Title of Invention	HIGH-PERFORMANCE ADSORBENTS BASED ON ACTIVATED CARBON AND A PROCESS FOR PRODUCING THE SAME
Abstract	The invention concerns high-performance adsorbents based on activated carbon of high meso- and macroporos- ity which are present in the form of discrete grains of activated carbon, wherein • at least 55% of the total pore volume of the high-performance adsorbents are formed by pores (i.e. meso- and macropores) having pore diame- ters of more than 20 Å, • the high-performance adsorbents have a measure of central tendency pore diameter of more than 25 Å, and • the high-performance adsorbents have a BET sur- face area of at least 1250 m2/g. These high-performance adsorbents are obtainable by a novel process comprising specific two-stage activation, and have, in addition to the aforementioned properties, an excellent abrasion and bursting resistance, so that they are useful for a multiplicity of different appli- cations.

Title of Invention

HIGH-PERFORMANCE ADSORBENTS BASED ON ACTIVATED CARBON AND A PROCESS FOR PRODUCING THE SAME

Abstract

The invention concerns high-performance adsorbents based on activated carbon of high meso- and macroporos- ity which are present in the form of discrete grains of activated carbon, wherein • at least 55% of the total pore volume of the high-performance adsorbents are formed by pores (i.e. meso- and macropores) having pore diame- ters of more than 20 Å, • the high-performance adsorbents have a measure of central tendency pore diameter of more than 25 Å, and • the high-performance adsorbents have a BET sur- face area of at least 1250 m2/g. These high-performance adsorbents are obtainable by a novel process comprising specific two-stage activation, and have, in addition to the aforementioned properties, an excellent abrasion and bursting resistance, so that they are useful for a multiplicity of different appli- cations.

