KR20010046104A - Catalyst for reduction of toxic organic compounds from incinerator flue gas and preparing process thereof - Google Patents

Abstract

PURPOSE: Disclosed is a catalyst for oxidizing toxic organic compounds such as polychlorinated dibenzo-p-dioxin, polychlorinated dibenzo furan, polychlorinated biphenyl, and chlorinated benzene emitted during the incineration of municipal waste or medical waste by supporting titanium dioxide substrate (TiO2) having a degree of crystallinity ranging from 2 to 10 with vanadium oxides (V2O5) and palladium oxides (PdO). CONSTITUTION: The preparation method of the catalyst comprises the steps of calcining titanium dioxide in a temperature range of 400 to 600deg.C to obtain titanium dioxide having a degree of crystallinity of 2 to 10; impregnating calcined titanium dioxide in vanadium oxalate solution; vacuum drying it in a temperature range of 100 to 300deg.C for 5-12hrs; impregnating it in palladium nitrate solution; calcining it under air atmospheric condition for 5-15hrs in a temperature range of 400 to 600deg.C. The chemical composition of the prepared catalyst is as follows: 87-94wt.% of TiO2, 6-12wt.% of V2O5, 0.05-1wt.% of PdO.

Description

Catalyst for removing toxic organic compounds from combustion flue gas and its preparation method {Catalyst for reduction of toxic organic compounds from incinerator flue gas and preparing process}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for removing toxic organic compounds from flue gas discharged from a combustion process and a method for producing the same, and more particularly, to polychlorinated dibenzo-p generated from a combustion process such as municipal waste and medical waste incineration. The present invention relates to a catalyst capable of oxidizing and decomposing toxic organic compounds such as dioxins, polychlorinated dibenzofurans, polychlorinated biphenyls, and benzene chlorides, and a method for producing the same.

The polychlorinated dibenzo-p-dioxin, polydibenzofuran, polychlorinated biphenyl and benzene chloride contained in the combustion flue gas are highly toxic and contaminate the environment. It is growing on this day.

Adsorption and washing are the most widely used methods for treating chlorine-based organic compounds contained in combustion flue gases. The adsorption method is a method of adsorbing and removing toxic organic compounds by passing combustion exhaust gas through an adsorbent such as activated carbon or coke, and there is a problem that the toxic organic compounds may eluate when the adsorbents of the toxic organic compounds remaining in the adsorbent are buried. . On the other hand, the cleaning method is a method of washing the combustion flue gas with a chemical solution, which has the disadvantage of generating a large amount of waste water.

Another method to remove toxic organic compounds contained in flue gas is oxidative decomposition using a catalyst. Catalytic oxidative decomposition is a method in which a flue gas passes through a catalyst bed at a constant temperature so that toxic organic compounds react with oxygen to decompose. As the components of the catalyst used in the oxidative decomposition method, a transition metal such as titanium, vanadium, tungsten, molybdenum, chromium, etc. is used. Precious metals such as platinum, palladium, ruthenium and rhodium are also available but are of limited use because of their high cost.

On the other hand, US Patent No. 5,260,044 discloses a method of decomposing dioxins using a honeycomb catalyst in which platinum is supported on a 60 weight titanium dioxide-mullite (TiO _2-3 Al ₂ O ₃ · 2 SiO ₂ ) carrier. However, the catalyst has a disadvantage in that a large space velocity (SV) is required because the decomposition activity is low due to poor dispersibility of the metal supported on the carrier and sintering of the metal component during the thermal firing of the catalyst. have.

Therefore, the technical problem to be achieved by the present invention is to provide a catalyst having a high decomposition activity and a long life for toxic organic compounds contained in the combustion flue gas.

Another technical object of the present invention is to provide a method for preparing the catalyst.

1 is a graph showing the decomposition rate of 1,2-dichlorobenzene according to the reaction time when using the catalyst according to an embodiment of the present invention.

2 is a graph showing the decomposition rate of 1,2-dichlorobenzene according to the reaction time when using the catalyst according to another embodiment of the present invention.

The present invention to achieve the above technical problem,

A catalyst for decomposing toxic organic compounds, characterized in that vanadium oxide (V ₂ O ₅ ) and palladium oxide (PdO) are supported on a titanium dioxide carrier having a crystallinity of 2 to 10.

The present invention to achieve the above other technical problem,

(a) thermosetting the titanium dioxide at 400 to 600 ° C. to adjust the crystallinity to 2 to 10;

(b) impregnating an aqueous solution of vanadium oxalate to the titanium dioxide surface prepared in step (a);

(c) when the resultant of step (b) is vacuum dried at 100 to 300 ℃ for 5 to 12 hours

Keying up;

(d) impregnating the resultant solution of step (c) with an aqueous palladium nitrate solution; And

It provides a method for producing a catalyst comprising the step of (e) calcining for 5 to 15 hours in an air atmosphere of 400 to 600 ℃.

Hereinafter, the present invention will be described in more detail.

Generally, a metal supported catalyst uses a porous oxide as a carrier in order to enhance catalytic activity or increase mechanical strength and thermal stability by interaction between the carrier and the metal. That is, the carrier is required to have a wide surface area, excellent mechanical strength and thermal stability, and the catalyst metal is thinly supported on the support to improve the reaction activity of the entire catalyst.

In particular, titanium dioxide is an oxide capable of partial reduction, and is known as a substance capable of uniformly dispersing the catalytically active component and strongly interacting with the catalytically active component. In addition, depending on the conditions of the reduction treatment can be in the + 3-valent or + 2-valent state, there is a feature that the interaction with the metal is stronger after the reduction treatment. In particular, it exhibits strong interaction with precious metals such as platinum and palladium.

