High-performance adsorbents based on activated carbon having high meso- and macropososity

Abstract

The invention concerns high-performance adsorbents based on activated carbon of high meso- and macroporosity 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 diameters 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 surface area of at least 1250 m 2 /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 applications.

1 . High-performance adsorbents based on activated carbon in the form of discrete grains of activated carbon, preferably in spherical form,
 characterized in that
 at least 55% 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 of more than 25 Å, and 
 the high-performance adsorbents have a BET surface area of at least 1250 m 2 /g. 
   
     
     
         2 . The high-performance adsorbents based on activated carbon as claimed in  claim 1 , characterized in that the Gurvich total pore volume of the high-performance adsorbents is at least 0.8 cm 3 /g, particularly at least 1.0 cm 3 /g, preferably at least 1.2 cm 3 /g, and/or in that the Gurvich total pore volume of the high-performance adsorbents reaches values of up to 2.0 cm 3 /g, particularly up to 2.5 cm 3 /g, preferably up to 3.0 cm 3 /g, more preferably up to 3.5 cm 3 /g. 
     
     
         3 . The high-performance adsorbents based on activated carbon as claimed in  claim 1  and/or  2 , characterized in that the Gurvich total pore volume of the high-performance adsorbents is in the range from 0.8 to 3.5 cm 3 /g, particularly 1.0 to 3.5 cm 3 /g, preferably 1.2 to 3.2 cm 3 /g. 
     
     
         4 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the carbon black method pore volume of the high-performance adsorbents which is formed by pores having pore diameters of more than 20 Å is in the range from 0.4 to 3.3 cm 3 /g, particularly 0.8 to 3.2 cm 3 /g, preferably 1.0 to 3.1 cm 3 /g, more preferably 1.2 to 3.0 cm 3 /g, most preferably 1.2 to 2.8 cm 3 /g. 
     
     
         5 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that 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 is formed by the pore volume of pores having pore diameters of more than 20 Å. 
     
     
         6 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that 55% to 95%, particularly 60% to 95%, preferably 65% to 90%, more preferably 70 to 85% of the total pore volume of the high-performance adsorbents is formed by the pore volume of pores having pore diameters of more than 20 Å. 
     
     
         7 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the measure of central tendency pore diameter of the high-performance adsorbents is at least 30 Å, particularly at least 35 Å, preferably at least 40 Å, and/or in that the measure of central tendency pore diameter of the high-performance adsorbents 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. 
     
     
         8 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the BET surface area of the high-performance adsorbents is in the range from 1250 m 2 /g to 2800 m 2 /g, particularly 1400 to 2500 m 2 /g, preferably 1500 to 2300 m 2 /g, more preferably 1600 to 2100 m 2 /g. 
     
     
         9 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the carbon black method pore surface area formed by pores having pore diameters of more than 20 Å is in the range from 200 to 1000 m 2 /g, particularly 250 to 950 m 2 /g, preferably 350 to 900 m 2 /g, more preferably 400 to 850 m 2 /g. 
     
     
         10 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the carbon black method pore surface area formed by pores having pore diameters of more than 20 Å comprises up to 30%, particularly up to 40%, preferably up to 50% of the total pore surface area of the high-performance adsorbents, and/or in that the carbon black method pore surface area formed by pores having pore diameters of more than 20 Å comprises 10 to 50%, particularly 15 to 45%, preferably 20 to 40% of the total pore surface area of the high-performance adsorbents. 
     
     
         11 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the high-performance adsorbents have a butane adsorption of at least 30%, particularly at least 35%, preferably at least 40%, and/or in that the high-performance adsorbents have a butane adsorption in the range from 30 to 80%, particularly 35 to 75%, preferably 40 to 70%. 
     
     
         12 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the high-performance adsorbents have an iodine number of at least 1250 mg/g, particularly at least 1300 mg/g, preferably at least 1350 mg/g, and/or in that the high-performance adsorbents have an iodine number in the range from 1250 to 2100 mg/g, particularly 1300 to 2000 mg/g, preferably 1350 to 1900 mg/g. 
     
     
         13 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the high-performance adsorbents have a methylene blue value of at least 15 ml, particularly at least 17 ml, preferably at least 19 ml, and/or in that the high-performance adsorbents have a methylene blue value in the range from 15 to 60 ml, particularly 17 to 50 ml, preferably 19 to 45 ml. 
     
