SO3 Adsorbent, Its Preparation Method and Application

Abstract

This application belongs to the field of flue gas treatment, and provides an SO3 adsorbent, a preparation method thereof and an application. The SO3 adsorbent of this application includes activated carbon and an olefin-carbon mixture loaded thereon, wherein the olefin-carbon mixture includes graphene oxide modified with alkanolamine and carbon nanotubes. The SO3 adsorbent can effectively remove SO3 in flue gas, and is particularly suitable for treating flue gas with high concentration of SO3.

Description

Technical Field

[0001] This application belongs to the field of flue gas treatment. Specifically, a SO3 adsorbent, its preparation method and application are provided. Background Art

[0002] As a power plant pollutant, the emission of SO3 not only damages boiler equipment, but also poses a threat to the ecological environment and even survival safety. Therefore, the emission control of SO3 has received increasing attention. High-temperature combustion in the furnace and selective catalytic reduction (SCR) catalytic oxidation of part of SO2 are the main reasons for the generation of SO3. When burning high-sulfur coal, the SO3 concentration in the flue gas at the SCR outlet can reach 100 mg / m 3 or even higher. Although devices such as electrostatic precipitators and wet electrostatic precipitators in power plants can effectively remove SO3 to avoid discharging it into the atmosphere, high concentrations of SO3 and H2SO4 vapor in the flue gas will cause serious damage to equipment, resulting in blockage of SCR catalysts and air preheaters, inactivation of SCR catalysts, corrosion of downstream pipelines and equipment, and even corrosion of concrete and plastic parts in the plant building. Therefore, reducing the SO3 concentration in the flue gas is also of great significance for the stable operation of the coal-fired system. With the implementation of ultra-low emission transformation in thermal power plants, the emissions of SO2, NOx and soot have been effectively controlled, and the emission control of the unconventional pollutant SO3 will become the focus of air pollutant treatment in the next stage.

[0003] In addition, due to the general increase in spare layer adsorbents during the ultra-low emission transformation of coal-fired power plants, the increase in the SO2 / SO3 conversion rate increases the concentration of SO3 downstream of denitrification, resulting in further aggravation of the corrosion and blockage problems caused by the corresponding SO3 or NH4HSO4 (formed by the reaction of escaped NH3 in the flue gas with SO3) and the pollution problems after emission, which also brings new challenges to the control of SO3 pollutants in coal-fired power plants. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, the purpose of this application is to provide a SO3 adsorbent, its preparation method and application. The SO3 adsorbent of this application can effectively remove SO3 in the flue gas, and is especially suitable for treating flue gas with high concentration of SO3.

[0005] In the first aspect, this application provides a SO3 adsorbent, which includes activated carbon and an olefin-carbon mixture loaded thereon, wherein the olefin-carbon mixture includes graphene oxide modified with alkanolamine and carbon nanotubes.

[0006] In the SO3 adsorbent provided in the present application, the activated carbon has a developed pore structure. Using activated carbon as a carrier is beneficial to reducing the cost of the adsorbent and realizing the industrial production and application of the adsorbent. Loading amine-modified graphene oxide and carbon nanotubes on the activated carbon can significantly improve the adsorption capacity of the activated carbon for SO3; wherein, the hydroxyl group (-OH) on the surface of the amine-modified graphene oxide can form a hydrogen bond with SO3, and the alkaline amine has a strong affinity for acidic SO3, and the carbon nanotube has a more uniform structure at the atomic scale, which can provide the adsorbent with clear adsorption sites and strong van der Waals binding energy, and improve the bonding strength between the amine-modified graphene oxide and the activated carbon, avoiding the "powdering" phenomenon of the adsorbent caused by the flow of flue gas, so that the SO3 adsorbent maintains a high SO3 removal efficiency during long-term flue gas treatment.

[0007] In some embodiments of the present application, the alcoholamine-modified graphene oxide is at least one of monoethanolamine-modified graphene oxide, diethanolamine-modified graphene oxide, and triethanolamine-modified graphene oxide.

[0008] Furthermore, the alcoholamine-modified graphene oxide is diethanolamine-modified graphene oxide. In this case, the adsorbent has stronger alkalinity, which can further improve the adsorption efficiency of SO3.

[0009] In some embodiments of the present application, the iodine value of the activated carbon is not less than 800 mg / g, and the specific surface area is 500 to 1500 m 2 / g, particle size is 3 to 9 mm.

[0010] In some embodiments of the present application, the mass ratio of the activated carbon to the olefin-carbon mixture is 100:(0.2-2). Thus, the adsorbent can maintain a relatively high adsorption capacity for SO3: if the loading of the olefin-carbon mixture is too low, the improvement in the adsorption capacity of the activated carbon is limited, while if the loading is too high, the pores of the activated carbon may be clogged.

[0011] Furthermore, the mass ratio of the activated carbon to the olefin-carbon mixture is 100:(0.3-1).

