Absorbent and application thereof in carbon dioxide capture

Abstract

The invention discloses an absorbent and application thereof in carbon dioxide capture, and belongs to the technical field of carbon dioxide emission reduction. The absorbent provided by the invention comprises an alcohol ether compound, the chemical formula of the alcohol ether compound is as shown in a formula (I): # imgabs0 # in the formula (I), n is greater than 2; r < 1 > is an alkylene group with 1 to 10 carbon atoms; and R < 2 > and R < 3 > are respectively and independently H or C1-C10 alkyl. The alcohol ether compound has proper polarity, volatility and viscosity by regulating and controlling the ether group, hydroxyl group and alkyl group structures of the alcohol ether compound, and the physical and chemical characteristics of the absorbent can be optimized by taking the alcohol ether compound as a component of the absorbent, so that the absorbent has the advantages of low viscosity, low volatility, low cost and high safety; therefore, the method has a good application effect in carbon dioxide capture.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide emission reduction, and in particular relates to an absorbent and application thereof in carbon dioxide capture. Background Art

[0002] For coal-fired power plants, steel, cement and other low CO 2 To reduce carbon dioxide emissions from flue gas, post-combustion chemical absorption can be used to capture carbon dioxide. The carbon capture process using organic amines as the absorption liquid is currently the most mature and commercially used technology. Among them, ethanolamine (MEA) is the earliest commercially used carbon capture absorbent, which has the advantages of good absorption effect and low cost, but has problems such as high energy consumption, easy degradation, and high corrosiveness. The development of new absorbents with efficient and stable absorption performance and low operating costs plays an important role in the application of carbon capture technology and in helping to achieve the strategic goals of carbon peak and carbon neutrality.

[0003] In recent years, many researchers have proposed various types of new absorbents, including mixed amine absorbents, two-phase absorbents, and low-water absorbents, to reduce the energy consumption and operating costs of carbon capture. Among them, the two-phase absorbent is mainly composed of organic amines, phase separation agents, and water. The phase separation agent is generally a tertiary amine or an organic solvent. The two-phase absorbent has a high absorption rate in CO2 absorption. 2 After that, two immiscible lean liquid phases (CO 2 low content) and rich liquid phase (CO 2 The lean liquid after separation of the two is circulated to the absorption tower to capture CO 2 , and the rich liquid is circulated to the desorption tower for desorption. This process can not only improve the efficiency of the absorption and desorption processes, but also effectively reduce the consumption of sensible heat and latent heat of vaporization in the regeneration process, thereby reducing energy costs. The low-water absorbent is composed of organic amines, non-aqueous solvents and water. The non-aqueous solvent is an organic solvent, which has a lower specific heat capacity than water. Therefore, the low-water absorbent has a lower energy consumption potential than conventional mixed amine absorbents.

[0004] In two-phase absorbents and water-reducing absorbents, organic solvents are important components. The organic solvents published in existing invention patents are mainly n-propanol, n-butanol, cyclopentane, dimethyl sulfoxide, N-methylpyrrolidone, polyethylene glycol dimethyl ether, etc., such as:

[0005] A study published a two-phase absorbent consisting of N-aminoethylpiperazine, n-propanol and water, in which N-aminoethylpiperazine was used as the main absorbent, n-propanol was used as the phase separator, and water was used as the solvent. The two-phase process reduced the regeneration energy consumption, but there were problems with the high volatility of n-propanol and the high viscosity of the rich liquid after phase separation.

[0006] Another study disclosed a liquid-liquid phase change absorbent for carbon dioxide capture, which is composed of primary amine, secondary amine, organic solvent and water. The primary amine refers to monoethanolamine (MEA), the secondary amine refers to 2-(ethylamino)ethanol (EAE), and the organic solvent refers to sulfolane. The absorbent has good phase separation characteristics and low energy consumption, but the degradation resistance of the secondary amine is relatively poor.

[0007] Another study disclosed an organic amine low-water absorbent for carbon dioxide capture, which is composed of 30-55% diamine, 40-67% organic solvent and 2-15% water and other additives, wherein the organic solvent is N-methylpyrrolidone. The water content in the absorbent is low, which can effectively reduce the latent heat and sensible heat of the solution.

[0008] Another study disclosed an organic amine absorbent for capturing carbon dioxide, which is prepared by uniformly mixing 10-60% main absorbent, 0-10% auxiliary absorbent, 10-80% organic solvent, 5-70% water, 0.01-5% antioxidant, and 0.01-5% anti-corrosion agent, in terms of mass percentage. The organic solvent is one or a mixture of dimethyl sulfoxide, N,N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoric triamide, N,N-dimethylacetamide, and N-methylpyrrolidone.

