KR20100127146A - Method for preparing photocatalyst, photocatalyst prepared by using the same and process for decomposing volatile organic composite using the same - Google Patents

Abstract

PURPOSE: A producing method of an optical catalyst, the optical catalyst, a reactor using thereof, an optical decomposition apparatus, and a decomposition method of a volatile organic material are provided to easily produce the optical catalyst. CONSTITUTION: A producing method of an optical catalyst comprises the following steps: reacting a mixture containing a solvent, titanium alkoxide, and activated carbon; and combusting the activated carbon by heat-treating the outcome from the previous step. The solvent is selected from the group consisting of water, alcohol, and cellosolve. The average particle diameter of the activated carbon is 0.1~10 micrometers. The heat-treating process is performed in 400~700deg C.

Description

Method for preparing photocatalyst, photocatalyst prepared by using the same and process for decomposing volatile organic composite using the same}

The present invention relates to a method for producing a photocatalyst, a photocatalyst prepared by the method and a method for decomposing volatile organics using the same.

Odor-causing substances are commonly referred to as volatile organic substances (VOC), and are used for air degassing, hazardous waste incineration facilities, chemical product manufacturing, textile product manufacturing, fertilizer manufacturing facilities, biological wastewater treatment facilities, carbon regeneration facilities, urban landfill sites, and dry Many occur throughout industries such as cleaning facilities, degreasing facilities, freon applications and the food industry.

In addition, volatile organics such as toluene, acetone, and methyl ethyl ketone (MEK) discharged from the plant are highly odorous to cause discomfort even at low concentrations. Etc.

With the expansion of residential areas, the gap between houses and factories is decreasing, and the necessity of managing odor-causing substances is increasing.Efficient removal of volatile organic matters inevitably released during the operation phase is emerging as an important issue in terms of reducing environmental burden. In particular, human hazards caused by various VOCs generated from interior finishing materials, such as sick house syndrome, are becoming a serious social problem. Therefore, a solution is required.

Currently used methods for removing volatile organics include adsorption, combustion, air dilution and biofiltering.

Adsorption methods are economically inexpensive and simple to use, but they are frequently used. However, the efficiency of adsorbents is low within a short period of time, which makes them difficult to use for a long time and requires costly exchange of adsorbents or desorption processes regularly. Although the process is simple and easy to manage, there is a concern that harmful secondary by-products may occur due to rising power costs and combustion.

In addition, the air dilution method is easy to use, but if applied in the long-term there is a concern that it may cause serious environmental problems, the biofilter method has a problem that the target material is limited and not suitable for high concentrations of harmful substances or high-speed treatment.

In order to solve the above problems, organic material removal technologies using photocatalysts having organic material resolution have been developed.

Korean Patent No. 0324541 discloses a method for removing VOCs such as trichloroethylene (TCE) using a tube type photochemical reaction device filled with a photocatalyst-coated filler.

In addition, the Republic of Korea Patent No. 0469005 discloses a method for enhancing the photolysis efficiency by attaching a reflector to the inner wall of the photoreactor in removing the VOC using a photoreactor coated with a photocatalyst sol coated on a metal plate Doing.

However, the above methods are disadvantageous in that they are not a technique using an excellent photodegradation efficiency of the photocatalyst itself in that it is a technique of removing organic substances such as VOC by coating a photocatalyst such as titanium dioxide, which has been conventionally used, on a packed layer or a carrier.

In addition, Korean Patent No. 0714849 discloses a method of removing VOC by fixing titanium dioxide in a reactor using silane, but in the case of using silane as a binder for fixing titanium dioxide, the adhesive strength is excellent, There is a fear that the silane is transformed into a material having a double bond as received, thereby reducing the photolysis efficiency of titanium dioxide.

The present invention was created to solve the above-mentioned problems, and an object of the present invention is to prepare a photocatalyst that provides a porous photocatalyst having pores formed by adding activated carbon when synthesizing a titanium dioxide catalyst and then burning the activated carbon in a heat treatment process. It is to provide a photocatalyst prepared according to the method and the manufacturing method having a specific surface area significantly larger than the conventional photocatalyst.

