Process for regeneration of a carbon dioxide chemical absorbent and a method for capturing carbon dioxide and apparatus therefor

Abstract

The present application relates to the field of gas separation, in particular to a method for regenerating a carbon dioxide chemical absorbent, a method for capturing carbon dioxide and a device thereof. The method comprises regenerating the chemical absorbent which has absorbed carbon dioxide under the condition of a modified catalyst; the modified catalyst is a heterogeneous catalyst modified by a modifier, and the modifier is selected from at least one of an amine salt type cationic active agent, a quaternary ammonium salt type cationic active agent and a heterocyclic type cationic active agent. The present application realizes the catalytic regeneration of the chemical absorbent at an ultra-low temperature, not only solves the problem of high energy consumption in the regeneration of the existing chemical absorption method technology, significantly reduces the energy consumption of the chemical absorbent regeneration, but also solves the technical bottleneck of high thermal degradation rate and high absorbent loss (low absorbent regeneration rate) of the chemical absorbent, expands the application space of the coupling catalytic regeneration technology of the chemical absorbent and the heterogeneous catalyst, and has important popularization value.

Description

Technical Field

[0001] This invention relates to the field of gas separation, and more specifically to a method for regenerating a carbon dioxide chemical absorbent and a method and apparatus for capturing carbon dioxide. Background Technology

[0002] Since the Industrial Revolution, human consumption of fossil fuels has increased dramatically, leading to higher levels of greenhouse gases in the atmosphere and a significant global warming effect. Among the many greenhouse gases, carbon dioxide (COD) has the greatest impact on global warming, accounting for approximately 55% of the total effect. Therefore, reducing COD emissions is crucial for controlling global warming and has attracted widespread attention from countries around the world. Carbon dioxide capture is one of the important means of COD emission reduction and an important component of energy conservation, emission reduction, and carbon neutrality efforts.

[0003] Carbon dioxide separation technologies mainly include: absorption separation, adsorption separation, membrane separation, and cryogenic separation.

[0004] From the perspective of current technological advancements, absorption is the most mature and widely used carbon dioxide separation technology. Chemical absorption processes, represented by ethanolamine (MEA), are highly mature, capable of recovering high-purity CO2 with relatively low investment costs. They are currently used for both post-combustion and pre-combustion decarbonization.

[0005] The amine process utilizes the chemical reaction between amine molecules and carbon dioxide to separate carbon dioxide from the feed gas. The reaction is then reversed by heating, allowing the carbon dioxide to be separated from the solvent, and the amine solution is regenerated for recycling. Energy consumption is one of the main factors limiting the widespread adoption of amine-based carbon dioxide capture technology. The key to developing advanced amine-based carbon dioxide capture technology lies in reducing process energy consumption.

[0006] In the amine-based carbon dioxide capture technology, the heat required for regeneration is the most significant energy consumption component of the entire process. Currently, there are two main approaches to reducing energy consumption: first, developing novel solvents that utilize steric hindrance or activation effects to reduce the activation energy required for the regeneration reaction, or utilizing phase change effects to reduce the amount of solution needed for regeneration; second, optimizing the heat exchange network through heat coupling to improve the overall energy efficiency of the process. However, heat coupling has its limitations due to pinch point constraints, while novel solvents based on steric hindrance or activation effects are relatively mature, and novel solvents based on phase change effects are still in the pilot-scale research stage. Therefore, further reducing regeneration energy consumption based on existing solvent and heat coupling processes is crucial for the amine-based carbon dioxide capture technology.

[0007] Therefore, it is of great significance to propose a method for energy saving and consumption reduction in a solvent-based carbon dioxide capture and regeneration system. Summary of the Invention

[0008] The purpose of this invention is to overcome the problems of high energy consumption and low absorbent regeneration rate in existing solvent-based carbon dioxide capture regeneration systems, and to provide a method for regenerating carbon dioxide chemical absorbents and a method and apparatus for capturing carbon dioxide, which features low energy consumption and high absorbent regeneration rate.

[0009] To achieve the above objectives, the present invention provides a method for regenerating a carbon dioxide chemical absorbent, the method comprising regenerating the chemical absorbent that has absorbed carbon dioxide under modified catalyst conditions;

[0010] The modified catalyst is a heterogeneous catalyst modified with a modifier selected from at least one of amine salt cationic surfactants, quaternary ammonium salt cationic surfactants, and heterocyclic cationic surfactants.

