Carbon dioxide absorption liquid, application thereof and method for treating carbon dioxide

Abstract

The invention belongs to the field of carbon dioxide absorption and provides carbon dioxide absorption liquid and application thereof and a method for treating carbon dioxide. The carbon dioxide absorption liquid comprises water, a thermodynamic accelerant and a dynamic accelerant, the dynamic accelerant comprises amino modified graphene oxide, and the amino modified graphene oxide is tertiary amino modified graphene oxide. The reaction between the carbon dioxide absorption liquid and carbon dioxide has a high hydrate generation rate, and the separation efficiency of carbon dioxide can be improved.

Description

Technical Field

[0001] The present application belongs to the field of gas adsorption, and specifically provides a carbon dioxide absorbing liquid and its application and a method for treating carbon dioxide. Background Art

[0002] With the progress of industrialization, carbon dioxide (CO 2 ) Climate change and environmental problems exacerbated by excessive emissions have attracted widespread attention. As one of the greenhouse gases, the concentration of carbon dioxide in the atmosphere has increased from 278ppm at the beginning of the industrial revolution to more than 400ppm today. In order to control the temperature rise below 2°C, it is crucial to achieve net zero carbon dioxide emissions as soon as possible. At present, a variety of methods have been developed to capture carbon dioxide from industrial flue gas, mainly including: chemical absorption, physical adsorption, membrane separation, low-temperature condensation, etc. Although these methods can alleviate the problem of carbon dioxide emissions to a certain extent, there are still some serious shortcomings. For example, the amine liquid chemical absorption method, which is the most mature and widely used in industry, has problems such as high solvent circulation energy consumption, high cost, and equipment corrosion.

[0003] In recent years, gas hydrate technology has become a research hotspot due to its low energy consumption, low cost, simple operation process and environmental friendliness. 2 The ice-like crystalline substance formed by gas molecules and water under high pressure and low temperature conditions can effectively separate CO from flue gas by utilizing the large difference in the phase equilibrium formed by hydrates. 2 For flue gas containing multiple components, CO 2 It can be captured by the water cavity in the form of solid hydrates, while the remaining components that are difficult to hydrate are released, and CO can be transported to the atmosphere by changing the surrounding environment. 2 is released again. Therefore, CO 2 The hydration technology is an effective combination of capture, transportation and storage technologies. 2 It saves a lot of steps and money in disposal.

[0004] In order to improve the hydration adsorption effect, the research and development of gas promoters is particularly important for improving the hydrate method for gas separation technology. Promoters are divided into thermodynamic promoters and kinetic promoters. Common kinetic promoters include surfactants, such as sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS), but most of these kinetic promoters have problems such as environmental pollution; thermodynamic promoters mainly include tetrahydrofuran, tetrabutylammonium fluoride, etc. These promoters can effectively move the hydration equilibrium conditions to milder conditions. However, the separation of carbon dioxide based on hydrates is still limited by the slow hydrate formation rate and low carbon dioxide separation efficiency, which seriously hinders the development of this type of carbon dioxide separation technology. Summary of the invention

[0005] In view of the above problems existing in the prior art, the purpose of the present application is to provide a carbon dioxide absorbing liquid and its application and a method for treating carbon dioxide. The carbon dioxide absorbing liquid reacts with carbon dioxide to form a high hydrate and can improve the separation efficiency of carbon dioxide.

[0006] In a first aspect, the present application provides a carbon dioxide absorption liquid, which comprises water, a thermodynamic promoter and a kinetic promoter, wherein the kinetic promoter comprises amine-modified graphene oxide, and the amine-modified graphene oxide is tertiary amine-modified graphene oxide.

