KR20060100828A - Apparatus for the treatment of volatile organic compounds - Google Patents

Abstract

The present invention relates to a treatment apparatus for a volatile organic compound, comprising: A) a main body having a volatile organic compound gas inlet and a treated gas outlet; B) a photocatalyst layer and a plasma generating means are mounted in a tubular reactor having a gas inlet and an outlet, and the gas inlet is mounted in the body so as to communicate with the volatile organic compound gas inlet of the body; And C) using a treatment apparatus of the present invention positioned near the plasma-photocatalytic reactor in the body to irradiate the photocatalyst layer with ultraviolet light, to continuously and efficiently react high concentrations and large amounts of volatile organic compounds while suppressing side reactions. Can be processed.

Description

Processing device for volatile organic compounds {APPARATUS FOR THE TREATMENT OF VOLATILE ORGANIC COMPOUNDS}

FIG. 1A is a schematic diagram of a volatile organic compound processing apparatus according to one embodiment of the present invention, FIG. 1B is a schematic diagram showing a plasma-photocatalytic reactor located inside the processing apparatus together with a gas inlet and an outlet;

2 is an overall schematic diagram of a volatile organic compound processing apparatus used in Example 1,

Figure 3 shows a graph of the conversion (%) change over time in the benzene treatment according to Example 1, and Comparative Examples 1 and 2,

Figure 4 shows the distribution (mol%) of the reaction product obtained 20 minutes after showing the maximum conversion in the benzene treatment according to Example 1, and Comparative Examples 1 and 2,

5 is a result of GC (gas chromatography) analysis of the reaction product obtained when the plasma production conditions (energy density) in Comparative Example 1,

FIG. 6 is a graph illustrating conversion rate (%) change with time when the amount of the photocatalyst supported in Example 1 is changed.

<Description of the symbols for the main parts of the drawings>

10: air tank

12: mass flow controller (MFC)

14 volatile organic compound injector 16 valve

18: H ₂ O injector 20: mixing tank

22: power supply 24: flow rate meter

26: sampling valve / water gauge 28: water trap

30 gas chromatography (GC) 100 processing apparatus

101: gas inlet 102: gas outlet

200: ultraviolet lamp 300: plasma-catalyst reactor

310: metal wire 320: insulator

330 body 340 metal mesh

350: photocatalyst layer 360: gas inlet

370: gas outlet

The present invention relates to an apparatus capable of efficiently and continuously treating volatile organic compounds using a dielectric discharge plasma as a light source for a photocatalytic reaction.

Conventionally, a plasma or a catalyst is mainly used by corona discharge to purify harmful exhaust gas from an engine or an incinerator.

The exhaust gas purification apparatus using plasma by corona discharge oxidizes or reduces harmful substances (nitrogen oxides, sulfur oxides, volatile organic compounds, dioxins, etc.) contained in the exhaust gas by plasma chemical reaction. Typical exhaust gas purifiers include a linear wire electrode-to-cylinder type with a corona discharge electrode, and a needle source-to-flat with a corona discharge electrode as a bed. plate) and the like are typically used.

In the purification method using a catalyst, a general catalyst does not need a separate light source, but requires a separate reaction activity condition such as a high temperature. In the case of a photocatalyst, a light source having a specific wavelength (ultraviolet region, i.e., near 400 nm) For example, TiO ₂ is irradiated to free pollutants with free radicals generated during photocatalytic excitation. In this case, an ultraviolet lamp, which is an ultraviolet region photogenerator, has been mainly used.

However, there is a problem in that a large amount of hydrocarbon by-products are generated by an undesired side reaction when purifying toxic substances by using the plasma by corona discharge as described above. It is difficult and has the problem that the energy efficiency of the existing UV lamp light source is as low as 20%. In addition, the use of the purification apparatus using these individually has not only limited the purification treatment, but also the efficiency is not so good in terms of energy input.

