KR20070004228A - Adsorbent for recovering volatile organic compound and manufacturing method the same of - Google Patents

Abstract

An adsorbent which can prevent electric discharge of the microwave when irradiating a microwave onto a surface, an adsorbent which is easily controlled by a microwave such that the adsorbent can be promptly guided to a temperature required for thermal desorption of adsorbates, and which can improve adsorbing and desorbing efficiencies of volatile organic compounds by constantly maintaining the temperature required for thermal desorption, and a preparation method thereof are provided. An adsorbent comprises: activated carbon or mesoporous carbon; and a coating layer formed to a predetermined thickness on a surface of the activated carbon or mesoporous carbon. The coating layer is a ferritic compound. The ferritic compound is Ni-Zn-F, Mn-Zn-F, gamma-Fe2O3, or Fe3O4. The coating layer is silica, talc or boron compound. The coating layer has a thickness of 10 mm or less. In an adsorbent for adsorbing volatile organic compounds from a volatile organic compound mixed gas, the adsorbent is zeolite when adsorbing the volatile organic compounds by irradiating a microwave onto the adsorbent. A method for preparing an adsorbent comprises the steps of: mixing a prescribed compound, binder and solvent to form a coating solution composition, and uniformly coating the coating solution composition to a predetermined thickness on the surface of activated carbon or mesoporous carbon; and drying and activating the coated activated carbon or mesoporous carbon.

Description

Adsorbent for recovering volatile hydrocarbons and its manufacturing method {Adsorbent for recovering Volatile Organic Compound and manufacturing method the same of}

1 is a view showing the adsorption recovery process of VOC through the VOC adsorption recovery apparatus according to the present invention.

2 is a view showing the configuration of an experimental apparatus for a microwave heating test according to the present invention.

3 is a graph showing the temperature change of Ni-Zn-Ferrite according to the change of the reflector distance in the experimental apparatus of FIG.

4 is a view showing the flow-through adsorption apparatus described in FIG.

Figure 5 is a graph showing the benzene adsorption isotherm in the spherical activated carbon, Figure 6 is a graph showing the amount of spherical activated carbon with temperature during microwave irradiation.

7 is a graph showing temperature change for microwave irradiation in a coated adsorbent.

8 shows a Talc molecular structure.

9 is a graph showing the temperature increase rate of each adsorbent according to microwave irradiation.

10 is a graph showing the effect of moisture on the temperature increase rate of SiO ₂ / GAC by microwave irradiation.

11A and 11B are graphs showing discharge characteristics of GAC and SiO ₂ / GAC adsorbents.

12 is a graph showing benzene adsorption characteristics of the adsorbent SiO ₂ / GAC.

FIG. 13 is a graph showing the relationship between microwave power and heating rate in the range of 30 ° C. to 40 ° C. (the range in which the temperature rise rate is stabilized even in the case of the magnetic material) of the ferrite magnetic body.

14 is a graph showing the magnetization curve of Mn-Zn-F.

Fig. 15 is a graph showing the relationship between the initial permeability of each magnetic body and the BH loop area (hysteresis curve area), and Fig. 16 shows the initial permeability and heating rate of each magnetic body at 300W. ) Is a graph showing the relationship.

17A, 17B, and 17C are graphs illustrating discharge effects according to temperature changes when microwaves are irradiated to GAC, Ni-Zn-F / GAC, and Mn-Zn-F / GAC, respectively.

18 is a graph showing temperature change when microwaves are irradiated to Ni-Zn-F, Mn-Zn-F, Ni-Zn-F / GAC, and Mn-Zn-F / GAC, respectively.

19A and 19B are graphs showing the degree of influence of uniformity and content of magnetic material coating.

20 is a graph showing the temperature increase rate when microwaves are irradiated to Ni-Zn-F, Mn-Zn-F, Ni-Zn-F / GAC, and Mn-Zn-F / GAC, respectively.

FIG. 21 is a graph showing benzene adsorption characteristics when microwaves are applied to Ni-Zn-F, Mn-Zn-F, Ni-Zn-F / GAC, and Mn-Zn-F / GAC, respectively.

22 is a graph showing the breakthrough curve of zeolite.

FIG. 23 is a graph showing changes in outlet concentrations of benzene and water as a result of microwave irradiation in a conventional adsorption operation.

24 is a schematic diagram showing the adsorption step during microwave irradiation.

25 is a graph showing the relationship between microwave power and benzene adsorption amount.

Fig. 26 is a graph showing the relationship between the microwave power and the relative adsorption amount (Qta / Qw).

FIG. 27 is a graph showing a case where microwave is irradiated to the adsorbent before coating and the adsorbent after coating in the preferred embodiment of the present invention.

[Industrial use]

The present invention relates to an adsorbent and a method for producing the same, and more particularly, to an adsorbent for recovering VOC excellent in adsorption and desorption efficiency with respect to VOC and a method for producing the same, which are easily controlled by microwaves.

[Prior art]

Recent international recognition of Volatile Organic Compounds (VOCs) associated with halocarbons, known as ozone depleting substances, is toxic to humans due to the presence of trace volatile organics in the atmosphere. Increasingly, attention is increasing due to the fact that it acts as a medium for generating photochemical smog. Typical substances of VOC include aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ketones, aldehydes, glycols, ethers and epoxides. Epoxides, phenols, etc. are the major VOC emissions from the current sources, including aliphatic hydrocarbons, aromatic hydrocarbons and halogenated hydrocarbons, accounting for 70% of the total VOC.

VOCs are released into the atmosphere through various paths, which are used as organic solvents in various industrial processes, and are mainly released during the process. In addition, VOCs are emitted during the combustion of automobile exhaust gas, incinerators, waste, wastewater treatment facilities and general households. Although not directly harmful to the human body, the environment as a Photochemical Smong Precusor, which is directly involved in the photolysis reaction of nitrogen oxides in the atmosphere, causing the generation of secondary oxidants such as ozone and aldehydes. There is a pollution problem.

