 22.8 37.3 24.7 20 2921-37-1 Gran.Unaggl German b.c. KOH 5.0 800 950 0.246 51.6 20.7 36.9 24.3 2921-76-8 Gran.aDsl Gorman b.c. KOH 2.5 800 950 0.278 46.9 17.6 39.3 26.5 2921-76-4 Gran.aDDI German b.c. KOH 2.5 800 950 0.269 52.4 22.1 38.1 28.0 2921-76-7 Gran~aDDl German b.c. KOH 2.5 800 950 0.309 44,5 15.6 34.7 23.6 2921-82-1 Gran.aDDI German b.c. KOH 5.0 800 950 0.303 56.5 25.4 39.3 26.3 2 5 2921-82-2 Gran.aggl German b.c. KOH 5.0 800 950 0306 53.9 22.2 34.3 23.4 2921-82-3 Gran~aDDI German b.c. KOH 5.0 800 950 0.315 52.4 21.5 37.1 21.9 2950-14-1 Gran.aDDI German b.c. KOH 5.0 800 870 0.357 53.1 21.3 2950-14-2 Gran.agDI German b.c. KOH 5.0 800 870 0.338 54 6 22.2 2950-14-3 Gran aDgl German b.c. KOH 5.0 800 870 0.352 53.2 22.1 30 2950-18-4 Gran.agDI German b.c. KOH 5.0 800 870 0.366 48.3 22.0 2891-80-2 Pellet Australlan b.c. KOH 10.0 600 870 0.381 31.4 9.6 24.3 14.9 2891-92-3 Pellot Australian b.c. KOH 10.0 600 870 0.402 28.3 8.3 23.4 12.5 2891-92-1 Pellet Australian b.c. KOH 10.0 600 900 0.372 28.7 7.1 21.7 13.5 2891-73-2 Pellet Australian b.c. KOH 10.0 600 900 Q372 30.7 8.3 21.4 14.3 35 2901-17-2 Pellet Australian b.c. KOH 10.0 700 900 0.356 32.5 9.1 24.0 15.8 2891-52-2 Pellet Australlan b.c. KOH 15.0 700 870 0.367 22.7 6.6 16.0 10.0 2891-50-2 Pellet Australian b.c KOH 15.0 700 870 0.323 25.0 7.2 17.4 11.0 2891-50-3 Pellet Australlan b.c. KOH 15.0 700 900 0.369 20.0 4.4 14.4 7.2 2891-50-4 Pellet Australlan b.c. KOH 15.0 700 900 0.343 22.9 5.9 16.3 8.8 40 2891-60-4 Pellet Australian b.c. KOH 30.0 700 870 0.314 27.4 8.0 2891-62-1 Pellet Australian b.c. KOH 30.0 700 870 0.275 32.9 10.9 289148-1 Pellet Australian b.c. KOH 30.0 700 870 0.261 43.6 13.9 2891-16-1 Pellet Australian b.c. KOH 30.0 700 870 0.216 52.6 20.0 289148-3 Pellet Australlan b.c. KOH 30.0 700 900 0.251 37.4 12.4 ~5 289149-1 Pellet Australlan bc KOH 30.0 700 900 0.209 50.7 18.5 2873-65-1 Gran.aDDI Australian b.c. K2CO3 5.0 700 900 0371 33.1 7.7 2873-76-3 Gran.a9çil Australian b.c. K2CO3 5.0 700 900 0.381 37.8 11.0 2873-65-2 Gran.aoal Australlan b.c. K2CO3 5.0 700 950 0.408 25.8 5.2 2873-67-1 Gran.aDDI Australlan b.c. K2CO3 5.0 700 950 0.383 35.1 9.2 TABLE I (continued) Startino Impre~nant Charrin~ Adivation Apparent Hexan3 Butane Test Form Materlal Typo Level Tomperature Tumperaturs Density Capacity Working Capacity Workino Number (% by wt) (C) (C) (g/oc) (%) Capacity (%) Capacity (%) (%) 2880-34-2 Pellet Australlan b c. NaOH 5.0 700 870 0.294 20.7 7.7 ~ -2880-32-1 Pollct Australian b.c. NaOH 5.0 700 900 0.331 23.1 7.6 2880-32-2 Pellet Australian b.c. NaOH 5.0 700 900 0.327 20.3 8.0 2880-37-2 Pellet Australian b.c. NaOH 5.0 700 950 0.338 17.8 5.0 2880-37-1 Pellot Australian b.c. NaOH 5.0 700 950 0.315 18.8 5.4 10 2880-75-1 Pellet Australlan b.c. KOH/NaOH 2.5/0.5 700 870 0.346 29.9 8,3 28û0-75-2 Pellet Australian b.c. KOH/NaOH 2.5/0.5 700 870 0.342 28.4 8.2 2880-76-1 Pellet Ausualian b.c. KOH/NaOH 2.5/0.5 700 870 0.325 33.1 9.7 2880-74-3 Pellet Australian b c. KOH/NaOH 2.5/0.5 700 900 0.335 30.9 8.2 2880-74-4 Pellet Australlan b.c. KOH/NaOH 2.5/0.5 700 900 0.323 31.0 9.1 1 5 2880-74-1 Pellet Australian b c. KOH/NaOH 2.5/0.5 700 900 0.320 36.0 9.9 2880-7û-2 Pellet Australlan b.c. KOH/NaOH 2.5/0.5 700 900 0.325 34.2 8.8 2880-27-4 Pellet Amerlcan llgnite KOH 2 5 700 900 0.369 16.9 6.7 2880-28-1 Pellet Amerlcan 1i3nite KOH 2.5 700 900 0.355 15.6 6.7 2880-30-2 Pellet American lionite KOH 2.5 700 950 0 355 18.8 6.7 20 2880-30-3 Pellet American li~nite KOH 2.5 700 950 0.350 15.2 6.5 Comparative Carbon Tests Comparative performance studies were conducted using several known products 25and the improved KOH treated product of the present invention. Table ll below sets forth a comparison of two carbons against the carbons of the present invention.
