KR20190017475A - Method for Simultaneous Treating Nitrogen Oxides and Sulfur Oxides using Iron Ethylene diamine tetraacetic acid - Google Patents

Abstract

The present invention relates to a method for simultaneously reducing nitrogen oxides (NO_x) and sulfur oxides (SO_x) contained in a power plant exhaust gas and recovering nitrogen oxides and sulfur oxides as fertilizer type nitrate and sulfate. Harmful gases are efficiently collected through an integrated scrubber simultaneously and converted into a fertilizer form through a simple electrochemical device with low space consumption. Accordingly, the present invention is a processing apparatus and method approaching commercialization in consideration of initial equipment investment cost and operation easiness while having excellent removal efficiency and being economical.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for simultaneous treatment of nitrogen oxides and sulfur oxides using iron-ethylenediaminetetraacetic acid (METHOD FOR SIMULTANEOUSLY Treating Nitrogen Oxides and Sulfur Oxides using iron Ethylene diamine tetraacetic acid)

The present invention relates to a method of treating exhaust gas from a power plant, and more particularly, to a method of simultaneously recovering nitrogen oxides (NO _x ) and sulfur oxides (SO _x ) contained in exhaust gas of a power plant by nitrate and sulfate .

In the combustion process of fossil fuel use facilities and automobile engines such as power generation facilities, industrial boilers, and incineration facilities, a large amount of nitrogen oxide which is harmful to the human body is generated, and this emission of nitrogen oxide causes acid rain, reduction of ozone layer and generation of photochemical smog And even the main cause of fine dust.

Processes for removing these include selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR), electron beam utilization, and pulse corona discharge (NH ₃ ) Processes have been researched and developed. As a result of the development of the nitrogen oxides abatement technology, the emission of nitrogen oxides has decreased slightly in recent 10 years. However, in the US alone, about 30 million tons of nitrogen oxides are emitted annually. The selective catalytic reduction, SCR) requires an astronomical amount of about $ 24 billion.

Sulfur oxides can be treated through various processes such as dry and wet desulfurization processes. The most commercially available processes include flue gas desulfurization (FGD), which removes sulfur oxides using calcium or lime . However, the calcium sulfide collected as the final product is low in recyclability and toxic heavy metals such as mercury are utilized in the process, thereby causing secondary environmental problems (Non-Patent Document 2).

Recently, due to concerns due to fine dusts, environmental standards have been strengthened and interest in reduction of nitrogen oxides and sulfur oxides has been increasing, and studies are being conducted to effectively treat them at the same time, but there are no commercially available processes Document 1, Patent Document 1). Especially, considering the space velocity and gas flow rate of the power plant flue gas, it is necessary to develop a technology that is excellent in field application.

Accordingly, the present inventors have made extensive efforts to develop a method for efficiently and economically treating nitrogen oxides and sulfur oxides at the same time. As a result, they have found that by collecting nitrogen oxides and sulfur oxides simultaneously in an exhaust gas from a power plant using an integrated scrubber, It is possible to efficiently remove nitrogen oxides and sulfur oxides at the same time, and the present invention has been accomplished.

Apparatus for improving performance of electrochemical mediated oxidation process for treating NOx, SOx and dioxins (Application No.: 10-2008-0008837)

 The Chemical Behaviors of Nitrogen Dioxide Absorption in Sulfite Solution. Appl. Sci. 7: 377,2017.  Simultaneous removal of NOx and SO2 from flue gas using Na2SO3 assisted electrochemical reduction and direct electrochemical reduction. J. Hazard. Mater. 276: 371, 2014.

It is an object of the present invention to provide a method for efficiently and economically treating nitrogen oxides and sulfur oxides present in an exhaust gas simultaneously.

It is another object of the present invention to provide an apparatus for efficiently and economically treating nitrogen oxides and sulfur oxides present in an exhaust gas simultaneously.