Therefore, in recent years, a mixture of a plasma and a catalyst or photocatalyst mixed harmful gas purification device has been developed to reduce the energy consumption and improve the processing performance (Korean Patent Publication No. 2001-105140). Since the life cycle of the produced species (various ions, radicals) is usually several microseconds or less, the generated species reacts with the catalyst within this short time to exhibit high gas purification efficiency. The wealth must be effectively combined.

However, the hybrid purifiers known so far still have limitations on the noxious gas treatment efficiency due to the inefficient structure of the plasma generating unit and the catalytic reaction unit or the inefficient coupling between the two.

It is therefore an object of the present invention to provide an apparatus capable of efficiently and continuously treating volatile organic compounds that are harmful gases while suppressing side reactions.

In the present invention to achieve the above object,

A) a main body having a volatile organic compound gas inlet and a process gas outlet;

B) a plasma-photocatalytic reactor mounted in the body such that the photocatalyst layer and the plasma generating means are mounted in a tubular reactor having a gas inlet and an outlet, the gas inlet being in communication with the volatile organic compound gas inlet of the body; And

C) It provides a volatile organic compound processing apparatus comprising an ultraviolet lamp positioned in the main body adjacent to the plasma-photocatalytic reactor to irradiate ultraviolet light to the photocatalyst layer.

The present invention also provides a method for treating volatile organic compounds using the treatment apparatus.

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

One example of the treatment apparatus of the present invention is shown in FIG. 1A and one example of a plasma-photocatalyst reactor having a gas inlet and an outlet located inside the treatment apparatus. The plasma-photocatalyst complex processing apparatus of the present invention is characterized by using a dielectric barrier discharge (DBD) plasma as a light source for the photocatalytic reaction together with an ultraviolet lamp.

Referring to FIG. 1A, a processing apparatus 100 in which a plasma-photocatalyst complex reaction occurs according to the present invention includes a main body having a volatile organic compound gas inlet 101 and a processing gas outlet 102, and a plasma-photocatalyst inside the main body. Reactor 300 and ultraviolet lamp 200.

In addition, referring to FIG. 1B, the plasma-photocatalytic reactor 300 according to the present invention mounted in the processing apparatus 100 main body communicates with the gas inlet 360 and the gas communicating with the volatile organic compound gas inlet 101 of the main body. It has a tubular reactor body 330 with an outlet 370 and includes a photocatalyst layer 350 and plasma generating means therein. As the plasma generating means, one end is connected to a power source and a metal wire 310 positioned to pass through the photocatalyst layer 350 is suitable. Preferably, the metal wire 310 penetrates through the center of the photocatalyst layer 350, and the opposite end of the gas outlet 370 of the metal wire 310 protrudes out of the plasma-photocatalytic reactor 300 to be connected to a power source. In addition, the plasma-photocatalytic reactor 300 includes a metal mesh 340 surrounding the photocatalyst layer 350 in the body 330 for efficient generation of plasma, and the body protruding outward from the metal wire 310. 330 includes an insulator 340 at the distal end.

The ultraviolet lamp 200 mounted in the main body of the processing apparatus 100 is positioned adjacent to the plasma-photocatalytic reactor 300 to irradiate the photocatalyst layer 350 with ultraviolet rays, in order to facilitate replacement of the lamp. The upper and lower covers of the device 100 may be manufactured in the form of screws to mount the ultraviolet lamp 200 inside the covers.

The plasma-photocatalytic reactor 300 and the ultraviolet lamp 200 may each be mounted in one or more bodies of the processing apparatus 100.

According to the present invention, the volatile organic compound gas supplied from the volatile organic compound gas inlet 101 is introduced into the plasma-photocatalytic reactor 300 through the gas inlet 360 to pass through the photocatalytic layer 350 and the plasma-catalyst After being primarily purified by the combined reaction, the gas outlet 370 is first purified after passing through an ultraviolet lamp 200 located adjacent to the plasma-photocatalytic reactor 300 and then the process gas outlet 102. Is discharged through). According to the plasma-photocatalyst complex reaction, electrons having kinetic energy significantly higher than ordinary ions or molecules are generated by electric discharge, and they dissociate molecules by colliding with surrounding contaminants to make them highly reactive. To create radicals or secondary electrons. All these reaction mechanisms are possible at room temperature.