[0007] In the carbon dioxide absorption liquid of the present application, the use of a thermodynamic promoter can promote the hydration phase transition equilibrium to move to high temperature and low pressure. The use of amine-modified graphene oxide as a kinetic promoter can further improve the utilization rate of the thermodynamic promoter and form more carbon dioxide hydrates more quickly. The amine-modified graphene oxide provides tertiary amine groups, which will convert more CO2 in the gas phase into 2 Introducing water phase (R 3 N+H 2 O+CO 2 =R 3 NH + +HCO 3- , R represents the graphene oxide part), increasing the liquid phase CO 2 The capacity can better promote the occurrence of hydration reaction. At the same time, the amine-modified graphene oxide does not affect the properties of the graphene oxide part as a hydration kinetics promoter: because the graphene oxide structure is hydrophobic in the middle and hydrophilic around, the hydrophilic end can connect water molecules and the hydrophobic end can connect gas, playing a mass transfer role, similar to the role of surfactant. In addition, since the carbon dioxide absorption liquid of the present application is 2 The hydration phase change reaction is a physical change, and the introduced amine-modified graphene oxide reacts with CO 2 There is no chemical reaction, so the absorbed CO 2 It decomposes and releases naturally at normal temperature and pressure, greatly saving energy consumption.

[0008] In some embodiments of the present application, the mass content of the amine-modified graphene oxide is 90 to 120 mg / L.

[0009] In some embodiments of the present application, the mass of the thermodynamic promoter is 2 to 10 parts by weight relative to 100 parts by weight of water.

[0010] In some embodiments of the present application, the amine-modified graphene oxide is obtained by modifying graphene oxide with an amino modifier, and the amino modifier is selected from at least one of an alcohol amine and a tertiary amino silane coupling agent, wherein the alcohol amine is diethanolamine and / or triethanolamine.

[0011] In some embodiments of the present application, the tertiary amino silane coupling agent is [3-(diethylamino)propyl]trimethoxysilane.

[0012] In some embodiments of the present application, the amine-modified graphene oxide is prepared by a method comprising the following steps: adding potassium hydroxide to a graphene oxide dispersion to activate the graphene oxide, then adding the alcoholamine, heating to reflux and reacting for 2 to 5 hours, and filtering, washing and drying the obtained solid-liquid products.

[0013] Furthermore, the graphene oxide concentration in the graphene oxide dispersion is 1-3 mg / mL, the mass ratio of potassium hydroxide to graphene oxide is 1:(0.6-1.2), and the volume ratio of the alcoholamine to the graphene oxide dispersion is 1:(12-15).

[0014] In some embodiments of the present application, the amine-modified graphene oxide is prepared by a method comprising the following steps: mixing a graphene oxide dispersion, the tertiary amino silane coupling agent and an alcohol, stirring at 20 to 40° C. for 20 to 50 minutes, heating to reflux for 5 to 7 hours, and filtering, washing and drying the obtained solid-liquid products.

[0015] Furthermore, the graphene oxide concentration in the graphene oxide dispersion is 1-3 mg / mL, the volume ratio of the graphene oxide dispersion to the alcohol is 1:(8-12), and the mass ratio of the tertiary amino silane coupling agent to the graphene oxide is (10-20):1.

[0016] In some embodiments of the present application, the thermodynamic promoter is selected from one or more of tetrabutylammonium fluoride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium nitrate, cyclopentane, tetrahydrofuran, 1,3-dioxolane, 1,3-dioxane, methylcyclopentane and neohexane.

[0017] Furthermore, the thermodynamic promoter is selected from tetrabutylammonium bromide (TBAB) and tetrahydrofuran (THF). Compared with other thermodynamic promoters, TBAB and THF produce a synergistic effect in promoting hydration phase transition. THF enters the cage structure of TBAB hydrate to displace TBAB ions, and the displaced TBAB ions can re-combine with water molecules to generate CO again. 2 Hydrates, which can further increase the CO 2 Absorption efficiency.

[0018] In some embodiments of the present application, the kinetic promoter also includes amino acids. When the hydration adsorption reaction occurs, a large amount of solid hydrates will be generated, which will cover the gas-liquid surface in large quantities, resulting in poor contact, and the amino acids can effectively disperse the hydrates on the wall of the reactor, thereby promoting full contact of the gas-liquid interface and ensuring full utilization of the amino-modified graphene oxide.

[0019] Furthermore, in the carbon dioxide absorption liquid, the mass content of amino acids is 1 to 10 mg / L.

[0020] In a second aspect, the present application provides the use of the carbon dioxide absorption liquid described in the first aspect of the present application in treating waste gas from a tobacco factory or exhaust gas from a car.

[0021] In a third aspect, the present application provides a method for treating carbon dioxide, the method comprising: subjecting a mixed gas containing carbon dioxide to a hydration reaction with the carbon dioxide absorption liquid described in the first aspect of the present application to form carbon dioxide hydrate.

