MXPA00007805A - Method of making mesoporous carbon - Google Patents

Abstract

Mesoporous carbon and method of making involves forming a mixture of a high carbon-yielding carbon precursor that when carbonized yields greater than about 40%carbon on a cured basis, and an additive that can be catalyst metal and/or low carbon-yielding carbon precursor that when carbonized yields no greater than about 40%by weight carbon on a cured basis. When a catalyst metal is used, the amount of catalyst metal after the subsequent carbonization step is no greater than about 1 wt.%based on the carbon. The mixture is cured, and the carbon precursors are carbonized and activated to produce mesoporous activated carbon.

Description

METHOD FOR MAKING MESOPOROUS CARBON DESCRIPTIVE MEMORY This application claims the benefit of the provisional applications of USA numbers 60 / 074,241, filed on February 10, 1998, entitled "Mesoporous Carbon Bodies", by Kishor P. Gadkaree, and 60 / 093,396, filed on July 20, 1998, entitled "Method of Making Coal Having Pore Size Distribution in the Mesopore Range", by Gadkaree et al. This invention relates to a method for manufacturing coal of various pore sizes, typically larger than 30 angstroms, from coal precursors, using low yield carbon precursors and / or suitable metal catalyst compounds. This ability to tailor the pore size distribution is especially important for purification as well as catalytic applications.

BACKGROUND OF THE INVENTION Activated carbon has found use in several applications such as air and water purification, hydrocarbon absorption in automotive vapor emission control and cold start hydrocarbon absorption, etc. Although microporous structure carbon (pore diameter of less than 20 angstroms and BET surface area of 1000-3000 m2 / g) is suitable for many applications such as gas phase absorption, for example light hydrocarbons and H2S, some applications require Larger pore sizes in the carbon for absorption and / or optimal catalytic activity. For example, the removal of contaminants of larger particle size such as humins, protein, etc., in liquid phase, in addition to conventional gaseous pollutants, such as hydrocarbons, or certain types of pesticides, require surface properties and pore size distributions. specific. When the catalytic or chemical reaction is limited by mass and heat transfer, the largest pore size in the coal is preferred. In addition, mesoporosity in the coal is sometimes required for adequate catalyst loading and dispersion. Activated carbon monoliths, either in the form of a coating on a substrate, or a structure formed of activated carbon, have found use in several applications especially where durability and low pressure drop is required, such as some chemical reactions that use basic or strongly acidic solvents or other corrosive media. Metal catalysts have been used to manufacture catalysts supported by activated carbon, as described in US 5488023. However, up to now, there has not been a method to manufacture activated carbon having custom properties, porosity, example, for some applications of gas phase and liquid, as well as catalytic.

BRIEF DESCRIPTION OF THE INVENTION According to one aspect of the invention, mesoporous charcoal and a method for making mesoporous char that involves forming a mixture of a high carbon charcoal precursor which when charred yields more than 40% char on a cured base is provided. , and an additive that can be a catalyst metal and / or low carbon charcoal precursor that when charred yields no more than 40% by weight of carbon in a cured base. When a metal catalyst is used, the amount of catalyst metal after the subsequent carbonization step is not larger than about 1% by weight based on the carbon. The mixture is cured, and the carbon precursors are carbonized and activated to produce mesoporous activated carbon.

DETAILED DESCRIPTION OF THE INVENTION This invention relates to the manufacture of mesoporous activated carbon by the combination of a high carbon charcoal precursor, a low yield carbon additive and / or catalyst metal compound followed by curing, carbonization and finally carbon activation by heat treatment in activation agents such as steam and carbon dioxide, etc. When a catalyst metal compound is used, the amount of catalyst metal supplied is not greater than 1% based on the carbon that is present after the carbonization step. According to this invention, mesoporous carbon means that at least about 50%, and more typically about 60% to 90% of the total pore volume is in the range of 20 to 500 angstroms and not more than 25% pore volume is on the large pore scale (>500 angstroms). By carbon precursor it means a synthetic polymeric substance containing carbon that is converted to a continuous carbon structure with heating. A carbon precursor is preferred over activated carbon particles because as a result of curing, carbonization and activation, the carbon atoms are arranged in a continuous uninterrupted structure of random three-dimensional graffiti platelets. By high performance carbon precursor means that in curing, the precursor that yields more than 40% of the cured resin is converted to carbon in carbonization. For purposes of this invention, a particularly useful high-performance carbon precursor is a precursor of synthetic polymeric carbon, for example a synthetic resin in the form of a solution or liquid of low viscosity at ambient temperatures or capable of being liquefied by heating or other media. The synthetic polymeric carbon precursors include any liquid or liquefiable carbonaceous substance. Examples of useful carbon precursors include thermosetting resins and some thermoplastic resins. Low viscosity carbon precursors (thermosetting resins) are preferred for coating applications because their low viscosity allows a greater penetration into the substrate. The typical resin viscosity is in the range of 50 to 100 cp. Any high-performance carbon resin can be used. Phenolic and furan resins are the most suitable. Phenolic resins are most preferred because of their low viscosity, high carbon yield, high degree of entanglement with curing relative to other precursors, and low cost. Suitable phenolic resins are resin resins such as polyphenol resin 43250 and 43290 from Occidental Chemical Corporation, and Durite resin resin from Borden Chemical Company. A particularly suitable furan liquid resin is Furcab-LP from QO Chemicals Inc. The carbon precursor may include a single high-performance carbon precursor material, or a mixture of two or more precursor materials. Optionally, the activated carbon already manufactured can be added to the liquid carbon precursor to adjust the viscosity of the precursors for forming or forming structures.