[0012] In some embodiments of the present application, the mass ratio of the alcoholamine-modified graphene oxide to the carbon nanotubes is (1-4): 1. In this case, the adsorbent "dusting" caused by too low a carbon nanotube content can be avoided as much as possible, and the reduction in removal efficiency that may be caused by too much carbon nanotube content can be suppressed.

[0013] Furthermore, the mass ratio of the alcoholamine-modified graphene oxide to the carbon nanotubes is (1.5-3):1.

[0014] Second aspect, the present application provides a method for preparing the SO3 adsorbent described in the first aspect of the present application, the method comprising:

[0015] (1) Uniformly dispersing graphene oxide and carbon nanotubes in a solvent to obtain a graphene-carbon dispersion;

[0016] (2) Mixing the graphene-carbon dispersion with an activator and performing a first ultrasonic treatment to activate the graphene oxide and carbon nanotubes to obtain a reaction solution;

[0017] (3) Mixing the reaction solution, an alcohol amine and activated carbon and performing a second ultrasonic treatment to modify the activated graphene oxide with the alcohol amine to form alcohol amine-modified graphene oxide, obtaining a mixed solution;

[0018] (4) Performing solid-liquid separation, washing and drying on the mixed solution to obtain the SO3 adsorbent.

[0019] The method provided by the present application can promote the uniform dispersion of the graphene-carbon mixture and load it onto the inner surface of the pores of the activated carbon, obtaining an adsorbent with a uniform distribution of the graphene-carbon mixture on the carrier activated carbon. Specifically, compared with directly modifying the activated carbon by impregnating the alcohol amine-modified graphene oxide and carbon nanotubes, in the present application, the graphene oxide and carbon nanotubes are first dispersed in a solvent and activated together, and the alcohol amination modification of the graphene oxide is carried out in situ in the presence of the activated carbon. This method can improve the uniformity of the loading of the graphene-carbon mixture on the activated carbon and avoid the blockage of the pores of the activated carbon caused by directly adding the alcohol amine-modified graphene oxide and carbon nanotubes with poor water solubility.

[0020] In some embodiments of the present application, in step (1), the oxygen content of the graphene oxide is 35-45%.

[0021] In some embodiments of the present application, in step (1), the diameter of the carbon nanotubes is 2-4 nm, the length is not less than 500 μm, and the specific surface area is not less than 450 m 2 / g.

[0022] In some embodiments of the present application, in step (1), the solid content of the graphene-carbon dispersion is 1-5 mg / mL, and the solvent is water.

[0023] In some embodiments of the present application, in step (2), the activator is potassium hydroxide, and the dosage of potassium hydroxide is 2-3 g relative to 1 L of the graphene-carbon dispersion.

[0024] In some embodiments of the present application, the temperature of the first ultrasonic treatment is 20-40 °C, and the treatment time is 10-60 min.

[0025] In some embodiments of the present application, in step (3), the alkanolamine is at least one of monoethanolamine, diethanolamine, and triethanolamine, preferably diethanolamine.

[0026] In some embodiments of the present application, in step (3), the temperature of the second ultrasonic treatment is 70 - 90 °C, and the treatment time is 2 - 6 h.

[0027] In some embodiments of the present application, in step (3), relative to 1 L of the dispersed carbon olefin liquid, the dosage of the activated carbon is 0.1 - 0.3 kg, and the dosage of the alkanolamine is 60 - 110 mL.

[0028] In some embodiments of the present application, in step (4), the solid-liquid separation method includes screen filtration, and the solvent used for washing is water.

[0029] In some embodiments of the present application, in step (4), the drying temperature is 100 - 300 °C, and the drying time is 2 - 12 h.

[0030] In a third aspect, the present application provides the use of the SO3 adsorbent described in the first aspect of the present application in flue gas desulfurization of SO3.

[0031] In some embodiments of the present application, this use includes: introducing the flue gas to be treated into a fixed-bed device filled with the SO3 adsorbent, so that the flue gas to be treated contacts the SO3 adsorbent to obtain the desulfurized flue gas.

[0032] Further, the concentration of the SO3 adsorbent in the flue gas to be treated is not less than 100 mg / m 3 .

[0033] Further, relative to 1 kg of the SO3 adsorbent, the dosage of the flue gas to be treated is 100 - 600 m 3 , and the temperature of the flue gas to be treated is 60 - 200 °C.

[0034] The additional aspects and advantages of the present application will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present application. Specific Embodiments

[0035] The embodiments of the present application are described in detail below. The described embodiments are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application.

[0036] The "range" disclosed in the present application is defined in the form of a lower limit and / or an upper limit. A given range is defined by selecting a lower limit and / or an upper limit. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range not explicitly recorded, and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, each separately disclosed point or single value itself can be used as a lower limit or an upper limit to be combined with any other point or single value or with other lower limits or upper limits to form a range not explicitly recorded.

