Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B30/00—Compositions for artificial stone, not containing binders
  • C04B30/02—Compositions for artificial stone, not containing binders containing fibrous materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
  • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
  • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
• • 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
  • C01B32/354—After-treatment
  • C01B32/382—Making shaped products, e.g. fibres, spheres, membranes or foam
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/0022—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors

Definitions

• This invention relates to high adsorption capacity activated carbon composites which are made by impregnating support material with a crosslinkable resin, followed by curing the resin, shaping, carbonizing, and activating. These composites have high adsorption capacity per unit volume and are strong and are not subject to attrition as are conventional granulated carbon beds.
• Beds packed with granulated activated carbons have traditionally been used in many liquid and gas purification applications.
• One example of use of a packed granulated activated carbon beds is in the automotive industry in which the bed is mounted on top of the gasoline tank to trap gasoline vapors.
• Another automotive application is in vehicles which use adsorbed natural gas as fuel. The natural gas is adsorbed on activated carbon and is released and combusted to power the vehicle when needed.
• the present invention provides such a carbon body and a method of making it.
• a method for making an activated carbon composite which involves providing a crosslinkable resin and a support material which is wettable by the resin.
• the support material can be cotton, chopped wood, sisal, non- fugitive material, and combinations of these.
• the support is contacted with the resin; and the resin and support material are dried.
• the resin and support material are then shaped, the resin is cured, and the resin and any carbonizable material are carbonized.
• the carbon is then activated to produce the product composite.
• an activated carbon composite produced by the above described method in which the carbon is in the form of a continuous structure reinforced by and uniformly distributed throughout non-fugitive support material .
• the present invention relates to an activated carbon composite.
• the composite can be in the form of a unitary body, or granules.
• a unitary body is characterized preferably by flow through channels which are straight or curved essentially parallel channels for optimum flowability of a fluid work stream therethrough.
• Honeycomb shapes are especially preferred because they offer large flow through area.
• the carbon atoms within the composite are arranged in a continuous uninterrupted structure of random three dimensional graphitic platelets.
• the platelets have angstrom sized pores typically about 5 to about 50 angstroms for adsorption as distinguished from micron-size pores. Pores in several hundred micron size range can be present in the body, but they do not contribute to adsorption capacity.
• the continuous carbon structure can be distinguished from "discontinuous" discrete carbon particles which must be bound to each other and to a substrate with a binder. In such cases, the binder particles are interspersed throughout the carbon particles thus rendering the carbon discontinuous.
• the carbon is supported on and is uniformly distributed throughout a non-fugitive support material which serves to reinforce the body.
• the weight ratio of carbon to non-fugitive support material ranges from about 19:1 to about 1:19, preferably greater than about 1, with about 3:1 to about 9:1 being especially preferred for a good combination of reinforcement and adsorption capacity.
• the bodies are continuous, hard, and strong carbon bodies of high durability. Since there are no discrete discontinuous carbon particles, the problems of attrition associated with conventional granulated beds are eliminated and pressure drop through the body is minimized in the application. Also, since the bodies of the present invention do not have binders and therefore, the adsorption capacity per unit volume is very high.
• the bodies of the present invention are suited for use in any of a wide variety of applications for which activated carbon bodies have been used in the past.
• applications include residential water purification, volatile organic compound emission control, natural gas fuel storage for gas-powered vehicles or equipment, indoor air purification, industrial respirators, automotive cabin air filters, ventless hoods, chemical separations, NO x and SO x control, and exhaust traps for automotive cold start applications.
• Other potential applications include use as ozone filters, mercury collection from municipal incinerators, radon adsorption, automotive gas tank or intake manifold emissions, sewer pump vents, oil-air separations, or any other application wherein adsorption of a component or components from a fluid stream containing multiple components is desired.
• the method for making the bodies involves contacting support material with a crosslinkable resin to wet, in other words, to impregnate or saturate the material with the resin.
• the resin-saturated support material is then dried and shaped, and the resin is then cured and carbonized. The carbon is then activated.
• the resin A critical characteristic of the resin is that it be crosslinkable. These resins form three-dimensional network structures extending throughout the final body. The final body is stable to heat and cannot be made to melt or flow.
• thermosetting resins such as phenolics, furan, epoxies, and thermoplastic polymers such as polyacrylonitrile, polyvinyl chloride, etc., which although not thermosetting, can be crosslinked by high temperature oxidation. It is desirable that the resin give a high carbon yield on carbonization, that is, for example at least about 25%, and preferably at least about 40% based on the amount of cured resin. Thermosetting resins normally give these high yields. Thermosetting resins are the preferred resins. Examples of thermosetting resins that can be used in the practice of the present invention are phenolics, furan, epoxies, and combinations of these.