Full Text	HIGH-PERFORMANCE ADSORBENTS BASED ON ACTIVATED CARBON HAVING HIGH MESO- AND MACROPOROSITY The present invention concerns the adsorption arts. More particularly, the present invention concerns high- performance adsorbents based on activated carbon of high meso- and macroporosity and a process for produc- tion thereof and also the use of these high-performance adsorbents, particularly for adsorptive filtering mate- rials, for the food industry (for example for preparing and/or decolorizing food products, for the adsorption of toxins, noxiants and odors, particularly from gas or air streams, for purifying or cleaning gases, particu- larly air, and liquids, particularly water, for appli- cation in medicine or to be more precise pharmacy, and also as sorptive storage media particularly for gases, liquids and the like. Activated carbon has fairly unspecific adsorptive prop- erties and therefore is the most widely used adsorbent. Legislation as well as the rising sense of responsibil- ity for the environment lead to a rising demand for ac- tivated carbon. Activated carbon is generally obtained by carbonization (also referred to by the synonyms of smoldering, pyro- lysis, burn-out, etc) and subsequent activation of car- bonaceous compounds, preferably such compounds as lead to economically reasonable yields. This is because the weight losses through detachment of volatile constitu- ents in the course of carbonization and through the subsequent burn-out in the course of activation are ap- preciable. For further details concerning the produc- tion of activated carbon, see for example H.v. Kienle and E. Bader, Aktivkohle und ihre industrielle An- wendung, Enke Verlag Stuttgart, 1980. The constitution of the activated carbon produced - finely or coarsely porous, firm or brittle, etc - de- pends on the starting material. Customary starting ma- terials are coconut shells, charcoal and wood (for ex- ample wood wastes), peat, bituminous coal, pitches, but also particular plastics which play a certain part in the production of woven activated carbon fabrics for example. Activated carbon is used in various forms: pulverized carbon, splint coal carbon, granulocarbon, molded car- bon and also, since the end of the 1970s, spherical ac- tivated carbon ("spherocarbon"). Spherical activated carbon has a number of advantages over other forms of activated carbon such as pulverized carbon, splint coal carbon, granulocarbon, molded carbon and the like that make it useful or even indispensable for certain appli- cations: it is free flowing, abrasion resistant or to be more precise dustless, and hard. Spherocarbon is in great demand for particular applications, for example, because of its specific form, but also because of its high abrasion resistance. Spherocarbon is mostly still being produced today by multistage and very costly and inconvenient processes. The best known process consists in producing spherules from bituminous coal tar pitch and suitable asphaltic residues from the petrochemical industry, which are oxidized to render them unmeltable and then smoldered and activated. For example, spherocarbon can also be produced in a multistage process proceeding from bitu- men. These multistage processes are very cost intensive and the associated high cost of this spherocarbon pre- vents many applications wherein spherocarbon ought to be preferable by virtue of its properties. WO 98/07655 A1 describes a process for producing acti- vated carbon spherules wherein a mixture comprising a diisocyanate production distillation residue, a carbo- naceous processing aid and if appropriate one or more further additives is processed into free-flowing spher- ules and subsequently the spherules obtained in this way are carbonized and then activated. It is further prior art to produce spherocarbon by smoldering and subsequent activation of new or used ion exchangers comprising sulfonic acid groups, or by smol- dering ion exchanger precursors in the presence of sul- furic acid and subsequent activation, the sulfonic acid groups and the sulfuric acid respectively having the function of a crosslinker. Such processes are described for example in DE 43 28 219 A1 and DE 43 04 026 A1 and also in DE 196 00 237 Al including the German patent- of-addition application DE 196 25 069 A1. However, there are a number of specific applications where it is not only the geometry or to be more precise the external shape of the activated carbon which is of decisive importance, but also its porosity, in particu- lar the total pore volume and the adsorption capacity on the one hand and the distribution of the pores, i.e., the fraction of micro-, meso- and macropores in relation to the total pore volume, on the other. There are a number of applications requiring a particu- larly high meso- and macroporosity of the activated carbon, i.e., a high meso- and macropore volume frac- tion, coupled with an altogether high total pore vol- ume, for example in relation to the applications men- tioned at the beginning, for example for use in the food industry, in the manufacture of certain adsorptive filtering materials (for example for NBC protective ap- parel) , for the adsorption of toxins, noxiants and odors, particularly from gas or air streams, for puri- fying or cleaning gases, such as in particular air, and also liquids, for application in medicine or to be more precise pharmacy, in the sorptive storage of gases or liquids and the like. True, the activated carbon known for this purpose from the prior art does have a certain degree of meso- and macroporosity, but that degree is not sufficient in all cases. In addition, increasing porosity is often ob- served to be accompanied by an unwelcome, occasionally unacceptable decrease in mechanical stability or to be more precise abrasion resistance. Nor are the fraction of the total pore volume which is accounted for by meso- and macropores and the absolute pore volume al- ways sufficient to ensure adequate performance capabil- ity and/or an adequate impregnatability (for example impregnation with metals or metal salts) for all appli- cations. It is therefore an object of the present invention to provide, on the basis of activated carbon, a high- performance adsorbent which is suitable for the afore- mentioned fields of application in particular and which at least substantially avoids or else at least amelio- rates the above-described disadvantages of the prior art. More particularly, the adsorbent to be provided according to the present invention should have a high meso- and macroporosity, i.e., a high meso- and macro- porous fraction in relation to the total pore volume and also a large total pore volume, yet at the same time also good mechanical stability, particularly a high stability to abrasion and bursting. In the context of the present invention, the term "mi- cropores" refers to pores having pore diameters of up to 20 A inclusive, whereas the term "mesopores" refers to pores having pore diameters in the range of more than 20 A (i.e., > 20 Å) to 500 Å inclusive and the term "macropores" refers to pores having pore diameters of more than 500 Å (i.e., > 500 Å): • micropores: pore diametermicropores ≥ 20 Å • mesopores: 20 Å • macropores: pore diametermacropores > 500 Å By way of a solution to the problem described above, the present invention proposes - in accordance with a first aspect of the present invention - high- performance adsorbents based on activated carbon in the form of discrete grains of activated carbon, preferably in spherical form, according to claim 1. Further, in particular advantageous embodiments of the high- performance adsorbents of the present invention are subject matter of the corresponding subclaims. The present invention further provides - in accordance with a second aspect of the present invention - the present invention process for producing the high- performance adsorbents according to the present inven- tion, as more particularly defined in the corresponding process claims. The present invention yet further provides - in accor- dance with a third aspect of the present invention - the present invention use of the high-performance ad- sorbents according to the present invention, as more particularly defined in the corresponding use claims. The present invention accordingly provides - in accor- dance with a first aspect of the present invention - high-performance adsorbents based on activated carbon in the form of discrete grains of activated carbon, preferably in spherical form, these high-performance adsorbents being characterized by the following parame- ters : • a pore volume fraction formed by pores having pore diameters of more than 20 A (i.e., in other words, a meso- and macropore volume fraction) which comprises at least 55% of the total pore volume of high- performance adsorbents (This parameter is inter- changeably also referred to as "fraction of external pore volume in relation to total pore volume".), • a measure of central tendency pore diameter of more than 25 A. • a BET surface area of at least 1250 m2/g, The present high-performance adsorbents or to be more precise activated carbons, in addition to the afore- mentioned properties or to be more precise parameters, particularly a high meso- and macropore volume fraction (i.e., a high pore volume fraction due to pores having a pore diameter of more than 20 Å), are further notable in particular for a large total porosity and a simulta- neously large BET surface area. As will be shown in what follows, the mechanical strength, particularly the abrasion resistance and the bursting or to be more precise compressive strength, of the present high-performance adsorbents is despite the high total porosity extremely high - in contrast to comparable high-porosity activated carbons of the prior art - so that the present high-performance adsorbents or to be more precise activated carbons are also suit- able for applications where they are exposed to large mechanical loads. In relation to all the parameter indications here- inabove and hereinbelow, it is to be noted that the re- cited limits, in particular upper and lower limits, are included, i.e., all statements of values are to be un- derstood as including the respective limits, except where otherwise stated in an individual case. It will further be understood that in an individual case or in relation to an application it may be necessary if ap- propriate to depart slightly from the limits mentioned without leaving the realm of the present invention. The hereinabove and hereinbelow mentioned parameter data are determined using standardized or explicitly indicated methods of determination or using methods of determination familiar per se to one skilled in the art. The parameter data concerning the characterization of the porosity, particularly of the above-specified meso- and macropore fraction (i.e., the fraction of the total pore volume of the high-performance adsorbents which is contributed by pores having pore diameters of more than 20 A) each follow from the nitrogen isotherm of the ac- tivated carbon measured. The measure of central tendency pore diameter is simi- larly determined on the basis of the respective nitro- gen isotherms. The BET method of determining the specific surface area is in principle known as such to one skilled in the art, so that no further details need be furnished in this regard. All BET surface area data are based on the ASTM D6556-04 method of determination. The present in- vention utilizes the Multipoint BET (MP-BET) method of determination in a partial pressure range p/po of 0.05 to 0.1. With regard to further details concerning the determi- nation of the BET surface area or to be precise con- cerning the BET method, reference may be made to the aforementioned ASTM D6556-04 standard and also to Rompp Chemielexikon, 10th edition, Georg Thieme Verlag, Stuttgart/New York, headword: "BET-Methode", including the references cited therein, and to Winnacker-Kuchler (3rd edition), Volume 7, pages 93 ff, and also to Z. Anal. Chem. 238, pages 187 to 193 (1968). As observed above and more particularly specified here- inbelow, one special feature of the high-performance adsorbents of the present invention is that they have a very large total pore volume as determined by the Gur- vich method, to provide a very large adsorptive capac- ity in which the meso- and macropore volume fraction (i.e., that is, the pore volume fraction due to pores having pore diameters above 20 Å) is high, viz. at least 55% of the total pore volume. The Gurvich determination of total pore volume is a method of measurement/determination known per se in this field to a person skilled in the art. For further details concerning the Gurvich determination of total pore volume reference may be made for example to L. Gurvich (1915), J. Phys. Chem. Soc. Russ. 47, 805, and also to S. Lowell et al., Characterization of Po- rous Solids and Powders: Surface Area Pore Size and Density, Kluwer Academic Publishers, Article Technology Series, pages 111 et seq. The Gurvich total pore volume of the high-performance adsorbents of the present invention is at least 0.8 cm3/g, particularly at least 1.0 cm3/g, preferably at least 1.2 cm3/g, and can generally attain values of up to 2.0 cm3/g, particularly up to 2.5 cm3/g, prefera- bly up to 3.0 cm3/g, more preferably up to 3.5 cm3/g. The Gurvich total pore volume of the high-performance adsorbents of the present invention is generally in the range from 0.8 to 3.5 cm3/g, particularly 1.0 to 3.5 cm3/g, preferably 1.2 to 3.2 cm3/g. Owing to their high meso- and macroporosity, the meso- and macropore volume of the high-performance adsorbents of the present invention (i.e., that is, in other words, the pore volume formed by pores having pore di- ameters of more than 20 Å) is relatively high in that in general the carbon black method pore volume of the high-performance adsorbents of the present invention which is formed by pores having pore diameters of more than 20 A (i.e., that is, the meso- and macropore vol- ume) is in the range from 0.4 to 3.3 cm3/g, particularly 0.8 to 3.2 cm3/g, preferably 1.0 to 3.1 cm3/g, more preferably 1.2 to 3.0 cm3/g, most preferably 1.2 to 2.8 cm3/g. The pore volume formed by pores having pore diameters of more than 20 Å is interchangeably also re- ferred to as "external pore volume". Generally at least 60%, particularly at least 65%, preferably at least 70%, more preferably at least 75%, most preferably at least 80% of the total pore volume of the high-performance adsorbents of the present in- vention is formed by the pore volume of pores having pore diameters of more than 20 A (i.e., that is, in other words, by the meso- and macropore volume). Generally 55% to 95%, particularly 60% to 95%, prefera- bly 65% to 90%, more preferably 70 to 85% of the total pore volume of the high-performance adsorbents of the present invention is formed by the pore volume of pores having pore diameters of more than 20 Å. The aforemen- tioned percentages thus identify that proportion of the total pore volume of the high-performance adsorbents of the present invention which is attributable to the fraction of the so-called external pore volume (i.e., the pore volume formed by pores having pore diameters of more than 20 Å) . The carbon black method of determination is known per se to one skilled in the art (as is the corresponding analysis, including plotting and fixing of the p/p0 range) , so that no further details are needed in this regard. In addition, for further details of the carbon black method of determining the pore surface area and the pore volume reference may be made for example to R.W. Magee, Evaluation of the External Surface Area of Carbon Black by Nitrogen Adsorption, Presented at the Meeting of the Rubber Division of the American Chem. Soc, October 1994, for example cited in: Quantachrome Instruments, AUTOSORB-1, AS1 WinVersion 1.50, Operating Manual, OM, 05061, Quantachrome Instruments 2004, Flor- ida, USA, pages 71 ff. Owing to the high meso- and macroporosity of the high- performance adsorbents of the present invention, the measure of central tendency pore diameter is relatively high in that in general it is at least 30 Å, particu- larly at least 35 Å, preferably at least 40 Å. In general, the measure of central tendency pore diame- ter of the high-performance adsorbents of the present invention is in the range from 25 to 75 Å, particularly 30 to 75 Å, preferably 35 to 70 Å, more preferably 40 to 65 Å. As stated above, it is a further special feature of the high-performance adsorbents of the present invention that BET surface area is relatively large and that it is at least 1250 m2/g, preferably at least 1400 m2/g, more preferably at least 1500 m2/g, most preferably at least 1600 m2/g. In general, the BET surface area of the high- performance adsorbents of the present invention is in the range from 1250 m2/g to 2800 m2/g, particularly 1400 to 2500 m2/g, preferably 1500 to 2300 m2/g, more pref- erably 1600 to 2100 m2/g. The carbon black method external pore surface area of the high-performance adsorbents of the present inven- tion (i.e., that is, the pore surface area formed by pores having pore diameters of more than 20 Å) is rela- tively large, because of the high meso- and macropore fraction, and is generally in the range from 200 to 1000 m2/g, particularly 250 to 950 m2/g, preferably 350 to 900 m2/g, more preferably 400 to 850 m2/g. In general, the carbon black method external pore sur- face area of the high-performance adsorbents of the present invention (i.e., that is, the pore surface area formed by pores having pore diameters of more than 20 A) forms up to 30%, particularly up to 40%, prefera- bly up to 50% of the total pore surface area of the high-performance adsorbents of the present invention. More particularly, the carbon black method external pore surface area of the high-performance adsorbents of the present invention (i.e., that is, the pore surface area formed by pores having pore diameters of more than 20 A) forms 10 to 50%, particularly 15 to 45%, prefera- bly 20 to 40% of the total pore surface area of the high-performance adsorbents of the present invention. In addition, the high-performance adsorbents of the present invention have an extremely high butane adsorp- tion and simultaneously an extremely high iodine num- ber, which fact characterizes their property of having excellent adsorption properties with regard to a wide variety of materials to be adsorbed. The ASTM D5742-95/00 butane adsorption of the high- performance adsorbents of the present invention is gen- erally at least 30%, particularly at least 35%, pref- erably at least 40%. In general, the high-performance adsorbents of the present invention have an ASTM D5742- 95/00 butane adsorption in the range from 30% to 80%, particularly 35 to 75% preferably 40 to 70%. The ASTM D4607-94/99 iodine number of the high- performance adsorbents of the present invention is gen- erally at least 1250 mg/g, particularly at least 1300 mg/g, preferably at least 1350 mg/g. The high- performance adsorbents of the present invention pref- erably have an ASTM D4607-94/99 iodine number in the range from 1250 to 2100 mg/g, particularly 1300 to 2000 mg/g, preferably 1350 to 1900 mg/g. The iodine number can be taken as a measure for available surface area provided by predominantly larger micropores; the aforementioned values of the iodine number of the high- performance adsorbents of the present invention show that the high-performance adsorbents of the present in- vention simultaneously also have a high microporosity. Owing to their high meso- and macroporosity, the high- performance adsorbents of the present invention simi- larly have high methylene blue and molasses adsorption numbers which together can be taken as a measure of available surface area provided predominantly by meso- and macropores. The methylene blue number or to be more precise the methylene blue adsorption, which indicates the amount of methylene blue adsorbed per defined amount of adsorbents, under defined conditions (i.e., the number of ml of a methylene blue standard solution decolorized by a defined amount of dry and pulverized adsorbents), relates to larger micropores and predomi- nantly smaller mesopores and gives an indication of the adsorptive capacity of the high-performance adsorbents of the present invention in relation to molecules com- parable in size to methylene blue. By contrast, the mo- lasses number must be considered a measure of the meso- and macroporosity and indicates the amount of adsorb- ents which is required to decolorize a standard molas- ses solution, so that the molasses number gives an in- dication of the adsorptive capacity of the high- performance adsorbents of the present invention in re- lation to molecules that are comparable in size to mo- lasses (generally sugar beet molasses). Together, therefore, the methylene blue and molasses numbers can be considered a measure of the meso- and macroporosity of the high-performance adsorbents of the present in- vention. The methylene blue value of the high-performance ad- sorbents of the present invention which is determined by following the method of CEFIC (Conseil Europeen des Federations des Industries Chimiques, Avenue Louise 250, Bte 71, B - 1050 Brussels, November 1986, European Council of Chemical Manufacturers' Federations, Test Methods for Activated Carbons, Item 2.4 "Methylene blue value", pages 27/28) is at least 15 ml, particularly at least 17 ml, preferably at least 19 ml, and is gener- ally in the range from 15 to 60 ml, particularly 17 to 50 ml, preferably 19 to 45 ml. The methylene blue value according to the afore- mentioned CEFIC method is thus defined as the number of ml of a methylene blue standard solution which are de- colorized by 0.1 g of dry and pulverized activated car- bon. Performing this method requires a glass vessel with ground stopper, a filter and also a methylene blue standard solution prepared as follows: 1200 mg of pure methylene blue dye (corresponding to about 1.5 g of methylene blue to DAB VI [German Pharmacopeia, 6th edition] or equivalent product) are dissolved in water in a 1000 ml volumetric flask, and the solution is allowed to stand for several hours or overnight; to check its strength, 5.0 ml of the solution are diluted with 0.25% (volume fractions) acetic acid to 1.0 1 in a volumetric flask and thereafter the absorbance is meas- ured at 620 nm and 1 cm path length, and it has to be 0.840 ± 0.010. If the absorbance is higher, it has to be diluted with the computed amount of water; if it is lower, the solution is discarded and made up fresh. By way of sample preparation, the high-performance adsorb- ents in the form of granular activated carbon are pul- verized ( at 150°C. Precisely 0.1 g of the spherocarbon is then combined with 25 ml (5 ml) of the methylene blue stan- dard solution in a ground glass flask (A preliminary test has to be carried out to see whether an initial addition of 25 ml of methylene blue standard solution with 5 ml additions or an initial addition of 5 ml of methylene blue standard solution with 1 ml additions can be used.). The flask is shaken until decolorization occurs. Then, a further 5 ml (1 ml) of the methylene blue standard solution are added, and the flask is shaken to the point of decolorization. The addition of methylene blue standard solution is repeated in 5 ml amounts (1 ml amounts) as long as decolorization still occurs within 5 minutes. The entire volume of the test solution decolorized by the sample is recorded. The test is repeated to confirm the results obtained. The volume of the methylene blue standard solution in ml which are just decolorized is the methylene blue value of the high-performance adsorbents. It is to be noted in this connection that the methylene blue dye must not be dried, since it is heat sensitive; rather, the water content must be corrected for purely arithmetically. The dimensionless molasses number can in principle be determined either by following the Norit method (Norit N.V., Amersfoort, Netherlands, Norit Standard Method NSTM 2.19 "Molasses Number (Europe)") or alternatively by following the PACS method (PACS = Professional Ana- lytical and Consulting Services Inc., Coraopolis Penn- sylvania, USA) . In the context of the present inven- tion, the values of the molasses number are determined by following the PACS method. Thus, the PACS method mo- lasses number of the high-performance adsorbents of the present invention is at least 300, particularly at least 350, preferably at least 400, and is generally in the range from 300 to 1400, particularly 350 to 1300, preferably 400 to 1250, most preferably 700 to 1200. Whether by following the Norit method or by following the PACS method, the molasses number is determined by determining the amount of pulverized high-performance adsorbents based on activated carbon that is needed to decolorize a standard molasses solution. Determination is effected photometrically, and the standard molasses solution is standardized against a standardized acti- vated carbon having a molasses number of 245 and/or 350. For further details in this regard, reference can be made to the two aforementioned prescriptive methods. Despite their high porosity, particularly meso- and macroporosity, the high-performance adsorbents of the present invention have a high compressive or bursting strength (resistance to weight loading) and also an ex- tremely high abrasion resistance. The compressive or bursting strength (resistance to weight loading) per grain of activated carbon, in par- ticular per spherule of activated carbon, is thus at least 5 newtons, in particular at least 10 newtons and preferably at least 15 newtons. In general, the com- pressive or bursting strength (resistance to weight loading) per grain of activated carbon, particularly per spherule of activated carbon, ranges from 5 to 50 newtons, in particular from 10 to 45 newtons and preferably from 15 to 40 newtons. As mentioned, the abrasion hardness of the high- performance adsorbents of the present invention is also extremely high in that the abrasion resistance when measured by the method of CEFIC (Conseil Europeen des Federations des Industries Chimigues, Avenue Louise 250, Bte 71, B - 1050 Brussels, November 1986, European Council of Chemical Manufacturers' Federations, Test Methods for Activated Carbons, Item 1.6 "Mechanical Hardness", pages 18/19) is always 100% or virtually 100%. Similarly, when measured according to ASTM D3802 abrasion resistances of the high-performance adsorbents of the present invention of 100% or virtually 100% are always obtained. Therefore, the applicant company has developed a modi- fied test method on the lines of this CEFIC method in order that more meaningful values may be obtained. The modified method of determination provides a better simulation of the resistance of the sample or to be more precise of the high-performance adsorbents to abrasion or attrition under near actual service condi- tions. For this purpose, the sample is exposed to stan- dardized conditions for a defined time in a horizon- tally swinging grinding cup charged with a tungsten carbide ball. The procedure adopted for this purpose is as follows: 200 g of a sample are dried for one hour at (120 ± 2) °C in a circulating air drying cabinet (type: Heraeus UT 6060 from Kendro GmbH, Hanau) and are subse- quently cooled down in a desiccator over drying agent to room temperature. 