KR20100069213A - The apparatus and method on the treatment of volatile organic compounds using gliding arc plasma-catalyst process - Google Patents

Abstract

PURPOSE: A volatile compound processing device using gliding arc discharge and a method thereof are provided to activate a catalyst without an additional heating source by combining a catalyst layer on an outlet of an arc discharge reactor. CONSTITUTION: A volatile compound processing device includes the following: a gliding arc discharge reaction part(10) including an electrode; a catalyst reaction part(20) formed on an outlet of the gliding arc discharge part; and a power supply part. The gliding arc discharge reaction part forms discharge of a whirlpool shape by guiding turbulent flow on the gas. The power supply part supplies an AC power source to the gliding arc discharge reaction part. The catalyst reaction part includes metal oxides.

Description

The Apparatus and Method on The Treatment of Volatile Organic Compounds Using Gliding Arc Plasma-Catalyst Process}

The present invention relates to an apparatus and method for treating volatile organic compounds using a gliding arc discharge and a catalyst.

Air pollutants generated by high economic growth and industrial development are causing serious problems that threaten the human body and the natural ecosystem. In particular, volatile organic compounds (VOCs) among air pollutants are emitted from chemical manufacturing processes, automobiles, oil depots, paint manufacturing or building materials. Such volatile organic compounds cause photochemical reactions with nitrogen oxides in the atmosphere, causing ozone or photochemical smog, and are known as substances causing global warming and causing cancer directly in the human body. For this reason, countries have recently enacted regulations on the control of volatile organic compounds to limit their emissions, or to develop technologies to treat them economically and reliably to reduce their emissions.

Among various volatile organic compound treatment technologies, plasma technology has attracted attention. Plasma is an electrically neutral gas composed of excitation electrons, ions, and radicals with high electrical conductivity and influenced by an electromagnetic field, and is also called a fourth state of matter. Active species such as radicals, ions, and excited electrons in the plasma state have high energy and can decompose hardly decomposable substances or chemically stable substances. However, the technology using plasma has high energy consumption rate, various byproducts are generated, and stable power supply.

In order to solve this problem, process technologies combining catalysts with plasma have been studied at home and abroad, and in particular, techniques that combine catalysts with low temperature plasma such as dielectric discharge or corona discharge have been reported. Representatively, by Nunez et al., A process in which a reactor in which a ferroelectric BaTiO ₃ pellet is inserted after a corona discharge reactor has been reported (US Pat. No. 5,236,672). This technique improves the treatment efficiency of harmful gases and recognizes the effect of reducing various by-products, but there is a problem that an additional heating device for activating BaTiO ₃ is required.

In addition, techniques for treating harmful substances by filling various catalysts inside the dielectric discharge reactor have been reported. However, by filling catalysts such as various metal oxides or precious metals in the plasma reaction region, arcs that interfere with stable plasma generation are more likely to occur, and the generated arcs may degrade the performance of the catalysts.

Therefore, there is a need to develop a new plasma catalyst bonding process that can activate the catalyst without additional energy supply and stably generate the plasma without affecting the catalyst.

It is an object of one embodiment of the present invention to provide an apparatus capable of effectively treating volatile organic compounds.

It is an object of another embodiment of the present invention to provide a method for treating volatile organic compounds.

The apparatus for treating volatile organic compounds according to the present invention includes a gliding arc discharge reaction unit including a spring type electrode, a catalyst reaction unit and a power supply unit formed at an outlet of the gliding arc discharge reaction unit.

In addition, the method for treating volatile organic compounds according to the present invention includes (a) introducing a gas containing volatile organic compounds into a reactor in which an arc discharge occurs, thereby decomposing the volatile organic compounds by a plasma formed by the arc discharge. Secondary decomposition process; And (b) a secondary decomposition reaction step of reacting the reaction gas having undergone the step (a) with a metal oxide catalyst to promote an oxidation reaction of the reaction gas.

The apparatus and method for treating volatile organic compounds according to the present invention is excellent in the decomposition efficiency of harmful substances and less reaction by-products by introducing a metal oxide catalyst. In addition, by combining the catalyst layer at the outlet of the plasma reactor, there is an advantage that the plasma can be activated without an additional heat source without affecting the catalyst.