[0022] In some embodiments of the present application, the volume concentration of carbon dioxide in the mixed gas is ≥10%.

[0023] In some embodiments of the present application, the temperature of the hydration reaction is 0-6°C, and the intake pressure is 1.3-2.5 MPa.

[0024] In some embodiments of the present application, the method further comprises: desorbing the carbon dioxide hydrate at a desorption temperature of 15 to 30° C. In particular, the formed hydrate can effectively release carbon dioxide at room temperature, greatly saving consumption.

[0025] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. DETAILED DESCRIPTION

[0026] The following describes the implementation of the present application in detail. The implementation described below is exemplary and is only used to explain the present application, and cannot be understood as limiting the present application.

[0027] The "range" disclosed in the present application is defined in the form of a lower limit and / or an upper limit, and a given range is defined by selecting a lower limit and / or an upper limit. The range defined in this way can be inclusive or exclusive of end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form an unclearly recorded range, and any lower limit can be combined with other lower limits to form an unclearly recorded range, and any upper limit can be combined with any other upper limit to form an unclearly recorded range. In addition, each separately disclosed point or single value itself can be combined with any other point or single value as a lower limit or upper limit or with other lower limits or upper limits to form an unclearly recorded range.

[0028] If not otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0029] The formation of hydrates requires the presence of guest gas molecules, such as carbon dioxide, nitrogen, methane and other gases. Therefore, one of the key issues in the formation of carbon dioxide hydrates is how to introduce a large amount of carbon dioxide into the liquid phase to increase the effective contact between the gas and the liquid. In traditional methods, the entry of carbon dioxide into the liquid phase mainly relies on the driving force of the gas phase pressure and the role of surfactants in reducing the surface tension of the liquid phase. However, the gas phase pressure is costly for industrialization, and the surfactants are polluting and cannot be recycled. Therefore, it is very necessary to allow more carbon dioxide to enter the liquid phase from the gas phase. At the same time, the sealed carbon dioxide needs to be released under mild conditions so that the hydration promoter can be recycled multiple times to reduce costs.

[0030] To this end, a first aspect of the present application provides a carbon dioxide adsorption liquid, which contains water, a thermodynamic promoter and a kinetic promoter, wherein the kinetic promoter includes amine-modified graphene oxide.

[0031] In the present application, the amine-modified graphene oxide is a tertiary amine-modified graphene oxide. The tertiary amine group will convert more CO 2 Introducing water phase to increase liquid phase CO 2 capacity to better promote the hydration reaction, increase the speed of hydration phase change, and make the absorbed CO 2 It is naturally decomposed and released at normal temperature and pressure. In particular, this method of promoting absorption and desorption is also different from the traditional method of capturing carbon dioxide with amine liquid. The amine liquid method of absorbing carbon dioxide uses a specific chemical reaction between amine groups and carbon dioxide (R-NH 2 +CO 2 =R-NH 2+ —COO -, where R represents graphene oxide) The desorption of carbon dioxide in such reactions requires a temperature of at least 65°C to release the carbon dioxide again.

[0032] In some embodiments, the mass content of the amine-modified graphene oxide in the carbon dioxide adsorption liquid is 90-120 mg / L, such as 90 mg / L, 95 mg / L, 97 mg / L, 98 mg / L, 100 mg / L, 105 mg / L, 110 mg / L, etc. In this case, the amine-modified graphene oxide can further reduce the possibility of difficulty in hydration generation due to its large-scale capture of gas while playing a role in promoting hydration.

[0033] In the present application, the amine-modified graphene oxide can be prepared by modifying graphene oxide with an amino modifier, and the tertiary amine group provided by the amino modifier can be introduced into the graphene oxide group by a grafting reaction between the oxygen-containing functional group (e.g., epoxy group) on the graphene oxide and the amino modifier. As some examples, the graphene oxide (GO) can be prepared by the Hummers method or the improved Hummers method.

[0034] In some embodiments, the amino modifier may be selected from at least one of an alcohol amine and a tertiary amino silane coupling agent.

[0035] In the present application, the alcoholamine is diethanolamine (DEA) and / or triethanolamine (TEA).

