CN102743960B - Preparation method of carbon-based combined electrode, electrolytic tank for decarbonization and desulphurization of flue gas and method for decarbonizing and desulphurizing flue gas on the basis of electrolytic tank - Google Patents

Abstract

The invention provides a method for preparing a carbon-based composite electrode: soaking a carbon-based material in a polytetrafluoroethylene emulsion and then roasting to obtain a carbon-based waterproof material layer; mixing activated carbon, polytetrafluoroethylene emulsion and a noble metal-based catalyst to obtain Catalytic material: coating the catalytic material on the carbon-based waterproof material layer and performing hot pressing to obtain a carbon-based composite electrode. The invention provides an electrolytic cell for decarburization and desulfurization of flue gas, which comprises a DC power supply, a cathode electrode, an anode electrode, an electrolyte and the like. Wherein, the anode electrode is a graphite electrode, and the cathode electrode is a carbon-based composite electrode prepared by the above method. The present invention also provides a method for decarburization and desulfurization of flue gas based on the above-mentioned electrolytic cell: after electrification, the flue gas is passed into the cathode cell for reaction, and then the obtained first reaction product is sent into the anode cell, after the reaction Removes carbon dioxide and sulfur dioxide. The invention does not need to consume chemical substances when decarbonizing and desulfurizing, and is green and clean.

Description

Preparation method of carbon-based composite electrode, electrolytic cell for decarbonization and desulfurization of flue gas, and method for decarbonization and desulfurization of flue gas

technical field

The invention relates to the technical field of flue gas purification, in particular to a method for preparing a carbon-based composite electrode, an electrolytic cell for decarbonizing and desulfurizing flue gas, and a method for decarbonizing and desulfurizing flue gas.

Background technique

Flue gas refers to gaseous substances produced during the combustion of fossil fuels such as coal that are not conducive to environmental protection, and its components include carbon dioxide, sulfur dioxide, and nitrogen oxides. Therefore, the flue gas needs to be purified to meet the emission standards, so as to reduce the pollution to the environment.

In order to achieve the purpose of flue gas desulfurization, it is often necessary to add alkaline substances to absorb sulfur dioxide. Based on this principle, the existing methods for flue gas desulfurization include calcium method based on CaCO ₃ (limestone), magnesium method based on MgO, sodium method based on Na ₂ CO ₃ , and NH ₃ The ammonia method based on the organic alkali method, the organic alkali method based on the organic alkali, etc., such as the Chinese patent document with the authorized announcement number CN100411715C discloses a flue gas wet desulfurization process, which is operated according to the following steps: (1) The hydration absorbent is sprayed into the flue gas from the upper part of the desulfurization tower; (2) The flue gas is in reverse contact with the hydration absorbent in the desulfurization tower, and forms a closer contact with the hydration absorbent in the multi-layer wire mesh area. Contact, so that SO ₂ in the flue gas is transferred to the liquid phase and stored in the hydration absorbent circulation tank at the bottom of the desulfurization tower; (3) The air is dispersed and sent to the hydration absorbent in the upper layer of the above circulation tank, so that it is absorbed The SO ₂ is oxidized to form granular gypsum; and (4) lead out the mixed solution of the hydration absorbent and the gypsum next time in the well-mixed circulation tank, and separate the larger particle gypsum. The hydration absorbent mentioned above can be a suspension made of CaO, CaSO ₄ or MgO, etc. On the other hand, the separation of CO ₂ from flue gas in the prior art also requires the addition of alkaline substances for absorption to generate carbonates or bicarbonates so that CO ₂ can be captured; additional acidic substances and the generated carbonates or bicarbonate to release CO ₂ , allowing it to be recycled.

The above-mentioned methods for decarburization and sulfur removal of flue gas all require the addition of alkaline and acidic chemical substances, resulting in a large amount of material consumption, which is not conducive to environmental protection.

Contents of the invention

In order to solve the above technical problems, the present invention provides a method for preparing a carbon-based composite electrode, an electrolytic cell for decarburization and desulfurization of flue gas, and a method for decarburization and desulfurization of flue gas. There is no need to consume chemicals during carbon desulfurization, which is green and clean.