[0011] A second aspect of the present invention provides a method for capturing carbon dioxide, the method comprising:

[0012] a. Prepare an absorbent solution by dissolving a carbon dioxide chemical absorbent in water;

[0013] b. The carbon dioxide-containing raw material gas is brought into countercurrent contact with the absorbent liquid to obtain a rich absorbent liquid that has absorbed carbon dioxide, and a carbon dioxide-removed gas flow.

[0014] c. The rich absorbent is regenerated to obtain regenerated gas and a lean absorbent that has desorbed carbon dioxide.

[0015] d. The regenerated gas is cooled and separated to obtain carbon dioxide. The lean absorbent liquid, from which carbon dioxide has been removed, is recycled back to step b to absorb carbon dioxide.

[0016] In step c, the carbon dioxide chemical absorbent regeneration method described above is used to regenerate the absorbent solution that has absorbed carbon dioxide.

[0017] A third aspect of the present invention provides an apparatus for capturing carbon dioxide, the apparatus comprising:

[0018] The air intake unit is used to introduce raw gas containing carbon dioxide;

[0019] The absorption unit, which is connected to the outlet of the lower feed unit, is used to make the carbon dioxide-containing raw gas introduced into countercurrent contact with the absorbent liquid from the absorbent liquid inlet of the absorption unit to obtain a rich absorbent liquid that has absorbed carbon dioxide, and a gas flow that has removed carbon dioxide.

[0020] The regeneration unit, which connects the rich absorbent inlet to the rich absorbent outlet of the absorption unit, is used to regenerate the rich absorbent that has absorbed carbon dioxide to obtain regenerated gas and a lean absorbent after carbon dioxide has been removed.

[0021] A cooling unit connected to the regenerated gas inlet and the regenerated gas outlet of the regeneration unit, and a regenerated gas separation unit connected in series with the cooling unit, are used to cool and separate the regenerated gas to obtain carbon dioxide.

[0022] The heat exchange unit is located between the absorption unit and the regeneration unit and is used to exchange heat between the rich absorbent from the absorption unit and the lean absorbent from the regeneration unit.

[0023] The absorption unit is further provided with a reboiler; the regeneration unit is filled with the modified catalyst according to claim 1;

[0024] Optionally, pumping units and / or valves may be installed at the inlet and / or outlet of each unit.

[0025] Through the above technical solution, the present invention has the following beneficial effects:

[0026] This invention achieves ultra-low temperature catalytic regeneration of chemical absorbents by desorbing and regenerating carbon dioxide chemical absorbents in catalysts modified with at least one of amine salt cationic surfactants, quaternary ammonium salt cationic surfactants, and heterocyclic cationic surfactants. This not only solves the problem of high regeneration energy consumption that is common in existing chemical absorption technologies, significantly reducing the energy consumption of chemical absorbent regeneration, but also overcomes the technical bottlenecks of high thermal degradation rate and high absorbent loss (low regeneration rate) of chemical absorbents. It expands the application space of coupled catalytic regeneration technology of chemical absorbents and heterogeneous catalysts and has important promotional value. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a preferred carbon dioxide capture process of the present invention;

[0028] Figure 2 This is a schematic diagram of a preferred regeneration unit of the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1-Fan, 2-Raw gas buffer tank, 3-Absorber, 4-Lean liquid pump, 5-Rich liquid pump, 6-Regeneration tower, 7-Reboiler, 8-Lean and rich liquid heat exchanger, 9-Regeneration gas cooler, 10-Regeneration gas separator. Detailed Implementation

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] In conventional chemical absorption methods, the following reaction equations (1) to (5) illustrate the reaction pathway for the absorption of carbon dioxide in monoethanolamine (MEA) through the formation of carbamates, protonated amines, carbonates, and bicarbonates. In MEA, carbon dioxide is mainly absorbed in the form of carbamates, carbonates, and bicarbonates. Carbon dioxide stripping proceeds in the reverse order of the above reactions. One of the main reasons for the high heat capacity of MEA solvent regeneration is the difficulty in transferring protons from protonated amines to water.

