JP2902032B2 - Spherical porous carbon particles and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to spherical porous carbon particles. More specifically, the present invention relates to spherical porous carbon particles useful as an adsorbent for gases and organic substances, a carrier for immobilizing a functional substance, a filler for liquid chromatography, and the like.

[Problems to be solved by conventional technology and invention]

Conventionally, porous carbon particles have been used for applications such as catalyst carriers and adsorbents. In recent years, attention has been paid to artificial organs such as artificial livers and artificial kidneys for medical use, and as fillers for liquid chromatography due to the following properties of porous carbon particles, and their use in these has begun to be studied.

 The general characteristics of the porous carbon particles are shown below.

(1) High mechanical strength.

(2) The specific surface area is 50 to 500 m ² / g and has a corresponding sample retention time in liquid chromatography.

(3) It has micropores of 5 nm or more, so that mass transfer is easy.

(4) The interaction sites are uniformly distributed on the particle surface.

(5) A buffer solution having a wide pH range can be used, and the chemical stability is high.

(6) It is theoretically nonpolar inactive.

(7) Good heat resistance.

(8) Form stability.

The above features almost satisfy the conditions required for the above uses such as packing materials for liquid chromatography. The present invention provides carbon particles that can be used as a filler for liquid chromatography.

The method for producing porous carbon particles generally involves press-molding carbon black and a resin binder, carbonizing and calcining, and then crushing the resulting compact to obtain particles having a desired particle size. However, the particles obtained by crushing the molded article cannot be said to be spherical because of the crushed product, and were insufficient as a packing material for liquid chromatography. As a method or carbon source for preliminarily spheroidizing carbon black, impregnating with a binder and calcining to solve this defect,
A method has been proposed in which spherical particles of a synthetic polymer such as polyacrylic resin, polystyrene resin, phenolic resin, polyvinyl chloride, etc. are used to heat-treat and carbonize (see Japanese Patent Application Laid-Open No.
53-48989, JP-A-54-41296).

However, in any of the methods, fixing, breakage, and agglomeration between particles due to melting of a binder or a synthetic polymer occur during baking and heat treatment, and it has been difficult to obtain granular particles.

In order to prevent melting in the heat treatment, treatments such as sulfonation and nitration are performed as described in, for example, JP-A-53-48989, but the effect is not sufficient. Was.

In addition, the carbon particles obtained by such a method cannot be obtained with large pores due to melting in the process of carbonization from the resin, and are extremely inappropriate for separating protein macromolecules. .

In JP-A-59-128207 and JP-A-51-116193, in order to obtain carbon particles having large pores, a second carbon material is used.
A method for adding the component and removing the second component added in the process of granulating and carbonizing is described. However, since the operation is complicated and the second component is of a synthetic resin type, it is described above. It was difficult to obtain spherical particles.

[Means for solving the problem]

The present inventors have noted that cellulose is a substance that does not melt or soften by heating.If cellulose is used as a carbon source, problems such as deformation and sticking of particles in the heat treatment can be solved, and cellulose spherical particles can be solved. It has been found that spherical carbon particles can be easily obtained by dehydration-condensation followed by heat treatment, and that the porosity of the spherical carbon particles obtained can be controlled by the properties of the spherical cellulose used (Japanese Patent Application Flat 1-240564
No.), if the cellulose spherical particles used for this are cross-linked, the diameter of the pores on the surface of the particles is further reduced to 100 mm.
It has been found that spherical porous carbon particles having a peak of the distribution of the number of pores on the particle surface (according to the mercury intrusion method) at a position exceeding the above can be obtained, and the present invention has been completed.

 The present invention includes the following.

(1). Spherical cellulose is a spherical porous carbon particles made from cross-linked spherical cellulose particles obtained by cross-linking between cellulose molecules using a cross-linking agent, the average particle size is 1 to 300 μm
A spherical porous carbon particle having a peak of the distribution of the number of pores (by mercury intrusion method) on the particle surface at a position where the diameter of the pores on the particle surface exceeds 100 mm.