50 g of the dried sample are re- moved and sieved off by means of a sieving machine equipped with an analytical sieve (for example, type: AS 200 control from Retsch GmbH, Hanau) at a swing am- plitude of 1.2 mm for ten minutes through an analytical sieve, the analytical sieve being selected depending on the grain distribution of the sample to be measured (for example, analytical sieve of mesh size: 0.315 mm, diameter: 200 mm, height: 50 mm); the subsize grain is discarded. 5 ml of the nominal grain are filled into a 10 ml graduated cylinder to DIN ISO 384 (volume: 10 ml, height: 90 mm) and the weight is accurately determined to 0.1 mg using an analytical balance (type: BP121S from Sartorius AG, Gottingen, weighing range: 120 g, accuracy class: E2, readability: 0.1 mg) by means of a weighing glass having a ground glass lid (volume: 15 ml, diameter: 35 mm, height: 30 mm). The weighed sample is placed together with a tungsten carbide grinding ball of 20 mm diameter in a 25 ml grinding cup with screw action closure (volume: 25 ml, diameter: 30 mm, length: 65 mm, material of construction: stain- less steel) and then the abrasion test is carried out by means of a swing mill (type: MM301 from Retsch GmbH, Haan, swing mill with grinding cup); the grinding cup swings in a horizontal position for one minute at a frequency of 10 Hz in the swing mill, causing the grinding ball to impact on the sample and thus create abrasion. Subsequently, the sample is sieved off by means of a sieving machine at a swing amplitude of 1.2 mm for five minutes through the aforementioned ana- lytical sieve, the subsize grain again being discarded and the nominal grain, which is dependent on the grain distribution of the relevant sample (e.g. nominal grain greater than 0.315 mm), being weighed back accurately to 0.1 mg in the weighing glass with lid. The abrasion hardness is computed as a mass fraction in % by the following formula: abrasion hardness [%] = (100 x back- weighed weight [g])/original weight [g]. According to this method of determination, modified by the applicant company by modifying the aforementioned CEFIC standard, the abrasion resistance of the high- performance adsorbents of the present invention is at least 75%, particularly at least 80%, preferably at least 85%, more preferably at least 90%, most prefera- bly at least 95%. As stated above, it is a further special feature of the high-performance adsorbents of the present invention that they also have a certain degree of microporosity and thus also a certain micropore surface area (i.e. surface area which is formed by pores having pore di- ameters of ≤ 20 A. In general, the carbon black method micropore surface area of the high-performance adsorb- ents of the present invention which is formed by pores having pore diameters of ≤ 20 A is at least 1000 m2/g, particularly at least 1100 m2/g, preferably at least 1200 m2/g, and is generally in the range from 1000 to 1800 m2/g, particularly 1100 to 1600 m2/g, preferably 1200 to 1500 m2/g. In general, the carbon black method micropore surface area of the high-performance adsorbents of the present invention which is formed by pores having pore diame- ters of ≤ 20 A is at least 30%, particularly at least 40%, preferably at least 50% of the total pore surface area of the high-performance adsorbents of the present invention. More particularly, the carbon black method micropore surface area of the high-performance adsorb- ents of the invention which is formed by pores having pore diameters of ≤ 20 A is in the range from 50 to 90%, particularly 55 to 85%, preferably 60 to 80% of the total pore surface area of the high-performance ad- sorbents of the present invention. Similarly, the weight- and volume-based volume Vads (N2) of the high-performance adsorbents of the present in- vention at different partial pressures p/p0 is very large: The weight-based adsorbed N2 volume VadS(Wt) of the high- performance adsorbents of the present invention, deter- mined at a partial pressure p/po of 0.25, is at least 300 cm3/g, particularly at least 350 cm3/g, preferably at least 375 cm3/g, and is particularly in the range from 300 to 800 cm3/g, preferably 350 to 700 cm3/g, more preferably 375 to 650 cm3/g. In general, the volume-based adsorbed N2 volume Vads(vol) of the high-performance adsorbents of the present in- vention, determined at a partial pressure p/po of 0.25, is at least 75 cm3/cm3, particularly at least 100 cm3/cm3, and is particularly in the range from 75 to 300 cm3/cm3, preferably 80 to 275 cm3/cm3, more prefera- bly 90 to 250 cm3/cm3. In general, the weight-based adsorbed N2 volume VadS(Wt) of the high-performance adsorbents of the present in- vention, determined at a partial pressure p/po of 0.995, is at least 400 cm3/g, particularly at least 450 cm3/g, and is particularly in the range from 400 to 2300 cm3/g, preferably 450 to 2200 cm3/g, more preferably 750 to 2100 cm3/g. In general, the volume-based adsorbed N2 volume VadS(Vol) of the high-performance adsorbents of the present in- vention, determined at a partial pressure p/po of 0.995, is at least 200 cm3/cm3, particularly at least 250 cm3/cm3, and is particularly in the range from 200 to 500 cm3/cm3, preferably 250 to 400 cm3/cm3, more pref- erably 275 to 380 cm3/cm3. The high-performance adsorbents of the present inven- tion are based on granular, in particular spherical, activated carbon whose measure of central tendency par- ticle diameter, determined to ASTM D2862-97/04, is gen- erally in the range from 0.01 to 2.0 mm, particularly 0.01 to 1.0 mm, preferably 0.05 to 0.09 mm, more pref- erably 0.1 to 0.8 mm, most preferably 0.15 to 0.7 mm. The ash content of the high-performance adsorbents of the present invention, determined to ASTM D2866-94/04, is at most 1%, particularly at most 0.8%, preferably at most 0.6%, more preferably at most 0.5%. The ASTM D2867-04/04 moisture content of the high- performance adsorbents of the present invention is at most 1%, particularly at most 0.5%, preferably at most 0.2%. The high-performance adsorbents of the present inven- tion generally have a bulk density, determined to ASTM B527-93/00, in the range from 150 to 750 g/1, particu- larly 175 to 650 g/1, preferably 200 to 600 g/1. In accordance with a particular embodiment of the pre- sent invention, the present invention provides high- performance adsorbents based on activated carbon in the form of discrete grains of activated carbon, preferably in spherical form, particularly as described above, characterized by the following parameters: • a pore volume fraction formed by pores having pore diameters of more than 20 A which comprises at least 55% of the total pore volume of the high- performance adsorbents, • a measure of central tendency pore diameter of more than 25 A. • a BET surface area of at least 1250 m2/g, • a methylene blue value of at least 15 ml, and • a molasses number of at least 300. The present invention further provides - in accordance with a second aspect of the present invention - the present invention process for producing the high- performance adsorbents according to the present inven- tion. In accordance with this aspect of the present in- vention, the present invention accordingly provides a process for producing the above-described high- performance adsorbents based on activated carbon, which process comprises a carbonaceous starting material be- ing initially carbonized and subsequently activated, wherein the activation is carried out in two stages, wherein the carbonized starting material is initially subjected, in a first activating step, to an activation in an atmosphere comprising water vapor, followed by a second activating step of activation in an atmosphere comprising CO2. The high-performance adsorbents of the present inven- tion are produced using carbonaceous starting materi- als, in particular sulfonated styrene-divinylbenzene copolymers, particularly sulfonated divinylbenzene- crosslinked polystyrenes, preferably in grain form, more preferably in spherical form. The divinylbenzene content of the sulfonated styrene-divinylbenzene co- polymers used as starting materials to produce the high-performance adsorbents of the present invention should particularly be in the range from 1 to 20% by weight, particularly 1 to 15% by weight, preferably 2 to 10% by weight, based on the styrene-divinylbenzene copolymers. The starting copolymers can in principle be selected from the gel type or else from the macroporous type. When unsulfonated starting materials are used, the sulfonation can be carried out in situ (in particu- lar before and/or during the carbonization), particu- larly using methods known per se to one skilled in the art, preferably by means of sulfuric acid and/or oleum and/or SO3; this is familiar per se to one skilled in the art (cf. also the prior art described at the begin- ning) . Starting materials which have proven particu- larly advantageous are the gel-form or macroporous types of the corresponding ion exchange resins or of the corresponding unsulfonated precursors of ion ex- change resins which still have to be sulfonated. The carbonization (also known by the synonyms of pyro- lysis, burn-out or smoldering) converts the carbona- ceous starting polymers to carbon; that is, in other words, the carbonaceous starting material is carbon- ized. Carbonization of the aforementioned organic po- lymeric grains, in particular polymeric spherules, based on styrene and divinylbenzene which comprise sul- fonic acid groups leads to the detachment of the sulfo- nic acid groups during the carbonization to free radi- cals and thus to crosslinks without which there would be no pyrolysis residue (= carbon) . In general, the carbonization is carried out under an inert atmosphere (for example nitrogen) or an at most slightly oxidizing atmosphere. It can similarly be advantageous for the inert atmosphere of the carbonization, in particular if it is carried out at comparatively high temperatures (for example in the range from about 500 to 650°C) to be admixed with a minor amount of oxygen, in particular in the form of air (for example 1 to 5%) in order that an oxidation of the carbonized polymeric skeleton may be effected and the subsequent activation may thereby be facilitated. In general, the carbonization is car- ried out at temperatures of 100 to 950°C, particularly 150 to 900°C, preferably 300 to 850°C. The total dura- tion of the carbonization is approximately 30 minutes to approximately 10 hours, particularly approximately 1 hour to approximately 6 hours. Following the carbonization, the carbonized intermedi- ate product is subjected to an activation resulting, at the end of which, in the present invention' s high- performance adsorbents based on activated carbon in grain form, in particular spherical form. The basic principle of the activation is to degrade a portion of the carbon generated during the carbonization, selec- tively and specifically under suitable conditions. This gives rise to numerous pores, fissures and cracks, and the surface area per unit mass increases appreciably. Activation thus involves a specific burn-out of the carbon. Since carbon is degraded in the course of acti- vation, this operation goes hand in hand with a loss of substance which - under optimal conditions - is equiva- lent to an increase in the porosity and in the internal surface area and in the pore volume. Activation is therefore carried out under selective or to be more precise policed oxidizing conditions. The special feature of how the high-performance adsorb- ents of the present invention are produced, as well as the selection of the starting material described above, resides in the specific management of the activation process, in particular in the two-stageness of the ac- tivation process, wherein the carbonized starting mate- rial is initially subjected, in a first activating step, to an activation in an atmosphere comprising wa- ter vapor, followed by a second activating step in an atmosphere comprising CO2. As the studies carried out by the applicant have determined it is surprisingly only the separate performance of these activating steps in the aforementioned order that leads to the desired products. Reversing the order of the activating steps, or one conjointly conducted activating step in a water vapor/carbon dioxide atmosphere leads in contrast to distinctly less performance-capable products which do not have the desired properties, particularly not the high total porosity coupled with high meso-/macropore content and a relatively high absolute micropore volume and also high mechanical stability. As the studies by the applicant company have surprisingly shown when the process is carried out according to the present inven- tion water vapor activation leads predominantly to the formation of the micropore fraction, while carbon diox- ide activation contributes predominantly to formation of the meso- and macropores, and surprisingly the for- mation of the meso- and macropore volume is not at the expense of the micropore volume, or vice versa. What is therefore novel and surprising is in total that this produces a very large total pore volume coupled with very high stability and abrasion resistance and also very high meso- and macropore fraction coupled with si- multaneously high micropore fraction (i.e., the forma- tion of meso- and macropores to the enormous extent in the products of the present invention does not lead to a reduction in the micropore fraction, as customary in the prior art). On the contrary, a high micropore frac- tion is achieved while the meso-/macropore volume frac- tion is also high at the same time. The general procedure is for the first activating step to be carried out at temperatures of 700 to 1300°C, particularly 800 to 1200°C, preferably 850 to 950°C, and/or for a duration of 5 to 24 hours, preferably 5 to 15 hours, particularly 6 to 12 hours. Usually, the du- ration of the first activation stage can be controlled as a function of the attainment of a predetermined io- dine number; for example, the first activation stage can be carried out to attainment of an iodine number of at least 1000 mg/g, particularly at least 1250 mg/g. The atmosphere of the first activation stage comprises water vapor, particularly a mixture of water va- por/inert gas, preferably a mixture of water va- por/nitrogen, or consists thereof. For the aforemen- tioned reasons, the presence of activating gases other than water vapor, particularly the presence of carbon oxides (CO2 for example), oxygen and/or ammonia, must be foreclosed in the context of the first activation stage. Good results are obtained when the throughput or to be more precise the amount used of water vapor is 25 to 350 1/h, particularly 50 to 300 1/h, reckoned as wa- ter (i.e., liquid water at 25°C and under atmospheric pressure). Depending on the amount of starting material to be activated (= carbonisate previously produced by carbonization) , the amount used or the mass-based throughput of water vapor should advantageously be 0.01 to 50 l/(h.kg), particularly 0.02 to 25 l/(h.kg), pref- erably 0.02 to 5 l/(h.kg), reckoned as water (i.e., liquid water at 25°C and under atmospheric pressure) and based on starting material to be activated with wa- ter vapor. The general procedure for the second activating step is for the second activating step to be carried out at temperatures of 700 to 1300°C, particularly 800 to 1200°C, preferably 850 to 950°C, and/or for a duration of 1 to 10 hours, particularly 3 to 8 hours. The atmos- phere of the second activation stage comprises CO2, par- ticularly pure CO2 or a mixture of CO2/inert gas, par- ticularly a mixture of CO2/nitrogen, or consists thereof, and pure carbon dioxide is particularly pre- ferred. For the aforementioned reasons, the presence of activating gases other than CO2, in particular the pres- ence of water vapor, must be foreclosed in the context of the second activation stage. Good results are ob- tained when the throughput or the amount used of CO2 is 10 to 250 m3/h, particularly 20 to 200 m3/h (based on pure CO2) . Depending on the amount of starting material to be activated, the amount used or the mass-based throughput of CO2 should advantageously be 0.001 to 100 m3/(h-kg), particularly 0.01 to 50 m3/(h.kg), pref- erably 0.05 to 10 m3/(h.kg), reckoned as pure gaseous CO2 under activating conditions, particularly at the re- spective pressure and the respective temperature, which are selected for the activation, and based on starting material to be activated with CO2. The process is typically carried out such that the first and second activation stages merge into each other (for example by changing the activating atmos- phere within the same apparatus). What is surprising is in particular that, first, the way the activation is carried out according to the pre- sent invention provides exact control of the porosity with regard to the micro-, meso- and macropore frac- tions and, secondly, that an extremely high abrasion resistance and mechanical compressive strength result despite the high porosity coupled with simultaneously high meso- and macroporosity and also good microporos- ity. It was unforeseeable that this approach selec- tively generates high meso- and macroporosity coupled with simultaneously sufficient microporosity. Porosity can be adjusted or controlled to specific val- ues by varying the previously specified activating con- ditions. The high-performance adsorbents of the present invention can thus be custom tailored so to speak. High-performance adsorbents based on activated carbon which combine high meso- and macroporosity with good microporosity and also high stability and abrasion re- sistance are not known from the prior art. Another wel- come aspect is the excellent adsorption behavior to molecules of virtually any desired molecular size due to the presence of all kinds of pores in relatively large amounts or fractions. Similarly welcome is the excellent impregnatability of the products of the pre- sent invention with catalysts or to be more precise metals or metal salts. The graphs in figure 1 and figure 2 show N2 adsorption isotherms for two different high-performance adsorbents of the present invention, which were produced under different activating conditions. The physical-chemical properties of the two high-performance adsorbents of the present invention are also summarized in Table 1 below. For comparison, a commercially available acti- vated carbon from Kureha is also listed therein with the physical-chemical properties in question. The data reported in Table 1 show the superiority of the high-performance adsorbents of the present inven- tion over a prior art activated carbon: The combination of high total porosity with high meso-/macropore volume fraction at high BET surface area and also good abso- lute microporosity, high mechanical durability and ex- cellent adsorption properties is in this combination - as well as the other physical-chemical parameters - only to be found in the high-performance adsorbents of the present invention. The present invention thus makes it possible to produce high-performance adsorbents based on activated carbon in grain form, in particular spherical form, which are superior to commercially available products. The inventive high-performance adsorbents "activated carbon I" and "activated carbon II" recited in Table 1 are each produced as follows: commercially available dried ion exchanger precursors based on divinylbenzene- crosslinked polystyrene copolymers having a divinyl- benzene content of about 4% are sulfonated in a conven- tional manner at temperatures of 100°C to 150°C using a sulfuric acid/oleum mixture. This is followed in a con- ventional manner by carbonization at temperatures up to 850°C for four hours under nitrogen and subsequently the induction of activation. Inventive activated carbon I was produced by performing the first activation stage ("water vapor activation") for a duration of about 8.5 hours at about 900°C with a water vapor throughput of about 100 m3/h and the second activation stage ("carbon dioxide activation") for a duration of about 8.0 hours at about 900°C with a carbon dioxide throughput of about 35 m3/h; in contrast, inventive activated carbon II was produced by performing the first activation stage ("water vapor activation") for a duration of about 10.5 hours at about 925°C with a water vapor throughput of about 125 m3/h and the second activation stage ("carbon dioxide activation") for a duration of about 8 hours at about 925°C with a carbon dioxide throughput of about 40 m3/h. After cooling down to room temperature, the inventive products recited in Table 1 are obtained. The present invention further provides - in accordance with a third aspect of the present invention - the pre- sent invention use of the high-performance adsorbents according to the present invention. The high-performance adsorbents of the present inven- tion are particularly useful for the adsorption of tox- ins, noxiants and odors, for example from gas or to be more precise air streams. The high-performance adsorb- ents of the present invention are further useful for purifying and cleaning gases, particularly for purify- ing air, and also liquids, such as, in particular, wa- ter (for example drinking water treatment). More par- ticularly, the high-performance adsorbents of the pre- sent invention are useful for impregnation (for example with catalysts or to be more precise metals or metal salts). The high-performance adsorbents of the present inven- tion are also useful for example for or in the food in- dustry, particularly for preparing and/or decolorizing food products. The high-performance adsorbents of the present inven- tion can further be used in adsorptive filtering mate- rials or to be more precise in the manufacture of ad- sorptive filtering materials. Such adsorptive filtering materials are useful in the manufacture of protective apparel in particular, for example protective suits, protective gloves, protective underwear, protective footwear, etc., in particular for the civilian or mili- tary sector (for example NBC protection). The high-performance adsorbents of the present inven- tion are further useful in the sector of medicine or pharmacy, particularly as a medicament or medicament constituent. The high-performance adsorbents of the present inven- tion can finally also be used as sorptive storage media for gases and liquids. Owing to their high total porosity coupled with high meso- and macroporosity and similarly a certain degree of microporosity and also excellent mechanical stabil- ity with excellent adsorptive properties, the high- performance adsorbents of the present invention are distinctly superior to comparable adsorbents of the prior art. Further embodiments, modifications and variations of the present invention are readily discernible and real- izable for those skilled in the art on reading the de- scription without their having to leave the realm of the present invention. We-Claim: 1. High-performance adsorbents based on activated carbon in the form of discrete grains of activated carbon, wherein: • at least 70% of the total pore volume of the high-performance adsorbents are formed by pores having pore diameters of more than 20 Å, • the high-performance adsorbents have a measure of central tendency pore diameter (mean pore di- ameter) of more than 25 Å, • the high-performance adsorbents have a BET sur- face area of at least 1,250 m2/g, and • the high-performance adsorbents have an iodine number of at least 1,250 mg/g. 2. The high-performance adsorbents based on activated carbon as claimed in claim 1, wherein the BET sur- face area of the high-performance adsorbents is in the range from 1,250 m2/g to 2,800 m2/g. 3. The high-performance adsorbents based on activated carbon as claimed in claim 1, wherein the high- performance adsorbents have a butane adsorption in the range from 30 to 80%. 4. The high-performance adsorbents based on activated carbon as claimed in claim 1, wherein the high- performance adsorbents have an iodine number in the range from 1,250 to 2,100 mg/g. 5. The high-performance adsorbents based on activated carbon as claimed in claim 1, wherein the high- performance adsorbents have a methylene blue value in the range from 15 to 60 ml. 6. The high-performance adsorbents based on activated carbon as claimed in claim 1, wherein the high- performance adsorbents have a molasses number in the range from 300 to 1,400. 7. A process for producing the high-performance ad- sorbents based on activated carbon, as claimed in claim 1, which process comprises a carbonaceous starting material being initially carbonized and subsequently activated, wherein the activation is carried out in two stages, wherein the carbonized starting material is initially subjected, in a first activating step, to an activation in an at- mosphere comprising water vapor, followed by a second activating step of activation in an atmos- phere comprising CO2. 8. An adsorptive filtering material comprising the high-performance adsorbents based on activated carbon as claimed in claim 1. 9. A piece of protective apparel comprising the high- performance adsorbents based on activated carbon as claimed in claim 1. The invention concerns high-performance adsorbents based on activated carbon of high meso- and macroporos- ity which are present in the form of discrete grains of activated carbon, wherein • at least 55% of the total pore volume of the high-performance adsorbents are formed by pores (i.e. meso- and macropores) having pore diame- ters of more than 20 Å, • the high-performance adsorbents have a measure of central tendency pore diameter of more than 25 Å, and • the high-performance adsorbents have a BET sur- face area of at least 1250 m2/g. These high-performance adsorbents are obtainable by a novel process comprising specific two-stage activation, and have, in addition to the aforementioned properties, an excellent abrasion and bursting resistance, so that they are useful for a multiplicity of different appli- cations.

