Method for measuring CO2 load in organic amine absorption liquid

Abstract

The invention discloses a method for measuring CO2 load in organic amine absorption liquid, and belongs to the technical field of CO2 capture. The method comprises the following steps: weighing an organic amine absorption liquid sample, putting the organic amine absorption liquid sample into a conical flask, adding a methyl orange indicator, putting the conical flask into an acidolysis gas measuring device, sealing, titrating with an acid standard solution to a titration end point, and continuously adding excessive acid standard solution until the liquid level of a gas measuring pipe in the acidolysis gas measuring device does not change; and moving the water level bottle to enable the liquid level of the water level bottle to be flush with the liquid level of the gas measuring pipe, and reading the liquid level difference value before and after acidolysis of the gas measuring pipe to calculate the CO2 load of the organic amine absorption liquid. According to the method, the CO2 load is measured through weight method sampling and acidolysis, the amine value of the organic amine absorption liquid can be measured at the same time, the tedious operation that the density needs to be measured at any time in a volumetric method sampling method is effectively eliminated, errors caused by thermal expansion and cold contraction phenomena are effectively eliminated, and the method has the advantages of being simple, rapid and accurate.

Description

Technical Field

[0001] This invention relates to the field of CO2 capture technology, and in particular to a method for determining the CO2 load in an organic amine absorbent. Background Technology

[0002] CO2 capture, utilization, and storage (CCUS) is a process that separates CO2 from industrial processes, energy use, or the atmosphere for direct utilization or injection into geological formations, resulting in permanent CO2 emission reduction. CO2 capture is the foundation of CCUS implementation. Currently, the CO2 capture technology that has achieved industrial application is chemical absorption, among which organic amine solution absorption is the most widely researched and applied method.

[0003] The organic amine solution absorption method for CO2 capture involves a chemical reaction between an organic amine solution and CO2 in a mixed gas within a low-temperature absorption unit. This reaction produces carbonaceous compounds such as carbamates, bicarbonates, and carbonates, forming a rich absorbent solution. This rich solution is then heated in a high-temperature desorption unit to release the absorbed CO2, while simultaneously regenerating the organic amine solution, creating a lean absorbent solution. This lean solution is then recycled back into the absorption tower, thus achieving the separation of CO2 from other gases in the mixed gas. The CO2 load of the organic amine in the rich and lean absorbent solutions is an important indicator for evaluating the performance of the organic amine solution.

[0004] Currently, methods for determining CO2 load in organic amine absorbents include infrared absorption, calorimetry, and acid hydrolysis gas chromatography. Among these, acid hydrolysis gas chromatography is widely used due to its simplicity, convenience, and speed (e.g., ①Song Zhou, Yunlong Zhu, Hongyuan Xi, Ze Hao, Zhitao Han, Chengqi Sun, Research on CO2 capture performance and reaction mechanism using newly tetraethylenepentamine (TEPA) + monoethanolamine (MEA) mixed absorbent for onboard application, Chemical Engineering Journal, Volume 485, 2024, 149790, ISSN 1385-8947. ②Liju Bai, Dongfang Zhao, Xinkai Zhong, Shoulong Dong, Helei Liu, Comprehensive technical analysis of CO2 absorption into a promising blended amine of DEEA-HMDA, Chemical Engineering Science, Volume 280, 2023, 119025, ISSN 1385-8947). 0009-2509.③ Chen Jie, Tang Jianfeng, Hua Yihuai, et al. Performance study of mixed amine liquid for CO2 removal from natural gas [J]. Acta Petrolei Sinica (Petroleum Processing), 2015, 31(04):904-911.

[0005] The principle of the acidolysis gas measurement method is to add excess acid to the organic amine absorbent loaded with CO2, causing the carbamates, bicarbonates, and carbonates in the absorbent to decompose and release CO2. The CO2 load of the organic amine solution is calculated by measuring the volume of CO2 released using a gas measuring device.

