JP2799187B2 - Porous graphitic carbon granules and support materials for chromatography using the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION <Industrial Application Field> The present invention relates to porous graphitic carbon granules and a support material for chromatography using the same, in particular, a support material for high performance liquid chromatography. TECHNICAL FIELD The present invention relates to a porous graphitic carbon granule suitable for use and a support material for chromatography using the same.

<Prior Art> Conventionally, in chromatography, particularly high performance liquid chromatography (HPLC), silica gel-based support materials are widely known as materials that can be suitably used for various analyses, for example, for analysis of catecholamines in the human body. Had been. This is because silica gel is formed by a porous skeleton structure, has a sufficiently large surface area, and
This is because it has a compressive strength enough to withstand even when used at a high pressure as described above, and is mechanically stable.

However, even when such a silica gel is used as a support material for chromatography, since the surface of the silica gel itself has a strong polarity, the surface of the silica gel is chemically modified with a compound having a non-polar group to mask the silica gel. There is a problem that a complicated process of using the device after the use must be performed.

On the other hand, as a support material for chromatography other than the silica gel, a carbon material in the form of graphite is known.
However, although the carbon material has low surface chemical properties and extremely stable properties, it has a very small surface area, usually less than 1 m ² / g, and has a mechanical strength such as a compressive strength. There is a problem of poor
In particular, it has been severely restricted from being used as a support material for HPLC.

<Problems to be Solved by the Invention> Accordingly, an object of the present invention is to provide a non-polar and stable chemical property, and suitable for a support material for HPLC having a moderately large surface area and a mechanical strength, particularly a compressive strength. Is to provide a fine granular material.

[Summary of the Invention]

<Summary> In view of the above problems, the present inventors have conducted intensive studies on granules suitable for chromatographic, especially HPLC support materials, and as a result, porous graphite carbonaceous granules having specific properties have been obtained. They found that the body was suitable and completed the present invention.

That is, the present invention provides a porous graphitic carbon granule having the following physical properties.

Average particle size: 5 to 1,000 μm Specific surface area: 10 m ² / g or more Porosity: 5 to 60% Average carbon layer interval (d ₀₀₂ ) determined by X-ray diffraction analysis: 3 to 35 to 3.42 angstroms and A support material for chromatography, comprising porous graphitic carbon granules having the following physical properties.

Average particle size: 1 to 1,000 μm Specific surface area: 10 m ² / g or more Porosity: 5 to 60% Average layer interval (d ₀₀₂ ) of the carbon determined by X-ray diffraction analysis: 3 to 35 to 3.42 angstroms is there.

<Effect> The porous graphitic carbonaceous granules of the present invention are non-polar, have a moderately large specific surface area and mechanical strength, and can be easily manufactured, and the obtained granules are used for chromatography. It is suitable as a support material and can perform chromatographic analysis efficiently.

[Specific description of the invention]

[I] Porous graphitic carbon granules <Properties> The porous graphitic carbon granules of the present invention have an average particle size of 1 to 3.
1000 μm, preferably 5-100 μm, specific surface area 10 m ² / g
The above is preferably 50 m ² / g or more, and the upper limit is not particularly limited, but is preferably about 400 m ² / g. Porosity 5-60
%, Preferably 20 to 50% by weight, and an average layer interval (d ₀₀₂ ) of the carbon determined by X-ray diffraction analysis of 3.35 to 3.42 angstroms, preferably 3.35 to 3.40 angstroms.

Further, the porous graphitic carbon granules have mechanical strength,
In particular, it has a compressive strength of 500 kg / cm ² or more, and is superior in these respects as compared with a conventional graphite-type carbon material.

This granular material is suitably used as it is as a support material for chromatography, but particularly when used as a support material for HPLC, efficient analysis can be performed.

If the average particle size is too small, the packing in the liquid chromatography column becomes too large, which hinders the passage of liquid. On the other hand, if the particle size is too large in the above range, the contact between the liquid and the granular material becomes insufficient because the interval between the granular materials is too large. As a result, efficient analysis cannot be performed.

On the other hand, when the comparative area is too small or the porosity is out of the above range, it is difficult to perform an efficient analysis because the adsorbing power of the substance becomes small. Further, if the average carbon layer interval is larger than the above range, graphitization becomes insufficient, the surface becomes strongly polar, and substances other than the target analyte are also adsorbed. It is unsuitable for use as a support material for analysis. There is no one smaller than the above range.