[0009] Another study disclosed a low-corrosive phase-change absorbent, which is composed of 10-30% of a main absorbent, 1-10% of an activator, 30-60% of a phase separator, and the remainder of water, wherein the phase separator is polyethylene glycol dimethyl ether.

[0010] In the above studies, the application of organic solvents in absorbents is prone to problems such as excessively high viscosity of the absorbent rich liquid, large evaporation of organic solvents, difficulty in controlling phase separation behavior, and high cost, which are not conducive to the long-term and stable application of the absorbent. Summary of the invention

[0011] In order to overcome at least one problem existing in the above-mentioned prior art, one of the objects of the present invention is to provide an absorbent that can effectively solve the problems of difficult phase separation, high viscosity, high volatility, high cost, etc. that are easily caused by the absorbent during application.

[0012] A second object of the present invention is to provide a method for capturing carbon dioxide.

[0013] In order to achieve the above object, the technical solution adopted by the present invention is:

[0014] The first aspect of the present invention provides an absorbent, wherein the components of the absorbent include an alcohol ether compound; the chemical formula of the alcohol ether compound is shown in formula (I):

[0015]

[0016] In formula (I), n>2; R 1 C 1 ~C 10 Alkylene; R 2 , R 3 Each independently is H or C 1 ~C 10 alkyl.

[0017] Diols contain two hydroxyl groups. The hydroxyl groups of two diol molecules can be dehydrated and etherified to form a straight-chain alcohol ether. The alcohol ether compound has a hydroxyl group at each end, which can be further dehydrated and etherified with the hydroxyl group to form alcohol ether compounds with different structures. Taking ethylene glycol as an example, the hydroxyl groups of two ethylene glycol molecules can be dehydrated and etherified to form a straight-chain diethylene glycol, also called diethylene glycol or diethylene glycol ether. Diethylene glycol has two hydroxyl groups on both sides, which can be dehydrated and etherified with the hydroxyl groups of methanol, ethanol, butanol, etc. to form diethylene glycol dimethyl ether, diethylene glycol diethyl ether, etc.; multiple ethylene glycols can form a straight-chain polyethylene glycol, and then form compounds such as polyethylene glycol dimethyl ether and polyethylene glycol diethyl ether. The common solvent polyethylene glycol dimethyl ether (NHD) comes from this.

[0018] Therefore, alcohol ether compounds can have a lot of types, but the factors that affect their physical and chemical properties as solvents are mainly: ether group, hydroxyl group, alkyl group, and long-chain molecular weight. These factors jointly affect their water solubility as solvents (for example, the more hydroxyl groups and ether groups there are, the stronger the hydrogen bonding with water, and the better the water solubility), volatility (for example, the larger the long-chain molecular weight, the higher the boiling point, and the lower the volatility), and viscosity (for example, the larger the long-chain molecular weight, the higher the viscosity). The present invention is conducive to the absorbent maintaining appropriate polarity, volatility and viscosity by designing alcohol ether compounds with suitable structures, thereby effectively improving the performance of the absorbent. In addition, alcohol ether compounds also have the advantages of low toxicity, low corrosivity, and low cost.

[0019] Preferably, in formula (I), 3≤n≤7; for example, n can be any one of 3, 4, 5, 6 or 7 or a range between any two thereof, such as 3 to 5. In some embodiments of the present invention, n is selected from 3 or 4.

[0020] The invention has a specific value of n, which is conducive to regulating the compound to have a suitable chain length and molecular weight, so that the absorbent has suitable polarity, volatility and viscosity.

[0021] In some embodiments of the present invention, n is an integer.

[0022] Preferably, in formula (I), R 1 C 1 ~C 4 Alkylene; for example R 1It can be any of methylene, ethylene, propylene or butylene. In some embodiments of the present invention, R 1 Selected from ethylene.

[0023] In some embodiments of the present invention, the absorbent is a two-phase absorbent or a single-phase absorbent.

[0024] For two-phase absorbents, alcohol ether compounds are mainly used as phase separators. At this time, they are required to be able to absorb CO before the absorbent absorbs it. 2 It remains single-phase and is miscible with aqueous solution; however, it absorbs a certain amount of CO 2 After that, it becomes immiscible with the aqueous solution and forms phase separation. Therefore, the polarity of the selected alcohol ether compound is required to be moderate to avoid no phase separation or too fast phase separation. In addition, the balance between the volatility and viscosity of the alcohol ether compound needs to be considered.