213~3~6 __________________________________________________________ Table II
COMPARATIVE WORKING CAPACITY TESTS
Product (substrate) Gasoline Working Capacity (9/l) Prior Art Sample 1 34.0 g/l (wood pellet) Prior Art Sample 2 29.4 9/1 (lignite) Present invention 49.7 g/l 10Sample 1 (pellet) Present Invention 57.0 9/1 Sample 2 (granular) 15Present Invention 65.0 g/l Sample 3 (granular) __________________________________________________________ Prior art sample 1 (a wood-char-based pelle~
impregnated with KOH, steam activated) has a 34 9/l working capacity. The prior art sample 2 (Karl Higher gasoline working capacities are generally associated with higher hexane working capacities.
Test for determining gasoline working capacity is set forth in SAE Technical Paper Series 890621, 1989.
S~BsTlruTE SH~ET
W094/00382 PCT/US93/ ~ ~
2~3~7~
publication) lignite (brown coal) yields a 29.4 9/1 capacity. The present invention sample 1 activated carbon has a yasoline working capacity of 49.7 9/l. As established above, present invention sample 1 achieves an increase in gasoline working capacity of at least 69% over prior art sample 1 and at least 46% over prior art sample 2. The favorable results achieved with the present invention sample 2 activated carbon are even more remarkable, demonstrating an increase in working capacity of at least 91% over prior art sample 2 and at least 67%
over prior art sample 1.
Due to the increased gasoline working capacities of the carbons of the present invention, less activated carbon filter material is required to achieve the working capacities of less adsorptive carbons. Significant savings can be achieved using smaller canisters filled with activated carbons of the present invention.
Althoush the carbons offered by the preser.t invention have been described in detail in the foregoir.g for purposes of illustration, it is to be understood that such details are solely for that purpose and that variations may be made therein by those skilled in the art without departing from the spirit and scope of the invention as described in the following claims.
SUBSTITUTE SHEET
(6) the amount of moisture present or added at each step;
and (7) the activity of the starting lignite (~rown coal).
Other parameters also affect the final characteristics of the activated carbon of the present invention, but to a lesser extent.
Tests were performed to provide a description of the unique qualities of activated carbons of the present invention. Also, preferred methods of preparing the activated carbons are set forth. It has been found, for example, that Australian lignite (brown coal) produced carbons with good hexane adsorption and working capacities. It has also been found that other lignites SUBSTITUTE SHEET
W094/00382 PCT/US93/ ~
2~38~6 produce exceptionally good working capacities. In these tests, the lignite (brown coal) was treated with a solution of KOH, charred in an inert atmosphere and activated with steam.
Initial preparation comprises pulverizing the dry lignite (brown coal) and then treating it with a solution of KOH and, thereafter, forming it into two-millimeter pellets. This procedure maximizes the advantages of the potential interaction between KOH and oxygenated surface groups of lignite (brown coal) for the present invention. These pellets were charred in an inert atmosphere and activated in steam. This preferred method of treating the lignite with KOH prior to charring yielded surprisingly desirable results.
i5 In preliminary tests, two-millimeter pellets were formed from lignite (brown coal) with a 2.5% KO~
loading. The pellets were air-dried for three days, charred in nitrogen at 700C, and activated in steam at 870-950C. About 20 to 25 mg of activated carbon were pllt in a micro balance and were kept at constant temperature of 30C. A stream of 100 ml/minute of pure nitrogen saturated with n-hexane at 0C was passed through the carbon for 20 minutes. Then a stream of 100 ml/minute of pure nitrogen was passed through the carbon saturated with hexane f~r 20 minutes. The difference in weights of the carbon is defined as the hexane working capacity.
Hexane capacity and working capacity of pellets that were activated in the range of 870-900C reachec approximately 42-45% and 13-14~, respectively. Butane capacity and working capacity reached approximately 36-~6~
and 22-24%, respectively. This butane capacity range is higher than the highest capacity of the known commercial SUBSTITUTE SHEET
2138~
. .