The average carbon layer interval can be determined by the Bragg equation by measuring the powder X-ray diffraction analysis. Also, the porosity is given by the formula True density of the material measured by helium according to (ρ
_W ) and apparent density (ρ _s ).

Further, the porosity is a ratio of pores having a diameter of about 2 angstroms to about 10 μm in the whole particles.

[II] Production of porous graphitic carbon granules The porous graphitic carbon particles of the present invention can be produced, for example, by the following method.

That is, a specific surface area of 10 m ² / g or more of a vapor-grown carbon fiber and a medium containing a carbonizable binding substance for binding the same are mixed, granulated, and then fired in a non-oxidized state. Thus, an object can be manufactured.

<Vapor-grown carbon fiber> As the vapor-grown carbon fiber used in the above method, a carbon source such as a hydrocarbon or carbon monoxide is contacted in the presence of a transition metal ultrafine particle catalyst such as Fe or Co to form a gas. It is a fibrous graphitic carbon material obtained by phase growth or obtained by heating it. Since carbon fibers other than these vapor-grown carbon fibers have a small specific surface area and are slightly inferior in graphitization degree, it is preferable to use vapor-grown fibers.

The specific surface area of the vapor grown carbon fiber used for producing the porous graphitic carbon granules of the present invention is at least 10 m ² / g, preferably at least 50 m ² / g in the specific surface area measured by the BET method. Things. The upper limit is not particularly limited, but is preferably 400 m
It is about ² / g.

Thus, as a method for producing a suitable high specific surface area (50 m ² / g or more) vapor grown carbon fiber, for example,
The method detailed in the specification of Japanese Patent Application No. 63-322431 can be employed.

Specifically, a carbon source compound is supplied to a heating zone in a reaction tube together with a carrier gas, and a transition metal carbonyl compound is obtained by gas phase pyrolysis in the presence of at least one organic compound containing oxygen and / or sulfur. The whisker can be produced by decomposing the carbon source compound in a gas phase space in the presence of a catalyst comprising ultrafine transition metal particles.

The diameter and length of the vapor-grown carbon fiber are selected from appropriate materials according to the diameter of the final support material, and the diameter is usually 5 μm or less, preferably 0.01 μm or less.
~ 2μm, fiber length is 1mm or less, preferably 500 ~ 1μ
It is preferable to use one having a range of m.

<Carbonizable binder> The carbonizable binder described above binds the vapor grown carbon fibers to each other during mixing and granulation. Examples of such a carbonizable binder include thermosetting resins such as phenolic resins (such as resol resins and novo hook resins), furan resins, acrylic resins, epoxy resins, and unsaturated polyester resins, or ABS resins and polycarbonate resins. And a thermoplastic resin such as a polypropylene resin. Also, pitch, tar, and the like can be used. Among them, it is preferable to use a phenol resin having a relatively high carbonization yield, especially a liquid phenol resin or pitch.

<Diluting medium> Examples of the diluting medium used for forming the carbonizable binder into a solution or a dispersion include water, methanol,
Tetrahydrofuran, pyridine, quinoline, benzene,
Examples include toluene. The concentration of the carbonizable binder in the diluting medium is determined by the type of the carbonizable binder, the type of the diluting medium including the solvent or the dispersion medium, the surface area of the vapor grown carbon fiber mixed with the diluting medium, It varies depending on the average fiber length, the porosity of the obtained porous granular material as the target substance, mechanical properties, and the like, but is usually 5 to 60% by weight, preferably 10 to
Usually, it is performed within the range of 30% by weight.

<Other Additives> In addition, a pore formation promoter can be optionally used for the purpose of imparting continuous pores to the target substance or increasing the porosity. As such a pore formation promoter, a substance that is decomposed and gasified by firing in a non-oxidizing atmosphere and hardly remains as a carbon component can be used. For example, starch,
Examples include cellulose, polyethylene oxide and polyvinyl alcohol. The addition of the pore formation promoter can be carried out in a diluting medium comprising a solution or a dispersion medium of the above-described carbonizable binder.

<Granulation> The method of granulating the mixture of the vapor-grown carbon fiber and the diluting medium containing the carbonizable binder can be granulated by a known method. For example, there is a method of granulating by dropping into a non-soluble medium such as a sulfuric acid bath with a pore nozzle, or a method of coagulating while stirring and then solidifying with a hardener or the like to granulate.

