Process For Manufacturing Spherical Activated Carbon

Abstract

A process for manufacturing a spherical activated carbon, characterized by comprising the steps of: (1) forming a spherical substance of a heat-fusible resin, (2) oxidizing the spherical substance of a heat-fusible resin to form a heat-infusible spherical substance, and (3) activating the heat-infusible spherical substance to form the spherical activated carbon is disclosed. According to the process for the manufacture, a spherical activated carbon having desirable properties, such as an average particle diameter, a particle size distribution, a pore volume, or a specific surface area, can be easily prepared.

Description

EXAMPLES

The present invention now will be further illustrated by, but is by no means limited to, the following Examples.

Example 1

Deionized water (220 g) and methyl cellulose (58 g) were charged into a 1 L separable flask. Further, 105 g of styrene, 184 g of divinyl benzene with a purity of 57% (57% divinylbenzene and 43% ethylvinyl benzene), 1.68 g of 2,2′-azobis(2,4-dimethylvaleronitrile), and 63 g of 1-butanol as a porogen were added thereto. Then, a replacement with a nitrogen gas was carried out. The two-phase system was stirred at 200 rpm, and heated to 55° C., and then allowed to stand for 20 hours. The resulting resin was filtered, and dried in a rotary evaporator. In a vacuum dryer, 1-butanol was removed from the resin by distillation, and the product was dried under a reduced pressure at 90° C. for 12 hours to thereby obtain a spherical porous synthetic resin having an average particle diameter of 180 μm. A specific surface area of the porous synthetic resin was about 90 m²/g.

The resulting spherical porous synthetic resin (100 g) was charged into a reactor having a grating, and treated to impart infusibility in a vertical tubular furnace. The infusibility-imparting treatment was carried out under the conditions that dried air (3 L/min) was upwardly passed from the lower portion of the reactor tube, the temperature was raised to 260° C. at a rate of 5° C./h, and the whole was allowed to stand at 260° C. for 4 hours to thereby obtain a spherical porous oxidized resin. The resulting spherical porous oxidized resin was heat-treated at 600° C. for 1 hour under a nitrogen atmosphere, and then activated in a fluidized bed at 820° C. for 10 hours under a nitrogen gas atmosphere containing 64.5% by volume of steam, to obtain a spherical activated carbon. The properties of the resulting spherical activated carbon are shown in Table 1.

Then, the resulting spherical activated carbon was oxidized in the fluidized bed at 470° C. for 195 minutes under a nitrogen-oxygen atmosphere containing 18.5% by volume of oxygen, and reduced in the fluidized bed at 900° C. for 17 minutes under a nitrogen gas atmosphere, to obtain a surface-modified spherical activated carbon. The properties of the resulting surface-modified spherical activated carbon are listed in Table 2.

Example 2

The procedures of Example 1 were repeated except that the two-phase system was stirred at 100 rpm, instead of 200 rpm, to obtain a spherical activated carbon and a surface-modified spherical activated carbon. The properties of the resulting spherical activated carbon are listed in Table 1, and the properties of the surface-modified spherical activated carbon are listed in Table 2.

Example 3

The procedures of Example 1 were repeated except that the two-phase system was stirred at 150 rpm, instead of 200 rpm, to obtain a spherical activated carbon and a surface-modified spherical activated carbon. The properties of the resulting spherical activated carbon are listed in Table 1, and the properties of the surface-modified spherical activated carbon are listed in Table 2.

Example 4

The procedures of Example 1 were repeated except that the two-phase system was stirred at 300 rpm, instead of 200 rpm, to obtain a spherical activated carbon and a surface-modified spherical activated carbon. The properties of the resulting spherical activated carbon are listed in Table 1, and the properties of the surface-modified spherical activated carbon are listed in Table 2.