[0025] Preferably, in formula (I), R 2 and R 3 are each independently selected from C 1 ~C 10 Alkyl, or R 2 Selected from C 1 ~C 10 Alkyl, R 3 Selected from H.

[0026] By R 2 and R 3 The design makes the number of hydroxyl groups in the alcohol ether compound 0 or 1. By adjusting the number of hydroxyl groups, it is beneficial to make the alcohol ether compound have moderate polarity, thereby avoiding phase separation or phase separation too fast.

[0027] In some embodiments of the present invention, in formula (I), R 2 and R 3 are each independently selected from C 1 ~C 10 Alkyl, and R 2 The number of carbon atoms is greater than or equal to 1 and less than or equal to n-1, R 3 The number of carbon atoms is less than or equal to R 2 The number of carbon atoms; further, R 3 The number of carbon atoms is less than R 2 The number of carbon atoms.

[0028] In some embodiments of the present invention, in formula (I), R 2 Selected from C 1 ~C 10 Alkyl, R 3 Selected from H, and R 2 The number of carbon atoms is greater than or equal to 1 and less than or equal to n+2; further, R2 The number of carbon atoms is greater than or equal to 1 and less than or equal to n+1.

[0029] Through the above-mentioned structural design, the alcohol ether compounds have moderate polarity to avoid no phase separation or too fast phase separation. In addition, the volatility and viscosity of the alcohol ether compounds are balanced, which is conducive to use as a two-phase absorbent to achieve a good carbon dioxide capture effect.

[0030] For single-phase absorbents, alcohol ether compounds are used as additives. At this time, they need to be able to absorb CO in the absorbent. 2 A single phase is maintained before and after, so the selected alcohol ether compound is required to have a higher polarity. In addition, the balance between the volatility and viscosity of the alcohol ether compound needs to be considered.

[0031] Preferably, R 2 and R 3 All selected from H or R 2 Selected from C 1 ~C 10 Alkyl, R 3 Selected from H.

[0032] By R 2 and R 3 The design makes the number of hydroxyl groups in the alcohol ether compound be 1 or 2. By regulating the number of hydroxyl groups, it is beneficial to make the alcohol ether compound have a higher polarity.

[0033] In some embodiments of the present invention, in formula (I), R 2 and R 3 are each independently selected from C 1 ~C 10 Alkyl, and R 2 The number of carbon atoms is greater than or equal to 1 and less than or equal to n-2, R 3 The number of carbon atoms is greater than or equal to 1 and less than or equal to n-2; further, R 2 The number of carbon atoms is selected from 1, and / or, R 3 The number of carbon atoms is selected from 1.

[0034] In some embodiments of the present invention, in formula (I), R 2 Selected from C 1 ~C 10 Alkyl, R 3 Selected from H, and R 2 The number of carbon atoms is greater than or equal to 1 and less than or equal to n-1; further, R 2 The number of carbon atoms is selected from 1 or 2.

[0035] Through the above structural design, the alcohol ether compounds have a higher polarity, which is beneficial for their absorption of CO2 A single phase is maintained before and after, and a balance between the volatility and viscosity of alcohol ether compounds is achieved, which is conducive to use as a single-phase absorbent to achieve a good carbon dioxide capture effect.

[0036] In some embodiments of the present invention, the alcohol ether compound includes at least one of triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol dimethyl ether, triethylene glycol monomethyl ether or tetraethylene glycol monomethyl ether.

[0037] It is understandable that the above-mentioned specific alcohol ether compounds are only examples, and the present invention is not limited to the above-mentioned specific alcohol ether compounds. Those skilled in the art can freely design according to the contents described in the present invention.

[0038] Preferably, the mass percentage of the alcohol ether compound in the absorbent is 25-60%; more preferably, it is 30-55%; and even more preferably, it is 40-48%.

[0039] Preferably, the absorbent further comprises organic amine and water.

[0040] In some embodiments of the present invention, the amino group in the organic amine includes at least one of a primary amino group, a secondary amino group or a tertiary amino group.

[0041] In some embodiments of the present invention, the structure of the organic amine includes a chain or a ring.

[0042] In some embodiments of the present invention, the number of types of the organic amine is one or more.

