Carbon dioxide absorbing liquid, its preparation method and application

Abstract

The application discloses a kind of carbon dioxide absorption liquid and its preparation method and application, it is related to gas purification technical field, by weight percentage, including 15wt%~40wt% amine compound, 0.5wt%~5wt% weak acid compound and / or ester compound, 0.5wt%~2wt% antioxidant, the balance is water;Antioxidant is the mixture of iodized metal and amino acid.The antioxidant in the absorption liquid utilizes the non-consumption and stable characteristics of iodized metal, from the source inhibits the possibility of amine molecule oxidant degradation, supplemented with amino acid compatibility to enhance the anti-oxidation effect of absorption liquid at high temperature, and guarantee its removal capacity, with weak acid compound or ester compound, on the one hand, further reduce the corrosive nature of decarburization solution, on the other hand, can have certain regeneration energy-saving effect, therefore the carbon dioxide absorption liquid in the application has good technical economy.

Description

Technical Field

[0001] This invention relates to the field of gas purification technology, specifically to a carbon dioxide absorbent liquid, its preparation method, and its application. Background Technology

[0002] With increasing global concern about global warming, environmental regulations are becoming increasingly stringent worldwide, making the reduction of emissions from the petrochemical industry an urgent issue. Humanity will rely on fossil fuels for a long time to come, and carbon capture, as a crucial technology for reducing emissions, is a key industrial method. Large-scale industrial carbon capture primarily utilizes chemical amine absorbents to recover CO2. This involves amines with amino groups reacting with CO2 under low pressure, releasing the CO2 at high temperatures for reduction and recycling. However, petrochemical emissions typically contain oxygen, nitrogen oxides, and sulfur dioxide in addition to carbon dioxide. These components degrade the chemical amine solvents, causing solution deactivation, decreased alkalinity, and reduced carbon dioxide absorption capacity. Furthermore, the generated heat-stable salts and degradation products corrode the carbon steel used in decarbonization equipment.

[0003] To address these issues, existing technologies typically require the addition of antioxidants and slow-release agents to amine absorbents to ensure solvent activity and reduce solution loss. Corrosion inhibitors used include metal oxides, weak acid salts, and imidazoline compounds, while antioxidants mainly include phenols and enamines. However, all of these are consumed, their effects are not sustained, or they negatively impact solution performance (e.g., increased viscosity, increased byproducts, affecting mass transfer).

[0004] For chemical amine solution decarbonization systems, solution degradation or deterioration mainly occurs in two ways. One is through amine oxidation, where carbon-nitrogen bonds break to form organic acids such as formic acid, acetic acid, and oxalic acid. These react with amine molecules to form weak acid amine salts, which are often called heat-stable salts due to their difficulty in regeneration. The other way is through amine decarbonization under heat or impurities (SO2, NO). X Under certain conditions, amines undergo thermal decomposition or oxidative degradation, generating a series of complex organic compounds such as formamide, ethylene glycol, 1,4-dimethylpiperazine, and 3-(hydroxyethyl)-2-oxazolidinone. This leads to the loss of effective amines and a decline in solution performance. Therefore, oxidative degradation is the primary cause of deterioration and corrosion. Thermal degradation, influenced by factors such as operating pressure and regeneration quality, should not be ignored. In particular, heat-stable salts continuously combine with metal ions, thinning their surface and causing corrosion problems in the equipment. Amines themselves are not corrosive; the root cause of their corrosion is the reaction between degradation intermediates or products during use and the metal, resulting in a vicious cycle where both react and promote each other.

[0005] In existing technologies, adding antioxidants to amine absorbents effectively inhibits the oxidative decomposition of amine organic compounds or the reaction process of oxidation intermediates, thereby improving the stability of the solvent performance in the decarbonization process. Taking sulfite as an example, sodium sulfite provides sulfite ions (SO32-). 2- Phenolic antioxidants react with oxygen in solution to form sulfates, thus indirectly preventing the oxidation of amines. However, they are consumed and need to be replenished periodically in practical use. Phenolic antioxidants can disrupt the chain reaction of oxygen free radicals during amine oxidation. However, in this step, phenolic antioxidants are converted into other relatively stable free radicals and no longer have the ability to further capture oxygen free radicals. They also have the problem of needing to be replenished when they become ineffective.