To obtain coal of the desired porosity, a catalyst metal and / or a low carbon charcoal precursor is included with the high carbon charcoal precursor. The low carbon charcoal precursor is that which when charred has a carbon yield of no more than about 40% on a cured base. Some especially useful carbon low carbon precursors are interlinking additives such as glycerin, melamine formaldehyde, epoxy and / or polyvinyl alcohol. An advantage of using the low carbon charcoal precursor alone without the catalyst metal is that the step of removing the catalyst metal in cases where a catalyst metal is not desired in the final product, is eliminated. When the catalyst metal is present in the carbon matrix, the topographic effects of surface engraving, channeling and engraving pitting are induced by each individual metal additive during activation, depending on its own physical and chemical properties, carbon structures, and reaction conditions. To selectively generate desirable mesoporous activated carbon, those three actions are coordinated to provide the desired pore size. Channeling and stings provide an opportunity to produce pores, and surface engraving provides an opportunity for pore elongation. The suitable catalyst metal may be an alkaline, alkaline earth, transitional, and / or noble metal. Advantageously, the catalyst metals are Pt, Pd, Rh, Ag, Au, Fe, Re, Sn, Nb, V, Zn, Pb, Ge, As, Se, Co, Cr, Ni, Mn, Cu, Li, Mg, Ba, Mo, Ru, Os, Go, Ca, and or combinations of them. The preferred metals are Pt, Co, Ni, and / or Fe, especially Fe in the oxidation state +3; with Co being especially preferred. The metal catalyst is preferably in the form of a precursor or compound, for example organic or inorganic salt of a catalyst metal, which decomposes the catalyst metal or catalyst metal oxide in heating, such as sulfates, nitrates, etc. A metal compound, preferably finely dispersed, is preferred to the elemental form because the metal powder tends to form larger grains of graffiti regions instead of the favored opposite effect. Examples of compounds are oxides, chlorides, (except alkaline or alkaline torrids) nitrates, carbonates, sulfates, complex of ammonium salts, etc. The organometallic compounds of the appropriate type metals can be used with or without the low carbon charcoal precursor. For example, acetates such as cobalt acetate and / or acetylacetonates such as cobalt, platinum, and / or iron acetylacetonate are especially suitable. Although not wishing to be bound by theory, it is believed that the bulky organic structure introduced to the resin is thermally fixed after curing to the matrix and can help to form more porosity when those structures are removed during carbonization. Therefore, more catalysts are exposed to the surface for additional pore size engineering during the activation step.

