CS265331B1 - Process for preparing spherical,macroporous microparticles of carbon - Google Patents

Abstract

One part by weight of the composition comprising 0.13 to 0.29 parts by weight water glass, 0.04 to 0.57 wt parts of sucrose, 0.06 to 0.19 wt parts of hydrogen peroxide and 0.24 to 0.56 parts by weight of water disperses in at least 2.1 parts by weight polypropylene oxide or propoxylated 2,2-bis (hydroxymethyl) -1-butanol and / or block copolymer of oxirane and methyloxirane with a molecular weight of 900 to 10,000 g.mol ”· ^ at 15 to 35 ° C, then removed dispersing medium, the precursor is dried at 60 to 100 ° C and pyrolysed at 450 to 750 ° C.

Description

(57) One part by weight of a mixture comprising 0.13 to 0.29 parts by weight of water glass, 0.04 to 0.57 parts by weight of sucrose, 0.06 to 0.19 parts by weight of hydrogen peroxide and 0.24 to 0.56 parts by weight. of water disperses in at least 2.1 parts by weight of polypropylene oxide or propoxylated 2,2-bis (hydroxymethyl) -1-butanol and / or a block copolymer of oxirane and methyl oxirane having a molar mass of 900 to 10,000 g.mol @ -1 at a temperature of 15 to 35 ° C, then dispersing medium is removed, the precursor is dried at 60 to 100 ° C and pyrolyzed at 450 to 750 ° C.

CS 265 331 B1

The invention relates to a process for preparing spherical, macroporous carbon microparticles.

Several processes for preparing macroporous carbon materials are known for use in separation processes. Colin spolupracovnlkmi to create agglomerates of solid soot particles smaller than ₁ .mu.m. The agglomerates were placed in a quartz tube heated to 900 ° C through which an inert gas (nitrogen) saturated with organic vapors (benzene) flowed. Pyrolysis of benzene on the surface of the agglomerates resulted in partial cementation and hardening. The disadvantage of the resulting material was that it easily disintegrated into originally submicroscopic particles Γ H. Colin, C. Eon, G. Guiochon: J. Chromatogr. 119, 41 (1976)]. By degradation of polytetrafluoroethylene with lithium amalgam, Plzák and co-workers prepared irregular porous carbon particles with a high specific surface area of 2,500 m .g. The shape of the particles and the presence of micropores do not allow efficient use of these materials for the separation processes. Plzak, FP Dousek, J. Jansta: J. Chromatogr. 147, 187 (1978)]. Unger and colleagues used coke and activated carbon as the starting material. Inadequate dimensions of the particles obtained and their irregular shape, as well as the number of pores with a diameter of less than 4 nm, caused this material not to be used in chromatography Κ. Unger K., Roumeliotis P., Mueller H., Gotz H., J. Chromatogr. 202, 3 (1980)]. Gilbert and colleagues used silica gel impregnated with phenol-formaldehyde resin as a porous carbon precursor. After polymerization of the resins, they were subjected to pyrolysis in an inert atmosphere at 1000 ° C. The silica was washed with alkali. In a further procedure, the carbon was heated to 2000 to 2800 ° C in an inert atmosphere. The particle size, shape, pore diameter and porosity is determined by the selection of a silica gel matrix. The surface properties depend on the temperature to which the carbon was exposed Γμ. T. Gilbert, J. Η. Knox, B. Kaur: Chromatographia 16: 138 (1982) J. Berek and Novák prepared a porous carbon-based sorbent using a similar procedure. They used sucrose. The original solid silica gel matrix was eluted with sucrose pyrolysis at 600 ° C (CS AO No. 221 197). The disadvantage of these two processes is the complexity, ie the need to prepare a suitable silica gel matrix, which increases the economic cost.