[0006] In existing technologies, the role of adding corrosion inhibitors to amine absorbents is to form a film on the internal surface of equipment and pipelines, preventing metal ions from continuously detaching from the equipment substrate and inhibiting further degradation and deterioration of the amine by the catalytic oxidation of metal ions. When the metal surface is covered with a weak acid metal salt, the acid anions are adsorbed on the metal surface, preventing direct contact between the base metal and the acidic medium in the solution. This physical barrier further slows down the corrosion rate. Since flue gas is at normal pressure, under these conditions, it is difficult to form a dense crystalline protective layer on the metal surface due to the low pressure; it usually thins or falls off with the flow of the solution. Taking trisodium phosphate as an example, its corrosion inhibition efficiency is 91-94% in the concentration range of 250-10000 ppm. However, due to the instability of its passivation film, it is only effective in the short term and needs to be added periodically in actual use. Metal oxides, such as vanadium pentoxide, form a dense and stable oxide film, thus blocking further corrosion. Furthermore, metal oxides can also react in amine solutions to form salts, equivalent to the corrosion inhibition effect of the aforementioned weak acid salts. These were initially used for passivation pre-filming of carbon steel equipment, but are now rarely used due to the harmful effects of heavy metals on human health. Potassium sodium tartrate and ethylenediaminetetraacetic acid (EDTA), as metal chelating agents or shielding agents, inhibit the reaction between amines and metals by forming chelates with metal ions. This prevents metal ions from being exposed to an oxygen atmosphere, thus avoiding subsequent oxidative degradation. However, if the amine continues to degrade and deteriorate, the metal ions in the equipment matrix will continuously be bound and released. Therefore, these metal chelating agents only provide a temporary solution. Summary of the Invention

[0007] Given the problems of current carbon dioxide absorbent solutions such as consumption, inconsistent effectiveness, or negative impacts on solution performance, the purpose of this invention is to provide a carbon dioxide absorbent solution, its preparation method, and its application. This solution can effectively inhibit the degradation and corrosion of carbon capture solvents, and the consumption of antioxidants and corrosion inhibitors in the absorbent solution is minimal, without negatively impacting solution performance, and the effect is sustainable.

[0008] This invention is achieved through the following technical solution:

[0009] In a first aspect, the present invention provides a carbon dioxide absorbent, comprising, by weight percentage, 15wt% to 40wt% of an amine compound, 0.5wt% to 5wt% of a weak acid compound and / or an ester compound, 0.5wt% to 2wt% of an antioxidant, and the balance being water;

[0010] The antioxidant is a mixture of metal iodide and amino acids.

[0011] The antioxidant in this invention utilizes the non-consumption and stability of metal iodides to inhibit the degradation of amine molecules by oxidants at the source. It is supplemented with amino acids to enhance the absorbent's resistance to high-temperature oxidation and ensure its removal capacity. Since the decarbonization solution cannot be completely regenerated, meaning the corrosive effect of carbamates always exists, weak acid compounds or ester compounds are used in conjunction. This further reduces the corrosivity of the decarbonization solution and provides a certain degree of regeneration and energy-saving effect. Therefore, the carbon dioxide absorbent in this invention has good technical and economic efficiency.

[0012] Among them, iodide ions in metal iodides act as highly efficient free radical scavengers, interrupting the degradation reaction through the following pathways:

[0013] Destroying free radicals: I - +·OH→I·+OH - (Fast reaction, rate constant ~10) 10 The generated iodine free radicals (I·) have low activity and are unlikely to initiate further chain reactions.

[0014] Chain termination effect: I- can terminate the growth of free radical chains, for example: ROO·+I - →ROO - +I·ROO·+I - →ROO - +I·.

[0015] The generated I· dimerizes to form stable I2, which can then be reduced back to I in a reducing amine solution. - This forms a cycle.

[0016] Iodide ions in iodides can act as antioxidants, scavenging free radicals and thus slowing down the oxidation process of amine molecules. Alternatively, they can react with degradation intermediates through catalytic mechanisms, preventing the continuation of chain reactions. For example, in free radical chain reactions, iodide ions can act as chain terminators, combining with free radicals to form stable substances, thereby interrupting the degradation reaction. In this case, the metal iodide is not consumed, as it only participates in the reaction as a catalyst or stabilizer but is ultimately regenerated. The degradation of amine molecules is related to metal catalysis; for example, iron and copper ions catalyze oxidation reactions. Metal iodides can reduce the catalytic activity of these metal ions by complexing them, thus slowing down degradation. Furthermore, metal iodides are neutral salts, having little effect on pH and not affecting solution properties. In oxidation reactions, I... - It is oxidized to I₂, but then reduced back, forming a cycle, so the overall concentration remains constant. In this case, the metal iodide actually participates in the reaction, but the total amount remains constant through the redox cycle.