The technical measures to remove VOCs with environmental pollution problems include separation recovery, reuse, and detoxification. Here, available technologies for detoxification (decomposition) include thermal incineration, catalytic incineration, biofiltration, etc., and thermal incineration requires a high temperature, so a sufficient amount of fuel is required and secondary combustion such as NOx is required. Problems such as recontamination by the product may occur, and in case of using a catalyst system, a catalytic heating device using a boiler is required to maintain the catalyst activation temperature. Shortening is a problem.

Therefore, the separation recovery (reuse using adsorption) method has been suggested as one of the useful solutions.The adsorption process using the adsorption principle uses high-purity products by selecting a small amount of investment cost, energy cost, and appropriate adsorbent. There is an advantage that can be obtained.

The activated carbon adsorption method commonly used for VOC recovery takes a lot of time when steam, hot air (hereinafter, steam) or hot nitrogen is used to recover the activated carbon. It is implicated.

In addition, there are problems such as exchange and post-treatment of activated carbon exchanged due to deterioration of adsorption capacity of activated carbon, and wastewater treatment of a used heat source (steam).

Therefore, it is necessary to develop a technology that does not require wastewater treatment, is compact, simple to operate, and low in cost.

The present invention has been made in accordance with the necessity as described above, and an object of the present invention is to provide an adsorbent and a method for producing the same, which can prevent the discharge of microwaves when the surface is irradiated with microwaves.

In addition, it is easy to control by microwave, can be induced to the temperature required for the thermal desorption of the adsorbate in a short time, the temperature required for the thermal desorption can be kept constant, and the adsorbent that can improve the adsorption and desorption efficiency for VOC and its It is an object to provide a manufacturing method.

In order to achieve the above object,

One aspect of the invention,

It provides an adsorbent including activated carbon and the like and a coating layer formed on a surface of the activated carbon to a predetermined thickness.

In addition, the activated carbon is characterized in that any one of activated carbon or mesoporous carbon.

In addition, the coating layer is characterized in that the ferrite compound.

In addition, the ferrite compound is characterized in that any one of Ni-Zn-F, Mn-Zn-F, γ-Fe ₂ O ₃ and Fe ₃ O ₄ .

In addition, the coating layer is characterized in that any one of silica, talc and boron compounds.

In addition, the thickness of the coating layer is characterized in that less than 10mm.

According to another preferred embodiment, in the adsorbent for adsorbing VOC in a VOC mixed gas, when adsorbing the VOC by irradiating microwaves to the adsorbent, the adsorbent is zeolite.

In addition, the adsorption process through the zeolite is characterized in that the adsorption and desorption are simultaneously carried out as the material having a high dielectric constant can be desorbed faster than the smaller material and the material having a low dielectric constant can be adsorbed in the desorbed space.

Another aspect of the invention,

In the method for producing the adsorbent,

Mixing a predetermined compound, a binder and a solvent to form a coating liquid composition, and uniformly coating the surface of activated carbon or the like with a predetermined thickness with the coating liquid composition;

It provides a method for producing an adsorbent comprising the step of drying and activating the coated activated carbon.

In addition, the activated carbon is characterized in that any one of activated carbon or mesoporous carbon.

In addition, the predetermined compound is characterized in that the ferrite compound.

In addition, the ferrite compound is characterized in that any one of Ni-Zn-F, Mn-Zn-F, γ-Fe ₂ O ₃ and Fe ₃ O ₄ .

In addition, the predetermined compound is characterized in that any one of silica, talc and boron compounds.

In addition, the adsorbent coated with silica is characterized in that it is prepared by the sol-gel method.

In addition, the silica-coated adsorbent is a step of dissolving TEOS in ethanol, the step of dissolving the mixture of acetic acid and water after dissolution in the step, and the step of causing hydrolysis and condensation polymerization at room temperature after the infiltration for 2 days Characterized in that it comprises a.

In addition, the silica-coated adsorbent is characterized in that it further comprises the step of calcining at 300 ℃ after drying for 5 hours at 110 ℃.

In the case of the boron, it is characterized in that the adsorbent is prepared by coating boron nitride with the activated carbon in a spray method.

In addition, in the case of talc, a binder is added to Mg ₃ (Si ₄ O ₁₀ ) (OH) ₂ to coat the activated carbon by a physical method to prepare an adsorbent.

In addition, the predetermined thickness is characterized in that 10mm or less.

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

1 is a view showing the adsorption recovery process of VOC through the VOC adsorption recovery apparatus 100 according to the present invention.

As shown in FIG. 1, the VOC adsorption recovery apparatus 100 according to the present invention adsorbs VOC from contaminated air (hereinafter referred to as VOC mixed gas) including VOCs emitted from the atmosphere to remove VOC from clean air (polluted air). Adsorption recovery unit 110 for discharging only the air) and a microwave irradiation unit 120 for irradiating microwaves so that the VOC adsorbed through the adsorption recovery unit 110 is desorbed and recovered.

Here, the microwave irradiation unit 120 is a microwave generator (Microwave Generator) (not shown) for generating a microwave, and a waveguide (Wave Guide) for delivering the microwave generated through the microwave oscillation tube to the adsorption recovery unit 110 ( Not shown).

In addition, a microwave shielding facility (not shown) is installed to prevent the leakage of microwaves to the outside during the microwave irradiation to the adsorption recovery unit 110 through the microwave irradiation unit 120, the adsorption recovery unit 110 is installed on the waveguide It can be installed at the side to prevent external leakage of microwaves.

In addition, the microwave used in the microwave irradiation unit 120 is an Industrial Scientific Medical (ISM) frequency band used for industrial purposes, and this frequency band may correspond to 915 ± 25 MHz, 2450 ± 50 MHz, 5800 ± 70 MHz, and 24125 ± 125 MHz. In the case of microwave heating, the 2450 ± 50 MHz frequency band may be used.

In addition, unlike the conventional two adsorption towers are configured in parallel, the adsorption recovery unit 110 may be composed of one cylindrical or U-shaped adsorption tube or one adsorption tower (hereinafter, single tower).

In addition, the adsorbent 112 for VOC adsorption is formed inside the adsorption recovery unit 110.