Full Text

HIGH-PERFORMANCE ADSORBENTS BASED ON ACTIVATED CARBON
HAVING HIGH MESO- AND MACROPOROSITY
The present invention concerns the adsorption arts.
More particularly, the present invention concerns high-
performance adsorbents based on activated carbon of
high meso- and macroporosity and a process for produc-
tion thereof and also the use of these high-performance
adsorbents, particularly for adsorptive filtering mate-
rials, for the food industry (for example for preparing
and/or decolorizing food products, for the adsorption
of toxins, noxiants and odors, particularly from gas or
air streams, for purifying or cleaning gases, particu-
larly air, and liquids, particularly water, for appli-
cation in medicine or to be more precise pharmacy, and
also as sorptive storage media particularly for gases,
liquids and the like.
Activated carbon has fairly unspecific adsorptive prop-
erties and therefore is the most widely used adsorbent.
Legislation as well as the rising sense of responsibil-
ity for the environment lead to a rising demand for ac-
tivated carbon.
Activated carbon is generally obtained by carbonization
(also referred to by the synonyms of smoldering, pyro-
lysis, burn-out, etc) and subsequent activation of car-
bonaceous compounds, preferably such compounds as lead
to economically reasonable yields. This is because the
weight losses through detachment of volatile constitu-
ents in the course of carbonization and through the
subsequent burn-out in the course of activation are ap-
preciable. For further details concerning the produc-
tion of activated carbon, see for example H.v. Kienle
and E. Bader, Aktivkohle und ihre industrielle An-
wendung, Enke Verlag Stuttgart, 1980.
The constitution of the activated carbon produced -
finely or coarsely porous, firm or brittle, etc - de-