Therefore, in the present invention, titanium dioxide is used as a carrier, palladium which exhibits strong interaction with titanium dioxide and promotes dechlorination of toxic organic compounds, and can provide high decomposition activity at low reaction temperature due to high low temperature activity. Vanadium was used as catalyst metal. In other words, by appropriately adjusting the crystallinity of titanium dioxide to increase the surface area to uniformly carry and support the catalyst metal particles, the palladium particles are not sintered even in the thermoplastic step, thereby maintaining high decomposition activity.

The content of the titanium dioxide is preferably 87 to 94 weight. This is because if the content of titanium dioxide is less than 87 weight, the metal particles may not be evenly dispersed on the surface of the titanium dioxide carrier, and if the content exceeds 94 weight, the metal particles may not be dispersed all over the surface of the titanium dioxide carrier.

The content of the vanadium oxide is preferably 6 to 12 weight, and the content of the palladium oxide is preferably 0.05 to 1 weight.

Hereinafter, the present invention will be described in more detail with reference to embodiments of the present invention.

<Example 1>

50 g of titanium dioxide was thermally baked at 500 ° C. for 10 hours to prepare a powdered titanium dioxide carrier having a crystallinity of 8 measured by X-ray diffraction. A vanadium oxalic acid aqueous solution was prepared by adding 6,8 g of NH ₄ VO ₃ , a vanadium precursor, to a 30 wt. The titanium dioxide powder was impregnated with an aqueous oxalic acid solution.

The resultant was vacuum dried at 100 ° C. for 5 hours, and then impregnated with 0.3 wt% palladium nitrate aqueous solution, and then calcined at 500 ° C. for 10 hours in an air atmosphere to obtain titanium dioxide (90.7 wt.)-Vanadium oxide (9 wt.)-Palladium. (0.3 weight) Supported catalyst was prepared.

1 g of the catalyst was placed in a 10 mm diameter reactor made of Pyrex, and the decomposition rate of 1,2-dichlorobenzene was measured while changing the reaction temperature. The reaction conditions are as follows.

Composition of reaction gas: 1,2-dichlorobenzene 100 ppmv, H ₂ O 5 volumes, oxygen 11 volumes

Space Speed: 24,000 hr ^-1

Reaction temperature: 250, 270, 300, 320, 350, 400 ℃

Reaction pressure: 1 atm

<Comparative Example 1>

The decomposition rate of 1,2-dichlorobenzene was measured by the same method as Example 1 using the catalyst which carried only palladium of 9 weight vanadium, without carrying palladium. The measurement results of Example 1 and Comparative Example 1 are shown in Table 1 below.

Reaction temperature (℃) Decomposition rate () Example 1 Comparative Example 1 250270300320350400 63.980.293.1100100100 29.043.864.780.290.597.3

Table 1 shows that the catalyst of Comparative Example 1 was only 64.7 at 300 ° C., whereas the catalyst of Example 1 exhibited a high decomposition rate of 90 or more at a reaction temperature of 300 ° C. or higher, thereby increasing the decomposition rate by 28.4 or more. Moreover, it can be seen that the catalyst of Example 1 exhibits a decomposition rate of 100 at 320 ° C or higher.

<Example 2>

The 1,2-dichlorobenzene was decomposed for 5 hours at 300 ° C. using the catalyst of Example 1, and the change in decomposition rate over time was observed and shown in a graph (FIG. 1). In spite of the reaction time, the decomposition rate remained almost constant.

<Example 3>

A catalyst was prepared in the same manner as in Example 1 except that the content of palladium was 1 weight and the content of titanium dioxide was 90 weight. The decomposition rate of 1,2-dichlorobenzene according to the reaction temperature was measured and shown in Table 2.

Reaction temperature (℃) Decomposition rate () 300350380400 93.999.99 or more 99.99 or more 99.99 or more

From Table 2, it can be seen that the catalyst of Example 3 also exhibits a decomposition rate of 90 or more at 300 ° C or higher, and an excellent decomposition rate of 99.99 or more at 350 ° C or higher, similarly to the catalyst of Example 1.

<Example 4>

The catalyst of Example 3 was used to decompose 1,2-dichlorobenzene for 5 hours at 300 ° C., and the change in decomposition rate over time was observed to show a graph (FIG. 2). Despite the passage of the reaction time, it can be seen that the decomposition rate remained almost constant.

As described above, the titanium dioxide-vanadium-palladium metal supported catalyst according to the present invention exhibits high decomposition activity against toxic organic compounds such as 1,2-dichlorobenzene, and maintains high catalytic activity even after reaction time. Excellent catalyst properties.

Claims (5)

A catalyst for decomposing toxic organic compounds, characterized in that vanadium oxide (V ₂ O ₅ ) and palladium oxide (PdO) are supported on a titanium dioxide carrier having a crystallinity of 2 to 10. The catalyst according to claim 1, wherein the content of titanium dioxide is 87 to 94 weight. The catalyst according to claim 1, wherein the content of the vanadium oxide is 6 to 12 weight. The catalyst according to claim 1, wherein the content of the palladium oxide is 0.05 to 1 weight. (a) thermosetting the titanium dioxide at 400 to 600 ° C. to adjust the crystallinity to 2 to 10; (b) impregnating an aqueous solution of vanadium oxalate to the titanium dioxide surface prepared in step (a); (c) when the resultant of step (b) is vacuum dried at 100 to 300 ℃ for 5 to 12 hours Keying up; (d) impregnating the resultant solution of step (c) with an aqueous palladium nitrate solution; And (e) calcining the catalyst of claim 1 for 5 to 15 hours in an air atmosphere of 400 to 600 ℃.