[0036] Preferably, the tertiary amino silane coupling agent is [3-(diethylamino)propyl]trimethoxysilane.

[0037] As a specific implementation manner, the amine-modified graphene oxide is alcoholamine-modified graphene oxide, and the preparation method of alcoholamine-modified graphene oxide includes:

[0038] (1) adding potassium hydroxide to the graphene oxide dispersion to activate the graphene oxide;

[0039] (2) adding the alcohol amine, raising the temperature to reflux and reacting for 2 to 5 hours, and filtering, washing and drying the obtained solid and liquid products.

[0040] Furthermore, the concentration of the graphene oxide dispersion may be 1-3 mg / mL, the mass ratio of potassium hydroxide to graphene oxide may be 1:(0.6-1.2), and the volume ratio of alcoholamine to the graphene oxide dispersion may be 1:(12-15).

[0041] As another specific embodiment, the amine-modified graphene oxide is a tertiary amine silane coupling agent modified graphene oxide, and its preparation method includes: mixing a graphene oxide dispersion, a tertiary amine silane coupling agent and an alcohol, stirring at 20 to 40° C. for 20 to 50 minutes, heating to reflux reaction for 5 to 7 hours, and filtering, washing and drying the obtained solid-liquid products.

[0042] Furthermore, the graphene oxide concentration in the graphene oxide dispersion can be 1-3 mg / mL, the volume ratio of the graphene oxide dispersion to alcohol (such as ethanol) can be 1:(8-12), and the mass ratio of the tertiary amino silane coupling agent to graphene oxide is (10-20):1.

[0043] In the present application, the thermodynamic promoter is intended to improve the conditions of the hydration phase transition, which will move the phase transition in the direction of high temperature and low pressure. The present application does not particularly limit the type of the thermodynamic promoter, and can refer to the existing promoter selection. As some examples, the thermodynamic promoter can be selected from tetrabutylammonium fluoride, tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride, tetrabutylammonium nitrate, cyclopentane, tetrahydrofuran (THF), 1,3 dioxolane, 1,3-dioxane, methylcyclopentane and neohexane, etc. One or more.

[0044] Preferably, the thermodynamic promoter is selected from tetrabutylammonium bromide and tetrahydrofuran.

[0045] More preferably, the molar ratio of tetrabutylammonium bromide to water is (0.1-0.5):100, for example 0.2:100, 0.25:100, 0.29:100, 0.3:100, 0.4:100, etc.; the volume ratio of tetrahydrofuran to water is (1-5):100, for example 2:100, 2.5:100, 3:100, 3.2:100, 4:100, 5:100, etc.

[0046] In some embodiments, the kinetic promoter also includes amino acids. Generally, the hydration adsorption reaction is carried out in a reactor, and a large amount of solid hydrates generated by the reaction will cover the gas-liquid surface, resulting in poor contact, while amino acids can effectively disperse the hydrates on the reactor wall, promote full contact of the gas-liquid interface, and ensure full utilization of the amino-modified graphene oxide.

[0047] As some examples, the amino acid may be selected from one or more of L-leucine, methionine, tryptophan, isoleucine, norvaline and aminoheptanoic acid.

[0048] In some embodiments, the mass content of amino acids in the carbon dioxide absorption liquid can be 1 to 10 mg / L, for example, 1 mg / L, 2 mg / L, 5 mg / L, 8 mg / L, 10 mg / L, etc.

[0049] Preferably, the kinetic promoter is the amine-modified graphene oxide and the amino acid, and the mass ratio of the two is (8-12):1, for example, 10:1.

[0050] Optionally, the kinetic promoter further comprises graphene oxide. In the carbon dioxide absorption liquid, the mass content of graphene oxide can be 0-10 mg / L, for example, 2 mg / L, 3 mg / L, 4 mg / L, 5 mg / L, 8 mg / L, 10 mg / L, etc.

[0051] In some embodiments, in the carbon dioxide absorption liquid, the mass ratio of the thermodynamic promoter to the kinetic promoter may be (500-1000):1, for example, 500:1, 550:1, 600:1, 700:1, 720:1, 750:1, 800:1, etc.