Example 5

The procedures of Example 1 were repeated except that the activation was carried out for 6 hours, instead of 10 hours, to obtain a spherical activated carbon and a surface-modified spherical activated carbon. The properties of the resulting spherical activated carbon are listed in Table 1, and the properties of the surface-modified spherical activated carbon are listed in Table 2.

Example 6

The procedures of Example 1 were repeated except that the activation was carried out for 13 hours, instead of 10 hours, to obtain a spherical activated carbon and a surface-modified spherical activated carbon. The properties of the resulting spherical activated carbon are listed in Table 1, and the properties of the surface-modified spherical activated carbon are listed in Table 2.

[Method for Evaluation of the Spherical Activated Carbon and the Surface-Modified Spherical Activated Carbon]

The properties shown in the following Table 1 (spherical activated carbon) and Table 2 (surface-modified spherical activated carbon) were measured by the following methods.

(1) Average Particle Diameter

The laser diffraction apparatus for measuring particle size distribution as mentioned above was used for the measuring.

(2) Pore Volume

The spherical activated carbon or the surface-modified spherical activated carbon prepared in Examples 1 to 5and Comparative Examples 1 to 4 was measured by the mercury injection method as mentioned above.

(3) Specific Surface Area by BET or Langmuir's Method

The BET or Langmuir's method as mentioned above was used for the measuring.

(4) Bulk Density

The sample was charged into a 50 mL graduated measuring cylinder until the sample reached a scale of 50 mL. After the cylinder was tapped 50 times, a weight of the sample was divided by a volume of the sample to find a bulk density. The results are shown in Tables 1 and 3. It was confirmed that the results obtained by the above method were equal to those obtained by the method for determining a packing density in accordance with JIS K 1474-5.7.2 in the range of the significant figures shown in Tables 1 and 2.

(5) Total Amount of Acidic Groups and Total Amount of Basic Groups

The surface-modified spherical activated carbon sample (1 g), which comprised particles having a size of 200 mesh or less prepared by crushing, was added to 50 mL of a 0.05N NaOH solution (total amount of acidic groups) or 50 mL of a 0.05N HCl solution (total amount of basic groups). After the mixture was shaken for 48 hours, the surface-modified spherical activated carbon sample was filtered out, and titrated until neutralization to find an amount of NaOH consumed (total amount of acidic groups) or an amount of HCl consumed (total amount of basic groups). The results are shown in Table 2.

	TABLE 1
	Average		Specific surface
	particle diameter		area
		Length			Langmuir	BET	Bulk
	Dv50	D1	Weight D4		method	method	density
	(μm)	(μm)	(μm)	D4/D1	(m2/g)	(m2/g)	(g/mL)
Example 1	Cross-linked	117	118	133	1.12	2407	1906	0.50
	vinyl resin
Example 2	Cross-linked	198	168	196	1.16	2451	1978	0.50
	vinyl resin
Example 3	Cross-linked	150	142	156	1.09	2380	1921	0.50
	vinyl resin
Example 4	Cross-linked	70	67	74	1.11	2422	1955	0.50
	vinyl resin
Example 5	Cross-linked	119	119	135	1.14	1443	1177	0.63
	vinyl resin
Example 6	Cross-linked	117	128	132	1.03	2715	2210	0.47
	vinyl resin

	TABLE 2
	Average		Specific surface
	particle diameter		area		Total	Total
		Length			Langmuir	BET	Bulk	acidic	basic
	Dv50	D1	Weight D4		method	method	density	groups	groups
	(μm)	(μm)	(μm)	D4/D1	(m2/g)	(m2/g)	(g/mL)	(meq/g)	(meq/g)
Example 1	Cross-linked	111	104	129	1.24	2147	1763	0.50	0.59	0.61
	vinyl resin
Example 2	Cross-linked	168	161	184	1.14	2206	1809	0.50	0.60	0.58
	vinyl resin
Example 3	Cross-linked	131	131	144	1.10	2142	1756	0.50	0.62	0.63
	vinyl resin
Example 4	Cross-linked	63	62	69	1.11	2180	1788	0.50	0.55	0.60
	vinyl resin
Example 5	Cross-linked	93	95	105	1.10	1614	1282	0.63	0.53	0.57
	vinyl resin
Example 6	Cross-linked	100	101	114	1.13	2259	1858	0.47	0.65	0.60
	vinyl resin