(2). A method for producing spherical porous carbon particles, characterized in that the cellulose molecules of the spherical cellulose particles are cross-linked with a cross-linking agent, dehydration-condensed, and then carbonized and calcined.

The spherical cellulose particles used in the present invention have a true spherical shape, and the production method thereof is as follows, but is not particularly limited.

According to the method described in JP-A-53-86749, cellulose acetate is dissolved in an organic solvent, this solution is suspended in an aqueous solvent to form a sphere, and the organic solvent is evaporated to obtain cellulose ester particles. And a method of producing the cellulose particles after saponification.

A method described in JP-A-56-24429 in which a higher porosity is adjusted by adding an aliphatic higher alcohol or the like to a solution of a cellulose acetate ester by applying the above method.

JP-A-57-159801 in which cellulose is granulated by dissolving it in a mixed solvent of paraformaldehyde and dimethyl sulfoxide
And JP-B-57-159802.

A method described in JP-A-52-11237 in which cellulose is dissolved in concentrated aqueous ammonia containing cupric hydroxide and cuprous chloride for granulation.

Japanese Patent Application Laid-Open (JP) to disperse viscose in transformer oil and granulate
The method described in JP-A-51-5361.

A method described in JP-A-55-44312 in which cellulose is dissolved in a calcium thiocyanate solution and granulated.

A method described in JP-A-48-60754 in which a purified linter is dissolved in a copper ammonia solution and granulated.

A method described in JP-A-61-241337, in which viscose and a water-soluble anionic polymer compound are mixed to form a viscose dispersion, which is heated and solidified.

The spherical cellulose particles used have an average particle diameter of 3 to 300 μm.
m is preferred.

Next, these spherical cellulose particles are crosslinked. When the spherical cellulose particles are cross-linked, the three-dimensional structure of the cellulose is remarkably strengthened by the cross-linking agent, and during the subsequent heat treatment, not only does not cause sticking, agglomeration, and agglomeration between the particles, but also the pores are retained extremely well. Will be

Although there are various methods for crosslinking cellulose, the crosslinking agent (polyhalogen compound, halooxirane, etc.) is used in the presence of an alkaline substance because of the ease of the crosslinking reaction operation, the stability of the crosslinked portion after crosslinking, and the nonionicity. Compounds, polyoxirane compounds, etc.) are generally used. Further, polyfunctional crosslinking agents such as polyamine compounds and polyisocyanate compounds are also useful. For example,
No. 43-10059 describes a method of treating cellulose powder with sodium hydroxide solution to alkali cellulose and then treating with epichlorohydrin. Japanese Chemical Society Journal 1981 (12) P1890-1891 discloses cellulose spherical particles. A method of treating with an aqueous sodium hydroxide solution and then treating with epichlorohydrin is described. JP Hei 1-21
No. 7041 describes a method for obtaining crosslinked cellulose having excellent pressure tightness by crosslinking cellulose in the presence of potassium hydroxide. Either of these methods can be used in the present invention.

When the crosslinked spherical cellulose particles contain water or the like, they are usually dried before use. The drying method is not particularly limited, and examples thereof include a method of removing most of the liquid by filtration and drying by heating, and a method of substituting a solvent such as alcohol, ether or acetone and drying under reduced pressure.

The crosslinked spherical cellulose particles are first subjected to a heat dehydration condensation treatment (preliminary carbonization). This treatment is performed at 100 to 400 ° C., preferably 200 to 300 ° C. for 3 to 6 hours, and can be performed in a vacuum or an inert gas atmosphere, but is performed in the presence of an acid gas, for example, dry hydrogen chloride gas. Is also effective in promoting the reaction.