[0006] The specific operating method is as follows: Take a certain volume of organic amine absorption liquid sample V t Add as attached Figure 1 In the acidolysis apparatus shown, excess acid is added to the conical flask through an acid burette to fully decompose and release CO2 from the sample. The difference in readings before and after the gas measuring tube is measured, and then the amount of CO2 obtained from the acidolysis is calculated using the formula shown in Equation VII below:

[0007]

[0008] in, The value represents the amount of CO2 released from the sample, in mol. ΔV is the difference in liquid level readings in the gas measuring tube before and after the addition of acid, in mL. a The volume of acid added is in mL. T is the room temperature on the day of the measurement, in K.

[0009] Then, divide the amount of CO2 released from the sample by the amount of organic amine absorbent contained in the sample, and calculate the organic amine load using the formula shown in Equation VIII:

[0010]

[0011] in, V represents the amount of CO2 released from the sample, expressed in moles. t N represents the volume of the sample taken, in mL. amine The molar concentration of the prepared organic amine solution is expressed in mol / L, N. amine The result is obtained from formula IX:

[0012]

[0013] Where, m amine M represents the mass of the amine in the prepared organic amine solution, in grams; amine m is the molar molecular weight of the amine, in g / mol. solution The mass of the prepared solution is expressed in grams (g); ρ solution The density of the prepared solution is expressed in g / mL.

[0014] Volumetric sampling has the following drawbacks in practical operation:

[0015] (1) Due to the phenomenon of thermal expansion and contraction, the sampling temperature varies during the volumetric method, such as 40-50℃ for absorption and 90-130℃ for desorption. If the acid hydrolysis gas chromatography test cannot be performed in time after sampling, especially when the sampling time interval is short, the actual titration temperature of the acid hydrolysis gas chromatography test will be different from the sampling temperature, resulting in a difference in the sampled volume. Consequently, the test results will fluctuate with the temperature during the test, leading to inaccurate test results.

[0016] (2) Due to the different room temperature every day, there is a time difference between sampling and testing. The actual test temperature is between the sampling temperature and the room temperature. As a result, the volume of the sample taken during acid titration will fluctuate with the temperature, which will cause errors in the test results.

[0017] (3) n in the organic amine loading formula calculated from Equation VIII amineIt is assumed that the concentration remains constant during the absorption process. However, after the organic amine absorbs CO2, its density will change with the CO2 load and temperature. The molar mass concentration of the organic amine will also gradually decrease, and the calculated results will deviate from the actual data.

[0018] (4) To ensure the accuracy of the volumetric sampling method, the volumetric sampling method requires continuous measurement of the real-time density ρ of the sample taken. solution Calculating the mass of organic amines in the sample is extremely tedious and complicated.

[0019] Therefore, there is an urgent need to develop a simple and efficient method for detecting CO2 load. Summary of the Invention

[0020] To address the technical problem of errors in volumetric sampling methods used in existing CO2 load testing techniques for organic amine absorbents, this invention provides a method for determining the CO2 load in organic amine absorbents. In particular, it provides a CO2 load measurement method using gravimetric sampling, which, because gravimetric sampling is unaffected by temperature, density, or testing time, can accurately reflect the actual CO2 load.

[0021] The purpose of this invention is to provide a method for determining the CO2 load in an organic amine absorbent, comprising the following steps:

[0022] (1) Add the sealing liquid to the water level bottle of the acidolysis gas measuring device, rotate the three-way valve to the three-way position, raise the position of the water level bottle, so that the liquid level of the sealing liquid in the gas measuring column reaches the top mark.

[0023] (2) Place the acid standard solution into the acid burette of the acidolysis gas measuring device and record the initial liquid level.

[0024] (2) Weigh out the organic amine absorbent sample containing carbon dioxide gas by mass, place it in an Erlenmeyer flask, add deionized water and methyl orange indicator; then place the Erlenmeyer flask in the acidolysis gas measuring device and seal it, adjust the height of the water level bottle to be level with the liquid surface of the gas measuring tube, and record the scale V1 of the gas measuring tube.

[0025] (3) Add the acid standard solution to the titration endpoint and record the graduations on the acid burette.

[0026] (4) Continue to add excess acid to fully release CO2 from the sample until the liquid level in the gas measuring tube stops changing, and record the graduations on the acid burette.

[0027] (5) Move the water level bottle up and down until the liquid level in the water level bottle is the same as the liquid level in the gas measuring tube. At this time, the gas pressure above the solution is the same as the external gas pressure. Record the scale V2 of the gas measuring tube.