_g_ carbons ( WVA1100~ with 34%). Therefore, the treatment of dry lignite (brown coal) with KOH prior to charring resulted in an activated carbon having a large adsorption capacity and a high working capacity.
Different levels of potassium hydroxide or salt treatment and charring temperatures were studied to produce optimal working capacity. Tests were run on Australian lignite (brown coal) pellets with up to 30% KOH
(by weight). A hexane working capacity of 20% was achieved using this level of KOH impregnation.
These test led to products made with 5% KOH
having a variety of highly desirable characteristics, particularly for use in gas phase applications such as evaporative loss control canisters, solvent recovery, and others. Although lignites (brown coal) impregnated with 2.5% and 1.25% KOH resulted in activated carbons useful for some applications, the 5.0% level of KOH resulted in carbons with higher activity. Carbons at the 2.5% KOH
level show greater butane working capacities than 1.25%
KOH carbons. Potassium hydroxide catalyzed activation of lignite (brown coal), both in granular agglomerated and sized nonagglomerated forms, resulted in activated carbor.s with good hexane capacities and working capacities.
Further samples of the lignite (brown coal) were treated with a solution of KOH, and thereafte.
agglomerated into 6x20 mesh granular form or sized into 8x30 mesh directly then charred in a nitrogen atmosphere at ?o0C for 10 minutes. The char was then activated in steam. Flow diagrams for the preparation of three forms of activated carbon of the present invention are shown in Pigures 1, 2 and 3.
Westvaco Corporation.
SUBSTITUTE S~EET
W094/00382 ~ ~ ~ 837 ~ PCT/US93/ ~ 4 To achieve an enhanced pore structure, KOH
solution was sprayed into the pulverized lignite to a KOH
loading of 5%. The wet mixture of coal and KOH was pelletized without further addition of any binder to form 2mm pellets. The wet pellets were charred in a nitrogen atmosphere at 700C for 10 minutes. It was discovered that by reducing the steam delivery rate and by diluting the activation gas with nitrogen, hexane working capacity was increased dramatically and increased the yield of the carbon. Hexane working capacity was 20.5%.
In further tests, KOH loading of 5.2% in the char feedstock produced the activated product with hexane capacity reaching approximately 45% at activation temperatures of 870-900C. The hexane working capacity of these products reached approximately 13-14%. (The hexane capacity and hexane working capacity are approximately 32%
and 17%, respectively for a first commercially used carbon and 44% and 20%, respectively for a second commercially used carbon).
Further tests were performed using pulverizeà
dry lignite (brown coal) having a water content of 1~.4%
mixed with a solution consisting of 25% (by weight of lignite) water and 5% (by weight of lignite) potassium hydroxide. The mixture was agglomerated, crushed, and screened to 8x30 mesh. This granular material was charred under an inert atmosphere at 800C for 20 minutes. The char was activated in a steam atmosphere at 870C to produce activated carbons of the present invention.
Superior activated carbons were produced by this process;
a first sample activated for 230 minutes had a hexane working capacity of 17.7%, and a second example activated for 250 minutes had a hexane working capacity of 22.1%.
The activated carbon of the preser.. invention using lignites (brown coal) has an apparent density as low SUBST~TUTE SHEET
2138~6 ~ 0 94/00382 PC~r/US93/05804 as 250 9/1 or lower. These surprising low densities are partly responsible for the superior perfarmance. These attributes of surprisingly low apparent density and superior hexane working capacity provide an activated carbon which is remarkably effective as an adsorbent for a large range and number of applications.
Of the various treatment methodologies available, the most reliable method is treatment of the lignite (brown coal) by spraying with a solution of the hydroxide or salt. Methods of preparation may include one, two or more treatment cycles with the selected hydroxide or salt(s) by spraying, wetting or other process, In producing the carbons of the present invention, the constituents should preferably be applied to the lignite (brown coal) using a single application.
The resulting mixture may thereafter be, as desired or necessary, thermally processed by charring and steam activation into the desired activated carbon product. In addition to this single application method, a method involving a second application (by solution or spray operation) can also be used to achieve the desired hydroxide or salt loadings. This two-step application can also be used to achieve uniform high hydroxide or sa t loadings, or application of different liquids than those applied during the first loading.
Pormulations containing various loadings of potassium or sodium hydroxide or salts thereof on granular, pelletized, and other shaped carbonaceous particles of differing mesh sizes will likewise desirably perform. Low-moisture content (e.q., less than 20% by weight) of the lignite (brown coal) prior to charrinq and was discovered to be a factor in enhancing the performance ~t~2ff;~the carbons after activation.
SUB~TIT~TE SHEET
~A21 38376 Numerous examples of lignites (brown coals) were prepared in accordance with the present invention and tested. The results of these tests are described in Table 1.