In the VOC adsorption recovery apparatus using microwaves configured as described above, when microwave irradiation is performed by the microwave irradiation unit 120 on the adsorption recovery unit 110, the adsorbent (VOC) adsorbed through the adsorbent 112 is desorbed. Clean air is discharged to the outside and only harmful components remain.

The heating test by microwaves is performed by the experimental apparatus 200 shown in FIG. 2, which is a form in which a microwave irradiation apparatus is attached to a general flow-through adsorption apparatus.

The sample (VOC mixed material) supplied through the gas supply device 270 is filled in the adsorption tube 220. The adsorption tube 220 is composed of a U-shaped tube having an inner diameter of 8 mm made of quartz.

In addition, a region (adsorption layer) 221 in which the adsorbent is formed in the adsorption tube 220 is formed.

In addition, the microwave oscillation tube 210 uses a magnetron tube of 2.45 GHz and a maximum output of 1.2 kW, and the microwave is introduced through the waveguide 212 from the oscillation tube 210 and the adsorption tube 220 in the middle of the waveguide 212. Install).

In addition, a microwave power meter 250 connected to the waveguide 212 and the coupler 251 is used to accurately measure the incident force and the reflecting force, and the light in the center of the adsorption layer 221 is not affected by microwaves. A fiberoptic thermometer 240 is installed to measure the internal temperature of the adsorption layer 221.

In addition, a photomultiplier 231 and an amplifier 232 are attached to the adsorption tube 220 to confirm the discharge of the adsorbent, and the discharge peak is confirmed by the digital real time oscilloscope 233. do.

In addition, the VOC adsorption recovery inspection unit 280 is used to measure the VOC concentration of the outlet gas passing through the adsorption tube 220.

In addition, a vibration sample magnetometer (not shown), which is a magnetic characteristic device, may be used to measure physical properties such as magnetization curve or coercive force of the magnetic material.

As shown in Figure 2, in order to increase the energy efficiency in the present device by adjusting the reflector plate 215 located at the end of the waveguide at the position where the microwave is concentrated can be determined the state of the highest efficiency. . When the sample was subjected to 2.1245 g of Ni-Zn-F and the temperature change of the sample was examined while changing the reflecting plate, the result is shown in FIG.

When the reflecting plate is injected about 10mm forward, the highest temperature is shown, but the absorption rate is negative, which means that the amount of microwave output and the amount reflected by the reflecting plate are combined and absorbed by the sample.

In general, since the reflectance is high and includes a problem in confirming an accurate mechanism related to the absorbed wave, an experiment is performed by attaching a device (water channel) 260 for flowing water at the end of the waveguide to remove the amount of microwave reflection. In this case, the microwaves passing through the sample can reduce the microwaves absorbed and reflected by the water.

Meanwhile, as the adsorbent, activated carbon used as a commercial carrier of the adsorbent may be used.

In general, VOC is well adsorbed on activated carbon, but in the case of activated carbon or the like, irradiation with microwaves during VOC desorption causes rapid temperature rise with discharge, whereby the adsorbent can generate secondary pollutants by reaction.

Therefore, the adsorbent should be easy to control by microwave while excellent in adsorption and desorption efficiency, it should be an electrochemically stable adsorbent with excellent microwave dielectric constant.

Hereinafter, the useful adsorbent in the VOC adsorption recovery apparatus using microwaves and a method of manufacturing the same will be described.

In addition, preferred embodiments are presented to aid in understanding the present invention. However, the following examples are provided only to more easily understand the present invention, and the present invention is not limited to the following examples.

Example 1 Adsorbent Coated with Silica, Talc and Boron

In the following, the microwave adsorption characteristics of activated carbon mainly used as adsorbents were examined, and the microwave adsorption characteristics of activated carbon coated with one compound selected from the group consisting of silica (SiO ₂ ), talc and boron (Boron) Find out.

FIG. 4 is an example of the flow-type adsorption apparatus described in FIG. 2, and the adsorption and desorption experiment is performed under conditions of normal temperature (25 ° C.) using spherical activated carbon (GAC), and Cahn Balance. .

Here, the specific surface area of the used GAC is 724 m 2 / g, the adsorbate gas is 530ppm benzene gas concentration adjusted to helium gas, and a binary gas of 10,000ppm moisture is used.

In addition, the flow path unit adjusts the gas flow rate with a gas flow meter (MFC), and the concentration of water is introduced into the water vapor pressure through a saturator maintaining a constant temperature, benzene and water. The silver is mixed well in the mixing chamber (mixing chamber) to be introduced into the adsorption tube, and the gas outlet is wound around the hot wire to maintain about 100 ℃ to prevent condensate from being condensed.

The adsorption tube is made of quartz with very low dielectric loss and uses a U-shaped tube with an inner diameter of 8 mm, and is filled with spherical activated carbon as an adsorbent. The quartz adsorption tube is placed in a thermostat made of Teflon. Flow to control the adsorption bed temperature.

Prior to the adsorption experiment, degassing in a He atmosphere at 150 ° C for 2 hours as a pretreatment process.For the adsorption experiment, 50mmg of adsorbent was placed on a ball (a hemispherical dish containing a sample) of Cahn Balance, and then benzene was placed on a separator. Fill and flow into Cahn Balance using N ₂ gas. At this time, the flow rate of N ₂ was about 100 ml / min, and the adsorption was performed until the breakthrough was reached by introducing benzene into the adsorption reactor in the state of no weight change after stabilization of weight before the adsorption started. When the refrigerant flows outside the adsorption layer to control the temperature of the adsorption layer.

Desorption experiment was stopped after irradiating microwave for a certain time until adsorbent reached breakthrough through adsorption experiment until it heated up to 300 ℃ at 1.6 ℃ / min heating rate and until the outlet concentration of water was equal to the inlet concentration. Continuously analyze the outlet concentration and record the temperature change as the gas continues to flow. At this time, the amount of adsorption and the amount of desorption are calculated by the weight change measured by Cahn Balance.

