Evaluation method and determination device for degradation performance of carbon capture absorbent

Abstract

The invention relates to a carbon capture absorbent degradation performance evaluation method and a determination device, the method comprises the following steps: accelerating aging degradation of a to-be-detected sample under high pressure oxygen and heating conditions, simulating the oxidation process of an absorbent in long-term operation, and shortening the experimental period; in the test process, the pressure and temperature of the reaction kettle are automatically collected, a pressure-time curve is established, and the degradation resistance of the sample is comprehensively judged according to the pressure drop rate and inflection point time. The method for evaluating the degradation performance of the carbon capture absorbent can be used for rapidly and comprehensively evaluating the sample, and meanwhile, the degradation degree can be analyzed and judged without the help of high-end equipment such as cation chromatography and gas chromatography, so that the method is convenient and efficient; the method is particularly suitable for testing and optimizing the oxidation resistance of novel absorbents such as composite absorbents and phase change absorbents.

Description

Technical Field

[0001] The present invention relates to the field of carbon capture technology, and in particular to a rapid and comprehensive method for evaluating the degradation performance of carbon capture absorbents, which is particularly suitable for testing and optimizing the antioxidant performance of new absorbents such as composite absorbents and phase change absorbents. Background Art

[0002] Chemical absorption is currently the most mature and promising carbon capture technology. Carbon capture technologies (such as post-combustion capture) often use amine absorbents (such as MEA, DEA, MDEA) to absorb CO. However, in the presence of high temperature, oxygen and metal ions, the absorbent is prone to oxidative degradation, leading to the following problems: 1) Decreased efficiency: degradation products (such as organic acids and nitrosamines) reduce the CO absorption capacity; 2) Equipment corrosion: degradation products accelerate pipeline corrosion; 3) Environmental risks: by-products such as nitrosamines are toxic. The purpose of studying the antioxidant mechanism and performance of absorbents is to inhibit oxidation reactions, extend the life of absorbents and reduce operating costs. Existing evaluation methods focus more on basic performance such as absorption rate and regeneration energy consumption, but lack systematic testing of oxidative degradation.

[0003] Zhejiang University's doctoral thesis "Research on the Performance of Diamine Low-Water Absorbents for Flue Gas CO2 Capture" mentioned an oxidative degradation experiment with a test temperature of 65°C, a mixed gas pressure stable at 0.5MPa, and a test period of up to 4 weeks.

[0004] CN116328498A discloses a carbon dioxide absorbent, its application, and a method for treating carbon dioxide in flue gas. The invention discloses a strong oxidative degradation reaction device in which electric heating is used to maintain the absorbent temperature at 65°C and a 0.6MP pure oxygen atmosphere is introduced for 28 days. After the experiment, cation chromatography is used to analyze the content of various substances in the absorbent before and after the experiment, and the total degradation rate is calculated.

[0005] CN1381301A, in its first example, describes an evaluation method in which an MEA solution is subjected to intensive degradation in an autoclave at 110°C and an oxygen partial pressure of 0.6 MPa. The degradation rate of the MEA solution is then measured after the reaction time has elapsed. However, this method only evaluates the MEA degradation rate at a specific time point.

[0006] The above test method has some shortcomings, which are mainly reflected in two aspects: first, the test cycle is too long, up to 4 weeks; second, the evaluation is not comprehensive enough and cannot simulate the degradation of samples in long-term operating environments and throughout their life cycle. Summary of the Invention

[0007] The present disclosure provides a rapid and comprehensive method for evaluating the degradation performance of carbon capture absorbents. This method subjects the sample to accelerated aging and degradation under high-pressure oxygen conditions at 90-120°C, simulating the oxidation process of the absorbent during long-term operation and shortening the experimental cycle. During the test, the reactor pressure and temperature are automatically collected, and a pressure-time curve is established. The sample's resistance to degradation is comprehensively determined based on the pressure drop rate and inflection point time. This method can be used to screen formulations and predict absorbent service life. This method for evaluating the degradation performance of carbon capture absorbents enables rapid and comprehensive sample evaluation and is particularly suitable for testing and optimizing the antioxidant properties of novel absorbents, such as composite absorbents and phase-change absorbents.

