KR20140023661A - Membrane for sulfur dioxide separation and preparation method thereof - Google Patents

Abstract

The present invention relates to a separation membrane for sulfur dioxide separation and a preparation method thereof, more specifically to a separation membrane for sulfur dioxide separation which includes a polyether block amide and polyethylene glycol and a preparation method thereof. The separation membrane of the present invention has high transmittancy for SO2 and selectivity for SO2 against CO2, and is capable of being applied to a ultra-clean desulfurization technique for collecting CO2.

Description

Membrane for Sulfur dioxide Separation and Preparation Method Thereof}

The present invention is SO ₂ The present invention relates to a membrane for separating sulfur dioxide that can be applied to ultra-clean desulfurization technology for capturing carbon dioxide and having a high selectivity to SO ₂ for permeability and CO ₂ .

Flue gas desulfurization (FGD) is an environmental pollution prevention system that absorbs and reacts sulfur oxides (SOx) generated when burning fossil fuels such as coal and petroleum to limestone and sludge and generates gypsum as a byproduct. .

As of the end of 2010, a total of 59 flue gas desulfurization plants were operating in domestic thermal power plants.In addition, KEPCO is an industrial boiler other than KEPCO. Many facilities are in operation.

Most plants using limestone zero absorption reaction by the wet limestone gypsum process, and to produce gypsum as a reaction product is sold as a raw material of cement or gypsum board, but in recent years its own because of the utilization frequency of the increase in sulfur fuel inlet SO ₂ concentration rises and As a result, deterioration of operating conditions of the desulfurization process lowers the quality of gypsum, which threatens recycling.

SO ₂ during desulfurization problems Problems caused by reduced removal rate include increased exhaust gas flow rate, increased GGH leakage rate, absorption tower PH, oxidation air flow rate decrease, absorption tower water level imbalance due to partial blockage of oxidation air distribution pipe, limestone blinding ), Absorbent particle size and purity, inlet SO ₂ There is an increase in concentration and a decrease in L / G ratio.

With the recent development of carbon capture and storage (CCS) technology to reduce greenhouse gas emissions, the level of carbon capture (CO ₂₎ capture has reached the commercialization stage. have.

Since coal has a high C / H ratio among fossil fuels, coal combustion facilities have become a major target for reducing CO ₂ emissions. Flue Gas Desulfurization (FGD) has been installed and operated in domestic coal-fired power plants, but SO ₂ is emitted by several tens of ppm by current technology level or operating conditions.

As an example of a desulfurization process, Korean Patent Registration No. 10-1121912 discloses an apparatus for treating sulfur oxides in exhaust gases including an absorption tower for removing sulfur oxides contained in exhaust gases introduced therein, wherein the absorption tower is an electric furnace slag. It includes an inlet pipe for introducing the leachate of the treatment plant and the discharge pipe for discharging the leachate to the outside, the sulfur oxide contained in the exhaust gas is removed by the reaction of the leachate and the exhaust gas introduced through the inlet pipe The apparatus for treating sulfur oxides of exhaust gas is characterized in that the leachate is discharged through the discharge pipe.

This SO ₂ is to give an adverse effect on performance due to the contamination of the collected CO ₂ CO ₂ storage process by the deterioration of the absorber used in the process when entering the CO ₂ absorption step, so CO ₂ The introduction of various pollutants, including SO _2, into the capture process is strictly regulated.

It is common that SO ₂ should not exceed 10 ppm, and the MHI also aims to regulate it below 1 ppm. In order to cope with SO ₂ inflow conditions required by the CO ₂ capture process, in order to keep the SO ₂ concentration below 10ppm by increasing the desulfurization efficiency to 99.5% in the existing flue gas desulfurization process, the geometric size of the absorption tower is greatly reduced. (2 times or more) Basic facilities or devices such as circulation pumps should be added or replaced in a large capacity to increase the circulation of absorbent reaction liquids and to improve the filling and internal structure.

Therefore, in the case of adding a CO ₂ capture facility in a facility that is already installed and in operation, it is often impossible to drastically modify the existing flue gas desulfurization facility. In such cases, the introduction of additional ultra-clean flue gas desulfurization facilities is inevitable.