[0028] (6) Calculate the total amount of CO2 released in the organic amine solution sample by acid decomposition. Total mass Then calculate the mass m of the organic amine solution in the sample. solution The amount of substance n of organic amines amine Finally, the CO2 load of the organic amine solution by mass and the CO2 load of the organic amine by mole were calculated.

[0029] Furthermore, the sealing solution is a saturated NaCl solution, and is acidified with 1% hydrochloric acid until the 0.1% methyl orange indicator turns red.

[0030] Furthermore, the total amount of CO2 released in the organic amine solution sample by acid decomposition was calculated. Total mass Calculate according to the formulas shown in Equation I and Equation II respectively:

[0031]

[0032] in, This represents the amount of CO2 released from the organic amine solution sample, expressed in mol. V2 represents the mass of CO2 released by the acid hydrolysis of the organic amine solution sample, in g; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level is equal to that in the water level bottle, in mL. t is the total volume of the acid standard solution added, in mL; t is the room temperature at the time of measurement, in °C.

[0033] Furthermore, the mass of the organic amine solution in the sample is calculated according to the formula shown in Equation III:

[0034]

[0035] Where, m solution The mass of the organic amine solution in the sample is the mass of the organic amine sample after removing the mass of the loaded CO2, in g; m0 is the mass of the organic amine sample weighed, in g. V2 is the total volume of the acid standard solution added, in mL; t is the room temperature at the time of measurement, in °C; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is equal, in mL.

[0036] Furthermore, the amount of organic amine in the organic amine solution of the sample is calculated according to the formula shown in Equation IV:

[0037]

[0038] Where, n amine The amount of organic amine in the sample taken is expressed in mol; Cacid The concentration of the acid standard solution is expressed in mol / L.

[0039] Furthermore, the CO2 load of the organic amine solution by mass is calculated as shown in Equation V:

[0040]

[0041] Where, α m CO2 loading of organic amine solution by mass, expressed in g CO2 / g solution; m0 represents the mass of CO2 released by the acid decomposition of the organic amine solution sample, in g; m0 represents the mass of the organic amine sample weighed, in g. V2 is the total volume of the acid standard solution added, in mL; t is the room temperature at the time of measurement, in °C; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is equal, in mL.

[0042] Furthermore, the calculation of the CO2 load of the organic amine solution, in molar terms, is shown in Equation VI:

[0043]

[0044] Where, α n CO2 loading of an organic amine solution by mole, expressed in mol CO2 / mol amine; V2 is the total volume of the acid standard solution added, in mL; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is the same, in mL; t is the room temperature at the time of measurement, in °C.

[0045] Furthermore, the organic amine includes, but is not limited to, one or more of ethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), diethylene glycolamine (DGA), diethanolamine (DEA), triethanolamine (TEA), N-methyldiethanolamine (MDEA), piperazine (PZ), ethylenediamine (EDA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA).

[0046] Furthermore, the acid in the acid standard solution is selected from hydrochloric acid and / or sulfuric acid.

[0047] The technical solution of the present invention has the following advantages compared with the prior art:

[0048] This invention employs a gravimetric sampling method, utilizing an acid-hydrolysis gas measuring device, to determine various parameters of the CO2 load in organic amine absorbents. It establishes a method for calculating the CO2 load in organic amine absorbents, eliminating errors caused by temperature fluctuations and variations in the viscosity of the organic amine solution during measurement. This improves the accuracy of the results and reduces testing errors. Compared to volumetric sampling, the gravimetric sampling method of this invention is simpler, faster, and unaffected by testing time intervals or temperature. Attached Figure Description

[0049] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0050] Figure 1 This is a schematic diagram of the acidolysis gas measurement device of the present invention. 1. Water level bottle; 2. Lifting iron stand; 3. Gas measuring tube; 4. Acid burette; 5. Conical flask; 6. Magnetic stirrer; 7. Magnetic stirring rotor. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0052] To illustrate the content of this invention, the organic amine absorbent solution is used as an example of monoethanolamine (MEA) and triethylenetetramine (TETA).