[0033] MEA+CO2←→MEA—COO - +H + (1)

[0034] CO2 + H2O → CO3 -2 +2H + (2)

[0035] CO2 + H2O → HCO3 - +H + (3)

[0036] MEAH + +HCO3 - ←→MEA+H2O+CO2 (4)

[0037] MEAH + +H2O ←→ MEA + H3O + (5)

[0038] The first aspect of the present invention provides a method for regenerating a carbon dioxide chemical absorbent, the method comprising regenerating the chemical absorbent that has absorbed carbon dioxide under modified catalyst conditions;

[0039] The modified catalyst is a heterogeneous catalyst modified with a modifier selected from at least one of amine salt cationic surfactants, quaternary ammonium salt cationic surfactants, and heterocyclic cationic surfactants.

[0040] This invention achieves ultra-low temperature catalytic regeneration of chemical absorbents by desorbing and regenerating carbon dioxide chemical absorbents in catalysts modified with at least one of amine salt cationic surfactants, quaternary ammonium salt cationic surfactants, and heterocyclic cationic surfactants. This not only solves the problem of high regeneration energy consumption that is common in existing chemical absorption technologies and significantly reduces the energy consumption of chemical absorbent regeneration, but also solves the technical bottlenecks of high thermal degradation rate and high absorbent loss (low regeneration rate) of chemical absorbents.

[0041] This invention utilizes a modified catalyst capable of attaching the amine—COO- to a proton (H) on the N atom of the urethane form of the amine absorbent. Electron pairs are accepted at Lewis acid sites on the catalyst, where Brønsted acid sites are protonated on the N atom of the urethane. Finally, as the NC bond weakens, carbon dioxide is regenerated in the absorbent at a lower temperature.

[0042] In the method provided by this invention, the modified catalyst modifies the surface properties of a conventional catalyst through a desilication and recombination process. The modified catalyst participates in the proton exchange reaction, accelerating carbon dioxide stripping. This catalyst can combine with carbamates, carbonates, and bicarbonates present in solution to desorb carbon dioxide from the absorbent via a low activation energy pathway.

[0043] According to a preferred embodiment of the present invention, the modified catalyst further includes a modifying agent, which includes sodium hydroxide and / or magnesium hydroxide. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0044] According to a preferred embodiment of the present invention, the modifier is a composition of a quaternary ammonium salt cationic surfactant and an amine salt cationic surfactant; or a composition of a quaternary ammonium salt cationic surfactant and a heterocyclic cationic surfactant. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0045] In this invention, to achieve the objectives of the invention, there are no particular requirements regarding the mass ratio of the quaternary ammonium salt cationic surfactant to the amine salt cationic surfactant in the composition of the quaternary ammonium salt cationic surfactant and the amine salt cationic surfactant. According to a preferred embodiment of the invention, the mass ratio of the quaternary ammonium salt cationic surfactant to the amine salt cationic surfactant in the composition of the quaternary ammonium salt cationic surfactant and the amine salt cationic surfactant is 8–12:1. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0046] In this invention, to achieve the objectives of the invention, there are no particular requirements regarding the mass ratio of the quaternary ammonium salt cationic surfactant to the heterocyclic cationic surfactant in the composition of the quaternary ammonium salt cationic surfactant and the heterocyclic cationic surfactant. According to a preferred embodiment of the invention, the mass ratio of the quaternary ammonium salt cationic surfactant to the heterocyclic cationic surfactant in the composition of the quaternary ammonium salt cationic surfactant and the heterocyclic cationic surfactant is 8–12:1. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0047] In this invention, the amine salt-type cationic surfactant can be a conventional choice in the art. According to a preferred embodiment of the invention, the amine salt-type cationic surfactant includes C6-C22 long-chain alkyl fatty amine salts and / or alcoholic amine salts, preferably including ethanolamine salts and polyvinyl polyamine salts, more preferably including ethanolamine phosphate and polyvinyl polyamine salts. By adopting the aforementioned preferred scheme, the energy consumption, degradation rate, and loss of the chemical absorbent can be further reduced, and the absorbent regeneration rate can be improved.

[0048] In this invention, the quaternary ammonium salt cationic surfactant can be a conventional choice in the art. According to a preferred embodiment of this invention, the quaternary ammonium salt cationic surfactant is selected from those containing C... 10 ~C 18 The long-chain alkyl cationic surfactant preferably includes at least one of dodecyl dimethyl benzyl ammonium chloride, hexadecyl trimethyl ammonium bromide, octadecyl dimethyl benzyl ammonium chloride, and octadecyl methyl dihydroxyethyl ammonium bromide. By adopting the aforementioned preferred scheme, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0049] In this invention, the heterocyclic cationic surfactant can be a conventional choice in the art. According to a preferred embodiment of the invention, the heterocyclic cationic surfactant is selected from at least one of imidazoline, morpholine, and guanidine derivatives, preferably at least one of imidazoline, morpholine, and guanidine. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0050] In this invention, the type of heterogeneous catalyst is not limited as long as the purpose of this invention can be achieved. According to a preferred embodiment of this invention, the heterogeneous catalyst is a solid acid catalyst, selected from at least one of metal catalysts, metal oxide catalysts, complex catalysts, molecular sieve catalysts, solid superacids, and nanocatalysts.

