KR100417685B1 - A method of preparing an activated carbon fiber based catalyst for decomposition of PCDDs - Google Patents

Abstract

The present invention relates to a method for producing an activated carbon fiber-based decomposition catalyst, comprising the steps of impregnating a fine powder pulverized in an aqueous solution of copper, cobalt, chromium compounds, drying the mixture below the softening temperature of the pitch, A method of producing an activated carbon-based organochlorine decomposition catalyst comprising the step of melt spinning the dried mixture to produce a pitch fiber in which the metal compound is uniformly dispersed and stabilizing the prepared pitch fiber in a conventional manner; and As a catalyst produced by the production method, the present invention relates to a catalyst capable of decomposing polychlorodibenzoparadioxin (PCDD) more efficiently than before by increasing the specific surface area of the catalyst.

Description

A method of preparing an activated carbon fiber based catalyst for decomposition of PCDDs}

The present invention relates to a method for producing an activated carbon fiber-based decomposition catalyst, and more particularly, in the production of activated carbon fibers, a pitch powder is impregnated with a water-soluble metal and dried to disperse the metal to disperse the polychlorodibenzoparadioxin. A method for producing an activated carbon fiber-based decomposition catalyst capable of decomposing (PCDD).

The organic chlorine compound is a toxic substance that is mixed with impurities in the manufacture of agrochemicals or is produced during the incineration of synthetic resins such as PVC mainly in waste incinerators. PCDF), polychlorobiphenyl (PCB), and the like, which are decomposed when reacted at a high temperature of 700 ° C. or higher, but additional processing and energy are required to process at such a high temperature.

Therefore, when the reaction temperature is heat-treated at a temperature as low as 300 ° C or less can reduce the required energy. In this regard, see Hiraoka et al., Chemosphere, Vol. 19, Nos. 1-6, p 361-366, 1989 has proposed a method using a honeycomb-type platinum catalyst, but there is a disadvantage in that the treatment cost is considerably high.

In addition, as shown by Hagenmaier et al. In Organohalogen Compound 3, p 65-68, it shows the result of decomposing dioxins using TiO ₂ -based catalysts at temperatures below 400 ° C. It was difficult to disassemble.

In Korean Patent Application Nos. 96-67966 and 96-68742, the pitch of activated carbon fibers can be used as a catalyst to effectively decompose PCDD. When copper and cobalt are supported on the surface, the self-catalytic action of the activated carbon fibers and the It is reported that the decomposition efficiency is improved by the catalyst promoting action of each metal by the specific surface area.

However, since this method uses activated carbon fibers, the catalyst component is impregnated only on the surface of the activated carbon fiber, which is relatively more efficient than the activated carbon system, and finely impregnated with the metal mixture on the surface of the activated carbon fiber composed of only micropores. As the pores are closed, the specific surface area is remarkably lowered, and the metal component is not diffused into the micropores, thereby insufficiently exhibiting the activity of the catalyst. As a result, there is a problem in that the porosity of the activated carbon fibers is not sufficiently exhibited.

The present invention has been made to solve the above problems, when producing a carbon fiber by using a pitch, polychlorodibenzoparadioxin by spreading the specific surface area of the catalyst by uniformly dispersing the metal compound in the interior as well as the fiber surface It is to provide a method for producing a catalyst for decomposing (PCDD).

The present invention to achieve the object as described above,

a) impregnating a pitch pulverized into fine powder into an aqueous solution of a copper, cobalt and chromium compound;

b) drying said mixture below the softening temperature of the pitch;

c) melt spinning the dried mixture to produce pitch fibers in which metal compounds are uniformly dispersed; And

d) stabilizing the prepared pitch fibers in an air atmosphere

It provides a method for producing an activated carbon fiber-based decomposition catalyst comprising a.

Hereinafter, the present invention will be described in detail.

If the pitch used in the present invention is a physical property that can be used to produce pitch fibers alone, both petroleum and coal tar can be used, but isotropic pitch is preferably used as a raw material.