[0037] If there is no special instruction, all the embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of the present application.

[0038] Traditional SO3 adsorbents are divided into alkaline adsorbents (such as NaHSO3, NaCO3, natural soda, etc.), activated carbon, etc. Alkaline adsorbents only have an adsorption effect on low-concentration SO3, and the removal efficiency of SO3 is relatively low. Activated carbon is usually used for the adsorption of SO2. Although it also has a certain adsorption capacity for SO3, its adsorption efficiency is too low. Related technologies mention using metal halides and alkali metal hydroxides to modify activated carbon to improve the adsorption capacity of activated carbon for SO3. However, the initial concentration of SO3 in the flue gas treated by the modified activated carbon obtained by this method is not higher than 50mg / m 3 , and the removal efficiency of SO3 decreases significantly after 10 minutes of adsorption treatment, and it cannot be effectively used in the treatment process of high-concentration SO3 flue gas.

[0039] Accordingly, a first aspect of the present application provides an SO3 adsorbent, including activated carbon and an ene-carbon mixture supported thereon, and the ene-carbon mixture includes graphene oxide modified with alkanolamine and carbon nanotubes.

[0040] According to the present application, the activated carbon can be selected from various activated carbons for waste gas adsorption, such as wood-based activated carbon, coconut shell activated carbon or coal-based activated carbon. The shape of the activated carbon can be granular or columnar, and the particle size of the activated carbon can usually be 1-10mm. It should be understood that the particle size of the columnar activated carbon refers to the diameter (φ) of the column body.

[0041] In some embodiments, the iodine value of the activated carbon is not less than 800mg / g, such as ≥800mg / g, ≥900mg / g, ≥1000mg / g, etc., and further can be selected from 800-1200mg / g, such as between 800-900mg / g, between 1000-1100mg / g, etc.; the specific surface area of the activated carbon can be 500-1500m2 / g, such as 600 m 2 / g, 700 m 2 / g, 900 m 2 / g, 950 m 2 / g, 1000 m 2 / g, 1200 m 2 / g, etc.; the particle size of the activated carbon is 3 - 9 mm, such as 3 mm, 4 mm, 5 mm, 5.5 mm, 7 mm, etc. Thus, while improving the adsorption effect on SO3, the adsorbent meets the requirements of industrial application.

[0042] As a preferred example, the activated carbon is columnar coal-based activated carbon. In addition, the columnar coal-based activated carbon can be obtained by commercial purchase, such as a series of columnar coal-based activated carbons with a diameter of 3 - 9 mm and a specific surface area of 780 - 1100 m 2 / g selected from Ningxia Tingyuan Fruit Wood Energy Technology Co., Ltd.

[0043] According to the present application, the ene-carbon mixture is specifically loaded on the surface of the pore structure of the activated carbon, which can effectively improve the adsorption capacity for SO3. Among them, the alcoholamine-modified graphene oxide can be a product formed by the ring-opening reaction of the amino group and amine group in the alcoholamine with the epoxy group provided by graphene oxide. This reaction realizes the immobilization of the alcoholamine on graphene oxide and introduces hydroxyl groups (-OH). The introduction of carbon nanotubes not only provides more adsorption sites but also improves the binding strength between the activated carbon and the alcoholamine-modified graphene oxide.

[0044] In some embodiments, the alcoholamine-modified graphene oxide is at least one of monoethanolamine-modified graphene oxide, diethanolamine-modified graphene oxide, and triethanolamine-modified graphene oxide. Preferably, the alcoholamine-modified graphene oxide is diethanolamine-modified graphene oxide.

[0045] In addition, the alcoholamine-modified graphene oxide can be synthesized by reacting the alcoholamine and the activated graphene oxide in the presence of water at a high temperature (such as 70 - 90 °C). The specific method is as described in the second aspect of the present application and will not be elaborated here.

[0046] According to some embodiments, the mass ratio of the activated carbon to the ene-carbon mixture is 100∶(0.2 - 2), such as 100∶0.3, 100∶0.4, 100∶0.5, 100∶0.7, 100∶1, 100∶1.5, etc. Preferably, the mass ratio of the activated carbon to the ene-carbon mixture is 100∶(0.3 - 1).

[0047] In some embodiments, in the ene-carbon mixture, the mass ratio of the alcohol amine-modified graphene oxide to the carbon nanotubes is (1-4):1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 4:1, etc. Preferably, the mass ratio of the alcohol amine-modified graphene oxide to the carbon nanotubes is (1.5-3):1.

[0048] In the present application, the component content can be calculated based on the feeding amount of each component in the adsorbent, wherein the amount of the alcohol amine-modified graphite oxide is calculated based on graphene oxide.