For carbonizing and firing the crosslinked spherical cellulose particles, it is preferable to heat and fire under an inert gas atmosphere such as nitrogen or argon using an electric furnace or a rotary kiln. For uniform carbonization and firing, a non-fixed furnace such as a rotary kiln or a fluidized bed furnace is desirable. If the firing temperature is too low, carbonization will not proceed, and if it is too high, the progress of carbonization will not be promoted. 2000 ~ 3000 ℃
When the carbonization step is performed, the hardness of the spherical carbon particles obtained by the graphitization increases, the aromatization of cellulose occurring during the carbonization step decreases, and there is an advantage that unnecessary nonspecific adsorption is reduced in the chromatography operation. .
Regarding the temperature rising rate, if the speed is too high, the shape of the spherical particles cannot be maintained, so that the temperature is 5 to 1000 ° C./hour, preferably 50 to 500 ° C.
C / hour is preferred. The firing time depends on the rate of temperature rise. At a heating rate of 50 ° C. to 500 ° C./hour, the desired temperature is reached, and after 0.1 to 24 hours, carbonization firing is achieved. In this way, it is possible to obtain spherical porous carbon particles having an average particle diameter of 1 to 300 μm and having a distribution peak of the number of pores on the particle surface at a position where the diameter of the pores on the particle surface exceeds 100 °. it can.

〔Example〕

Hereinafter, as examples, a method for producing spherical carbon particles using crosslinked spherical cellulose particles as a starting material and examples of use of the obtained particles will be described, but the present invention is not limited to these examples. In the following examples, the average particle size was measured with a Coulter counter (Model TA II manufactured by Coulter Electronics Co., Ltd.).

The pore size was measured by a mercury porosimetry using a pore sizer 9310 (manufactured by Shimadzu Corporation).

(Example 1) 100 g of suction-dried cellulose gel granulated by the method of Example 1 in JP-A-55-44312 was stirred and dispersed in 300 ml of heptane, and a 50% by weight aqueous solution of sodium hydroxide was prepared.
g was added and stirred at room temperature for 6 hours. 30 g of epichlorohydrin was added thereto, and the mixture was further stirred at 50 ° C. for 6 hours. After completion of the reaction, the mixture was filtered and washed with water to obtain spherical crosslinked cellulose particles.

100 g of suction-dried spherical crosslinked cellulose particles were sequentially washed with methanol, ethanol and ether with 240 ml each, and the solvent was replaced. After filtration, the mixture was filtered and vacuum dried with a rotary evaporator. The obtained dried crosslinked cellulose particles are further subjected to drying at 300 ° C. in a dry hydrogen chloride gas atmosphere.
Heat treatment was performed for a time, and a dehydration condensation treatment was performed.

The obtained particles are placed in a nitrogen stream using a rotary kiln for 30 minutes.
The temperature was raised from 0 ° C for 4 hours and from 300 ° C to 1000 ° C in 14 hours.
Carbonization and firing were performed at this temperature for 4 hours to obtain 10 g of spherical carbon particles.

The obtained carbon particles have no sticking, agglomeration and aggregation, the average particle size is 28 μm, and the peak of the distribution of the number of pores on the particle surface is
At 1100 1.

Example 2 200 g of a suction-dried cellulose gel granulated by the method of Example 1 in JP-A-56-24429 was stirred and dispersed in 600 ml of dioxane to give a 50% by weight aqueous solution of potassium hydroxide.
120 g was added, and then 100 g of 1,3-dichloro-2-propanol was added, followed by stirring at 70 ° C. for 6 hours.

After completion of the reaction, the mixture was filtered and washed with water to obtain spherical crosslinked cellulose particles. 190 g of a suction-dried product of the obtained spherical crosslinked cellulose particles was washed with 400 ml of dioxane and 400 ml of ether, and after solvent replacement, vacuum dried with a rotary evaporator. The obtained dried cellulose particles were further subjected to a heat treatment at 350 ° C. for 4 hours in a dry hydrogen chloride atmosphere to carry out a dehydration condensation treatment.