The invention provides a method for preparing a carbon-based composite electrode, comprising the following steps:

The carbon-based material is soaked in the polytetrafluoroethylene emulsion and then roasted to obtain a carbon-based waterproof material layer;

Mix activated carbon, polytetrafluoroethylene emulsion and noble metal-based catalyst to obtain catalytic material;

The catalytic material is coated on the carbon-based waterproof material layer and then hot-pressed to obtain a carbon-based composite electrode.

The invention provides an electrolytic cell for decarburization and desulfurization of flue gas, comprising:

DC power supply;

A cathode cell in which the cathode electrode is connected to the negative pole of the DC power supply through a wire, and the cathode electrode is a carbon-based composite electrode;

The anode electrode is connected to the positive pole of the DC power supply through a wire, and the anode cell is separated from the cathode cell by an ion exchange membrane, and the anode electrode is a graphite electrode;

an electrolyte disposed within said cathodic cell and said anode cell;

The preparation method of the carbon-based composite electrode comprises the following steps:

The carbon-based material is soaked in the polytetrafluoroethylene emulsion and then roasted to obtain a carbon-based waterproof material layer;

Mix activated carbon, polytetrafluoroethylene emulsion and noble metal-based catalyst to obtain catalytic material;

The catalytic material is coated on the carbon-based waterproof material layer and then hot-pressed to obtain a carbon-based composite electrode.

Preferably, in the preparation method of the carbon-based composite electrode, the temperature of the calcination is 300° C. to 500° C., and the calcination time is 5 hours to 10 hours.

Preferably, in the preparation method of the carbon-based composite electrode, when the activated carbon, the polytetrafluoroethylene emulsion and the noble metal-based catalyst are mixed, the mass ratio of the activated carbon, the polytetrafluoroethylene emulsion and the noble metal-based catalyst is For (4~5):(2~3):1.

Preferably, the noble metal-based catalyst is a platinum-based catalyst, a ruthenium-based catalyst or a palladium-based catalyst, and the electrolyte is a sulfate solution.

The present invention provides a method for decarburization and desulfurization of flue gas based on the electrolytic cell described above, comprising the following steps:

Turn on the DC power supply, pass the flue gas into the cathode cell for reaction, and obtain the first reaction product;

The first reaction product enters the anode cell through the ion exchange membrane for reaction to remove carbon dioxide and sulfur dioxide in the flue gas.

Preferably, the current density of the DC power supply is 5mA/cm ² -50mA/cm ² .

Preferably, the potential of the carbon-based composite electrode is 0.2V-1.2V, and a saturated calomel electrode is used as a reference electrode.

Preferably, the area of the cathode electrode is 3cm ² ~5cm ² , and the flow rate of the flue gas is 200mL/min~400mL/min.

Preferably, the flue gas is dust-removed and denitrified flue gas.

Compared with the prior art, the method provided by the present invention adopts the above-mentioned electrolytic cell to decarburize and desulfurize the flue gas. In this method, the DC power supply is first turned on, and the flue gas is passed into the cathode cell for reaction to obtain the first A reaction product, and then the first reaction product enters the anode cell through the ion exchange membrane for reaction to remove carbon dioxide and sulfur dioxide in the flue gas. In the present invention, the flue gas is passed into the cathode pool, reacts with the alkaline substance produced by the electrochemical reaction in the cathode pool, and then reacts the first reaction product obtained with the acidic substance in the anode pool, thereby removing the flue gas sulfur dioxide and carbon dioxide in the air. The invention separates and captures the sulfur dioxide and carbon dioxide in the flue gas with alkaline substances and acidic substances produced by an electrochemical method, so as to purify the flue gas. The invention consumes electric energy during decarbonization and desulfurization, does not need to consume chemical substances, has the characteristics of green cleanness and no secondary pollution, and has broad application prospects.

Description of drawings

Fig. 1 is a schematic diagram of the working principle of an electrolytic cell for decarbonizing and desulfurizing flue gas provided by an embodiment of the present invention.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than limiting the claims of the present invention.