[0049] The second aspect of the present application provides a method for preparing the SO3 adsorbent described in the first aspect of the present application, and the method includes:

[0050] (1) Disperse graphene oxide (GO) and carbon nanotubes (CNTs) uniformly in a solvent to obtain an ene-carbon dispersion;

[0051] (2) Mix the ene-carbon dispersion with an activator and perform a first ultrasonic treatment to activate the graphene oxide and the carbon nanotubes to obtain a reaction solution;

[0052] (3) Mix the reaction solution, an alcohol amine, and activated carbon and perform a second ultrasonic treatment to modify the activated graphene oxide with the alcohol amine to form alcohol amine-modified graphene oxide to obtain a mixed solution;

[0053] (4) Perform solid-liquid separation, washing, and drying on the mixed solution to obtain the SO3 adsorbent.

[0054] According to the present application, in step (1), in order to improve the mixing uniformity and stability of the ene-carbon dispersion, it is preferred to disperse graphene oxide and carbon nanotubes in a solvent by using a high-pressure homogenizer, and the dispersion can be carried out, for example, at room temperature. As some examples, the operating pressure of the high-pressure homogenizer is not less than 100 MPa, such as 100 MPa, 120 MPa. In addition, the number of times of homogeneous dispersion can be 2-5 times, such as 2 times, 3 times, 4 times, etc. By performing multiple homogeneous dispersions, the possibility of solid particles agglomerating can be reduced, and an ene-carbon dispersion with a nanoscale (D 50 <1 μm) can be obtained.

[0055] In step (1), the graphene oxide as a raw material not only has a high specific surface area but also contains a large number of oxygen-containing functional groups (such as epoxy groups, carboxyl groups, etc.). The oxygen-containing functional groups provide reaction sites for the graphene oxide, which is beneficial to realizing the alcohol amine modification of the graphene oxide. According to some embodiments, the oxygen content of the graphene oxide is 35-45%, such as 35%, 38%, 40%, 41%, 42%, 45%, etc. The oxygen content can be measured by X-ray photoelectron spectroscopy (XPS).

[0056] In step (1), the graphene oxide can be obtained, for example, by a method well-known in the art, such as the Hummers method.

[0057] In some embodiments, the diameter of the carbon nanotubes as raw materials can be 2 - 4 nm, the length is not less than 500 μm, and the specific surface area is not less than 450 m 2 / g. Thus, the bonding strength between the graphene-carbon mixture and the activated carbon can be further improved.

[0058] In some embodiments, the solid content of the graphene-carbon dispersion (i.e., the total content of GO and CNTs) can be 1 - 5 mg / mL, such as 1 mg / mL, 2 mg / mL, 3 mg / mL, etc.

[0059] In some embodiments, in the graphene-carbon dispersion, the mass ratio of the graphene oxide to the carbon nanotubes is (1 - 4):1, such as 1:1, 2:1, 2.5:1, 3:1, 4:1, etc. Preferably, the mass ratio of the graphene oxide to the carbon nanotubes is (1.5 - 3):1.

[0060] According to the present application, in step (2), through the activation treatment, the chemical activity on the surface of the carbon materials (GO, CNTs) can be increased, promoting the formation of a large number of micropores and mesopores in the carbon materials, and further improving the specific surface area of the carbon materials.

[0061] In some embodiments, the activator is potassium hydroxide (KOH). For 1 L of the graphene-carbon dispersion, the dosage of potassium hydroxide is 2 - 3 g, such as 2.1 g, 2.2 g, 2.3 g, 2.2 g, 2.4 g, 2.8 g, etc.

[0062] In some embodiments, the temperature of the first ultrasonic treatment can be 20 - 40 °C, such as 25 °C, 28 °C, 30 °C, etc.; the time of the first ultrasonic treatment can be 10 - 60 min, such as 20 min, 30 min, 35 min, 50 min, 60 min, etc.

[0063] As some examples, the frequency of the first ultrasonic treatment can be 30 - 50 kHz, such as 40 kHz.

[0064] According to the present application, in step (3), through the second ultrasonic treatment, on the one hand, the alkanolamine can react with the graphene oxide to form alkanolamine-modified graphene oxide, and on the other hand, the uniform loading of the graphene-carbon mixture on the activated carbon can be achieved. The activated carbon is as described in the first aspect of the present application.

[0065] In some embodiments, the dosage of the activated carbon relative to 1 L of the ene-carbon dispersion may be 0.1 - 0.3 kg, such as 0.12 kg, 0.14 kg, 0.15 kg, 0.2 kg, 0.22 kg, 0.23 kg, 0.25 kg, 0.28 kg, etc.

[0066] In some embodiments, the mass ratio of the activated carbon to the ene-carbon mixture (i.e., the mixture of GO and CNTs) in the ene-carbon dispersion may be 100∶(0.2 - 2), preferably 100∶(0.3 - 1).