[0017] In this invention, the carbon dioxide absorption reaction of the amine compounds is carried out as an equilibrium reaction of the following two reactions: one reaction is the reaction of the nitrogen of the amino group with the carbon of carbon dioxide to form carbamic acid, and the other reaction is the reaction of water molecules via bicarbonate. For primary and secondary amines, carbamic acid is formed first, and then bicarbonate is formed. Since carbamic acid is unstable in water, it will further react with another molecule of amine compound to form carbamate or hydrolyze to form bicarbonate. Depending on the basicity of the amine compound, the bicarbonate further becomes carbonate.

[0018] The purpose of adding weak acid compounds in this invention is to react with amine molecules in amine compounds to form weak acid amine salts, creating a buffer system to ensure that the absorption effect is not affected. Esters themselves are not acidic or basic; in the alkaline environment of the amine solution, hydrolysis completely produces weak acid amine salts and alcohols. The formed weak acid amine salts, together with the weak acid amine salts formed by the weak acid compounds and amine compounds, maintain the stability of the buffer system. Within this buffer system, the pH value of the solution can be stabilized within a certain range, ensuring both the removal capacity and reactivity of the absorbent. Furthermore, the alcohols formed from the hydrolysis of ester compounds can act as non-aqueous solvents with low specific heat, further reducing the sensible heat of the absorbent when heated. For solid amines, such as piperazine and pyridine, the solubility in water is limited, restricting their concentration. The alcohols formed from the hydrolysis of esters can significantly improve their solubility. Therefore, weak acid compounds and ester compounds can be selected based on the type of amine compound.

[0019] Furthermore, the amine compound contains an amino group, a carboxyl group, and / or an alkyl group in its molecule.

[0020] Furthermore, the amine compounds include alkyl alcoholamines or alkylamines.

[0021] Furthermore, the alkyl alcoholamine includes any one or more combinations of ethanolamine, diethylene glycolamine, diethanolamine, methyldiethanolamine, hydroxyethylenediamine, 2-amino-2-methyl-1-propanol, and 2-piperidineethanol.

[0022] Furthermore, the alkylamine includes any one or more combinations of diethylenetriamine, 1,6-ethylenediamine, piperazine, aminoethylpiperazine, and 2-methylpiperazine.

[0023] Furthermore, the weak acid compound includes boric acid, phosphoric acid, or glacial acetic acid.

[0024] Because amine borate and amine phosphate are weaker acids than amine carbamate or amine carbonate, their neutralization reaction with amine compounds is insufficient, leading to more bicarbonate formation than carbonate formation. This reduces the heat of reaction and consequently the energy required for absorbent regeneration (CO2 desorption). Simultaneously, the alkalinity of the absorbent decreases, reducing its corrosiveness to metals. However, adding strong acids, such as sulfuric acid or hydrochloric acid, will directly react to form heat-stable amine salts, causing some amine compounds to deactivate. Therefore, a stronger acid than bicarbonate ions is necessary. Weak acid amine salts are similar to amino acids, belonging to amphoteric compounds, and are cheaper than amino acids, making them more practical. Their acid strength pKa is temperature-dependent, being stronger at higher temperatures than at lower temperatures. Since absorbent regeneration typically occurs at higher temperatures than CO2 absorption, the absorbed CO2 is more easily released, reducing the energy required for regeneration. At lower temperatures, they are neutral or only slightly acidic, therefore their absorption capacity is unaffected or only slightly affected. Because the regeneration quality of the lean solution improves, the corrosion caused by the lean solution will be reduced.

[0025] Furthermore, the ester compounds include ethylene glycol borate, fatty alcohol ether phosphate, or vinyl ester.

[0026] Furthermore, the amino acid contains a sulfonic acid group and / or a carboxylic acid group.

[0027] Furthermore, the amino acid includes any one of methionine, taurine, serine, and cysteine.

[0028] Because amino acids contain amino groups, they can react with carbon dioxide, increasing the absorption efficiency of the absorbent. Amino acids also have stable antioxidant properties, acting as natural antioxidants that can resist impurity gases such as SO2 and NO. x It can cause deterioration or damage to the absorbent.

[0029] Furthermore, the mass ratio of the amino acid to the metal iodide is (1-5):1.

[0030] Furthermore, the iodide metal includes potassium iodide or sodium iodide.