The invention provides a method for preparing a carbon-based composite electrode, comprising the following steps:

The carbon-based material is soaked in the polytetrafluoroethylene emulsion and then roasted to obtain a carbon-based waterproof material layer;

Mix activated carbon, polytetrafluoroethylene emulsion and noble metal-based catalyst to obtain catalytic material;

The catalytic material is coated on the carbon-based waterproof material layer and then hot-pressed to obtain a carbon-based composite electrode.

In the invention, the carbon-based material is used as an electrode substrate, and a catalytic material containing a noble metal-based catalyst is added to prepare a carbon-based composite electrode. When it is assembled into an electrolytic cell, it can realize the efficient reduction of oxygen, and obtain acidic and alkaline substances, which can be used for decarbonization and desulfurization of flue gas.

In the present invention, the carbon-based material is first subjected to hydrophobic treatment, specifically: the carbon-based material is infiltrated with a polytetrafluoroethylene emulsion, and then roasted to obtain a carbon-based waterproof material layer.

The present invention has no special limitation on the carbon-based material, and carbon cloth commonly used in the field can be used. The present invention has no special restrictions on the polytetrafluoroethylene emulsion, and the polytetrafluoroethylene emulsion commonly used in this field can be used, such as a polytetrafluoroethylene emulsion with a solid content of 30% to 40%, to form the polytetrafluoroethylene emulsion. The surfactant of the emulsion is a commonly used dispersant in the field; the amount of the polytetrafluoroethylene emulsion is the amount that can soak the carbon-based material. In the present invention, the calcination temperature is preferably 300°C-500°C, more preferably 350°C-450°C; the calcination time is preferably 5 hours-10 hours, more preferably 7 hours-9 hours.

The invention mixes the activated carbon, the polytetrafluoroethylene emulsion and the noble metal-based catalyst to obtain the catalytic material.

When mixing, the mass ratio of the activated carbon, the polytetrafluoroethylene emulsion and the noble metal-based catalyst is preferably (4~5):(2~3):1, more preferably 4:2:1 or 5: 3:1. The present invention has no special limitation on the activated carbon, and the activated carbon commonly used in this field can be used. The polytetrafluoroethylene emulsion is preferably the same as the polytetrafluoroethylene emulsion used for the above-mentioned hydrophobic treatment. The noble metal-based catalyst has a high-efficiency catalytic effect, and the present invention has no special limitation on it, and a noble metal-based catalyst commonly used in the field can be used, preferably a platinum-based catalyst, a ruthenium-based catalyst or a palladium-based catalyst. The present invention has no particular limitation on the temperature and time of the mixing.

After the carbon-based waterproof material layer and the catalytic material are obtained, the present invention coats the catalytic material on the carbon-based waterproof material layer, forms a catalytic material layer on the surface, and performs hot pressing to obtain a carbon-based composite electrode after molding.

In the present invention, the temperature of the hot pressing is preferably 80°C~110°C, more preferably 90°C~100°C; the pressure of the hot pressing is preferably 0.2MPa~0.5MPa, more preferably 0.3MPa~0.4MPa . Before hot pressing, the thickness ratio of the catalytic material layer to the carbon-based waterproof material layer is preferably 1:5-10, more preferably 1:8-9. The present invention has no special limitation on the area of the carbon-based composite electrode, which can be determined according to actual needs, for example, the area of the carbon-based composite electrode is 3 cm ² ~5 cm ² .

The invention provides an electrolytic cell for decarburization and desulfurization of flue gas, comprising:

DC power supply;

A cathode cell in which the cathode electrode is connected to the negative pole of the DC power supply through a wire, and the cathode electrode is a carbon-based composite electrode;

The anode electrode is connected to the positive pole of the DC power supply through a wire, and the anode cell is separated from the cathode cell by an ion exchange membrane, and the anode electrode is a graphite electrode;

an electrolyte disposed within said cathodic cell and said anode cell;

The preparation method of the carbon-based composite electrode comprises the following steps:

The carbon-based material is soaked in the polytetrafluoroethylene emulsion and then roasted to obtain a carbon-based waterproof material layer;

Mix activated carbon, polytetrafluoroethylene emulsion and noble metal-based catalyst to obtain catalytic material;

The catalytic material is coated on the carbon-based waterproof material layer and then hot-pressed to obtain a carbon-based composite electrode.

