A liquid phase autocatalytic regeneration absorbent and its application in capturing carbon dioxide

Abstract

The present invention discloses a liquid-phase self-catalytic regenerable absorbent and its application in carbon dioxide capture, which relates to the technical field of carbon dioxide emission reduction. The raw materials of the liquid-phase self-catalytic regenerable absorbent of the present invention are composed of the following components in mass percentage: 20-50% of organic amine, 40-80% of water, and 0-30% of proton transfer agent, and the content of the proton transfer agent is not 0%; wherein, the organic amine is a water-soluble organic amine, the proton transfer agent is immiscible with the organic amine, and the proton transfer agent is a reagent with proton transfer function and 16 < pKa < 8. The present invention solves the problems existing in the prior art such as low catalytic efficiency of the absorbent, high regeneration energy consumption, catalyst deactivation, etc., thereby enhancing the regeneration kinetics of the organic amine solution and reducing the regeneration energy consumption of the organic amine solution.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide emission reduction, and particularly to a liquid-phase self-catalytic regenerable absorbent and its application in carbon dioxide capture. Background Art

[0002] With the extensive use of fossil fuels and the increase in industrial activities, the concentration of greenhouse gases in the atmosphere has been continuously rising, which has become the main driving force for global warming. Among greenhouse gases, the impact of carbon dioxide is particularly significant.

[0003] To mitigate the negative impacts brought about by climate change, carbon capture, utilization, and storage (CCUS) technologies are considered a solution with industrial application potential. Among various CCUS technologies, the chemical absorption method has attracted much attention due to its strong selectivity and wide application range, and has become one of the mainstream technologies for post-combustion carbon dioxide capture. However, the chemical absorption method faces the challenge of high energy consumption during the regeneration process, which has become a problem that needs to be solved urgently.

[0004] To solve the problem of excessive regeneration energy consumption, methods such as compound phase change absorbents and adding catalysts are mainly adopted at present. However, the phase change absorbents have complex components and are prone to degradation; after the catalysts are put back into use, the technical means are cumbersome and additives are required, etc., which may lead to unsatisfactory effects. Therefore, it is particularly necessary to provide a desorption and regeneration method with simple method and excellent effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a liquid-phase self-catalytic regenerable absorbent and its application in carbon dioxide capture to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention: Provide a liquid-phase self-catalytic regenerable absorbent, the raw materials of which are composed of the following components in mass percentage:

[0008] Organic amine 20 - 50%, water 40 - 80%, and proton transfer agent 0 - 30%, and the content of the proton transfer agent is not 0%;

[0009] The organic amine is a water-soluble organic amine; the proton transfer agent is immiscible with the organic amine;

[0010] The proton transfer agent is a reagent with a proton transfer effect having 16 < pKa < 8.

[0011] As a further preference of the present invention, the organic amine is one or more of ethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, and piperazine.

[0012] As a further preference of the present invention, the proton transfer agent is one or more of phenolic, alcoholic or carboxylic organic compounds.

[0013] Technical solution two of the present invention: Provide the application of the above-mentioned liquid-phase self-catalytic regenerated absorbent in carbon dioxide capture.

[0014] Technical solution three of the present invention: Provide the application of a proton transfer agent in recovering a carbon dioxide absorbent, the carbon dioxide absorbent being a water-soluble organic amine, and the proton transfer agent being immiscible with the organic amine; the proton transfer agent is a reagent with a proton transfer effect having 16 < pKa < 8.

[0015] Technical solution four of the present invention: Provide a self-catalytic regeneration method for a carbon dioxide absorbent, comprising the following steps:

[0016] Add a proton transfer agent to an aqueous solution of an organic amine that has absorbed carbon dioxide, heat and regenerate the resulting mixture, then let it stand for phase separation, and separate the aqueous phase of the organic amine solution and the proton transfer agent phase to achieve self-catalytic regeneration of the carbon dioxide absorbent;

[0017] The proton transfer agent is immiscible with the organic amine; the proton transfer agent is a reagent with a proton transfer effect having 16 < pKa < 8.

[0018] As a further preference of the present invention, the temperature of the heat regeneration is 70 - 100 °C, and the time is 100 - 250 min.

[0019] As a further preference of the present invention, the mass ratio of the organic amine to the proton transfer agent in the aqueous solution of the organic amine is 20 - 50:0 - 30, and the mass of the proton transfer agent is not 0.

[0020] The present invention adds a proton transfer agent to the rich solution of the organic amine that has adsorbed carbon dioxide, heats and regenerates it after sufficient mixing, then cools and stands still to complete the phase separation of the proton transfer agent and the lean solution of the organic amine, thereby separating the lean solution of the organic amine and the proton transfer agent to complete the regeneration of the absorbent.

[0021] During the heat regeneration process of the carbon dioxide absorbent of the present invention, an increase in temperature can enable the proton transfer agent to provide protons for the regeneration of the organic amine solution, playing a homogeneous catalytic role and ensuring the regeneration effect of the organic amine solution. However, too high a pKa is not conducive to the occurrence of proton transfer, and too low a pKa causes the proton transfer agent to directly react with the absorbent solution, reducing the pKa of the absorbent solution and making it unable to be recycled.