[0053] In the CO2 absorption experiment in the example: 100g of an organic amine aqueous solution with a mass concentration of 30% was added to a round-bottom flask placed in an oil bath. The oil bath temperature was controlled at 40°C. A mixed gas of CO2 and N2 with a CO2 volume fraction of 15% was introduced. The flow rate of the mixed gas was 1000mL / min, and the absorption time was 150min, resulting in a CO2-rich absorption solution.

[0054] In the embodiment, the CO2 desorption experiment method is as follows: The desorption bottle equipped with a reflux condenser is placed in an oil bath heater and heated to 120°C. The CO2-rich solution obtained from the absorption experiment is then placed into the desorption bottle and desorbed for 90 minutes to obtain the desorption-poor solution.

[0055] The specific steps for determining the CO2 load in the organic amine absorbent using the gravimetric method in this embodiment are as follows:

[0056] (1) Place the hydrochloric acid standard solution in the container as shown in the attached table. Figure 1 The initial liquid level was recorded in the acid burette of the acidolysis gas measuring device.

[0057] (2) Weigh 1.00g of organic amine absorption liquid sample and place it in a 250mL conical flask; add about 10mL of deionized water and 3-4 drops of methyl orange indicator. Then place the conical flask in the acidolysis gas measuring device and seal it. Adjust the height of the water level bottle to be level with the liquid surface of the gas measuring tube and record the scale of the gas measuring tube (V1, mL).

[0058] (3) Add hydrochloric acid standard solution to the titration endpoint and record the burette reading.

[0059] (4) Continue to add excess hydrochloric acid to fully release CO2 from the sample until the liquid level in the gas measuring tube no longer changes, and record the burette graduations.

[0060] (5) Move the water level bottle up and down until the liquid level in the water level bottle is level with the liquid level in the gas measuring tube. At this time, the gas pressure above the solution is the same as the outside gas pressure. Record the scale of the gas measuring tube (V2, mL).

[0061] (6) Calculate the total amount of substance and total mass of CO2 in the organic amine solution sample released by acid decomposition, using the formulas shown in Formula I and Formula II respectively:

[0062]

[0063]

[0064] in, This represents the amount of CO2 released from the sample, expressed in mol. V2 represents the mass of CO2 released by the acid hydrolysis of the sample, in g; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is equal, in mL. The total volume after deducting the added acid is expressed in mL; t is the room temperature at the time of measurement, expressed in °C.

[0065] (7) Based on the above calculation results, the mass of the organic amine solution in the sample is calculated according to the formula shown in Formula III:

[0066]

[0067] Where, m solution The mass of the organic amine solution in the sample (i.e., the mass of the sample after removing the loaded CO2) is in grams. m0 is the mass of the sample weighed, in grams. V2 is the total volume of the acid standard solution added, in mL; t is the room temperature at the time of measurement, in °C; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is equal, in mL.

[0068] (8) Based on the above calculation results, the amount of organic amine in the sample is calculated according to the formula shown in Formula IV:

[0069]

[0070] Where, n amine C represents the amount of organic amine in the sample, expressed in mol. acid The concentration of the acid standard solution is expressed in mol / L.

[0071] (9) Based on the above calculation results, the CO2 load of the organic amine solution by mass is calculated according to the formula shown in Equation V:

[0072]

[0073] Where, α m The CO2 load of the organic amine solution is expressed as g CO2 / g solution.

[0074] (10) Based on the above calculation results, the load of organic amines absorbing CO2, in molar terms, is calculated according to the formula shown in Equation VI:

[0075]

[0076] Where, α n The loading of organic amines on CO2 absorption, expressed in molar amounts, is expressed as mol CO2 / mol amine.

[0077] The specific method for determining the CO2 absorption load of organic amines using volumetric sampling is as follows:

[0078] (1) Take 1.0 mL of the sample, add it to the acid hydrolysis device, and then add 25 mL of standard acid solution to fully release the CO2 in the sample. Measure the difference in readings before and after the measurement, and then calculate the amount of CO2 obtained by acid hydrolysis using the formula shown in Equation VII:

[0079]

[0080] in, The value represents the amount of CO2 released from the sample, in mol. ΔV is the difference in liquid level readings in the gas measuring tube before and after the addition of acid, in mL. a The volume of acid added is in mL. t is the room temperature on the day of measurement, in K.