In the present invention, the carbon-based composite electrode prepared by the above-mentioned preparation method is used as the cathode electrode of the cathode cell, and the graphite electrode is used as the anode electrode of the anode cell, and the cathode cell and the anode cell are separated by an ion exchange membrane and connected to a direct current After the power supply and the electrolyte are added, an electrolytic cell is assembled to form an electrolytic cell, which can be used for decarbonization and sulfur removal of flue gas, which is beneficial to environmental protection.

In the electrolytic cell, the present invention has no special restrictions on the DC power supply, the graphite electrode, the ion exchange membrane, the electrolyte solution and the wire, and those commonly used in the field can be used. The electrolyte is preferably a sulfate solution, such as a sodium sulfate solution with a concentration of 1 mol/L to 2 mol/L.

In the electrolytic cell, the cathode electrode is a carbon-based composite electrode prepared by the above-mentioned preparation method, which can realize efficient reduction of oxygen and obtain acidic and alkaline substances to remove carbon and sulfur in the flue gas . The preparation method of the carbon-based composite electrode is the same as that described above, and will not be repeated here.

Referring to FIG. 1 , FIG. 1 is a schematic diagram of the working principle of an electrolytic cell for decarbonizing and desulfurizing flue gas provided by an embodiment of the present invention.

Turn on the DC power supply, oxygen or air is passed into the cathode cell, and a reduction reaction occurs on the cathode electrode to generate hydroxide ions, which is to obtain alkaline substances; while in the anode cell, the anode water is oxidized to oxygen and obtains hydrogen ions, which is to generate Acidic substances. Under the condition of electrification, the alkaline substances and acidic substances produced by the electrolytic cell can be used to supply the acid and alkali used in the flue gas decarbonization and sulfur removal process.

Based on the electrolytic cell described above, the present invention also provides a method for decarburization and desulfurization of flue gas, comprising the following steps:

Turn on the DC power supply, pass the flue gas into the cathode cell for reaction, and obtain the first reaction product;

The first reaction product enters the anode cell through the ion exchange membrane for reaction to remove carbon dioxide and sulfur dioxide in the flue gas.

The present invention uses the above-mentioned electrolytic cell to decarbonize and desulfurize the flue gas, and the content of the electrolytic cell is the same as the above-mentioned content, and will not be repeated here. The present invention separates and captures sulfur dioxide and carbon dioxide in the flue gas with alkaline substances and acidic substances produced by an electrochemical method to purify the flue gas, consumes only electric energy and does not need to consume chemical substances, and is green, clean, and secondary-free characteristics of pollution.

In the invention, the DC power supply is first turned on, and the flue gas is passed into the cathode pool for reaction to obtain the first reaction product.

In the present invention, the current density of the DC power supply is preferably 5mA/cm ² ~50mA/cm ² , which can make the pH of the electrolytic cell reach 2~11; since the content of sulfur dioxide in the flue gas is low, when mainly removing sulfur dioxide , the current density can be 5mA/cm ² ~20mA/cm ² ; due to the high content of carbon dioxide in the flue gas, when carbon dioxide is mainly removed, the current density can be 20mA/cm ² ~50mA/cm ² . With the saturated calomel electrode as the reference electrode, the potential of the carbon-based composite electrode is preferably 0.2V~1.2V (vsSCE), more preferably 0.5V~1.0V (vsSCE), which can generate a sufficient amount of alkaline substances And acidic substances, which are beneficial to decarbonization and sulfur removal. The present invention has no special limitation on the flow rate of the flue gas, the area of the cathode electrode is preferably 3cm ² ~5cm ² , the flow rate of the flue gas is preferably 200mL/min~400mL/min, more preferably 250mL/min min~350mL/min. The flue gas is preferably the flue gas after dedusting and denitrification, with less impurities and less impact on decarbonization and sulfur removal. The first reaction product is sulfate and/or carbonate.