Therefore, there is an urgent need for a super clean desulfurization process for supplementing the performance of the existing desulfurization process (FGD) and maintaining the operation efficiency and economical efficiency of the carbon dioxide storage and storage process.

In particular, the membrane separation process is evaluated as one of the most energy-saving technologies among various gas separation technologies including carbon dioxide because it does not require additional energy (latent heat) for phase change during the separation process. The device elements are very simple intensive, very simple to operate and control, and easy to scale.

Thus, SO ₂ If the membrane with high selectivity for gas is applied to the desulfurization process, it can be additionally applied to the existing process, and it is easy to replace the damaged or problematic separator module and can be stacked in units of modules. Do.

Korea Patent Registration No. 10-1121912

In order to improve the above problems, an object of the present invention is to provide a membrane for separation of sulfur dioxide having a high permeability to SO ₂ and a high selectivity to SO ₂ for CO ₂ , and a method for manufacturing the same.

To this end, the present invention provides a separator for separating sulfur dioxide comprising polyether block amide and polyethylene glycol.

In addition, the present invention comprises the steps of: 1) coating a substrate with a polymer solution containing polyether block amide, polyethylene glycol and a solvent to form a polymer film; And 2) provides a method for producing a separator for sulfur dioxide separation, comprising the step of drying the polymer membrane.

Membrane according to the invention is SO ₂ The high permeability and selectivity to SO ₂ for CO ₂ make it useful for ultra clean desulfurization technology for CO2 capture.

1 is a graph showing the selectivity for the gas permeability of the separator prepared in Comparative Example 1.
2 is a graph showing the selectivity of the separator prepared in Examples 1 to 3 and Comparative Example 1.
3 is a graph showing the selectivity of the separator prepared in Examples 4 to 6 and Comparative Example 1.

Hereinafter, the present invention will be described in detail.

The separator for separating sulfur dioxide according to the present invention includes polyether block amide and polyethylene glycol.

Polyether block amide is a polyamide-based thermoplastic elastomer. It is composed of polyamide, which is a hard segment, and polyether, which is a soft segment. The polyether block amide has both durability and flexibility of polyamide.

The polyether block amide has a degree of hydrophilicity depending on the ratio of polyamide / polyether, and high hydrophilicity is preferable for the selective separation of sulfur dioxide. For this purpose, the polyamide content constituting the polyether block amide is preferably 30 to 50% by weight. More preferably, PEBAX 1657 is used as the polyether block amide.

The polyethylene glycol preferably has a molecular weight of 200 to 800. The molecular weight of the polyethylene glycol is a range capable of forming a film by mixing with the polyether block amide at the time of manufacturing the separator, when the molecular weight is less than the above range, the permeability and selectivity to sulfur dioxide is lowered, if the above range is exceeded the polyether block Incompatibility with amides is not easy.

At this time, the mixing ratio of polyether block amide and polyethylene glycol is preferably 1: 0.2 to 1: 0.5, and when the ratio is 1: 0.5, the permeability to sulfur dioxide is the best. As the content of polyethylene glycol increases, the permeability to sulfur dioxide is excellent, and if it is above the above range, the durability of the membrane is lowered, and thus it is not suitable as a membrane for sulfur dioxide separation.

Polyether block amide and polyethylene glycol, which are the materials of the separator according to the present invention, are hydrophilic polymers, and the durability of the separator may decrease due to contact with water with time. The present invention optionally crosslinks polyethylene glycol with a crosslinking agent to improve durability.

Such a separator of the present invention is SO ₂ The permeability is more than 3900 Barrer, the SO ₂ / CO ₂ selectivity is more than 40, especially high SO ₂ selectivity for CO ₂ can be usefully applied to ultra-clean desulfurization technology for carbon dioxide capture.

Such a separator of the present invention,

1) coating a substrate with a polymer solution containing polyether block amide, polyethylene glycol and a solvent to form a polymer film; And

2) is prepared through the step of drying the polymer film.

Each step will be described in more detail below.

First, a substrate is coated with a polymer solution containing polyether block amide, polyethylene glycol, and a solvent to form a polymer film.

Examples of the substrate that can be used in the present invention include glass, silicon, plastic, and the like. The polymer solution as described above is coated onto the substrate to a thickness of several tens to hundreds of micrometers according to conventional methods known in the art. For example, doctor's knife, spin coating, dip coating, roll coating, screen coating, spray coating, flow coating, The polymer solution may be coated onto the substrate using screen printing, ink jet or drop casting.