Experimental operation in the microwave adsorption apparatus is performed in the following procedure. That is, heating is performed while flowing He in the adsorption tube filled with the adsorbent to desorb the adsorbed moisture and impurities. Adsorption gas is introduced into the adsorption tube and adsorption is performed until it reaches breakthrough. At this time, the refrigerant flows outside the adsorption layer to adjust the adsorption layer temperature. When the breakthrough is reached, the microwave is irradiated. The microwave is irradiated for a suitable time and then stopped, and gas is continuously introduced until the outlet concentration of the water is equal to the inlet concentration. Analyze the outlet concentration continuously and record the temperature change.

Experimental results through such adsorption experiments are shown in FIGS. 5 and 6.

5 is a graph showing benzene adsorption isotherms in spherical activated carbon, showing that benzene is well adsorbed on spherical activated carbon. That is, spherical activated carbon has a large adsorption surface area for hydrophobic benzene, and the adsorption capacity increases as the amount of activated carbon micropores and the partial pressure of benzene in the exhaust gas, that is, the ratio of saturated steam pressure, increase.

FIG. 6 is a graph showing the amount of spherical activated carbon according to temperature during microwave irradiation. In the case of spherical activated carbon, continuous irradiation of microwaves causes combustion of the spherical activated carbon.

In other words, if the temperature is gradually increased through microwave irradiation, the weight of spherical activated carbon is decreased. In the vicinity of 100 ° C, the weight decreases due to the desorption of water.

As described above, since spherical activated carbon is discharged from concentration of an electric field surrounding activated carbon particles, there is a possibility of local heating and decomposition, so it is important to develop an adsorbent having no discharge effect.

Therefore, the adsorbent according to the preferred embodiment of the present invention includes a coating layer formed to a predetermined thickness on the surface of the activated carbon.

In addition, the coating layer is at least one member selected from the group consisting of silica (SiO ₂ ), talc (Talc), and boron (Boron) compound.

7 is a graph showing temperature change for microwave irradiation in a coated adsorbent.

As shown in FIG. 7, as the microwave output increases, the temperature of the spherical activated carbon increases linearly, since the spherical activated carbon has a high dielectric constant with respect to microwaves and thus has excellent microwave absorption rate.

In addition, silica (SiO ₂ ) coated adsorbent was the highest temperature after the GAC, Talc / GAC did not occur the temperature rise even if the output increases. It is effective to raise the temperature up to the temperature where benzene can be desorbed with low microwave power. GAC and SiO ₂ / GAC are the most effective when the temperature of desorbed benzene is about 100 ℃. GAC is not suitable as an adsorbent applicable to microwave irradiation because it can be burned by the discharge effect on microwaves. However, Boron / GAC, SiO ₂ / GAC and Talc / GAC adsorbents were examined in 700W household microwave ovens.

In addition, all the adsorbents were heated up to 100 ° C, which appeared to be less than 6 minutes, which is consistent with the fact that microwave heating is an advantage in terms of time loss over conventional heating methods, as Menendez et al.

Boron, SiO ₂ and Talc were selected based on the dielectric constant and temperature stability for microwaves.

Boron has good thermal conductivity and is widely used in the construction of microwave devices, short wave optoelectronic devices and high temperature and high power semiconductor devices.

In addition, SiO _{2, which} is an adsorbent that absorbs microwaves, itself emits microwave energy as thermal energy.

In addition, Talc is a layered hydrous magnesium silicate (Mg ₃ (Si ₂ O ₅ ) ₂ (OH) ₂ ), which is held between layers by van der Waals bonds, and shows the Talc molecular structure in FIG. 8. .

As shown in FIG. 8, Talc has two distinct surface properties, and the Talc plane shows neutral hydrophobicity because there is no broken Si-O and Mg-O bonds, and the broken Si-O and Mg- forms. The corner portion of Talc with O bond is hydrophilic because it has charged Mg ²⁺ and OH ⁻ ions. Malhammar reported that the Talc plane, which consists of tetrahedral siloxane surfaces connected by inactive -Si-O-Si-, accounts for about 90%, which is nonpolar and hydrophobic, and Shortridge et al. Reported that the Talc plane is 69%.

9 is a graph showing the temperature increase rate of each adsorbent according to the microwave irradiation, and the temperature increase rate is related to the desorption rate when designing the microwave adsorption and desorption apparatus. It is economical in operation.

Since as shown in FIG. 9, to absorb from the coated adsorbent SiO ₂ / GAC the I faster the rate of temperature increase than other materials, which is less effective loss modulus of SiO _2, SiO ₂ is water, the effective loss gyesum and moisture content It is determined by (M) that the temperature increase rate is fast.

In other words, Perkin reported that the temperature rise rate when irradiated with RF frequency and microwaves is equal to Equation (1).

Where Pv is the absorption power in each part of the material, a ² is the heat diffusivity, M is the amount of water, H _fg is the enthalpy of evaporation, γ is the density, and C is the specific heat. Also, the last term in the formula is related to the liquid phase. If there is no liquid phase in the material and the temperature is uniform, the formula (1) becomes the formula (2).

As shown in this equation, the rate of temperature rise of a material heated by microwave at a constant frequency depends on the product of the effective loss factor (ε _o ε _e ") times the square of the electric field strength (E), and the effective loss factor is material dependent. Since this is a function of temperature, the rate of rise depends on the effective loss factor of the material.

Therefore, considering the temperature rise and the temperature increase rate of the adsorbent according to the microwave irradiation, in the case of SiO ₂ coated adsorbent, the effect of discharge can be neglected and the hydrophilicity of SiO ₂ acts as an advantage of the temperature rise. SiO ₂ / GAC is considered to be the most suitable adsorbent.

Hereinafter, FIGS. 10 to 12 are graphs showing, in particular, SiO ₂ / GAC as an adsorbent and examining the characteristics thereof.

10 is a graph showing the effect of moisture on the temperature increase rate of SiO ₂ / GAC by microwave irradiation.

As shown in Figure 10, to confirm the temperature increase effect according to the presence or absence of water compared to the case of the case of adding water and dried in SiO ₂ / GAC, it was found that the temperature increase effect is more excellent when the moisture is added . When SiO ₂ is coated, there is an advantage that the effect of the discharge can be ignored, and since SiO ₂ has hydrophilicity, it is determined that the temperature increase rate is increased by the absorbed moisture content (M).