In one embodiment, a processing apparatus for volatile organic compounds (VOCs) includes a gliding arc discharge reaction unit including a spring type electrode, a catalytic reaction unit and a power supply formed at an outlet of the gliding arc discharge reaction unit. An apparatus for treating volatile organic compounds using an arc discharge and a catalyst comprising a part.

"Volatile Organic Compounds" (VOCs) of the present invention refers to liquid or gaseous organic compounds that are easily evaporated into the atmosphere due to high vapor pressure among air pollutants.

In one embodiment, as the reactor in which the gliding arc discharge occurs, a tubular reactor made of a material such as quartz or glass may be used. In addition, a spring-type electrode may be used for the discharger, which may be used without limitation as long as it is a conductive metal material. In another embodiment, the treatment apparatus may use air containing a volatile organic compound as an introduction gas.

In one embodiment, the gliding arc discharge reaction unit, by inducing turbulent flow to the introduced gas, thereby forming a vortex-shaped tornado discharge. Specifically, when the high voltage of the alternating current is applied to the spring type electrode and the other internal electrode of the gliding arc discharge reactor, the discharge form inside the reactor slides along the spring electrode from the nearest point of the two electrodes. Will form. As the introduction gas containing the volatile organic compound passes through the gliding arc discharge region, decomposition reaction of the volatile organic compound occurs primarily by active species such as electrons, ions, radicals and excitation molecules present in the plasma.

After the first decomposition reaction, the resulting adduct and unremoved volatile organic compound components are accelerated by the catalyst bed filled with the activated catalyst, resulting in the decomposition and oxidation reaction, and the product is also converted to less harmful substances. As the catalyst, a metal oxide catalyst may be used, and in one embodiment, the metal oxide catalyst may be one or more metal oxide catalysts selected from the group consisting of Mn, Cr, and Cu. In another embodiment, the metal oxide catalyst may be filled with gamma (γ) -Al ₂ O ₃ as a carrier. More specifically, the metal oxide may be present on the surface of the gamma (γ) -Al ₂ O ₃ carrier as an active material. In addition, the carrier has a size of 1 to 2 mm, and may be in the form of beads or pellets.

The structure of the apparatus for treating volatile organic compounds according to one embodiment of the present invention is shown in FIG. 1.

Referring to FIG. 1, the gliding arc discharge reaction unit 10 and the catalyst reaction unit 20 that generate plasma are combined. The gliding arc discharge reaction unit 10 includes a tubular arc discharge reactor 11 made of quartz, a spring electrode 12 and a ground electrode 13 inside the reactor. When a high voltage is applied through the two electrodes 12 and 13, the arc plasma moves in the reactor 11 from the point where the spring electrode 12 and the ground electrode 13 are adjacent to each other along the spring electrode 12. Is formed. When a gas containing a volatile organic compound is introduced through the gas inlet 14 connected to the front of the processing apparatus, decomposition reaction of the volatile organic compound by active species such as electrons, ions, radicals and excitation molecules existing in the plasma is introduced. This happens primarily. After the first decomposition reaction, the resulting adduct and unremoved volatile organic compound components are led to the catalytic reaction section 20 filled with the activated catalyst. Decomposition and oxidation reactions are promoted by the metal oxide catalyst packed in the catalytic reaction section 20, and the product is also converted into less harmful substances.

The present invention also provides a method for treating volatile organic compounds using an arc discharge and a catalyst.

In one embodiment, the treatment method is (a) a first decomposition reaction process in which a gas containing a volatile organic compound is introduced into a reactor in which an arc discharge occurs, thereby decomposing the volatile organic compound by a plasma formed by the arc discharge. ; And (b) a secondary decomposition reaction step of reacting the reaction gas having undergone the step (a) with a metal oxide catalyst to promote oxidation of the reaction gas.

In one embodiment, the reactor in which the arc discharge occurs comprises a spring type electrode. When a high voltage of alternating current is applied to the spring type electrode and the other ground electrode of the reactor, the discharge form inside the reactor forms an arc plasma as it slides along the spring electrode from the nearest point of the two electrodes.