[0031] Furthermore, the carbon dioxide absorbent is configured with a pH of 8.5–11 and a pKb of 4.0–7.0 at 30°C–40°C.

[0032] Furthermore, at 30°C to 40°C, the pKa of the aqueous solutions of the weak acid compound and the ester compound is 7.0 to 10.0.

[0033] Wherein, pKa is the acidity coefficient. The smaller the pKa value, the stronger the acidity; the larger the pKa value, the weaker the acidity.

[0034] pKb is the alkalinity coefficient. The smaller the pKb value, the stronger the alkalinity; the larger the pKb value, the weaker the alkalinity.

[0035] Secondly, this application provides a method for preparing a carbon dioxide absorbent, comprising the following steps: adding a weak acid compound solution and / or an ester compound solution, an antioxidant solution and water to an amine compound solution by weight percentage, and mixing them evenly to obtain the carbon dioxide absorbent.

[0036] Thirdly, this application provides an application of the above-described carbon dioxide absorbent or the carbon dioxide absorbent prepared by the above-described preparation method, including its application in a chemical amine solution decarbonization system.

[0037] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0038] (1) The carbon dioxide absorbent in this invention can effectively inhibit the degradation and corrosion of carbon capture solvents, and the antioxidants and corrosion inhibitors in the absorbent are consumed in very small amounts, which will not have a negative impact on the performance of the solution and the effect is sustainable.

[0039] (2) The antioxidant in this invention utilizes the non-consumption and stability of metal iodides to inhibit the possibility of degradation of amine molecules from the source. It is supplemented with amino acids to enhance the high-temperature oxidation resistance of the absorbent and ensure its removal capacity. Since the decarbonization absorbent cannot be completely regenerated, the corrosive effect of carbamates always exists. Therefore, the use of weak acid compounds or ester compounds can further reduce the corrosivity of the decarbonization solution and have a certain regeneration and energy-saving effect. Therefore, the carbon dioxide absorbent in this invention has good technical and economic efficiency. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 A schematic diagram of the experimental apparatus for testing oxidation degradation and corrosion is provided for embodiments of the present invention;

[0042] Figure 2 This is a graph showing the oxidation potential change of the carbon dioxide absorption liquid in Example 1 of the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0044] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0045] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0046] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0047] Example 1

[0048] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 1 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0049] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until there are no undissolved substances.

[0050] Example 2

[0051] This embodiment provides a carbon dioxide absorbent and its preparation method. Unlike Embodiment 1, the amine compound in this embodiment is 40 wt% diethanolamine (DEA), which, by weight percentage, includes 40 wt% diethanolamine, 1 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance is water.

[0052] The carbon dioxide absorbent is prepared by mixing diethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until there are no undissolved substances.

[0053] Example 3

[0054] This embodiment provides a carbon dioxide absorbent and its preparation method. Unlike Embodiment 1, the amine compound in this embodiment is 40 wt% diethylene glycolamine (DGA), which, by weight percentage, includes 40 wt% diethylene glycolamine, 1 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance is water.

[0055] The carbon dioxide absorbent is prepared by mixing diethylene glycolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until there are no undissolved substances.

[0056] Example 4

[0057] This embodiment provides a carbon dioxide absorbent and its preparation method. Unlike Example 1, the amine compound in this embodiment is 30 wt% methyl diethanolamine (MDEA) and 10 wt% ethanolamine (MEA), the weak acid compound is 2 wt% phosphoric acid, and the amino acid is 2 wt% taurine. By weight percentage, it includes 30 wt% methyl diethanolamine, 10 wt% ethanolamine, 2 wt% phosphoric acid, 2 wt% taurine, 1 wt% potassium iodide, and the balance is water.

[0058] The carbon dioxide absorbent is prepared by mixing methyldiethanolamine, ethanolamine, phosphoric acid, taurine, potassium iodide, and water in a certain proportion until there are no undissolved substances.

[0059] Example 5

[0060] This embodiment provides a carbon dioxide absorbent and its preparation method. Unlike Example 4, the amine compounds in this embodiment are 30 wt% methyl diethanolamine (MDEA) and 10 wt% diethanolamine (DEA). By weight percentage, it includes 30 wt% methyl diethanolamine, 10 wt% diethanolamine, 2 wt% phosphoric acid, 2 wt% taurine, 1 wt% potassium iodide, and the balance is water.

