Liquid-phase autocatalytic regenerative absorbent and its application in carbon dioxide recovery

Abstract

The present invention provides a liquid-phase autocatalytic regenerative absorbent. [Solution] The raw materials for the liquid-phase autocatalytic regenerative absorbent of the present invention consist of the following components in the following mass fractions: organic amine 20-50%, water 40-80%, proton transfer agent 0-30%, and the content of the proton transfer agent is not 0%, where the organic amine is a water-soluble organic amine, the proton transfer agent is insoluble with the organic amine, and the proton transfer agent is 8

Description

Technical Field

[0001] The present invention relates to the field of carbon dioxide emission reduction technology, and particularly relates to a liquid-phase self-catalytic regeneration absorbent and its application in carbon dioxide recovery.

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 a major factor in global warming. Among greenhouse gases, the impact of carbon dioxide is particularly significant.

[0003] To mitigate the negative impacts of climate change, carbon dioxide capture, utilization, and storage (CCUS) technologies have attracted attention as potential solutions for industrial applications. Among various CCUS technologies, the chemical absorption method has high selectivity and a wide application range, and thus has become one of the mainstream technologies for post-combustion carbon dioxide capture. However, the chemical absorption method faces the problem of high energy consumption in the regeneration process, which urgently needs to be solved.

[0004] To solve the problem of excessive consumption of renewable energy, currently, mainly methods such as using composite phase change absorbents and adding catalysts are adopted. However, phase change absorbents have complex components and are prone to decomposition, and catalysts are technically complicated during reuse and require additives, etc., so the effect may be insufficient. Therefore, it is particularly necessary to provide a desorption regeneration method with simple operation and excellent effect.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the present invention is to provide a liquid-phase self-catalytic regeneration absorbent and its application in carbon dioxide recovery in order to solve the problems of the above-mentioned prior art.

Means for Solving the Problems

[0006] To achieve the above object, the present invention provides the following solutions.

[0007] The first technical scheme of the present invention is to provide a liquid-phase self-catalytic regenerable absorbent, and the raw material is composed of components with the following mass fractions: Organic amine 20 - 50%, water 40 - 80%, proton transfer agent 0 - 30%, and the content of the proton transfer agent is not 0%, The organic amine is a water-soluble organic amine, and the proton transfer agent is insoluble with the organic amine, The proton transfer agent is a reagent having a proton transfer effect with 8 < pKa < 16.

[0008] In a more preferred embodiment of the present invention, the organic amine is one or more of ethanolamine, diethanolamine, triethanolamine, diethylenetriamine, triethylenetetramine, and piperazine.

[0009] In a more preferred embodiment of the present invention, the proton transfer agent is one or more of phenols, alcohols, or carboxylic acid organic substances.

[0010] The second technical scheme of the present invention provides an application of the above liquid-phase self-catalytic regenerable absorbent in carbon dioxide recovery.

[0011] The third technical scheme of the present invention provides an application of the proton transfer agent in the recovery of a carbon dioxide absorbent. The carbon dioxide absorbent is a water-soluble organic amine, and the proton transfer agent is insoluble with the organic amine. The proton transfer agent is a reagent having a proton transfer effect with 8 < pKa < 16.

[0012] The fourth technical scheme of the present invention provides a self-catalytic regeneration method for a carbon dioxide absorbent, A step of realizing self-catalytic regeneration of the carbon dioxide absorbent is included, which is to add a proton transfer agent to an aqueous organic amine solution that has absorbed carbon dioxide, heat and regenerate the resulting mixture, then allow it to stand and separate into layers, and separate the aqueous organic amine solution phase and the proton transfer agent phase. The proton transfer agent is immiscible with the organic amine, and the proton transfer agent is a reagent having a proton transfer effect with 8 < pKa < 16.

[0013] In a more preferred embodiment of the present invention, the temperature of the heat regeneration is 70 - 100 °C and the time is 100 - 250 min.

[0014] In a more preferred embodiment of the present invention, the mass ratio of the organic amine to the proton transfer agent in the aqueous organic amine solution is 20 - 50:0 - 30, and the mass of the proton transfer agent is not zero.

[0015] In the present invention, a proton transfer agent is added to the organic amine-rich liquid that has adsorbed carbon dioxide, mixed well, then heat regeneration is carried out, and then cooled and allowed to stand to complete the phase separation of the proton transfer agent and the organic amine-lean liquid, thereby separating the organic amine-lean liquid and the proton transfer agent and completing the regeneration of the absorbent.

[0016] In the process of heat regeneration of the carbon dioxide absorbent in the present invention, as the temperature rises, the proton transfer agent provides protons for the regeneration of the organic amine solution and plays a homogeneous phase catalytic role, thereby ensuring the regeneration effect of the organic amine solution. However, if the pKa is too high, proton transfer is difficult to occur, and if the pKa is too low, the proton transfer agent reacts directly with the absorbent solution to lower the pKa of the absorbent solution, making recycling impossible.

Effects of the Invention

[0017] The present invention discloses the following technical effects.

[0018] This invention employs a proton transfer agent that is insoluble with an organic amine carbon dioxide absorbent, providing protons in place of the protonated amine during the regeneration process and accelerating the rate control step of the organic amine regeneration process. After the regeneration of the organic amine, the proton transfer agent can be separated from the organic amine solution, and the catalyst for organic amine regeneration can be completed without affecting the absorption process.

[0019] This invention solves the problems of conventional technology, such as reduced catalytic efficiency of absorbents, high energy consumption for regeneration, and catalyst deactivation, thereby improving the regeneration kinetics of organic amine solutions and reducing the energy consumption required for regeneration of organic amine solutions. [Modes for carrying out the invention]

[0020] Various exemplary embodiments of the present invention will be described in detail, but this detailed description should not be construed as limiting the invention, but rather as a more detailed description of specific aspects, features, and examples of the invention.