[0052] The present application has no particular restrictions on the preparation method of the carbon dioxide adsorption liquid, as long as the various promoters can be evenly distributed in water. As some examples, the carbon dioxide adsorption liquid can be prepared by mixing the thermodynamic promoter, the kinetic promoter and water and then performing ultrasonic dispersion. The ultrasonic dispersion time can be, for example, 10 to 50 minutes, and the ultrasonic dispersion can be performed at room temperature or at a heated temperature.

[0053] As mentioned above, the carbon dioxide adsorption liquid of the present application increases the CO 2 The amount of gas entering the liquid phase increases the gas-liquid contact. In the compound promoter composed of thermodynamic promoter and kinetic promoter, the tertiary amine structure interacts with CO 2 The specific reaction improves the problem of low generation rate and poor generation efficiency of carbon dioxide hydrate, which can significantly shorten the generation time of carbon dioxide hydration and significantly increase the hydration generation amount, which is conducive to the industrial capture of carbon dioxide absorption liquid and can achieve CO2 hydrate at room temperature. 2 The desorption of carbon dioxide absorption liquid can be realized, thereby reducing energy consumption and disposal costs.

[0054] To this end, the second aspect of the present application provides the use of the carbon dioxide absorption liquid in treating tobacco factory waste gas or automobile exhaust gas.

[0055] The third aspect of the present application provides a method for treating carbon dioxide, which comprises: subjecting a mixed gas of carbon dioxide to a hydration reaction with the carbon dioxide absorption liquid described in the first aspect of the present application to form carbon dioxide hydrate.

[0056] The method for treating carbon dioxide in this application is not limited by the gas phase pressure and can effectively reduce the pressure limit of the carbon dioxide hydration reaction. The operating pressure required for the general hydration reaction must be greater than 2.5MPa to have a higher CO 2 The separation efficiency can be improved, and the use of the carbon dioxide absorbing liquid can effectively reduce the operating pressure to below 2.5 MPa.

[0057] In some embodiments, the volume concentration of carbon dioxide in the mixed gas is ≥10%, for example, 15% to 20%.

[0058] Optionally, the mixed gas further comprises nitrogen, and the volume concentration of the nitrogen may be 80% to 85%.

[0059] As some examples, the mixed gas is tobacco factory exhaust gas.

[0060] In some embodiments, the temperature of the hydration reaction is 0-6°C, and the inlet pressure is 1.3-2.5 MPa, for example 2 MPa. In particular, the operating pressure required for the general hydration reaction must be greater than 2.5 MPa to have a higher CO 2 The separation efficiency can be improved, and the use of the carbon dioxide absorbing liquid can effectively reduce the operating pressure to below 2.5 MPa.

[0061] In order to achieve the recycling of carbon dioxide, according to some embodiments, the method further comprises: desorbing carbon dioxide hydrate, preferably at a temperature of 10 to 30°C.

[0062] The following describes 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 limiting the present application.

[0063] Preparation Examples 1 to 4 are used to illustrate the preparation methods of graphene oxide and amine-modified graphene oxide used in the examples and comparative examples.

[0064] Preparation Example 1

[0065] Graphene oxide was prepared by a modified Hummers method.

[0066] 3.0 g of graphite powder and 1.5 g of NaNO 3 Mix well in a beaker, place the beaker in an ice bath, then add 69 mL of concentrated sulfuric acid (98 wt%) and stir. After the mixture is cooled to 0°C, slowly add 9.0 g of KMnO in 6 batches. 4The reaction was stirred under magnetic stirring at a temperature below 20°C for 2 hours, and then the temperature of the reaction system was raised to 35°C and kept at this temperature for 3 hours. The temperature was then raised to 98°C and kept at this temperature for 1.5 hours. The reaction product was cooled, and when the temperature dropped to room temperature, the solution was poured into a 400 mL ice water and 3 mL 30 wt% H 2 O 2 After stirring evenly, filter with a 300 μm standard sieve, and then centrifuge (10000 r / min) to separate and retain the solids.

[0067] The solid was washed with 200 mL of distilled water, 200 mL of hydrochloric acid (mass concentration 10%) and 200 mL of ethanol, respectively, twice each time. The solid was separated by centrifugation after each washing. After the last centrifugation to separate the solid, the product was vacuum dried at room temperature for 12 h. The brown-black block solid finally obtained was the prepared graphene oxide (GO).