[0067] In some embodiments, the temperature of the second ultrasonic treatment is 70 - 90 °C, such as 80 °C, 90 °C, etc.; the time of the second ultrasonic treatment is 2 - 6 h, such as 3 h, 4 h, 5 h, 6 h, etc. High-temperature ultrasonic treatment can not only modify GO with alkanolamine, but also promote the good dispersion and attachment of the carbon materials on the inner surface of the pores of the activated carbon, thus improving its adsorption capacity. In addition, the frequency of the second ultrasonic treatment may be 30 - 50 kHz, such as 40 kHz. The reaction system of this ultrasonic treatment can be carried out in a closed or semi-closed space, so as to reduce the solvent volatilization and achieve high-temperature reflux to improve the modification effect.

[0068] In step (3), the alkanolamine may be at least one of monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA), preferably diethanolamine.

[0069] In some embodiments, the dosage of the alkanolamine relative to 1 L of the ene-carbon dispersion is 60 - 110 mL, such as 60 mL, 75 mL, 80 mL, 85 mL, 90 mL, 100 mL, 105 mL, 108 mL, etc.

[0070] According to the present application, through the post-treatment process of step (4), a high-purity solid SO3 adsorbent can be obtained.

[0071] In some embodiments, the method of solid-liquid separation includes screen filtration, and the solvent used for washing is water. Unreacted raw materials (such as the activator and alkanolamine) can be removed by washing. The method of washing may include, for example: washing the solid product with water until the pH of the obtained washing liquid is 8 - 10.

[0072] In step (4), the drying may be, for example, high-temperature drying in an oven, spray drying, freeze drying, etc., preferably oven drying.

[0073] In some embodiments, the drying temperature is 100 - 300 °C, such as 150 °C, 180 °C, 200 °C, 250 °C, etc., and the drying time may be 2 - 12 h, such as 4 h, 5 h, 6 h, 8 h, 10 h, etc.

[0074] The third aspect of the present application provides the use of the SO3 adsorbent described in the first aspect of the present application in removing SO3 from flue gas.

[0075] In some embodiments, it should include: introducing the flue gas to be treated into a fixed-bed device filled with the SO3 adsorbent so that the flue gas to be treated contacts the SO3 adsorbent to obtain desulfurized flue gas. Loading the SO3 adsorbent to form a fixed bed can realize the industrial treatment of flue gas, and the treatment process is simple.

[0076] According to the present application, the flue gas to be treated can be flue gas with a low concentration of SO3 (for example, the SO3 concentration is not higher than 50 mg / m 3 ), or it can also be flue gas with a high concentration of SO3. Especially when continuously treating flue gas with a high concentration of SO3, this adsorbent can maintain a high desulfurization efficiency for a long time. As some examples, the SO3 concentration in the flue gas to be treated is not lower than 100 mg / m 3 , and further can be 100 - 1000 mg / m 3 , such as 500 mg / m 3 , 550 mg / m 3 , 600 mg / m 3 , 800 mg / m 3 , etc.

[0077] As some examples, the flue gas with a high concentration of SO3 can be the flue gas at the SCR outlet during the combustion of high-sulfur coal.

[0078] In some embodiments, relative to 1 kg of the SO3 adsorbent, the dosage of the flue gas to be treated is 100 - 600 m 3 , the temperature of the flue gas to be treated is 60 - 200 °C, such as 70 °C, 80 °C, 100 °C, 150 °C, 170 °C, etc. In addition, the flow rate of the flue gas can be 1 - 5 m 3 / min, such as 1 m 3 / min, 2 m 3 / min, 3 m 3 / min, etc.

[0079] The following describes the embodiments of the present application. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application.

[0080] In the following examples and comparative examples,

[0081] The carbon nanotubes were purchased from Jiangsu Tiannai Technology Co., Ltd., and the grade was FT-2000.

[0082] The activated carbon is columnar coal-based activated carbon, purchased from Ningxia Tingyuan Fruit Wood Energy Technology Co., Ltd. (iodine value ≥ 1000 mg / g, specific surface area is 1000 m 2 / g, diameter is 3 mm).

[0083] Preparation Example 1

[0084] This preparation example is used to illustrate the preparation method of graphene oxide adopted in the following examples and comparative examples.

[0085] Graphene oxide was prepared by the Hummers method: 460 mL of concentrated sulfuric acid (H2SO4, concentration 98 wt%) was added to a beaker and stirred in an ice bath. After the temperature cooled to 0 °C, 20 g of graphite and 10 g of sodium nitrate (NaNO3) were slowly added to the concentrated sulfuric acid and stirred vigorously for 50 min to mix evenly; 60 g of potassium permanganate (KMnO4) was added in batches (5 g every 10 min). After the addition of KMnO4 was completed, the reaction was transferred to a water bath, and the reaction was controlled at 32 - 37 °C and stirred for another 30 min; then 1000 mL of water was added, the temperature was raised to 98 °C, and stirring was continued at this temperature for 15 min. Immediately afterwards, warm water was slowly added to dilute the reaction solution to 3000 mL, and then 370 mL of hydrogen peroxide (H2O2, 5 wt%) was added to reduce the excess KMnO4 in the solution. After filtration, the obtained precipitate was washed with dilute hydrochloric acid and water to obtain graphite oxide. Then, the graphite oxide was added to water, the solid content was controlled at 1 g / L, and ultrasonic treatment was carried out for 60 min to obtain a dispersion of graphene oxide. After freeze-drying, graphene oxide was obtained. By XPS testing, the oxygen content of graphene oxide was 40%.