[0061] The carbon dioxide absorbent is prepared by mixing methyldiethanolamine, diethanolamine, phosphoric acid, taurine, potassium iodide, and water in a certain proportion until there are no undissolved substances.

[0062] Example 6

[0063] This embodiment provides a carbon dioxide absorbent and its preparation method. Unlike Example 4, the amine compound in this embodiment is 35 wt% methyl diethanolamine (MDEA) and 5 wt% piperazine (PZ). By weight percentage, it includes 35 wt% methyl diethanolamine, 5 wt% piperazine (PZ), 2 wt% phosphoric acid, 2 wt% taurine, 1 wt% potassium iodide, and the balance is water.

[0064] The carbon dioxide absorbent is prepared by mixing methyldiethanolamine, piperazine (PZ), phosphoric acid, taurine, potassium iodide, and water in a certain proportion until there are no undissolved substances.

[0065] Comparative Example 1

[0066] This comparative example provides a carbon dioxide absorbent that, unlike Example 1, contains only 30 wt% ethanolamine (MEA) and the remainder is water.

[0067] Comparative Example 2

[0068] This comparative example provides a carbon dioxide absorbent that, unlike Example 2, contains only 40 wt% diethanolamine (DEA) with the remainder being water.

[0069] Comparative Example 3

[0070] This comparative example provides a carbon dioxide absorbent that, unlike Example 3, contains only 40 wt% diethylene glycolamine (DGA) and the remainder is water.

[0071] Comparative Example 4

[0072] This comparative example provides a carbon dioxide absorbent that, unlike Example 4, contains only 30 wt% methyldiethanolamine (MDEA) and 10 wt% ethanolamine (MEA), with the remainder being water.

[0073] Comparative Example 5

[0074] This comparative example provides a carbon dioxide absorbent that, unlike Example 5, contains only 30 wt% methyl diethanolamine (MDEA) and 10 wt% diethanolamine (DEA), with the remainder being water.

[0075] Comparative Example 6

[0076] This comparative example provides a carbon dioxide absorbent that, unlike Example 5, contains only 35 wt% methyldiethanolamine (MDEA) and 5 wt% piperazine (PZ), with the remainder being water.

[0077] The performance of the carbon dioxide absorbents in Examples 1-6 and Comparative Examples 1-6 was tested.

[0078] exist Figure 1In the experimental setup shown, cylinder gas was used to simulate flue gas with a CO2 concentration of 12%, an O2 concentration of 5%, and an N2 concentration of 83%, at a flow rate of 250 ml / min. After absorption reached saturation at 40°C, the gas intake was stopped. An oil bath was used for heating at 120°C to regenerate the solution. This cycle was repeated for a total experimental period of 20 days. The test results are shown in Table 1. The oxidation potential of the carbon dioxide absorbent in Example 1 and Comparative Example 1 was measured over a period of 5 days. The test results are shown below. Figure 2 .

[0079] Table 1

[0080]

[0081] As can be seen from the data in Table 1, before the addition of weak acid and antioxidant, the content of heat-stable amine salts and organic degradation products in various amine absorbents is generally high. However, with the absorbent solution of the present invention, the content of heat-stable amine salts can generally be lower than 400 ppm with an inhibition rate of >90%, and the content of organic matter is lower than 10 ppm with an inhibition rate of 85-98%. This method is easy to implement, does not affect the performance of the absorbent, can improve the stability of the solution, extend the service life of the solvent, reduce the corrosion risk of the device, and can effectively reduce the operating cost of carbon capture devices.

[0082] from Figure 2 It can be seen that after adding 1 wt% potassium iodide, the redox potential of the ethanolamine MEA solution system in Example 1 and Comparative Example 1 without potassium iodide (solid line) increased faster and the final value was higher, indicating more severe oxidative degradation. The redox potential of the solution with potassium iodide (dashed line) increased slowly and the final value was lower, indicating the protective effect of the KI antioxidant, which limited the generation of oxidative free radicals.

[0083] Example 7

[0084] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0085] The carbon dioxide absorbent is prepared by mixing ethanolamine, methionine, potassium iodide and water in a certain proportion until the carbon dioxide absorbent is obtained.

[0086] Comparative Example 7

[0087] This comparative example provides a carbon dioxide absorbent that, unlike Example 7, does not contain methionine.

[0088] Example 8

[0089] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% methyl diethanolamine (MDEA), 10 wt% ethanolamine (MEA), 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0090] The carbon dioxide absorbent is prepared by mixing methyldiethanolamine, ethanolamine, methionine, potassium iodide, and water in a specific ratio to obtain the carbon dioxide absorbent.