pends on the starting material. Customary starting ma-
terials are coconut shells, charcoal and wood (for ex-
ample wood wastes), peat, bituminous coal, pitches, but
also particular plastics which play a certain part in
the production of woven activated carbon fabrics for
example.
Activated carbon is used in various forms: pulverized
carbon, splint coal carbon, granulocarbon, molded car-
bon and also, since the end of the 1970s, spherical ac-
tivated carbon ("spherocarbon"). Spherical activated
carbon has a number of advantages over other forms of
activated carbon such as pulverized carbon, splint coal
carbon, granulocarbon, molded carbon and the like that
make it useful or even indispensable for certain appli-
cations: it is free flowing, abrasion resistant or to
be more precise dustless, and hard. Spherocarbon is in
great demand for particular applications, for example,
because of its specific form, but also because of its
high abrasion resistance.
Spherocarbon is mostly still being produced today by
multistage and very costly and inconvenient processes.
The best known process consists in producing spherules
from bituminous coal tar pitch and suitable asphaltic
residues from the petrochemical industry, which are
oxidized to render them unmeltable and then smoldered
and activated. For example, spherocarbon can also be
produced in a multistage process proceeding from bitu-
men. These multistage processes are very cost intensive
and the associated high cost of this spherocarbon pre-
vents many applications wherein spherocarbon ought to
be preferable by virtue of its properties.
WO 98/07655 A1 describes a process for producing acti-
vated carbon spherules wherein a mixture comprising a
diisocyanate production distillation residue, a carbo-
naceous processing aid and if appropriate one or more
further additives is processed into free-flowing spher-

ules and subsequently the spherules obtained in this
way are carbonized and then activated.
It is further prior art to produce spherocarbon by
smoldering and subsequent activation of new or used ion
exchangers comprising sulfonic acid groups, or by smol-
dering ion exchanger precursors in the presence of sul-
furic acid and subsequent activation, the sulfonic acid
groups and the sulfuric acid respectively having the
function of a crosslinker. Such processes are described
for example in DE 43 28 219 A1 and DE 43 04 026 A1 and
also in DE 196 00 237 Al including the German patent-
of-addition application DE 196 25 069 A1.
However, there are a number of specific applications
where it is not only the geometry or to be more precise
the external shape of the activated carbon which is of
decisive importance, but also its porosity, in particu-
lar the total pore volume and the adsorption capacity
on the one hand and the distribution of the pores,
i.e., the fraction of micro-, meso- and macropores in
relation to the total pore volume, on the other.
There are a number of applications requiring a particu-
larly high meso- and macroporosity of the activated
carbon, i.e., a high meso- and macropore volume frac-
tion, coupled with an altogether high total pore vol-
ume, for example in relation to the applications men-
tioned at the beginning, for example for use in the
food industry, in the manufacture of certain adsorptive
filtering materials (for example for NBC protective ap-
parel) , for the adsorption of toxins, noxiants and
odors, particularly from gas or air streams, for puri-
fying or cleaning gases, such as in particular air, and
also liquids, for application in medicine or to be more
precise pharmacy, in the sorptive storage of gases or
liquids and the like.
True, the activated carbon known for this purpose from

the prior art does have a certain degree of meso- and
macroporosity, but that degree is not sufficient in all
cases. In addition, increasing porosity is often ob-
served to be accompanied by an unwelcome, occasionally
unacceptable decrease in mechanical stability or to be
more precise abrasion resistance. Nor are the fraction
of the total pore volume which is accounted for by
meso- and macropores and the absolute pore volume al-
ways sufficient to ensure adequate performance capabil-
ity and/or an adequate impregnatability (for example
impregnation with metals or metal salts) for all appli-
cations.
It is therefore an object of the present invention to
provide, on the basis of activated carbon, a high-
performance adsorbent which is suitable for the afore-
mentioned fields of application in particular and which
at least substantially avoids or else at least amelio-
rates the above-described disadvantages of the prior
art. More particularly, the adsorbent to be provided
according to the present invention should have a high
meso- and macroporosity, i.e., a high meso- and macro-
porous fraction in relation to the total pore volume
and also a large total pore volume, yet at the same
time also good mechanical stability, particularly a
high stability to abrasion and bursting.
In the context of the present invention, the term "mi-
cropores" refers to pores having pore diameters of up
to 20 A inclusive, whereas the term "mesopores" refers
to pores having pore diameters in the range of more
than 20 A (i.e., > 20 Å) to 500 Å inclusive and the
term "macropores" refers to pores having pore diameters
of more than 500 Å (i.e., > 500 Å):
• micropores: pore diametermicropores ≥ 20 Å
• mesopores: 20 Å • macropores: pore diametermacropores > 500 Å
By way of a solution to the problem described above,

the present invention proposes - in accordance with a
first aspect of the present invention - high-
performance adsorbents based on activated carbon in the
form of discrete grains of activated carbon, preferably
in spherical form, according to claim 1. Further, in
particular advantageous embodiments of the high-
performance adsorbents of the present invention are
subject matter of the corresponding subclaims.
The present invention further provides - in accordance
with a second aspect of the present invention - the
present invention process for producing the high-
performance adsorbents according to the present inven-
tion, as more particularly defined in the corresponding
process claims.
The present invention yet further provides - in accor-
dance with a third aspect of the present invention -
the present invention use of the high-performance ad-
sorbents according to the present invention, as more
particularly defined in the corresponding use claims.
The present invention accordingly provides - in accor-
dance with a first aspect of the present invention -
high-performance adsorbents based on activated carbon
in the form of discrete grains of activated carbon,
preferably in spherical form, these high-performance
adsorbents being characterized by the following parame-
ters :
• a pore volume fraction formed by pores having pore
diameters of more than 20 A (i.e., in other words, a
meso- and macropore volume fraction) which comprises
at least 55% of the total pore volume of high-
performance adsorbents (This parameter is inter-
changeably also referred to as "fraction of external
pore volume in relation to total pore volume".),
• a measure of central tendency pore diameter of more

than 25 A.
• a BET surface area of at least 1250 m2/g,
The present high-performance adsorbents or to be more
precise activated carbons, in addition to the afore-
mentioned properties or to be more precise parameters,
particularly a high meso- and macropore volume fraction
(i.e., a high pore volume fraction due to pores having
a pore diameter of more than 20 Å), are further notable
in particular for a large total porosity and a simulta-
neously large BET surface area.
As will be shown in what follows, the mechanical
strength, particularly the abrasion resistance and the
bursting or to be more precise compressive strength, of
the present high-performance adsorbents is despite the
high total porosity extremely high - in contrast to
comparable high-porosity activated carbons of the prior
art - so that the present high-performance adsorbents
or to be more precise activated carbons are also suit-
able for applications where they are exposed to large
mechanical loads.
In relation to all the parameter indications here-
inabove and hereinbelow, it is to be noted that the re-
cited limits, in particular upper and lower limits, are
included, i.e., all statements of values are to be un-
derstood as including the respective limits, except
where otherwise stated in an individual case. It will
further be understood that in an individual case or in
relation to an application it may be necessary if ap-
propriate to depart slightly from the limits mentioned
without leaving the realm of the present invention.
The hereinabove and hereinbelow mentioned parameter
data are determined using standardized or explicitly
indicated methods of determination or using methods of
determination familiar per se to one skilled in the

art.
The parameter data concerning the characterization of
the porosity, particularly of the above-specified meso-
and macropore fraction (i.e., the fraction of the total
pore volume of the high-performance adsorbents which is
contributed by pores having pore diameters of more than
20 A) each follow from the nitrogen isotherm of the ac-
tivated carbon measured.
The measure of central tendency pore diameter is simi-
larly determined on the basis of the respective nitro-
gen isotherms.
The BET method of determining the specific surface area
is in principle known as such to one skilled in the
art, so that no further details need be furnished in
this regard. All BET surface area data are based on the
ASTM D6556-04 method of determination. The present in-
vention utilizes the Multipoint BET (MP-BET) method of
determination in a partial pressure range p/po of 0.05
to 0.1.
With regard to further details concerning the determi-
nation of the BET surface area or to be precise con-
cerning the BET method, reference may be made to the
aforementioned ASTM D6556-04 standard and also to Rompp
Chemielexikon, 10th edition, Georg Thieme Verlag,
Stuttgart/New York, headword: "BET-Methode", including
the references cited therein, and to Winnacker-Kuchler
(3rd edition), Volume 7, pages 93 ff, and also to Z.
Anal. Chem. 238, pages 187 to 193 (1968).
As observed above and more particularly specified here-
inbelow, one special feature of the high-performance
adsorbents of the present invention is that they have a
very large total pore volume as determined by the Gur-
vich method, to provide a very large adsorptive capac-
ity in which the meso- and macropore volume fraction

(i.e., that is, the pore volume fraction due to pores
having pore diameters above 20 Å) is high, viz. at
least 55% of the total pore volume.
The Gurvich determination of total pore volume is a
method of measurement/determination known per se in
this field to a person skilled in the art. For further
details concerning the Gurvich determination of total
pore volume reference may be made for example to
L. Gurvich (1915), J. Phys. Chem. Soc. Russ. 47, 805,
and also to S. Lowell et al., Characterization of Po-
rous Solids and Powders: Surface Area Pore Size and
Density, Kluwer Academic Publishers, Article Technology
Series, pages 111 et seq.
The Gurvich total pore volume of the high-performance
adsorbents of the present invention is at least
0.8 cm3/g, particularly at least 1.0 cm3/g, preferably
at least 1.2 cm3/g, and can generally attain values of
up to 2.0 cm3/g, particularly up to 2.5 cm3/g, prefera-
bly up to 3.0 cm3/g, more preferably up to 3.5 cm3/g.
The Gurvich total pore volume of the high-performance
adsorbents of the present invention is generally in the
range from 0.8 to 3.5 cm3/g, particularly 1.0 to
3.5 cm3/g, preferably 1.2 to 3.2 cm3/g.
Owing to their high meso- and macroporosity, the meso-
and macropore volume of the high-performance adsorbents
of the present invention (i.e., that is, in other
words, the pore volume formed by pores having pore di-
ameters of more than 20 Å) is relatively high in that
in general the carbon black method pore volume of the
high-performance adsorbents of the present invention
which is formed by pores having pore diameters of more
than 20 A (i.e., that is, the meso- and macropore vol-
ume) is in the range from 0.4 to 3.3 cm3/g, particularly
0.8 to 3.2 cm3/g, preferably 1.0 to 3.1 cm3/g, more
preferably 1.2 to 3.0 cm3/g, most preferably 1.2 to

2.8 cm3/g. The pore volume formed by pores having pore
diameters of more than 20 Å is interchangeably also re-
ferred to as "external pore volume".
Generally at least 60%, particularly at least 65%,
preferably at least 70%, more preferably at least 75%,
most preferably at least 80% of the total pore volume
of the high-performance adsorbents of the present in-
vention is formed by the pore volume of pores having
pore diameters of more than 20 A (i.e., that is, in
other words, by the meso- and macropore volume).
Generally 55% to 95%, particularly 60% to 95%, prefera-
bly 65% to 90%, more preferably 70 to 85% of the total
pore volume of the high-performance adsorbents of the
present invention is formed by the pore volume of pores
having pore diameters of more than 20 Å. The aforemen-
tioned percentages thus identify that proportion of the
total pore volume of the high-performance adsorbents of
the present invention which is attributable to the
fraction of the so-called external pore volume (i.e.,
the pore volume formed by pores having pore diameters
of more than 20 Å) .
The carbon black method of determination is known per
se to one skilled in the art (as is the corresponding
analysis, including plotting and fixing of the p/p0
range) , so that no further details are needed in this
regard. In addition, for further details of the carbon
black method of determining the pore surface area and
the pore volume reference may be made for example to
R.W. Magee, Evaluation of the External Surface Area of
Carbon Black by Nitrogen Adsorption, Presented at the
Meeting of the Rubber Division of the American Chem.
Soc, October 1994, for example cited in: Quantachrome
Instruments, AUTOSORB-1, AS1 WinVersion 1.50, Operating
Manual, OM, 05061, Quantachrome Instruments 2004, Flor-
ida, USA, pages 71 ff.