The amount of metal catalyst used in the invention depends on the type or activity of the metal catalyst, as well as the final porosity and desired pore size distribution, but is not greater than about 1%, and typically from about .01% to 1%, and more typically about 0.01% to 0.2% by weight based on the carbon present after carbonization. For highly active Co, the concentration may be low as 50 to 100 ppm. The amount of metal addition significantly affects the final pore structures generated. Adding too much metal, however, will cause a significant increase in the rate of concretion of the metal. The concreted particles tend to block the pores and form the so-called bottleneck pores. furtherWhen the concretion occurs, the activity of the catalysts falls and is still deactivated. In some cases it is desirable to include a catalyst metal and a low carbon charcoal precursor as the additives. For example, combinations of cobalt, for example, cobalt acetate or nitrate and / or iron compounds, for example iron nitrate, with the above interlinking additives are useful. Particularly advantageous are combinations of cobalt acetate or acetyl acetonate of iron with glycerin and / or polyvinyl alcohol. A useful method for making the mesoporous activated carbon is to coat an inorganic substrate such as a honeycomb with a suspension or coating solution of the carbon precursor and the metal catalyst compound, followed by curing, carbonization, and activation of the carbon to form a coating. continuous activated carbon. For example, about 7 g of catalyst precursor, Co (II) nitrate is first dissolved in a small amount of water, and then placed in 1000 ml of low viscosity phenol resin resin. The mixture is homogenized to form a uniform solution. The suspension or solution is then coated on a substrate, for example a monolithic substrate such as one made of cordierite. This is then cured at about 150 ° C, after drying at about 90-100 ° C and then carbonized and activated in activation agents such as carbon dioxide or steam. The substrate has an outer surface from which the pores extend towards the substrate. The coating penetrates and is distributed through these pores as a coating on them. In its most useful form the monolithic substrate has means for the passage of a fluid stream through it, for example, a network of pores communicating from outside to inside, and / or channels extending from one end of the monolith to the other. another for the passage of the fluid flow at one end and out through the other end. The substrate must have sufficient strength to function in the application and be able to withstand the heat treatment temperature experienced in the formation of the activated carbon coating. It is desirable that the total open porosity of the substrate is at least about 10%, preferably larger than 25% and more preferably larger than 40%. For most purposes, the desirable porosity scale is approximately 45% to 55%. Preferably the pores of the substrate material create "interconnected porosity" which is characterized by pores that connect in and / or intersect other pores to create a tortuous network of porosity within the substrate. Suitable porous substrate materials include ceramics, glass ceramics, glass, metal, clays, and combinations thereof. By combinations means physical or chemical combinations, for example, mixtures, compounds, or composite bodies. Some materials that are especially suitable for the practice of the present invention, although it should be understood that the invention is not limited to such, are those made of cordierite, mulite, clay, magnesia, and metal oxides, talcum, zirconia, zirconia, zirconates, zirconia spinels, aluminosilicate silicates, spinels, alumina, silica, silicates, borides, aluminosilicates, for example, porcelains, lithium aluminosilicates, silica alumina, feldspar, titania, fused silica, nitrides, borides, carbides, example silicon carbide, silicon nitride or mixtures thereof. Cordierite is preferred because its coefficient of thermal expansion is comparable to that of carbon, increasing the body's stability of activated carbon. Some typical ceramic substrates are described in the U.S. Patents. 4,127,691 and 3,885,977. Those patents are incorporated herein by preference as presented.

Suitable metallic materials are any metal or alloy or intermetallic compound that provides a durable structural service, and does not soften below about 600 ° C. Particularly useful alloys are predominantly those of the iron group metal (ie Fe, Ni, and Co) either with carbon (for example steels, especially stainless or high temperature steels) or without carbon. The most typical of the last alloys for higher temperature service are those that consist essentially of the metal of the iron and aluminum group, with the metal of the iron group preferred being iron. Especially preferred is Fe, Al, and Cr. For example, powders of Fe5-20A15-40Cr, and Fe7-10A110-20Cr with other possible additions are especially suitable. Some typical compositions of metal powders for substrate formation are described in the U.S. Patents. 4,992,233, 4,758,272, and 5,427,601 which are incorporated herein by reference as presented. The patents of E.U.A. 4,992,233 and 4,758,272 relate to methods for producing porous concreted bodies made from Fe and Al metal powder compositions with optional additions of Sn, Cu, and Cr. The U.S. 5,427, 601 refers to porous concretes having a composition consisting essentially of, in percent by weight, about 5 to 40 Cr, about 2 to 30 Al, 0 to about 5 of special metal, of 0 to 4 of additive of Rare earth oxide and the rest being iron group metal and unavoidable impurities, with the metal of the iron group preferred being iron. When the rare earth oxide is present, the special metal is at least one of Y, lanthanides, Zr, Hf, Ti, Si, alkaline earth metal, B, Cu, and Sn. When rare earth oxide is not present, the special metal is at least one of Y, lanthanide, Zr, Hf, Ti, Si, and B, with optional additions of alkaline earths, Cu, and Sn. The substrate is preferably a honeycomb or thin-walled matrix that forms a multiplicity of open-ended cells that extend between the ends of the honeycomb. In general, the cell densities of the honeycomb are in the range of 235 cells / cm2 to 1 cell / cm2. Some examples of combs commonly used in addition to those, although it should be understood that the invention is not limited to such, are approximately 94 cells / cm2, approximately 62 cells / cm2, or approximately 47 cells / cm2, and those that have approximately 31 cells / cm2. Typical wall thicknesses are, for example, approximately 0.15 mm for honeycombs of approximately 62 cells / cm2. The wall thicknesses (network) are typically in the range of 0.1 to 1.5 mm. The size and exterior shape of the body is controlled by the application. Cordierite honeycombs are especially preferred as substrates for mesoporous activated carbon. The contact is made by any suitable method to bring the carbon precursor and the metal catalyst into intimate contact with the inorganic substrate. Illustrative methods of contact include immersing the substrate in the solution or suspension of the carbon precursor (s) (with or without catalyst metal), or spraying the solution or suspension of the carbon precursor (s) (with or without catalyst metal) directly on the substrate. Another useful method for manufacturing the activated carbon with catalyst metal is to form a mixture of the carbon precursor (s), (with or without catalyst metal), binders and / or fillers, and forming aids, such as by extrusion. Some binders that may be used are temporary plasticizing binder such as cellulose ethers. Some typical cellulose ethers are methylcellulose, ethylhydroxyethylcellulose, hydroxybutylcellulose, hydroxybutylmethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, hydropropylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, sodium carboxymethylcellulose., and mixtures thereof. Methylcellulose and / or methylcellulose derivatives are especially suitable as organic binders in the practice of the present invention with methylcellulose, hydroxypropylmethylcellulose or combinations thereof being preferred. Some fillers that are suitable include natural and synthetic fillers, hydrophobic, and hydrophilic, fibrous and non-fibrous carbonizable and non-carbonizable. For example some natural fillers are soft woods, for example pine, spruce, red sequoia, etc., hardwoods for example ash, beech, birch, maple, oak, etc., sawdust, bark fibers for example, almond bark, coconut bark, apricot bark, peanut bark, hryoria bark, walnut bark, etc., cotton fibers such as cotton linters, cotton cloth, cellulose fibers, cottonseed fiber, split vegetable fibers for example, hemp, coconut fiber, jute, henequen, and other materials such as corn cob, citrus pulp (dried), soybean meal, marsh moss, wheat flour, wool fibers, corn, potato, rice, Tapioca, coal dust, activated carbon powder, etc. Some synthetic materials are regenerated cellulose, rayon cloth, cellophane, etc. Some examples of carbonizable fillers that are especially suitable for liquid resins are cellulose, cotton, wood, and henequen, or combinations thereof, all of which are preferably in the form of fibers. Some inorganic fillers that may be used are oxygen-containing minerals such as clays, zeolites, talc, etc., carbonates, such as calcium carbonate, aluminosilicates such as kaolin (an aluminosilicate clay), fly ash (an aluminosilicate ash obtained after incineration of carbon in power plants), silicates, for example volastonite (calcium metasilicate), titanates, zirconates, zirconia, zirconia spinels, aluminum magnesium silicates, mulite, alumina, alumina trihydrate, spinels, feldspar, attapulgite, and fibers of aluminosilicate, cordierite powder, etc.

