Anhydrous homogeneous absorbent for carbon dioxide capture

Abstract

The invention discloses an anhydrous homogeneous absorbent for carbon dioxide capture, and relates to the technical field of carbon dioxide emission reduction and recovery. The absorbent is a homogeneous solution formed by uniformly mixing primary / secondary amine, steric hindrance amine and an anhydrous physical solvent; compared with a traditional water-based organic amine absorbent, a physical solvent with high stability, a high boiling point, a high flash point and low specific heat is used for replacing water to serve as an organic amine auxiliary solvent for an absorption-desorption reaction. The regeneration energy consumption of the absorbent can be greatly reduced, the volatility of the absorbent is reduced, and the recycling characteristic of the absorbent is improved. The adsorbent can be used as a carbon dioxide capture absorbent for tail gas treatment of power plants, chemical plants and natural gas plants.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide emission reduction and recovery, and in particular to an anhydrous homogeneous absorbent for carbon dioxide capture. Background Art

[0002] Due to the excessive emission of greenhouse gases, global warming is becoming more and more serious. The root of solving this problem is to reduce the emission of greenhouse gases such as carbon dioxide. At present, the commonly used methods of carbon dioxide gas capture are direct air capture, pre-combustion capture, and post-combustion capture. Among them, post-combustion capture has been widely used and studied by industry and researchers due to its advantages such as no need to modify existing equipment and wide range of applications.

[0003] Post-combustion capture methods mainly include physical absorption, chemical absorption, membrane separation, and cryogenic separation. Among them, the chemical absorption method based on organic amine aqueous solution absorbent has been widely studied and applied due to its advantages such as large processing capacity, low cost, and simple absorption device. However, the alcohol amine aqueous solution absorbent currently used has problems such as high regeneration energy consumption, strong corrosion to equipment, and easy degradation. In recent years, researchers have been committed to developing new organic amine absorbents to reduce the regeneration energy consumption of rich liquid and reduce capture costs.

[0004] Using physical solvents instead of water to reduce energy consumption during regeneration is considered to be a very promising method. In the regeneration process of traditional organic amine aqueous solution absorbents, due to the large specific heat capacity and latent heat of vaporization of water, the sensible heat of warming and latent heat of vaporization of the rich liquid account for a large part of the regeneration energy consumption. Using physical solvents with high boiling point and low specific heat capacity instead of water can greatly reduce the sensible heat and latent heat in the regeneration process, while the loss of absorbent and the corrosiveness to the equipment will be reduced. The physical solvents currently used are mainly alcohols and some commonly used physical solvents. For example, CN105854529 A discloses using one or more of ethylene glycol, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and n-hexanol as physical solvents, and forming an absorbent with hindered amines and active amines. However, these alcohol solvents have problems such as low flash point of alcohols, strong volatility, and large solvent loss, and the energy consumption is still high due to more solvent evaporation during regeneration. Summary of the invention

[0005] The object of the present invention is to solve the above problems in the prior art and to provide an anhydrous homogeneous absorbent for carbon dioxide capture which has high safety, low regeneration energy consumption, low corrosiveness and good absorption-desorption performance.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A water-free homogeneous absorbent for carbon dioxide capture, wherein the water-free homogeneous absorbent is a homogeneous solution formed by uniformly mixing primary / secondary amines, sterically hindered amines and anhydrous physical solvents; the anhydrous physical solvent is at least one of diethylene glycol monoethyl ether and polyethylene glycol dimethyl ether.

[0008] The primary / secondary amine includes at least one of monoethanolamine, diethanolamine, hydroxyethylethylenediamine and piperazine.

[0009] The sterically hindered amine is 2-amino-2-methyl-1-propanol.

[0010] The mass percentages of the primary / secondary amine, the sterically hindered amine and the anhydrous physical solvent are 5% to 25%, 10% to 25% and 50% to 85% respectively.

[0011] The anhydrous homogeneous absorbent is used for capturing carbon dioxide.

[0012] Specifically, carbon dioxide gas is introduced into the anhydrous homogeneous absorbent and absorbed at a certain temperature. After the anhydrous homogeneous absorbent is saturated with carbon dioxide, it is heated to a certain temperature to desorb carbon dioxide, so that the absorbent is regenerated.