The above-mentioned disadvantages are substantially eliminated by the process of preparing spherical, macroporous carbon microparticles, which consists in that one part by weight of a mixture containing 0.13 to 0.29 parts by weight of water glass, 0.04 to 0.57 parts by weight of sucrose, 0.06 to 0.19 parts by weight of hydrogen peroxide and 0.24 to 0.56 parts by weight of water are dispersed in at least 2.1 parts by weight of polypropylene oxide or propoxylated 2,2-bis (hydroxymethyl) -1-butanol and / or block of a copolymer of oxirane and methyloxirane having a molar mass distribution in the range of 900 to 10,000 g.mol ¹ at 15 to 35 ° C, then the dispersing medium is removed, the precursor is dried at 60 to 100 ° C and pyrolyzed at 450 to 750 ° C. A mixture of water glass, sucrose and hydrogen peroxide with water forms an emulsion in the macromolecular dispersion medium. The dimensions of the droplets of the mixture of water glass, sucrose, hydrogen peroxide and water in the macromolecular dispersion medium are determined by the intensity of the primary mixing or shaking.

Advantages of the process for preparing spherical, macroporous carbon microparticles include the ability to suitably contain hydrogen peroxide in a liquid mixture of sucrose, water glass, water, and hydrogen peroxide to control the time it takes for the mixture to solidify, which is very important when the process is continualized. A further advantage of this method is that a carbon precursor is prepared in one step, which is highly economically advantageous. In this way, spherical porous carbon particles with less preferred dimensions are obtained. as 60 µm with different surface properties for column packings.

EXAMPLE 1 1 g of distilled water is mixed with 33.366 g of hydrogen peroxide solution having a density of 1.112 2 g.cm. 15 g of sucrose are dissolved in the mixture. To the resulting solution was added 20.55 g of water glass having a molar ratio of silica to sodium oxide of 3.2 with stirring for 1 minute. The mixture is then poured at 15 ° C into 397.12 g of polypropylene oxide having a molar mass distribution of between 900 and 4600 g / mol. Shaking for 30 seconds creates a stable dispersion. Allow to stand for 15 minutes. A mixture of 220 ml of 96 vol. % ethanol / hexane 3: 1 v / v. The mixture was shaken and filtered. The trapped microparticles are washed on the filter with 400 ml of 96 vol. % ethanol and finally 100 ml of hexane. The filter cake is dried in an oven at 60 ° C. After 50 minutes, the obtained precursor is poured into a long-necked glass jar with a ground glass joint. The flask is closed with a ground-glass stopper and placed in a muffle furnace. The temperature is increased incrementally at a rate of 8 ° C per minute to 750 ° C, at which temperature the sample is held for 1 hour. After cooling, the material obtained is poured into 200 ml. % aqueous sodium hydroxide solution and the mixture is allowed to boil.

After boiling for 30 minutes, it is filtered and washed with 650 ml of water. 10 ml (bulk volume) of spherical porous carbon particles of less than 50 .mu.m are obtained. Mercury porosimetry revealed a mean pore size of 12 nm.

Example 2 2 g of water are mixed with 55.61 g of hydrogen peroxide solution with a density of 1.112 2 g.cm. 10 g of sucrose are dissolved in the prepared solution. With vigorous stirring for 1 minute, 27.4 g of water glass is added. At 35 DEG C., the mixture is poured into 297.84 g of propoxylated 2,2-bis (hydroxymethyl) -1-butanol with a molecular weight distribution within the 2500-7000 g.rtDl ^- ''. During shaking for 20 seconds, a dispersion is formed and allowed to stand for 20 minutes. Then 240 ml of 96 vol. % ethanol to hexane in a 4: 1 by volume ratio. The system is shaken and filtered. The filter cake is washed with 500 ml of 96 vol. ethanol and 150 ml of hexane. The product obtained is dried in an oven at 85 ° C. After drying for 35 minutes, the precursor was poured into a long-necked glass flask. The flask is fitted with a gas inlet cap. The flask thus prepared is connected to nitrogen and placed in a muffle furnace. The temperature is increased gradually at a rate of ° C per minute to 600 ° C. This temperature is maintained for 1 hour. After cooling, the contents are poured into 200 ml of 10 wt. % sodium hydroxide solution and then boiled for 25 minutes. It is then washed with 500 ml of water and 100 ml of 96 vol. % ethanol and dried in an oven at 100 ° C. Obtained ml (bulk volume) of porous, spherical particles of carbon with a size _of under 50 microns. Mercury porosimetry revealed a mean pore size of 110 nm.