The obtained particles were placed in a fluidized-bed furnace, heated in an argon gas atmosphere to 1000 ° C. for 20 hours and further to 2800 ° C. over 21 hours, and carbonized and calcined at 2800 ° C. for 0.5 hour to obtain 17 g of spherical carbon particles.

The obtained carbon particles have no sticking, agglomeration, agglomeration and an average particle size of 31 μm, and the peak of the distribution of the number of pores on the particle surface is
It was 250Å.

(Example 3) 500 g of suction-dried commercially available spherical crosslinked cellulose particles (Cellulofine (trademark) GCL-1000 type, manufactured by Chisso Corporation) were washed with 2 l of methanol and 1 of ethanol, respectively, and subjected to solvent replacement. After filtration, the mixture was filtered and vacuum-dried with a rotary evaporator. The obtained dried cellulose particles were further subjected to a heat treatment at 300 ° C. for 6 hours in a dry hydrogen chloride gas atmosphere to carry out a dehydration condensation treatment. Then, the particles were washed with 2 l of acetone, filtered, and vacuum-dried with a rotary evaporator.

The obtained particles were heated in an argon gas atmosphere using a rotary kiln in an argon gas atmosphere for 4 hours, from 300 ° C to 1000 ° C for 14 hours, and from 1000 ° C to 2200 ° C for 5 hours.
After firing for carbonization for 50 hours, 50 g of spherical carbon particles were obtained.

The obtained carbon particles have no sticking, agglomeration, aggregation and the average particle size is 10 μm, and the peak of the distribution of the number of pores on the particle surface is
It was 560Å.

(Comparative Example 1) In Example 1, the cellulose gel was used as it was by suction drying without performing cross-linking, and used under exactly the same conditions except for the treatment of cross-linking to obtain 8 g of carbon particles.

The average particle size of the obtained carbon particles was 13 μm, and the peak of the distribution of the number of pores on the particle surface was 62 °.

(Comparative Test 1) In order to compare the particles obtained in Example 1 and Comparative Example 1, a column of φ0.5 mm × 50 mm was packed in a thyroglobulin (molecular diameter of about 190 °) solution (100 mg / 0.01 M phosphoric acid). Buffer (pH 7.0) + 2M NaCl 1ml)
Unadsorbed thyroglobulin eluted by flowing a phosphate buffer (pH 7.0) + 2M NaCl was recovered, and the amount of thyroglobulin adsorbed on the particles was determined.

 Table 1 shows the results.

[Effects of the Invention] As described in detail above, according to the present invention, spherical porous carbon particles having a distribution peak of the number of pores on the particle surface at a position where the diameter of the pores on the particle surface exceeds 100 ° Can be produced in high yield without fixing, agglomerating or aggregating.

The porous carbon particles obtained in this way have a large mechanical strength, a large amount of adsorption and storage time because macromolecules such as proteins can be taken into the pores, and a spherical shape. It is extremely useful as a filler for chromatography and the like.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hideo Kurizaki 4-218, Tsukiji, Minamata-shi, Kumamoto (58) Field surveyed (Int.Cl. ⁶ , DB name) C01B 31/02 B01J 20/20 G01N 30 / 48

Claims (2)

(57) [Claims] 1. Spherical porous carbon particles made from crosslinked spherical cellulose particles obtained by crosslinking between cellulose molecules of spherical cellulose particles using a crosslinking agent, and having an average particle diameter of 1 to 30.
Spherical porous carbon particles having a peak of the distribution of the number of pores (by mercury porosimetry) on the particle surface at a position where the diameter of the pores at the particle surface exceeds 100 ° at 0 μm. 2. A method for producing spherical porous carbon particles, comprising the steps of crosslinking between cellulose molecules of spherical cellulose particles with a crosslinking agent, dehydrating and condensing, and then carbonizing and firing.