[0043] Preferably, the absorbent comprises the following components in mass fractions: 25 to 60 parts of alcohol ether compounds, 20 to 40 parts of organic amines and 10 to 40 parts of water; further preferably, the absorbent comprises the following components in mass fractions: 30 to 55 parts of alcohol ether compounds, 22 to 38 parts of organic amines and 15 to 38 parts of water; even further preferably, the absorbent comprises the following components in mass fractions: 40 to 48 parts of alcohol ether compounds, 25 to 35 parts of organic amines and 20 to 35 parts of water.

[0044] The second aspect of the present invention provides a use of the absorbent according to the first aspect of the present invention in carbon dioxide capture.

[0045] The second aspect of the present invention provides a method for capturing carbon dioxide, comprising the following steps: using the absorbent described in the first aspect of the present invention to absorb and treat flue gas containing carbon dioxide.

[0046] Preferably, the temperature of the absorption treatment is 30-50°C; more preferably, 35-45°C.

[0047] Preferably, the absorption treatment time is 20 to 40 minutes; more preferably, it is 25 to 35 minutes.

[0048] Preferably, the volume percentage of carbon dioxide in the flue gas containing carbon dioxide is 5 to 20%; more preferably, it is 8 to 18%; and even more preferably, it is 10 to 15%.

[0049] The beneficial effects of the present invention are as follows: by regulating the ether group, hydroxyl group and alkyl structure of the alcohol ether compound so that it has suitable polarity, volatility and viscosity, and using it as a component of the absorbent, the physical and chemical properties of the absorbent can be optimized, and the absorbent has the advantages of low viscosity, low volatility, low cost and high safety, thereby having a good application effect in carbon dioxide capture. DETAILED DESCRIPTION

[0050] The content of the present invention is further described in detail below through specific examples. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can all be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0051] Some embodiments of the present invention provide an absorbent, wherein the absorbent comprises an alcohol ether compound; the chemical formula of the alcohol ether compound is shown in formula (I):

[0052]

[0053] In formula (I), n>2; R 1 C 1 ~C 10 Alkylene; R 2 , R 3 Each independently is H or C 1 ~C 10 alkyl.

[0054] In alcohol ether compounds, n is greater than 2, mainly because when n is 1 or 2, the boiling point of alcohol ether compounds is generally lower than 200°C, and the vapor pressure is relatively high, which easily leads to volatilization.

[0055] Furthermore, n does not exceed 7, mainly because when n≤7, the alcohol ether compound has a lower cost and a lower viscosity.

[0056] The boiling point, vapor pressure and evaporation enthalpy data of some alcohol ether compounds are shown in Table 1.

[0057] Table 1 Boiling point, vapor pressure and evaporation enthalpy data of some alcohol ether compounds

[0058]

[0059]

[0060] The present invention is further described below with reference to specific embodiments and comparative examples.

[0061] Example 1

[0062] An absorbent, specifically composed of 30% MEA, 40% triethylene glycol dimethyl ether and 30% water in terms of mass percentage.

[0063] Among them, n is 3 in the structure of triethylene glycol dimethyl ether; R 1 R is methylene; 2 Methyl, carbon number is 1; R 3 It is a methyl group with 1 carbon atom and 0 hydroxyl groups.

[0064] The absorbent in this example is used as a two-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 Phase separation occurs after phase separation. The ratio of light phase to rich phase is 40%:60%. The proportion of amine in the rich phase exceeds 98%. CO is absorbed in the rich phase. 2 The load after reaching 0.528 molCO 2 / mol amine, the phase separation time is less than 3min, and the viscosity of the rich phase after absorbing saturated carbon dioxide is only 13.5mPa·s (40℃).

[0065] Example 2

[0066] An absorbent comprises, by mass percentage, 30% MEA, 40% triethylene glycol monobutyl ether and 30% water.

[0067] Among them, n is 3 in the structure of triethylene glycol monobutyl ether; R 1 R is methylene; 2 It is butyl, with 4 carbon atoms; R 3 is H; the number of hydroxyl groups is 1.

[0068] The absorbent in this example is used as a two-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 Phase separation occurs after phase separation. The ratio of light phase to rich phase is 44%:56%. The proportion of amine in the rich phase exceeds 97%. CO is absorbed in the rich phase. 2 The load after reaching 0.533 molCO 2 / mol amine, the phase separation time is less than 3min, and the viscosity of the rich phase after absorbing saturated carbon dioxide is only 12.3mPa·s (40℃).

[0069] Example 3

[0070] An absorbent, specifically composed of 30% MAE, 48% tetraethylene glycol dimethyl ether and 22% water by mass percentage.