[0068] Preparation Example 2

[0069] Graphene oxide was diluted with water to a graphene oxide dispersion with a concentration of 2 mg / mL. 65 mL of graphene oxide dispersion was placed in a three-necked flask, 0.16 g of potassium hydroxide was added, and ultrasonic treatment was performed for 30 minutes. Then 5 mL of diethanolamine (DEA) was added to the above solution, and refluxed for 3 hours in a water bath at 80°C. After the reaction, a black solution was obtained, and the reaction product was dialyzed to neutrality and freeze-dried to obtain diethanolamine-modified graphene oxide, which was recorded as DEA-GO.

[0070] Preparation Example 3

[0071] Amine-modified graphene oxide was prepared according to the method of Preparation Example 2, except that diethanolamine was replaced by triethanolamine (TEA) to obtain triethanolamine-modified graphene oxide, which was recorded as TEA-GO.

[0072] Preparation Example 4

[0073] Graphene oxide was diluted with water to a graphene oxide dispersion with a concentration of 2 mg / mL. 15 mL of graphene oxide aqueous dispersion and 0.5 g of [3-(diethylamino)propyl]trimethoxysilane were slowly added to a three-necked flask containing 150 mL of ethanol, stirred at room temperature for 40 minutes, then heated to reflux and reacted for 6 hours. The product obtained by the reaction was separated from the solid and liquid, washed with ethanol and deionized water, and freeze-dried to obtain [3-(diethylamino)propyl]trimethoxysilane-modified graphene oxide, denoted as NEt 2 -GO.

[0074] The following examples are used to illustrate the carbon dioxide absorbing liquid and the carbon dioxide treatment method of the present invention.

[0075] Comparative Example 1

[0076] Tetrabutylammonium bromide (51.6 g, 0.16 mol) was mixed with 25 mL of tetrahydrofuran, 100 mg of L-methionine and water (1 L, 55.6 mol), and then ultrasonically dispersed at room temperature for 30 minutes to obtain a carbon dioxide absorption liquid, which was recorded as D1.

[0077] Comparative Example 2

[0078] Tetrabutylammonium bromide (51.6 g, 0.16 mol) was mixed with 25 mL of tetrahydrofuran, 100 mg of graphene oxide and water (1 L, 55.6 mol), and then ultrasonically dispersed at room temperature for 30 minutes to obtain a carbon dioxide absorption liquid, which was recorded as D2.

[0079] Comparative Example 3

[0080] Tetrabutylammonium bromide (51.6 g, 0.16 mol) was mixed with 25 mL of tetrahydrofuran, sodium dodecyl sulfate (SDS, 3 g) and water (1 L, 55.6 mol), and then ultrasonically dispersed at room temperature for 30 minutes to obtain a carbon dioxide absorption liquid, which was recorded as D3.

[0081] Example 1

[0082] Tetrabutylammonium bromide (51.6 g, 0.16 mol), tetrahydrofuran 25 mL, amine-modified graphene oxide NEt 2 -GO 100 mg and water (1 L, 55.6 mol) were mixed and ultrasonically dispersed at room temperature for 30 minutes to obtain a carbon dioxide absorption liquid, which was recorded as A1.

[0083] Example 2

[0084] Tetrabutylammonium bromide (51.6 g, 0.16 mol), tetrahydrofuran 25 mL, amino-modified graphene oxide TEA-GO 100 mg and water (1 L, 55.6 mol) were mixed and ultrasonically dispersed at room temperature for 30 minutes to obtain a carbon dioxide absorption liquid, which was recorded as A2.

[0085] Example 3

[0086] Tetrabutylammonium bromide (51.6 g, 0.16 mol), tetrahydrofuran 25 mL, amino-modified graphene oxide DEA-GO 105 mg and water (1 L, 55.6 mol) were mixed and ultrasonically dispersed at room temperature for 30 minutes to obtain a carbon dioxide absorption liquid, which was recorded as A3.

[0087] Example 4

[0088] A carbon dioxide absorption liquid was prepared according to the method of Example 1, except that 10 mg of L-methionine was additionally added. The prepared carbon dioxide absorption liquid was recorded as B1.