11A and 11B are graphs showing discharge characteristics of GAC and SiO ₂ / GAC adsorbents.

As shown in FIG. 11A, when microwave heating is applied to regenerate GAC, GAC exhibits a sudden temperature rise, frequent discharges, and strong discharge effects. However, as shown in FIG. 11B, a slowness is observed in SiO ₂ / GAC. With the temperature rise, the effect of the discharge hardly occurred. From this, it is judged that the SiO ₂ / GAC adsorbent can be applied to microwave heating.

12 is a graph showing benzene adsorption characteristics of the adsorbent SiO ₂ / GAC.

As shown in FIG. 12, when examining the adsorption capacity before and after coating SiO ₂ on GAC, SiO _{2 /} GAC showed lower adsorption rate and adsorption capacity of benzene than GAC, which can be adsorbed by coating SiO ₂ on GAC. It is believed that the surface area present is due to the relative decrease compared to GAC.

As described above, the adsorbent according to the present invention is coated by adding a small amount of binder to spherical activated carbon with any one of silica, talc, and boron compound, and dried and activated to form SiO ₂ / AC, Talc / AC, Boron / AC. To manufacture.

In general, molasses, sodium silicate, starch, an inorganic binder, and the like may be used as the binder.

In addition, the thickness of the coating layer is preferably 10 mm or less so that uniform heating is performed throughout the adsorbent.

Preparation Example 1.

Silica-coated adsorbent (SiO ₂ / AC) may coat silica (SiO ₂ ) on the surface of activated carbon by a conventional sol-gel method, and more specifically, TEOS (Tetraethoxy-silane: Si) After dissolving (OC ₂ H ₅ ) ₄ ) in a solvent (ethanol), acetic acid and water were mixed and infiltrated, hydrolyzed and condensed at room temperature for 2 days, and the resultant was dried at 110 ° C for 5 hours and then at 300 ° C. By firing at the silica can be prepared an adsorbent (SiO ₂ / AC) coated with silica.

Preparation Example 2

Activated carbon coated with boron may be coated with boron nitride (Boron Nitride) on the activated carbon by a spray method to prepare an adsorbent (Boron / AC).

Preparation Example 3.

The activated carbon (Talc / AC) coated with talc may be coated with activated carbon by physical method by adding a binder to Mg ₃ (Si ₄ O ₁₀ ) (OH) ₂ to prepare an adsorbent (Talc / AC). .

In addition, the components of Talc may be composed of MgO, SiO ₂ , Fe ₂ O ₃ .

Example 2 Adsorbent Coated Magnetic Material

Hereinafter, the microwave adsorption characteristics in the adsorbent coated with a magnetic material made of a ferrite compound on the surface of activated carbon or the like will be described.

Here, the experiment of microwave adsorption characteristics in the adsorbent coated with the magnetic material utilizes the flow-type adsorption apparatus shown in FIG.

As the adsorbent, spherical activated carbon (GAC) is used, and as the magnetic material to be coated, four kinds of Ni-Zn-Ferrite, Mn-Zn-Ferrite, Fe ₃ O ₄ , and γ-Fe ₂ O ₃ are used. The environment is the same as in [Example 1].

Preparation Examples 4 to 7

The adsorbent according to a preferred embodiment of the present invention includes activated carbon and a coating layer formed to a predetermined thickness on the surface of the activated carbon.

In addition, the coating layer is at least one member selected from the group of magnetic materials consisting of a ferrite compound.

That is, the adsorbent according to the present invention is coated with a small amount of binder to the spherical activated carbon as a ferrite compound of Table 1, dried and activated to prepare ferrite / activated carbon (Ferrite / AC).

Table 1 shows four types of ferritic compounds used in the experiments of the present invention: Ni-Zn-Ferrite, Mn-Zn-Ferrite, Fe ₃ O ₄ , and γ-Fe ₂ O ₃ . It is shown. Initial Permeability Loop Area (Oeemu / g) Coercive Force (Oe) Density (g / cm 3) Heating Rate ( ^o C / min) Ni-Zn-F 4,415 3937 21.92 3.207 188.09 Mn-Zn-F 3,323 8530 30.45 2.508 134.23 γ-Fe ₂ O ₃ 1,391 63041 184.6 0.813 107.72 Fe ₃ O ₄ 1,387 52129 187.05 1.088 91.32

Table 2 shows the physical properties of the activated carbon used in the experiment of the present invention.

In addition to the activated carbon, mesoporous carbon may be used as a carrier of the adsorbent.

Filling density (g / ml) Ignition residue (%) Specific surface area (m ² / g) Work volume (ml / g) Average pore diameter (nm) Spherical activated carbon (XL-7100) 0.443 4.3 1101 0.516 1.85

In general, molasses, sodium silicate, starch, an inorganic binder, and the like may be used as the binder.

FIG. 13 is a graph showing the relationship between microwave power and heating rate in the range of 30 ° C. to 40 ° C. (the range in which the temperature rise rate is stabilized even in the case of the magnetic material) of the ferrite magnetic body.

As shown in FIG. 13, the temperature increase rate of Ni-Zn-F was faster than that of Mn-Zn-F.

In addition, when the microwave output was low, the temperature increase rate of the two materials did not change significantly, but the higher the output, the faster Ni-Zn-F appeared. Ni-Zn-F is 188 ° C / min at 300W while Mn-Zn-F is 134 ° C / min.

In addition, the temperature increase rate was in the order of Ni-Zn F>Mn-Zn-F> γ-Fe ₂ O ₃ > Fe ₃ O ₄ . That is, it can be seen that Ni-Zn-F has high temperature stability and high temperature rising rate.

The temperature increase rate is an important factor because it is related to the desorption rate when designing a microwave adsorption device. The faster the temperature rise rate, the shorter the time it can be regenerated, which is more economical to operate the device. In particular, in the microwave recovery apparatus, a single tower continuous process requires a short time regeneration process.

14 is a graph showing the magnetization curve of Mn-Zn-F.

As shown in FIG. 14, as shown in the attained temperature, all of the energy is consumed in the magnetic material as heat energy corresponding to the area during this time. Therefore, the higher the coercive force, the higher the temperature reached, and the smaller the magnetization curve area, the faster the temperature rise.