Some examples of especially suitable inorganic fillers are cordierite powder, talcs, clays, and aluminosilicate fibers. The organic fillers provide additional support to the formed structure and introduce wall porosity in the carbonization because in general they leave very little carbon residue. Some organic fillers are polyacrylonitrile fibers, polyester fibers (fluff), nylon fibers, polypropylene fibers (fluff) or dust, acrylic fibers or powders, aramid fibers, polyvinyl alcohol, etc. Some binders and fillers that are especially suitable are described in the patent application of E.U.A. SN 08 / 650,685, filed May 20, 1996. This application is incorporated herein by reference. Some training aids, for example extrusion, are soaps, fatty acids such as oleic acid, linoleic, etc., polyoxyethylene-stearate, etc., or combinations thereof. Especially preferred is sodium stearate. The optimized amounts of extrusion aids depend on the composition and the binder. The carbon precursor and the metal catalyst (if present), mixed with the correct amounts of the gradients mentioned above are then subjected to heat treatments to convert the carbon precursor to continuous carbon (carbonize). The resulting carbon is then heat treated to activate the carbon and produce an activated carbon structure.

When the carbon precursor is a thermosetting resin, the carbon precursor is cured before activation and more typically before carbonization. Healing is typically achieved by heating the precursor at temperatures of about 100 ° C to 200 ° C for 0.5 to 5.0 hours. Healing is usually done in air at atmospheric pressures. When certain precursors (for example, furfuryl alcohol) are used, curing can be achieved by adding a curing catalyst such as an acid catalyst at room temperature. The cure also serves to retain the uniformity of the distribution of the metal compound catalyst in the carbon. Carbonization is the thermal decomposition of the carbonaceous material and the incorporated metal catalyst compound (if present), thereby eliminating low molecular weight species (e.g., carbon dioxide, water, gaseous hydrocarbons, etc.) and producing a fixed carbon mass and a rudimentary pore structure in coal. Said conversion or carbonization of the cured carbon precursor is typically achieved by heating to a temperature in the range of 400 ° C to 800 ° C for 1 to 10 hours in a reducing or inert atmosphere (for example, nitrogen, argon, helium, etc.). .). The curing and carbonization of the carbon precursor results in substantially uninterrupted carbon with uniformly dispersed catalyst particles (if present) in the carbon body. The catalyst is usually added to larger particles, different from the cured structures, where the catalyst is dispersed in a molecular manner. The size of the catalyst particle depends on the amount added to the starting resin. The more catalyst there is in the initial resin, the catalyst particle is more easily added. The size of the catalyst particle also depends on the carbonization and activation temperature. Higher temperatures of carbonization and activation induce a significant metal concretion even when the metal concentration is relatively low. Where the carbon is in the form of a coating, the carbon coating is anchored in the porosity of the substrate and as a result is highly adherent. The upper surface of the carbon coating is an uninterrupted layer of carbon-to-carbon bonds. If the interconnecting porosity is present in the substrate, a carbon interconnection network will be formed within the composition, resulting in an even more adherent carbon coating. The uninterrupted carbon coating extending over the outer surface of formed substrate provides a structure with advantages of high catalytic capacity despite relatively low carbon content, high strength, and high usage temperatures. Carbon containing structures can be formed in an amount of less than and up to 50%, often less than and up to 30% of the total weight of the substrate and carbon. The curing and carbonization of the catalyst metal compound in the carbon precursor results in a uniform and intimate chemical bond of catalyst with uninterrupted carbon structure. The resulting catalyst particle size, controlled by catalyst loading, processing parameters, and catalyst nature, etc., is a primary factor in determining the pore sizes in the activated carbon. The well dispersed and uniform catalyst particle size can help develop mesopores in the activated carbon in the last activation step. Activation is done in a catalytic manner to create substantially new porosity in the mesoporous size scale, as well as to enlarge the diameter of the micropores formed and thus increase the pore volume. The formation of micropores without the aid of metal catalyst or the low carbon charcoal precursor according to this invention is normally unavoidable. In general, the activation can be carried out by standard methods, in carbon dioxide or steam at 400-900 ° C. If the activation is in steam, the temperatures are preferably 400 ° C to 800 ° C. The lowest carbonization and activation temperature is preferred when carbonizing and activating resins containing catalyst. In the carbonization stage, a low temperature not only helps to form less-sized large metal particles, but also contributes to the formation of a relatively less condensed carbon structure. Both factors are very important for the subsequent pore generation during the activation step. For the same reason, a lower activation temperature