TABLE I
Startlng ImpreDnan~ Cbarrlng Adivation Apparcnt HeJran~ Butano Test Number Form Materlal Type Levol Temporatur~ remperatur~ Density Capacity Working Capacity Working-(% by V~U (C) (Ci lg/oc) (X) Capacity (X) Capacity 1%) (S6) Z90143-1 Pellot Au~trallanù.c. KOH 5.0 500 900 0.306 37.5 9.0 31.3 17.8 290143-Z Pellet Australian b.c. KOH 5.0 500 900 0.299 39.2 10.9 35.8 21.1 1 0 290143-3 Pellut Australianb.c. KOH 5.0 500 900 0.281 44.6 11 8 31.6 20.4 2901-14-5 Pellet Australian b.c. KOH 5.0 800 870 0.321 33.7 9.9 30.2 18.1 2901-15-1 Pellot Australianb.c. KOH 5.0 600 870 0.313 35.7 11.7 28.1 18.8 2901-17-1 Pellet Australian b.c. KOH 5.0 600 900 0.325 32.7 9.7 25.7 15.6 2901-15-5 Pellet Australlanb.c. KOH 5.0 ûO0 900 0.310 37.5 9.ff 27.2 17.3 1 5 2891-58-2 Pellot Australianbc KOH 50 700 870 0.343 30.0 8.7 28.8 16.1 2891-58-3 Pellot Australianb.c. KOH 5.0 700 870 0.341 35.9 10.1 29.4 17.1 2891-56-4 Pellet Australianb.c. KOH 5.0 700 900 0.326 35.7 10.5 26.0 16.8 2891-57-1 Pollot Australianb.c. KOH 5.0 700 900 0.316 42.0 12.7 29.6 21.1 2891-65-1 Pellet Australianb.c. KOH 5.0 700 950 0.319 39.0 10.8 27.1 17.0 2891-85-4 Pellet Australianb.c. KOH 5.0 700 950 0.293 37.6 10.6 29.2 18.9 2904-48-4 Pellet Australian b.c. KOH 2.5 800 870 0.338 - - 30.5 16.4 2904-48-2 Pellet Australianb.c. KOH 2.5 800 950 0.307 - - 31.1 19.7 2904-50-1 Pellet Australlan b.c. KOH 2.5 700 870 0.304 - - 29.8 16.4 2904-49-5 Pellet Australian b.c. KOH 2,5 700 950 0.281 - - 29.5 19.0 2904-37-3 Pellet Australianb.c. KOH 2.5 700 900 0.329 - - 30.7 18.7 2904-374 Pellet Austraiian b.c. KOH 2.5 700 900 0.310 - - 40.0 22.6 2904-38-1 Pellet Australian b.c. KOH 2.5 700 900 0276 - - 31.4 25.3 2880-20-2 Pellet Australlan b.c. KOH 1.25 700 840 0.344 18.1 6.2 2880-13-2 Pellet Australian b.c. KOH 1.25 700 870 0.333 26.7 9.5 2880-14-2 Pellet Australianb.c. KOH 125 700 900 0.329 22.2 7.0 1880-15-1 Pellet Australianb.c. KOH 1.25 700 900 0.294 293 10.3 * About 20 to 25 mg of activated carbon were put in a micro balance and were kept at constant temperature of 30C. A stream of 100 ml/minute of pure butane was passed through the carbon for 15 minutes. Then a stream of 100 ml/minute of pure nitrogen was passed through the carbon saturated with butane for 20 minutes. The difference in weights of the carbon is defined as the butane working capacity.
r~.2 1 3~376 TABLE I (continued) StartinD Impregnant Charring Adivation Apparent Hexane Butane Test Form Materlal Type Level Temperature Temperature Density Capacity Working Capacity Working Number (% by wU (C) (C) (a/oc) (%) Capacity (%) Capacity (%) (%) 2921-10-3 Pellet German b.c. KOH 5.0 800 820 - 32.6 14.3 25.2 17.3 292149-5 Pellct German b.c. KOH 5.0 800 885 0.337 35.8 12.0 30.7 19.5 292149-1 Pellut German b.c. KOH 5.0 800 885 0.359 38.0 14.6 Z8.0 18.2 292149-7 Pellet German b.c. KOH 5.0 800 950 0.338 32.9 12.2 27.3 17.4 292149-8 Pellet German b.c. KOH 5.0 800 950 0.321 41.8 16.0 27.0 17.4 1 0 2921-11-6 Pellet German b.c. KOH 5.0 800 950 0.296 42.3 16.3 30.5 19.9 2912-12-1 Pellet German b.c. KOH 5.0 800 950 0.299 39.4 14.9 19.3 16.0 2921-12-2 Pellet German b.c. KOH 5.0 800 950 0.303 44.7 16.8 33.9 21.3 2921-13-2 Pellet German b.c. KOH 5.0 800 950 0.299 46.9 18.4 349 21.6 2921-13-1 Pellet German b.c. KOH 5.0 800 950 0.280 46.4 18.7 33.1 20 9 1 5 2921-29-7 Pellet Gorman b.c. KOH 5.0 800 950 0.273 45.8 20.5 30.4 20.0 2921-33-2 Pellet German b.c. KOH 5.0 800 950 0.293 42.6 19.9 29.9 19.5 2921-33-3 Gran.UnaEigl German b.c. KOH 5.0 800 950 0.240 53.8 22.7 39.4 26.3 2921-33-4 Gran.Unaagl Genman b.c. KOH 5.0 800 950 0.252 52.2 22.2 36.4 24.0 2921-33-5 Gran.Unagçil German b.c. KOH 5.0 800 950 0.247 55.9 22.8 37.3 24.7 20 2921-37-1 Gran.Unaggl German b.c. KOH 