Fig. 15 is a graph showing the relationship between the initial permeability of each magnetic body and the BH loop area (hysteresis curve area), and Fig. 16 shows the initial permeability and heating rate of each magnetic body at 300W. ) Is a graph showing the relationship.

As shown in FIG. 15 and FIG. 16, there was a tendency that the temperature increase rate increased with the increase of the initial permeability, and the correlation with the magnetic hysteresis curve area was not confirmed. Therefore, in the microwave region, magnetic hysteresis may be the center of the heating principle.

On the other hand, considering the temperature rise and the temperature increase rate of the adsorbent according to the microwave irradiation, Ni-Zn-F and Mn-Zn-F is determined to be the most suitable, Figures 17 to 12 below, in particular, Ni- as a magnetic adsorbent This graph shows the selection of Zn-F and Mn-Zn-F and their characteristics.

17A, 17B, and 17C are graphs illustrating discharge effects according to temperature changes when microwaves are irradiated to GAC, Ni-Zn-F / GAC, and Mn-Zn-F / GAC, respectively.

As shown in FIG. 17A, GAC showed frequent discharge and strong discharge effects with rapid temperature rise, but as shown in FIGS. 17B and 17C, Ni-Zn-F / GAC and Mn-Zn-F In / GAC, the effect of discharge was hardly observed with a slow temperature rise. From this, it is judged that the adsorbent coated with the magnetic material on the GAC can be applied to microwave heating.

FIG. 18 is a graph illustrating temperature change when Ni-Zn-F, Mn-Zn-F, Ni-Zn-F / GAC, and Mn-Zn-F / GAC are irradiated with microwaves, respectively. In this application, temperature control can be considered as an important factor.

As shown in FIG. 18, in the case of Ni-Zn-F and Mn-Zn-F, the temperature rise did not occur linearly even when the microwave output was increased. In other words, Ni-Zn-F maintained a constant temperature at 120 ° C even if the microwave power was increased from around 100W. In the case of Mn-Zn-F, the temperature increased slowly from around 200 ° C and the temperature gradually increased. . The temperature which maintains this constant temperature is near the Curie point of the magnetic material.

Unlike Ni-Zn-F and Mn-Zn-F alone, the temperature of the adsorbent coated with magnetic material on GAC increased with increasing microwave power. In the case of the magnetic material alone, even if the microwave power is increased, it is judged that temperature control is effective because the temperature does not increase continuously, but in the case of the GAC coated with the magnetic material, the effect of the magnetic material alone could not be expected. This is believed to affect the uniformity and content of the magnetic coating on the GAC surface, which can be explained in FIGS. 19A and 19B.

19A and 19B are graphs showing the degree of influence of uniformity and content of magnetic material coating.

19A is a graph showing another temperature rise in the microwave output when the amount of the adsorbent is varied.

As shown in FIG. 19A, when a dry adsorbent is added and the microwave is irradiated, discharge occurs initially. However, when the same adsorbent is continuously tested, the discharge disappears and the temperature is gradually lowered and kept constant.

This may be interpreted as a phenomenon due to heat transfer in the adsorption tube when the amount of the adsorbent increases.

19B is a graph showing the reproducibility test results of the magnetic adsorbent. The adsorbent was tested up to three times continuously under the same conditions (once, twice and three times from above).

As shown in FIG. 19B, as the experiment is repeated, the temperature is gradually lowered and kept constant. The result of this experiment is that a discharge occurs between the fine pores between the adsorbent and the adsorbent. When the discharge occurs, the fine pores are adhered to the adsorbents and current flows between the adsorbents.

20 is a graph showing the temperature increase rate when microwaves are irradiated to Ni-Zn-F, Mn-Zn-F, Ni-Zn-F / GAC, and Mn-Zn-F / GAC, respectively.

As shown in FIG. 20, Ni-Zn-F has a higher temperature increase rate than Mn-Zn-F, and when the microwave output is weak, the temperature increase rate of the two materials is not large, but Ni-Zn increases as the microwave output increases. -F appeared quickly.

In addition, when the magnetic material is coated on the GAC, the difference in temperature increase rate is small when the microwave power is 150W or less, and the Ni-Zn-F / GAC is heated up more than the Mn-Zn-F / GAC as the microwave power is increased to 200W or more. The speed increased slightly. From this point of view, it is possible to confirm the applicability of microwave heating to adsorbents coated with magnetic material on GAC in terms of temperature control.

FIG. 21 is a graph showing benzene adsorption characteristics when microwaves are applied to Ni-Zn-F, Mn-Zn-F, Ni-Zn-F / GAC, and Mn-Zn-F / GAC, respectively.

As shown in FIG. 21, the Ni-Zn-F / GAC and Mn-Zn-F / GAC adsorbents had similar adsorption rates and adsorption amounts for benzene, and adsorption amounts were similar to GAC. However, magnetic materials alone, such as Ni-Zn-F and Mn-Zn-F, hardly adsorbed.

In general, high adsorption and desorption rates can shorten the cycle of the adsorption and desorption process, making the device compact and simple. In this respect, it is judged that the adsorbent coated with the magnetic material is suitable for the microwave heating system.

The adsorbent coated with the magnetic material has been described above, and it is assumed that the magnetic material is uniformly dispersed and coated.

Here, when applying microwave heating to regenerate GAC, GAC magnetic adsorbent coated with Ni-Zn-F and Mn-Zn-F, magnetic materials having good dielectric constant, is developed to develop an adsorbent capable of applying microwave heating while minimizing the discharge effect. As a result of the fabrication, GAC showed frequent discharge and strong discharge effect with rapid temperature rise, but the effect of discharge with little temperature rise was little in Ni-Zn-Fe / GAC and Mn-Zn -F / GAC. .

In addition, the GAC magnetic adsorbent coated with Ni-Zn-F and Mn-Zn-F showed a slower temperature rise than that of GAC alone. Zn-F / GAC and Mn-Zn-F / GAC adsorbents do not show any significant difference from GAC, which can be applied to microwave heating of magnetically coated GAC in the future.