is preferred. From this point of view, activation in steam is more preferred than activation in carbon dioxide, due to the requirement of lower vapor temperatures due to its higher reaction rates. The presence of a catalyst provides new catalytic active sites to begin pore formation in activation procedures instead of only carbon sites in non-catalytic activation. The activation reaction of catalytic carbon is faster than the activation of non-catalytic carbon. Due to the difference in reaction velocity between catalytic and non-catalytic modes, catalytic activation becomes overwhelmingly predominant over non-catalytic activation under activation conditions. In addition, the presence of catalyst induces topographic effects on pore formation during catalytic activation. Depending on the reaction conditions and the nature of the catalyst on the surface of the coal, pores larger than 30 angstroms can be generated selectively. According to one embodiment, the metal catalyst is Pt, for example in the form of dihydrogenchloroplatinic acid and the activation temperature is about 650 ° C to 750 ° C in steam. Such conditions produce activated carbon having approximately 60% to 95% of the total porosity on the mesoporous scale, and approximately 80 to 90% of the mesoporous volume on the pore size scale of approximately 40 to 300 angstroms. According to another embodiment, the catalyst metal is Co, for example in the form of cobalt nitrate and the activation temperature is from about 650 ° C to 750 ° C in steam. These conditions produce activated carbon that has approximately 60 to 85% of the total porosity in the mesoporous scale, and approximately 60 to 90% of the mesoporum volume is on the pore size scale of approximately 100 to 400 angstroms. According to yet another embodiment, the catalyst metal is Fe, particularly in the oxidation state +3, for example in the form of iron nitrate hexahydrate and the activation temperature is from about 650 ° C to 800 ° C in steam. Such conditions produce activated carbon that has approximately 80 to 95% of the total porosity that is on the mesoporous scale, and approximately 85 to 95% of the mesoporous volume is on the pore size scale of 30 to 60 angstroms. Coal precursors based on synthetic polymer, such as phenolic resin, typically form hard coal (also called animal or bone char) with short scale graffitic microcrystalline structures after carbonization in an inert atmosphere. The animal carbon that forms is very rich carbon with a small amount of porosity produced during the removal of volatile products. While not wishing to be bound by theory, it is believed that the increase in pore sizes in coal brought about by the addition of metal in the form of organ and inorganometallic compounds and activating animal carbon using steam or carbon dioxide is due to: ) The increase in turbostimatic nature of the resulting animal charcoal even before activation. In other words, finely dispersed metal compounds promote the formation of even more disordered structure during carbonization that could otherwise occur. 2) The metal compounds are reduced to the metallic state after carbonization. They are highly active and promote the activity of coal in their vicinity. The larger pores are therefore generated around the catalyst. The catalytic activation with the metal additives significantly increases the activation speed. Moreover, the activation is preferably carried out in the immediate vicinity of the metal particles. As the catalyst particles are drilling, forming channels and etching the surface through the carbon body, the size of the pores formed (channels and holes) is equivalent to or larger than the size of the catalyst particles. By adjusting the particle size of the catalyst, mesopores and even macropores can be produced selectively. (3) Activation in steam is preferred to carbon dioxide. The steam produces a wider porous texture and a more mesoporous carbon and requires a much lower temperature than CO2. The catalytic metals, if present, can be removed from the resulting mesoporous activated carbon body, or they can remain if needed in catalytic operations, etc. The removal is done by treating the body with a liquid phase agent that will leach the metal in solution and the metal will be washed. These agents are acids and bases, like nitric, which will leach most metals. Hydrochloric acid instead of nitric acid works effectively for metals, which form coordination compounds with chloride as platinum. Acetic acid can be used for species that easily form acetates. If the carbon surface is oxidized, such as if nitric acid or other oxidizing agent is used, it can be subjected to a subsequent treatment at elevated temperatures in nitrogen or hydrogen to produce a reduced surface area. The removal of metal can also be done by treating the body with heat or a gas phase agent which will form volatile metal compounds and the volatile compounds formed will be released in the gas phase by heating. Said agents are carbon monoxide, hydrogen and chlorine, etc., depending on the nature of the metal catalyst. The alkali metal can be removed directly from the carbon body by heat treatment due to its high volatility. Metals like nickel, iron, cobalt, etc., can be removed through their volatile carbonyl compounds formed with carbon monoxide. To more fully illustrate the invention, the following non-limiting examples are presented. All parts, portions, and percentages are on a weight basis unless stated otherwise.