• Preferred resins are phenolics, furan, and combinations of these because of their high carbon yield and low viscosities at room temperature. Normally, the viscosities can vary from about 50 cps to about 1000 cps . The preferred viscosities are about 100 to about 500 cps.
• the resins can be provided as solids, liquids, solutions, or suspensions.
• One resin that is especially suited to the practice of the present invention is phenolic resole.
• the phenolic resoles are solutions of phenolics in water. A higher viscosity suspension of solid phenolic powder in liquid resin can be used to increase the amount of resin in the support material and thus the final carbon yield.
• One especially suited resin is a phenolic resole resin available from Occidental Chemical Corporation, Niagara Falls, N.Y. under the product name of Plyophen 43290. According to OxyChem® Material Safety Data Sheet No.
• Plyophen 43290 is a liquid one step phenolic resin containing phenol, formaldehyde, and water, having a specific gravity of 1.22-1.24, a boiling point >100°C and a pH of 7.5-7.7 @ 100 gm/1.
• Furan resins are available as liquids.
• One furan that is suitable to the practice of the present invention is supplied by QO Chemicals, Inc. under the name of Furcarb® LP.
• Furcarb® LP resins preparations of phenol (4% max) in furfuryl alcohol and have a specific gravity of 1.2, and a boiling point of 170°C.
• the viscosity is 300 cps .
• the support material must be capable of being wetted and thoroughly impregnated by a solution or suspension of the chosen resin in order to result in the highs amount of carbon in the body for high adsorption capacity described previously.
• the support material is best provided in the form of loose material such as powders or fibers, with fibers being the preferred form for facility in shaping.
• the support material can be made, eg. woven into preshapes of high void volume.
• the support material is therefore distinguishable from continuous or dense inorganic bodies such as cordierite substrates on which only a limited amount of carbon can be coated or supported even if they such bodies porous.
• the weight ratio of carbon to substrate in such bodies is not greater than about 1.
• Some materials that can be used as support materials according to the practice of the present invention are cotton, chopped wood, eg., sawdust or wood fibers, sisal fibers, all of which are fugitive, or non-fugitive materials or combinations of these.
• non-fugitive is meant that the material is non- reactive, non-volatile, and remains essentially unchanged throughout the steps of the process and intact as part of the final product body and form a repeated structure therein, as opposed to burnout materials or carbonized.
• Some non-fugitive materials are cordierite powder, clays, glass powders, alumino-silicate, sand, and combinations of these. Preferred are non-fugitive materials because they contribute to the strength of the final body.
• Some preferred non-fugitive materials are cordierite, clays, glass powders, alumino-silicate and combinations of these. Especially preferred is alumino-silicate.
• fugitive materials aid in formation of the body and serve to support the body and maintain its shape before the curing step. They carbonize during the carbonization step.
• Some fugitive materials, especially cotton fibers are capable of holding a great amount of resin and hence give a high carbon yield in the body, although the strength of such bodies is not as high as bodies with non-fugitive supports.
• Some supporting materials that are especially useful in this form are alumino-silicate, cordierite, cotton, and combinations of these.
• the loose material can be preshaped. It is especially preferred that fibers be in the form of a mat for especially good facility in shaping and to provide a closely knit or strong support for the resin and subsequently the carbon.
• the mat is made preferably from short fibers but in some cases continuous fibers can be used to attain a given configuration in the final composite. Also, for forming mats it is preferred that the fibers be about 1 to 50 and more preferably about 2 to about 10 microns in diameter.
• the mats are of low bulk density (high void volume) .
• the void volume can vary from about 50% to about 98%. Preferred void volumes are about 75% to about 95%.
• the mat be capable of absorbing at least about three times their own weight, and more preferably at least about five times their own weight in resin when impregnated therewith.
• Alumino-silicate fibers, cotton fibers and combinations of these are especially useful in the form of mats.
• One preferred mat is of alumino-silicate fibers, especially in the form of short fibers, such as Fiberfax 970 fiber mat supplied by Carborundum Co., Niagara Falls, N.Y.
• the support material is contacted with the resin to impregnate or saturate the support material thoroughly therewith.
• the resin must be in form of a solution, liquid, or suspension. If the resin is in solid, eg., powder form, it is introduced into a suitable medium, such as liquid phenolic resin solution or water.
• Wetting agents can be used if necessary to enhance the wettability of the support material.
• silane coupling agents can be represented by the formula YRSiX 3 , where X represents a hydrolyzable group typically alkoxy and Y a functional organic group such as amino metheneyloxy, epoxy, etc.
• the R component is typically a small aliphatic linkage.