[0089] Example 5

[0090] A carbon dioxide absorption liquid was prepared according to the method of Example 2, except that 100 mg of TEA-GO was replaced by 97 mg of TEA-GO and 3 mg of L-methionine. The prepared carbon dioxide absorption liquid was recorded as B2.

[0091] Example 6

[0092] A carbon dioxide absorption liquid was prepared according to the method of Example 2, except that 100 mg of TEA-GO was replaced by 97 mg of TEA-GO and 3 mg of graphene oxide. The prepared carbon dioxide absorption liquid was recorded as B3.

[0093] The compositions of the absorption liquids in the above embodiments and comparative examples are specifically shown in Table 1.

[0094] Test Case

[0095] 1. Hydration effect test

[0096] Carbon dioxide adsorption: The temperature of the hydration reactor filled with carbon dioxide absorption liquid was lowered by 6°C, and a mixed gas of carbon dioxide and nitrogen (CO 2 The volume concentration is 15%), the inlet pressure is controlled to be 2 MPa, stirring is turned on, and the stirring speed is 900 rpm; when the pressure decreases slowly, stirring is turned off, and the reaction is stopped after 2 hours.

[0097] Carbon dioxide desorption: After the reaction is completed, the temperature of the hydration reactor is raised to 25°C to start desorption. After 30 minutes of desorption, the gas in the reactor is tested by gas chromatography to calculate the carbon dioxide separation efficiency. The calculation formula for the separation efficiency is:

[0098] in,

[0099] S Fr Indicates CO 2 Separation efficiency;

[0100] CO before the reaction 2 The amount of substance,

[0101] CO detected at the outlet after the reaction 2 The amount of substance;

[0102] The test results are shown in Table 1.

[0103] Table 1

[0104]

[0105] 1: The volume usage of THF is based on the volume usage of water;

[0106] 2: The molar amount of TABA is based on the molar mass of water;

[0107] 3: The mass dosage of SDS is based on the mass of water.

[0108] Combining Table 1, it can be seen that by comparing Examples 1 to 6 with Comparative Examples 1 to 3, compared with the use of commonly used amino acids, GO and SDS, the introduction of amine-modified graphene oxide as a kinetic promoter can improve the CO 2 Hydrate formation rate.

[0109] Comparing Examples 4 to 5 with Examples 1 to 2 and 6, it can be seen that compared with not adding amino acids and only using amino-modified graphene oxide (Examples 1 to 2), or using amino-modified graphene oxide and GO compounded (Example 6) as kinetic promoters, using amino acids and amino-modified graphene together as kinetic promoters (Examples 4 to 5) can significantly improve CO 2 Although GO is slightly stronger than amino acids in terms of kinetic promotion effect (see Comparative Examples 1 and 2), the kinetic promotion effect of amino acids and amine-modified graphene oxide is slightly stronger than the combination of GO and amine-modified graphene oxide, indicating that amine-modified graphene oxide and amino acids have a synergistic promotion effect: amino acids can effectively disperse hydrates on the wall of the reactor, thereby ensuring sufficient contact of the gas-liquid interface and ensuring full utilization of amine-modified graphene oxide.

[0110] 2. Cycle stability test

[0111] According to item 1 (hydration effect test), the adsorption and desorption experiments of carbon dioxide are carried out. This is a cycle, and the adsorption and desorption experiments are repeated. After each cycle test, the CO 2 Separation efficiency, CO per experiment 2 The separation efficiency test results are shown in Table 2.

[0112] Table 2

[0113] Absorption liquid number first 2nd time 3rd 4th 5th 6th D2 62.68％ 61.2％ 60.56％ 58.86％ 58.5％ 58.47％ A1 67.77％ 66.82％ 66.04％ 64.92％ 64.68％ 64.43％ A2 69.64％ 68.75％ 67.48％ 65.43％ 65.26％ 65.18％ B1 71.67％ 69.47％ 68.78％ 66.57％ 66.43％ 66.58％

[0114] Combining Table 1 and Table 2, it can be seen that the CO 2 The separation efficiency only decreased by about 5%, which is comparable to that of the absorption liquid (D2) using GO as a kinetic promoter. On the one hand, it shows that the absorption liquid with tertiary amine-modified graphene oxide as a kinetic promoter can achieve CO 2 Phase change desorption (if the normal temperature phase change desorption is not achieved, the CO2 The separation efficiency will drop significantly after recycling); on the other hand, it also shows that tertiary amine-modified graphene oxide can be recycled and has high cyclic stability.