<Firing> The granulated composition is desirably fired after drying to carbonize a carbonizable binder substance as a binder to graphitize. The firing is performed by heating in a non-oxidizing inert gas such as nitrogen or argon. Heating temperature is 800-3
The heating is usually performed in the range of 000 ° C, preferably 1000 to 2500 ° C, and the heating time is in the range of 5 to 20 hours.

[III] Utilization as a chromatographic support material Since the porous graphitic carbon granules produced as described above have the above-mentioned properties, they are used as chromatographic support materials, particularly high-performance liquid chromatography ( It is suitable as a support material for HPLC).

In order to use the porous graphitic carbon granules as a support material for a liquid chromatographer, they may be filled as they are or after impregnating with various adsorbents, into a column made of a stainless steel tube or the like.

(Experimental example)

Example 1 <Production of granular material> 3 g of a commercially available water-soluble phenol resin having a fixed amount of 65% by weight
Was dispersed in 3 l of water and dissolved by heating. 100 g of vapor grown carbon fiber (specific surface area: 130 m ² / g, average diameter: 0.2 μm, average fiber length: 2 μm) was added thereto. Next, 0.2 g of sodium alginate was added thereto, and the mixture was uniformly dissolved. Then, the solution was dropped from a nozzle into a 10% aqueous calcium chloride solution stirred at a rotation speed of 500 prm to form spherical gel particles. Was.

After filtering the obtained spherical particles, it was vacuum-dried at room temperature. Next, the spherical particles are first heated to 100 ° C in a nitrogen stream.
For 2 hours, then raise the temperature to 1000 ° C at a rate of 70 ° C / hr, keep it constant at a temperature of 1000 ° C for 6 hours, further raise the temperature, and heat at a temperature of 2000 ° C for 15 minutes did.

<Physical Properties> As a result of observation of the product by an electron microscope, spherical particles shown in FIG. 1 were obtained. The spherical particles have an average particle size of 5 μm and a porosity.
It was 48% by weight, and no defects such as cracks could be observed.

Further, the specific surface area was 73 m ² / g, and it was found to have a graphite structure having an average carbon layer interval (d ₀₀₂ ) of 3.37 Å by X-ray diffraction spectrum measurement.

<Use as Chromatography Support Material> The above granular material was packed as a chromatography support material in a stainless steel tube having an inner diameter of 4 mm and a length of 150 mm to obtain a separation column. Add 1 ml of dichloromethane per minute to this separation column.
The mixture was subjected to liquid chromatography by flowing at a flow rate of, and a mixture of nitrobenzene, o-cresol and m-cresol was injected into the liquid chromatography.

As a result, as shown in FIG. 2, these three components were all eluted without being adsorbed. From this, it can be understood that the support material for chromatography of the present invention is extremely inert.

A 0.1% aqueous solution of trichloroacetate was passed through the separation column at a flow rate of 1 ml / min to perform liquid chromatography, and a mixture of insulin, lysozyme, BSA, myoglobin, and ovalbumin was injected into the column.

As a result, each component was sequentially eluted from the one with the larger molecular weight. Therefore, it was found that the support material for chromatography of the present invention can be used as a filler for GPC.

[Brief description of the drawings]

FIG. 1 is a drawing showing the particle structure of the porous graphitic carbon granules of Example of the present invention at a magnification of 2000 times by an electron micrograph. FIG. 2 shows that nitrobenzene, o-cresol and m were used as support materials for chromatography.
4 is a chromatograph in which the degree of adsorption of a mixture comprising cresol was measured.

(56) References JP-A-60-152569 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C01B 31/04 C09C 1/56 G01N 30/48

Claims (2)

(57) [Claims] 1. A porous graphitic carbon granule having the following physical properties. Average particle size: 5 to 1,000 μm Specific surface area: 10 m ² / g or more Porosity: 5 to 60% Average carbon layer interval (d ₀₀₂ ) determined by X-ray diffraction analysis: 3 to 35 to 3.42 angstroms 2. A support material for chromatography comprising porous graphitic carbon granules having the following physical properties. Average particle size: 1 to 1,000 μm Specific surface area: 10 m ² / g or more Porosity: 5 to 60% Average layer interval (d ₀₀₂ ) of the carbon determined by X-ray diffraction analysis: 3 to 35 to 3.42 angstroms