After the first reaction product is obtained, the present invention enters the anode cell through the ion exchange membrane for reaction to generate bisulfate and/or carbon dioxide gas, separate and capture sulfur dioxide and carbon dioxide, thereby removing carbon dioxide and carbon dioxide in the flue gas. Sulfur dioxide, cleaning flue gas.

In the present invention, the flue gas is passed into the cathode pool, reacts with the alkaline substance produced by the electrochemical reaction in the cathode pool, and then reacts the first reaction product obtained with the acidic substance in the anode pool, thereby removing the flue gas sulfur dioxide and carbon dioxide in the air. The invention separates and captures the sulfur dioxide and carbon dioxide in the flue gas with alkaline substances and acidic substances produced by an electrochemical method, so as to purify the flue gas. The invention consumes electric energy during decarbonization and desulfurization, does not need to consume chemical substances, has the characteristics of green cleanness and no secondary pollution, and has broad application prospects.

It can be seen from the infrared detection commonly used in this field that the removal efficiency of the present invention for carbon dioxide in flue gas is above 99%, and the removal efficiency of sulfur dioxide is above 98%.

In order to further understand the present invention, the preparation method of the carbon-based composite electrode provided by the present invention, the electrolytic cell for decarbonizing and desulfurizing flue gas and the method for decarbonizing and desulfurizing flue gas provided by the present invention will be specifically described below in conjunction with examples.

Example 1

Soak the carbon cloth in the polytetrafluoroethylene emulsion and bake it at 300°C to obtain a carbon cloth waterproof layer after 10 hours; according to the mass ratio of 5:3:1, mix activated carbon, polytetrafluoroethylene emulsion and platinum-based catalyst to obtain Catalytic material: coating the catalytic material on the carbon cloth layer, and then performing hot pressing at a temperature of 80° C. and a pressure of 0.5 MPa to obtain a carbon-based composite electrode.

Assembling the carbon-based composite electrode into an electrolytic cell for flue gas decarbonization and desulfurization, the electrolytic cell includes: a DC power supply; a cathode cell in which the carbon-based composite electrode is connected to the negative pole of the DC power supply through a wire; graphite The electrode is connected to the positive pole of the DC power supply through a wire, and the anode pool is separated from the cathode pool by an ion exchange membrane; a sodium sulfate solution with a concentration of 1mol/L.

Turn on the DC power supply, control the current density to 15mA/cm ² , control the potential of the carbon-based composite current to 0.5V (vs SCE), and pass the flue gas after dust removal and denitrification into the cathode pool at a flow rate of 300mL/min. reaction to generate sulfate and carbonate; the sulfate and carbonate enter the anode cell through the ion exchange membrane for reaction to obtain bisulfate and carbon dioxide gas, and remove sulfur dioxide and carbon dioxide in the flue gas. The removal efficiency of carbon dioxide is above 99%, and the removal efficiency of sulfur dioxide is above 98%.

Example 2

After the carbon cloth is soaked in the polytetrafluoroethylene emulsion, it is baked at 500°C, and the carbon cloth waterproof layer is obtained after 5 hours; according to the mass ratio of 4:2:1, the activated carbon, the polytetrafluoroethylene emulsion and the platinum-based catalyst are mixed to obtain Catalytic material: coating the catalytic material on the carbon cloth layer, and then performing hot pressing at a temperature of 110° C. and a pressure of 0.2 MPa to obtain a carbon-based composite electrode.

Assembling the carbon-based composite electrode into an electrolytic cell for flue gas decarbonization and desulfurization, the electrolytic cell includes: a DC power supply; a cathode cell in which the carbon-based composite electrode is connected to the negative pole of the DC power supply through a wire; graphite The electrode is connected to the positive pole of the DC power supply through a wire, and the anode pool is separated from the cathode pool by an ion exchange membrane; a sodium sulfate solution with a concentration of 1mol/L.