5.0 800 950 0.246 51.6 20.7 36.9 24.3 2921-76-8 Gran.aDsl Gorman b.c. KOH 2.5 800 950 0.278 46.9 17.6 39.3 26.5 2921-76-4 Gran.aDDI German b.c. KOH 2.5 800 950 0.269 52.4 22.1 38.1 28.0 2921-76-7 Gran~aDDl German b.c. KOH 2.5 800 950 0.309 44,5 15.6 34.7 23.6 2921-82-1 Gran.aDDI German b.c. KOH 5.0 800 950 0.303 56.5 25.4 39.3 26.3 2 5 2921-82-2 Gran.aggl German b.c. KOH 5.0 800 950 0306 53.9 22.2 34.3 23.4 2921-82-3 Gran~aDDI German b.c. KOH 5.0 800 950 0.315 52.4 21.5 37.1 21.9 2950-14-1 Gran.aDDI German b.c. KOH 5.0 800 870 0.357 53.1 21.3 2950-14-2 Gran.agDI German b.c. KOH 5.0 800 870 0.338 54 6 22.2 2950-14-3 Gran aDgl German b.c. KOH 5.0 800 870 0.352 53.2 22.1 30 2950-18-4 Gran.agDI German b.c. KOH 5.0 800 870 0.366 48.3 22.0 2891-80-2 Pellet Australlan b.c. KOH 10.0 600 870 0.381 31.4 9.6 24.3 14.9 2891-92-3 Pellot Australian b.c. KOH 10.0 600 870 0.402 28.3 8.3 23.4 12.5 2891-92-1 Pellet Australian b.c. KOH 10.0 600 900 0.372 28.7 7.1 21.7 13.5 2891-73-2 Pellet Australian b.c. KOH 10.0 600 900 Q372 30.7 8.3 21.4 14.3 35 2901-17-2 Pellet Australian b.c. KOH 10.0 700 900 0.356 32.5 9.1 24.0 15.8 2891-52-2 Pellet Australlan b.c. KOH 15.0 700 870 0.367 22.7 6.6 16.0 10.0 2891-50-2 Pellet Australian b.c KOH 15.0 700 870 0.323 25.0 7.2 17.4 11.0 2891-50-3 Pellet Australlan b.c. KOH 15.0 700 900 0.369 20.0 4.4 14.4 7.2 2891-50-4 Pellet Australlan b.c. KOH 15.0 700 900 0.343 22.9 5.9 16.3 8.8 40 2891-60-4 Pellet Australian b.c. KOH 30.0 700 870 0.314 27.4 8.0 2891-62-1 Pellet Australian b.c. KOH 30.0 700 870 0.275 32.9 10.9 289148-1 Pellet Australian b.c. KOH 30.0 700 870 0.261 43.6 13.9 2891-16-1 Pellet Australian b.c. KOH 30.0 700 870 0.216 52.6 20.0 289148-3 Pellet Australlan b.c. KOH 30.0 700 900 0.251 37.4 12.4 ~5 289149-1 Pellet Australlan bc KOH 30.0 700 900 0.209 50.7 18.5 2873-65-1 Gran.aDDI Australian b.c. K2CO3 5.0 700 900 0371 33.1 7.7 2873-76-3 Gran.a9çil Australian b.c. K2CO3 5.0 700 900 0.381 37.8 11.0 2873-65-2 Gran.aoal Australlan b.c. K2CO3 5.0 700 950 0.408 25.8 5.2 2873-67-1 Gran.aDDI Australlan b.c. K2CO3 5.0 700 950 0.383 35.1 9.2 TABLE I (continued) Startino Impre~nant Charrin~ Adivation Apparent Hexan3 Butane Test Form Materlal Typo Level Tomperature Tumperaturs Density Capacity Working Capacity Workino Number (% by wt) (C) (C) (g/oc) (%) Capacity (%) Capacity (%) (%) 2880-34-2 Pellet Australlan b c. NaOH 5.0 700 870 0.294 20.7 7.7 ~ -2880-32-1 Pollct Australian b.c. NaOH 5.0 700 900 0.331 23.1 7.6 2880-32-2 Pellet Australian b.c. NaOH 5.0 700 900 0.327 20.3 8.0 2880-37-2 Pellet Australian b.c. NaOH 5.0 700 950 0.338 17.8 5.0 2880-37-1 Pellot Australian b.c. NaOH 5.0 700 950 0.315 18.8 5.4 10 2880-75-1 Pellet Australlan b.c. KOH/NaOH 2.5/0.5 700 870 0.346 29.9 8,3 28û0-75-2 Pellet Australian b.c. KOH/NaOH 2.5/0.5 700 870 0.342 28.4 8.2 2880-76-1 Pellet Ausualian b.c. KOH/NaOH 2.5/0.5 700 870 0.325 33.1 9.7 2880-74-3 Pellet Australian b c. KOH/NaOH 2.5/0.5 700 900 0.335 30.9 8.2 2880-74-4 Pellet Australlan b.c. KOH/NaOH 2.5/0.5 700 900 0.323 31.0 9.1 1 5 2880-74-1 Pellet Australian b c. KOH/NaOH 2.5/0.5 700 900 0.320 36.0 9.9 2880-7û-2 Pellet Australlan b.c. KOH/NaOH 2.5/0.5 700 900 0.325 34.2 8.8 2880-27-4 Pellet Amerlcan llgnite KOH 2 5 700 900 0.369 16.9 6.7 2880-28-1 Pellet Amerlcan 1i3nite KOH 2.5 700 900 0.355 15.6 6.7 2880-30-2 Pellet American lionite KOH 2.5 700 950 0 355 18.8 6.7 20 2880-30-3 Pellet American li~nite KOH 2.5 700 950 0.350 15.2 6.5 Comparative Carbon Tests Comparative performance studies were conducted using several known products 25and the improved KOH treated product of the present invention. Table ll below sets forth a comparison of two carbons against the carbons of the present invention.