[0051] According to a preferred embodiment of the present invention, the heterogeneous catalyst is selected from at least one of molecular sieve catalysts, metal catalysts, metal oxide catalysts, and solid superacids, preferably a mixed catalyst of a metal oxide catalyst and a solid superacid. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0052] In this invention, the metal catalyst can be a conventional choice in the art.

[0053] In this invention, the metal oxide catalyst can be a conventional choice in the art. According to a preferred embodiment of the invention, the metal oxide catalyst is alumina.

[0054] In this invention, the molecular sieve catalyst can be a conventional choice in the art.

[0055] In this invention, the solid superacid can be a conventional choice in the art. According to a preferred embodiment of this invention, the solid superacid is SO4. 2- / Al2O3-Al.

[0056] The method for modifying the catalyst according to the present invention includes: modifying the surface properties of a conventional catalyst, wherein the modification is carried out by a modified desilication and recombination method, and the recombination process includes desilication reaction and ion exchange reaction steps.

[0057] According to a preferred embodiment of the present invention, the chemical absorbent comprises an organic amine compound. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0058] According to a preferred embodiment of the present invention, the chemical absorbent is a composite absorbent composed of an organic amine compound and a non-aqueous solvent, wherein the non-aqueous solvent is selected from amino acids and / or sterically hindered amines. By adopting the aforementioned preferred embodiment, the energy consumption for chemical absorbent regeneration, as well as the degradation rate and loss, can be further reduced, thereby improving the absorbent regeneration rate.

[0059] In this invention, the amino acid can be a conventional choice in the art. According to this invention, the amino acid is selected from one or more of alanine, glutamic acid, serine, sarcosine, glycine, and lysine.

[0060] In this invention, the sterically hindered amine can be a conventional choice in the art. According to this invention, the sterically hindered amine is selected from 2-amino-2-methyl-1-propanol (AMP) and / or tert-butylaminoethoxyethanol (TBEE).

[0061] In this invention, the organic amine compound can be any conventional choice in the art, as long as it achieves the objective of the invention. According to a preferred embodiment of the invention, the organic amine compound is selected from at least one of monoethanolamine, diethanolamine, triethanolamine, tetraethylenepentanediamine, triethylenetetramine, N-methylmonoethanolamine, N-methyldiethanolamine, caprolactam, 2-amino-2-methyl-1-propanol, diisopropanolamine, diazabicyclo, hydroxyethylpiperazine, and morpholine. By adopting the aforementioned preferred embodiment, the energy consumption, degradation rate, and loss of the chemical absorbent regeneration can be further reduced, and the absorbent regeneration rate can be improved.

[0062] In this invention, the conditions for absorbent regeneration can be conventionally selected in the art. According to a preferred embodiment of this invention, the conditions for absorbent regeneration include: a regeneration temperature of 45–65°C and a regeneration pressure of 0–80 kPa, preferably 10–50 kPa.

[0063] A second aspect of the present invention provides a method for capturing carbon dioxide, the method comprising:

[0064] a. Prepare an absorbent solution by dissolving a carbon dioxide chemical absorbent in water;

[0065] b. The carbon dioxide-containing raw material gas is brought into countercurrent contact with the absorbent liquid to obtain a rich absorbent liquid that has absorbed carbon dioxide, and a carbon dioxide-removed gas flow.

[0066] c. The rich absorbent is regenerated to obtain regenerated gas and a lean absorbent that has desorbed carbon dioxide.

[0067] d. The regenerated gas is cooled and separated to obtain carbon dioxide. The lean absorbent liquid that has desorbed carbon dioxide is recycled back to step b to absorb carbon dioxide.

[0068] In step c, the carbon dioxide chemical absorbent regeneration method provided in the first aspect is used to regenerate the absorbent rich solution that has absorbed carbon dioxide.

[0069] According to a preferred embodiment of the present invention, the molar concentration of the absorbent in step a is 1 to 5 mol / L.