• silane coupling agent is Z-6020 silane from Dow Corning. It is designated N- (B-aminoethyl) - ⁇ -aminopropyl trimethoxy- silane. Titanate coupling agents can also be used.
• the impregnation can be done by techniques such as dipping or spraying into or spraying with the resin solution or suspension for a mat; or by mixing with support material (loose powder or fibers) in an appropriate mixer and then pouring the mixture into an appropriate mold.
• the support material can be first impregnated with a catalyst which is known to accelerate the curing reaction, and then mixed with the resin. On pouring into the mold, the resin becomes rigid and curing is accomplished.
• catalysts such as ZnCl 2 , PTSA (para- toluene sulfonic acid) , citric acid, or some other catalyst .
• the resin impregnated fibers are then dried to remove the liquid phases, eg., solvents, etc., therefrom.
• the drying advances the resin to a non-tacky but still flexible state, commonly called the "B stage".
• B stage a non-tacky but still flexible state
• partial crosslinking in the resin takes place.
• the drying conditions of temperature and time are chosen depending on the combination and amounts of resin and support material although typical drying temperatures are in the range of about 80°C-110°C. The drying conditions can be adjusted as necessary to achieve the "B" stage.
• the solvent is removed by drying at about 80 r O-85T, and then at about 100°C-110°C for a total time of up to about 3 hours.
• the drying time is about 1.5-2 hours at about 80°C-85 U C and then about 20-30 minutes at about 100°C-110°C to obtain the flexible non-tacky state.
• phenolic resole resin is contacted with support material which is in the form of a mat.
• the mat is preferably either alumino-silicate fibers or cotton fibers, and most preferably alumino-silicate fibers.
• the resin-impregnated support material is then shaped into the desired shape.
• One advantage of the flexible mats is that they are easily handled and can be formed into various shapes by several suitable techniques. This allows great adaptability in applications in which available space is limited such as in automotive and face mask applications.
• One shape that is suitable for automotive applications, for example, is a honeycomb.
• the fibers are in the form of a mat which is impregnated with resin by dipping into the resin and then removing the excess resin.
• Especially suited mats are short fiber aluminosilicate mats and low density cotton fiber mats.
• Especially suited resin for use with these mats is phenolic resole resin.
• the impregnated mats can be stamped into various forms. For example alternated grooves can be created on the mat such as by pressing a wooden cylindrical rod in the soft mat. This grooved mat can be used as is or further shaped into a honeycomb body. This is done by placing strands of the grooved mat on another piece of flat mat and rolling into a cylindrical body.
• the mats can be made into honeycomb bodies by first shaping the mats into a sine wave pattern and then alternately stacking flat and sine wave mats.
• the mats can be corrugated by pressing the mat between a flat surface and wooden sticks.
• the corrugated mat is then rolled into a cylindrical body.
• the resin is then cured in the shaped form by heating under the specific temperature and time conditions required for the specific resin. This can be found in the manufacturer's literature. For example, for phenolic resole 43290 from Occidental Chemical Co. the body is heated to about 140-155°C. The final temperature is attained slowly so that the body does not distort.
• the body is first heated to about 90°C-100°C, then to about 120°C-130°C and held at this temperature for about 1-2 hours. It is then heated to about 140°C-155°C and held for about 30 minutes-2 hours for final cure.
• the curing is done typically in air, although it can also be done in a nitrogen atmosphere.
• the resulting cured resin shaped body is then carbonized and activated to convert the resin to activated carbon.
• the carbonization is carried out by heating the body in an inert or reducing atmosphere such as nitrogen or argon, more typically nitrogen, at about 600°C-1000°C, more typically at about 700°C-1000°C for a length of time of usually about 1-20 hours.
• an inert or reducing atmosphere such as nitrogen or argon, more typically nitrogen, at about 600°C-1000°C, more typically at about 700°C-1000°C for a length of time of usually about 1-20 hours.
• nitrogen or argon more typically nitrogen
• carbonization is done by heating at a rate of about 150°C/hr in N .
• the temperature is held at about 900°C for about 6-10 hours to complete the carbonization.
• the temperature is then reduced to 25°C at a cooling rate of about 150°C/hr.
• the body contains random three dimensional oriented graphitic platelets with amorphous carbon between the platelets. If desired, carbonized mats can be broken into granules at this point.
• the carbon in the body is then activated by partially oxidizing in a suitable oxidant such as C0 2 , steam, air, or a combination of these, etc.
• a suitable oxidant such as C0 2 , steam, air, or a combination of these, etc.
• Activation can be carried out at temperatures between about 700°C-1000°C .
• Activation conditions depend on type and amount of resin, flow rate of gas, etc. For example for phenolic resole and Furcab resins activation conditions are at about 900°C for about 1 hour in C0 2 at a flow rate of about 14.2 1/hr. (about 0.5 CFH (cubic feet per hour) ) .