[0021] It should be understood that the terms used in this invention are for the purpose of describing specific embodiments and are not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that any intermediate values ​​between the upper and lower limits of the range are also specifically disclosed. Any value or intermediate value within the stated range, as well as smaller ranges between other stated values ​​or intermediate values ​​within such ranges, are also included in this invention. The upper and lower limits of these smaller ranges may or may not be included in the range.

[0022] Unless otherwise specified, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described in this invention, any methods and materials similar or equivalent to those described in this specification may be used in the implementation or testing of this invention. All documents mentioned in this specification are incorporated by reference to disclose and explain the methods and / or materials related to that document. In case of conflict between the incorporated document and the content of this specification, the content of this specification shall prevail.

[0023] Without departing from the scope or spirit of the present invention, numerous changes and modifications can be made to the specific embodiments of the specification of the present invention, which will be apparent to those skilled in the art. Other embodiments obtained from the specification of the present invention will also be apparent to those skilled in the art. The specification and examples of the present invention are merely illustrative.

[0024] As used in this specification, "comprising", "including", "having", "containing", etc. are all non-limiting expressions, meaning "not limited to these".

[0025] Example 1

[0026] A liquid-phase self-catalytic regenerable absorbent, wherein the mass fraction of the raw materials is as follows: Ethanolamine (MEA) 30%, water 60%, phenol (pKa = 9.97) 10%.

[0027] The process of carbon dioxide absorption and absorbent regeneration is as follows: (1) Carbon dioxide absorption: Dissolve ethanolamine in water, and use the obtained ethanolamine solution to absorb carbon dioxide gas until saturation to obtain an organic amine-rich solution. (2) Regeneration of the absorbent: Phenol is added to the obtained organic amine-rich solution and mixed thoroughly, then heated to 90°C and maintained for 180 minutes to complete the regeneration. After that, it is cooled and allowed to stand, causing the proton transfer agent, phenol, and the organic amine lean solution to separate into phases (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 absorbent.

[0028] The maximum desorption rate of carbon dioxide during the regeneration process reached 3.70 mmol / min.

[0029] Example 2

[0030] The liquid-phase autocatalytic regenerative absorbent has the following mass fractions of raw materials: Ethanolamine (MEA) 30%, water 60%, cresol (pKa=10.20) 10%; here, cresol (CAS: 1319-77-3).

[0031] (1) Absorption of carbon dioxide: Ethanolamine is dissolved in water, and carbon dioxide gas is absorbed using the resulting ethanolamine solution to obtain an organic amine-rich solution. (2) Regeneration of the absorbent: Cresol is added to the obtained organic amine-rich solution and mixed thoroughly. The solution is then heated to 90°C and maintained for 180 minutes to complete the regeneration. After that, it is cooled and allowed to stand, causing the proton transfer agent, cresol, and the organic amine lean solution to separate into phases. This separates 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), thus completing the regeneration of the absorbent.

[0032] The maximum desorption rate of carbon dioxide during the regeneration process reached 5.09 mmol / min.

[0033] Comparative Example 1

[0034] The carbon dioxide absorbent has the following mass fractions of raw materials: Ethanolamine (MEA) 30%, Water 70%.

[0035] Ethanolamine is dissolved in water, and carbon dioxide is absorbed into the resulting ethanolamine aqueous solution until saturated. The resulting organic amine-rich solution is heated to 90°C and maintained for 180 minutes to complete the regeneration process. The maximum desorption rate is 2.13 mmol / min.

[0036] Comparative Example 2

[0037] The carbon dioxide absorbent has the following mass fractions of raw materials: Ethanolamine (MEA) 30%, water 60%, formic acid (pKa=3.57) 10%.

[0038] (1) Absorption of carbon dioxide: Ethanolamine is dissolved in water, and carbon dioxide gas is absorbed using the resulting ethanolamine solution to obtain an organic amine-rich solution. (2) Regeneration of the absorbent: Formic acid is added to the obtained organic amine-rich solution and mixed thoroughly. The solution is then heated to 90°C and maintained for 180 minutes to complete the regeneration. Since formic acid is readily soluble in water, no phase separation is observed after regeneration. However, because the pKa of formic acid is too low, it reacts directly with the absorbent solution, lowering the pKa of the absorbent solution and making it impossible to reuse the absorbent solution. The maximum carbon dioxide desorption rate is 0.50 mmol / min.

[0039] The embodiments described above merely illustrate preferred embodiments of the present invention and do not limit the scope of the invention. Any modifications or improvements made by those skilled in the art to the technical scheme of the present invention, without departing from the spirit of the invention, shall all be included within the scope of protection defined by the claims of the present invention.

Claims

[Claim 1] A method for the autocatalytic regeneration of a carbon dioxide absorbent, The process includes adding a proton transfer agent to an aqueous solution of organic amine that has absorbed carbon dioxide, heating and regenerating the resulting mixture, then allowing it to stand to separate into layers, thereby achieving 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 insoluble with the organic amine, the proton transfer agent is a reagent having a proton transfer activity of 8 < pKa < 16, and the proton transfer agent is a phenol. The heating and regeneration temperature is 70 to 100°C, and the time is 100 to 250 min. A method for autocatalytic regeneration of a carbon dioxide absorbent, characterized in that the mass ratio of the organic amine to the proton transfer agent in the aqueous solution of the organic amine is 20 to 50:0 to 30, and the mass of the proton transfer agent is not 0.