In another embodiment, the power applied to the reactor of the step (a) may be an AC power source. More specifically, high voltage AC power may be applied to the reactor.

In one embodiment, the metal oxide catalyst of the step (b) may be one or more metal oxides selected from the group consisting of Mn, Cr and Cu. In another embodiment, the catalyst may be filled with gamma (γ) -Al ₂ O ₃ as a carrier. More specifically, the metal oxide may be present on the surface of the gamma (γ) -Al ₂ O ₃ carrier as an active material. In addition, the carrier has a size of 1 to 2 mm, and may be in the form of beads or pellets.

Therefore, the method for treating volatile organic compounds according to the present invention primarily decomposes harmful substances through gliding arc discharge, and secondly decomposes the remaining substances using a metal oxide catalyst. According to the treatment method of the organic compound, the decomposition rate of the volatile organic compound is improved, and the reaction product is converted into a relatively less harmful substance.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples and the like are for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Production Example 1]

Al ₂ O ₃ with a specific surface area of 50 m ² / g and a particle size of 1.5 mm was placed in an electric furnace and fired at 750 ° C. for 6 hours while flowing oxygen into gamma phase Al ₂ O ₃ (γ-Al ₂ O ₃ ). Switched. Then, γ-Al ₂ O ₃ was supported for 1 hour in distilled water in which the precursor CuCl ₂ · 2H ₂ O was dissolved.

After the completion of the support, and dried for 1 hour at 120 ℃, the dried catalyst was put back into the electric furnace and calcined for 6 hours at 550 ℃ in an oxygen atmosphere to prepare a 1% by weight CuO / γ-Al ₂ O ₃ catalyst.

[Production Example 2]

1 wt% MnO ₂ / γ-Al in the same manner as in Preparation Example 1, except that Mn (NO ₃ ) ₂ .6H ₂ O and Cr (NO ₃ ) ₃ .9H ₂ O were used as precursors. ₂ O ₃ , 1 wt% Cr ₂ O ₃ / γ-Al ₂ O ₃ catalyst was prepared.

Example 1

Decomposition effect of VOCs by combining gliding arc discharge and metal oxide catalyst was examined through the following experiment.

The gliding arc discharge reactor used a glass tube with an inner diameter of 20 mm and a length of 150 mm. In addition, as a spring electrode for plasma generation, 1/8 in. Stainless steel tubes were prepared and used with a gap spacing of 10 mm.

In order to generate plasma, the AC power supply used a high voltage AC power supply having a frequency of 20 kHz and a maximum voltage of 10 kV. The voltage and current applied to the reactor were measured using a high voltage / high current probe connected to the oscilloscope. The power consumed in the reactor was obtained by integrating the product of the voltage and current transmitted to the oscilloscope and multiplying by the applied frequency.

Decomposition effects were examined by introducing air containing 370 ppm of benzene, 100 ppm of toluene, and 30 ppm of p-xylene, respectively, into the gliding arc discharge-catalyst coupling system at a flow rate of 10 L per minute. The catalyst used was 1 wt% CuO / γ-Al ₂ O ₃ and filled with 20 g. Plasma conditions, the average applied voltage is 1.4 kV at a frequency of 20 kHz, and the decomposition rate, selectivity and power consumption of each product (CO + CO ₂ ) were measured. The measured results are shown in Table 1 below.

Material to be processed % Decomposition CO + CO ₂ (%) Power Consumption (W) Benzene 370ppm 79.3 99.7 142 Toluene 100ppm 87.0 98.5 140 30 ppm p-xylene 100 99.8 138

Referring to Table 1, the decomposition rate of benzene was 79.3%, the decomposition rate of toluene was 87.0%, and the decomposition rate of p-xylene was 100%. In addition, the products of [CO + CO ₂ ] were 99.7, 98.5 and 99.8% and consumed 142, 140, 138 W of power.

Comparative Example 1

Except for the absence of a catalyst, the same method as in Example 1 was applied to the gliding arc discharge reactor by applying an average voltage of 1.4 kV at a frequency of 20 kHz to determine the respective decomposition rate and the product (CO + CO ₂ ). The selectivity of and the energy consumed were measured. The measured results are shown in Table 2 below.