The solvent is not particularly limited as long as it can uniformly dissolve and disperse the polyether block amide and polyethylene glycol. Preferably the solvent uses isopropanol, ethanol, methanol, acetone or mixtures thereof.

In this case, the polymer solution may include 3 to 9 wt% of polyether block amide, 0.6 to 4.5 wt% of polyethylene glycol, and the remainder of the solvent.

If the content of each component is less than the lower limit or exceeds the upper limit there is a problem that the selectivity and permeability for sulfur dioxide is lowered.

In this case, optionally, the polymer solution may further include a crosslinking agent to crosslink the polyethylene glycol. At this time, glutaraldehyde, isophthaloyl dichloride, 1,3,5-benzenetricarbonyl trichloride, or toylene-2,4-diisocyanate may be used as the crosslinking agent.

 At this time, the content of the crosslinking agent is preferably 0.09 to 0.27% by weight of the polymer solution. If the content of the crosslinking agent is less than the above range, the crosslinking reaction is insignificant, and if it exceeds the above range, there is a problem that the permeability of the separator obtained due to excessive crosslinking reaction is lowered.

Such a crosslinking agent reacts with and crosslinks the functional group of polyethylene glycol, thereby further improving the stability and durability of the separator.

Next, the polymer film is dried.

At this time, the drying conditions are not particularly limited in the present invention, but are carried out under the conditions capable of sufficiently removing the solvent. Preferably it is carried out at 30 to 150 ℃ for 30 minutes to 10 hours, if necessary under reduced pressure.

Hereinafter, preferred embodiments of the present invention will be described. The following examples are provided for the purpose of more clearly illustrating the present invention and are not intended to limit the scope of the present invention.

Experimental material

Polyether Block Amides (PEBAX, Arkema SA, France) 1657 required for the experiment was used. The solvent was produced and used from ethanol (JTBaker, Malaysia) and ultrapure water (Younglin Pure Water System, Seoul Korea). As an additive, polyethylene glycol (Polyethylen Glycol, Aldrich Co. Milwakee, Mw = 400) was used, and a crosslinking agent was glutaraldehyde (Glutaraldehyde, Junsei Chemical Co. Ltd). The above products were used without further purification.

      (Example 1)

The PEBAX 1657 polymer was completely dissolved in 70 wt.% Ethanol aqueous solution for 2 hours in a water bath (about 100 ± 1 ° C.), and then a 3 wt.% PEBAX solution was prepared. 0.6 wt.% Of polyethylene glycol was added to a 3 wt.% PEBAX solution, and stirred at room temperature (about 24 ± 1 ° C.) for 24 hours to prepare a solution. The prepared solution was poured into a glass frame of about 7 ~ 7cm 15 ~ 20ml and dried for 3 hours at 60 ℃ vacuum oven to prepare a membrane.

(Example 2)

A separator was prepared in the same manner as in Example 1 except that 1.2 wt.% Of polyethylene glycol was used.

(Example 3)

A separator was prepared in the same manner as in Example 1 except that 1.5 wt.% Of polyethylene glycol was used.

(Example 4)

The PEBAX 1657 polymer was completely dissolved in 70 wt.% Ethanol aqueous solution for 2 hours in a water bath (about 100 ± 1 ° C.), and then a 3 wt.% PEBAX solution was prepared. 1.5 wt.% Polyethylene glycol was added to 3 wt.% PEBAX solution, stirred at room temperature (about 24 ± 1 ° C.) for 24 hours, and then 0.09 wt.% Glutaraldehyde was added and stirred for 24 hours to prepare a mixed solution. The prepared solution was poured into a glass frame of about 7 ~ 7cm 15 ~ 20ml and dried for 3 hours at 60 ℃ vacuum oven to prepare a membrane.

(Example 5)

Separation membrane was prepared in the same manner as in Example 3 except that glutaraldehyde was used at 0.18 wt.%.

(Example 6)

Separation membrane was prepared in the same manner as in Example 3 except that 0.27 wt.% Glutaraldehyde was used.

(Comparative Example 1)

Separation membrane was prepared in the same manner as in Example 1 except that polyethylene glycol was not used.