[0081] (2) Then, divide the amount of CO2 released from the sample by the amount of organic amine absorbent per milliliter of the prepared solution, and calculate the organic amine load using the formula shown in Equation VIII:

[0082]

[0083] in, V represents the amount of CO2 released from the sample, expressed in moles. t The volume of the sample taken is in mL. n(amine) is the amount of organic amine contained in each milliliter of the prepared solution, in mol / mL. n(amine) is calculated using formula IX:

[0084]

[0085] Where, m amine The mass of amine used to prepare the amine solution is expressed in grams; M amine m is the molar mass of the amine, in g / mol. solution The mass of the prepared solution is expressed in grams (g); ρ solution The density of the prepared solution is expressed in g / mL.

[0086] Example 1

[0087] This embodiment provides a gravimetric sampling method for determining CO2 load in MEA absorption experiments, as detailed below:

[0088] 100.00 g of a 30.0 wt% MEA aqueous solution was added to a round-bottom flask placed in an oil bath at 40 °C. A mixture of CO2 and N2 gas with a CO2 volume fraction of 15% was introduced at a flow rate of 1000 mL / min and a pressure of 0.1 MPa for 150 min, resulting in a CO2-rich absorbent solution. Four samples, approximately 10 g each, were taken and cooled to 5 °C, 10 °C, 20 °C, and 30 °C respectively in a cooling water bath. 1.00 g of each sample was then taken and placed in an acidolysis gas measuring device to test the CO2 content of the absorbent solution. The test results are shown in Table 1. The results indicate that the average CO2 load measured at different temperatures is relatively similar, with the maximum difference being less than 1.0 × 10⁻⁶. -3 mol CO2 / mol amine, indicating that the test results of gravimetric sampling are not affected by temperature.

[0089] Table 1. Determination of CO2 load in MEA absorption experiments by gravimetric sampling.

[0090]

[0091] Example 2

[0092] This embodiment provides a gravimetric sampling method for determining the CO2 load in a MEA desorption experiment, as detailed below:

[0093] The desorption flask with a reflux condenser was placed in an oil bath heater and heated to 130°C. The MEA-rich absorbent obtained in Example 1 was then placed into the desorption flask. Samples were taken every 30 minutes, and the CO2 load was measured using the acid-hydrolysis gas gaussing method. Desorption was considered complete when the CO2 load of the absorbent showed no significant change, resulting in a lean desorption solution. Six samples, approximately 10g each, were taken and cooled in a water bath to 90°C, 70°C, 50°C, 30°C, 20°C, and 10°C, respectively. 1.00g of each sample was then taken and placed in an acid-hydrolysis gas gaussing device to test the CO2 content of the absorbent. The test results are shown in Table 2. Table 2 shows that the average CO2 load measured at different temperatures was relatively similar, with the maximum difference being less than 1.0 × 10⁻⁶. -3 The results of gravimetric sampling are not affected by temperature, even when there are large differences in sample temperature.

[0094] Table 2. CO2 load in MEA desorption experiments determined by gravimetric sampling.

[0095]

[0096] Example 3

[0097] This embodiment provides a gravimetric sampling method for determining CO2 load in a TETA absorption experiment, as detailed below:

[0098] 100.00 g of a 30.0 wt% TETA aqueous solution was added to a round-bottom flask placed in an oil bath at 40 °C. A mixture of CO2 and N2 gas with a CO2 volume fraction of 15% was introduced at a flow rate of 1000 mL / min and a pressure of 0.1 MPa for 150 min, resulting in a CO2-rich absorbent solution. Four samples, approximately 10 g each, were taken and cooled to 5 °C, 10 °C, 20 °C, and 30 °C respectively in a cooling water bath. 1.00 g of each sample was then taken and placed in an acidolysis gas measuring device to test the CO2 content of the absorbent solution. The test results are shown in Table 3. The average CO2 load measured at different temperatures showed little difference, with the maximum difference being less than 1.0 × 10⁻⁶. -3 mol CO2 / mol amine, indicating that the test results of gravimetric sampling are not affected by temperature.

[0099] Table 3. CO2 load determination in TETA absorption experiments using gravimetric sampling.