Material to be processed % Decomposition CO + CO ₂ (%) Power Consumption (W) Benzene 370ppm 69.9 82.5 159 Toluene 100ppm 76.5 85.4 145 30 ppm p-xylene 93.2 99.5 155

Referring to Table 2, the decomposition rate of benzene was 69.9%, the decomposition rate of toluene was 76.5%, and the decomposition rate of p-xylene was 93.2%. In addition, the products of [CO + CO ₂ ] were 82.5%, 85.4%, 99.5%, at which the power of 159W, 145W, 155W was used.

Compared with the results of Example 1, when the catalyst was introduced into the plasma, the power consumption was about 10 W less than the plasma treatment alone, and the decomposition rate was 10% benzene, 11.5% toluene, and p-xylene 6.8. Improved by%.

In addition, the results of Example 1 and Comparative Example 1 are collectively shown in FIG. 2. In FIG. 2, the x axis represents a substance to be treated (benzene, toluene, p-xylene), and the y axis represents a decomposition rate of the substance to be treated and selectivity of [CO + CO ₂ ].

1 is a schematic diagram schematically showing an apparatus for treating volatile organic compounds according to an embodiment of the present invention;

Figure 2 is a graph analyzing the difference between the decomposition rate of the volatile organic compounds and the selectivity of CO + CO _{2 with} or without the introduction of a metal oxide catalyst.

[Explanation of main parts of drawing]

10: arc discharge reactor, 11: arc discharge reactor

12: spring electrode, 13: ground electrode

14: gas inlet, 20: catalytic reaction section

Claims (11)

An apparatus for treating volatile organic compounds using an arc discharge and a catalyst comprising a gliding arc discharge reaction unit including a spring type electrode, a catalyst reaction unit and a power supply unit formed at an outlet of the gliding arc discharge reaction unit. The method of claim 1, The gliding arc discharge reaction unit, by inducing turbulent flow to the introduced gas, to form a vortex-shaped tornado-type discharge, characterized in that the apparatus for treating volatile organic compounds using an arc discharge and a catalyst. The method of claim 1, The power supply unit is a device for treating volatile organic compounds using an arc discharge and a catalyst, characterized in that for supplying AC power to the gliding arc discharge reaction unit. The method of claim 1, The catalytic reaction unit, the arc discharge and the apparatus for treating volatile organic compounds using a catalyst, characterized in that it comprises an oxide of a metal selected from the group consisting of Mn, Cr and Cu. The method of claim 4, wherein The catalytic reaction unit, the apparatus for treating volatile organic compounds using an arc discharge and a catalyst, characterized in that further comprises a gamma (γ) -Al ₂ O ₃ carrier. The method of claim 5, An apparatus for treating volatile organic compounds using an arc discharge and a catalyst, wherein the carrier has a size of 1 to 2 mm and has a bead or pellet shape. (a) a primary decomposition reaction step of decomposing the volatile organic compound by a plasma formed by the arc discharge by introducing a gas containing the volatile organic compound into the reactor in which the arc discharge occurs; And (b) A method of treating volatile organic compounds using an arc discharge and a catalyst, comprising a secondary decomposition reaction step of reacting the reaction gas passed through the step (a) with a metal oxide catalyst to promote oxidation of the reaction gas. The method of claim 7, wherein The reactor in which the arc discharge occurs comprises a spring-type electrode, characterized in that the arc discharge and the method of treating volatile organic compounds using a catalyst. The method of claim 7, wherein The method for treating volatile organic compounds using an arc discharge and a catalyst, characterized in that the power source applied to the reactor of the step (a) is an alternating current source. The method of claim 7, wherein The metal oxide catalyst of the step (b) is at least one metal oxide selected from the group consisting of Mn, Cr and Cu, the arc discharge and the method of treating a volatile organic compound using a catalyst. The method of claim 10, The metal oxide catalyst, gamma (γ) -Al ₂ O _{3 The} method of treating the volatile organic compounds using an arc discharge and the catalyst, characterized in that the carrier.

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