[0070] According to a preferred embodiment of the present invention, the contact conditions in step b include: a temperature of 30 to 40°C and a pressure of 2 to 10 kPa.

[0071] A third aspect of the present invention provides an apparatus for capturing carbon dioxide, the apparatus comprising:

[0072] The air intake unit is used to introduce raw gas containing carbon dioxide;

[0073] The absorption unit, which is connected to the outlet of the lower feed unit and the air inlet unit, is used to make the carbon dioxide-containing raw material gas introduced into countercurrent contact with the absorbent liquid from the absorbent liquid inlet of the absorption unit to obtain a rich absorbent liquid that has absorbed carbon dioxide, and a carbon dioxide-removed gas flow.

[0074] The regeneration unit, which connects the rich absorbent inlet to the rich absorbent outlet of the absorption unit, is used to regenerate the rich absorbent that has absorbed carbon dioxide to obtain regenerated gas and a lean absorbent that has desorbed carbon dioxide.

[0075] A cooling unit connected to the regenerated gas inlet and the regenerated gas outlet of the regeneration unit, and a regenerated gas separation unit connected in series with the cooling unit, are used to cool and separate the regenerated gas to obtain carbon dioxide.

[0076] The heat exchange unit is located between the absorption unit and the regeneration unit and is used to exchange heat between the rich absorbent from the absorption unit and the lean absorbent from the regeneration unit.

[0077] The absorption unit is also equipped with a reboiler, and the regeneration unit is filled with the modified catalyst.

[0078] According to a preferred embodiment of the present invention, a pumping unit and / or a valve are provided at the inlet and / or outlet of each unit.

[0079] The device of this invention only requires heating in the regeneration unit to achieve ultra-low temperature gas stripping catalytic coupling regeneration of the absorbent, significantly reducing the energy consumption for absorbent regeneration. It achieves low-temperature regeneration, allowing the lean liquid to directly enter the absorption unit after recovering some heat via a lean-rich liquid heat exchanger, eliminating the need for a lean liquid cooler, saving equipment investment, and simplifying the process. The significantly reduced regeneration temperature avoids the thermal degradation caused by high-temperature regeneration, which is unavoidable in traditional chemical absorption methods. This simultaneously reduces absorbent degradation losses, improves absorbent stability, reduces degradation products, increases absorbent regeneration rate, and achieves green regeneration of the absorbent.

[0080] like Figure 1In the CO2 capture process provided by this invention, the raw gas is sent from the blower 1 through the raw gas buffer tank 2 into the absorption tower 3. The CO2 in the raw gas is absorbed by the absorbent. The rich liquid after CO2 absorption flows from the bottom of the absorption tower through the rich liquid pump 5 and the lean-rich liquid heat exchanger 8 to recover heat before entering the regeneration tower 6. After entering the regeneration tower, the rich liquid undergoes gas stripping and catalytic regeneration in the reboiler 7 to desorb CO2 and water vapor from the solution. It is then cooled by the regeneration gas cooler 9 and separated by the regeneration gas separator 10 to remove moisture, yielding regeneration gas CO2 (product gas). The rich liquid after CO2 absorption enters the regeneration tower for regeneration. The regenerated lean liquid comes out from the bottom of the regeneration tower, passes through the lean-rich liquid heat exchanger, and is directly sent to the absorption tower by the lean liquid pump 4. The solution circulates back and forth, constituting a continuous process of CO2 absorption and regeneration. The purity of the regenerated CO2 reaches 99.5%.

[0081] In this invention, the absorption tower is a conventional absorption tower.

[0082] In this invention, the regeneration tower is a catalytic regeneration tower. The modified catalyst is packed in the regeneration tower and fixed in the packing layer of the regeneration tower. It is combined with the packing of the regeneration tower by direct processing and / or placed in the bottom of the regeneration tower by coating.

[0083] The present invention will be described in detail below through embodiments. In the following embodiments, the parameters were measured by conventional methods in the art, and the raw materials were all commercially available products.