Owing to the high meso- and macroporosity of the high-
performance adsorbents of the present invention, the
measure of central tendency pore diameter is relatively
high in that in general it is at least 30 Å, particu-
larly at least 35 Å, preferably at least 40 Å.
In general, the measure of central tendency pore diame-
ter of the high-performance adsorbents of the present
invention is in the range from 25 to 75 Å, particularly
30 to 75 Å, preferably 35 to 70 Å, more preferably 40
to 65 Å.
As stated above, it is a further special feature of the
high-performance adsorbents of the present invention
that BET surface area is relatively large and that it
is at least 1250 m2/g, preferably at least 1400 m2/g,
more preferably at least 1500 m2/g, most preferably at
least 1600 m2/g.
In general, the BET surface area of the high-
performance adsorbents of the present invention is in
the range from 1250 m2/g to 2800 m2/g, particularly 1400
to 2500 m2/g, preferably 1500 to 2300 m2/g, more pref-
erably 1600 to 2100 m2/g.
The carbon black method external pore surface area of
the high-performance adsorbents of the present inven-
tion (i.e., that is, the pore surface area formed by
pores having pore diameters of more than 20 Å) is rela-
tively large, because of the high meso- and macropore
fraction, and is generally in the range from 200 to
1000 m2/g, particularly 250 to 950 m2/g, preferably 350
to 900 m2/g, more preferably 400 to 850 m2/g.
In general, the carbon black method external pore sur-
face area of the high-performance adsorbents of the
present invention (i.e., that is, the pore surface area
formed by pores having pore diameters of more than
20 A) forms up to 30%, particularly up to 40%, prefera-

bly up to 50% of the total pore surface area of the
high-performance adsorbents of the present invention.
More particularly, the carbon black method external
pore surface area of the high-performance adsorbents of
the present invention (i.e., that is, the pore surface
area formed by pores having pore diameters of more than
20 A) forms 10 to 50%, particularly 15 to 45%, prefera-
bly 20 to 40% of the total pore surface area of the
high-performance adsorbents of the present invention.
In addition, the high-performance adsorbents of the
present invention have an extremely high butane adsorp-
tion and simultaneously an extremely high iodine num-
ber, which fact characterizes their property of having
excellent adsorption properties with regard to a wide
variety of materials to be adsorbed.
The ASTM D5742-95/00 butane adsorption of the high-
performance adsorbents of the present invention is gen-
erally at least 30%, particularly at least 35%, pref-
erably at least 40%. In general, the high-performance
adsorbents of the present invention have an ASTM D5742-
95/00 butane adsorption in the range from 30% to 80%,
particularly 35 to 75% preferably 40 to 70%.
The ASTM D4607-94/99 iodine number of the high-
performance adsorbents of the present invention is gen-
erally at least 1250 mg/g, particularly at least
1300 mg/g, preferably at least 1350 mg/g. The high-
performance adsorbents of the present invention pref-
erably have an ASTM D4607-94/99 iodine number in the
range from 1250 to 2100 mg/g, particularly 1300 to
2000 mg/g, preferably 1350 to 1900 mg/g. The iodine
number can be taken as a measure for available surface
area provided by predominantly larger micropores; the
aforementioned values of the iodine number of the high-
performance adsorbents of the present invention show
that the high-performance adsorbents of the present in-
vention simultaneously also have a high microporosity.

Owing to their high meso- and macroporosity, the high-
performance adsorbents of the present invention simi-
larly have high methylene blue and molasses adsorption
numbers which together can be taken as a measure of
available surface area provided predominantly by meso-
and macropores. The methylene blue number or to be more
precise the methylene blue adsorption, which indicates
the amount of methylene blue adsorbed per defined
amount of adsorbents, under defined conditions (i.e.,
the number of ml of a methylene blue standard solution
decolorized by a defined amount of dry and pulverized
adsorbents), relates to larger micropores and predomi-
nantly smaller mesopores and gives an indication of the
adsorptive capacity of the high-performance adsorbents
of the present invention in relation to molecules com-
parable in size to methylene blue. By contrast, the mo-
lasses number must be considered a measure of the meso-
and macroporosity and indicates the amount of adsorb-
ents which is required to decolorize a standard molas-
ses solution, so that the molasses number gives an in-
dication of the adsorptive capacity of the high-
performance adsorbents of the present invention in re-
lation to molecules that are comparable in size to mo-
lasses (generally sugar beet molasses). Together,
therefore, the methylene blue and molasses numbers can
be considered a measure of the meso- and macroporosity
of the high-performance adsorbents of the present in-
vention.
The methylene blue value of the high-performance ad-
sorbents of the present invention which is determined
by following the method of CEFIC (Conseil Europeen des
Federations des Industries Chimiques, Avenue Louise
250, Bte 71, B - 1050 Brussels, November 1986, European
Council of Chemical Manufacturers' Federations, Test
Methods for Activated Carbons, Item 2.4 "Methylene blue
value", pages 27/28) is at least 15 ml, particularly at
least 17 ml, preferably at least 19 ml, and is gener-

ally in the range from 15 to 60 ml, particularly 17 to
50 ml, preferably 19 to 45 ml.
The methylene blue value according to the afore-
mentioned CEFIC method is thus defined as the number of
ml of a methylene blue standard solution which are de-
colorized by 0.1 g of dry and pulverized activated car-
bon. Performing this method requires a glass vessel
with ground stopper, a filter and also a methylene blue
standard solution prepared as follows: 1200 mg of pure
methylene blue dye (corresponding to about 1.5 g of
methylene blue to DAB VI [German Pharmacopeia,
6th edition] or equivalent product) are dissolved in
water in a 1000 ml volumetric flask, and the solution
is allowed to stand for several hours or overnight; to
check its strength, 5.0 ml of the solution are diluted
with 0.25% (volume fractions) acetic acid to 1.0 1 in a
volumetric flask and thereafter the absorbance is meas-
ured at 620 nm and 1 cm path length, and it has to be
0.840 ± 0.010. If the absorbance is higher, it has to
be diluted with the computed amount of water; if it is
lower, the solution is discarded and made up fresh. By
way of sample preparation, the high-performance adsorb-
ents in the form of granular activated carbon are pul-
verized ( at 150°C. Precisely 0.1 g of the spherocarbon is then
combined with 25 ml (5 ml) of the methylene blue stan-
dard solution in a ground glass flask (A preliminary
test has to be carried out to see whether an initial
addition of 25 ml of methylene blue standard solution
with 5 ml additions or an initial addition of 5 ml of
methylene blue standard solution with 1 ml additions
can be used.). The flask is shaken until decolorization
occurs. Then, a further 5 ml (1 ml) of the methylene
blue standard solution are added, and the flask is
shaken to the point of decolorization. The addition of
methylene blue standard solution is repeated in 5 ml
amounts (1 ml amounts) as long as decolorization still
occurs within 5 minutes. The entire volume of the test

solution decolorized by the sample is recorded. The
test is repeated to confirm the results obtained. The
volume of the methylene blue standard solution in ml
which are just decolorized is the methylene blue value
of the high-performance adsorbents. It is to be noted
in this connection that the methylene blue dye must not
be dried, since it is heat sensitive; rather, the water
content must be corrected for purely arithmetically.
The dimensionless molasses number can in principle be
determined either by following the Norit method (Norit
N.V., Amersfoort, Netherlands, Norit Standard Method
NSTM 2.19 "Molasses Number (Europe)") or alternatively
by following the PACS method (PACS = Professional Ana-
lytical and Consulting Services Inc., Coraopolis Penn-
sylvania, USA) . In the context of the present inven-
tion, the values of the molasses number are determined
by following the PACS method. Thus, the PACS method mo-
lasses number of the high-performance adsorbents of the
present invention is at least 300, particularly at
least 350, preferably at least 400, and is generally in
the range from 300 to 1400, particularly 350 to 1300,
preferably 400 to 1250, most preferably 700 to 1200.
Whether by following the Norit method or by following
the PACS method, the molasses number is determined by
determining the amount of pulverized high-performance
adsorbents based on activated carbon that is needed to
decolorize a standard molasses solution. Determination
is effected photometrically, and the standard molasses
solution is standardized against a standardized acti-
vated carbon having a molasses number of 245 and/or
350. For further details in this regard, reference can
be made to the two aforementioned prescriptive methods.
Despite their high porosity, particularly meso- and
macroporosity, the high-performance adsorbents of the
present invention have a high compressive or bursting
strength (resistance to weight loading) and also an ex-

tremely high abrasion resistance.
The compressive or bursting strength (resistance to
weight loading) per grain of activated carbon, in par-
ticular per spherule of activated carbon, is thus at
least 5 newtons, in particular at least 10 newtons and
preferably at least 15 newtons. In general, the com-
pressive or bursting strength (resistance to weight
loading) per grain of activated carbon, particularly
per spherule of activated carbon, ranges from 5 to
50 newtons, in particular from 10 to 45 newtons and
preferably from 15 to 40 newtons.
As mentioned, the abrasion hardness of the high-
performance adsorbents of the present invention is also
extremely high in that the abrasion resistance when
measured by the method of CEFIC (Conseil Europeen des
Federations des Industries Chimigues, Avenue Louise
250, Bte 71, B - 1050 Brussels, November 1986, European
Council of Chemical Manufacturers' Federations, Test
Methods for Activated Carbons, Item 1.6 "Mechanical
Hardness", pages 18/19) is always 100% or virtually
100%. Similarly, when measured according to ASTM D3802
abrasion resistances of the high-performance adsorbents
of the present invention of 100% or virtually 100% are
always obtained.
Therefore, the applicant company has developed a modi-
fied test method on the lines of this CEFIC method in
order that more meaningful values may be obtained. The
modified method of determination provides a better
simulation of the resistance of the sample or to be
more precise of the high-performance adsorbents to
abrasion or attrition under near actual service condi-
tions. For this purpose, the sample is exposed to stan-
dardized conditions for a defined time in a horizon-
tally swinging grinding cup charged with a tungsten
carbide ball. The procedure adopted for this purpose is
as follows: 200 g of a sample are dried for one hour at