213~3~6 __________________________________________________________ Table II
COMPARATIVE WORKING CAPACITY TESTS
Product (substrate) Gasoline Working Capacity (9/l) Prior Art Sample 1 34.0 g/l (wood pellet) Prior Art Sample 2 29.4 9/1 (lignite) Present invention 49.7 g/l 10Sample 1 (pellet) Present Invention 57.0 9/1 Sample 2 (granular) 15Present Invention 65.0 g/l Sample 3 (granular) __________________________________________________________ Prior art sample 1 (a wood-char-based pelle~
impregnated with KOH, steam activated) has a 34 9/l working capacity. The prior art sample 2 (Karl Higher gasoline working capacities are generally associated with higher hexane working capacities.
Test for determining gasoline working capacity is set forth in SAE Technical Paper Series 890621, 1989.
S~BsTlruTE SH~ET
W094/00382 PCT/US93/ ~ ~
2~3~7~
publication) lignite (brown coal) yields a 29.4 9/1 capacity. The present invention sample 1 activated carbon has a yasoline working capacity of 49.7 9/l. As established above, present invention sample 1 achieves an increase in gasoline working capacity of at least 69% over prior art sample 1 and at least 46% over prior art sample 2. The favorable results achieved with the present invention sample 2 activated carbon are even more remarkable, demonstrating an increase in working capacity of at least 91% over prior art sample 2 and at least 67%
over prior art sample 1.
Due to the increased gasoline working capacities of the carbons of the present invention, less activated carbon filter material is required to achieve the working capacities of less adsorptive carbons. Significant savings can be achieved using smaller canisters filled with activated carbons of the present invention.
Althoush the carbons offered by the preser.t invention have been described in detail in the foregoir.g for purposes of illustration, it is to be understood that such details are solely for that purpose and that variations may be made therein by those skilled in the art without departing from the spirit and scope of the invention as described in the following claims.
SUBSTITUTE SHEET
Claims (35)
1. An activated carbon comprising a dry lignite or brown coal treated to result in a composition comprising up to about 30%, by weight, of one or more compounds selected from the group of potassium hydroxide and salts thereof and sodium hydroxide and salts thereof, then charred and thereafter activated.
2. An activated carbon as set forth in Claim 1 wherein at least one of said compounds is present in an amount of at least 1.25% by weight.
3. An activated carbon as set forth in Claim 1 or 2, wherein said potassium compounds include potassium hydroxide and said sodium compounds include sodium hydroxide.
4. An activated carbon as set forth in Claim 1, wherein said lignite or brown coal is dried to a moisture content of less than 20% by weight prior to treatment with said compound.
5. A lignite or brown coal based activated carbon having up to about 40%, by weight, of at least one compound residue selected from the group of potassium hydroxide and salts thereof and sodium hydroxide and salts thereof, wherein said activated carbon has an apparent density of less than about 370 g/l, and a hexane working capacity of at least 5.4%.
6. An activated carbon as set forth in Claim 1 or 2, wherein said activated carbon has an apparent density of between about 230 and 370 g/l.
7. An activated carbon as set forth in Claim 1 or 2, wherein said activated carbon has a hexane working capacity of at least 5.4%.
8. An activated carbon as set forth in Claim 6, wherein said potassium compound is potassium hydroxide and said sodium compound is sodium hydroxide.
9. An activated carbon as set forth in Claim 6, wherein said activated carbon has about a 10%
residue of a potassium salt.
residue of a potassium salt.