     
         14 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the high-performance adsorbents have a molasses number of at least 300, particularly at least 350, preferably at least 400, and/or in that the high-performance adsorbents have a molasses number in the range from 300 to 1400, particularly 350 to 1300, preferably 400 to 1250, most preferably 700 to 1200. 
     
     
         15 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized by a compressive or bursting strength per grain of activated carbon, particularly per spherule of activated carbon, of at least 5 newtons, particularly at least 10 newtons, preferably at least 15 newtons, and/or characterized by a compressive or bursting strength per grain of activated carbon, particularly per spherule of activated carbon, in the range from 5 to 50 newtons, particularly 10 to 45 newtons, preferably 15 to 40 newtons. 
     
     
         16 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized by an abrasion resistance of at least 75%, particularly at least 80%, preferably at least 85%, more preferably at least 90%, most preferably at least 95%. 
     
     
         17 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the carbon black method micropore surface area of the high-performance adsorbents which is formed by pores having pore diameters of ≦20 Å is at least 1000 m 2 /g, particularly at least 1100 m 2 /g, preferably at least 1200 m 2 /g, and/or in that the carbon black method micropore surface area of the high-performance adsorbents which is formed by pores having pore diameters of ≦20 Å is in the range from 1000 to 1800 m 2 /g, particularly 1100 to 1600 m 2 /g, preferably 1200 to 1500 m 2 /g. 
     
     
         18 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the carbon black method micropore surface area of the high-performance adsorbents which is formed by pores having pore diameters of 20 Å comprises at least 30%, particularly at least 40%, preferably at least 50% of the total pore surface area of the high-performance adsorbents, and/or in that the carbon black method micropore surface area of the high-performance adsorbents which is formed by pores having pore diameters of ≦20 Å comprises 50 to 90%, particularly 55 to 85%, preferably 60 to 80% of the total pore surface area of the high-performance adsorbents. 
     
     
         19 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the weight-based adsorbed N 2  volume V ads(wt)  of the high-performance adsorbents, determined at a partial pressure p/p 0  of 0.25, is at least 300 cm 3 /g, particularly at least 350 cm 3 /g, preferably at least 375 cm 3 /g, and is particularly in the range from 300 to 800 cm 3 /g, preferably 350 to 700 cm 3 /g, more preferably 375 to 650 cm 3 /g, and/or in that the volume-based adsorbed N 2  volume V ads(vol)  of the high-performance adsorbents, determined at a partial pressure p/p 0  of 0.25, is at least 75 cm 3 /cm 3 , particularly at least 100 cm 3 /cm 3 , and is particularly in the range from 75 to 300 cm 3 /cm 3 , preferably 80 to 275 cm 3 /cm 3 , more preferably 90 to 250 cm 3 /cm 3 . 
     
     
         20 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the weight-based adsorbed N 2  volume V ads(wt)  of the high-performance adsorbents, determined at a partial pressure p/p 0  of 0.995, is at least 400 cm 3 /g, particularly at least 450 cm 3 /g, and is particularly in the range from 400 to 2300 cm 3 /g, preferably 450 to 2200 cm 3 /g, more preferably 750 to 2100 cm 3 /g, and/or in that the volume-based adsorbed N 2  volume V ads(vol)  of the high-performance adsorbents, determined at a partial pressure p/p 0  of 0.995, is at least 200 cm 3 /cm 3 , particularly at least 250 cm 3 /cm 3 , and is particularly in the range from 200 to 500 cm 3 /cm 3 , preferably 250 to 400 cm 3 /cm 3 , more preferably 275 to 380 cm 3 /cm 3 . 
     
     
         21 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized in that the high-performance adsorbents or to be more precise the grains of activated carbon, particularly spherules of activated carbon, have measure of central tendency particle diameters in the range from 0.01 to 2.0 mm, particularly 0.01 to 1.0 mm, preferably 0.05 to 0.9 mm, more preferably 0.1 to 0.8 mm, most preferably 0.15 to 0.7 mm. 
     
     
         22 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized by an ash content of at most 1%, particularly at most 0.8%, preferably at most 0.6%, more preferably at most 0.5%, and/or characterized by a moisture content of at most 1%, particularly at most 0.5%, preferably at most 0.2%. 
     
     
         23 . The high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims, characterized by a bulk density in the range from 150 to 750 g/l, particularly 175 to 650 g/l, preferably 200 to 600 g/l. 
     
