Low-temperature regenerated non-aqueous phase absorbent for carbon dioxide capture

Abstract

The invention discloses a low-temperature regenerated non-aqueous phase absorbent for carbon dioxide capture, and belongs to the technical field of carbon dioxide capture and separation, the absorbent is mainly composed of steric hindrance amine and an organic solvent, the steric hindrance amine is an absorption component, the molar concentration of the steric hindrance amine is 1-5 mol / L, and the organic solvent partially participates in the reaction while serving as the solvent. The non-aqueous phase absorption system prepared by the invention can realize low-temperature and high-efficiency regeneration of the absorbent under the condition of not adding any catalyst, and has high absorption rate and CO2 loading at the same time. The low-temperature regenerated absorbent can realize utilization of low-grade heat of the power plant, so that the power generation cost of the power plant additionally provided with the carbon capture system is greatly reduced, and a foundation is laid for further popularization of the carbon capture system.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture and separation, and in particular relates to a low-temperature regenerated non-aqueous phase absorbent for carbon dioxide capture. Background Art

[0002] Carbon dioxide capture, utilization and storage (CCUS) is a technology for fixing CO2 in thermal power generation, steelmaking, limestone calcination, etc. 2 Emission source process proven CO 2 Capture technology. Among them, organic amine absorbent is the most widely used chemical absorbent in industry. However, the high regeneration energy consumption of current organic amine absorbents limits their further promotion.

[0003] The regeneration energy consumption of the absorbent is mainly composed of three parts: absorbent and CO 2 The heat of reaction, the sensible heat used to heat up the absorbent, and the latent heat caused by the partial volatilization of the absorbent. At present, the regeneration of absorbents is carried out at a high temperature of about 120°C, which means that the regeneration process needs to provide heat through steam, which will reduce the power generation efficiency of the power plant. If the low-temperature regeneration of the absorbent (less than 100°C) can be achieved, the absorbent can be regenerated only by the low-grade waste heat of the power plant, which will greatly reduce the regeneration energy consumption of the absorbent, reduce the regeneration cost, and promote the further promotion of carbon capture technology.

[0004] The high energy consumption of organic amine absorbent regeneration limits the industrial development of absorbents. It is urgent to build an absorption system that can achieve low-temperature regeneration to adapt to CO2 fixation in thermal power plants and other 2 Emission sources, promote large-scale industrial application of carbon capture technology. At present, some organic amine absorbents can be regenerated at low temperature by adding catalysts, but this method often has problems such as high cost, low regeneration efficiency, catalyst deactivation and clogging. Summary of the invention

[0005] Purpose of the invention: In order to further promote the large-scale application of carbon capture technology, the present invention provides a low-temperature regenerated non-aqueous phase absorbent for carbon dioxide capture, so as to achieve low-temperature regeneration of the absorbent and reduce the cost of carbon capture.

[0006] Invention content: To achieve the above-mentioned purpose, the present invention provides a low-temperature regenerated non-aqueous phase absorbent for carbon dioxide capture, which is mainly composed of two parts: a sterically hindered amine and an organic solvent, wherein the sterically hindered amine is an absorption component with a molar concentration of 1 to 5 mol / L, and the organic solution acts as a solvent and partially participates in the reaction.

[0007] The present invention uses sterically hindered amines to capture CO 2The unstable products formed after further react with the organic solvent to convert them into easily decomposable products, thereby increasing the absorption load of the absorbent and reducing the release of CO 2 In addition, the non-aqueous phase absorbent uses an organic solution with a high boiling point and low specific heat capacity instead of water as a solvent, which can reduce the regeneration sensible heat and latent heat, and has a great energy-saving advantage.

[0008] Preferably, the organic solvent is ethylene glycol. As an organic solvent, ethylene glycol has the advantages of high boiling point and low specific heat capacity, which can reduce the sensible heat and latent heat of regeneration. On the other hand, it can further react with the intermediate product to convert it into an easily decomposable product, thereby increasing the absorption load of the absorbent and reducing the release of CO. 2 In contrast, although other alcohols can also achieve the effect of low-temperature regeneration, ethanol has a low boiling point and is highly volatile, while other polyhydroxy alcohols have high viscosity, which is not conducive to industrial application.