It is preferable that the softening point of the said raw material pitch is 150-350 degreeC.

If the softening point of the raw material pitch is too low in the production of ordinary carbon fibers or activated carbon fibers, the yield is low and the mechanical properties such as tensile strength of the final product are lowered. In this case, since the metal component is re-melted in the spinning process after being impregnated and dried, it is preferable to use a pitch of relatively high softening point so that phase separation between the impregnated component and the pitch does not occur in this step. In addition, when the softening point of the pitch is too high, it is difficult to maintain isotropy, which is a tissue structure that is advantageous for activation. However, when the pitch is less than 350 ° C., it is preferable because only part is anisotropic and activation is possible, and isotropy is maintained and sufficient spinning is possible. In the case of pitch melted so that there is no limitation of the softening point.

Pitch is preferred because pulverizing as much as possible can impregnate a large amount of the metal component and also distribute the metal component uniformly in the catalyst.

As a metal compound for dispersing a metal component in the carbon fiber using the pitch, water-soluble copper, cobalt, and chromium-based compounds are impregnated into the carbon fiber in the form of a saturated aqueous solution.

The impregnated mixture is dried below the softening temperature of the pitch at a temperature at which the pitch does not melt prior to spinning. When the softening point of the pitch is low, it is possible to effectively dry at low temperature by using means such as vacuum drying.

The dried pitch may be spun by methods such as melt spinning and centrifugal spinning, which are spinning methods in ordinary carbon fiber manufacturing methods, but melt spinning methods are preferred, and the impregnated in the molten pitch is made by reducing the part of the molten state in spinning. It is desirable to minimize the phase separation of the metal component and the pitch.

Pitch fiber after spinning in the air atmosphere Stabilized, carbonized and activated to make activated carbon fibers. If necessary, it is also possible to increase the content of the metal component by impregnating the prepared activated carbon fiber catalyst again, but at this time, it is not preferable to overtreat because the pores can be closed.

The conventional method for producing activated carbon fibers is a method of stabilizing by heat treatment for 1 to 10 hours in an oxidizing atmosphere of about 200 to 300 ℃ and carbonization in an inert atmosphere at a temperature of 700 to 1000 ℃ steam or at a temperature of 700 to 1000 ℃ It includes a method of activating in a carbon dioxide or air atmosphere, and if the carbonization process is omitted and directly activated, carbonization and activation occur at the same time, but this is not preferable because the yield may be lower than when carbonized separately.

In the activated carbon fiber-based decomposition catalyst of the present invention, copper, cobalt, and chromium are uniformly distributed on the surface and inside of the carbon fiber, so that the specific surface area is increased, so that polychloroparadioxin (PCDD) can be efficiently decomposed.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are only presented to aid the understanding of the present invention, and the present invention is not limited to the following examples.

Example 1

Isotropic coultar pitch with a softening point of 210 ° C was pulverized to 325 mesh or less (44 μm or less), impregnated in a saturated aqueous solution of copper sulfate [CuSO ₄ ㆍ 5H ₂ O], and then vacuum dried at 50 ° C at 235 ° C in a melt spinning machine. Spinning produced pitch fibers in which copper sulfate was uniformly dispersed in the fiber. The fibers were thermally stabilized at 240 ° C. for 3 hours in an air atmosphere and then carbonized at 800 ° C. for 30 minutes in a nitrogen gas atmosphere to prepare carbon fibers. It was activated at 900 ° C. for 1 hour in an excess of steam atmosphere to prepare an activated carbon fiber-based catalyst. The specific surface area of the prepared activated carbon fibers was 1520 m 2 / g.

Using this activated carbon fiber catalyst, according to Organohalogen Compound 3 of Hagenmaier et al. The reaction was carried out at 300 ° C. and the composition of the gas after the reaction was analyzed by gas chromatography. The packing density of the catalyst was maintained at 0.2 g / cm 3 and the space velocity at this time was 2500 h ⁻¹ . As a result, the decomposition rate was 90% compared to the initial concentration of the feed gas.