EXAMPLES OF METAL CATALYST.

COMPARATIVE EXAMPLE 1 Low viscosity phenolic resin of approximately 100 to 150 cp was coated by immersion on ceramic cordierite honeycombs having approximately 50% open porosity. They were then dried at 95 ° C, cured at 150 ° C, carbonized at 750 ° C in N2 and activated in CO2 at 900 ° C for various periods of time. The percentage of pores in each of the three scales was determined on a volume basis using N2 absorption. The percentage of pore volume in the micropore scale was determined using the standard t method. The percentage of mesopore volume was determined using the BJH method. The resulting activated carbons exhibit mainly the characteristics of microporous carbons. More than 80% of pore volume is on the micropore scale. The surface areas are at least above 1000 m2 / g of coal. Although as the level of incineration in the activation increases, the percentage of mesopores increases slightly, the magnitude of increase is small compared to the level of coal being incinerated. The manufacture of conventional activated carbon tends to produce predominantly microporous carbon, regardless of how high the incineration is. The surface area increased significantly with the level of incineration. Pore size distributions do not tend to change much with the increase in incineration. In the incineration scale of the example, the activation is a fixed reaction of coal state removal.

EXAMPLE 2 INVENTIVE Ferric nitrate was used as the catalyst metal. Approximately 7 g of ferric nitrate was added to a small amount of water. After it was completely dissolved, it was mixed in 1000 ml of phenolic resin resin (the same resin as above) and vigorously stirred to ensure homogeneous dispersion of the catalyst precursor. The metal-containing mixture was dip coated using a cordierite honeycomb having approximately 50% open porosity and then dried at 95 ° C and cured at 150 ° C, charred at 700 ° C for 1 hour in N2, and activated at 700 ° C for a period of 1 to 4 hours in a mixture of steam and nitrogen. The resulting sample of activated carbon was analyzed using isothermal absorption of N2 for pore size distribution. The resulting activated carbon is mainly mesoporous, the mesoporous content being 80-90% of the total porosity. The carbon had approximately 10% micropores and macropores. The majority of pores in the mesoporous scale is approximately 30 to 60 angstroms (85% mesopores) with a maximum point at 38 angstroms. The surface area of the mesoporous coal is in the range of 500 to 650 m2 / g of carbon. There is a significant drop in the total surface area in catalyst-assisted activation, indicating the presence of larger pores. The amount of microporosity fell significantly with the addition of catalysts. The amount of mesoporosity tends to increase with the level of incinerated charcoal. The carbon containing Fe produced a mesoporous coal with a maximum point of about 38 angstroms on the mesoporous scale.

EXAMPLE 3 INVENTIVE Cobalt nitrate was used as the catalyst metal. Approximately 7.0 g were used, following the same procedure as in example 2. The resulting activated carbon had approximately 70 to 80% mesopores and 20 to 25% macropores. The surface areas are on the scale of 450 to 550 m2 / g of coal. The coal containing cobalt produced a bi-modal distribution on the mesoporous scale, with maximum points centered at approximately 38 and 250 angstroms.

EXAMPLE 4 INVENTIVE The procedure of Example 2 was followed, except that the added metal compounds were reduced to approximately 2.8 grams, in addition the activations were conducted at 700 ° C in a mixture of steam and nitrogen. The resulting activated carbon had 60% mesopores and 25% macropores, with a surface area of approximately 600 m2 / g. This carbon also had a single maximum point on the mesoporous scale at 250 angstroms. The size of the maximum point is such that approximately 75% of the volume of mesoporum was in the pores on the scale of 100 to 400 angstroms.

