Inhibitors for inhibiting oxidative degradation of amine absorbents and use thereof

Abstract

The application discloses an inhibitor for inhibiting oxidative degradation of an amine absorbent, the amine absorbent and application thereof, and belongs to the technical field of gas separation and purification. The inhibitor is a combination of iodide and a metal ion chelating agent, and the molar ratio of the iodide to the metal ion chelating agent is (80-300):(5-20). The amine absorbent comprises a chain polyamine, the inhibitor and a solvent. The inhibitor of the application can efficiently inhibit oxidative degradation of the amine absorbent in the presence of metal ions and under long-time contact of the amine absorbent with oxygen, and the inhibitor of the application is suitable for various amine absorbents, especially various chain polyamines.

Description

Technical Field

[0001] This invention belongs to the field of gas separation and purification technology, specifically relating to inhibitors for suppressing the oxidative degradation of amine absorbents, amine absorbents, and their applications. Background Technology

[0002] The extensive use of traditional fossil fuels has led to a continuous increase in atmospheric CO2 concentrations. High CO2 levels exacerbate the greenhouse effect, increase the frequency of extreme weather events, and pose significant challenges to human development. The power industry and industrial processes such as steel, oil, and cement contribute the vast majority of carbon emissions. Currently, non-fossil energy is developing rapidly, but most power systems still rely on thermal power. Carbon dioxide capture, utilization, and storage (CCUS) technology is an effective means of reducing CO2 emissions from large sources. CCUS is a fundamental technology for achieving low-carbon utilization of fossil fuels.

[0003] In the technical aspects of CCUS (Carbon Capture and Sterilization), carbon capture is the most expensive, and its high cost severely restricts the large-scale commercial operation of carbon capture technology. Based on the sequence of the carbon capture and combustion processes, carbon capture technologies can be divided into pre-combustion carbon capture, oxy-fuel combustion, and post-combustion carbon capture. Post-combustion carbon capture can be used without equipment modification. Among post-combustion carbon capture technologies, chemical absorption is currently the most mature, characterized by fast absorption rates, the ability to handle low partial pressure CO2 flue gas, and high equipment and process maturity. Numerous demonstration projects have already been implemented.

[0004] Amine CO2 capture using amine scrubbing technology is considered one of the most promising technologies in chemical absorption methods. The most commonly used amines in this technology are monoethanolamine (MEA), methyldiethanolamine (MDEA), and diethanolamine (DEA). However, with the expansion of pilot and demonstration projects, degradation of amine absorbents has become a significant obstacle to the long-term stable operation of these projects. In MEA systems, absorbent replenishment costs due to amine degradation account for approximately 10% of the total cost, with losses reaching 1.4 kg / tCO2. Amine absorbent degradation mainly falls into two categories: oxidative degradation caused by the approximately 5% oxygen content in the flue gas in the absorption tower, and thermal degradation caused by high temperatures in the desorption tower. Oxidative degradation is the primary cause of absorbent loss.

[0005] When screening carbon dioxide absorbents, suitable amine absorbents should possess high CO2 capture capacity, high CO2 absorption rate, low heat of reaction, low volatility, and appropriate physical properties. From the perspective of carbon dioxide absorption performance, primary amines > secondary amines > tertiary amines, and multiple amino functional groups give them stronger carbon dioxide absorption capacity and absorption rate. Therefore, the use of chain polyamines has extremely broad application prospects for obtaining high carbon dioxide absorption and desorption performance. Currently, there are many studies on monoamine solutions such as ethylenediamine (EDA), 1,3-propanediamine (PDA), 1,4-butanediamine (Putrescine), diethylenetriamine (DETA), hydroxyethylethylenediamine (AEEA), and triethylenetetramine (TETA), all of which can achieve high carbon dioxide capture performance. In addition, a large number of studies have also used these polyamines as the main absorbent in second-generation mixed amine absorbents and as the main absorbent in third-generation two-phase absorbents, achieving good carbon dioxide absorption and desorption performance.

[0006] However, during the absorption process, flue gas containing a small amount of oxygen reacts with organic amines upon entering the absorption tower, causing the amines to lose their oxidation activity and reducing carbon dioxide capture performance. Furthermore, the amine solution and its degradation products corrode equipment during circulation, and the generated metal ions further catalyze the oxidation of organic amines, increasing operating costs. In the conventional ethanolamine process, the replenishment of organic amines accounts for nearly 10% of the total carbon capture cost. For chain polyamines, they are more prone to oxidative degradation than ethanolamines. The increased number of primary and secondary amines and the increased chain length make it easier for the lone pair electrons of nitrogen atoms to be attacked in the presence of oxygen, forming free radicals, thus continuously undergoing oxidative degradation through a chain reaction. In addition, the catalytic effect of metal ions is strong; once metal ions such as iron and copper are present in the solution, the oxidation rate is further accelerated.

[0007] As research on the absorption rate, absorption capacity, and regeneration energy consumption of amine absorbents continues to mature, the severe oxidative degradation that is prevalent in pilot and demonstration projects hinders the large-scale commercial operation of carbon capture projects. Therefore, there is an urgent need to find efficient inhibition methods and develop inhibitors that effectively suppress the oxidative degradation of organic amines, thereby reducing the cost associated with organic amine degradation.

[0008] CN112546840B proposes a two-phase carbon dioxide absorbent comprising a mixed aqueous solution of ethanolamine (MEA) and sulfolane (TMS) and an oxidation inhibitor, wherein the oxidation inhibitor is selected from glycerol, D-sorbitol, xylitol, or erythritol. The oxidation inhibitor selected in this scheme is only effective for absorbents with ethanolamine as the main component; the addition of erythritol only increases the MEA retention rate from 69.3% to 92.9% after 48 hours. Furthermore, alcohol-based oxygen scavenging inhibitors may be consumed during the process, failing to maintain the long-term oxidative stability of the absorbent.