[0084] The method in the following embodiments is implemented according to the following steps:

[0085] Use attached Figure 1 The device was used for a performance evaluation test of catalytic regeneration of CO2-capturing alcoholamine solvent. The feed gas was pressurized and fed into the system by a blower, passing through a feed gas buffer tank before entering the absorption tower. CO2 in the feed gas was absorbed counter-currently by the absorbent in the absorption tower. The CO2-rich amine solution, after CO2 absorption, underwent a lean-rich liquid heat exchange and then entered the regeneration tower. Through gas stripping and modified catalytic regeneration, CO2 was desorbed from the absorbent. After cooling by a regeneration gas cooler, the product gas CO2 was separated by a regeneration gas separator and sent to the subsequent process. The regenerated absorbent, after passing through a lean-rich liquid heat exchanger, was sent back to the absorption tower to recycle and absorb CO2. This cycle repeats continuously, constituting a continuous CO2 absorption and regeneration process.

[0086] Comparative Example 1

[0087] The feed gas is a simulated desulfurization tail gas from a boiler in a chemical plant. By volume, it contains 12% CO2, 8% O2, 77% N2, and 3% H2O, with a flue gas volume of 3.0 Nm³. 3 / h. The absorbent is monoethanolamine (MEA), prepared as an aqueous solution with a molar concentration of 3.3 mol / L. The absorption and regeneration towers are conventional packed towers; the regeneration tower does not contain a catalyst. The absorption temperature is 40℃, the absorption pressure is 5 kPa, the regeneration temperature is 50℃, and the regeneration pressure is 25 kPa. Saturated CO2 absorption is performed first, followed by an evaluation of the absorbent's regeneration performance.

[0088] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 41.25 L / L, the acid gas content in the rich solution was 41.32 L / L, the CO2 content in the regeneration gas was 0, and there was no regeneration.

[0089] Comparative Example 2

[0090] The feed gas is a simulated desulfurization tail gas from a boiler in a chemical plant. By volume, it contains 12% CO2, 8% O2, 77% N2, and 3% H2O, with a flue gas volume of 3.0 Nm³. 3 / h. The absorbent is monoethanolamine (MEA), prepared as an aqueous solution with a molar concentration of 3.3 mol / L. The absorption tower is a conventional packed tower, and the packing layer of the regeneration tower is equipped with a γ-Al₂O₃ catalyst. The absorption temperature is 40℃, the absorption pressure is 5 kPa, the regeneration temperature is 50℃, and the regeneration pressure is 25 kPa. Saturated CO₂ absorption is performed first, followed by evaluation of the absorbent's regeneration performance.

[0091] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 41.16 L / L, and the acid gas content in the rich solution was 41.38 L / L. The CO2 content in the regenerated gas was 0.

[0092] Example 1

[0093] The feed gas is a simulated desulfurization tail gas from a boiler in a chemical plant. By volume, it contains 12% CO2, 8% O2, 77% N2, and 3% H2O, with a flue gas volume of 3.0 Nm³. 3 / h. The absorbent is monoethanolamine (MEA), prepared as an aqueous solution with a molar concentration of 3.3 mol / L. The absorption tower is a conventional packed tower, and the regeneration tower packing layer is equipped with a modified catalyst, which is a solid superacid catalyst SO4. 2- / Al2O3-Al, with the addition of cationic surfactant hexadecyltrimethylammonium bromide (CTAB) and modifier magnesium hydroxide Mg(OH)2. Absorption temperature 40℃, absorption pressure 5kPa, regeneration temperature 50℃, regeneration pressure 25kPa. CO2 saturation absorption was performed first, followed by evaluation of the absorbent's regeneration performance.

[0094] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 21.36 L / L, and the acid gas content in the rich solution was 43.82 L / L. The CO2 content in the regeneration gas was 85.6%, and the absorbent regeneration rate was 53.3%.

[0095] Example 2

[0096] Same as Example 1, except that: the absorbent is N-methyldiethanolamine, prepared as an aqueous solution with a molar concentration of 5 mol / L, and the packing layer of the regeneration tower is equipped with a packing-type modified catalyst, wherein the modified catalyst is a metal oxide catalyst γ-Al2O3, with the addition of cationic activator polyethylene polyamine salt and modifying agent sodium hydroxide. The absorption temperature is 30°C, the absorption pressure is 10 kPa, the regeneration temperature is 65°C, and the regeneration pressure is 10 kPa. CO2 saturation absorption is performed first, and then the regeneration performance of the absorbent is evaluated.

[0097] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 22.65 L / L, the acid gas content in the rich solution was 43.38 L / L, the CO2 content in the regeneration gas was 85.7%, and the absorbent regeneration rate was 54.2%.