(Experimental Example 1)

Gas permeability was measured using a permeability measuring device (Time-lag) to investigate the gas permeation characteristics of the prepared membrane. The permeability measuring device was placed in a thermostat and kept at a constant temperature of 25. The gas permeability coefficient was calculated by the following equation (1) from the slope of the time-pressure curve after reaching a steady state where the rate of pressure increase over time became constant.

(1)

(One)

]는 투과부의 부피, A[

]는 막의 투과면적,

[cmHg]은 공급부 압력, T[K]는 온도, R은 기체상수, 그리고 p/t는 투과부의 압력변화 속도를 나타낸다. 투과도 계수, P는 GPU 단위를 사용하였으며, 1 GPU는 10^-6(STP)/cm²·sec·cmHg이다. 이상분리인자는 다음의 식(2)와 같이 순수기체 투과도 계수의 비로 정의 되며, 확산 선택도(diffusivity selectivity)와 용해선택도(solubility selectivity)의 곱으로 나타낼 수 있다. 확산선택도는 분리막이 기체의 크기와 모양을 구별할 수 있는 매체로서의 기능을 수행할 수 있는가에 기초한 것으로, 사슬의 운동성이나 사슬간의 충진(packing)등에 의하여 변화하며, 용해선택도는 기체의 응축성과 기체와 분리막간의 상호작용 등에 의해 결정된다.Where V [

] Is the volume of permeate, A [

] Is the permeation area of the membrane,

[cmHg] is the feed pressure, T [K] is the temperature, R is the gas constant, and p / t is the rate of pressure change in the permeate. The transmittance coefficient, P, was used in GPU units, and one GPU was 10 ⁻⁶ (STP) / cm ² · sec · cmHg. The anomaly separation factor is defined as the ratio of the pure gas permeability coefficients as shown in Equation (2), and can be expressed as the product of diffusivity selectivity and solubility selectivity. The diffusion selectivity is based on whether the membrane can function as a medium to distinguish the size and shape of the gas. The diffusion selectivity is changed by chain mobility or packing between the chains. Performance and the interaction between the gas and the membrane.

(2)

(2)

      Gas permeability measurement results of the separators of Examples 1 to 6 and Comparative Example 1 are shown in Table 1 below.

N ₂ O ₂ CO ₂ SO ₂ Comparative Example 1
Gas permeability
(Barrer *) 0.9 2.6 47.9 2192.0 Diffusivity ** 3.21 × 10 ^-7 7.58 × 10 ^-7 5.28 × 10 ^-6 4.52 × 10 ^-7 Solubility *** 0.00028 0.00034 0.00906 0.48496 Example 1

Gas permeability
(Barrer *) 1.3 3.6 82.6 3900.0 Diffusivity ** 3.61 × 10 ^-7 8.00 × 10 ^-7 7.01 × 10 ^-7 6.09 × 10 ^-7 Solubility *** 0.00036 0.00045 0.01196 0.55521 Example 2

Gas permeability
(Barrer *) 2.3 5.2 112.0 5993.8 Diffusivity ** 4.04 × 10 ^-7 8.39 × 10 ^-7 7.41 × 10 ^-7 8.10 × 10 ^-7 Solubility *** 0.00057 0.00062 0.01510 0.73993 Example 3

Gas permeability
(Barrer *) 3.1 7.0 186.3 9039.6 Diffusivity ** 4.92 × 10 ^-7 8.43 × 10 ^-7 7.71 × 10 ^-7 9.92 × 10 ^-7 Solubility *** 0.00063 0.00083 0.02415 0.9100 Example 4
Gas permeability
(Barrer *) 1.5 3.8 81.6 3896.4 Diffusivity ** 1.53 × 10 ^-7 2.99 × 10 ^-7 8.63 × 10 ^-7 7.91 × 10 ^-7 Solubility *** 0.00098 0.00127 0.00946 0.49259 Example 5

Gas permeability
(Barrer *) 1.7 4.2 95.0 4975.7 Diffusivity ** 1.24 × 10 ^-7 2.56 × 10 ^-7 7.07 × 10 ^-7 9.51 × 10 ^-7 Solubility *** 0.00137 0.00164 0.01343 0.52320 Example 6