10. An activated carbon as set forth in Claim 5 wherein said lignite or brown coal has an initial moisture content of less than 20%, is charred at a temperature between 500 and 900°C, and activated by steam at a temperature between 800 and 950°C.
11. A method for preparing an activated carbon comprising the steps:
A. treating a lignite or brown coal having a moisture content of less than 20% at least once with at least one compound selected from the group of potassium hydroxide and salts thereof and sodium hydroxide and salts thereof;
B. charring said impregnated lignite or brown coal; and C. activating said charred lignite or brown coal.
A. treating a lignite or brown coal having a moisture content of less than 20% at least once with at least one compound selected from the group of potassium hydroxide and salts thereof and sodium hydroxide and salts thereof;
B. charring said impregnated lignite or brown coal; and C. activating said charred lignite or brown coal.
12. A method of preparation of an activated carbon as set forth in Claim 11, wherein said potassium compound is in the form of potassium hydroxide and said sodium compound is in the form of sodium hydroxide.
13. A method of preparation of an activated carbon as set forth in Claim 11, wherein the lignite is charred at temperatures of about 600 to 800° C.
14. A method of preparation of an activated carbon as set forth in Claim 11, wherein the charred lignite is activated with steam at temperatures of about 800 to 950°C.
15. A method of preparation of an activated carbon as set forth in Claim 11, additionally comprising the steps:
D. cooling the activated carbon after activation; and E. washing the activated carbon at least once after cooling and drying said washed activated carbon.
D. cooling the activated carbon after activation; and E. washing the activated carbon at least once after cooling and drying said washed activated carbon.
16. A process for adsorbing organic gases, vapors and liquids utilizing an activated carbon, said activated carbon prepared from a dry lignite or brown coal and having a residue up to about 40%, by weight, of one or more compounds selected from the group of potassium salts and sodium salts, said activated carbon having an apparent density of less than 370 g/l and a hexane working capacity of at least 5.4%.
17. A process as set forth in Claim 16 wherein said organic gases and vapors include hydrocarbons, associated with automotive evaporative emission control devices, protective filters, solvent recovery systems and other industrial applications.
18. A method of adsorbing organic gases, vapors and liquids with an activated carbon useful in automotive evaporative emission control devices, protective filters, solvent recovery systems and industrial applications, said activated carbon having up to about 40%, by weight, of a residue selected from the group of potassium salts and sodium salts, wherein said activated carbon has an apparent density of less than about 370 g/l and a hexane working capacity of at least 5.4%.
19. A method as set forth in Claim 18, wherein the organic gases, vapors and liquids to be adsorbed are hydrocarbons.
20. A method as set forth in Claim 18, wherein said adsorbent has an apparent density of between 230 and 370 g/l.
21. A method as set forth in Claim 18, wherein said activated carbon has about a 10% residue of the potassium or sodium salt.
22. A method as set forth in Claim 18, wherein said activated carbon is produced from a lignite or brown coal having an initial moisture content, by weight, of less than 20%.
23. A method as set forth in Claim 18, wherein said activated carbon is produced from a lignite charred at temperatures of about 600 to 800° C.
24. A method as set forth in Claim 18, wherein said activated carbon is produced from a charred lignite activated with steam at temperatures of about 800 to 950°C.
25. An activated carbon comprising a dry lignite or brown coal treated with a composition comprising from about 1.25% to 30%, by weight, of said dry lignites or brown coal of one or more compounds selected from the group of potassium hydroxide, and potassium salts, sodium hydroxide and sodium salts, then charred and thereafter activated.
26. An activated carbon as set forth in Claim 25, wherein said potassium compounds include potassium hydroxide and said sodium compounds include sodium hydroxide.
27. An activated carbon as set forth in Claim 1, wherein said lignite or brown coal is dried to a moisture content of less than 20% by weight prior to treatment with said compounds.
28. A lignite or brown coal based activated carbon having from about 1.25% to 40%, by weight of said dry lignites or brown coal, of at least one compound residue selected from the group of potassium hydroxide, potassium salts, sodium hydroxide and sodium salts thereof, wherein said activated carbon has an apparent density of less than about 370 g/l, and a hexane working capacity of at least 5.4%.
29. An activated carbon as set forth in Claim 25, wherein said activated carbon has an apparent density of between about 230 and 370 g/l.
30. An activated carbon as set forth in Claim 25, wherein said activated carbon has a hexane working capacity of at least 5.4%.
31. A method for preparing an activated carbon comprising the steps:
A. treating a lignite or brown coal having a moisture content of less than 20% at least once with at least one compound selected from the group of potassium hydroxide, potassium salts, sodium hydroxide and sodium salts;
B. charring said impregnated lignite or brown coal; and C. activating said charred lignite or brown coal.
A. treating a lignite or brown coal having a moisture content of less than 20% at least once with at least one compound selected from the group of potassium hydroxide, potassium salts, sodium hydroxide and sodium salts;
B. charring said impregnated lignite or brown coal; and C. activating said charred lignite or brown coal.
32. A method of preparation of an activated carbon as set forth in Claim 11, wherein said potassium compound is in the form of potassium hydroxide and said sodium compound is in the form of sodium hydroxide.