EXAMPLE 5 INVENTIVE Dihydrogenchloroplatinic acid (CPA) was used as the catalyst metal. Approximately 5 g of CPA were added following the same procedure as in examples 2 and 3. The resulting activated carbon had approximately 70% mesoporous and 10% macropore content, with a surface area close to 550 m2 / g. This coal had a characteristic maximum point on the mesoporous scale centered at 100 angstroms. The maximum point size is such that approximately 80% of the mesopore volume was in the pore scale of 40 to 300 angstroms.

COMPARATIVE EXAMPLE 6 Phenolic ring resin from Occidental Chemical Co., Niagara Falls, N.Y. it was coated on a Cordierite honeycomb and then dried at 90 ° C, cured at 125-150 ° C, and carbonized in nitrogen at 900 ° C and activated in carbon dioxide at 900 ° C. The pore size distribution of the resulting carbon was measured on a Micrometrics (Norcross, Ga.) ASAP 2000 equipment through isothermal nitrogen absorption measurement. The carbon is essentially all microporous with all pores in the scale of 10 angstrom or lower.

EXAMPLE 7 INVENTIVE Example 6 was repeated except that about 1% acetyl acetonate iron was added to the resin before coating. The coated honeycomb was cured, carbonized, and activated in carbon dioxide.

Approximately 60% of the mesoporos present have an average pore size of approximately 90 angstroms.

COMPARATIVE EXAMPLE 8 An extruded resin honeycomb was manufactured by mixing 55.6% phenol resole from Borden, Inc. with approximately 14.7% cordierite silicon dioxide, approximately 22.2% cellulose fiber, approximately 2% phosphoric acid, approximately 4.6% Methocel® , and 0.9% sodium stearate. The mixture was extruded and then the resulting honeycomb was dried at 90 ° C, cured, charred, and activated at 900 ° C in carbon dioxide. The pore size distribution shows essentially all the microporous carbon with an average pore size of 5 angstroms and little or no mesoporosity.

EXAMPLE 9 INVENTIVE The experiment of example 8 was repeated but with approximately 1% cobalt acetate added to the resin before mixing. The sample was processed as in example 8. The pore size distribution shows 70% volume at 400 angstroms.

EXAMPLE 10 INVENTIVE The procedure of Example 6 was repeated, but approximately 50% glycerin and 1% cobalt acetate based on the total coating liquid was added to the resin. With the coating and processing as in example 6, the pore size distribution shows 70% volume of mesoporum with an average pore size of 500 angstroms. Only 20% of the volume is on the micropore scale.

EXAMPLE 11 INVENTIVE In an experiment similar to that of Example 10, about 20% polyvinyl alcohol was added to the phenolic ring and then about 1% cobalt acetate was added before coating. The sample was processed as in Example 6, and the pore size distribution showed approximately 69% of the volume on the mesoporous scale and approximately 33% on the micropore scale.

EXAMPLE 12 INVENTIVE Approximately 34% of melamine formaldehyde was added to the resin and the procedure of Example 11 was repeated. The pore size distribution showed 50% of the pores in the mesoporous scale with an average mesoporous size of 70 angstroms. Examples 6-12 above show that either by adding an iron or cobalt salt or an entanglement additive such as glycerin, melamine formaldehyde or polyvinyl alcohol, the pore size distribution can be modified to obtain large pores, for example larger ones of 50 angstroms, which would not otherwise be formed in carbon based on phenolic resole.

EXAMPLE 13 (COMPARATIVE) A batch containing liquid phenolic resin Durite de Borden, Inc. at 55.5%, cellulose fiber BH40 at 22.2%, cordierite silicon dioxide at 14.7%, Methocel® at 4.7%, sodium stearate at 0.9%, and phosphoric acid at 2% was mixed in a crushing hammer and then extruded into a honeycomb shape with approximately 400 cells / 2.54 cm 2 and a wall thickness of approximately 304.8 microns. The sample was then dried at 90 ° C and then cured at 125-150 ° C. The carbonization was carried out under nitrogen at 900 ° C for 6 hours and the activation was carried out in carbon dioxide at 850 ° C for 4 hours. The pore size distribution of the resulting honeycomb is in the range of 2-20 angstroms. No pores larger than 20 angstroms are present.

EXAMPLE 14 (INVENTIVE) To the batch of example 13, cobalt acetate was added at a level of 1%. The sample was then cured, carbonized, and activated in carbon dioxide at 750 ° C for 4 hours. The activation temperature was reduced because cobalt promotes carbon gasification and at 850 ° C very uncontrolled incineration takes place. There is a large pore volume on the 50-110 angstrom scale proving that mesoporous carbon combs can be manufactured using catalysts.

Said mesoporous bodies, for example, honeycombs, are useful as catalyst supports in chemical or petrochemical reactors or for applications of water adsorption or purification.