[0115] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A carbon dioxide absorbing liquid, characterized in that: It comprises water, a thermodynamic promoter and a kinetic promoter, wherein the kinetic promoter comprises amine-modified graphene oxide, and the amine-modified graphene oxide is tertiary amine-modified graphene oxide.

2. The carbon dioxide absorbing liquid according to claim 1, characterized in that The mass content of the amino-modified graphene oxide is 90 to 120 mg / L; Preferably, the mass of the thermodynamic promoter is 2 to 10 parts by weight relative to 100 parts by weight of water.

3. The carbon dioxide absorbing liquid according to claim 1 or 2, characterized in that: The amine-modified graphene oxide is prepared by modifying graphene oxide with an amino modifier, and the amino modifier is selected from at least one of an alcohol amine and a tertiary amino silane coupling agent, wherein the alcohol amine is diethanolamine and / or triethanolamine; Preferably, the tertiary amino silane coupling agent is [3-(diethylamino)propyl]trimethoxysilane.

4. The carbon dioxide absorbing liquid according to claim 3, characterized in that: The amine-modified graphene oxide is prepared by a method comprising the following steps: adding potassium hydroxide to a graphene oxide dispersion to activate the graphene oxide, then adding the alcohol amine, heating to reflux and reacting for 2 to 5 hours, and filtering, washing and drying the obtained solid and liquid products; Preferably, the graphene oxide concentration in the graphene oxide dispersion is 1 to 3 mg / mL, the mass ratio of potassium hydroxide to graphene oxide is 1:(0.6 to 1.2), and the volume ratio of the alcoholamine to the graphene oxide dispersion is 1:(12 to 15); or, The amine-modified graphene oxide is prepared by a method comprising the following steps: mixing a graphene oxide dispersion, a tertiary amino silane coupling agent and an alcohol, stirring at 20 to 40° C. for 20 to 50 minutes, heating to reflux for 5 to 7 hours, and filtering, washing and drying the obtained solid and liquid products; Preferably, the graphene oxide concentration in the graphene oxide dispersion is 1-3 mg / mL, the volume ratio of the graphene oxide dispersion to alcohol is 1:(8-12), and the mass ratio of the tertiary amino silane coupling agent to graphene oxide is (10-20):

1.

5. The carbon dioxide absorbing liquid according to any one of claims 1 to 4, characterized in that: The thermodynamic promoter is selected from one or more of tetrabutylammonium fluoride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium nitrate, cyclopentane, tetrahydrofuran, 1,3-dioxolane, 1,3-dioxane, methylcyclopentane and neohexane; Preferably, the thermodynamic promoter is tetrabutylammonium bromide and tetrahydrofuran; Preferably, the molar ratio of tetrabutylammonium bromide to water is (0.1-0.5):100, and the volume ratio of tetrahydrofuran to water is (1-5):

100.

6. The carbon dioxide absorbing liquid according to any one of claims 1 to 5, characterized in that: The kinetic promoter also includes amino acids; Preferably, the mass content of amino acids in the carbon dioxide absorption liquid is 1 to 10 mg / L; Preferably, in the carbon dioxide adsorption liquid, the total mass content of the kinetic promoter is 100-120 mg / L.

7. Use of the carbon dioxide absorption liquid according to any one of claims 1 to 6 in treating waste gas from tobacco factories or automobile exhaust.

8. A method for treating carbon dioxide, characterized in that: The method comprises: subjecting a mixed gas containing carbon dioxide to a hydration reaction with the carbon dioxide absorbing liquid according to any one of claims 1 to 6 to form carbon dioxide hydrate.

9. The method according to claim 8, characterized in that In the mixed gas, the volume concentration of carbon dioxide is ≥10%; Preferably, the temperature of the hydration reaction is 0-6°C, and the intake pressure is 1.3-2.5 MPa.

10. The method according to claim 8 or 9, characterized in that: Also includes: The carbon dioxide hydrate is desorbed at a desorption temperature of 10 to 30°C.

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