33. A method of preparation of an activated carbon as set forth in Claim 11, wherein the lignite is charred at temperatures of about 600 to 800° C.
34. A method of preparation of an activated carbon as set forth in Claim 11, wherein the charred lignite is activated with steam at temperatures of about 800 to 950° C.
35. A method of preparation of an activated carbon as set forth in Claim 11, additionally comprising the steps:
D. cooling the activated carbon after activation;
and E. washing the activated carbon at least once after cooling and drying said washed activated carbon.
D. cooling the activated carbon after activation;
and E. washing the activated carbon at least once after cooling and drying said washed activated carbon.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US90135892A | 1992-06-19 | 1992-06-19 | |
| US901,358 | 1992-06-19 | ||
| PCT/US1993/005804 WO1994000382A1 (en) | 1992-06-19 | 1993-06-17 | Activated carbon by treatment of lignites with potassium and/or sodium hydroxide or salts and adsorption therewith |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2138376A1 true CA2138376A1 (en) | 1994-01-06 |
Family
ID=25414013
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002138376A Abandoned CA2138376A1 (en) | 1992-06-19 | 1993-06-17 | Activated carbon by treatment of lignites with potassium and/or sodium hydroxide or salts and adsorption therewith |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH07508215A (en) |
| CA (1) | CA2138376A1 (en) |
| WO (1) | WO1994000382A1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2176120B1 (en) * | 2001-04-17 | 2004-03-16 | Universidasd De Alicante | PROCEDURE FOR OBTAINING ACTIVATED CARBONS BY CHEMICAL ACTIVATION WITH SODIUM HYDROXIDE, POTASSIC HYDROXIDE OR ITS MIXTURES. |
| ES2176121B2 (en) * | 2001-04-17 | 2004-08-01 | Universidad De Alicante | PROCEDURE FOR OBTAINING ACTIVATED CARBONS BY PHYSICAL MIXTURE OF CARBON PRECURSORS WITH SODIUM HYDROXIDE OR MIXTURES SODIUM HYDROXIDE / POTASSIC HYDROXIDE. |
| GB0918069D0 (en) | 2009-10-15 | 2009-12-02 | Ineos Fluor Holdings Ltd | Process |
| RU2449948C1 (en) * | 2010-10-29 | 2012-05-10 | Российская Федерация, от имени которой выступает Министерство промышленности и торговли Российской Федерации (Минпромторг России) | Method of producing active coal |
| US9023755B2 (en) * | 2012-12-18 | 2015-05-05 | Cabot Corporation | Siloxane removal from gases using lignite-enhanced activated carbons and adsorbent media used therefor |
| CN105664892A (en) * | 2016-01-20 | 2016-06-15 | 昆明理工大学 | Method for preparing arsenic adsorbing material by lignite and yellow phosphorus water-quenched slag |
| WO2021119671A1 (en) * | 2019-12-09 | 2021-06-17 | Carbonxt, Inc. | Water-resistant and high strength carbon products |
| CN113233462A (en) * | 2021-03-15 | 2021-08-10 | 河南省冶金研究所有限责任公司 | Preparation method of lignite-based activated carbon with high specific surface area |
| CN113880083B (en) * | 2021-10-27 | 2023-06-16 | 中冶集团武汉勘察研究院有限公司 | Method for preparing biomass activated carbon by using loofah sponge |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4945681B1 (en) * | 1965-10-13 | 1974-12-05 | ||
| DE1669318A1 (en) * | 1967-01-13 | 1972-05-04 | Takeda Chemical Industries Ltd | Process for removing sulfur dioxide from gases containing sulfur dioxide and means therefor |
| US3764561A (en) * | 1971-03-09 | 1973-10-09 | Takeda Chemical Industries Ltd | Activated carbon from admixture of coking coal and inorganic potassium salts |
| DE2230527A1 (en) * | 1972-06-22 | 1974-01-10 | Bosch Gmbh Robert | FAN WITH AN ELECTRIC MOTOR AND A FAN WHEEL DRIVEN BY THIS |
| NZ180336A (en) * | 1975-03-18 | 1978-07-28 | Commw Scient Ind Res Org | Producing active carbon from brown coal |
| DD227946B5 (en) * | 1984-07-03 | 1994-03-31 | Univ Freiberg Tech Bergakad | PROCESS FOR PREPARING ABRASIVE, CORNECTIVE CARBON |
| GB8523511D0 (en) * | 1985-09-24 | 1985-10-30 | British Petroleum Co Plc | Production of adsorbent carbon |
-
1993
- 1993-06-17 CA CA002138376A patent/CA2138376A1/en not_active Abandoned
- 1993-06-17 JP JP6502455A patent/JPH07508215A/en active Pending
- 1993-06-17 WO PCT/US1993/005804 patent/WO1994000382A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| WO1994000382A1 (en) | 1994-01-06 |
| JPH07508215A (en) | 1995-09-14 |
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