[0091] Comparative Example 8

[0092] This comparative example provides a carbon dioxide absorbent that, unlike Example 8, does not contain methionine.

[0093] The performance of the carbon dioxide absorbent solutions in Examples 7, 8, 7, and 8 was tested, and the potassium iodide + amino acid combination was compared. Figure 1 The experimental setup in the experiment involved preparing an absorbent solution loaded with 80g of CO2 / L solution, regenerating it at 140℃, and then cycling it again. This process was repeated over a period of 7 days, and the test results are shown in Table 2.

[0094] Table 2

[0095]

[0096] As can be seen from the data in Table 2, the organic impurity content of the original absorbent system with added potassium iodide increased due to the increase in regeneration temperature, while the organic impurity content was significantly reduced after the addition of methionine.

[0097] Example 9

[0098] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 40 wt% ethanolamine (MEA), 2 wt% boric acid, 2 wt% methionine, 1% potassium iodide, and the balance being water.

[0099] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0100] Comparative Example 9

[0101] This comparative example provides a carbon dioxide absorbent, which differs from Example 9 in that it does not contain boric acid.

[0102] Example 10

[0103] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% methyl diethanolamine (MDEA), 10 wt% ethanolamine (MEA), 2 wt% boric acid, 2 wt% methionine, 1% potassium iodide, and the balance being water.

[0104] The carbon dioxide absorbent is prepared by mixing methyldiethanolamine, ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio to obtain the carbon dioxide absorbent.

[0105] Comparative Example 10

[0106] This comparative example provides a carbon dioxide absorbent that, unlike Example 10, does not contain boric acid.

[0107] The performance of the carbon dioxide absorbent solutions in Examples 9, 10, 9, and 10 was tested, and the combinations of potassium iodide + amino acids + weak acid were compared. Figure 1 The experimental setup in the experiment was prepared by loading an absorbent solution with 80g CO2 / L solution through the absorption process, and regenerated at temperatures of 120℃ and 110℃. The test results are shown in Table 3.

[0108] Table 3

[0109]

[0110]

[0111] As shown in Table 3, in the absorbent system containing the antioxidant potassium iodide, the addition of a certain amount of boric acid significantly reduced the CO2 content of the lean solution under the same regeneration conditions. Even when the regeneration temperature was lowered to 110℃, the absorbent system with added weak acid still exhibited good regeneration performance. It should be noted that even without the addition of antioxidants, the CO2 content of the lean solution was reduced.

[0112] Example 11

[0113] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 1 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0114] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0115] Example 12

[0116] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 1 wt% boric acid, 1 wt% phosphoric acid, 1 wt% taurine, 1 wt% potassium iodide, and the balance being water.

[0117] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, phosphoric acid, taurine, potassium iodide, and water in a specific ratio until homogeneous.

[0118] Example 13

[0119] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 40 wt% diethanolamine (DEA), 1 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0120] The carbon dioxide absorbent is prepared by mixing diethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0121] Example 14

[0122] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 40 wt% diethanolamine (DEA), 1 wt% boric acid, 1 wt% phosphoric acid, 1 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0123] The carbon dioxide absorbent is prepared by mixing diethanolamine, boric acid, phosphoric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0124] Example 15

[0125] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 35 wt% methyl diethanolamine (MDEA), 5 wt% piperazine (PZ), 1 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0126] Example 16

[0127] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 35 wt% methyl diethanolamine (MDEA), 5 wt% piperazine (PZ), 1 wt% boric acid, 1 wt% phosphoric acid, 1 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0128] Comparative Example 11

[0129] This comparative example provides a carbon dioxide absorbent containing only 30 wt% ethanolamine (MEA) with the remainder being water.

[0130] Comparative Example 12

[0131] This comparative example provides a carbon dioxide absorbent containing only 40 wt% diethanolamine (DEA), with the remainder being water.

[0132] Comparative Example 13

[0133] This comparative example provides a carbon dioxide absorbent containing only 35 wt% methyldiethanolamine (MDEA) and 5 wt% piperazine (PZ), with the remainder being water.

[0134] The performance of the carbon dioxide absorbents in Examples 11-16 and Comparative Examples 11-13 was tested.