[0009] CN115475486A discloses an antioxidant degradation phase change absorbent, its carbon dioxide capture method, and its application. Hydroxyethyl ethylenediamine is used as the main absorbent, sulfolane as the phase-separating agent, and a mixture of ascorbic acid and potassium iodide as the oxidation degradation inhibitor. In the organic amine system, ascorbic acid does not significantly inhibit oxidation degradation and may even accelerate it. Therefore, under the same conditions, the oxidation degradation rate of this absorbent system is only 7.83% lower than that of the 5 M MEA solution.

[0010] CN117244384A reports an antioxidant low-water amine solution for capturing carbon dioxide from flue gas and its application. The proposed solution suggests that adding sulfur-containing antioxidants and / or chelating agents to the low-water amine solution does not affect the reaction and significantly retains the content of the main absorbent, N-ethylethanolamine, reducing its degradation. However, the oxidation inhibition effect of this formulation is poor, only providing a weak inhibitory effect.

[0011] Chain-like polyamines are currently a research hotspot. Whether used as a single amine or as a major component of mixed amines and two-phase absorbents, these amines can achieve higher absorption rates and capacities. However, their high amino concentration makes them more susceptible to oxidative degradation than ethanolamines, which is detrimental to the stable operation of the system. Furthermore, metal ions generated from equipment corrosion can further catalyze the oxidative degradation of chain-like polyamines. Current research on oxidative degradation inhibitors is insufficient. Existing inhibitors only target specific carbon dioxide absorbent systems and cannot achieve highly efficient oxidative degradation inhibition. Moreover, most oxidative inhibitors are consumed over time, failing to maintain long-term performance in inhibiting the oxidative degradation of amine solutions. Summary of the Invention

[0012] To address at least one of the aforementioned technical problems, the present invention aims to provide an inhibitor for inhibiting the oxidative degradation of amine absorbents, amine absorbents themselves, and their applications. The inhibitor of the present invention can efficiently inhibit the oxidative degradation of amine absorbents under prolonged contact with oxygen and in the presence of metal ions. Furthermore, the inhibitor of the present invention is applicable to a variety of amine absorbents, especially various chain polyamines.

[0013] To achieve the above objectives, the first aspect of the present invention provides an inhibitor for inhibiting the oxidative degradation of amine absorbents, which is a combination of iodide and metal ion chelating agent, wherein the molar ratio of the iodide to the metal ion chelating agent is (80-300):(5-20).

[0014] According to a specific embodiment of the present invention, the iodide is an iodine-containing inorganic salt. Preferably, the iodide includes one or more of potassium iodide (KI), sodium iodide (NaI), lithium iodide (LiI), and ammonium iodide (NH4I).

[0015] According to a specific embodiment of the present invention, the metal ion chelating agent is a phosphate chelating agent. Preferably, the metal ion chelating agent includes one or more of the following: hydroxyethylidene diphosphonic acid (HEDP), diethylenetriaminepentamethylenephosphonic acid (DTPMPA), aminotrimethylenephosphonic acid (ATMP), ethylenediaminetetramethylenephosphonic acid (EDTMPA), hexamethylenediaminetetramethylenephosphonic acid (HDTMPA), and triethylenetetraaminehexamethylenephosphonic acid (TETHMP).

[0016] According to a specific embodiment of the present invention, the molar ratio of the iodide to the metal ion chelating agent is (80-300):(8-12).

[0017] The second aspect of the present invention provides the application of the above-mentioned inhibitor for inhibiting the oxidative degradation of amine absorbents in amine absorbents.

[0018] According to a specific embodiment of the present invention, the amine absorbent contains an organic amine, which includes one or more of the following: chain polyamines, chain monoamines, cyclic amines, and sterically hindered amines. Preferably, the organic amine includes chain polyamines.

[0019] According to a specific embodiment of the present invention, the amine absorbent is an amine absorbent for capturing CO2 gas. Preferably, the amine absorbent is an amine absorbent for capturing CO2-containing gas emitted from one or more emission sources such as coal-fired power plants, gas-fired power plants, oil refineries, steel mills, and cement plants.

[0020] A third aspect of the present invention provides an amine absorbent comprising: a chain polyamine, the above-mentioned inhibitor for inhibiting the oxidative degradation of the amine absorbent, and a solvent; wherein the chain polyamine has a content of 20-40 wt%, the iodide content in the inhibitor for inhibiting the oxidative degradation of the amine absorbent is 80-300 mmol / kg, and the metal ion chelating agent content in the inhibitor for inhibiting the oxidative degradation of the amine absorbent is 5-20 mmol / kg.

[0021] According to a specific embodiment of the present invention, the content of the metal ion chelating agent is 8-12 mmol / kg.

[0022] According to a specific embodiment of the present invention, the chain polyamine is a chain polyamine containing primary and / or secondary amino groups. Preferably, the chain polyamine includes one or more of ethylenediamine (EDA), 1,3-propanediamine (PDA), 1,4-butanediamine (Putrescine), diethylenetriamine (DETA), hydroxyethylethylenediamine (AEEA), and tetraethylenepentamine (TEPA).

[0023] According to a specific embodiment of the present invention, the solvent is water.

[0024] The fourth aspect of this invention provides the application of the above-mentioned amine absorbent in carbon dioxide capture.

[0025] According to a specific embodiment of the present invention, the application includes the following steps: contacting a gas mixture containing carbon dioxide with the amine absorbent to capture carbon dioxide; and desorbing the amine absorbent after capturing carbon dioxide to obtain a regenerated amine absorbent.

[0026] According to a specific embodiment of the present invention, the contact between the gas mixture containing carbon dioxide and the amine absorbent is carried out in an absorption tower, wherein the temperature of the amine absorbent entering the absorption tower is 20-60°C, and the pressure at the bottom of the absorption tower is 0-20 kPa.

[0027] According to a specific embodiment of the present invention, the desorption of the amine absorbent after capturing carbon dioxide is carried out in a regeneration tower, the desorption temperature is 80-150°C, and the pressure at the top of the regeneration tower is 0-400 kPa.

[0028] According to a specific embodiment of the present invention, the gas mixture containing carbon dioxide comes from one or more emission sources such as coal-fired power plants, gas-fired power plants, oil refineries, steel mills, and cement plants.