Example 2

An activated carbon fiber catalyst was prepared in the same manner as in Example 1, except that cobalt nitrate [Co (NO ₃ ) ₂ .6H ₂ O] was used instead of the aqueous copper sulfate solution in Example 1. The specific surface area of the prepared activated carbon fibers was 1492 m 2 / g.

Using this activated carbon fiber catalyst, tetrachloroethylene was vaporized and reacted with a gas maintained at a concentration of 1000 ppm at 300 ° C., and the composition of the gas after the reaction was continuously analyzed by a gas chromatography method. The packing density of the catalyst was maintained to be 0.2 g / cm 3, and the space velocity at this time was 2500 h ⁻¹ . As a result, the decomposition rate was 81% compared to the initial concentration of the feed gas.

Example 3

An activated carbon fiber catalyst was prepared in the same manner as in Example 1, except that chromium (III) [CrN ₃ O ₉ .9H ₂ O] was used instead of the aqueous copper sulfate solution in Example 1. The specific surface area of the prepared activated carbon fibers was 1555 m 2 / g.

Tetrachloroethylene was vaporized using the activated carbon fiber catalyst to react with a gas maintained at a concentration of 1000 ppm at 300 ° C., and the composition of the gas after the reaction was continuously analyzed by a gas chromatography method. The packing density of the catalyst was maintained to be 0.2 g / cm 3, and the space velocity at this time was 2500 h ⁻¹ . As a result, the decomposition rate was 92% compared to the initial concentration of the feed gas.

Comparative Example 1

Pitch fibers were prepared by pulverizing an isotropic coal tar pitch having a softening point of 210 ° C. to 325 mesh or less (44 μm or less) and spinning at 235 ° C. in a melt spinning machine. The fibers were heat stabilized at 240 ° C. for 3 hours in an air atmosphere having the same conditions as in Example 1, and carbonized at 800 ° C. for 30 minutes in a nitrogen gas atmosphere to prepare carbon fibers. It was activated at 900 ° C. for 1 hour in an excess of steam atmosphere to prepare an activated carbon fiber-based catalyst. The specific surface area of the prepared activated carbon fibers was 1565 m 2 / g. This activated carbon fiber was impregnated into a saturated aqueous solution of copper sulfate [CuSO ₄ .5H ₂ O], and then dried at 150 ° C. for 2 hours. The specific surface area of the activated carbon fiber catalyst at this stage was reduced by about 27% to 1138 m 2 / g.

Tetrachloroethylene was vaporized using the activated carbon fiber catalyst to react with a gas maintained at a concentration of 1000 ppm at 300 ° C., and the composition of the gas after the reaction was continuously analyzed by gas chromatography. The packing density of the catalyst was maintained at 0.2 g / cm 3 and the space velocity at this time was 2500 h ⁻¹ . As a result, the decomposition rate was 72% compared to the initial concentration of the feed gas.

In the case of using the activated carbon catalyst according to the present invention, since the specific surface area of the catalyst is widened, it can be seen that the decomposition rate of the PCDD is increased by about 10 to 20%, compared to the conventional case. Can be disassembled.

Claims (4)

delete a) impregnating a pitch pulverized into fine powder into an aqueous solution of a copper, cobalt and chromium compound; b) drying said mixture below the softening temperature of the pitch; c) melt spinning the dried mixture to produce pitch fibers in which metal compounds are uniformly dispersed; And d) stabilizing the prepared pitch fibers in an air atmosphere Method for producing an activated carbon-based decomposition catalyst comprising a. The method of claim 2, The softening point of the raw material pitch is 150 to 350 ℃ a method for producing an activated carbon decomposition catalyst. Activated carbon-based decomposition catalyst prepared according to the method of claim 2 or 3.