[0013] The temperature for absorbing carbon dioxide may be 30-50°C.

[0014] The temperature for desorbing carbon dioxide may be 80-130°C.

[0015] The anhydrous homogeneous absorbent still maintains a homogeneous phase solution after absorbing carbon dioxide to saturation.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0017] In the anhydrous homogeneous absorbent formulation of the present invention, a high boiling point physical solvent is used instead of water, which can greatly reduce the energy consumption in the regeneration process. The solvent has a high flash point, is difficult to volatilize, and has high safety. The primary / secondary amine in the absorbent provides a faster absorption rate for the absorption reaction, and the sterically hindered amine ensures a higher carbon dioxide absorption capacity and desorption capacity. The absorbent of the present invention is less corrosive to carbon steel than traditional water-based absorbents. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with embodiments.

[0019] Example 1

[0020] A water-free absorbent for carbon dioxide capture is composed of hydroxyethylethylenediamine, 2-amino-2-methyl-1-propanol and diethylene glycol monoethyl ether which are uniformly mixed, and the mass percentage of each component is as follows: 10% hydroxyethylethylenediamine, 20% 2-amino-2-methyl-1-propanol, and 70% diethylene glycol monoethyl ether.

[0021] Example 2

[0022] A water-free absorbent for carbon dioxide capture is composed of a uniform mixture of monoethanolamine, 2-amino-2-methyl-1-propanol and diethylene glycol monoethyl ether, wherein the mass percentage of each component is as follows: 10% monoethanolamine, 20% 2-amino-2-methyl-1-propanol, and 70% diethylene glycol monoethyl ether.

[0023] Example 3

[0024] A water-free absorbent for carbon dioxide capture is composed of hydroxyethylethylenediamine, 2-amino-2-methyl-1-propanol and diethylene glycol monoethyl ether which are uniformly mixed, and the mass percentage of each component is as follows: 5% hydroxyethylethylenediamine, 25% 2-amino-2-methyl-1-propanol, and 70% diethylene glycol monoethyl ether.

[0025] Example 4

[0026] A water-free absorbent for carbon dioxide capture is composed of a uniform mixture of monoethanolamine, 2-amino-2-methyl-1-propanol and diethylene glycol monoethyl ether, wherein the mass percentage of each component is as follows: 5% monoethanolamine, 25% 2-amino-2-methyl-1-propanol, and 70% diethylene glycol monoethyl ether.

[0027] Example 5

[0028] A water-free absorbent for carbon dioxide capture is composed of a uniform mixture of monoethanolamine, 2-amino-2-methyl-1-propanol and diethylene glycol monoethyl ether, wherein the mass percentage of each component is as follows: 5% monoethanolamine, 15% 2-amino-2-methyl-1-propanol, and 80% diethylene glycol monoethyl ether.

[0029] Example 6

[0030] A water-free absorbent for carbon dioxide capture is composed of hydroxyethylethylenediamine, 2-amino-2-methyl-1-propanol and diethylene glycol monoethyl ether which are uniformly mixed, and the mass percentage of each component is as follows: 5% hydroxyethylethylenediamine, 15% 2-amino-2-methyl-1-propanol, and 80% diethylene glycol monoethyl ether.

[0031] Example 7

[0032] A water-free absorbent for carbon dioxide capture is composed of a uniform mixture of monoethanolamine, 2-amino-2-methyl-1-propanol and diethylene glycol monoethyl ether, wherein the mass percentage of each component is as follows: 30% of monoethanolamine, 10% of 2-amino-2-methyl-1-propanol and 60% of diethylene glycol monoethyl ether.

[0033] Comparative Example 1

[0034] A water-based absorbent is composed of monoethanolamine and water uniformly mixed, and the mass percentages of the components are as follows: 30% monoethanolamine and 70% water.

[0035] Comparative Example 2

[0036] A water-based absorbent is prepared by uniformly mixing hydroxyethylethylenediamine, 2-amino-2-methyl-1-propanol and water, wherein the mass percentages of the components are as follows: 10% hydroxyethylethylenediamine, 20% 2-amino-2-methyl-1-propanol and 70% water.