In addition, another object of the present invention is to provide a reactor and a photodegradation apparatus that can exhibit more efficient and excellent photodegradation efficiency by including the photocatalyst, and provides a method of decomposing volatile organic substances by removing harmful volatile organic substances using the photocatalyst. It is.

The present invention as a means for solving the above problems, a first step of reacting a mixture comprising a solvent, titanium alkoxide and activated carbon; And a second step of burning the activated carbon by heat-treating the reactants obtained in the first step.

In addition, the present invention provides a photocatalyst prepared by the manufacturing method according to the present invention as another means for solving the above problems.

In addition, the present invention is another means for solving the above problems, a support; And a photocatalyst layer formed on the support and containing the photocatalyst according to the present invention.

In addition, the present invention is another means for solving the above problems, the reactor according to the present invention; And a mixing part supplying a mixture containing volatile organic matter and water to the reactor.

In another aspect, the present invention provides a method for decomposing volatile organic matter comprising the step of supplying a mixture containing water and volatile organic matter to the reactor according to the present invention.

The method for preparing a photocatalyst according to the present invention may provide a porous photocatalyst in which fine pores are formed by adding activated carbon to react with the synthesis of titanium dioxide particles and then burning the mixed activated carbon through a heat treatment process. The obtained photocatalyst can have a superior photo resolution by having a remarkably large specific surface area.

In addition, by using the photocatalyst it can be provided a reactor having excellent photolysis efficiency and a photolysis device including the reactor, by using this can provide a decomposition method of volatile organic matter to remove volatile organic matter more efficiently. .

The present invention comprises a first step of reacting a mixture comprising a solvent, titanium alkoxide and activated carbon; And a second step of burning the activated carbon by heat-treating the reactants obtained in the first step.

Hereinafter, a method of manufacturing the photocatalyst according to the present invention will be described in more detail.

As described above, the method for preparing a photocatalyst according to the present invention comprises a first step of reacting a mixture comprising a solvent, titanium alkoxide and activated carbon; And a second step of burning the activated carbon by heat-treating the reactants obtained in the first step.

Here, the solvent is not particularly limited, but one or more selected from water, alcohol or cellosolve may be used, and the alcohol may be methanol, ethanol, propanol, butanol, isopropanol or diacetyl alcohol, and the like. As the solve, methyl cellosolve, ethyl cellosolve, butyl cellosolve or cellosolve acetate may be used.

In addition, the titanium alkoxide may be a compound represented by the following Chemical Formula 1.

Ti (OR ₂ ) ₄

In Formula 1, R ₂ represents an alkyl group having 1 to 6 carbon atoms.

Although the type of the titanium alkoxide is not particularly limited, for example, titanium tetrapropoxide (Titanium (IV) propoxide), titanium tetraisopropoxide (Titanium (IV) isopropoxide) or titanium tetradiisopropoxide (Titanium (IV) diisopropoxide), titanium tetrabutoxide (Titanium (IV) butoxide), titanium tetraethoxide (Titanium (IV) ethooxide) and titanium tetramethoxide (Titanium (IV) methoopoxide) The above can be used.

On the other hand, the activated carbon is contained in a mixture with a solvent and a titanium alkoxide in the synthesis of titanium dioxide, the reaction is carried out, is discharged as carbon dioxide by burning through a heat treatment process, at the same time to form fine pores in the titanium dioxide particles It serves to increase the specific surface area of titanium.

The activated carbon is not particularly limited in kind, and activated carbon commonly used in the art may be used, for example, spherical activated carbon may be used, and specifically, to form micropores in titanium dioxide. Activated carbon may be used in which water is sufficiently removed and no agglomeration occurs.

In addition, the activated carbon may be one that has been aged at a high temperature of 100 ° C. or more for at least 1 hour or subjected to physical treatment such as plasma treatment. More specifically, in order to improve the dispersing effect, a silane-based surface treatment agent is applied to the surface of the active agent. Doped can be used to increase the dispersion effect.