Turn on the DC power supply, control the current density to 50mA/cm ² , control the potential of the carbon-based composite current to 1.2V (vs SCE), and pass the flue gas after dust removal and denitrification into the cathode pool at a flow rate of 300mL/min. reaction to generate sulfate and carbonate; the sulfate and carbonate enter the anode cell through the ion exchange membrane for reaction to obtain bisulfate and carbon dioxide gas, and remove sulfur dioxide and carbon dioxide in the flue gas. The removal efficiency of carbon dioxide is above 99%, and the removal efficiency of sulfur dioxide is above 98%.

It can be seen from the above examples that the present invention separates and captures sulfur dioxide and carbon dioxide in the flue gas with alkaline substances and acidic substances produced by electrochemical methods, so as to purify the flue gas without material consumption and is green and clean.

The descriptions of the above embodiments are only used to help understand the method and core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (9)

1., for a preparation method for the carbon-based composite electrode of the electrolytic cell of flue gas decarbonization, desulfuration, comprise the following steps:

Carry out roasting after carbon-based material being infiltrated ptfe emulsion, obtain carbon back waterproof layer;

Active carbon, ptfe emulsion and noble metal-based catalysts are mixed, obtains catalysis material; The mass ratio of described active carbon, described ptfe emulsion and described noble metal-based catalysts is (4 ~ 5): (2 ~ 3): 1;

Described catalysis material is coated on described carbon back waterproof layer, after its surface forms cati material, carries out hot pressing, obtain carbon-based composite electrode; The Thickness Ratio of described catalyst layer and described carbon back waterproof layer is 1:5 ~ 10;

The area of described carbon-based composite electrode is 3cm ²~ 5cm ².

2., for an electrolytic cell for flue gas decarburization sulphur removal, comprising:

Dc source;

The cathode pool that cathode electrode is connected with described DC power cathode by wire, described cathode electrode is carbon-based composite electrode;

The anode pool that anode electrode is connected with described DC power anode by wire, separated by amberplex and described cathode pool, described anode electrode is graphite electrode;

Be placed in the electrolyte in described cathode pool and described anode pool;

The preparation method of described carbon-based composite electrode comprises the following steps:

Carry out roasting after carbon-based material being infiltrated ptfe emulsion, obtain carbon back waterproof layer;

Active carbon, ptfe emulsion and noble metal-based catalysts are mixed, obtains catalysis material; The mass ratio of described active carbon, described ptfe emulsion and described noble metal-based catalysts is (4 ~ 5): (2 ~ 3): 1;

Described catalysis material is coated on described carbon back waterproof layer, after its surface forms cati material, carries out hot pressing, obtain carbon-based composite electrode; The Thickness Ratio of described catalyst layer and described carbon back waterproof layer is 1:5 ~ 10;

The area of described carbon-based composite electrode is 3cm ²~ 5cm ².

3. electrolytic cell according to claim 2, is characterized in that, in the preparation method of described carbon-based composite electrode, the temperature of described roasting is 300 DEG C ~ 500 DEG C, and the time of described roasting is 5 hours ~ 10 hours.

4. electrolytic cell according to claim 2, is characterized in that, described noble metal-based catalysts is platinum based catalyst, ruthenium-based catalyst or palladium-based catalyst, and described electrolyte is sulfate liquor.

5. based on the electrolytic cell described in any one of claim 2 ~ 4 to a method for flue gas decarburization sulphur removal, comprise the following steps:

Open dc source, flue gas is passed into cathode pool and reacts, obtain the first product;

Described first product is entered anode pool via amberplex react, remove the carbon dioxide in described flue gas and sulfur dioxide.

6. method according to claim 5, is characterized in that, the current density of described dc source is 5mA/cm ²~ 50mA/cm ².

7. method according to claim 5, is characterized in that, the current potential of described carbon-based composite electrode is 0.2V ~ 1.2V, take saturated calomel electrode as reference electrode.

8. method according to claim 5, is characterized in that, the area of described cathode electrode is 3cm ²~ 5cm ², the flow velocity of described flue gas is 200mL/min ~ 400mL/min.

9. method according to claim 5, is characterized in that, described flue gas is the flue gas after dedusting, denitration.