[0100]

[0101] Example 4

[0102] This embodiment provides a gravimetric sampling method for determining CO2 load in a TETA desorption experiment.

[0103] The desorption flask with a reflux condenser was placed in an oil bath heater and heated to 130°C. The TETA-rich absorbent obtained in Example 3 was then added to the desorption flask. Samples were taken every 30 minutes, and the CO2 load was measured using the acid-hydrolysis gas gaussing method. Desorption was considered complete when the CO2 load of the absorbent showed no significant change, resulting in a lean desorption solution. Six samples, approximately 10g each, were taken and cooled in a water bath to 90°C, 70°C, 50°C, 30°C, 20°C, and 10°C, respectively. 1.00g of each sample was then taken and placed in an acid-hydrolysis gas gaussing device to test the CO2 content of the absorbent. The test results are shown in Table 4. The average CO2 load measured at different temperatures showed little difference, with the maximum difference being less than 1.0 × 10⁻⁶. -3 The results of gravimetric sampling are not affected by temperature, even when there are large differences in sample temperature.

[0104] Table 4. CO2 load determination in TETA desorption experiments using gravimetric sampling.

[0105]

[0106] Comparative Example 1

[0107] This comparative example provides a volumetric sampling method for determining CO2 load in MEA absorption experiments.

[0108] 100.00 g of a 30.0 wt% MEA aqueous solution was added to a round-bottom flask placed in an oil bath at 40 °C. A mixture of CO2 and N2 gas with a CO2 volume fraction of 15% was introduced at a flow rate of 1000 mL / min and a pressure of 0.1 MPa for 150 min, resulting in a CO2-rich absorbent solution. Four samples, approximately 10 g each, were taken and cooled to 5 °C, 10 °C, 20 °C, and 30 °C respectively in an ice-water bath. 1.0 mL of each sample was then placed in an acidolysis gas measuring device to test the CO2 content of the absorbent solution. The test results are shown in Table 5. The average CO2 load measured at the same temperature varied considerably, with the maximum difference exceeding 6.1 × 10⁻⁶. -2 The results of volumetric sampling (mol CO2 / mol amine) are significantly affected by temperature.

[0109] Table 5. CO2 load determination in MEA absorption experiments using volumetric sampling method.

[0110]

[0111] Comparative Example 2

[0112] This comparative example provides a volumetric sampling method for determining CO2 load in MEA desorption experiments, as shown below:

[0113] The desorption flask with a reflux condenser was placed in an oil bath heater and heated to 130°C. The MEA-rich absorbent obtained in Example 1 was then placed into the desorption flask. Samples were taken every 30 minutes, and the CO2 load was measured using the acid-hydrolysis gas chromatography method. Desorption was considered complete when the CO2 load of the absorbent showed no significant change, resulting in a lean desorption solution. Six samples, approximately 10g each, were taken and cooled in an ice-water bath to 90°C, 70°C, 50°C, 30°C, 20°C, and 10°C, respectively. 1.0mL of each sample was then placed in the acid-hydrolysis gas chromatography device to test the CO2 content of the absorbent. The test results are shown in Table 6. The average CO2 load measured at different temperatures varied considerably, with the maximum difference exceeding 5.7 × 10⁻⁶. -2 The results of volumetric sampling (mol CO2 / mol amine) are significantly affected by temperature.

[0114] Table 6. CO2 load determination in MEA desorption experiments using volumetric sampling method.

[0115]

[0116]

[0117] Comparative Example 3

[0118] This comparative example provides a volumetric sampling method for determining CO2 load in TETA absorption experiments, as shown below:

[0119] 100.00 g of a 30.0 wt% TETA aqueous solution was added to a round-bottom flask placed in an oil bath at 40 °C. A mixture of CO2 and N2 gas with a CO2 volume fraction of 15% was introduced at a flow rate of 1000 mL / min and a pressure of 0.1 MPa. Approximately 3 g samples were taken every 20 min, and the absorption time was 150 min, resulting in a CO2-rich absorbent solution. Four samples, approximately 10 g each, were taken and cooled to 5 °C, 10 °C, 20 °C, and 30 °C respectively in an ice-water bath. 1.0 mL of each sample was then placed in an acidolysis gas measuring device to test the CO2 content of the absorbent solution. The test results are shown in Table 7. The average CO2 load measured at different temperatures varied significantly, with the maximum difference exceeding 9.0 × 10⁻⁶. -2 The results of volumetric sampling (mol CO2 / mol amine) are significantly affected by temperature.