• the partial oxidation during activation causes the removal of the amorphous carbon and the formation of molecular size porosity between the graphitic platelets.
• Mats can be broken up in granules of various sizes suitable to the application. Breaking up of the mats is done at any point in the process after curing. For example, it can be done either after curing and before carbonizing, or after carbonizing and before activating, or after activating. The granules are then subjected to the remainder of steps thru activation to form the final activated carbon composite.
• Granules made according to the present invention have at least about twice the butane adsorption capacity as commercial activated carbon granules as will be seen in the examples that follow.
• An alumino-silicate short fiber in the form of a low density fiber mat (Fiberfax 970 fiber mat from Carborundum
• the flexible mat was then heated slowly to about 100°C, held at temperature for about 1 hour and then heated to about 125°C and held for about 1 hr. before being finally heated to about 150°C for about 30 minutes to complete cure.
• the procedure resulted in a mat with all the sharp surface features intact with no sign of flow.
• the weight ratio of resin to the fiber after cure was about 8:1.
• the flexible mat was heated at about 100°C for about 1 hour and cured at about 125°C for about 1 hour, and about 150°C for about 1 hr.
• the ratio of the weights of cured resin to that of the fiber mat was about 14:1.
• the resin pick up by the fiber mat was thus almost twice as much as the alumino-silicate fiber mat.
• the flexible mat of example 1 was shaped into a sine- wave type of body.
• a honeycomb shape was generated by alternately stacking flat and sine-wave pieces and cured to obtain a strong honeycomb shape. This shape was then carbonized by being heated to about 900°C at a heating rate of about 150°C/hr in nitrogen (about 6 hours) in nitrogen. The carbonized preform then was activated by carbon dioxide at about 900°C for about 1 hour.
• Example 4b comparative
• a replica of the sample in example 4a was made using corrugated cardboard as a substrate.
• the cardboard was dipped in resin and a honeycomb was fabricated by alternately stacking layers to produce a honeycomb body.
• the cardboard body (or paper body) was carbonized and activated in the same way as the fiber mat body.
• the butane adsorption capacity was measured on the honeycomb bodies of about 2.54 cm ( 1") height and about 2.54 cm (1") diameter by the test described earlier.
• the butane adsorption capacity of the cardboard paper honeycomb body was about 180 mg and that of the fiber mat body was about 560 mg.
• the example clearly shows that resin impregnated bodies made from the paper have very low adsorption capacities due to low resin pick-up.
• the inventive body has three times higher adsorption capacity than that of the paper body.
• the adsorption capacity of the inventive body is twice that of commercial automotive canister granulated bed No. 1 and about 60% higher than commercial automotive canister granulated bed No. 2.
• Example 5 (inventive)
• the flexible fiber mat of example 1 was corrugated by processing between a flat surface and wooden sticks.
• the corrugated mat was rolled into a cylinder, cured, carbonized and activated as in Example 4a.
• This cylindrical shape had a butane adsorption capacity of about 650 mg.
• This inventive body thus has adsorption capacity about 2.67 times commercial bed No. 1 and about 1.8 times bed No. 2.
• Example 6 (inventive)
• the flexible fiber mat of example 1 was cut into about 1 mm x 1 mm cross section strands.
• the strands were placed on another piece of the mat at about 5 mm intervals and the mat was rolled into a cylindrical body.
• This body was cured, carbonized and activated 4a.
• a 2.54 cm (1") diameter by 2.54 cm (1") long cylinder core drilled out of this body had a butane adsorption capacity of about 750 mg.
• the measured capacity is more than twice that of bed No. 2 which was about 358 mg.
• Example 7 (inventive)
• the mat of example 1 was carbonized at about 900°C and activated in C0 2 for about 2 hr . The mat was then crushed into granules measuring about 1-2 millimeter in diameter. The adsorption capacity of the granules was measured by the same method used on the previously described commercial granules. It was found that the butane adsorption capacity was about 160 mg/g of activated carbon in the granules. This adsorption capacity is significantly higher than the adsorption capacity obtained with commercial carbons given in Table 1.

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• 1996
  • 1996-10-11 KR KR1019990703076A patent/KR20000049014A/ko not_active Application Discontinuation
  • 1996-10-11 JP JP51830098A patent/JP2001504793A/ja active Pending
  • 1996-10-11 WO PCT/US1996/016889 patent/WO1998016377A1/en not_active Application Discontinuation
  • 1996-10-11 AU AU74646/96A patent/AU7464696A/en not_active Abandoned
  • 1996-10-11 EP EP96936814A patent/EP0930966A1/de not_active Withdrawn

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