     
         24 . The high-performance adsorbents based on activated carbon in the form of discrete grains of activated carbon, preferably in spherical form, particularly as claimed in one or more of the preceding claims, characterized by the following parameters:
 a pore volume fraction formed by pores having pore diameters of more than 20 Å 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 Å.   a BET surface area of at least 1250 m 2 /g,   a methylene blue value of at least 15 ml, and   a molasses number of at least 300.   
     
     
         25 . The high-performance adsorbents based on activated carbon, particularly as claimed in one or more of the preceding claims, characterized in that the high-performance adsorbents are obtainable by a process as claimed in  claims 26  to  34 . 
     
     
         26 . A process for producing the high-performance adsorbents based on activated carbon, as claimed in one or more of the preceding claims, which process comprises a carbonaceous starting material being initially carbonized and subsequently activated,
 characterized in that   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 CO 2 .   
     
     
         27 . The process as claimed in  claim 26 , characterized in that the first activating step is 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 6 to 15 hours, particularly 6 to 12 hours. 
     
     
         28 . The process as claimed in  claim 26  and/or  27 , characterized in that the second activating step is 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. 
     
     
         29 . The process as claimed in one or more of the preceding claims, characterized in that the atmosphere of the first activating step comprises or consists of water vapor, particularly a mixture of water vapor/inert gas, preferably a mixture of water vapor/nitrogen, particularly where the throughput of water vapor is 25 to 350 m 3 /h, particularly 50 to 300 m 3 /h, based on pure water vapor, and/or particularly where the mass-based throughput of water vapor is 0.01 to 50 l/(h·kg), particularly 0.02 to 25 l/(h·kg), preferably 0.02 to 5 l/(h·kg), reckoned as water and based on the amount of starting material to be activated with water vapor. 
     
     
         30 . The process as claimed in one or more of the preceding claims, characterized in that the atmosphere of the second activating step comprises or consists of CO 2 , particularly of pure CO 2  or a mixture of CO 2 /inert gas, particularly a mixture of CO 2 /nitrogen, particularly where the throughput of CO 2  is 10 to 250 m 3 /h, particularly 20 to 200 m 3 /h, based on pure CO 2 , and/or where the mass-based throughput of CO 2  is 0.001 to 100 m 3 /(h·kg), particularly 0.01 to 50 m 3 /(h·kg), preferably 0.05 to 10 m 3 /(h·kg), reckoned as pure gaseous CO 2  under activating conditions and based on the amount of starting material to be activated with CO 2 . 
     
     
         31 . The process as claimed in one or more of the preceding claims, characterized in that the first and second activating steps merge into each other. 
     
     
         32 . The process as claimed in one or more of the preceding claims, characterized in that the first activating step is carried on to attainment of a predetermined iodine number, particularly to attainment of an iodine number of at least 1000 mg/g, particularly at least 1250 mg/g. 
     
     
         33 . The process as claimed in one or more of the preceding claims, characterized in that the carbonization is carried out at temperatures in the range from 100 to 950° C., particularly 150 to 900° C., preferably 300 to 850° C., and/or for a duration of 0.5 to 6 hours and/or under an inert or at most slightly oxidizing atmosphere. 
     
     
         34 . The process as claimed in one or more of the preceding claims, characterized in that the carbonaceous starting material comprises sulfonated styrene-divinylbenzene copolymers, particularly sulfonated divinylbenzene-crosslinked polystyrenes, particularly in grain form, preferably in spherical form, particularly where the divinylbenzene content of the sulfonated styrene-divinylbenzene copolymers is 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. 
     
     
         35 . The use of the high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims for the food industry, particularly for preparing and/or decolorizing food products. 
     
     
         36 . The use of the high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims for the adsorption of toxins, noxiants and odors, particularly from gas or air streams, or for purifying or cleaning gases, particularly air or liquids, particularly water. 
     
     
         37 . The use of the high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims for use in adsorptive filtering materials, particularly in the manufacture of protective apparel. 
     
     
         38 . The use of the high-performance adsorbents as claimed in one or more of the preceding claims as sorptive storage media for gases or liquids. 
     
     
         39 . The use of the high-performance adsorbents based on activated carbon as claimed in one or more of the preceding claims in the sector of medicine or pharmacy, particularly as a medicament or medicament constituent.