[0071] Among them, n is 4 in the structure of tetraethylene glycol dimethyl ether; R 1 R is methylene; 2 Methyl, carbon number is 1; R 3 It is a methyl group with 1 carbon atom and 0 hydroxyl groups.

[0072] The absorbent in this example is used as a two-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 Phase separation occurs after phase separation. The ratio of light phase to rich phase is 42%:58%. The proportion of amine in the rich phase exceeds 96%. CO is absorbed in the rich phase. 2 The load after reaching 0.503 molCO 2 / mol amine, the phase separation time is less than 3min, and the viscosity of the rich phase after absorbing saturated carbon dioxide is only 19.3mPa·s (40℃).

[0073] Example 4

[0074] An absorbent, specifically composed of 30% MEA, 40% triethylene glycol monomethyl ether and 30% water in terms of mass percentage.

[0075] Among them, n is 3 in the structure of triethylene glycol monomethyl ether; R 1 R is methylene; 2 Methyl, carbon number is 1; R 3 is H; the number of hydroxyl groups is 1.

[0076] The absorbent in this example is used as a single-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 After that, it still maintains a single phase, and absorbs CO in the rich phase 2 The load after reaching 0.52 molCO 2 / mol amine, the rich phase viscosity is 14.2mPa·s (40℃).

[0077] Example 5

[0078] An absorbent, specifically composed of 30% MAE, 45% tetraethylene glycol monomethyl ether and 25% water in terms of mass percentage.

[0079] Among them, n is 4 in the structure of tetraethylene glycol monomethyl ether; R 1 R is methylene; 2 Methyl, carbon number is 1; R 3 It is a methyl group with 1 carbon atom and 1 hydroxyl group.

[0080] The absorbent in this example is used as a single-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 After that, it still maintains a single phase, and absorbs CO in the rich phase 2 The load after reaching 0.51 molCO 2 / mol amine, the rich phase viscosity is 15.6mPa·s (40℃).

[0081] Comparative Example 1

[0082] An absorbent, specifically composed of 30% MEA, 40% sulfolane and 30% water by mass percentage.

[0083] The absorbent in this example is used as a two-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 Phase separation occurs after phase separation. The ratio of light phase to rich phase is 40%:60%. The proportion of amine in the rich phase exceeds 95%. CO is absorbed in the rich phase. 2 The load after reaching 0.51 molCO 2 / mol amine, the phase separation time was 5min, and the viscosity of the rich phase after absorbing saturated carbon dioxide was 22.5mPa·s (40℃).

[0084] Comparative Example 2

[0085] An absorbent, specifically composed of 30% MAE, 40% n-butanol and 30% water by mass percentage.

[0086] The absorbent in this example is used as a two-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 Phase separation occurs after phase separation. The ratio of light phase to rich phase is 46%:54%. The proportion of amine in the rich phase exceeds 90%. CO is absorbed in the rich phase. 2 The load after reaching 0.50 molCO 2 / mol amine, the phase separation time was 5min, and the viscosity of the rich phase after absorbing saturated carbon dioxide was 18.5mPa·s (40℃).

[0087] Comparative Example 3

[0088] An absorbent, specifically composed of 30% MAE, 40% N-methylpyrrolidone and 30% water by mass percentage.

[0089] The absorbent in this example is used as a single-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 After that, it still maintains a single phase, and absorbs CO in the rich phase 2 After loading 0.50 molCO 2 / mol amine, the rich phase viscosity is 17.8mPa·s (40℃).

[0090] Comparative Example 4

[0091] An absorbent, specifically composed of 30% MAE, 40% diethylene glycol monoethyl ether and 30% water by mass percentage.

[0092] Among them, n is 2 in the structure of diethylene glycol monoethyl ether; R 1 R is methylene; 2 Ethyl, carbon number is 2; R 3 is H; the number of hydroxyl groups is 1.

[0093] The absorbent in this example is used as a single-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 After that, it still maintains a single phase, and absorbs CO in the rich phase 2The load after 0.49 molCO 2 / mol amine, the rich phase viscosity is 22.8mPa·s (40℃).

[0094] Comparative Example 5

[0095] An absorbent, specifically composed of 30% MAE, 40% diethylene glycol diethyl ether and 30% water by mass percentage.

[0096] Among them, n is 2 in the structure of diethylene glycol diethyl ether; R 1 R is methylene; 2 Ethyl, carbon number is 2; R 3 It is an ethyl group with 2 carbon atoms and 0 hydroxyl groups.