[0098] Example 3

[0099] Same as Example 1, except that: the absorbent is hydroxyethylpiperazine, prepared as an aqueous solution with a molar concentration of 1 mol / L; and the packing layer of the regeneration tower is equipped with a modified catalyst, which is a solid superacid catalyst SO4. 2- / Al2O3-Al, with the addition of cationic surfactant morpholine and modifier magnesium hydroxide, absorption temperature 35℃, absorption pressure 2kPa, regeneration temperature 45℃, and regeneration pressure 50kPa, first perform CO2 saturation absorption, and then evaluate the regeneration performance of the absorbent.

[0100] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 20.16 L / L, and the acid gas content in the rich solution was 44.32 L / L. The CO2 content in the regeneration gas was 86.5%, and the absorbent regeneration rate was 58.7%.

[0101] Example 4

[0102] Similar to Example 1, except that: the absorbent is a composite absorbent composed of monoethanolamine and 2-amino-2-methyl-1-propanol (AMP) in a weight ratio of 5:1, prepared as an aqueous solution with a molar concentration of 3.3 mol / L, and an equal amount of a composite cationic surfactant composed of hexadecyltrimethylammonium bromide and morpholine in a mass ratio of 10:1 is added, along with an equal amount of modifying agent (a mixture of magnesium hydroxide and sodium hydroxide in a mass ratio of 1:1). CO2 saturation absorption is performed first, and then the regeneration performance of the absorbent is evaluated.

[0103] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 12.27 L / L, and the acid gas content in the rich solution was 45.39 L / L. The CO2 content in the regeneration gas was 99.6%, and the absorbent regeneration rate was 73.0%.

[0104] Example 5

[0105] Same as Example 1, except that magnesium hydroxide is not added.

[0106] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 23.25 L / L, the acid gas content in the rich solution was 41.12 L / L, the CO2 content in the regeneration gas was 78.5%, and the absorbent regeneration rate was 50.3%.

[0107] Example 6

[0108] Same as Example 4, except that the modifier is a mixed modifier of octadecylmethyldihydroxyethylammonium bromide and ethanolamine phosphate in a mass ratio of 8:1.

[0109] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 13.27 L / L, and the acid gas content in the rich solution was 45.05 L / L. The CO2 content in the regeneration gas was 99.5%, and the absorbent regeneration rate was 72.2%.

[0110] Example 7

[0111] Same as Example 6, except that the modifier is octadecylmethyldihydroxyethylammonium bromide and ethanolamine phosphate in a mass ratio of 5:1.

[0112] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 18.51 L / L, and the acid gas content in the rich solution was 44.85 L / L. The CO2 content in the regeneration gas was 90.2%, and the absorbent regeneration rate was 65.1%.

[0113] Example 8

[0114] Same as Example 1, except that the absorbent is a composite absorbent composed of monoethanolamine and sterically hindered amine 2-amino-2-methyl-1-propanol (AMP) in a weight ratio of 5:1.

[0115] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 19.72 L / L, and the acid gas content in the rich solution was 44.12 L / L. The CO2 content in the regeneration gas was 89.6%, and the absorbent regeneration rate was 64.2%.

[0116] Example 9

[0117] Same as Example 1, except that the catalyst is γ-Al2O3 and SO4 in a weight ratio of 1:3. 2- / Al2O3-Al.

[0118] Experimental results: After absorption saturation, continuous regeneration test for 2 hours showed that the acid gas content in the lean solution was 17.33 L / L, and the acid gas content in the rich solution was 44.54 L / L. The CO2 content in the regeneration gas was 91.6%, and the absorbent regeneration rate was 66.5%.

[0119] The results show that the technical solution of the present invention can significantly reduce the regeneration energy consumption of the absorbent (achieving low-temperature regeneration) and improve the regeneration rate of the absorbent.