[0135] Similarly, Figure 1 The experimental setup involved preparing an absorbent solution loaded with 77g of CO2 / L solution and regenerating it in an oil bath at 80℃ (a condition most prone to corrosion in carbon capture devices, characterized by high load, high erosion). Metal test pieces were suspended inside the tank and stirred. The experiment lasted 7 days. The measurement method was the weight loss method using the test piece, made of Q345R (20#) carbon steel. The rotation speed was 500 rpm, and the suspension time was 300 hours. The corrosion rate was calculated using the following formula:

[0136] V = k(w1 - w2) / (F × t × y)

[0137] Among them, v is the corrosion rate, k is a constant of 87.6 mm / a, w1 is the original weight of the sample, w2 is the weight after the sample is attached, F is the surface area of ​​the sample, t is the attachment time, and y is the metal density (7.85 for carbon steel). The measured corrosion rates are shown in Table 4.

[0138] Table 4

[0139]

[0140]

[0141] The results in the table show that after adding antioxidants and corrosion inhibitors to the provided comparative examples to prepare the carbon dioxide absorbent liquid described in this invention, the annual corrosion rate decreased significantly, with an inhibition rate exceeding 80% and a stable value less than 0.1 mm, meeting the corrosion control requirements of the chemical industry for carbon steel equipment. As mentioned above, the reduction in corrosion rate is due to two reasons: firstly, the antioxidant component inhibits the generation of degradation corrosion products at the source; secondly, the corrosion inhibitor component effectively protects the metal surface, hindering further corrosion.

[0142] Example 17

[0143] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 1 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0144] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0145] Example 18

[0146] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 1 wt% boric acid, 2 wt% methionine, 2% potassium iodide, and the balance being water.

[0147] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0148] Comparative Example 14

[0149] This comparative example provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 1 wt% boric acid, 2 wt% methionine, 0.5 wt% potassium iodide, and the balance being water.

[0150] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0151] The total alkalinity content in the carbon dioxide absorbents prepared in Examples 17, 18, and 14 was measured, and similarly... Figure 1In the experimental setup shown, cylinder gas was used to simulate flue gas with a CO2 concentration of 12%, an O2 concentration of 5%, and an N2 concentration of 83%, at a flow rate of 250 ml / min. After absorption reached saturation at 40°C, the gas intake was stopped. An oil bath was used to heat the solution at 120°C for regeneration. This cycle was repeated for a total experimental period of 20 days. The test results are shown in Table 5.

[0152] Table 5

[0153]

[0154] As can be seen from the data in Table 5, adding only 1.0 wt% KI is just as effective as adding 2.0 wt% KI, with less amine loss and effective inhibition of oxidative degradation; however, when the concentration is reduced to 0.5 wt%, the total alkalinity decreases significantly, indicating that the amine loss is large and oxidative degradation is not effectively inhibited.

[0155] Example 19

[0156] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 0.5 wt% boric acid, 1 wt% methionine, 2 wt% potassium iodide, and the balance being water.

[0157] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0158] Comparative Example 15

[0159] This comparative example provides a carbon dioxide absorbent comprising, by weight percentage, 30 wt% ethanolamine (MEA) and the balance being water.

[0160] The total alkalinity content in the carbon dioxide absorbent solutions of Example 19 and Comparative Example 15 was detected, and similarly... Figure 1 In the experimental setup shown, cylinder gas was used to simulate flue gas with a CO2 concentration of 12%, an O2 concentration of 5%, an N2 concentration of 83%, and a flow rate of 250 ml / min. After the gas was absorbed to saturation at 40°C, the gas intake was stopped. The solution was then regenerated by heating in an oil bath at 120°C. This cycle was repeated for 20 days. The test results are shown in Table 6.

[0161] Table 6

[0162]

[0163]

[0164] As can be seen from the data in Table 6, the total alkalinity of the carbon dioxide absorbent prepared using the formulation of the present invention was higher than that of Comparative Example 15 throughout the experimental period, and the total alkalinity of the carbon dioxide absorbent prepared in the present invention changed very little over time.

[0165] Comparative Example 16

[0166] The comparative example provides a carbon dioxide absorbent comprising, by weight percentage, 30 wt% ethanolamine (MEA), 2 wt% boric acid, 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0167] Example 20

[0168] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 1 wt% boric acid, 1 wt% ethylene glycol borate, 2 wt% methionine, 1 wt% potassium iodide, and the balance being water.

[0169] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0170] Example 21

[0171] This embodiment provides a carbon dioxide absorbent and its preparation method, comprising, by weight percentage, 30 wt% ethanolamine (MEA), 2 wt% ethylene glycol borate, 2 wt% methionine, 1% potassium iodide, and the balance being water.