Although the average particle diameter of the said activated carbon is not specifically limited, For example, what is 0.1-10 micrometers can be used, Specifically, it may be 0.3-5 micrometers.

If the average particle diameter of the activated carbon is less than 0.1㎛, not only the price is expensive but also the coagulation phenomenon is severe, so that the coagulation should be alleviated by applying a separate surface treatment agent. It can be difficult to form pores.

Meanwhile, in the first step, the mixture may include 5 parts by weight to 15 parts by weight of titanium alkoxide and 0.5 parts by weight to 7.5 parts by weight of activated carbon based on 100 parts by weight of the solvent.

Here, when the mixture contains less than 5 parts by weight of titanium alkoxide with respect to 100 parts by weight of the solvent, not only the photodegradation effect is lowered but also the synthesis of titanium dioxide may be difficult, and if it contains more than 15 parts by weight. In addition, the photocatalyst concentration is too high, there is a fear that the photolysis effect is reduced due to the loss of light.

In addition, when the mixture contains less than 0.5 parts by weight of activated carbon with respect to 100 parts by weight of solvent, it may be difficult to form micropores, and when it contains more than 7.5 parts by weight, crystallization is promoted to synthesize a titanium dioxide photocatalyst. It can be difficult.

Meanwhile, the solvent may further include an acid or base catalyst for controlling pH and reaction rate and for storage stability and dispersibility of the anatase type titanium dioxide sol.

The acid or base catalyst may be used singly or in combination of two or more catalysts depending on the storage stability and physical properties of the photocatalyst sol.

For example, the acid catalyst may include acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, chlorosulphonic acid, para-toluenesulphonic acid, trichloroacetic acid, polyphosphoric acid, iodic acid, iodic anhydride or perchloric acid, and the like. In addition, the base catalyst may include caustic soda, potassium hydroxide, normal butylamine, imidazole, ammonium perchlorate and the like.

In addition, in the method for preparing a photocatalyst according to the present invention, the first step may include reacting a mixture including a solvent, titanium alkoxide and activated carbon to generate a sol reactant; And fixing the sol reactant on a support.

For example, the sol reactant obtained by reacting the mixture may be fixed on the support by using a wet coating method, and more specifically, the reactant may be supported by a dip coating method. It can be fixed on the phase.

In addition, in the second step, the heat treatment temperature of the reactant obtained in the first step may include all the temperatures that can form fine pores inside the titanium dioxide by burning the activated carbon to discharge carbon dioxide, in particular Although not limited, for example, it may be carried out at a temperature of 400 to 700 ℃, more specifically may be carried out at a temperature of 500 to 600 ℃.

Furthermore, the activated carbon is first sintered at room temperature for 30 minutes to 4 hours, and then secondly sintered at a temperature of 400 ° C to 700 ° C for 30 minutes to 4 hours, thereby simultaneously burning the activated carbon. It can be treated to have crystallinity.

Here, when the heat treatment temperature is less than 400 ℃, combustion of activated carbon and crystallization of titanium dioxide does not occur well, it is difficult to form a titanium dioxide with a uniform distribution of micro pores, and when the temperature exceeds 700 ℃, fine pores This may collapse and the specific surface area of titanium dioxide may decrease.

The present invention also relates to a photocatalyst prepared by the method for producing the photocatalyst.

The photocatalyst prepared by the method for preparing the photocatalyst is a porous photocatalyst having a large increase in specific surface area due to the formation of micropores. The specific surface area is not particularly limited, but may be, for example, 200 to 350 m ² / g. .

When the specific surface area of the photocatalyst is less than 200 m ² / g, the decomposition efficiency of harmful substances may decrease, and when it exceeds 350 m ² / g, the synthesis of titanium dioxide particles may be difficult.

Therefore, the photocatalyst prepared by the method for preparing a photocatalyst according to the present invention may have a superior photo resolution since the specific surface area is significantly increased as compared with the conventional photocatalyst, and thus may exhibit a resolution of 95% or more of volatile organics. .

In addition, the present invention is a support; And a photocatalyst layer formed on the support and containing a photocatalyst according to the present invention.