[0120] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for regenerating a carbon dioxide chemical absorbent, characterized in that, The method includes regenerating the chemical absorbent that has absorbed carbon dioxide under modified catalyst conditions; The modified catalyst is a heterogeneous catalyst modified by a modifier, and the heterogeneous catalyst is a mixed catalyst of metal oxide catalyst and solid superacid; The modifier is a combination of a quaternary ammonium salt cationic surfactant and an amine salt cationic surfactant; or a combination of a quaternary ammonium salt cationic surfactant and a heterocyclic cationic surfactant. In the composition of quaternary ammonium salt cationic surfactant and amine salt cationic surfactant, the mass ratio of quaternary ammonium salt cationic surfactant to amine salt cationic surfactant is 8~12:1; In the composition of quaternary ammonium salt cationic surfactant and heterocyclic cationic surfactant, the mass ratio of quaternary ammonium salt cationic surfactant to heterocyclic cationic surfactant is 8~12:1; The modified catalyst further includes modifying agents, including sodium hydroxide and magnesium hydroxide; The amine salt type cationic surfactants include ethanolamine salts and polyvinyl polyamine salts; The quaternary ammonium salt cationic surfactant includes at least one of dodecyl dimethyl benzyl ammonium chloride, hexadecyl trimethyl ammonium bromide, octadecyl dimethyl benzyl ammonium chloride, and octadecyl methyl dihydroxyethyl ammonium bromide; The heterocyclic cationic surfactant is selected from at least one of imidazoline, morpholine, and guanidine.

2. The method according to claim 1, wherein, The chemical absorbent contains organic amine compounds.

3. The method according to claim 2, wherein, The absorbent is a composite absorbent composed of organic amine compounds and non-aqueous solvents, wherein the non-aqueous solvents are selected from amino acids and / or sterically hindered amines.

4. The method according to claim 3, wherein, The amino acid is selected from one or more of alanine, glutamic acid, serine, sarcosine, glycine, and lysine; and / or The sterically hindered amine is selected from one or more of 2-amino-2-methyl-1-propanol (AMP) and tert-butylaminoethoxyethanol (TBEE).

5. The method according to claim 3, wherein, The organic amine compound is selected from at least one of monoethanolamine, diethanolamine, triethanolamine, tetraethylenepentanediamine, triethylenetetramine, N-methylmonoethanolamine, N-methyldiethanolamine, caprolactam, 2-amino-2-methyl-1-propanol, diisopropanolamine, diazabicyclo, hydroxyethylpiperazine, and morpholine.

6. The method according to claim 1, wherein, The conditions for regenerating the absorbent include: a regeneration temperature of 45~65℃ and a regeneration pressure of 0~80kPa.

7. The method according to claim 6, wherein, The regeneration pressure is 10~50 kPa.

8. A method for capturing carbon dioxide, characterized in that, The method includes: a. Prepare an absorbent solution by dissolving a carbon dioxide chemical absorbent in water; b. The carbon dioxide-containing raw material gas is brought into countercurrent contact with the absorbent liquid to obtain a rich absorbent liquid that has absorbed carbon dioxide, and a carbon dioxide-removed gas flow. c. The rich absorbent is regenerated to obtain regenerated gas and a lean absorbent that has desorbed carbon dioxide. d. The regenerated gas is cooled and separated to obtain carbon dioxide. The lean absorbent liquid that has desorbed carbon dioxide is recycled back to step b to absorb carbon dioxide. In step c, the absorbent rich solution that has absorbed carbon dioxide is regenerated using the method described in any one of claims 1-7.

9. The method according to claim 8, wherein, The molar concentration of the absorbent in step a is 1~5 mol / L; The contact conditions described in step b include: a temperature of 30~40℃ and a pressure of 2~10kPa.

10. An apparatus employing the carbon dioxide capture method according to claim 8 or 9, characterized in that, The device includes: The air intake unit is used to introduce raw gas containing carbon dioxide; The absorption unit, which is connected to the outlet of the lower feed unit, is used to make the carbon dioxide-containing raw gas introduced into countercurrent contact with the absorbent liquid from the absorbent liquid inlet of the absorption unit to obtain a rich absorbent liquid that has absorbed carbon dioxide, and a gas flow that has removed carbon dioxide. The regeneration unit, which connects the rich absorbent inlet to the rich absorbent outlet of the absorption unit, is used to regenerate the rich absorbent that has absorbed carbon dioxide to obtain regenerated gas and a lean absorbent that has desorbed carbon dioxide. A cooling unit connected to the regenerated gas inlet and the regenerated gas outlet of the regeneration unit, and a regenerated gas separation unit connected in series with the cooling unit, are used to cool and separate the regenerated gas to obtain carbon dioxide. The heat exchange unit is located between the absorption unit and the regeneration unit and is used to exchange heat between the rich absorbent from the absorption unit and the lean absorbent from the regeneration unit. The absorption unit is further provided with a reboiler; the regeneration unit is filled with the modified catalyst according to claim 1; Optionally, pumping units and / or valves may be installed at the inlet and / or outlet of each unit.

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