[0086] Example 1

[0087] Graphene oxide and carbon nanotubes were mixed at a mass ratio of 2:1, diluted with water, and dispersed at high speed with a high-pressure homogenizer at room temperature. The operating pressure was controlled at 100 MPa, and the number of homogenization times was 3 times to obtain a 2 mg / mL graphene-carbon dispersion;

[0088] 6.5 L of the graphene-carbon dispersion was placed in a tank-type ultrasonic machine, 15.5 g of potassium hydroxide was added, and ultrasonic treatment was carried out at 25 °C and 40 kHz for 30 min to activate GO and CNTs to obtain a reaction solution; 500 mL of MEA and 1.5 kg of activated carbon were added to the reaction solution, the temperature was raised to 80 °C, and ultrasonic reaction was continued at 40 kHz for 3 h to form MEA-modified GO (GO-MEA), obtaining a mixed solution containing graphene-carbon (GO-MEA + CNTs)-modified activated carbon; the mixed solution was successively filtered through a sieve and washed with water. The obtained crude product was placed in an oven and dried at 180 °C for 6 h to obtain an SO3 adsorbent, denoted as A-1.

[0089] Example 2

[0090] Graphene oxide and carbon nanotubes were mixed at a mass ratio of 2:1, diluted with water, and dispersed at high speed at room temperature using a high-pressure homogenizer. The operating pressure was controlled at 100 MPa and the number of homogenization times was 3 times to obtain a 2 mg / mL carbon-ene dispersion;

[0091] 7 L of the carbon-ene dispersion was placed in a tank-type ultrasonic machine, 20 g of potassium hydroxide was added, and ultrasonic treatment was carried out at 25 °C and 40 kHz for 60 min to activate GO and CNTs to obtain a reaction solution; 600 mL of DEA and 2 kg of activated carbon were added to the reaction solution, the temperature was raised to 80 °C, and ultrasonic reaction was carried out at this temperature at 40 kHz for 3 h to form DEA-modified GO (GO-DEA), obtaining a mixed solution containing carbon-ene (GO-DEA+CNTs)-modified activated carbon; the mixed solution was successively filtered through a sieve and washed with water, and the obtained crude product was placed in an oven and dried at 270 °C for 6 h to obtain an SO3 adsorbent, denoted as A-2.

[0092] Example 3

[0093] Graphene oxide and carbon nanotubes were mixed at a mass ratio of 2:1, diluted with water, and dispersed at high speed at room temperature using a high-pressure homogenizer. The operating pressure was controlled at 100 MPa and the number of homogenization times was 3 times to obtain a 1 mg / mL carbon-ene dispersion;

[0094] 6.5 L of the carbon-ene dispersion was placed in a tank-type ultrasonic machine, 18 g of potassium hydroxide was added, and ultrasonic treatment was carried out at 25 °C and 40 kHz for 40 min to activate GO and CNTs to obtain a reaction solution; 700 mL of TEA and 1.5 kg of activated carbon were added to the reaction solution, the temperature was raised to 85 °C, and ultrasonic reaction was carried out at this temperature at 40 kHz for 5 h to form TEA-modified GO (GO-TEA), obtaining a mixed solution containing carbon-ene (GO-DEA+CNTs)-modified activated carbon; the mixed solution was successively filtered through a sieve and washed with water, and the obtained crude product was placed in an oven and dried at 200 °C for 8 h to obtain an SO3 adsorbent, denoted as A-3.

[0095] Examples 4 to 6

[0096] The SO3 adsorbent was prepared according to the method of Example 1, except that when preparing the carbon-ene dispersion, the mass ratio of GO and CNTs was adjusted to 1.5:1, 3:1 and 1:1, and the prepared SO3 adsorbents were denoted as A-4, A-5 and A-6 respectively.

[0097] Example 7

[0098] The SO3 adsorbent was prepared according to the method of Example 1, except that the amount of activated carbon used was adjusted to 0.8 kg, and the prepared adsorbent was denoted as A-7.

[0099] Comparative Example 1

[0100] Using activated carbon as a comparative sample, this adsorbent was designated as DA-1.