INDUSTRIAL APPLICABILITY

According to the process of the present invention, the spherical activated carbon having desired properties, such as the average particle diameter, the particle size distribution, the pore volume, or the specific surface area, can be easily obtained. Further, from the above spherical activated carbon, the surface-modified spherical activated carbon having desired properties, such as the average particle diameter, the particle size distribution, the pore volume, or the specific surface area, can be easily obtained.

Although the present invention has been described with reference to specific embodiments, various changes and modifications obvious to those skilled in the art are possible without departing from the scope of the appended claims.

Claims

1. A process for manufacturing a spherical activated carbon, comprising the steps of: (1) forming a spherical substance containing heat-fusible resin,(2) oxidizing the spherical substance of the heat-fusible resin to form a heat-infusible spherical substance, and(3) activating the heat-infusible spherical substance to form the spherical activated carbon.

2. The process according to claim 1, for manufacturing the spherical activated carbon wherein an average particle diameter is 0.01 to 1 mm, a specific surface area determined by a BET method is 700 m2/g or more, and a volume of pores having a diameter of 7.5 to 15000 nm is 0.01 mL/g to 1 mL/g.

3. The process according to claim 1, further comprising the step of: oxidizing and reducing the spherical activated carbon to form a surface-modified spherical activated carbon.

4. The process according to claim 3, for manufacturing the surface-modified spherical activated carbon wherein an average particle diameter is 0.01 to 1 mm, a specific surface area determined by a BET method is 700 m2/g or more, a volume of pores having a diameter of 7.5 to 15000 nm is 0.01 mL/g to 1 mL/g, a total amount of acidic groups is 0.30 to 1.20 meq/g, and a total amount of basic groups is 0.20 to 0.90 meq/g.

5. The process according to claim 1, wherein the heat-fusible resin is cross-linked vinyl resin.

6. The process according to claim 1, wherein the specific surface area of the spherical substance of the heat-fusible resin is 10 m2/g or more.

7. The process according to claim 1, wherein the content of elements other than carbon atom, hydrogen atom, and oxygen atom in the heat-fusible resin is 15% by weight or less.

8. The process according to claim 1, wherein the spherical activated carbon for an adsorbent for oral administration is prepared.

9. The process according to claim 2, wherein the spherical activated carbon for an adsorbent for oral administration is prepared.

10. The process according to claim 5, wherein the spherical activated carbon for an adsorbent for oral administration is prepared.

11. The process according to claim 6, wherein the spherical activated carbon for an adsorbent for oral administration is prepared.

12. The process according to claim 7, wherein the spherical activated carbon for an adsorbent for oral administration is prepared.

13. The process according to claim 3, wherein the heat-fusible resin is cross-linked vinyl resin.

14. The process according to claim 3, wherein the specific surface area of the spherical substance of the heat-fusible resin is 10 m2/g or more.

15. The process according to claim 3, wherein the content of elements other than a carbon atom, a hydrogen atom, and an oxygen atom in the heat-fusible resin is 15% by weight or less.

16. The process according to claim 3, wherein the surface-modified spherical activated carbon for an adsorbent for oral administration is prepared.

17. The process according to claim 4, wherein the surface-modified spherical activated carbon for an adsorbent for oral administration is prepared.

18. The process according to claim 9, wherein the surface-modified spherical activated carbon for an adsorbent for oral administration is prepared.

19. The process according to claim 10, wherein the surface-modified spherical activated carbon for an adsorbent for oral administration is prepared.

20. The process according to claim 11, wherein the surface-modified spherical activated carbon for an adsorbent for oral administration is prepared.