[0009] Preferably, the sterically hindered amine comprises a primary amine having three substituents on the α carbon, and / or a secondary amine having two / three substituents on the α carbon.

[0010] Specifically, the sterically hindered amine includes one or more of 2-(isopropylamino)ethanol, 2-(tert-butylamino)ethanol, tert-octylamine, 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, tris(hydroxymethyl)aminomethane, N-methylcyclohexylamine, 2-methylpiperidine, and 2-methylpiperazine.

[0011] Specifically, the absorption temperature of the absorbent is 30-50°C.

[0012] Specifically, the absorbent is regenerated by thermal desorption, and the regeneration temperature is 70-100°C.

[0013] Specifically, the absorbent absorbs CO 2 The solution is homogeneous and clear, and no liquid-liquid or solid-liquid phase change occurs. Compared with phase change absorbents, the non-aqueous phase absorption system prepared by the present invention is suitable for existing carbon capture equipment, and no additional process development is required, which greatly reduces the equipment cost.

[0014] Beneficial effects: The non-aqueous phase absorption system prepared by the present invention can realize low-temperature and high-efficiency regeneration of the absorbent without adding any catalyst, and has both high absorption rate and CO 2 Low-temperature regenerated absorbents can make use of low-grade heat from power plants, thereby greatly reducing the power generation costs of power plants that have added carbon capture systems, laying the foundation for further promotion of carbon capture systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 In the embodiment of the present invention, the non-aqueous phase absorbent is used to capture CO 2 Schematic diagram of the reaction in the process;

[0016] Figure 2 CO is the CO of the non-aqueous phase absorbent and the ethanolamine aqueous solution in Example 1 of the present invention. 2 Load comparison chart;

[0017] Figure 3 (a) and (b) are respectively the absorption of CO by the non-aqueous phase absorbent in Example 1 of the present invention. 2 Before and after acquisition images;

[0018] Figure 4 is the CO of the non-aqueous phase absorbent at different concentrations in Example 2 of the present invention 2 Load comparison chart;

[0019] Figure 5 CO is the CO of the non-aqueous phase absorbent in the cyclic absorption-desorption experiment in Example 3 of the present invention. 2 Load variation curve. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0021] This embodiment provides a low-temperature regenerative non-aqueous phase absorbent for carbon dioxide capture, which is prepared by mixing a sterically hindered amine and ethylene glycol, wherein the sterically hindered amine is an absorption component with a molar concentration of 1 to 5 mol / L, and ethylene glycol acts as an organic solvent and partially participates in the reaction.

[0022] like Figure 1 As shown, the present invention utilizes the steric hindrance effect of amine molecules to allow amine molecules to capture CO 2 After that, the formation of unstable intermediates, such as zwitterions or carbamates, can further react with ethylene glycol, releasing the amine sites, which can further react with CO 2 reaction, increasing the absorption load of the absorbent, and at the same time the new product released CO 2 The required energy barrier is much smaller than that of the original product. In addition, the non-aqueous phase absorbent uses an organic solution with a high boiling point and low specific heat capacity instead of water as a solvent, which can reduce the regeneration sensible heat and latent heat, and has a great energy-saving advantage.

[0023] Preferably, the sterically hindered amine includes a primary amine with three substituents on the α carbon, and / or a secondary amine with two / three substituents on the α carbon. Specifically, the sterically hindered amine includes one or more of 2-(isopropylamino)ethanol, 2-(tert-butylamino)ethanol, tert-octylamine, 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, tris(hydroxymethyl)aminomethane, N-methylcyclohexylamine, 2-methylpiperidine, and 2-methylpiperazine.