In order to accomplish the above object, the present invention provides a method of producing a carbon nanotube, comprising: (a) simultaneously absorbing nitrogen oxides and sulfur oxides with an absorbent based on iron and ethylenediaminetetraacetic acid; (b) regenerating an absorbing solution produced by absorbing nitrogen oxides and sulfur oxides from the absorbent in an electrochemical cell having an electrode structure of micro pores; And (c) applying the regenerated absorbing solution to an electrochemical cell comprising an anion exchange membrane to produce a nitrate and a sulfate, and further regenerating the absorbed liquid, wherein the nitrogen oxide and sulfur oxide The method comprising:

The present invention also relates to a process for the preparation of (i) a scrubber which comprises an absorbent based on iron and ethylenediaminetetraacetic acid and which simultaneously absorbs nitrogen oxides and sulfur oxides; (ii) an electrochemical cell having an electrode structure of microvoids regenerating the absorption liquid absorbed in the scrubber; And (iii) an electrochemical cell including an anion exchange membrane for producing nitrate and sulfate in an absorption liquid regenerated in the electrochemical cell, the present invention provides an apparatus for simultaneous treatment of nitrogen oxides and sulfur oxides using iron-ethylenediamine tetraacetic acid .

The simultaneous treatment of nitrogen oxides and sulfur oxides according to the present invention can convert both nitrogen oxides and sulfur oxides, which could not be simultaneously treated in the prior art, into fertilizer type nitrate and sulfate, It is easy to commercialize because it is low in initial equipment investment cost and easy to operate.

1 shows an apparatus for simultaneous treatment of nitrogen oxides and sulfur oxides using iron-ethylenediaminetetraacetic acid according to the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein and the experimental methods described below are well known and commonly used in the art.

In the present invention, a process for converting nitrogen oxides and sulfur oxides into iron nitrate and sulfuric acid through electrochemical treatment using iron-ethylenediaminetetraacetic acid as an absorbent and simultaneously developing iron-ethylenediamine It is possible to remove nitrogen oxides and sulfur oxides at the same time through the integrated scrubber using tetraacetic acid as the absorbent, and it is possible to use the shape of the scrubber used in the conventional flue gas desulfurization process as it is and to use the initial investment cost, installation period, Can be greatly improved. In addition, nitrogen oxides and sulfur oxides of flue-gas can be utilized as waste fertilizer or high-purity fertilizer instead of difficult-to-treat by-products. As a result, it is expected that it will be possible to provide technology that is close to commercialization and has excellent application in the field.

Accordingly, in one aspect, the present invention provides a method for the production of iron oxide, comprising: (a) simultaneously absorbing iron and an ethylene diamine tetraacetic acid based absorbent with nitrogen oxides and sulfur oxides; (b) regenerating an absorbing solution produced by absorbing nitrogen oxides and sulfur oxides from the absorbent in an electrochemical cell having an electrode structure of micro pores; And (c) applying the regenerated absorbing solution to an electrochemical cell comprising an anion exchange membrane to produce a nitrate and a sulfate, and further regenerating the absorbed liquid, wherein the nitrogen oxide and sulfur oxide And a method for simultaneously processing the same.

In another aspect, the present invention relates to a method for producing a scorer comprising: (i) a scrubber containing an absorbent based on iron and ethylenediaminetetraacetic acid and simultaneously absorbing nitrogen oxides and sulfur oxides; (ii) an electrochemical cell having an electrode structure of microvoids regenerating the absorption liquid absorbed in the scrubber; And (iii) an electrochemical cell including an anion exchange membrane for producing nitrate and sulfate in an absorption liquid regenerated in the electrochemical cell. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for simultaneous treatment of nitrogen oxides and sulfur oxides using iron-ethylenediamine tetraacetic acid .

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an apparatus for simultaneously treating nitrogen oxides and sulfur oxides using iron-ethylenediaminetetraacetic acid according to the present invention.

Specifically, FIG. 1 (a) is a scrubber for absorbing exhaust gas. The exhaust gas inlet is typically used in a process of supplying gas to a liquid phase, and is supplied from an exhaust gas generating point using a pump or a venturi .