[0172] The carbon dioxide absorbent is prepared by mixing ethanolamine, boric acid, methionine, potassium iodide, and water in a specific ratio until homogeneous.

[0173] The CO2 content and regeneration temperature of the lean absorbent in Examples 20, 21, and 16 were measured. Figure 1 In the experimental setup shown, an absorbent solution with a CO2 content of 70 g / L was prepared and regenerated by heating in an oil bath for 20 min, and this cycle was repeated 5 times. The test results are shown in Table 7.

[0174] Table 7

[0175] sample <![CDATA[CO₂ content in lean solution, g / L]]> Regeneration temperature, °C Comparative Example 16 12.4 110 Example 20 9.2 105 Example 21 9.7 100

[0176] As can be seen from the data in Table 7, after replacing boric acid with ethylene glycol borate in the preparation of the carbon dioxide absorbent of this invention, it has a beneficial effect on the quality of lean solution regeneration and the regeneration temperature (energy consumption). With the addition of ethylene glycol borate and the reduction of boric acid, the CO2 content of the lean solution decreases significantly, and the regeneration temperature further decreases. Even at 100°C, the quality of lean solution regeneration can be maintained well. This is mainly attributed to the fact that ethylene glycol is produced by the hydrolysis of esters, which can increase the specific heat of the solution system and reduce the regeneration energy consumption.

[0177] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. It is obvious to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and therefore all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within this application.

Claims

1. A carbon dioxide absorbent, characterized in that, By weight percentage, it includes 15wt% to 40wt% amine compounds, 0.5wt% to 5wt% weak acid compounds and / or ester compounds, 0.5wt% to 2wt% antioxidants, and the balance being water; The antioxidant is a mixture of metal iodide and amino acids.

2. The carbon dioxide absorbent according to claim 1, characterized in that, The amine compounds contain amino, carboxyl, and / or alkyl groups in their molecules.

3. A carbon dioxide absorbent according to claim 1 or 2, characterized in that, The amine compounds include alkyl alcoholamines or alkylamines.

4. The carbon dioxide absorbent according to claim 3, characterized in that, The alkyl alcoholamines include any one or more combinations of ethanolamine, diethylene glycolamine, diethanolamine, methyldiethanolamine, hydroxyethylenediamine, 2-amino-2-methyl-1-propanol, and 2-piperidineethanol.

5. The carbon dioxide absorbent according to claim 3, characterized in that, The alkylamine includes any one or more combinations of diethylenetriamine, 1,6-ethylenediamine, piperazine, aminoethylpiperazine, and 2-methylpiperazine.

6. The carbon dioxide absorbent according to claim 1, characterized in that, The weak acid compound includes boric acid, phosphoric acid, or glacial acetic acid.

7. The carbon dioxide absorbent according to claim 1, characterized in that, The ester compounds include ethylene glycol borate, fatty alcohol ether phosphate, or vinyl ester.

8. The carbon dioxide absorbent according to claim 1, characterized in that, The amino acid contains a sulfonic acid group and / or a carboxylic acid group.

9. A carbon dioxide absorbent according to claim 8, characterized in that, The amino acid includes any one of methionine, taurine, serine, and cysteine.

10. A carbon dioxide absorbent according to claim 1, characterized in that, The mass ratio of the amino acid to the metal iodide is (1-5):

1.

11. A carbon dioxide absorbent according to claim 1, characterized in that, The iodide metals include potassium iodide or sodium iodide.

12. The carbon dioxide absorbent according to claim 1, characterized in that, The carbon dioxide absorbent is prepared at 30℃ to 40℃ with a pH of 8.5 to 11 and a pKb of 4.0 to 7.

0.

13. The carbon dioxide absorbent according to claim 1, characterized in that, At 30°C to 40°C, the pKa of the aqueous solutions of the weak acid compound and the ester compound is 7.0 to 10.

0.

14. A method for preparing the carbon dioxide absorbent according to any one of claims 1 to 13, characterized in that, Includes the following steps: Add a weak acid compound solution and / or an ester compound solution, an antioxidant solution, and water to the amine compound solution according to weight percentage, and mix thoroughly to obtain the carbon dioxide absorbent.

15. The application of a carbon dioxide absorbent according to any one of claims 1 to 13, or a carbon dioxide absorbent prepared by the preparation method according to claim 14, characterized in that, This includes applications in decarbonization systems for chemical amine solutions.

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