[0101] Comparative Example 2

[0102] The SO3 adsorbent was prepared according to the method of Example 1, except that MEA was not added. The specific operation is as follows:

[0103] Take 6.5 L of graphene-carbon dispersion and place it in a tank-type ultrasonic machine. Add 15.5 g of potassium hydroxide and ultrasonically treat it at 25 °C and 40 kHz for 30 min to activate GO and CNTs, obtaining a reaction solution; add 1.5 kg of activated carbon to the reaction solution, heat it to 80 °C, and continue to ultrasonically treat it at 40 kHz for 3 h at this temperature to obtain a mixed solution containing graphene-carbon (GO+CNTs) modified activated carbon; filter the mixed solution through a sieve and wash it with water successively. Place the obtained crude product in an oven and dry it at 180 °C for 6 h to obtain the SO3 adsorbent, designated as DA-2.

[0104] Comparative Example 3

[0105] The SO3 adsorbent was prepared according to the method of Example 1, except that carbon nanotubes were not added. The specific operation is as follows:

[0106] Dilute GO with water and disperse it at high speed at room temperature using a high-pressure homogenizer, controlling the operating pressure at 100 MPa and the number of homogenization times at 3 times to obtain a 2 mg / mL GO dispersion;

[0107] Take 6.5 L of GO dispersion and place it in a tank-type ultrasonic machine. Add 15.5 g of potassium hydroxide and ultrasonically treat it at 25 °C and 40 kHz for 30 min to activate GO, obtaining a reaction solution; add 500 mL of MEA (510 g, 8.3 mol) and 1.5 kg of activated carbon to the reaction solution, heat it to 80 °C, and continue to ultrasonically react at 40 kHz for 3 h at this temperature to form GO-MEA, obtaining a mixed solution containing GO-MEA modified activated carbon; filter the mixed solution through a sieve and wash it with water successively. Place the obtained crude product in an oven and dry it at 180 °C for 6 h to obtain the SO3 adsorbent, designated as DA-3.

[0108] In the above examples and comparative examples, the main raw materials and their dosages are shown in Table 1.

[0109] Table 1

[0110]

[0111] Note: The loading amount in Examples 1-7 and Comparative Example 2 refers to the total amount of GO and CNTs as a mass percentage of the amount of activated carbon used; Comparative Example 3 refers to the amount of GO-MEA as a mass percentage of the amount of activated carbon used.

[0112] Test Example

[0113] The following test examples are used to illustrate the treatment effects of adsorbents A-1 to A-7 and DA-1 to DA-3 in the above examples and comparative examples on high-concentration flue gas. Among them, the flue gas at the SCR outlet when a certain power plant burns high-sulfur coal is used as the flue gas to be treated. After being cooled by a scrubber, the main components of the flue gas are shown in Table 2:

[0114] Table 2

[0115] Project <![CDATA[Concentration (mg / m 3 )]]> <![CDATA[SO3]]> 537.665 <![CDATA[SO2]]> 42.734 <![CDATA[N2]]> 857661.7 <![CDATA[O2]]> 113511.8 Water vapor 32367.433

[0116] Test method: Take 1 kg of adsorbent and load it into the desulfurization tank equipment to form a fixed bed. Pass the flue gas to be treated at 80 °C from the bottom of the equipment, control the flue gas flow rate to be 2 m 3 / min, and the flue gas passing time is 240 min. During this period, the flue gas at the outlet of the collection device is collected through a gas collection bag at regular intervals, and a SO3 bench detector is used to test the SO3 concentration in the flue gas at the outlet (also known as the SO3 breakthrough concentration). The desulfurization efficiency is calculated according to the following formula:

[0117] Desulfurization efficiency = [(C0 - C t ) / C0] × 100%, where

[0118] C0 is the initial concentration of SO3 in the flue gas, with the unit of mg / m 3

[0119] C t is the SO3 breakthrough concentration at a certain time, with the unit of mg / m 3 ,

[0120] The test results are shown in Table 3.

[0121] Table 3

[0122]

[0123] Combined with Table 3, comparing Examples 1-7 with Comparative Examples 1-3, it can be seen that when using the adsorbents A-1 to A-7 prepared in Examples 1-7 to treat high-concentration SO3 flue gas, the initial desulfurization efficiency at 30 min of treatment is above 80%, and after 4 h of desulfurization treatment, the adsorbent can still maintain a desulfurization efficiency of more than 65%; while when using the adsorbents DA-1 to DA-3 in Comparative Examples 1-3 to treat high-concentration flue gas, the initial desulfurization efficiency at 30 min of treatment is relatively low, and after 4 h of flue gas treatment, the desulfurization efficiency drops significantly, indicating that their SO3 adsorption capacity for high-concentration SO3 flue gas is limited.

[0124] As can be seen from Comparative Example 1, using activated carbon as the SO3 adsorbent, its adsorption capacity is limited. During the entire 4-hour adsorption treatment, the desulfurization efficiency for high-concentration flue gas never exceeds 56%. From Comparative Examples 2-3, it can be seen that although the activated carbon is modified with carbon nanotubes and graphene oxide modified with alkanolamine respectively, the initial desulfurization efficiency for flue gas can be improved. However, as time prolongs, the desulfurization efficiency will decrease significantly, and long-term and efficient treatment of SO3 in high-concentration SO3 flue gas cannot be achieved.