[0037] Test results

[0038] (1) For Examples 1 to 7 and Comparative Examples 1 to 2, the prepared solutions were respectively placed in absorption bottles and placed in a water bath for heat preservation; dry carbon dioxide gas was introduced into the absorption bottle for absorption at 40°C, and its inlet flow rate was controlled by a mass flow meter. A soap film flow meter was set at the outlet of the absorption bottle to detect the outlet flow rate. When the outlet flow rate of the absorption bottle was equal to the inlet flow rate, the absorption was considered to be saturated. The carbon dioxide content in the saturated absorption liquid was detected.

[0039] (2) After the absorbents described in Examples 1 to 7 and Comparative Examples 1 to 2 were saturated with carbon dioxide, they were placed in a constant temperature oil bath for heating and regeneration to desorb carbon dioxide at a desorption temperature of 120° C. for 1 hour. The residual carbon dioxide in the regenerated absorbent was detected.

[0040] Table 1

[0041]

[0042] It can be seen from Table 1 that the absorbent of Example 1 has better absorption-desorption performance than other examples.

[0043] (3) The regeneration energy consumption of Example 1 and Comparative Example 1 was estimated. The regeneration energy consumption includes desorption reaction heat, sensible heat of heating, and latent heat of vaporization. The regeneration energy consumption data are shown in Table 2. The regeneration energy consumption of the composite amine-methanol absorbent of patent CN105854529 A is 2.71 GJ / t CO2. It can be seen from Table 2 that the regeneration energy consumption of the anhydrous homogeneous absorbent of the present invention is much lower than that of the water-based absorbent, and the energy consumption of the present invention is also lower than that of the composite amine-methanol absorbent.

[0044] Table 2

[0045]

[0046] (4) The corrosion rates of the saturated absorbents of Example 1 and Comparative Example 1 on carbon steel coupons at room temperature were measured respectively. The results showed that after the absorbent was saturated with carbon dioxide, the corrosion rate of the anhydrous amine-based absorbent of Example 1 on carbon steel was only 5.6% of that of the absorbent of Comparative Example 1.

[0047] The above embodiments are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. An anhydrous homogeneous absorbent for carbon dioxide capture, characterized in that: The anhydrous homogeneous absorbent is a homogeneous solution formed by uniformly mixing primary / secondary amine, sterically hindered amine and anhydrous physical solvent; the anhydrous physical solvent is at least one of diethylene glycol monoethyl ether and polyethylene glycol dimethyl ether.

2. The anhydrous homogeneous absorbent for carbon dioxide capture according to claim 1, characterized in that: The primary / secondary amine includes at least one of monoethanolamine, diethanolamine, hydroxyethylethylenediamine and piperazine.

3. The anhydrous homogeneous absorbent for carbon dioxide capture according to claim 1, characterized in that: The sterically hindered amine is 2-amino-2-methyl-1-propanol.

4. The anhydrous homogeneous absorbent for carbon dioxide capture according to claim 1, characterized in that: The mass percentages of the primary / secondary amine, the sterically hindered amine and the anhydrous physical solvent are 5% to 25%, 10% to 25% and 50% to 85% respectively.

5. The use of an anhydrous homogeneous absorbent for carbon dioxide capture according to any one of claims 1 to 4, characterized in that: For the capture of carbon dioxide.

6. The use according to claim 5, characterized in that: Carbon dioxide gas is introduced into the anhydrous homogeneous absorbent and absorbed at a certain temperature. After the anhydrous homogeneous absorbent is saturated with carbon dioxide, it is heated to a certain temperature to desorb carbon dioxide, so that the absorbent is regenerated.

7. The use according to claim 6, characterized in that: The temperature for absorbing carbon dioxide is 30-50°C.

8. The use according to claim 6, characterized in that: The temperature for desorbing carbon dioxide is 80-130°C.

9. The use according to claim 6, characterized in that: The anhydrous homogeneous absorbent still maintains a homogeneous phase solution after absorbing carbon dioxide to saturation.

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