Example 3 Zeolite Adsorbent

Hereinafter, the microwave adsorption characteristics in the case of using the zeolite as the adsorbent will be described.

Here, the experiment of microwave adsorption characteristics in the zeolite utilizes the flow-through adsorption apparatus shown in FIG. 4, and in [Example 3], only the difference with the experimental environment of [Example 1] will be described.

Zeolite is used as the adsorbent, and in particular, NaY zeolite (Na ₅₆ Al ₁₅₆ Si ₁₃₆ O ₃₈₄ ) having a low heating effect by microwaves, a specific surface area of 768 m 2 / g, and having a water content of 24% is used.

22 is a graph showing the breakthrough curve of zeolite.

As shown in Figure 22, the benzene and the water mixture of the two-component system of the adsorption temperature of 25 ℃, flow rate 400ml / min conditions benzene started to break through in about 15 minutes, water breakthrough occurs in about 50 minutes Started. It took about 90 minutes for the two-component system to be fully saturated. In the case of zeolite, the shape of breakthrough curve for multicomponent system in fixed bed adsorption process is known as rollup phenomenon by many researchers. This phenomenon is to replace the strongly adsorbent component in the place where the weakly adsorbent component is adsorbed. When the two-component system of benzene and water flows from the inlet, an adsorption zone is formed from the inlet of the adsorption layer. First, the weakly adsorbent benzene is adsorbed forward and is adsorbed and is replaced with benzene by strongly adsorbent water to proceed with adsorption.

FIG. 23 is a graph showing changes in outlet concentrations of benzene and water as a result of microwave irradiation in a conventional adsorption operation.

As shown in FIG. 23, the upper figure shows the outlet concentration of benzene, the lower figure shows the water outlet concentration, and the center figure shows the temperature change in the adsorption layer.

Here, the microwave output was 0.8 kW, and after the mixed gas of 530 ppm of benzene and 10,000 ppm of water reached breakthrough, the microwave was irradiated at S time point. At this time, the temperature of the adsorption layer is maintained at 25 ° C.

Irradiation of microwave after saturation of the two-component system drastically increased the outlet concentration of water, indicating that the water adsorbed on the zeolite by the microwave was excited and desorbed. As soon as the microwave is irradiated, benzene is desorbed instantaneously, and at this time, it is believed that some of the benzene is adsorbed even in the presence of water.

The desorption concentration of the water continues to increase and then decreases to approach the inlet concentration, indicating that the desorption of the adsorbed water is terminated due to microwave irradiation. On the other hand, in benzene, the exit concentration began to decrease from the point of S. This is because benzene is adsorbed to the empty adsorption site in the zeolite by desorption of water (first adsorption; Qa). Since the decrease in the benzene concentration tended to decrease, adsorption was terminated under microwave irradiation.

When the irradiation of microwaves was stopped at the point E when water and benzene approached the inlet concentration, the concentration of water became smaller than the inlet concentration, which is thought to start normal adsorption on the zeolite because the excitation by the microwaves disappeared. Since the exit concentration of benzene at the same E time point decreases again, benzene after adsorption is completed is adsorbed again (second adsorption; Qa '). As the mixed gas continues to flow without microwave irradiation, benzene was desorbed due to substitutional adsorption of water after the point B, such as the breakthrough curve of the two-component system.

From the above results, it can be seen that the adsorption of water is suppressed in the zeolite having high hygroscopicity in the adsorption-desorption phenomenon by microwave irradiation, whereas the adsorption of benzene is enhanced.

24 is a schematic diagram showing the adsorption step during microwave irradiation.

As shown in FIG. 24, when irradiated with microwaves, water having a high dielectric constant flows out first, and benzene is adsorbed to an empty space of the adsorbent and a temperature rise also occurs.

In detail, in the first step, the entire adsorption layer is filled with water before irradiation with microwaves.

The second step is a step in which water is desorbed by microwave irradiation and benzene is adsorbed (first adsorption) from the inlet to the empty spot. When the microwave is irradiated, the whole system is excited, so the empty spot is not completely filled in the entrance concentration as shown in the figure. If the irradiation time of the microwave is short, the amount of desorption of water decreases and the position where benzene can adsorb becomes small.

In the third step, the irradiation of the microwaves stops the excitation of the whole system and the adsorption of water from the inlet starts. In view of these results, high permittivity water in microwave irradiation can be a good factor for temperature rise. That is, when the microwave is irradiated to the zeolite, the instantaneous temperature can be increased by increasing the instantaneous temperature for desorption of saturated adsorbate, and the effluent concentration can be increased to facilitate recovery.

25 is a graph showing the relationship between microwave power and benzene adsorption amount.

As shown in FIG. 25, when the microwave irradiation time was 15 minutes, the adsorption layer temperature was 25 ° C., and the microwave output was changed from 0.2 kW to 0.8 kW, the first adsorption amount Qa and the second adsorption amount of benzene ( Qa ') and the total adsorption amount (Qa + Qa'), it can be seen that the first adsorption amount and the second adsorption amount increase as the microwave output increases. In addition, as the output of the microwave increased, the total adsorption amount of benzene increased significantly, indicating that the microwave had a great influence on the adsorption.

Fig. 26 is a graph showing the relationship between the microwave power and the relative adsorption amount (Qta / Qw).

As shown in FIG. 26, it can be seen that as the power of the microwave increases, the relative adsorption amount (the adsorption amount of benzene to the amount of desorption of water) increases but the increase decreases as the output increases. That is, it can be seen that the adsorption amount of benzene increases as the output increases, but the adsorption capacity of benzene decreases more than the desorption capacity of water above 0.6 kW.

In general, zeolite has a strong hygroscopic property, and in the case of water-containing benzene, it is known to be inadequate for adsorption of benzene. However, the use of zeolite as an adsorbent is prevented from adsorbing water to some extent by using microwave. You will be able to enlarge it.

In addition, if the dielectric constant is different, the material having a high dielectric constant may desorb more quickly than the small one, and the material having a low dielectric constant may be adsorbed in the desorbed space, so that the adsorption and desorption may proceed simultaneously. It can be controlled within one system.