Example 3

The procedure is as in Example 1 except that 7 g of sucrose is dissolved in 20 g of water and 44.488 g of hydrogen peroxide solution at a density of 1.112 2 g.cm and 20.559 g of water glass are added. The dispersion medium consists of a mixture of 187.36 g of propoxylated 2,2-bis (hydroxymethyl) -1-butanol with a molar mass distribution of between 6,000 and 10,000 g.mol and 25 g of a block copolymer of oxirane and methyloxirane with a molar mass distribution within the limits 5 000 to

500 g.mol. 8 ml (bulk volume) of spherical macroporous carbon particles of less than 50 µm are obtained. Mercury porosimetry revealed a mean pore size of 100 nm.

Example 4

The procedure is as in Example 1 except that 198.56 g of a block copolymer of oxirane and methyloxirane with a molar mass distribution in the range of 2,000 to 9,000 g.mol is used as the dispersing medium. The dispersed mixture is composed of 50 g of sucrose, 27.4 g of 3 water glass, 44.488 g of hydrogen peroxide solution with a density of 1.112 2 g.cm and 20 g of distilled water. The precursor is dried in an oven at 100 ° C. The silica gel is dissolved in 40 ml of a 1 mol / l solution of hydrofluoric acid. 12 ml (bulk) of spherical, macroporous carbon particles of less than 50 .mu.m are obtained. Mercury porosimetry revealed a mean pore size of 2 nm.

Example 5

The procedure is as in Example 1 except that 4 g of sucrose is dissolved in 20 g of water and 44.488 g of hydrogen peroxide solution at a density of 1.112 2 g.cm and 27.4 g of water glass are added. The dispersion medium consists of a mixture of 198.56 g of propoxylated 2,2-bis (hydroxymethyl) -1-butanol with a molar mass distribution in the range of 900 to 5,000 g.mol ¹ and 165.2 g of a block copoly of 265331 oxirane and molar mass methyloxirane. in the range of 6,000 to 10,000 g.mol. The precursor is pyrolyzed at 450 ° C. 8 ml (bulk volume) of spherical, macroporous carbon particles of less than 50 µm are obtained. Mercury porosimetry revealed a mean pore size of 70 nm.

Example 6

The procedure is as in Example 1 except that 893.52 g of a block copolymer of oxirane and methyloxirane with a molar mass distribution in the range of 2,000 to 9,500 g / mol is used as dispersing medium. The dispersed mixture is composed of 120 g of sucrose,

27.4 g water glass, 44.488 g hydrogen peroxide solution with a density of 1.112 2 g.cm and 20 g distilled water. The precursor is pyrolyzed at 540 ° C. The silica gel is dissolved in 40 ml of a mol / l solution of hydrofluoric acid. 12 ml (bulk volume) of spherical, macroporous particles of less than 50 µm are obtained. Mercury porosimetry revealed a mean pore size of 2 nm.

A method for preparing spherical, macroporous carbon particles can find application in organic chemistry in the preparation of carbon column packings for chromatography. The porous carbon obtained can be used as a catalyst carrier in heterogeneous catalysis and as a sorbent in technology and environmental protection.

Claims (1)

OBJECT OF THE INVENTION Process for preparing spherical, macroporous carbon microparticles, characterized in that one part by weight of a mixture comprising 0.13 to 0.29 parts by weight of water glass, 0.04 to 0.57 parts by weight of sucrose, 0.06 to 0.19% by weight parts by weight of hydrogen peroxide and 0.24 to 0.56 parts by weight of water disperse in at least 2.1 parts by weight of polypropylene oxide or propoxylated 2,2-bis (hydroxymethyl) -1-butanol and / or the block copolymer of oxirane and methyloxirane by a molar mass of 900 to 900 parts; 10,000 g.mol ¹ , at a temperature of 15 to 35 ° C, then the dispersion medium is removed, the precursor is dried at a temperature of 60 to 100 ° C, and pyrolyzed at a temperature of 450 to 750 ° C.