The inside of the scrubber is filled with a mixture of trivalent and trivalent ethylenediaminetetraacetic acid (pH 6 ~ 8). The concentration of total iron-ethylenediaminetetraacetic acid in the scrubber may range from 0.1M to 1M. Also, the ratio of dihydric iron-ethylenediaminetetraacetic acid in total iron-ethylenediaminetetraacetic acid is maintained at 70 to 90%.

Under the above-mentioned conditions, absorption of nitrogen oxides and sulfur oxides takes place inside the scrubber. Firstly, divalent iron-ethylenediaminetetraacetic acid has a very high adsorptivity to nitrogen monoxide, so it can be absorbed, and sulfuric acid basically dissolves very well in the base. Even if the pH of the scrubber is 7 or less, the solubility is high, so it is relatively easy to absorb. Nitrogen oxides and sulfur oxides absorption reactions are as follows.

Fe ²⁺ -EDTA + NO- > Fe ²⁺ -EDTA-NO

SO ₂ + ₂ OH ^- → SO ₃ ^2- + H ₂ O

In step (a) of the present invention, the sulfur oxides are converted into sulfuric acid by the residual oxygen in the flue gas or tritium-ethylenediamine tetraacetic acid.

The sorbent of step (a) is preferably ammonium iron-ethylenediamine tetraacetic acid (ammonium EDTA) having an ammonium ion as a cation source.

In the present invention, the absorbent may be ammonium iron-ethylenediamine tetraacetic acid (ammonium EDTA) having an ammonium ion as a cation source.

In the present invention, in step (a), the concentration of the absorbent may be 0.1 M to 1 M and the pH may be 6 to 8. [

In the present invention, the ratio of bivalent iron-ethylenediaminetetraacetic acid in the total iron-ethylenediaminetetraacetic acid contained in the absorbent may be 70 to 90%.

1 (b) is a step of flowing the absorption liquid generated in the step (a) through an electrochemical cell having an electrode structure of microvoids and regenerating the absorption liquid. In order to flow the liquid through the microporous electrode structure, the anode is passed first and then the cathode. By sequentially passing through the cathode after the anode, the reaction occurring inside the reactor is as follows.

H ₂ O → _1/2 O ₂ + 2H ⁺ + 2 e ^- (anode reaction)

Fe ²⁺ -EDTA-NO-> Fe ³⁺ -EDTA + e- + NO (anode reaction)

Fe ²⁺ -EDTA-NO + _1/2 O ₂ + 2H ^{+ -} & gt ^; Fe ³⁺ -EDTA + H ₂ O + NO

2NO + O ₂ ? 2NO ₂

3NO ₂ + H ₂ O? 2HNO ₃ + NO

Fe ³⁺ -EDTA + e - > Fe ²⁺ -EDTA (cathode reaction)

Specifically, first, electrochemical oxidation occurs in the anode. When high overvoltage is applied, water is decomposed and oxygen is generated or when dihydric iron-ethylenediaminetetraacetic acid is converted into trivalent iron-ethylenediaminetetraacetic acid and the overvoltage is low. 2 Ferrous Iron-Ethylenediaminetetraacetic acid is a trivalent iron-ethylenediamine Only the reaction that is oxidized to tetraacetic acid occurs. As a result, when the oxidizing atmosphere is maintained, the ratio of trivalent iron-ethylenediaminetetraacetic acid increases, and this form deteriorates the ability of the nitrogen oxide to adsorb the nitrogen oxide, so that the nitrogen oxide is desorbed.

When the overvoltage is low, only desorbed nitrogen oxides can be collected at a high concentration and converted to ammonium nitrate fertilizer by reacting with oxygen, water and ammonia in the general atmosphere. The nitrogen oxide trap is usually used in a process of collecting a general gas, and may further include a pump if necessary.