[0024] Specifically, the absorbent achieves CO 2 The capture conditions include: absorption temperature of 30-50°C and regeneration temperature of 70-100°C. 2 Both before and after are homogeneous clear solutions, and no liquid-liquid or solid-liquid phase transition occurs.

[0025] Embodiment 1:

[0026] Taking N-methylcyclohexylamine as the absorption component, non-aqueous phase absorbents with a concentration of 1 mol / L were prepared respectively, and compared with 1 mol / L ethanolamine (MEA) aqueous solution under the same conditions. The test results are as follows: Figure 2 As shown. It can be seen that the CO 2 The loading is as high as 0.86 mol / L, which is about 1.65 times that of MEA aqueous solution.

[0027] At the same time, the absorbent absorbs CO 2 The states before and after absorption saturation are as follows Figure 3 As shown in Figures 3(a) and 3(b), it can be seen that the absorbent always maintains a homogeneous clear state without any liquid-liquid or solid-liquid phase change.

[0028] Embodiment 2:

[0029] Taking N-methylcyclohexylamine as the absorption component, non-aqueous phase absorbents with concentrations of 1 to 5 mol / L were prepared respectively. The CO 2 Load as Figure 4 shown.

[0030] It can be seen that the absorption load of the absorbent at a concentration of 1 mol / L is 0.86 mol / L, which is much higher than the theoretical load of 0.5 mol / L. This shows that the organic solvent ethylene glycol not only acts as a solvent, but also partially participates in the reaction and promotes absorption. At the same time, as the concentration of the absorption component increases, the absorbent load increases from 0.86 mol / L to more than 2.00 mol / L, which obviously has a higher CO 2 load.

[0031] Embodiment 3:

[0032] N-methylcyclohexylamine was used as the absorption component, and a non-aqueous phase absorbent with a concentration of 3 mol / L was prepared. The absorbent was subjected to a cyclic absorption-desorption experiment under the conditions of absorption at 40°C for 30 min and desorption at 80°C for 25 min. The cyclic results are shown in the following table. Figure 5 It can be seen that the absorbent can maintain stable circulation under this condition, and the load of the fourth cycle is still 30wt% MEA / H 2 O solution initial regeneration load is 2.82 times.

[0033] In summary, the present invention does not require the addition of a catalyst and can achieve low-temperature regeneration only through the properties of the absorbent itself. At the same time, the absorbent cost and equipment modification cost are low, and the viscosity of the final saturated solution is low, which is conducive to promoting the large-scale application of carbon capture technology.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low temperature regenerative non-aqueous phase absorbent for carbon dioxide capture, characterized in that: The invention comprises a sterically hindered amine and an organic solvent, wherein the sterically hindered amine is an absorption component and its molar concentration is 1-5 mol / L.

2. The low-temperature regenerated non-aqueous phase absorbent according to claim 1, characterized in that: The organic solvent is ethylene glycol.

3. The low-temperature regenerated non-aqueous phase absorbent according to claim 1, characterized in that: The sterically hindered amines include primary amines having three substituents on the α carbon, and / or secondary amines having two / three substituents on the α carbon.

4. The low-temperature regenerated non-aqueous phase absorbent according to claim 1, characterized in that: The sterically hindered amine includes one or more of 2-(isopropylamino)ethanol, 2-(tert-butylamino)ethanol, tert-octylamine, 2-amino-2-methyl-1-propanol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-ethyl-1,3-propanediol, tris(hydroxymethyl)aminomethane, N-methylcyclohexylamine, 2-methylpiperidine, and 2-methylpiperazine.

5. The low-temperature regenerated non-aqueous phase absorbent according to claim 1, characterized in that: The absorption temperature of the absorbent is 30-50°C.

6. The low-temperature regenerated non-aqueous phase absorbent according to claim 1, characterized in that: The absorbent is regenerated by thermal desorption, and the regeneration temperature is 70-100°C.

7. The low-temperature regenerated non-aqueous phase absorbent according to claim 1, characterized in that: The absorbent is a homogeneous clear solution before and after absorbing CO2.

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