KR20010070547A - Apparatus for removing volatile organic compounds by high voltage and high frequency plasma. - Google Patents

Abstract

PURPOSE: A removal equipment of volatile organic compounds (VOCs) using high voltage and high frequency plasma is provided, which can decompose molecules of volatile organic compounds (VOCs), oxygen and water by forming electron-holes on the surface of an oxidative semiconductor and by electrically exciting the molecules, so that the system can treat VOC of large amount and high concentration rapidly. CONSTITUTION: The system comprises the followings: (i) to high voltage plasma parts of an oxidative semiconductor catalytic electrode and a titanium dioxide semiconductor catalytic electrode, apply pulse 12kV and alternating current 30kV; and (ii) to high frequency plasma parts of the above electrodes, apply alternating current of +20 kV/+10kV/-20kV and 200kHz, 450V for decomposing volatile organic compounds by electrolysis method.

Description

Apparatus for removing volatile organic compounds by high voltage and high frequency plasma.

The present invention relates to a high voltage and high frequency plasma apparatus for decomposing and removing volatile organic compounds prepared by an oxidative semiconductor catalyst electrode, and saves energy by applying an electrochemical decomposition method to the removal of volatile organic compounds generated by industrial activities. It is to provide a device that can reduce the cost, increase the efficiency and light weight, simplify and large capacity, high concentration and rapid treatment, but do not generate secondary pollutants.

Removal of volatile organic compounds from pollutant sources include adsorption, incineration, cooling and condensation. The adsorption method is a method of adsorption, recovery or removal using an adsorbent such as activated carbon, which can remove volatile organic compounds having a lower explosion limit of 25% or more, and the installation cost is low, but ketones, aldehydes, esters, styrenes, etc. Substances tend to degrade the adsorption function by causing polymerization on the surface of activated carbon to block micropores of activated carbon, and treatment of wastes generated through adsorption is a problem. In addition, the process capacity is lower than the conventional volatile organic compound treatment method, which is not suitable for a high flow rate process. Incineration has direct combustion method and catalytic combustion method, and it has the advantage of dealing with a large amount of volatile organics, but it is uneconomical in case of heavy load fluctuation, low concentration and low flow rate. As a result, it is difficult to expand equipment, and secondary air pollutants such as nitrogen oxides, carbon dioxide, and soot may be generated due to combustion. And a lot of maintenance costs, such as fuel costs required for combustion. The biological treatment method mainly uses aerobic microorganisms, but the maintenance cost is low. However, the load of organic compounds required for the activity of the microorganisms is severe, or it is difficult to maintain compatibility with the microorganisms and the carrier for a certain temperature range or PH. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and is an enclosed reaction tank in which an oxidative semiconductor catalyst and a high voltage alternating current, direct current and high frequency alternating current are used as energy sources to electrolyze volatile organic compounds by electrode reaction. Its purpose is to be able to process large capacity and high concentration quickly, and to make the structure light, simple and energy-saving.

Means to Solve the Problem

The basic structure of the present invention is composed of a high voltage plasma unit and a high frequency plasma unit, the high voltage plasma unit is supplied with a power of pulse 12 ㎸ and AC 30 ,, high frequency plasma unit DC +20 ㎸ / +10 ㎸ / -20 ㎸ and frequency An AC power supply of 200 kV and 450 V is supplied.

Accordingly, in terms of electrochemical decomposition, the electromagnetic coupling of the incoming volatile organic compounds enters the high frequency plasma part in an unstable state that is electrically excited from the high voltage plasma part.

If you exhibit this effect

CxHyOz + high voltage → CxHyOz ^*

H ₂ O + high voltage → H ₂ O ^*

O ₂ + high voltage → O ₂ ^*

(* Indicates an electrically excited state)

Thus CxHyOz ^* → CO ₂ + H ₂ O

As a result, the current doubling effect acts to speed up the reaction.

In addition, in terms of semiconductor engineering, the electrodes with high voltage plasma 12 volts and alternating current 30 ㎸, high frequency plasma portions with +10 ㎸ and +20 ㎸ high voltage are composed of oxidative semiconductor catalyst electrodes and -20 ㎸ negative voltage. Is a titanium dioxide semiconductor catalyst electrode, and a high frequency plasma portion to which a 200 kW, 450 V AC power is applied is made of an oxidative semiconductor catalyst electrode. That is, it is composed of p-n-p type by semiconductor engineering analysis, so that when positive + /-/ + voltage is applied, it accelerates positive charges and increases oxidative decomposition reaction of volatile organic compounds.

In terms of catalysis, the oxidative semiconductor catalyst is an anatase type titanium dioxide prepared from titanium alkoxide, which is the reaction center of the catalyst. Electrons are accelerated according to the waveform of the electron-hole separation. In other words, the oxidation of the holes occurs on the surface of the oxidative semiconductor by the constant voltage of the AC power source, and the reduction of electrons occurs by the negative voltage.