[0029] The present invention has at least the following beneficial effects: The iodide and metal ion chelating agent in the inhibitor of this invention have a synergistic effect. In the early stage of oxidative degradation of amine absorbents, oxygen oxidation is dominant, and iodide can effectively inhibit the oxidative degradation of organic amines. As the operating time increases, the concentration of metal ions (especially iron ions) in the absorbent increases due to equipment corrosion. At this time, the metal ion chelating agent can quickly chelate the metal ions (especially iron ions) in the absorbent, inhibiting their catalytic oxidative degradation of organic amines. This synergistic effect enables the inhibitor of this invention to achieve a significantly improved oxidative degradation inhibition effect compared to using these two components alone. The inhibitor of this invention has a strong ability to inhibit oxidative degradation, and it has a highly efficient effect on inhibiting the oxidative degradation of amine absorbents, especially those containing chain polyamines. Even under prolonged contact with oxygen and in the presence of metal ions, the chain polyamines, which are most severely oxidized, can almost not undergo oxidative degradation, achieving 100% inhibition of the oxidative degradation of organic amines, improving the stability of the carbon capture system, and reducing the operating cost of carbon capture projects. In addition, the components of the inhibitor of this invention have a simple structure, are easy to obtain, and have low cost. They are added in small amounts to the absorbent and have high inherent stability. Moreover, the inhibitor of the present invention has broad applicability and is suitable for a variety of amine absorbents, especially various chain polyamines. Furthermore, the addition of the inhibitor of the present invention does not affect the original carbon dioxide capture performance of the amine absorbent. Attached Figure Description

[0030] Figure 1 The curve shows the amine retention rate of the inhibitor-free amine absorbent in Comparative Example 1 as a function of degradation time.

[0031] Figure 2 The curves showing the amine retention rate of amine absorbents with different antioxidants added in Comparative Example 2 as a function of degradation time.

[0032] Figure 3 The curves showing the amine retention rate of amine absorbents with different added iodides as shown in Comparative Example 3 are as follows:

[0033] Figure 4 The curves showing the amine retention rate of amine absorbents with different concentrations of NaI added in Comparative Example 4 as a function of degradation time.

[0034] Figure 5 Adding 1 mM Fe to Comparative Example 5 3+ The curve showing the change in amine retention rate of amine absorbents containing iodides over degradation time.

[0035] Figure 6 The curves show the amine retention rate as a function of degradation time for amine absorbents containing different inhibitors and amine absorbents without inhibitors in Comparative Examples 6 and 7 and Examples 1 and 2.

[0036] Figure 7The curves showing the amine retention rate of amine absorbents added for compound inhibitors and individual components as a function of degradation time.

[0037] Figure 8 The absorption performance curves are for amine absorbents with and without inhibitors.

[0038] Figure 9 The desorption performance curves are for amine absorbents with and without inhibitors.

[0039] Figure 10 The curve shows the amine retention rate of the amine absorbent in Example 3 as a function of degradation time.

[0040] Figure 11 The curve shows the amine retention rate of the amine absorbent in Example 4 as a function of degradation time.

[0041] Figure 12 The curve shows the amine retention rate of the amine absorbent in Example 5 as a function of degradation time.

[0042] Figure 13 The curve shows the amine retention rate of the amine absorbent in Example 6 as a function of degradation time.

[0043] Figure 14 The curve shows the amine retention rate of the amine absorbent in Example 7 as a function of degradation time. Detailed Implementation

[0044] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0045] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0046] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0047] It should be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0048] The endpoints and any values ​​of the ranges disclosed in this invention 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 in this invention.

[0049] According to a specific embodiment of the first aspect of the present invention, the present invention provides an inhibitor for inhibiting the oxidative degradation of amine absorbents, which is a combination of iodide and metal ion chelating agent, wherein the molar ratio of the iodide to the metal ion chelating agent is (80-300):(5-20).

[0050] In the inhibitor of this invention, the synergistic effect of iodide and metal ion chelating agent enables a significant improvement in the oxidative stability of organic amines under long-term industrial operating conditions. Firstly, iodide plays a positive role in several ways. The presence of iodine inhibits the reaction of organic amine solutions with oxygen. Furthermore, iodide reduces the solubility of oxygen in the solution due to the salting-out effect, thus contributing to its highly efficient inhibitory effect on organic amine oxidation. Secondly, the inventors discovered that the inhibitory effect of iodide on oxidative degradation weakens under iron-containing conditions. This invention employs a metal ion chelating agent to chelate iron ions generated by corrosion, blocking their catalytic effect on free radical chain reactions and inhibiting the oxidative degradation of organic amines catalyzed by iron ions. By controlling the iodide and metal ion chelating agent within the scope of this invention, their synergistic effect can be maximized. Simultaneously, the inhibitor of this invention maintains high self-stability during the recycling of amine absorbents (i.e., the adsorption and desorption process), and can exert its inhibitory effect on the oxidative degradation of organic amines for a long time. Therefore, the inhibitor of this invention can significantly inhibit the oxidative degradation of organic amines under prolonged contact with oxygen and in the presence of iron ions. Furthermore, the inhibitor of this invention can be stored and recycled simultaneously with amine absorbents without affecting CO2 absorption performance or interfering with subsequent regeneration and gas separation processes. Especially for chain polyamines, this invention can solve the problem of severe oxidative degradation that hinders their large-scale commercial operation while maintaining their excellent carbon dioxide capture performance.

[0051] In some embodiments, the iodide comprises an iodine-containing inorganic salt. Preferably, the iodide comprises one or more of potassium iodide (KI), sodium iodide (NaI), lithium iodide (LiI), and ammonium iodide (NH4I). More preferably, the iodide is sodium iodide and / or lithium iodide. More preferably, the iodide is sodium iodide. This invention uses an iodine-containing inorganic salt as one of the components of the inhibitor. The presence of iodine hinders the reaction of organic amine solutions with oxygen. Furthermore, the hundreds of mmol / kg level of iodine-containing inorganic salt in the absorbent reduces the solubility of oxygen in the solution due to the salting-out effect, thereby reducing the oxygen content of the reactants in the oxidation reaction, thus contributing to its highly efficient inhibition of organic amine oxidation. Therefore, iodine-containing inorganic salts can inhibit the oxidative degradation of organic amines through a combination of physical and chemical actions. In addition, the inventors of this invention have found that sodium iodide and lithium iodide, compared to ammonium iodide and potassium iodide, have a more prominent inhibitory effect on the oxidative degradation of chain polyamines, which may be related to the ionic characteristics of the cations themselves. Meanwhile, considering the cost of the inhibitor, sodium iodide is the optimal iodide for this invention.

[0052] In some embodiments, the metal ion chelating agent is a phosphoric acid chelating agent. Preferably, the metal ion chelating agent includes one or more of the following: hydroxyethylidene diphosphonic acid (HEDP), diethylenetriaminepentamethylenephosphonic acid (DTPMPA), aminotrimethylenephosphonic acid (ATMP), ethylenediaminetetramethylenephosphonic acid (EDTMPA), hexamethylenediaminetetramethylenephosphonic acid (HDTMPA), and triethylenetetraaminehexamethylenephosphonic acid (TETHMP). This invention uses a phosphoric acid chelating agent, which, compared to other metal ion chelating agents, can better exert a synergistic effect with iodine-containing inorganic salts, thereby achieving a better effect in inhibiting the oxidative degradation of organic amines. Furthermore, the phosphoric acid chelating agent of this invention mainly relies on the strong electron-donating ability of multiple phosphonic acid groups to form a multidentate cage-like stable coordination structure, thereby more efficiently inhibiting the oxidative degradation of chain polyamines.

[0053] In some embodiments, the molar ratio of the iodide to the metal ion chelating agent is (80-300):(8-12).

[0054] The iodide and metal ion chelating agent in the inhibitor of the present invention can be stored separately and then added to the amine absorbent in the above proportions when used.

[0055] According to a specific embodiment of the second aspect of the present invention, the present invention provides the application of the above-mentioned inhibitor for inhibiting the oxidative degradation of amine absorbents in amine absorbents.

[0056] In some embodiments, the amine absorbent contains an organic amine, which includes one or more of the following: chain polyamines, chain monoamines, cyclic amines, and sterically hindered amines. Preferably, the organic amine includes chain polyamines.

[0057] In post-combustion CO2 capture systems, amine absorbents are susceptible to oxidative degradation during long-term operation. This is especially true when residual oxygen in the flue gas interacts with soluble iron ions in the system, intensifying the oxidation reaction and leading to the loss of organic amines and the accumulation of degradation products. This, in turn, causes equipment corrosion and a decline in carbon capture performance. Compared to traditional monoamine absorbents, chain polyamines, containing multiple amine groups, exhibit stronger CO2 absorption capacity and are highly promising carbon capture absorbents. However, the degradation behavior of chain polyamines is more complex, with a faster oxidation rate, and currently, effective inhibition methods are lacking. This invention utilizes a combination of iodides and metal ion chelators as inhibitors. The synergistic effect between these two agents significantly inhibits the oxidative degradation of chain polyamines under prolonged contact with oxygen and in the presence of iron ions.

[0058] In some embodiments, the amine absorbent is an amine absorbent for capturing CO2 gas. Preferably, the amine absorbent is an amine absorbent for capturing CO2-containing gas emitted from one or more large CO2 emission sources such as coal-fired power plants, gas-fired power plants, oil refineries, steel mills, and cement plants.

[0059] According to a specific embodiment of a third aspect of the present invention, the present invention provides an amine absorbent comprising: a chain polyamine, the above-mentioned inhibitor for inhibiting the oxidative degradation of the amine absorbent, and a solvent; wherein the content of the chain polyamine is 20-40 wt%, the content of iodide in the inhibitor for inhibiting the oxidative degradation of the amine absorbent is 80-300 mmol / kg, and the content of metal ion chelating agent in the inhibitor for inhibiting the oxidative degradation of the amine absorbent is 5-20 mmol / kg. The above contents are calculated based on the total weight of the chain polyamine and the solvent.

[0060] In some embodiments, the content of the metal ion chelating agent is 8-12 mmol / kg.

[0061] In some embodiments, the chain polyamine is a chain polyamine containing primary and / or secondary amino groups. The term "multi-functional" refers to two or more components, such as diamines, triamines, tetraamines, pentaamines, etc. Preferably, the chain polyamine includes one or more of ethylenediamine (EDA), 1,3-propanediamine (PDA), 1,4-butanediamine (Putrescine), diethylenetriamine (DETA), hydroxyethylethylenediamine (AEEA), and tetraethylenepentamine (TEPA). The structural formulas of these chain polyamines are shown below: .

[0062] The inhibitors of this invention are particularly suitable for chain polyamine absorbents containing primary and / or secondary amine groups, and have wide applicability in industrial flue gas CO2 absorption systems. Even with a small amount added to the absorbent, the inhibitors of this invention can achieve 100% inhibition of oxidative degradation in chain polyamine absorbents, which suffer the most severe oxidative degradation. Therefore, for short-chain monoamines with simpler molecular structures, cyclic amines with inherently higher oxidative stability, and sterically hindered amines, the inhibitors of this invention require only trace amounts to achieve complete inhibition of the oxidative degradation of organic amines.

[0063] In some embodiments, the solvent is water.

[0064] In some embodiments, the preparation method of the amine absorbent may include the following steps: mixing a chain polyamine with a solvent to obtain an amine solution; adding the iodide and metal ion chelating agent in the inhibitor to the amine solution, and stirring evenly at 25-35°C (to ensure that the inhibitor is fully dissolved and dispersed) to obtain the amine absorbent.

[0065] According to a specific embodiment of the fourth aspect of the present invention, the present invention provides the application of the above-described amine absorbent in carbon dioxide capture.

[0066] In some embodiments, the application includes the following steps: contacting a gas mixture containing carbon dioxide with the amine absorbent to capture carbon dioxide; and desorbing the amine absorbent after capturing carbon dioxide to obtain a regenerated amine absorbent.

[0067] In some embodiments, the contact between the carbon dioxide-containing gas mixture and the amine absorbent is carried out in an absorption tower, wherein the temperature of the amine absorbent entering the absorption tower is 20-60°C, and the bottom pressure of the absorption tower is 0-20 kPa.

[0068] In some embodiments, the desorption of the amine absorbent after capturing carbon dioxide is carried out in a regeneration tower, the desorption temperature (i.e., the temperature of the amine absorbent in the reboiler of the regeneration tower) is 80-150°C, and the pressure at the top of the regeneration tower is 0-400 kPa.

[0069] In some embodiments, the carbon dioxide-containing gas mixture originates from one or more large CO2 emission sources, such as coal-fired power plants, gas-fired power plants, oil refineries, steel mills, and cement plants.

[0070] The technical solutions of the present invention are specifically illustrated below through embodiments, but the present invention is not limited to these embodiments. Of course, various modifications can be made within the scope of the key points of the present invention.

[0071] Test method: Amine Retention Rate: The amine retention rate was used to assess the oxidative degradation of organic amines in the experiment. Samples taken at different times were placed in a gas chromatograph for testing to obtain the mass ratio of amines in the solution at different time points. Then, the ratio of amines in the initial solution... By comparison, the amine retention rate in the solution at different times can be calculated using formula (1). .

[0072] (1)

[0073] Comparative Example 1

[0074] This comparative example provides various amine absorbents, namely 30 wt% MEA aqueous solution, 30 wt% AEEA aqueous solution, and 30 wt% DETA aqueous solution.

[0075] These absorbents were each loaded with 1.2 mol CO2 / mol amine. Oxidative degradation tests were conducted on these absorbents in a pure oxygen atmosphere at 300 kPa, with the absorbent temperature maintained at 60°C during the tests. The amine retention rates of each absorbent were obtained, and the results are as follows: Figure 1 As shown. Furthermore, for a 30 wt% DETA aqueous solution, 1 mM Fe was further added. 3+ Under the above conditions, the oxidative degradation test was performed, and the amine retention rate results are as follows: Figure 1 As shown.

[0076] Depend on Figure 1 It can be seen that the amine retention rate of chain polyamines decreases at a higher rate with degradation time than that of MEA, especially in the presence of iron ions, the degree of oxidative degradation of DETA is significantly improved.

[0077] Comparative Example 2

[0078] This comparative example provides several amine absorbents: a 30 wt% DETA aqueous solution (i.e., without inhibitor), a 30 wt% DETA aqueous solution containing 200 mmol / kg KI, a 30 wt% DETA aqueous solution containing 200 mmol / kg sodium tartrate, a 30 wt% DETA aqueous solution containing 200 mmol / kg carbazide, and a 30 wt% DETA aqueous solution containing 200 mmol / kg hydroquinone. The inhibitor content in these absorbents is based on the weight of a 30 wt% DETA aqueous solution.

[0079] These absorbents were each loaded with 1.2 mol CO2 / mol amine. Oxidative degradation tests were conducted on these absorbents in a pure oxygen atmosphere at 300 kPa, with the absorbent temperature maintained at 60°C during the tests. The amine retention rates of each absorbent were obtained, and the results are as follows: Figure 2 As shown.

[0080] Depend on Figure 2 It can be seen that among antioxidants such as iodine-containing inorganic salts, sodium tartrate, carbazide, and hydroquinone, iodine-containing inorganic salts exhibit the best oxidative degradation inhibition effect on chain polyamines.

[0081] Comparative Example 3

[0082] This comparative example provides several amine absorbents: a 30 wt% DETA aqueous solution (i.e., without inhibitor), a 30 wt% DETA aqueous solution containing 200 mmol / kg NaI, a 30 wt% DETA aqueous solution containing 200 mmol / kg LiI, a 30 wt% DETA aqueous solution containing 200 mmol / kg NH4I, and a 30 wt% DETA aqueous solution containing 200 mmol / kg KI. The inhibitor content in these absorbents is based on the weight of a 30 wt% DETA aqueous solution.

[0083] These absorbents were each loaded with 1.2 mol CO2 / mol amine. Oxidative degradation tests were conducted on these absorbents in a pure oxygen atmosphere at 300 kPa, with the absorbent temperature maintained at 60°C during the tests. The amine retention rates of each absorbent were obtained, and the results are as follows: Figure 3 As shown.

[0084] Depend on Figure 3 It can be seen that the selection of cations can enhance the inhibitory effect of iodine-containing inorganic salts on the oxidative degradation of chain polyamines. At an addition concentration of 200 mmol / kg, NaI, LiI, and NH4I all achieve better results than KI, especially NaI and LiI, which enable DETA aqueous solution to maintain a retention rate of about 86% after 100 h of oxidative degradation. This may be related to the ionic characteristics of the cations themselves. Therefore, the iodine-containing inorganic salts of this invention can all achieve good inhibitory effects on the oxidative degradation of chain polyamines.

[0085] Comparative Example 4

[0086] This comparative example provides several amine absorbents: a 30 wt% DETA aqueous solution (i.e., without inhibitor), a 30 wt% DETA aqueous solution containing 100 mmol / kg NaI, a 30 wt% DETA aqueous solution containing 200 mmol / kg NaI, and a 30 wt% DETA aqueous solution containing 300 mmol / kg NaI. The inhibitor content in these absorbents is based on the weight of a 30 wt% DETA aqueous solution.

[0087] These absorbents were each loaded with 1.2 mol CO2 / mol amine. Oxidative degradation tests were conducted on these absorbents in a pure oxygen atmosphere at 300 kPa, with the absorbent temperature maintained at 60°C during the tests. The amine retention rates of each absorbent were obtained, and the results are as follows: Figure 4 As shown.

[0088] Depend on Figure 4 It can be seen that NaI has an excellent effect in inhibiting the oxidative degradation of organic amines. For chain polyamines such as DETA, which are subject to severe oxidative degradation, NaI can prevent them from undergoing degradation at an addition concentration of 300 mmol / kg. After 125 h of oxidative degradation experiment, the retention rate of DETA in the solution can be maintained at about 100%.

[0089] Comparative Example 5

[0090] This comparative example provides several amine absorbents: a 30 wt% DETA aqueous solution (i.e., without inhibitor), a 30 wt% DETA aqueous solution containing 200 mmol / kg NaI, a 30 wt% DETA aqueous solution containing 200 mmol / kg LiI, a 30 wt% DETA aqueous solution containing 200 mmol / kg NH4I, and a 30 wt% DETA aqueous solution containing 200 mmol / kg KI. The inhibitor content in these absorbents is based on the weight of a 30 wt% DETA aqueous solution.

[0091] These absorbents were each loaded with 1.2 mol CO2 / mol amine. Furthermore, 1 mM Fe was added to each of these absorbents. 3+ Then, these absorbents were subjected to oxidative degradation tests in an atmosphere of pure oxygen at a pressure of 300 kPa. The absorbent temperature was maintained at 60℃ during the oxidative degradation test, and the amine retention rate of each absorbent was obtained. The results are as follows: Figure 5 As shown.

[0092] Comparative Examples 3 and 4 show that, under conditions of oxygen oxidation of organic amines alone, different types of iodine-containing inorganic salts all exhibited superior effects in inhibiting the oxidative degradation of organic amines. Figure 5 It can be seen that when 1 mM iron ions are present in the absorbent, the iron ions catalyze the generation of free radicals, thereby accelerating the oxidation of amines. At this point, the addition of iodine has only a weak effect; after 120 h, the amine retention rate is only 29.2%. This may be largely related to the solubility of iron in different amine solutions. In a 30 wt% MEA aqueous solution with carbon dioxide supporting 0.4 mol CO2 / mol amine, the solubility of iron at 60°C is approximately 5 mg / L. However, a 30 wt% DETA aqueous solution has an iron solubility exceeding 120 mg / L under the same conditions. Therefore, in practical applications, chain polyamine solutions containing a large amount of dissolved iron have a strong catalytic effect on oxidation. Besides its rapid catalytic oxidation, some iron may react with iodine-containing inorganic salts to generate iodine molecules, thus consuming available iodides. Furthermore, the oxidation rates and mechanisms of different amines may also contribute to this phenomenon. Chain polyamines have more sites that can be attacked by active free radicals, making them inherently more susceptible to oxidation. Dissolved iron ions may cause electron transfer processes to become more intense, making certain reactions more likely to occur, and these free radicals may not be easily neutralized by iodine. When iron accumulates in the absorbent due to equipment corrosion, iodine-containing inorganic salts will gradually become ineffective.

[0093] Comparative Example 6

[0094] This comparative example provides an amine absorbent composed of the following components: DETA, NaI, ethylenediaminetetraacetic acid (EDTA), and water, wherein the content of DETA is 30 wt%, the content of NaI is 100 mmol / kg, and the content of EDTA is 10 mmol / kg. The content of the inhibitor in the absorbent is based on the weight of a 30 wt% DETA aqueous solution.

[0095] The preparation method of this amine absorbent includes the following steps: mixing DETA and water to obtain an amine solution; adding NaI and EDTA to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed, thereby obtaining the amine absorbent.

[0096] Comparative Example 7

[0097] This comparative example provides an amine absorbent composed of the following components: DETA, NaI, 1,3-propanediaminetetraacetic acid (PDTA), and water, wherein the content of DETA is 30 wt%, the content of NaI is 100 mmol / kg, and the content of PDTA is 10 mmol / kg. The content of the inhibitor in the absorbent is based on the weight of a 30 wt% DETA aqueous solution.

[0098] The preparation method of this amine absorbent includes the following steps: mixing DETA and water to obtain an amine solution; adding NaI and PDTA to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed to obtain the amine absorbent.

[0099] Example 1

[0100] This embodiment provides an amine absorbent composed of the following components: DETA, NaI, hydroxyethylidene diphosphonic acid (HEDP), and water. The DETA content is 30 wt%, the NaI content is 100 mmol / kg, and the HEDP content is 10 mmol / kg. The inhibitor content in the absorbent is based on the weight of a 30 wt% DETA aqueous solution.

[0101] The preparation method of this amine absorbent includes the following steps: mixing DETA and water to obtain an amine solution; adding NaI and HEDP to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed to obtain the amine absorbent.

[0102] Example 2

[0103] This embodiment provides an amine absorbent composed of the following components: DETA, NaI, diethylenetriaminepentamethylenephosphonic acid (DTPMPA), and water. The DETA content is 30 wt%, the NaI content is 100 mmol / kg, and the DTPMPA content is 10 mmol / kg. The inhibitor content in the absorbent is based on the weight of a 30 wt% DETA aqueous solution.

[0104] The preparation method of this amine absorbent includes the following steps: mixing DETA and water to obtain an amine solution; adding NaI and DTPMPA to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed, thereby obtaining the amine absorbent.

[0105] The molecular structures of the metal ion chelating agents used in Comparative Examples 6 and 7 and Examples 1 and 2 are shown in Table 1.

[0106] Table 1. Molecular structures of four metal ion chelating agents

[0107] The absorbents of Comparative Examples 6 and 7 and Examples 1 and 2 were each loaded with 1.2 mol CO2 / mol amine. Furthermore, 1 mM Fe was added to each of these absorbents. 3+ Then, these absorbents were subjected to oxidative degradation tests in an atmosphere of pure oxygen at a pressure of 300 kPa. The absorbent temperature was maintained at 60℃ during the oxidative degradation test, and the amine retention rate of each absorbent was obtained. The results are as follows: Figure 6 As shown.

[0108] As can be seen from Comparative Example 5 above, under iron-containing conditions, the oxidative degradation inhibition effect of iodine-containing inorganic salts is greatly weakened. Comparative Examples 6 and 7 and Examples 1 and 2 further added different metal ion chelating agents to the basis of iodine-containing inorganic salts, and inhibited the oxidative degradation of chain polyamines through the synergistic effect of iodine-containing inorganic salts and metal ion chelating agents.

[0109] Depend on Figure 6 It can be seen that the control group without the addition of inhibitors (i.e., 30 wt% DETA aqueous solution) degraded rapidly, with the amine retention rate dropping to below 20% within 30 h and stabilizing at only 8.7% by 120 h.

[0110] In Comparative Examples 6 and 7, EDTA and PDTA mainly formed chelates with iron ions through multi-site coordination of the amino and carboxylic acid groups. In Comparative Example 6, the addition of 100 mmol / kg NaI and 10 mmol / kg EDTA as inhibitors slowed down amine oxidation, retaining 83.5% of the amine after 120 hours. In Comparative Example 7, the addition of PDTA as a chelating agent to the absorbent only produced a moderate inhibitory effect, with a final amine retention rate of 13.5%, which was not improved compared to the amine retention rate (29.2%) of the absorbent with only 100 mmol / kg NaI in the presence of iron ions. This may be because PDTA has limited chelating efficiency for metal ions under experimental conditions, or it may interfere with the iodine inhibition mechanism.

[0111] In Examples 1 and 2, after using DTPMPA and HEDP respectively, the amine retention rates of the absorbents reached 102.6% and 100.1% respectively, achieving complete inhibition of the oxidative degradation of chain polyamines.

[0112] It can be seen that not all metal ion chelating agents can effectively inhibit the oxidative degradation of chain polyamines. The phosphate chelating agents used in Examples 1 and 2 of this invention, compared with the carboxylic acid chelating agents in Comparative Examples 6 and 7, can better exert their synergistic effect with iodine-containing inorganic salts, thereby achieving excellent inhibition of the oxidative degradation of chain polyamines.

[0113] In addition, oxidative degradation tests were performed on 30 wt% DETA aqueous solution (i.e., without inhibitor), 30 wt% DETA aqueous solution containing 100 mmol / kg NaI, 30 wt% DETA aqueous solution containing 10 mmol / kg EDTA, 30 wt% DETA aqueous solution containing 10 mmol / kg PDTA, 30 wt% DETA aqueous solution containing 10 mmol / kg HEDP, 30 wt% DETA aqueous solution containing 10 mmol / kg DTPMPA, and the absorbents of Comparative Examples 6 and 7 and Examples 1 and 2. These absorbents each carried 1.2 mol CO2 / mol amine. Furthermore, 1 mM Fe was added to each of these absorbents. 3+ Then, these absorbents were subjected to oxidative degradation tests in an atmosphere of pure oxygen at a pressure of 300 kPa. The absorbent temperature was maintained at 60℃ during the oxidative degradation test, and the amine retention rate of each absorbent was obtained. The results are as follows: Figure 7 As shown.

[0114] Figure 7 The display shows the amine retention rate of the above absorbents after 120 hours of oxidative degradation. It can be seen that, except for PDTA, the combinations of the other three metal ion chelating agents with iodine-containing inorganic salts can achieve better inhibition of organic amine oxidative degradation than adding iodine-containing inorganic salts or metal ion chelating agents alone. Among them, the phosphoric acid chelating agents used in Examples 1 and 2 of this invention exhibit the best synergistic effect with iodine-containing inorganic salts in inhibiting oxidative degradation, achieving 100% inhibition of the degradation of highly oxidized chain polyamines even under prolonged contact with oxygen and in the presence of iron ions. This indicates that there is a synergistic effect between the iodide as a free radical scavenger and the phosphoric acid chelating agent that chelates and catalyzes metal ions, and the inhibitors of this invention can significantly improve the oxidative stability of chain polyamines during long-term carbon dioxide capture operations.

[0115] In addition, the absorption performance of the amine absorbent of Example 1 and the 30 wt% DETA aqueous solution without inhibitor were tested. Furthermore, the desorption performance of the amine absorbent of Example 1 and the 30 wt% DETA aqueous solution without inhibitor after absorption saturation was tested, as well as the desorption performance of the 30 wt% DETA aqueous solution without inhibitor after absorption saturation with inhibitor added at the amount specified in Example 1 was tested. The results are as follows: Figure 8 and Figure 9As shown, the CO2 loading in the absorbent was tested using a conventional acid-base titration method. An appropriate amount of sample was taken, sulfuric acid was added, and the volume of CO2 released represented the CO2 loading. It can be seen that whether or not an inhibitor is added to the fresh solution before absorption does not affect the absorption performance of the organic amine solution. Regardless of whether the inhibitor is added before absorption or after absorption saturation, the desorption performance of the organic amine solution is similar to that of the original organic amine solution. Measurements of the carbon dioxide loading of the organic amine solution after absorption and desorption show that the addition of an inhibitor has almost no effect. Therefore, the addition of an inhibitor in this embodiment of the invention does not affect the original carbon dioxide capture performance of the amine absorbent.

[0116] Example 3

[0117] This embodiment provides an amine absorbent composed of the following components: AEEA, NaI, hydroxyethylidene diphosphonic acid (HEDP), and water. The content of AEEA is 30 wt%, the content of NaI is 100 mmol / kg, and the content of HEDP is 10 mmol / kg. The content of the inhibitor in the absorbent is based on the weight of a 30 wt% aqueous solution of AEEA.

[0118] The preparation method of this amine absorbent includes the following steps: mixing AEEA and water to obtain an amine solution; adding NaI and HEDP to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed to obtain the amine absorbent.

[0119] Figure 10 The results showed that the inhibitor formulation could effectively inhibit AEEA oxidation, with approximately 97% of AEEA remaining after 124 h.

[0120] Example 4

[0121] This embodiment provides an amine absorbent composed of the following components: TEPA, NaI, hydroxyethylidene diphosphonic acid (HEDP), and water. The TEPA content is 30 wt%, the NaI content is 100 mmol / kg, and the HEDP content is 10 mmol / kg. The inhibitor content in the absorbent is based on the weight of a 30 wt% TEPA aqueous solution.

[0122] The preparation method of this amine absorbent includes the following steps: mixing TEPA and water to obtain an amine solution; adding NaI and HEDP to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed to obtain the amine absorbent.

[0123] Because TEPA has a large molecular weight, it cannot be detected by GC testing. Therefore, acid-base titration is used to measure alkalinity to represent its oxidation rate. It should be noted that alkalinity indicates the concentration of amino groups. Some degradation products still contain amino groups, so the alkalinity test result is higher than the retention rate of TEPA amine molecules. Figure 11 The results showed that the inhibitor formulation could effectively inhibit TEPA oxidation, and the TEPA alkalinity remained at approximately 100% after 141 h.

[0124] Example 5

[0125] This embodiment provides an amine absorbent composed of the following components: TEPA, NaI, diethylenetriaminepentamethylenephosphonic acid (DTPMPA), and water. The TEPA content is 30 wt%, the NaI content is 100 mmol / kg, and the DTPMPA content is 10 mmol / kg. The inhibitor content in the absorbent is based on the weight of a 30 wt% TEPA aqueous solution.

[0126] The preparation method of this amine absorbent includes the following steps: mixing TEPA and water to obtain an amine solution; adding NaI and DTPMPA to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed to obtain the amine absorbent.

[0127] Figure 12 The results showed that the inhibitor formulation could effectively inhibit TEPA oxidation, and the TEPA alkalinity remained at approximately 99% after 141 h.

[0128] Example 6

[0129] This embodiment provides an amine absorbent composed of the following components: DETA, NaI, hydroxyethylidene diphosphonic acid (HEDP), and water. The DETA content is 30 wt%, the NaI content is 300 mmol / kg, and the HEDP content is 20 mmol / kg. The inhibitor content in the absorbent is based on the weight of a 30 wt% DETA aqueous solution.

[0130] The preparation method of this amine absorbent includes the following steps: mixing DETA and water to obtain an amine solution; adding NaI and HEDP to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed to obtain the amine absorbent.

[0131] Figure 13 The results showed that the inhibitor formulation could effectively inhibit DETA oxidation, with approximately 100% of DETA remaining after 124 h.

[0132] Example 7

[0133] This embodiment provides an amine absorbent composed of the following components: DETA, LiI, diethylenetriaminepentamethylenephosphonic acid (DTPMPA), and water. The content of DETA is 30 wt%, the content of LiI is 100 mmol / kg, and the content of DTPMPA is 20 mmol / kg. The content of the inhibitor in the absorbent is based on the weight of a 30 wt% DETA aqueous solution.

[0134] The preparation method of this amine absorbent includes the following steps: mixing DETA and water to obtain an amine solution; adding LiI and DTPMPA to the amine solution and stirring at 30°C to ensure that the inhibitor is fully dissolved and dispersed to obtain the amine absorbent.

[0135] Figure 14 The results showed that the inhibitor formulation could effectively inhibit DETA oxidation, with approximately 93% of DETA remaining after 141 h.

[0136] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An inhibitor for inhibiting the oxidative degradation of amine absorbents, comprising a combination of iodide and metal ion chelating agent, wherein the molar ratio of the iodide to the metal ion chelating agent is (80-300):(5-20).

2. The inhibitor for inhibiting the oxidative degradation of amine absorbents according to claim 1, wherein, The iodide is an iodine-containing inorganic salt; And / or, the iodide includes one or more of potassium iodide, sodium iodide, lithium iodide, and ammonium iodide.

3. The inhibitor for inhibiting the oxidative degradation of amine absorbents according to claim 1, wherein, The metal ion chelating agent is a phosphate chelating agent; And / or, the metal ion chelating agent includes one or more of hydroxyethylidene diphosphonic acid, diethylenetriaminepentamethylidene phosphonic acid, aminotrimethylidene phosphonic acid, ethylenediaminetetramethylidene phosphonic acid, hexamethylenediaminetetramethylidene phosphonic acid, and triethylenetetraaminehexamethylidene phosphonic acid.

4. The inhibitor for inhibiting the oxidative degradation of amine absorbents according to claim 1, wherein, The molar ratio of the iodide to the metal ion chelating agent is (80-300):(8-12).

5. The use of the inhibitor for inhibiting the oxidative degradation of amine absorbents according to any one of claims 1-4 in amine absorbents.

6. The application according to claim 5, wherein the amine absorbent contains an organic amine, the organic amine comprising one or more of chain polyamines, chain monoamines, cyclic amines and sterically hindered amines; Preferably, the organic amine comprises a chain polyamine.

7. The application according to claim 5, wherein the amine absorbent is an amine absorbent for capturing CO2 gas; And / or, the amine absorbent is an amine absorbent for capturing CO2-containing gases emitted from one or more emission sources, such as coal-fired power plants, gas-fired power plants, oil refineries, steel mills, and cement plants.

8. An amine absorbent, comprising: The invention comprises a chain polyamine, an inhibitor for inhibiting the oxidative degradation of amine absorbents as described in any one of claims 1-4, and a solvent; wherein the chain polyamine is present in an amount of 20-40 wt%, the inhibitor for inhibiting the oxidative degradation of amine absorbents contains 80-300 mmol / kg of iodide, and the inhibitor for inhibiting the oxidative degradation of amine absorbents contains 5-20 mmol / kg of metal ion chelating agent.

9. The amine absorbent according to claim 8, wherein, The content of the metal ion chelating agent is 8-12 mmol / kg.

10. The amine absorbent according to claim 8, wherein, The chain polyamine is a chain polyamine containing primary amine groups and / or secondary amine groups; And / or, the chain polyamine includes one or more of ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, diethylenetriamine, hydroxyethylethylenediamine, and tetraethylenepentamine.

11. The amine absorbent according to claim 8, wherein, The solvent is water.

12. The application of the amine absorbent according to any one of claims 8-11 in carbon dioxide capture.

13. The application according to claim 12, wherein, The application includes the following steps: contacting a gas mixture containing carbon dioxide with the amine absorbent to capture carbon dioxide; and desorbing the amine absorbent after capturing carbon dioxide to obtain a regenerated amine absorbent.

14. The application according to claim 13, wherein, The contact between the gas mixture containing carbon dioxide and the amine absorbent is carried out in an absorption tower, the temperature of the amine absorbent entering the absorption tower is 20-60°C, and the pressure at the bottom of the absorption tower is 0-20 kPa. And / or, the desorption of the amine absorbent after capturing carbon dioxide is carried out in a regeneration tower at a desorption temperature of 80-150°C and a top pressure of 0-400 kPa. And / or, the gas mixture containing carbon dioxide originates from one or more emission sources, including coal-fired power plants, gas-fired power plants, oil refineries, steel mills, and cement plants.

Images