COMPARATIVE EXAMPLE 15 Approximately 16.59 g of nickel nitrate were first dissolved in 50 ml of water and then mixed in 1000 ml of phenolic resin. This high metal content resin was used for dip coating to make carbon coated honeycombs according to a similar procedure to example 2. The metal content in the final carbon was higher than 1% by weight. The final porous carbon had a pore size distribution of 37% micropore, 28% mesoporous, and 35% macropore. Significantly larger pores are produced as a result of high catalyst metal content. It should be understood that although the present invention has been described in detail with respect to certain specific and illustrative embodiments thereof, it should not be considered limited to such but may be used in other ways without departing from the spirit of the invention and the scope of the invention. the claims that are attached.

Claims (28)

NOVELTY OF THE INVENTION CLAIMS

1. - A method for manufacturing mesoporous activated carbon, the method comprising: a) forming a mixture comprising a high carbon charcoal precursor which when charred yields more than 40% carbon in a cured base, and an additive selected from the A group consisting of a catalyst metal, a low carbon charcoal precursor, which, when carbonized, yields no more than 40% by weight of carbon in a cured base, and combinations thereof, characterized in that when a catalyst metal is used, the amount of catalyst metal after the subsequent carbonization step is not larger than 1% by weight based on carbon; b) curing the mixture; c) carbonizing the carbon precursors in the mixture; and d) activate the carbon to produce mesoporous activated carbon.

2. A method according to claim 1 further characterized in that the high carbon charcoal precursor is a thermosetting resin.

3. A method according to claim 2 further characterized in that said high carbon charcoal precursor is phenolic resin.

4. - A method according to claim 1 further characterized in that the additive is a catalyst metal.

5. A method according to claim 4 further characterized in that the amount of catalyst metal is 0.01% to 0.2% by weight based on the carbon.

6. A method according to claim 4 further characterized in that the catalyst metal is provided as a compound selected from the group consisting of alkali metal, alkaline earth metal, transition metal, noble metal, and combinations thereof.

7. A method according to claim 6 further characterized in that the catalyst metal is selected from the group consisting of Co, Fe, Ni, Pt, and combinations thereof.

8. A method according to claim 4 further characterized in that the catalyst metal is provided in the form of an organometallic compound.

9. A method according to claim 8 further characterized in that the organic compound is selected from the group consisting of cobalt acetate, iron acetylacetonate, and combinations thereof.

10. A method according to claim 1 further characterized in that the additive is a precursor of low carbon charcoal.

11. - A method according to claim 10 further characterized in that said carbon low yield carbon precursor is selected from the group consisting of glycerin, melamine formaldehyde, epoxy, polyvinyl alcohol and combinations thereof.

12. A method according to claim 1 further characterized in that the additive is a combination of low carbon charcoal precursor and catalyst metal.

13. A method according to claim 12 further characterized in that the catalyst metal is provided as a compound of a metal selected from the group consisting of iron, cobalt, and combinations thereof.

14. A method according to claim 13 further characterized in that the catalyst metal is provided as cobalt acetate and the low carbon charcoal precursor is selected from the group consisting of glycerin, polyvinyl alcohol, and combinations thereof.

15. A method according to claim 1 further characterized in that the carbon precursor and the additive are applied as a coating on a substrate.

16. A method according to claim 15 further characterized in that the substrate is a honeycomb.

17. - A method according to claim 1 further characterized in that the carbon precursor and the additive are combined with binders and formed in a body.

18. A method according to claim 17 further characterized in that the formation is made by extrusion.

19. A method according to claim 18 further characterized in that the carbon precursor, the additive and the binder are extruded in a honeycomb.

20. A method according to claim 1 further characterized in that the activation is carried out in an atmosphere selected from the group consisting of steam, and carbon dioxide.

21. A method according to claim 20 further characterized in that the activation is carried out in steam.

22. A method according to claim 21 further characterized in that the activation temperature is approximately 400 ° C to 800 ° C.

23. A method according to claim 22 further characterized in that a catalyst metal is used and the catalyst metal is Pt, and the activation temperature is about 650 ° C to 750 ° C.

24. A method according to claim 22 further characterized in that a catalyst metal is used, and the catalyst metal is Co, and the activation temperature is 650 ° C to 750 ° C.

25. - A method according to claim 22 further characterized in that a catalyst metal is used and the catalyst metal is Fe provided in the +3 state, and the activation temperature is 650 ° C to 800 ° C. 26.- Activated carbon produced by the method according to claim 23 having a porosity characterized in that approximately 60% to 95% of the total porosity is on the mesoporous scale, and approximately 80% to 90% of the mesoporous volume is on the pore size scale from 40 to 300 angstroms. 27. Activated carbon produced by the method according to claim 24 having a porosity characterized in that approximately 60 to 85% of the total porosity is in the mesoporous scale and because approximately 60 to 90% of the mesoporous volume is in the pore size scale from 100 to 400 angstroms. 28.- Activated carbon produced by the method according to claim 25 having a porosity characterized in that approximately 80 to 95% of the total porosity is in the mesoporous scale, and because approximately 85 to 95% of the mesoporous volume is in the pore size scale from 30 to 60 angstroms.