[0125] In summary, after the activated carbon is modified with the ene-carbon mixture including graphene oxide modified with alkanolamine and carbon nanotubes in this application, the obtained adsorbent has a high SO3 adsorption efficiency. Moreover, when the adsorbent continuously treats high-concentration SO3 flue gas, it can maintain a high adsorption activity for a long time and has high stability.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A SO3 adsorbent, characterized in that, The SO3 adsorbent includes activated carbon and an olefin-carbon mixture supported thereon. Among them, the olefin-carbon mixture includes graphene oxide modified with alkanolamine and carbon nanotubes; the mass ratio of the activated carbon to the olefin-carbon mixture is 100∶(0.2~2), and in the olefin-carbon mixture, the mass ratio of the graphene oxide modified with alkanolamine to the carbon nanotubes is (1~4)∶1.

2. The SO3 adsorbent according to claim 1, wherein The graphene oxide modified with alkanolamine is at least one of graphene oxide modified with monoethanolamine, graphene oxide modified with diethanolamine, and graphene oxide modified with triethanolamine.

3. The SO3 adsorbent according to claim 2, wherein, The graphene oxide modified with alkanolamine is graphene oxide modified with diethanolamine.

4. The SO3 adsorbent according to claim 1, characterized in that, The iodine value of the activated carbon is not less than 800 mg / g, the specific surface area is 500 - 1500 m 2 / g, and the particle size is 3 - 9 mm.

5. The SO3 adsorbent according to claim 1 or 2, characterized in that, The mass ratio of the activated carbon to the olefin-carbon mixture is 100∶(0.3~1); In the olefin-carbon mixture, the mass ratio of the graphene oxide modified with alkanolamine to the carbon nanotubes is (1.5~3)∶1.

6. A method for preparing the SO3 adsorbent according to any one of claims 1-5, characterized in that, This method includes: (1) Uniformly dispersing graphene oxide and carbon nanotubes in a solvent to obtain an olefin-carbon dispersion; (2) Mixing the olefin-carbon dispersion with an activator and performing a first ultrasonic treatment to activate the graphene oxide and carbon nanotubes to obtain a reaction solution; (3) Mixing the reaction solution, alkanolamine, and activated carbon and performing a second ultrasonic treatment to modify the activated graphene oxide with alkanolamine to form graphene oxide modified with alkanolamine to obtain a mixed solution; (4) Performing solid-liquid separation, washing, and drying on the mixed solution to obtain the SO3 adsorbent.

7. The method according to claim 6, wherein In step (1), the solid content of the olefin-carbon dispersion is 1~5 mg / mL, and the solvent is water.

8. The method according to claim 6, wherein The oxygen content of the graphene oxide is 35~45%.

9. The method according to claim 6, wherein The diameter of the carbon nanotubes is 2 to 4 nm, the length is not less than 500 μm, and the specific surface area is not less than 450 m 2 / g.

10. The method according to any one of claims 6-9, characterized in that, In step (2), the activator is potassium hydroxide, and the dosage of potassium hydroxide is 2~3 g relative to 1 L of the olefin-carbon dispersion.

11. The method according to any one of claims 6-9, characterized in that, In step (2), the temperature of the first ultrasonic treatment is 20~40 °C, and the treatment time is 10~60 min.

12. The method according to any one of claims 6-9, characterized in that In step (3), the alkanolamine is at least one of monoethanolamine, diethanolamine, and triethanolamine.

13. The method according to claim 12, wherein The alkanolamine is diethanolamine.

14. The method according to any one of claims 6-9, characterized in that, In step (3), the dosage of the activated carbon is 0.1~0.3 kg relative to 1 L of the olefin-carbon dispersion, and the dosage of the alkanolamine is 60~110 mL.

15. The method according to any one of claims 6-9, characterized in that, In step (3), the temperature of the second ultrasonic treatment is 70~90 °C, and the treatment time is 2~6 h.

16. The method according to any one of claims 6-9, characterized in that, In step (4), the method of solid-liquid separation includes screen filtration, and the solvent used for washing is water.

17. The method according to any one of claims 6-9, characterized in that, In step (4), the drying temperature is 100~300 °C, and the drying time is 2~12 h.

18. Application of the SO3 adsorbent according to any one of claims 1-5 in removing SO3 from flue gas.

19. The application according to claim 18, wherein This application includes: Passing the flue gas to be treated into a fixed-bed device filled with the SO3 adsorbent so that the flue gas to be treated contacts the SO3 adsorbent to obtain desulfurized flue gas.

20. The application according to claim 19, wherein The concentration of the SO3 adsorbent in the flue gas to be treated is not less than 100 mg / m 3 .

21. The application according to claim 19, wherein Relative to 1 kg of the SO3 adsorbent, the dosage of the flue gas to be treated is 100~600 m³, and the temperature of the flue gas to be treated is 60~200 °C.

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