[0120] Table 7. CO2 Load Determination in TETA Absorption Experiment Using Volumetric Sampling Method

[0121]

[0122] Comparative Example 4: Determination of CO2 Load in TETA Desorption Experiment by Volumetric Sampling

[0123] The desorption flask equipped with a reflux condenser was placed in an oil bath heater and heated to 130°C. The TETA-rich absorbent obtained in Comparative Example 3 was then added to the desorption flask. Samples were taken every 30 minutes, and the CO2 load was measured using the acid-hydrolysis gas chromatography method. Desorption was considered complete when the CO2 load of the absorbent showed no significant change, resulting in a lean desorption solution. Six samples, approximately 10g each, were taken and cooled in an ice-water bath to 90°C, 70°C, 50°C, 30°C, 20°C, and 10°C, respectively. 1.0mL of each sample was then placed in the acid-hydrolysis gas chromatography device to measure the CO2 content of the absorbent. The test results are shown in Table 8. The average CO2 load measured at different temperatures varied considerably, with the maximum difference exceeding 9.8 × 10⁻⁶. -2 The results of volumetric sampling (mol CO2 / mol amine) are significantly affected by temperature.

[0124] Table 8. CO2 load determination in TETA desorption experiments using volumetric sampling method

[0125]

[0126] The measurement results of Example 1 and Comparative Example 1 are shown in Table 9.

[0127] Table 9 Comparison of gravimetric and volumetric sampling test results in MEA absorption experiments.

[0128]

[0129] As shown in Table 9, the standard deviation of the gravimetric sampling measurement is 1.05 × 10⁻⁶. -4 The standard deviation of the volumetric sampling measurement is 2.83 × 10⁻⁶. -2 Gravimetric sampling for CO2 load measurement is not affected by sample temperature, while volumetric sampling for CO2 load measurement is significantly affected by sample temperature. Therefore, gravimetric sampling yields more accurate results.

[0130] The measurement results of Example 2 and Comparative Example 2 are shown in Table 10.

[0131] Table 10 Comparison of gravimetric and volumetric sampling results in MEA desorption experiments

[0132]

[0133] As shown in Table 10, the standard deviation of the gravimetric sampling measurement is 2.39 × 10⁻⁶. -4 The standard deviation of the volumetric sampling measurement is 2.16 × 10⁻⁶.-2 Gravimetric sampling for CO2 load measurement is not affected by sample temperature, while volumetric sampling for CO2 load measurement is significantly affected by sample temperature. Therefore, gravimetric sampling yields more accurate results.

[0134] The measurement results of Example 3 and Comparative Example 3 are shown in Table 11.

[0135] Table 11 Comparison of gravimetric and volumetric sampling test results in TETA absorption experiments

[0136]

[0137] As shown in Table 11, the standard deviation of the gravimetric sampling measurement is 9.56 × 10⁻⁶. -4 The standard deviation of the volumetric sampling measurement is 4.06 × 10⁻⁶. -2 Gravimetric sampling for CO2 load measurement is not affected by sample temperature, while volumetric sampling for CO2 load measurement is significantly affected by sample temperature. Therefore, gravimetric sampling yields more accurate results.

[0138] The measurement results of Example 4 and Comparative Example 4 are shown in Table 12.

[0139] Table 12 Comparison of gravimetric and volumetric sampling results in TETA desorption experiments

[0140]

[0141] As shown in Table 12, the standard deviation of the gravimetric sampling measurement is 2.72 × 10⁻⁶. -4 The standard deviation of the volumetric sampling measurement is 3.62 × 10⁻⁶. -2 Gravimetric sampling for CO2 load measurement is not affected by sample temperature, while volumetric sampling for CO2 load measurement is significantly affected by sample temperature. Therefore, gravimetric sampling yields more accurate results.