[0097] The absorbent in this example is used as a two-phase absorbent and can be used for carbon dioxide capture. Specifically, the absorbent is used to absorb CO 2 The volume fraction of simulated flue gas is 12%, the absorption temperature is 40℃, and the absorption time is 30min. The absorbent absorbs CO 2 After phase separation, the ratio of light phase to rich phase is 47%:53%, and CO is absorbed in the rich phase. 2 The load after 0.49 molCO 2 / mol amine, the phase separation time was 5min, and the viscosity of the rich phase after absorbing saturated carbon dioxide was 27.6mPa·s (40℃).

[0098] Through the structural design of the above-mentioned embodiments 1 to 3, the alcohol ether compound has a moderate polarity, thereby avoiding the situation where no phase separation or too fast phase separation occurs. In addition, the volatility and viscosity of the alcohol ether compound are balanced, which is conducive to use as a two-phase absorbent and achieve a good carbon dioxide capture effect. Embodiments 1 to 3 and comparative examples 1 to 2 and 5 are all used as two-phase absorbents. In comparison, due to the appropriate structural design of embodiments 1 to 3, especially the value of n is greater than 2, the absorbent obtained has a lower viscosity and a faster phase separation time after carbon dioxide capture.

[0099] Through the structural design of the above-mentioned embodiments 4 to 5, the alcohol ether compound has a higher polarity, which is beneficial for its absorption of CO 2 A single phase is maintained before and after, and a balance between volatility and viscosity of alcohol ether compounds is achieved, which is conducive to use as a single-phase absorbent and achieves a good carbon dioxide capture effect. Examples 4 to 5 and Comparative Examples 3 to 4 are both used as single-phase absorbents. In comparison, due to the appropriate structural design, especially the value of n being greater than 2, the absorbent obtained by Examples 4 to 5 has a lower viscosity after carbon dioxide capture.

[0100] In summary, the present invention regulates the ether group, hydroxyl group and alkyl structure of the alcohol ether compound to make it have suitable polarity, volatility and viscosity, and uses it as a component of the absorbent, which can optimize the physical and chemical properties of the absorbent, and make the absorbent have the advantages of low viscosity, low volatility, low cost and high safety, thereby having a good application effect in carbon dioxide capture.

Claims

1. An absorbent, characterized in that: The absorbent comprises alcohol ether compounds; the chemical formula of the alcohol ether compounds is shown in formula (I): In formula (I), n>2; R1 is C1~C 10 Alkylene; R2, R3 are each independently H or C1~C 10 alkyl.

2. The absorbent according to claim 1, characterized in that In formula (I), 3≤n≤7; And / or, R1 is C1-C4 alkylene.

3. The absorbent according to claim 1, characterized in that In formula (I), R2 and R3 are each independently selected from C1 to C 10 Alkyl, and the number of carbon atoms of R2 is greater than or equal to 1 and less than or equal to n-1, and the number of carbon atoms of R3 is less than or equal to the number of carbon atoms of R2; Alternatively, in formula (I), R2 is selected from C1 to C 10 The alkyl group, R3 is selected from H, and the number of carbon atoms of R2 is greater than or equal to 1 and less than or equal to n+2.

4. The absorbent according to claim 1, characterized in that In formula (I), R2 and R3 are each independently selected from C1 to C 10 Alkyl, and the number of carbon atoms of R2 is greater than or equal to 1 and less than or equal to n-2, and the number of carbon atoms of R3 is greater than or equal to 1 and less than or equal to n-2; Alternatively, in formula (I), R2 is selected from C1 to C 10 The alkyl group, R3 is selected from H, and the number of carbon atoms of R2 is greater than or equal to 1 and less than or equal to n-1.

5. The absorbent according to claim 1, characterized in that The mass percentage of the alcohol ether compound in the absorbent is 25-60%.

6. The absorbent according to claim 1, characterized in that The absorbent also includes organic amine and water.

7. The absorbent according to claim 6, characterized in that The absorbent comprises the following components in parts by mass: 25 to 60 parts of alcohol ether compounds, 20 to 40 parts of organic amines and 10 to 40 parts of water.

8. Use of the absorbent according to any one of claims 1 to 7 in carbon dioxide capture.

9. A method for capturing carbon dioxide, characterized in that: The method comprises the following steps: using the absorbent described in any one of claims 1 to 7 to absorb and treat flue gas containing carbon dioxide.

10. The method for capturing carbon dioxide according to claim 9, characterized in that: The temperature of the absorption treatment is 30 to 50°C; And / or, the absorption treatment time is 20 to 40 minutes.

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