(120 ± 2) °C in a circulating air drying cabinet (type:
Heraeus UT 6060 from Kendro GmbH, Hanau) and are subse-
quently cooled down in a desiccator over drying agent
to room temperature. 50 g of the dried sample are re-
moved and sieved off by means of a sieving machine
equipped with an analytical sieve (for example, type:
AS 200 control from Retsch GmbH, Hanau) at a swing am-
plitude of 1.2 mm for ten minutes through an analytical
sieve, the analytical sieve being selected depending on
the grain distribution of the sample to be measured
(for example, analytical sieve of mesh size: 0.315 mm,
diameter: 200 mm, height: 50 mm); the subsize grain is
discarded. 5 ml of the nominal grain are filled into a
10 ml graduated cylinder to DIN ISO 384 (volume: 10 ml,
height: 90 mm) and the weight is accurately determined
to 0.1 mg using an analytical balance (type: BP121S
from Sartorius AG, Gottingen, weighing range: 120 g,
accuracy class: E2, readability: 0.1 mg) by means of a
weighing glass having a ground glass lid (volume:
15 ml, diameter: 35 mm, height: 30 mm). The weighed
sample is placed together with a tungsten carbide
grinding ball of 20 mm diameter in a 25 ml grinding cup
with screw action closure (volume: 25 ml, diameter:
30 mm, length: 65 mm, material of construction: stain-
less steel) and then the abrasion test is carried out
by means of a swing mill (type: MM301 from Retsch GmbH,
Haan, swing mill with grinding cup); the grinding cup
swings in a horizontal position for one minute at a
frequency of 10 Hz in the swing mill, causing the
grinding ball to impact on the sample and thus create
abrasion. Subsequently, the sample is sieved off by
means of a sieving machine at a swing amplitude of
1.2 mm for five minutes through the aforementioned ana-
lytical sieve, the subsize grain again being discarded
and the nominal grain, which is dependent on the grain
distribution of the relevant sample (e.g. nominal grain
greater than 0.315 mm), being weighed back accurately
to 0.1 mg in the weighing glass with lid. The abrasion
hardness is computed as a mass fraction in % by the

following formula: abrasion hardness [%] = (100 x back-
weighed weight [g])/original weight [g].
According to this method of determination, modified by
the applicant company by modifying the aforementioned
CEFIC standard, the abrasion resistance of the high-
performance adsorbents of the present invention is at
least 75%, particularly at least 80%, preferably at
least 85%, more preferably at least 90%, most prefera-
bly at least 95%.
As stated above, it is a further special feature of the
high-performance adsorbents of the present invention
that they also have a certain degree of microporosity
and thus also a certain micropore surface area (i.e.
surface area which is formed by pores having pore di-
ameters of ≤ 20 A. In general, the carbon black method
micropore surface area of the high-performance adsorb-
ents of the present invention which is formed by pores
having pore diameters of ≤ 20 A is at least 1000 m2/g,
particularly at least 1100 m2/g, preferably at least
1200 m2/g, and is generally in the range from 1000 to
1800 m2/g, particularly 1100 to 1600 m2/g, preferably
1200 to 1500 m2/g.
In general, the carbon black method micropore surface
area of the high-performance adsorbents of the present
invention which is formed by pores having pore diame-
ters of ≤ 20 A is at least 30%, particularly at least
40%, preferably at least 50% of the total pore surface
area of the high-performance adsorbents of the present
invention. More particularly, the carbon black method
micropore surface area of the high-performance adsorb-
ents of the invention which is formed by pores having
pore diameters of ≤ 20 A is in the range from 50 to
90%, particularly 55 to 85%, preferably 60 to 80% of
the total pore surface area of the high-performance ad-
sorbents of the present invention.

Similarly, the weight- and volume-based volume Vads (N2)
of the high-performance adsorbents of the present in-
vention at different partial pressures p/p0 is very
large:
The weight-based adsorbed N2 volume VadS(Wt) of the high-
performance adsorbents of the present invention, deter-
mined at a partial pressure p/po of 0.25, is at least
300 cm3/g, particularly at least 350 cm3/g, preferably
at least 375 cm3/g, and is particularly in the range
from 300 to 800 cm3/g, preferably 350 to 700 cm3/g, more
preferably 375 to 650 cm3/g.
In general, the volume-based adsorbed N2 volume Vads(vol)
of the high-performance adsorbents of the present in-
vention, determined at a partial pressure p/po of 0.25,
is at least 75 cm3/cm3, particularly at least
100 cm3/cm3, and is particularly in the range from 75 to
300 cm3/cm3, preferably 80 to 275 cm3/cm3, more prefera-
bly 90 to 250 cm3/cm3.
In general, the weight-based adsorbed N2 volume VadS(Wt)
of the high-performance adsorbents of the present in-
vention, determined at a partial pressure p/po of 0.995,
is at least 400 cm3/g, particularly at least 450 cm3/g,
and is particularly in the range from 400 to 2300 cm3/g,
preferably 450 to 2200 cm3/g, more preferably 750 to
2100 cm3/g.
In general, the volume-based adsorbed N2 volume VadS(Vol)
of the high-performance adsorbents of the present in-
vention, determined at a partial pressure p/po of 0.995,
is at least 200 cm3/cm3, particularly at least
250 cm3/cm3, and is particularly in the range from 200
to 500 cm3/cm3, preferably 250 to 400 cm3/cm3, more pref-
erably 275 to 380 cm3/cm3.
The high-performance adsorbents of the present inven-
tion are based on granular, in particular spherical,

activated carbon whose measure of central tendency par-
ticle diameter, determined to ASTM D2862-97/04, is gen-
erally in the range from 0.01 to 2.0 mm, particularly
0.01 to 1.0 mm, preferably 0.05 to 0.09 mm, more pref-
erably 0.1 to 0.8 mm, most preferably 0.15 to 0.7 mm.
The ash content of the high-performance adsorbents of
the present invention, determined to ASTM D2866-94/04,
is at most 1%, particularly at most 0.8%, preferably at
most 0.6%, more preferably at most 0.5%.
The ASTM D2867-04/04 moisture content of the high-
performance adsorbents of the present invention is at
most 1%, particularly at most 0.5%, preferably at most
0.2%.
The high-performance adsorbents of the present inven-
tion generally have a bulk density, determined to ASTM
B527-93/00, in the range from 150 to 750 g/1, particu-
larly 175 to 650 g/1, preferably 200 to 600 g/1.
In accordance with a particular embodiment of the pre-
sent invention, the present invention provides high-
performance adsorbents based on activated carbon in the
form of discrete grains of activated carbon, preferably
in spherical form, particularly as described above,
characterized by the following parameters:
• a pore volume fraction formed by pores having pore
diameters of more than 20 A which comprises at
least 55% of the total pore volume of the high-
performance adsorbents,
• a measure of central tendency pore diameter of
more than 25 A.
• a BET surface area of at least 1250 m2/g,
• a methylene blue value of at least 15 ml, and

• a molasses number of at least 300.
The present invention further provides - in accordance
with a second aspect of the present invention - the
present invention process for producing the high-
performance adsorbents according to the present inven-
tion. In accordance with this aspect of the present in-
vention, the present invention accordingly provides a
process for producing the above-described high-
performance adsorbents based on activated carbon, which
process comprises a carbonaceous starting material be-
ing initially carbonized and subsequently activated,
wherein the activation is carried out in two stages,
wherein the carbonized starting material is initially
subjected, in a first activating step, to an activation
in an atmosphere comprising water vapor, followed by a
second activating step of activation in an atmosphere
comprising CO2.
The high-performance adsorbents of the present inven-
tion are produced using carbonaceous starting materi-
als, in particular sulfonated styrene-divinylbenzene
copolymers, particularly sulfonated divinylbenzene-
crosslinked polystyrenes, preferably in grain form,
more preferably in spherical form. The divinylbenzene
content of the sulfonated styrene-divinylbenzene co-
polymers used as starting materials to produce the
high-performance adsorbents of the present invention
should particularly be in the range from 1 to 20% by
weight, particularly 1 to 15% by weight, preferably 2
to 10% by weight, based on the styrene-divinylbenzene
copolymers. The starting copolymers can in principle be
selected from the gel type or else from the macroporous
type. When unsulfonated starting materials are used,
the sulfonation can be carried out in situ (in particu-
lar before and/or during the carbonization), particu-
larly using methods known per se to one skilled in the
art, preferably by means of sulfuric acid and/or oleum

and/or SO3; this is familiar per se to one skilled in
the art (cf. also the prior art described at the begin-
ning) . Starting materials which have proven particu-
larly advantageous are the gel-form or macroporous
types of the corresponding ion exchange resins or of
the corresponding unsulfonated precursors of ion ex-
change resins which still have to be sulfonated.
The carbonization (also known by the synonyms of pyro-
lysis, burn-out or smoldering) converts the carbona-
ceous starting polymers to carbon; that is, in other
words, the carbonaceous starting material is carbon-
ized. Carbonization of the aforementioned organic po-
lymeric grains, in particular polymeric spherules,
based on styrene and divinylbenzene which comprise sul-
fonic acid groups leads to the detachment of the sulfo-
nic acid groups during the carbonization to free radi-
cals and thus to crosslinks without which there would
be no pyrolysis residue (= carbon) . In general, the
carbonization is carried out under an inert atmosphere
(for example nitrogen) or an at most slightly oxidizing
atmosphere. It can similarly be advantageous for the
inert atmosphere of the carbonization, in particular if
it is carried out at comparatively high temperatures
(for example in the range from about 500 to 650°C) to
be admixed with a minor amount of oxygen, in particular
in the form of air (for example 1 to 5%) in order that
an oxidation of the carbonized polymeric skeleton may
be effected and the subsequent activation may thereby
be facilitated. In general, the carbonization is car-
ried out at temperatures of 100 to 950°C, particularly
150 to 900°C, preferably 300 to 850°C. The total dura-
tion of the carbonization is approximately 30 minutes
to approximately 10 hours, particularly approximately 1
hour to approximately 6 hours.
Following the carbonization, the carbonized intermedi-
ate product is subjected to an activation resulting, at
the end of which, in the present invention' s high-

performance adsorbents based on activated carbon in
grain form, in particular spherical form. The basic
principle of the activation is to degrade a portion of
the carbon generated during the carbonization, selec-
tively and specifically under suitable conditions. This
gives rise to numerous pores, fissures and cracks, and
the surface area per unit mass increases appreciably.
Activation thus involves a specific burn-out of the
carbon. Since carbon is degraded in the course of acti-
vation, this operation goes hand in hand with a loss of
substance which - under optimal conditions - is equiva-
lent to an increase in the porosity and in the internal
surface area and in the pore volume. Activation is
therefore carried out under selective or to be more
precise policed oxidizing conditions.
The special feature of how the high-performance adsorb-
ents of the present invention are produced, as well as
the selection of the starting material described above,
resides in the specific management of the activation
process, in particular in the two-stageness of the ac-
tivation process, wherein the carbonized starting mate-
rial is initially subjected, in a first activating
step, to an activation in an atmosphere comprising wa-
ter vapor, followed by a second activating step in an
atmosphere comprising CO2. As the studies carried out by
the applicant have determined it is surprisingly only
the separate performance of these activating steps in
the aforementioned order that leads to the desired
products. Reversing the order of the activating steps,
or one conjointly conducted activating step in a water
vapor/carbon dioxide atmosphere leads in contrast to
distinctly less performance-capable products which do
not have the desired properties, particularly not the
high total porosity coupled with high meso-/macropore
content and a relatively high absolute micropore volume
and also high mechanical stability. As the studies by
the applicant company have surprisingly shown when the
process is carried out according to the present inven-