The type of the support is not particularly limited, but may include, for example, glass, a metal plate, a ceramic plate, various polymers, or an optical fiber. Specifically, an optical fiber can be used in terms of efficient use of light. In other words, in the reactor according to the present invention, the support may include one or more optical fibers.

In addition, the type of the optical fiber is not particularly limited, but a glass-based optical fiber or a plastic-based optical fiber may be used. More specifically, in consideration of the sintering temperature, an optical fiber made of quartz may be used.

The diameter of the optical fiber is not particularly limited, but may be, for example, 0.5 to 5 mm. When the diameter of the optical fiber is less than 0.5mm, it may be difficult to maintain durability of the photocatalyst layer, and when the diameter of the optical fiber exceeds 5mm, partial light source deviation may occur and it may be difficult to maintain a constant light resolution.

Meanwhile, the thickness of the photocatalyst layer is not particularly limited, but may be, for example, 2 to 15 μm, and more specifically 5 to 10 μm. When the thickness of the photocatalyst layer is less than 2 µm, there is a concern that the photo resolution is lowered. When the thickness of the photocatalyst layer is greater than 15 µm, there is a possibility that a loss of light source (ex absorption, reflection, etc.) occurs, and the photo resolution is lowered.

The invention also, the reactor; And a mixing unit for supplying a mixture containing volatile organics and moisture to the reactor.

The photolysis apparatus according to the present invention includes a reactor capable of decomposing various harmful substances using a photocatalyst having an excellent photodegradation effect as described above, and a mixing unit for supplying a mixture containing volatile organic matter and water to the reactor. .

That is, a photocatalyst layer containing a photocatalyst, which exhibits an excellent photodegradation effect due to the large specific surface area, is formed on the surface of the optical fiber, so that a reaction for decomposing harmful substances such as volatile organic matters can be performed, and the mixing portion is such a volatile A mixture containing water with organics is fed to the reactor. Here, the photocatalyst generates high oxidative hydroxyl radicals (-OH) capable of receiving energy from ultraviolet light and decomposing organic matters. As described above, the photocatalyst is supplied with a certain amount of moisture together with volatile organic matters to provide better light. Degradation effect can be exhibited.

In addition, the photolysis apparatus according to the present invention may further include a light supply unit for supplying UV light to the reactor. Although the light quantity and wavelength of the UV light are not particularly limited, for example, the light supply unit may supply UV light having a main wavelength of 300 to 400 nm. In addition, the light supply unit may include a variety of known light sources, and is not particularly limited, for example, a mercury lamp, a BLB lamp may be used.

In addition, the photolysis apparatus according to the present invention may further include a water supply unit for supplying water to the mixing unit. At the time of photodecomposition of the organic matter in the reactor, a better photodegradation effect may be exhibited under constant moisture conditions, and may further include a water supply part for supplying such water to the mixing part to mix with the volatile organic material.

Hereinafter, an optical decomposition apparatus according to an example of the present invention will be described with reference to FIG. 1. However, the light decomposing device illustrated below is only an example of the present invention, and the light decomposing device of the present invention is not limited thereto.

Referring to FIG. 1, the photolysis apparatus 100 according to an embodiment of the present invention includes a light supply unit 110, a reactor 130, a mixing unit 150, and a water supply unit 170.

For example, the light supply unit 110 includes a black light blue lamp (BLB) 111 and a light collector 113, and the UV light emitted from the BLB lamp 111 is a light collector ( 113 is collected by the light collector, and the UV light collected from the light collector is provided inside the reactor 130 and is supplied to the inside of the reactor 130 through an optical fiber 131 having a photocatalyst layer formed on a surface thereof.

The moisture supply unit 170 includes a moisture generator 171, a flow meter 173, and an air compressor 175, and supplies air supplied from the air compressor 175 at a constant flow rate through the flow meter 173. After flowing into the moisture generating device 171, it is supplied to the mixing unit 150 in a state of being mixed with a predetermined amount of water generated by the moisture generating device 171.