[0142] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for determining the CO2 load in an organic amine absorbent, characterized in that, Includes the following steps: (1) Add the sealing liquid to the water level bottle of the acidolysis gas measuring device, rotate the three-way valve to the three-way position, raise the position of the water level bottle, so that the liquid level of the sealing liquid in the gas measuring column reaches the top mark. (2) Place the acid standard solution into the acid burette of the acidolysis gas measuring device and record the initial liquid level. (2) Weigh out the organic amine absorbent sample containing carbon dioxide gas by mass, place it in an Erlenmeyer flask, add deionized water and methyl orange indicator; then place the Erlenmeyer flask in the acidolysis gas measuring device and seal it, adjust the height of the water level bottle to be level with the liquid surface of the gas measuring tube, and record the scale V1 of the gas measuring tube. (3) Add the acid standard solution to the titration endpoint and record the graduations on the acid burette. (4) Continue to add excess acid to fully release CO2 from the sample until the liquid level in the gas measuring tube stops changing, and record the graduations on the acid burette. (5) Move the water level bottle up and down until the liquid level in the water level bottle is the same as the liquid level in the gas measuring tube. At this time, the gas pressure above the solution is the same as the external gas pressure. Record the scale V2 of the gas measuring tube. (6) Calculate the total amount of CO2 released in the organic amine solution sample by acid decomposition. Total mass Then calculate the mass m of the organic amine solution in the sample. solution The amount of substance n of organic amines amine Finally, the CO2 load of the organic amine solution by mass and the CO2 load of the organic amine by mole were calculated.

2. The method according to claim 1, characterized in that, The sealing solution is a saturated NaCl solution, acidified with 1% hydrochloric acid until the 0.1% methyl orange indicator turns red.

3. The method according to claim 1, characterized in that, Calculate the total amount of CO2 released from the organic amine solution sample by acid decomposition. Total mass Calculate according to the formulas shown in Equation I and Equation II respectively: in, This represents the amount of CO2 released from the organic amine solution sample, expressed in mol. V2 represents the mass of CO2 released by the acid hydrolysis of the organic amine solution sample, in g; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level is equal to that in the water level bottle, in mL. t is the total volume of the acid standard solution added, in mL; t is the room temperature at the time of measurement, in °C.

4. The method according to claim 1, characterized in that, The mass of the organic amine solution in the sample is calculated according to the formula shown in Equation III: Where, m solution The mass of the organic amine solution in the sample is the mass of the organic amine sample after removing the mass of the loaded CO2, in g; m0 is the mass of the organic amine sample weighed, in g. V2 is the total volume of the acid standard solution added, in mL; t is the room temperature at the time of measurement, in °C; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is equal, in mL.

5. The method according to claim 1, characterized in that, The amount of organic amine in the organic amine solution of the sample is calculated according to the formula shown in Equation IV: Where, n amine The amount of organic amine in the sample taken is expressed in mol; C acid The concentration of the acid standard solution is expressed in mol / L.

6. The method according to claim 1, characterized in that, The CO2 load of the organic amine solution, by mass, is calculated as shown in Equation V: Where, α m CO2 loading of organic amine solution by mass, expressed in g CO2 / g solution; m0 represents the mass of CO2 released by the acid decomposition of the organic amine solution sample, in g; m0 represents the mass of the organic amine sample weighed, in g. V2 is the total volume of the acid standard solution added, in mL; t is the room temperature at the time of measurement, in °C; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is equal, in mL.

7. The method according to claim 1, characterized in that, The calculation of the CO2 load of the organic amine solution, in molar terms, is shown in Equation VI: Where, α n CO2 loading of an organic amine solution by mole, expressed in mol CO2 / mol amine; V2 is the total volume of the acid standard solution added, in mL; (V2-V1) is the difference in the reading of the gas measuring tube before and after acid hydrolysis when the liquid level in the water level bottle is the same, in mL; t is the room temperature at the time of measurement, in °C.

8. The method according to claim 1, characterized in that, The organic amines include, but are not limited to, one or more of the following: ethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), diethylene glycolamine (DGA), diethanolamine (DEA), triethanolamine (TEA), N-methyldiethanolamine (MDEA), piperazine (PZ), ethylenediamine (EDA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA).

9. The method according to claim 1, characterized in that, The acid in the acid standard solution is selected from hydrochloric acid and / or sulfuric acid.

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