If this catalytic reaction is represented by the reaction formula

a) Main reaction at constant voltage

H ₂ O ^* + h ⁺ → 2H ⁺ + ½O ₂

H ₂ O ^* + h ⁺ → H ⁺ + OH (OH radical)

OH + h ⁺ → HO

2HO → (0) + H ₂ O

h ⁺ → h ⁺ trap (oxidizes directly to the holes trapped on the surface)

a) side reactions at negative voltage

2H ^{+ +} e ^- → H ₂

Surface adsorption _{^{O 2 * + e - → ·}} O 2 -

_{^{· O 2 - + H + →}} HO 2 · (peroxo radical)

The above catalytic reaction occurs.

Thus CxHyOz ^* → CO ₂ + H ₂ O

↑

Catalysis (OH + h ⁺ trap)

The reaction is done quickly.

In terms of the electromagnetic field, + 20kV / + 10kV / -20kV becomes a uniform phase stopped by a DC power supply, and the 200kHz and 450V of the high frequency plasma part change the electric field and magnetic field with time, that is, the speed of the electron changes. AC power, that is, it is formed as a moving field. A relative electromagnetic field is formed between the stationary field and the moving field, and a displacement current, a charge that changes with time, flows between the anodes of the AC power source.

Since the displacement current is very low in energy consumption, the biggest feature of the present invention can be an energy-saving device with low consumption of electrical energy required for operation.

<< Example >>

<Oxidative semiconductor catalyst electrode production>

Titanium alkoxide is mixed with two solutions with a 5 wt% aqueous sulfuric acid solution / alkoxide molar ratio of 50, followed by stirring for 2-3 hours to cause a hydrolysis reaction. Based on 100 g of the obtained orthotitanic acid, 20 to 30 g of a 4 wt% lithium hydroxide aqueous solution, 1.5 to 3.0 g of methanol, and 5 to 15 g of 1 wt% chloroplatinic acid are mixed and stirred for 1 to 5 hours under high pressure mercury. . Then, 5 to 10 g of bismuth oxide was mixed and stirred for 1 to 5 hours, and then 5 to 40 g of silver iodide or potassium iodide dissolved in 20% by weight in 10% aqueous ammonia was added, and vanadium pentoxide, tungsten trioxide, and molybdenum trioxide were added thereto. 1 to 5 g of each, 5 to 25 g of manganese dioxide, 10 to 40 g of copper oxide, and 1 to 2 g of cobalt oxide were added and finally stirred for 2 to 8 hours.

The dispersion-finished semiconductor composition is coated on a stainless mesh or stainless fiber mat, and then fired at 350 to 500 ° C. for 6 to 12 hours to obtain a final oxidative semiconductor catalyst electrode.

< Titanium Dioxide Semiconductor Catalyst Electrode Fabrication>

Titanium alkoxide is mixed with two solutions with a 5 wt% aqueous sulfuric acid solution / alkoxide molar ratio of 50, followed by stirring for 2-3 hours to cause a hydrolysis reaction.

20-40 g of aqueous 4 wt% aqueous lithium hydroxide solution and 10 to 20 g of lanthanum oxide are mixed and stirred for 2 to 4 hours, based on 100 g of oligo titanic acid obtained therefrom. Thereafter, 10 to 40 g of silver iodide or potassium iodide dissolved in 20% by weight in 10% ammonia water is added, 0.5 to 2.0 g of carbon is mixed and finally stirred for 2 to 8 hours. After the dispersion is completed, the semiconductor composition is coated on a stainless mesh or stainless fiber mat, and then calcined at 350 to 500 ° C. for 6 to 12 hours to obtain a final titanium dioxide semiconductor catalyst electrode.

1 is a basic diagram of a high voltage plasma unit

2 is a basic diagram of a high frequency plasma unit

<Description of the code | symbol about the principal part of drawing>

1-oxidative semiconductor catalyst electrode

2-Titanium Dioxide Semiconductor Catalytic Electrode

.

As described above, the present invention forms electron-holes on the surface of an oxidative semiconductor by electrical energy and electrically excites and decomposes molecules of volatile organic compounds, oxygen, and moisture due to high fields, thereby rapidly processing large capacity and high concentration. In addition, the energy efficiency can be maximized by reducing the installation area and designing an energy-saving type with low maintenance cost.

Claims (3)

In the method for producing an oxidative semiconductor catalyst electrode, having the following structural formula, BT-MO-X Here, B is bismuth, T is titanium dioxide, and MO is an oxide metal, which corresponds to vanadium pentoxide, tungsten trioxide, molybdenum trioxide, manganese dioxide, copper oxide, and cobalt oxide, and X is manufactured based on iodide or potassium iodide. An oxidative semiconductor catalytic electrode In the method for producing a titanium dioxide semiconductor catalyst electrode, LaT-X having the following structural formula Where La is lanthanum, T is titanium dioxide, and X is iodide or potassium iodide. Volatile organic compounds were applied by the electrolysis method by applying pulse 12kV and AC 30kV, high frequency plasma part + 20kV / + 10kV / -20kV and high frequency 200kHz, 450V to the high voltage plasma part of the oxidizing semiconductor catalyst electrode and the titanium dioxide semiconductor catalyst electrode. Device to disassemble and remove