The mixing unit 150 receives the VOC 10, air, and water to be decomposed and agitated, and then transfers the mixture to the reactor 130.

The volatile organic material 10 introduced into the reactor 130 is decomposed by the photoreaction of the photocatalyst and discharged through the outlet 133.

In addition, the present invention also relates to a process for decomposing volatile organics comprising the step of supplying a mixture comprising water and volatile organics to the reactor according to the invention.

Here, as described above, the mixture includes moisture together with the volatile organics, and the content of the moisture is not particularly limited, but for example, the mixture may contain 30 to 50% by volume of moisture.

When the content of water in the mixture is less than 30% by volume, not only the photodegradation is deteriorated but also the outer chain (ex. Methyl group, etc.) may be decomposed while maintaining the cyclo structure of the volatile organic matter. Agglomeration of water droplets may occur inside the reactor, which may result in loss of light.

Furthermore, the decomposition method of the volatile organics according to the present invention may further include the step of supplying UV light to the reactor, thereby improving the optical activity.

Hereinafter, the above-described invention will be described in detail based on the following examples. However, the following examples are only for illustrating the present invention, and the present invention is not limited thereto. Analysis of the samples prepared in Examples and Comparative Examples of the present invention was performed by the following method.

(1) photo resolution

Photodegradation was tested by measuring the concentration of organics present in the gas using gas chromatography-mass spectrometry and UV / VIS spectroscopy. The GC-mass spectrometer used HP-6890 from Hewlett-Packard, USA, and the UV-VIS spectrometer used UV-160A from Shimadzu, Japan. The photo resolution was calculated by the following equation.

Resolution (%) = concentration of organics removed / concentration of initial organics

(2) Specific surface area of photocatalyst

Specific surface area of titanium dioxide was used SA3100 Plus of Beckman Coulter, USA, and the sample was measured after fixing for 40 minutes at 200 ℃.

(3) thickness of the photocatalyst layer

The thickness of the photocatalyst film fixed to the glass tube surface was measured by scanning electron microscopy (SEM), XL30 ESEM-FEG, FEI Co., N.Y., U.S.A.

Example 1 Preparation of Photocatalyst

11 parts by weight (15 ml) of TTIP (titanium tetraisopropoxide) was added to 100 parts by weight of ethanol, and stirred for 30 minutes, followed by reaction for 120 minutes by adding 2.29 ml of water. Here, 5.5 parts by weight of activated carbon having an average particle diameter of 0.3 μm was mixed and sufficiently stirred for 10 minutes by an ultrasonicator.

The sol mixture thus prepared was fixed to the surface of the optical fiber by dip coating and then dried at room temperature for 2 hours. The dried photocatalyst was further heat treated (sintered) at 550 ° C. for 2 hours to remove mixed activated carbon and to have crystallization characteristics of titanium dioxide (TiO ₂ ).

The specific surface area of the titanium dioxide photocatalyst thus obtained was 325 m 2 / g, and the thickness of the photocatalyst layer containing the photocatalyst was 4.8 μm.

Surface photographs of the photocatalyst layer containing the photocatalyst prepared as described above are shown in FIGS. 2A (magnification 100 times) and FIG. 2B (magnification 1500 times).

[Examples 2 to 5 and Comparative Examples 1 to 5]

As shown in Table 1 below, except that the content and type of each contained material were different, a photocatalyst was prepared in the same manner as in Example 1, and the photocatalyst layer including the photocatalyst on the optical fiber. Formed.

[Experimental Example]

Photodegradation experiments were carried out using a cylindrical reactor having a diameter of 50 mm and a length of 1 m. In this case, a BLB lamp (6 W, dominant wavelength 365 nm) was used, and 15 glass tubes in the reactor were used.

Subsequently, the mixture including the organic substance and the water to be decomposed is supplied to the reactor including the photocatalysts prepared according to Examples 1 to 5 and Comparative Examples 1 to 5 as shown in Table 1 at a flow rate of 300 mL / sec. After staying for 30 seconds and measured the organic concentration of the exhaust gas collected, it is shown in Table 1 below.