When the overvoltage is high, the desorbed nitrogen oxide reacts with the oxygen generated by the water decomposition to exist in the form of nitrogen dioxide, and since the nitrogen dioxide reacts with water and is directly converted into the nitrate form, the product is converted only in the solution without generating nitrogen gas

In the step (b), the trivalent iron-ethylenediaminetetraacetic acid is reduced to diacid-ethylenediaminetetraacetic acid to regenerate the absorption liquid.

In operation (b), the anode may be selected from the group consisting of platinum, titanium, or DSA (Dimensionally Stable Anode), or an anode used in a conventional chlor-alkali process may be used as it is have. The cathode may be a noble metal such as platinum, palladium, ruthenium, gold or silver or a transition metal such as manganese, cobalt, nickel, copper or zinc or a cathode used in a conventional chloralkaline process.

In the operation of step (b), when it is desired to collect high purity nitrogen oxide without generating oxygen, it is preferable that the applied voltage is 0.7 V or less, and oxygen is generated and nitrated to nitrate and dissolved in the solution It is preferable that the applied voltage is 1 V or more.

In the electrochemical device of the step (b), the applied voltage is set to 0.1 to 0.7 V and the nitrogen oxide is collected. In the electrochemical device of the step (b), the applied voltage is set to 1 to 10 V And converted into a nitrate to dissolve in the absorption liquid.

1 (c) is a step of separating the nitrate and sulphate formed in steps (a) and (b) using an electrochemical cell including an anion exchange membrane to produce fertilizer and further regenerating the absorption liquid. When an external voltage is applied, the electric field causes the nitrate and sulphate to move from the cathode to the anode through the anion exchange membrane. The anode chamber is continuously supplied with ammonia, and the ammonia acts as a cation source, and the nitrate and sulphate discharged from the cathode serve as an anion source, so that ammonium nitrate and ammonium sulfate fertilizers can be collected as final products. The reactions occurring inside the reactor are as follows.

H ₂ O → _1/2 O ₂ + 2H ⁺ + 2 e ^- (anode reaction)

SO ₃ ^2- + 2OH-? SO ₄ ^2- + 2e ^- + H ₂ O (anode reaction)

Fe ³⁺ -EDTA + e - > Fe ²⁺ -EDTA (cathode reaction)

2H ₂ O + 2e ^- ? H ₂ + 2OH ^- (cathode reaction)

The reaction mainly occurring in the anode of the step (c) is a reaction in which water is decomposed to generate oxygen, or when the entire sulfur oxide is not converted to a sulfate but is present as a partial sulfite during the steps (a) and (b) , The sulfite acts as an electron donor and is oxidized. In the step (c), water is basically decomposed to generate hydrogen, but when trivalent iron-ethylenediaminetetraacetic acid is present in the chamber, it is further converted into divalent iron-ethylenediaminetetraacetic acid, . The solution through the cathode of step (c) can be recycled as the absorbent of step (a).

In operation (c), the anode may be selected from the group consisting of platinum, titanium, or DSA (Dimensionally Stable Anode), or an anode used in a conventional chlor-alkali process may be used as it is have. The cathode may be a noble metal such as platinum, palladium, ruthenium, gold or silver or a transition metal such as manganese, cobalt, nickel, copper or zinc or a cathode used in a conventional chloralkaline process.

In the operation of the step (c), the applied voltage is preferably 1.23 to 5.0 V.

In operation (c), the anion exchange membrane may be a conventional anion exchange membrane as it is. For example, SELEMION AMV, SELEMION AMT, SELEMION DSV, SELEMION AAV, SELEMION ASV, SELEMION AHD, , Neosepta AMX, Fumasep FAS, Fumasep FAB, Fumasep FAD, Fumasep FAP, Fumasep FAA-3, and the like.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereto will be. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (16)