Gas permeability
(Barrer *) 1.8 4.6 114.8 6081.5 Diffusivity ** 9.52 × 10 ^-8 2.14 × 10 ^-7 6.11 × 10 ^-7 1.7 × 10 ^-6 Solubility *** 0.00189 0.00214 0.01876 0.56836 ^{* Barrer: 10 -10 (cm 3} (STP) cm / cm 2 · s · cmHg, ** 10 -7 cm 2 / s, *** 1 -3 (STP) / cm 3 · cmHg

As shown in Table 1, the separation membrane showed a tendency to increase the transmittance in the order of N ₂ <O ₂ <CO ₂ <SO ₂ . The permeability of the separator of Example 1 was improved by 31% N ₂ , 28% O ₂ , 42% CO ₂ , and 44% SO ₂ compared with Comparative Example 1. In the case of Example 2, it was confirmed that the permeability of the separator was improved compared to Comparative Example 1 N ₂ 61%, O ₂ 50%, CO ₂ 57%, SO ₂ 63%. Polyethylene glycol 1.5 wt.% Of the membrane in Example 3 was added is confirmed in comparison with Comparative Example 1 that the transmission rate is _{N 2 71%, O 2 63} %, CO 2 74%, SO 2 76% improved. Also, as the amount of glutaraldehyde added increased, the permeability to N ₂ , O ₂ , CO ₂ , SO ₂ tended to increase.

Figure 1 shows the selectivity for the gas permeability of the separator prepared in Comparative Example 1. Referring to FIG. 1, the selectivity value of CO ₂ / N ₂ showed the largest value, and was decreased in the order of SO ₂ / CO ₂ and O ₂ / N ₂ . The choice of SO ₂ for CO ₂ was also 46.

Figure 2 is a graph showing the selectivity for the separator prepared in Examples 1 to 3 and Comparative Example 1. 2, the selectivity was increased in the order of O ₂ / N ₂ <SO ₂ / CO ₂ <CO ₂ / N ₂ , and in Example 2, the selectivity of SO ₂ / CO ₂ was CO ₂ / N _2. Larger than The selectivity of SO ₂ / CO ₂ was over 40.

3 is a graph showing the selectivity for the separator prepared in Examples 4 to 6 and Comparative Example 1. Referring to FIG. 3, the selectivity was increased in the order of N ₂ / CO ₂ <SO ₂ / CO ₂ <CO ₂ / N ₂ , and SO ₂ / CO ₂ in Example 6 using 0.27 wt.% Glutaraldehyde. Selectivity exhibited a value of at least 50 overall.

Claims (13)

Separation membrane for the separation of sulfur dioxide containing polyether block amide and polyethylene glycol. The separator for separating sulfur dioxide according to claim 1, wherein the polyamide content of the polyether block amide is 30 to 50% by weight. The separator for sulfur dioxide separation according to claim 1, wherein the polyether block amide is PEBAX 1657. The separator for sulfur dioxide separation according to claim 1, wherein the polyethylene glycol is crosslinked by a crosslinking agent. The separation membrane for sulfur dioxide separation according to claim 1, wherein the mixing ratio of the polyether block amide and polyethylene glycol is 1: 0.2 to 1: 0.5. The separator for sulfur dioxide separation according to claim 1, wherein the SO ₂ / CO ₂ selectivity of the separator is 40 or more. 1) coating a substrate with a polymer solution containing polyether block amide, polyethylene glycol and a solvent to form a polymer film; And
2) drying the polymer membrane
A method of manufacturing a separator for sulfur dioxide separation comprising a. 8. The method of claim 7, wherein the solvent is isopropanol, ethanol, methanol, acetone or a mixture thereof. The method of claim 7, wherein the content of the polyether block amide in the solution is 3 to 9 wt%. The method of claim 7, wherein the content of polyethylene glycol in the solution is 0.6 to 4.5 wt%. 8. The method of claim 7, wherein the solution further comprises a crosslinking agent. 12. The method of claim 11, wherein the crosslinking agent is for separating sulfur dioxide, characterized in that glutaraldehyde, isophthaloyl dichloride, 1,3,5-benzenetricarbonyl trichloride, or toylene-2,4-diisocyanate Method of preparing a separator. 12. The method of claim 11, wherein the content of the crosslinking agent in the solution is 0.09 to 0.27 wt%.

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