Titanium Dioxide Synthesis Titanium dioxide layer Photolysis process TTIP
(Parts by weight) Alcohol
(100
Parts by weight) Activated carbon Specific surface area
(㎡ / g) thickness
(Μm) moisture
(vol%) Target substance Photo resolution
(%) Particle diameter
(Μm) Parts by weight Example One 11 ethanol 0.3 5.5 325 4.8 30 Styrene 99.8 2 10 Propanol 0.5 4.5 270 5.7 35 Acetone 98.1 3 15 ethanol 1.2 2.5 220 9.2 40 toluene 97.9 4 9 ethanol 3.5 2.0 215 10.3 38 Acetone 96.2 5 12 Butanol 4.4 1.5 207 13.1 46 Styrene 95.0 Comparative example One 10 ethanol 0.3 4.5 320 25 30 Styrene 89 2 12 ethanol 0.4 13 121 5.9 39 Acetone 88 3 10 Butanol 0.5 3.9 256 9.5 15 toluene 85 4 13 ethanol 2.9 4.3 265 0.7 35 Styrene 86 5 12 Propanol - 0 110 4.9 41 Acetone 83

1 is a schematic view showing a photolysis apparatus according to an embodiment of the present invention,

2A and 2B show surface photographs of a photocatalyst layer including a photocatalyst prepared according to Example 1 of the present invention according to magnification.

DESCRIPTION OF THE RELATED ART [0002]

100: photolysis device 10: volatile organic matter

110: light supply portion 111: BLB lamp

113: condenser 130: reactor

131: optical fiber 133: outlet

150: mixing unit 170: moisture supply unit

171: moisture generating device 173: flow meter

Claims (18)

A first step of reacting a mixture comprising a solvent, titanium alkoxide and activated carbon; And And a second step of burning the activated carbon by heat-treating the reactants obtained in the first step. The method of claim 1, The solvent is a method for producing a photocatalyst, characterized in that it comprises at least one selected from the group consisting of water, alcohol and cellosorb. The method of claim 1, Titanium alkoxide is a method for producing a photocatalyst, characterized in that the compound represented by the formula (1): [Formula 1] Ti (OR ₂ ) ₄ In the formula, R ₂ represents an alkyl group having 1 to 6 carbon atoms. The method of claim 3, wherein The titanium alkoxide includes one or more selected from the group consisting of titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetradiisopropoxide, titanium tetrabutoxide, titanium tetraethoxide and titanium tetramethoxide. Method for producing a photocatalyst characterized by. The method of claim 1, Activated carbon is a method for producing a photocatalyst, characterized in that the average particle diameter of 0.1 to 10㎛. The method of claim 1, In the first step, the mixture comprises 5 to 15 parts by weight of titanium tetraalkoxide and 0.5 to 7.5 parts by weight of activated carbon based on 100 parts by weight of the solvent. The method of claim 1, In the second step, the heat treatment is a method of producing a photocatalyst, characterized in that carried out at a temperature of 400 to 700 ℃. The photocatalyst produced by the manufacturing method according to any one of claims 1 to 7. The method of claim 8, A photocatalyst characterized by a specific surface area of 200 to 350 m ² / g. Support; And A reactor comprising a photocatalyst layer formed on the support and containing the photocatalyst according to claim 8. The method of claim 10, And the support comprises at least one optical fiber. The method of claim 13, Reactor, characterized in that the thickness of the photocatalyst layer is 2 to 15㎛. A reactor according to claim 10; And And a mixing unit for supplying a mixture containing volatile organics and water to the reactor. The method of claim 13, And a light supply unit for supplying UV light to the reactor. The method of claim 13, And a water supply unit for supplying water to the mixing unit. A process for decomposing volatile organics, comprising supplying a mixture comprising moisture and volatile organics to a reactor according to claim 10. The method of claim 16, Process for the decomposition of volatile organics, characterized in that the mixture contains 30 to 50% by volume of water. The method of claim 16, A method of decomposing volatile organics, further comprising the step of supplying UV light to the reactor.

Images