Process for the simultaneous treatment of nitrogen oxides and sulfur oxides with iron-ethylenediamine tetraacetic acid comprising the steps of:
(a) simultaneously absorbing nitrogen oxides and sulfur oxides with an absorbent based on iron and ethylenediaminetetraacetic acid;
(b) regenerating an absorbing solution produced by absorbing nitrogen oxides and sulfur oxides from the absorbent in an electrochemical cell having an electrode structure of micro pores; And
(c) applying the regenerated absorbing solution to an electrochemical cell comprising an anion exchange membrane to produce nitrate and sulfate, and further regenerating the absorbed solution.
The method of claim 1, wherein the sorbent is ammonium iron-ethylenediamine tetraacetic acid (Ammonium iron EDTA) having an ammonium ion as a cation source.
The method according to claim 1, wherein the concentration of the absorbent in step (a) is 0.1M to 1M.
The method of claim 1, wherein the pH of the absorbent is from 6 to 8.
The method of claim 1, wherein the ratio of di-iron-ethylenediaminetetraacetic acid in the total iron-ethylenediaminetetraacetic acid contained in the sorbent is 70-90%.
The electrochemical device according to claim 1, wherein the anode of the electrochemical device is selected from the group consisting of platinum, titanium or a dimensionally stable anode (DSA), and the cathode of the electrochemical device is selected from platinum, palladium, ruthenium, gold, silver, manganese, cobalt , Nickel, copper, iron, and zinc.
The method according to claim 1, wherein the applied voltage is 0.1 to 0.7 V in the electrochemical device of step (b) to collect nitrogen oxide.
The method for simultaneous treatment of nitrogen oxides and sulfur oxides according to claim 1, wherein in the electrochemical device of step (b), the applied voltage is changed from 1 V to 10 V and converted into nitrate to dissolve in the absorption liquid.
The method according to claim 1, wherein the applied voltage in the electrochemical device including the anion exchange membrane in step (c) is 1.23 to 5.0 V.
The anion exchange membrane according to claim 1, wherein the anion exchange membrane used in the electrochemical device including the anion exchange membrane of the step (c) is selected from the group consisting of SELEMION AMV, SELEMION AMT, SELEMION DSV, SELEMION AAV, SELEMION ASV, SELEMION AHD, SELEMION APS4, Neosepta AMX, FAS, Fumasep FAB, Fumasep FAD, Fumasep FAP and Fumasep FAA-3.
An apparatus for simultaneous treatment of nitrogen oxides and sulfur oxides with iron-ethylenediamine tetraacetic acid comprising:
(i) a scrubber containing an absorbent based on iron and ethylenediaminetetraacetic acid, which simultaneously absorbs nitrogen oxides and sulfur oxides;
(ii) an electrochemical cell having an electrode structure of microvoids regenerating the absorption liquid absorbed in the scrubber; And
(iii) an anion exchange membrane for producing nitrate and sulfate in the absorption liquid regenerated in the electrochemical cell.
12. The apparatus of claim 11, wherein the sorbent is ammonium iron-ethylenediamine tetraacetic acid (AMTA) having an ammonium ion as a cation source.
12. The apparatus of claim 11, wherein the concentration of the absorbent is from 0.1M to 1M and the pH is from 6 to 8.
12. The apparatus of claim 11, wherein the ratio of di-iron-ethylenediaminetetraacetic acid in the total iron-ethylenediaminetetraacetic acid contained in the sorbent is 70-90%.
12. The electrochemical device according to claim 11, wherein the anode of the electrochemical device is selected from the group consisting of platinum, titanium or a dimensionally stable anode (DSA), and the cathode of the electrochemical device is selected from the group consisting of platinum, palladium, ruthenium, gold, silver, manganese, , Nickel, copper, iron, and zinc.
12. The anion exchange membrane according to claim 11, wherein the anion exchange membrane used in the electrochemical device includes a membrane selected from the group consisting of SELEMION AMV, SELEMION AMT, SELEMION DSV, SELEMION AAV, SELEMION ASH, SELEMION AHD, SELEMION APS4, Neosepta AMX, Fumasep FAS, , Fumasep FAD, Fumasep FAP and Fumasep FAA-3.

Images