The photocatalyst layer 350 filled in the metal mesh 340 surrounding the inner wall of the body of the plasma-photocatalytic reactor 300 may be coated with, for example, glass beads or TiO ₂ coated with a mixture of TiO ₂ and SiO ₂ (binder). Γ-Al ₂ O ₃ , and the amount of the photocatalyst can be appropriately adjusted as necessary.

The tubular reactor, ie the body 330 of the plasma-photocatalytic reactor 300 may be made of quartz. The metal wire 310 and the metal mesh 340 may be any conductive metal, but most commonly wire and wire mesh may be used, and the insulator 320 may be any insulating material, but most commonly teflon may be used. .

An AC high voltage amplifier is suitable as an external power source connected to the processing apparatus 100 through the metal wire 310, and an energy density (SIE) in the range of 140 to 680 J / L is applied to the plasma photocatalytic reactor 300 using the power source. It is desirable to provide specific input energy.

As described above, the present invention utilizes the plasma-photocatalytic complex processing apparatus of the present invention, which uses a dielectric discharge plasma as a light source for the photocatalytic reaction together with ultraviolet rays, thereby enhancing the efficiency of the photocatalytic reaction and suppressing side reactions of the plasma reaction, thereby increasing the concentration. And a method capable of efficiently and efficiently treating a large amount of volatile organic compounds. According to the apparatus and method of this invention, the synergy effect of a photocatalytic reaction and a plasma reaction can also be acquired.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Example 1

The benzene gas discharged from the domestic coating process was treated with the system shown in FIG. 2 using the treatment apparatus as shown in FIGS. 1A and 1B.

In FIG. 1, volatile organic compounds (benzene gas) exited the injector 14 and entered the processing apparatus 100 with the flow rate controlled by the mass flow controller (MFC) 12 and the valve 16. After treatment by the plasma-photocatalyst complex reaction in the processing apparatus 100, it was transferred to the gas chromatography 30 for component analysis. At this time, the H ₂ O in a mixing tank (20) using a H ₂ O injector 18 to increase the amount of the OH radical to activate the reaction was mixed at a weight ratio of the benzene gas and 1: 10, the mixture 200 Flow into the treatment unit 100 at a flow rate of ml / min (pure benzene concentration: about 100 ppm level). The connecting pipe through which benzene gas passes was kept above 30 ° C. to prevent condensation of benzene gas.

Processing apparatus 100 inside the plasma-were seated side by side the two photocatalytic reactor 300, plasma-photocatalyst layer 350 of a photocatalytic reactor 300 is TiO ₂ photocatalyst as a coating γ-Al ₂ O ₃ TiO ₂ The loading amount of was 1.5% by weight based on the total weight of the filler, the metal wire 310 is a wire of 1 mm diameter, the metal mesh 340 is a wire mesh, the reactor body 330 is quartz, and the insulator 320 is Teflon Was done. As the UV lamp 200, three 28W UV-A lamps were mounted on each of the upper and lower covers of the processing apparatus 100. The specific input energy (SIE) in the plasma-photocatalytic reactor 300 was set to 140 J / L using the power supply 22 as an AC high voltage amplifier. The treatment of benzene gas was carried out for 90 minutes, and the conversion of benzene gas was measured through component analysis in gas chromatography.

Comparative Example 1

After treating the benzene gas for 90 minutes under the conditions similar to those of Example 1 (benzene gas flow rate: 200 ml / min, energy density: 140 J / L) using a conventional volatile organic compound treatment apparatus by plasma, the gas The conversion of benzene gas was measured through component analysis in chromatography.

Comparative Example 2

Benzene gas under conditions similar to Example 1 (benzene gas flow rate: 200 mL / min, 1.5 wt% of TiO ₂ coated γ-Al ₂ O ₃ coated) using a conventional volatile organic compound treatment device by a photocatalyst After 90 minutes of treatment, the conversion of benzene gas was measured by component analysis in gas chromatography.