tion water vapor activation leads predominantly to the
formation of the micropore fraction, while carbon diox-
ide activation contributes predominantly to formation
of the meso- and macropores, and surprisingly the for-
mation of the meso- and macropore volume is not at the
expense of the micropore volume, or vice versa. What is
therefore novel and surprising is in total that this
produces a very large total pore volume coupled with
very high stability and abrasion resistance and also
very high meso- and macropore fraction coupled with si-
multaneously high micropore fraction (i.e., the forma-
tion of meso- and macropores to the enormous extent in
the products of the present invention does not lead to
a reduction in the micropore fraction, as customary in
the prior art). On the contrary, a high micropore frac-
tion is achieved while the meso-/macropore volume frac-
tion is also high at the same time.
The general procedure is for the first activating step
to be carried out at temperatures of 700 to 1300°C,
particularly 800 to 1200°C, preferably 850 to 950°C,
and/or for a duration of 5 to 24 hours, preferably 5 to
15 hours, particularly 6 to 12 hours. Usually, the du-
ration of the first activation stage can be controlled
as a function of the attainment of a predetermined io-
dine number; for example, the first activation stage
can be carried out to attainment of an iodine number of
at least 1000 mg/g, particularly at least 1250 mg/g.
The atmosphere of the first activation stage comprises
water vapor, particularly a mixture of water va-
por/inert gas, preferably a mixture of water va-
por/nitrogen, or consists thereof. For the aforemen-
tioned reasons, the presence of activating gases other
than water vapor, particularly the presence of carbon
oxides (CO2 for example), oxygen and/or ammonia, must be
foreclosed in the context of the first activation
stage. Good results are obtained when the throughput or
to be more precise the amount used of water vapor is 25
to 350 1/h, particularly 50 to 300 1/h, reckoned as wa-

ter (i.e., liquid water at 25°C and under atmospheric
pressure). Depending on the amount of starting material
to be activated (= carbonisate previously produced by
carbonization) , the amount used or the mass-based
throughput of water vapor should advantageously be 0.01
to 50 l/(h.kg), particularly 0.02 to 25 l/(h.kg), pref-
erably 0.02 to 5 l/(h.kg), reckoned as water (i.e.,
liquid water at 25°C and under atmospheric pressure)
and based on starting material to be activated with wa-
ter vapor.
The general procedure for the second activating step is
for the second activating step to be carried out at
temperatures of 700 to 1300°C, particularly 800 to
1200°C, preferably 850 to 950°C, and/or for a duration
of 1 to 10 hours, particularly 3 to 8 hours. The atmos-
phere of the second activation stage comprises CO2, par-
ticularly pure CO2 or a mixture of CO2/inert gas, par-
ticularly a mixture of CO2/nitrogen, or consists
thereof, and pure carbon dioxide is particularly pre-
ferred. For the aforementioned reasons, the presence of
activating gases other than CO2, in particular the pres-
ence of water vapor, must be foreclosed in the context
of the second activation stage. Good results are ob-
tained when the throughput or the amount used of CO2 is
10 to 250 m3/h, particularly 20 to 200 m3/h (based on
pure CO2) . Depending on the amount of starting material
to be activated, the amount used or the mass-based
throughput of CO2 should advantageously be 0.001 to
100 m3/(h-kg), particularly 0.01 to 50 m3/(h.kg), pref-
erably 0.05 to 10 m3/(h.kg), reckoned as pure gaseous
CO2 under activating conditions, particularly at the re-
spective pressure and the respective temperature, which
are selected for the activation, and based on starting
material to be activated with CO2.
The process is typically carried out such that the
first and second activation stages merge into each
other (for example by changing the activating atmos-

phere within the same apparatus).
What is surprising is in particular that, first, the
way the activation is carried out according to the pre-
sent invention provides exact control of the porosity
with regard to the micro-, meso- and macropore frac-
tions and, secondly, that an extremely high abrasion
resistance and mechanical compressive strength result
despite the high porosity coupled with simultaneously
high meso- and macroporosity and also good microporos-
ity. It was unforeseeable that this approach selec-
tively generates high meso- and macroporosity coupled
with simultaneously sufficient microporosity.
Porosity can be adjusted or controlled to specific val-
ues by varying the previously specified activating con-
ditions. The high-performance adsorbents of the present
invention can thus be custom tailored so to speak.
High-performance adsorbents based on activated carbon
which combine high meso- and macroporosity with good
microporosity and also high stability and abrasion re-
sistance are not known from the prior art. Another wel-
come aspect is the excellent adsorption behavior to
molecules of virtually any desired molecular size due
to the presence of all kinds of pores in relatively
large amounts or fractions. Similarly welcome is the
excellent impregnatability of the products of the pre-
sent invention with catalysts or to be more precise
metals or metal salts.
The graphs in figure 1 and figure 2 show N2 adsorption
isotherms for two different high-performance adsorbents
of the present invention, which were produced under
different activating conditions. The physical-chemical
properties of the two high-performance adsorbents of
the present invention are also summarized in Table 1
below. For comparison, a commercially available acti-
vated carbon from Kureha is also listed therein with
the physical-chemical properties in question.

The data reported in Table 1 show the superiority of
the high-performance adsorbents of the present inven-
tion over a prior art activated carbon: The combination
of high total porosity with high meso-/macropore volume
fraction at high BET surface area and also good abso-
lute microporosity, high mechanical durability and ex-
cellent adsorption properties is in this combination -
as well as the other physical-chemical parameters -
only to be found in the high-performance adsorbents of
the present invention. The present invention thus makes
it possible to produce high-performance adsorbents
based on activated carbon in grain form, in particular
spherical form, which are superior to commercially
available products.
The inventive high-performance adsorbents "activated
carbon I" and "activated carbon II" recited in Table 1
are each produced as follows: commercially available
dried ion exchanger precursors based on divinylbenzene-
crosslinked polystyrene copolymers having a divinyl-
benzene content of about 4% are sulfonated in a conven-
tional manner at temperatures of 100°C to 150°C using a
sulfuric acid/oleum mixture. This is followed in a con-
ventional manner by carbonization at temperatures up to
850°C for four hours under nitrogen and subsequently
the induction of activation. Inventive activated carbon
I was produced by performing the first activation stage
("water vapor activation") for a duration of about 8.5
hours at about 900°C with a water vapor throughput of
about 100 m3/h and the second activation stage ("carbon
dioxide activation") for a duration of about 8.0 hours
at about 900°C with a carbon dioxide throughput of
about 35 m3/h; in contrast, inventive activated carbon
II was produced by performing the first activation
stage ("water vapor activation") for a duration of
about 10.5 hours at about 925°C with a water vapor
throughput of about 125 m3/h and the second activation
stage ("carbon dioxide activation") for a duration of

about 8 hours at about 925°C with a carbon dioxide
throughput of about 40 m3/h. After cooling down to room
temperature, the inventive products recited in Table 1
are obtained.
The present invention further provides - in accordance
with a third aspect of the present invention - the pre-
sent invention use of the high-performance adsorbents
according to the present invention.
The high-performance adsorbents of the present inven-
tion are particularly useful for the adsorption of tox-
ins, noxiants and odors, for example from gas or to be
more precise air streams. The high-performance adsorb-
ents of the present invention are further useful for
purifying and cleaning gases, particularly for purify-
ing air, and also liquids, such as, in particular, wa-
ter (for example drinking water treatment). More par-
ticularly, the high-performance adsorbents of the pre-
sent invention are useful for impregnation (for example
with catalysts or to be more precise metals or metal
salts).
The high-performance adsorbents of the present inven-
tion are also useful for example for or in the food in-
dustry, particularly for preparing and/or decolorizing
food products.
The high-performance adsorbents of the present inven-
tion can further be used in adsorptive filtering mate-
rials or to be more precise in the manufacture of ad-
sorptive filtering materials. Such adsorptive filtering
materials are useful in the manufacture of protective
apparel in particular, for example protective suits,
protective gloves, protective underwear, protective
footwear, etc., in particular for the civilian or mili-
tary sector (for example NBC protection).
The high-performance adsorbents of the present inven-

tion are further useful in the sector of medicine or
pharmacy, particularly as a medicament or medicament
constituent.
The high-performance adsorbents of the present inven-
tion can finally also be used as sorptive storage media
for gases and liquids.
Owing to their high total porosity coupled with high
meso- and macroporosity and similarly a certain degree
of microporosity and also excellent mechanical stabil-
ity with excellent adsorptive properties, the high-
performance adsorbents of the present invention are
distinctly superior to comparable adsorbents of the
prior art.
Further embodiments, modifications and variations of
the present invention are readily discernible and real-
izable for those skilled in the art on reading the de-
scription without their having to leave the realm of
the present invention.

We-Claim:

1. High-performance adsorbents based on activated
carbon in the form of discrete grains of activated
carbon, wherein:
• at least 70% of the total pore volume of the
high-performance adsorbents are formed by pores
having pore diameters of more than 20 Å,
• the high-performance adsorbents have a measure
of central tendency pore diameter (mean pore di-
ameter) of more than 25 Å,
• the high-performance adsorbents have a BET sur-
face area of at least 1,250 m2/g, and
• the high-performance adsorbents have an iodine
number of at least 1,250 mg/g.

2. The high-performance adsorbents based on activated
carbon as claimed in claim 1, wherein the BET sur-
face area of the high-performance adsorbents is in
the range from 1,250 m2/g to 2,800 m2/g.
3. The high-performance adsorbents based on activated
carbon as claimed in claim 1, wherein the high-
performance adsorbents have a butane adsorption in
the range from 30 to 80%.
4. The high-performance adsorbents based on activated
carbon as claimed in claim 1, wherein the high-
performance adsorbents have an iodine number in
the range from 1,250 to 2,100 mg/g.

5. The high-performance adsorbents based on activated
carbon as claimed in claim 1, wherein the high-
performance adsorbents have a methylene blue value
in the range from 15 to 60 ml.
6. The high-performance adsorbents based on activated
carbon as claimed in claim 1, wherein the high-
performance adsorbents have a molasses number in
the range from 300 to 1,400.
7. A process for producing the high-performance ad-
sorbents based on activated carbon, as claimed in
claim 1, which process comprises a carbonaceous
starting material being initially carbonized and
subsequently activated, wherein the activation is
carried out in two stages, wherein the carbonized
starting material is initially subjected, in a
first activating step, to an activation in an at-
mosphere comprising water vapor, followed by a
second activating step of activation in an atmos-
phere comprising CO2.
8. An adsorptive filtering material comprising the
high-performance adsorbents based on activated
carbon as claimed in claim 1.
9. A piece of protective apparel comprising the high-
performance adsorbents based on activated carbon
as claimed in claim 1.

The invention concerns high-performance adsorbents
based on activated carbon of high meso- and macroporos-
ity which are present in the form of discrete grains of
activated carbon, wherein
• at least 55% of the total pore volume of the
high-performance adsorbents are formed by pores
(i.e. meso- and macropores) having pore diame-
ters of more than 20 Å,
• the high-performance adsorbents have a measure
of central tendency pore diameter of more than
25 Å, and
• the high-performance adsorbents have a BET sur-
face area of at least 1250 m2/g.
These high-performance adsorbents are obtainable by a
novel process comprising specific two-stage activation,
and have, in addition to the aforementioned properties,
an excellent abrasion and bursting resistance, so that
they are useful for a multiplicity of different appli-
cations.

HIGH-PERFORMANCE ADSORBENTS BASED ON ACTIVATED CARBON AND A PROCESS FOR PRODUCING THE SAME

Documents:

Inventors:

PCT Conventions: