A complex inhibitor for inhibiting degradation of an amine absorbent in carbon dioxide capture

Abstract

The application discloses a composite inhibitor composed of a metal chelating agent and a free radical scavenger and application of the composite inhibitor to inhibition of degradation of an amine absorbent in CO2 capture, and belongs to the field of post-combustion CO2 capture. The composite inhibitor is composed of a metal chelating agent and a free radical scavenger, the metal chelating agent refers to diethylenetriamine penta(methylene phosphonic acid) (DTPMP) or diethylenetriamine pentaacetic acid (DTPA), and the free radical scavenger refers to potassium iodide (KI) or sodium thiosulfate (Na2S2O3). The mass fraction of the metal chelating agent in the composite inhibitor is 10-90%, and the mass fraction of the composite inhibitor added to the amine absorbent is 0.1-1.0%. The composite inhibitor can significantly inhibit degradation of an alcohol amine absorbent in the field of CO2 capture, and has the characteristics of strong inhibition effect, low price, good stability and high solubility. In addition, the synergistic inhibition effect between the metal chelating agent and the free radical scavenger in the composite inhibitor can greatly reduce the use amount of the composite inhibitor and reduce the cost of the inhibitor.

Description

Technical Field

[0001] This invention relates to the field of post-combustion CO2 capture, and more specifically to a composite inhibitor composed of a metal chelating agent and a free radical scavenger, and its application in inhibiting the degradation of amine absorbents during CO2 capture. Technical Background

[0002] CO2 capture, utilization, and storage (CCUS) technology is a major approach to achieving CO2 emission reduction and addressing global climate change. Common CO2 capture technologies include pre-combustion capture, oxy-fuel combustion, and post-combustion capture. Among these, post-combustion capture technology does not alter the combustion system, has the advantage of integrating desulfurization and denitrification processes, and is relatively mature. It is the most promising industrialization route for large-scale CO2 capture and achieving clean energy utilization.

[0003] Post-combustion CO2 capture technologies mainly include physical adsorption, membrane separation, and chemical solvent absorption. Chemical solvent absorption using amine absorbents has advantages such as high decarbonization efficiency, mature technology, relatively low cost, and suitability for retrofitting existing power plants, making it considered the most feasible technology currently. However, during CO2 separation, amine absorbents are prone to degradation due to the presence of O2 and the influence of high-temperature environments. Degradation leads to absorbent loss and a decrease in CO2 absorption capacity, requiring the system to be replenished periodically, increasing operating costs. Simultaneously, degradation products cause equipment corrosion, solution foaming, and other phenomena, reducing system lifespan, and volatile degradation products also cause environmental pollution. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing methods by proposing a composite inhibitor that can effectively suppress the degradation of amine absorbents. This composite inhibitor consists of a metal chelating agent and a free radical scavenger. The metal chelating agent chelates metal ions in the amine solution, thus neutralizing their catalytic effect on amine degradation. The free radical scavenger reacts with free radicals in the amine solution, reducing the number of free radicals in the solution and thereby inhibiting the degradation of the amine absorbent. The synergistic effect of the metal chelating agent and the free radical scavenger in inhibiting the degradation of the amine absorbent significantly improves the inhibitory effect, reduces the amount of inhibitor used, and lowers the cost of the inhibitor.

[0005] The technical solution adopted in this invention is:

[0006] A composite inhibitor for inhibiting the degradation of amine absorbents, comprising a metal chelating agent and a free radical scavenger, wherein the metal chelating agent is diethylenetriaminepentamethylenephosphonic acid (DTPMP) or diethyltriaminepentaacetic acid (DTPA), and the free radical scavenger is potassium iodide (KI) or sodium thiosulfate (Na2S2O3).

[0007] The amine absorbent refers to an alcohol amine absorbent used to capture CO2, with an alcohol amine mass fraction ranging from 20% to 60%.

[0008] The temperature at which the alkanolamine absorbent captures CO2 varies from 40 to 60°C.

[0009] The mass fraction of the chelating agent in the compound inhibitor varies from 10% to 90%.

[0010] The mass fraction of the compound inhibitor in the amine absorbent varies from 0.1% to 1%.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] 1. This invention proposes a composite inhibitor that can effectively inhibit amine degradation. This composite inhibitor has the characteristics of strong inhibition effect, low price, good stability and high solubility.

[0013] 2. In the composite inhibitor of the present invention, the chelating agent and the scavenging agent have a synergistic inhibitory effect on amine degradation. Compared with single amine degradation inhibitors, the synergistic inhibitory effect between the composite inhibitors can significantly reduce the amount of inhibitor used, thus solving the problems of amine degradation and increased operating costs caused by degradation from the source. Attached Figure Description

[0014] Figure 1 The structural diagrams of 1AP, DTPMP, DTPA, Na2S2O3 and KI in Examples 1-6 and Comparative Examples 2-6 of this invention are shown.

[0015] Figure 2 These are schematic diagrams of the oxidative degradation devices used in Examples 1-6 and Comparative Examples 1-6 of the present invention;

[0016] Figure 3 The external standard curves are those used in Examples 1-6 and Comparative Examples 1-6 of this invention;

[0017] Figure 4 The concentration changes of 1AP during the degradation process in Examples 1-6 and Comparative Examples 1-6 of the present invention are shown. Detailed Implementation

[0018] The following detailed description of the composite inhibitor and its application, with reference to specific embodiments, illustrates this invention. Clearly, the described embodiments are merely a subset of embodiments of the invention, and not all embodiments. Other embodiments readily obtainable based on the given embodiments also fall within the scope of protection of this invention.

[0019] Example 1

[0020] Using DTPMP+KI as a complex inhibitor, the structural formula of this complex inhibitor is shown in the attached figure. Figure 1As shown in the attached diagram, an oxidative degradation experiment of 1-amino-2-propanol (1AP) was conducted. Figure 2 As shown.

[0021] (1) Preparation of amine absorbent

[0022] Prepare a 5.0 mol / L 1AP absorbent using a volumetric flask. Continuously bubble CO2 into the prepared amine absorbent and test the CO2 loading of the absorbent, aiming to achieve a final CO2 loading of 0.4 mol / mol.

[0023] (2) Conducting oxidative degradation experiments

[0024] 200 mL of amine absorbent, 0.5 mmol / L FeSO4, and 1.0 wt% of a combined inhibitor (DTPMP + KI) were added to a three-necked flask. The flask was placed in a water bath, and the reaction temperature was maintained at 60 °C using the water bath. The gas composition of O2 and CO2 was controlled to be 98% O2 + 2% CO2 using a mass flow controller (MFC). The mixed gas was introduced into the three-necked flask through a rotor flow meter at a flow rate of 20 mL / min. A serpentine condenser was placed above the three-necked flask to condense and reflux the evaporated moisture. The oxidative degradation experiment was conducted for 14 days, and samples were taken for analysis on days 1, 2, 4, 7, and 14.

[0025] (3) Amine concentration test

[0026] The amine absorbent sample was diluted 10,000 times with deionized water, and the diluted sample was injected into a cation exchange chromatography system for analysis. The cation exchange chromatography system (Shine CIC-D100 system) was equipped with an SH-CC-9 analytical column (4.6 × 250 mm), an SH-G-1 guard column (4 × 50 mm), conductivity detection, and an SHY-C-5 suppressor. The eluent was a 3.0 mmol / L methanesulfonic acid solution. Standard amine solutions with concentrations ranging from 1 to 50 mg / L were prepared to obtain external standard curves, as shown in the attached figure. Figure 3 As shown. The formula for calculating amine loss due to degradation is as follows:

[0027]

[0028] In the formula:

[0029] C loss - 1AP loss due to degradation;

[0030] Peak area of ​​initial 1AP before A0-degradation experiment;

[0031] A x - The peak area of ​​1AP in the degradation sample;

[0032] The intercept value of the linear regression equation when the b-external standard curve is established;

[0033] The slope of the linear regression equation when the a-external standard curve is established;

[0034] D - Dilution factor;

[0035] The relative molecular mass of M-1AP.

[0036] Example 2

[0037] Using DTPMP+Na2S2O3 as a complex inhibitor, the structural formula of this complex inhibitor is shown in the attached figure. Figure 1 As shown, an 1AP oxidative degradation experiment was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 0.1 wt% composite inhibitor (DTPMP + Na2S2O3) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0038] Example 3

[0039] Using DTPMP+Na2S2O3 as a complex inhibitor, the structural formula of this complex inhibitor is shown in the attached figure. Figure 1 As shown, an 1AP oxidative degradation experiment was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 0.2 wt% composite inhibitor (DTPMP + Na2S2O3) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0040] Example 4

[0041] Using DTPMP+Na2S2O3 as a complex inhibitor, the structural formula of this complex inhibitor is shown in the attached figure. Figure 1 As shown, an 1AP oxidative degradation experiment was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 1.0% composite inhibitor (DTPMP+Na2S2O3) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0042] Example 5

[0043] Using DTPA+Na2S2O3 as a complex inhibitor, the structural formula of this complex inhibitor is shown in the attached figure. Figure 1 As shown, an oxidative degradation experiment of 1AP was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 1.0% composite inhibitor (DTPA+Na2S2O3) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0044] Example 6

[0045] Using DTPA+KI as a complex inhibitor, the structural formula of this complex inhibitor is shown in the attached figure. Figure 1 As shown, an oxidative degradation experiment was carried out using 1AP. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 1.0% composite inhibitor (DTPA+KI) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0046] Comparative Example 1

[0047] The 1AP oxidative degradation experiment was carried out without the addition of a compound inhibitor. 200 mL of amine absorbent and 0.5 mmol / L FeSO4 were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0048] Comparative Example 2

[0049] Using DTPMP as a single inhibitor, the structural formula of this combination inhibitor is shown in the attached figure. Figure 1 As shown, an 1AP oxidative degradation experiment was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 0.1% single inhibitor (DTPMP) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0050] Comparative Example 3

[0051] Using DTPMP as a single inhibitor, the structural formula of this combination inhibitor is shown in the attached figure. Figure 1 As shown, an 1AP oxidative degradation experiment was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 1.0% single inhibitor (DTPMP) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0052] Comparative Example 4

[0053] Using DTPA as a single inhibitor, the structural formula of this compound inhibitor is shown in the attached figure. Figure 1 As shown, an oxidative degradation experiment was carried out using 1AP. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 1.0% single inhibitor (DTPA) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0054] Comparative Example 5

[0055] Using KI as a single inhibitor, the structural formula of this complex inhibitor is shown in the attached figure. Figure 1As shown, an 1AP oxidative degradation experiment was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 1.0% single inhibitor (KI) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0056] Comparative Example 6

[0057] Using Na2S2O3 as a single inhibitor, the structural formula of this composite inhibitor is shown in the attached figure. Figure 1 As shown, an 1AP oxidative degradation experiment was carried out. 200 mL of amine absorbent, 0.5 mmol / L FeSO4 and 1.0% single inhibitor (Na2S2O3) were added to a three-necked flask. Other degradation experimental conditions and amine concentration test methods were the same as in Example 1.

[0058] The changes in 1AP concentration after adding different inhibitors are shown in the attached figure. Figure 4 As shown in Table 1, the data indicate that the addition of the composite inhibitor significantly inhibited the oxidative degradation of 1AP, reducing the 1AP loss from 47.0% to less than 7.0%. Comparing Example 1 with Comparative Examples 3 and 5, the addition of the composite inhibitor at the same concentration showed a better inhibitory effect than the single inhibitor, reducing the 1AP loss from 10.8% (addition of 1.0% DTPMP) and 26.3% (addition of 1.0% KI) to 6.3% (addition of 1.0% DTPMP + KI). The same conclusion was reached when comparing Examples 4, 5, and 6 with Comparative Examples 3, 4, 5, and 6. The experimental results of Comparative Example 2 showed that the inhibitory effect of 0.1% DTPMP was weak, only reducing the 1AP loss from 47.0% to 45.3%. However, the addition of 0.1% composite inhibitor (DTPMP + Na2S2O3, Example 2) showed a significant inhibitory effect, reducing the 1AP loss from 47.0% to 6.1%. The above results indicate that the metal chelator and free radical scavenger in the composite inhibitor can synergistically inhibit the oxidative degradation of 1AP, with a significantly improved inhibition efficiency compared to the single inhibitor. A very small amount of composite inhibitor (0.1%) can achieve an inhibitory strength exceeding that of a larger amount of single inhibitor (1.0%).

[0059] Table 1: Effects of adding different inhibitors on the change in 1AP concentration during degradation.

[0060]

[0061] a The mass ratio of metal chelating agent to free radical scavenger in the compound inhibitor is 1:1.

[0062] The composite inhibitor of the present invention can significantly inhibit the degradation of amine absorbents during CO2 capture, reduce amine loss caused by degradation, and the composite inhibitor exhibits better inhibitory effect than the single inhibitor. The synergistic inhibitory effect between the metal chelator and the free radical scavenger can significantly reduce the amount of composite inhibitor used and reduce the cost of the inhibitor.

[0063] The above-disclosed embodiments are merely a few specific examples of the present invention. Those skilled in the art can make various modifications and alterations to the embodiments of the present invention without departing from the spirit and scope of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be proposed by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. The application of a composite inhibitor in inhibiting the degradation of amine absorbents during CO2 capture, characterized in that, The composite inhibitor consists of a metal chelating agent and a free radical scavenger: the metal chelating agent is diethylenetriaminepentamethylenephosphonic acid (DTPMP) or diethyltriaminepentaacetic acid (DTPA), and the free radical scavenger is potassium iodide (KI) or sodium thiosulfate (Na2S2O3); the mass ratio of the metal chelating agent to the free radical scavenger in the composite inhibitor is 1:1, and the amount of the composite inhibitor added to the amine absorbent is 0.1%–1.0%.

2. The application of the composite inhibitor according to claim 1 in inhibiting the degradation of amine absorbents in CO2 capture, characterized in that, This composite inhibitor is used in the field of CO2 capture to inhibit the degradation of alcohol amine absorbents, with the mass fraction of the alcohol amine absorbent being 20-60%.

3. The application of the composite inhibitor according to claim 1 in inhibiting the degradation of amine absorbents in CO2 capture, characterized in that, The temperature for capturing CO2 with amine absorbents is 40-60℃.

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