[0022] The present invention discloses the following technical effects:

[0023] The present invention adopts a proton transfer agent which is incompatible with an organic amine carbon dioxide absorbent to replace the protonated amine to provide protons during the regeneration process, thereby promoting the rate-controlling step of the organic amine regeneration process. The proton transfer agent can be separated from the organic amine solution after regeneration, and the catalytic organic amine regeneration can be completed without affecting the absorption process.

[0024] The invention solves the problems of low absorbent catalytic efficiency, high regeneration energy consumption, catalyst deactivation and the like in the prior art, thereby enhancing the regeneration kinetics of the organic amine solution and reducing the regeneration energy consumption of the organic amine solution. DETAILED DESCRIPTION

[0025] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0026] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0028] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0029] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0030] Example 1

[0031] A liquid phase self-catalytic regeneration absorbent, the raw material mass percentage is as follows:

[0032] Ethanolamine (MEA) 30%, water 60% and phenol (pKa=9.97) 10%.

[0033] The absorption of carbon dioxide and the regeneration process of the absorbent are as follows:

[0034] (1) Absorption of carbon dioxide: dissolving ethanolamine in water, and using the obtained ethanolamine solution to absorb carbon dioxide gas until saturation to obtain an organic amine rich solution;

[0035] (2) Regeneration of the absorbent: Phenol is added to the obtained organic amine rich solution, and after sufficient mixing, the mixture is heated to 90°C for 180 min to complete the regeneration. The mixture is then cooled and allowed to stand to allow the proton transfer agent phenol and the organic amine lean solution to separate into phases, thereby separating the proton transfer agent and the organic amine lean solution (the volume ratio of the upper and lower liquid phases is 1:9, with the upper phase being phenol and the lower phase being the organic amine lean solution), thereby completing the regeneration of the adsorbent.

[0036] The maximum desorption rate of carbon dioxide during the regeneration process reached 3.70mmol / min.

[0037] Example 2

[0038] A liquid phase self-catalytic regeneration absorbent, the raw material mass percentage is as follows:

[0039] Ethanolamine (MEA) 30%, water 60% and cresol (pKa=10.20) 10%; wherein, cresol (CAS: 1319-77-3).

[0040] (1) Absorption of carbon dioxide: dissolving ethanolamine in water, and using the obtained ethanolamine solution to absorb carbon dioxide gas until saturation to obtain an organic amine rich solution;

[0041] (2) Regeneration of the absorbent: cresol is added to the obtained organic amine rich solution, and after sufficient mixing, the mixture is heated to 90°C for 180 min to complete the regeneration. The mixture is then cooled and allowed to stand to allow the proton transfer agent cresol and the organic amine lean solution to separate into phases, thereby separating the proton transfer agent and the organic amine lean solution (the volume ratio of the upper and lower liquid phases is 1:9, with the upper phase being cresol and the lower phase being the organic amine lean solution), thereby completing the regeneration of the adsorbent.

[0042] The maximum desorption rate of carbon dioxide during the regeneration process reached 5.09mmol / min.

[0043] Comparative Example 1

[0044] A carbon dioxide absorbent, the raw material mass percentage is as follows:

[0045] Ethanolamine (MEA) 30% and water 70%.

[0046] Ethanolamine was dissolved in water, the obtained ethanolamine aqueous solution absorbed carbon dioxide until saturated, and the obtained organic amine rich solution was heated to 90°C for 180 minutes to complete the regeneration. The maximum desorption rate was 2.13 mmol / min.

[0047] Comparative Example 2

[0048] A carbon dioxide absorbent, the raw material mass percentage is as follows:

[0049] Ethanolamine (MEA) 30%, water 60% and formic acid (pKa=3.57) 10%.

[0050] (1) Absorption of carbon dioxide: dissolving ethanolamine in water, and using the obtained ethanolamine solution to absorb carbon dioxide gas until saturation to obtain an organic amine rich solution;

[0051] (2) Regeneration of absorbent: Add formic acid to the obtained organic amine rich solution, mix thoroughly and heat to 90°C for 180 minutes to complete the regeneration. Since formic acid is easily soluble in water, there is no phase separation after regeneration. Since formic acid has a low pKa, it reacts directly with the absorption liquid, reducing the pKa of the absorption liquid, resulting in the absorption liquid being unable to be recycled. The maximum carbon dioxide desorption rate is 0.50mmol / min.

[0052] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for autocatalytic regeneration of a carbon dioxide absorbent, characterized in that: It includes the following steps: Adding a proton transfer agent to the aqueous solution of organic amine that absorbs carbon dioxide, heating and regenerating the obtained mixture, then standing for stratification, and separating the aqueous phase of organic amine and the phase of proton transfer agent to achieve the autocatalytic regeneration of the carbon dioxide absorbent; The organic amine is one or more of ethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, and piperazine; The proton transfer agent is immiscible with the organic amine; the proton transfer agent is a reagent with proton transfer function having 8 < pKa < 16; the proton transfer agent is a phenol; The temperature of the heating regeneration is 70 - 100 °C, and the time is 100 - 250 min; The mass ratio of the organic amine in the aqueous solution of organic amine to the proton transfer agent is 20 - 50:0 - 30, and the mass of the proton transfer agent is not 0.