As described above, by coating a non-magnetic material such as silica, talc, boron, or magnetic material on the activated carbon, it is possible to improve the adsorption and desorption efficiency for VOC while taking advantage of microwave irradiation.

Fig. 27 is a graph showing a case where microwave is irradiated to the adsorbent before coating and the adsorbent after coating in the first and second embodiments of the present invention.

As shown in FIG. 27, (a) before coating, there is a risk of local heating and decomposition due to discharge from concentration of an electric field around activated carbon particles during microwave irradiation.

However, in the case of (b) after coating, the temperature required for thermal desorption of the adsorbate can be kept constant. Therefore, when irradiated with microwaves, the heat desorption of the adsorbate can be induced in a short time, the continuous process can be easily performed in the single-bed column, and the adsorption and desorption efficiency for the VOC can be improved.

On the other hand, the adsorbent described mainly on the activated carbon, but not limited to this may be used mesoporous carbon (Mesoporous Carbon), in particular, mesoporous carbon, pores of 2 ~ 10nm relatively, compared to the material having pores of the unit It is useful because of its uniform pore size distribution.

In addition, for ease of description, the nonmagnetic material is mainly described with silica (SiO ₂ ), and the magnetic material is described with Ni-Zn-F and Mn-Zn-F, but the present invention is not limited thereto. In the case of coating a nonmagnetic material, it may be applied to a case in which magnetic materials of γ-Fe ₂ O ₃ and Fe ₃ O ₄ are coated.

In addition, as an example of the VOC was described mainly benzene, but is not limited to this will be applicable to other VOC.

In addition, the present invention is not limited to the above-described embodiment, and even if a person of ordinary skill in the art makes a design change or avoidance design within a range not departing from the scope of the technical idea of the present invention. Will be in range.

 As described above, the adsorbent and the manufacturing method according to the present invention, by forming a ferrite-based magnetic material or a non-magnetic coating layer of silica, talc, boron, etc. on the surface of activated carbon or mesoporous carbon, when recovering VOC through microwave heating It is possible to prevent the discharge of microwaves in the adsorbent.

In addition, VOC recovery through microwave heating can save energy and time at a faster heating rate, compared to conventional thermal regeneration, there is no direct contact between the heating source and the material to be heated, and can be selectively heated.

In addition, the magnetic or non-magnetic coating can be easily controlled by the microwave, and the temperature required for thermal desorption can be kept constant, thereby improving the adsorption and desorption efficiency for the VOC.

In addition, it is possible to take advantage of economic advantages in terms of operation of the device, such as the energy saving effect of shortening the operating time of the microwave adsorption recovery device.

In addition, since the single-column continuous process can separate and recover the VOC within a short time, the microwave adsorption recovery process is simple, and the VOC adsorption recovery apparatus can be miniaturized.

In general, zeolites are highly hygroscopic and are not suitable for adsorption of benzene in the case of water-containing benzene. However, the use of microwaves prevents the adsorption of water to some extent and results in the adsorption of benzene. It can extend the use of.

Claims (19)

Activated carbon and so on Adsorbent comprising a coating layer formed on the surface of the activated carbon to a predetermined thickness. The method of claim 1, The activated carbon is an adsorbent of any one of activated carbon or mesoporous carbon. The method according to claim 1 or 2, The coating layer is an adsorbent, characterized in that the ferrite compound. The method of claim 3, wherein The ferrite compound is any one of Ni-Zn-F, Mn-Zn-F, γ-Fe ₂ O ₃ and Fe ₃ O ₄ characterized in that the adsorbent. The method according to claim 1 or 2, The coating layer is adsorbent, characterized in that any one of silica, talc and boron compound. The method of claim 1, Adsorption agent, characterized in that the thickness of the coating layer is 10mm or less. In the adsorbent which adsorbs VOC in a VOC mixed gas, When adsorbing the VOC by irradiating microwave to the adsorbent, the adsorbent is a zeolite, characterized in that the zeolite. The method of claim 7, wherein The adsorption process through the zeolite is characterized in that the adsorption and desorption are simultaneously carried out as the material having a high dielectric constant is desorbed faster than the smaller material and the material having a low dielectric constant can be adsorbed in the desorbed space. In the method for producing the adsorbent, Mixing a predetermined compound, a binder and a solvent to form a coating liquid composition, and uniformly coating the surface of activated carbon or the like with a predetermined thickness with the coating liquid composition; Method of producing an adsorbent, characterized in that it comprises the step of drying and activating the coated activated carbon. The method of claim 9, The activated carbon is a method for producing an adsorbent, characterized in that any one of activated carbon or mesoporous carbon. The method according to claim 9 or 10, The predetermined compound is a method for producing an adsorbent, characterized in that the ferrite compound. The method of claim 11, The ferrite compound is a method for producing an adsorbent, characterized in that any one of Ni-Zn-F, Mn-Zn-F, γ-Fe ₂ O ₃ and Fe ₃ O ₄ . The method according to claim 9 or 10, The predetermined compound is a method for producing an adsorbent, characterized in that any one of silica, talc and boron compounds. The method of claim 13, The silica coated adsorbent is prepared by a sol-gel method. The method of claim 14, The silica-coated adsorbent comprises dissolving TEOS in ethanol, precipitating by mixing acetic acid and water after dissolving in the step, and causing hydrolysis and condensation to occur for 2 days at room temperature after the precipitating. Method for producing an adsorbent, characterized in that. The method of claim 15, The silica-coated adsorbent is dried for 5 hours at 110 ℃ and then calcining at 300 ℃ manufacturing method of the adsorbent characterized in that it further comprises. The method of claim 13, In the case of the boron, the method for producing an adsorbent, characterized in that the boron nitride is coated on the activated carbon or the like by a spray method to produce an adsorbent. The method of claim 13, In the case of the talc, a binder is added to Mg ₃ (Si ₄ O ₁₀ ) (OH) ₂ to coat the activated carbon by a physical method to prepare an adsorbent. The method of claim 9, The predetermined thickness is a manufacturing method of the adsorbent, characterized in that less than 10mm.

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