In the benzene treatment according to Example 1 and Comparative Examples 1 and 2, a graph showing the change in conversion rate (%) with time is shown in FIG. 3, and the distribution (mole%) of the reaction product obtained 20 minutes after the maximum conversion rate is shown. 4 is shown respectively.

From FIG. 3, in Example 1 using the apparatus of the present invention, the conversion rate of benzene reached up to 50%, and increased by about 10% compared to Comparative Example 1 using only plasma, and Comparative Example 2 using only photocatalyst compared to these. It can be seen that the conversion rate is significantly lower.

In addition, from FIG. 4, Example 1 shows that the amount of the desired treatment product in the form of a fully oxidized form, such as CO ₂ , is generated near 50 mol% on a carbon balance basis and very small by-products such as phenol are produced. Comparative Example 1 can be seen that a relatively large amount of by-products are generated, Comparative Example 2 is that most of the benzene does not participate in the photocatalytic reaction and is discharged as it is.

Reference Example 1 Change in Energy Density in Comparative Example 1

In Comparative Example 1, when the energy density, which is a plasma generation condition, was changed to 140, 300, and 680 J / L, the reaction product obtained after 20 minutes was analyzed by gas chromatography, and the results are shown in FIG. 5. It was.

5, in any case, it can be seen that a large amount of hydrocarbon by-products due to various side reactions are produced as a final product.

Reference Example 2: Change in the amount of photocatalyst loading in Example 1

In Example 1, when the loading amount of the photocatalyst was changed to 0, 1.5, 3, and 5% by weight of the total weight of the filler, the change in conversion rate (%) was observed for each time, and a graph of the conversion rate change is shown in FIG. 6.

In FIG. 6, it can be seen that the difference in benzene decomposition activity is not large according to the amount of the photocatalyst supported, which shows that the amount of the photocatalyst participating in the reaction is relatively constant.

As described above, according to the plasma-photocatalytic complex processing apparatus of the present invention using a dielectric discharge plasma as a light source for the photocatalytic reaction with ultraviolet rays, it is possible to improve the efficiency of the photocatalytic reaction and to suppress side reactions of the plasma reaction, thereby increasing the concentration and the high volatility. The organic compound can be efficiently processed continuously, and synergistic effects of the photocatalytic reaction and the plasma reaction can also be obtained.

Claims (7)

A) a main body having a volatile organic compound gas inlet and a process gas outlet; B) a photocatalyst layer and a plasma generating means are mounted in a tubular reactor having a gas inlet and an outlet, and the gas inlet is mounted in the body so as to communicate with the volatile organic compound gas inlet of the body; And C) an ultraviolet lamp positioned in the body adjacent to the plasma-photocatalytic reactor and irradiating ultraviolet light to the photocatalyst layer. The method of claim 1, And a plasma generating means of the plasma-photocatalytic reactor, wherein one end is a metal wire connected to a power source and positioned to pass through the photocatalyst layer. The method of claim 1, The photocatalytic layer of the plasma-catalyst reactor is characterized in that the glass bead coated with a mixture of TiO ₂ and SiO ₂ or γ-Al ₂ O ₃ coated with TiO ₂ , volatile organic compound processing apparatus. The method of claim 1, A device for treating volatile organic compounds, characterized in that the photocatalyst layer inside the plasma-catalyst reactor is surrounded by a metal network. The method of claim 1, The tubular reactor of the plasma-photocatalytic reactor is characterized in that made of quartz, volatile organic compound processing apparatus. The method of claim 2, An apparatus for treating volatile organic compounds, characterized in that an energy density of 140 to 680 J / L is provided to the plasma-photocatalytic reactor by a power source. The volatile organic compound is supplied to the volatile organic compound gas inlet of the apparatus according to any one of claims 1 to 6 to be introduced into the plasma-photocatalytic reactor, and the gas discharged therefrom after the primary purification treatment. A volatile organic compound treatment method comprising the secondary purification treatment with a lamp.

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