[0008] The method for evaluating the degradation performance of a carbon capture absorbent provided by the present disclosure mainly comprises the following steps:

[0009] S1, sample loading: the carbon capture absorbent sample and the magnet are placed in a high-pressure reactor with a polytetrafluoroethylene liner and sealed;

[0010] S2, inflation: fill the autoclave with oxygen to the set pressure, which is 0.2-0.3 MPa higher than the test pressure, and slowly release the pressure using the bleed valve; repeat the purging step more than twice; adjust the bleed valve and slowly release the air to the test pressure at room temperature;

[0011] S3, oxidation: Place the autoclave in a magnetic stirring temperature control device, set the test temperature, start stirring and heating;

[0012] S4, data collection: After the test starts, the pressure and temperature of the reactor are automatically collected to maintain the set test temperature;

[0013] S5, data analysis: Establish a pressure-time curve and comprehensively determine the sample's anti-degradation ability based on the curve's decline rate and inflection point time. The slower the curve declines, that is, the slower the slope and the longer the inflection point time, the stronger the sample's anti-degradation ability.

[0014] Furthermore, in step S1, the carbon capture absorbent sample is a new sample or a sample loaded with carbon dioxide, and the carbon dioxide loading amount is any value from zero to saturation.

[0015] Furthermore, in step S1, a catalyst is added to the carbon capture absorbent sample to accelerate oxidation, and the catalyst includes: Fe 3+ or Cu 2+ ion.

[0016] Furthermore, in step S2, the temperature of the gas during inflation is room temperature or 25°C; and the gas inflation pressure is not less than 1.5 MPa.

[0017] Furthermore, in step S2, the ratio δ of the amount of gas to the amount of organic amine is not less than 20%; that is:

[0018]

[0019] Where n 气 is the amount of gas in mol; n 液 is the sum of the amounts of organic amines in the sample;

[0020] The amount of gas is calculated using the ideal gas state equation, namely:

[0021]

[0022] Where P is the gas pressure at room temperature, in Pa; V is the gas volume, which is the volume of the reactor minus the volume occupied by the sample, in m 3 ; T is room temperature, unit K; R is the gas constant, value is 8.314, unit is J / (mol·K);

[0023] The amount of organic amine is calculated according to the following formula:

[0024]

[0025] Where n 液 is the sum of the amounts of organic amines in the sample; m is the mass of the sample, in g; c is the mass concentration of the organic amine; M is the relative molecular mass of the organic amine, in g / mol; α is the number of nitrogen atoms contained in the molecular structure of the organic amine.

[0026] Furthermore, in step S3, the test temperature is set to 90-120°C.

[0027] Furthermore, in steps S3 and S4, heating and heat preservation are performed by using any one of an electric heating jacket, a constant temperature box, an oven or an oil bath.

[0028] Furthermore, the method further includes the following steps: stopping the test after an inflection point appears on the pressure-time curve, and the test time is no more than 72 hours.

[0029] Compared with the existing technology, the beneficial effects of the present disclosure are: ① by accelerating the aging and degradation of the sample under high-pressure oxygen and temperature conditions of 90-120°C, the required test can be completed in a shorter time; ② it can simulate the degradation of the sample under a long-term operating environment and throughout its entire life cycle; ③ based on the pressure drop rate and inflection point time, the sample's anti-degradation ability can be comprehensively determined without the need for high-end equipment such as cation chromatography and gas chromatography to analyze and determine the degree of degradation; ④ the test process is simple to operate and data is collected automatically. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0031] Figure 1 is a schematic structural diagram of an exemplary assay device according to the present disclosure;

[0032] Figure 2 Schematic diagram of an exemplary high-pressure reactor structure;

[0033] Figure 3 An assessment flow chart for an exemplary embodiment;

[0034] Figure 4 Comparison of test results of MEA (ethanolamine) and MDEA (N-methyldiethanolamine) at a test temperature of 90°C;

[0035] Figure 5 The test results of MEA (ethanolamine) are compared under the test temperatures of 90℃ and 100℃ respectively. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0037] In view of the current situation that there is no dedicated method for evaluating the degradation performance of carbon capture absorbents, the present disclosure provides a rapid and comprehensive method for evaluating the degradation performance of carbon capture absorbents. The test sample is subjected to accelerated aging degradation in a certain high-pressure oxygen atmosphere and a certain test temperature. During the test, the reactor pressure is automatically collected and a pressure-time curve is established to achieve a rapid and comprehensive degradation performance evaluation of the carbon capture absorbent.

[0038] Assessment Principle: At a certain temperature, the absorbent reacts with oxygen. As oxygen consumption causes the reactor pressure to drop, monitoring this pressure change reflects the extent of the absorbent's degradation. This method is simple and effective, eliminating the need for high-end equipment such as cation chromatography or gas chromatography-mass spectrometry (GC-MS) to determine degradation.

[0039] Based on the above evaluation principles, the method provided by the present disclosure can complete the required tests in a relatively short period of time, and at the same time, comprehensively determine the sample's anti-degradation ability based on the pressure drop rate and inflection point time, thereby providing an important reference for screening formulas and predicting the service life of absorbents.

[0040] In an exemplary embodiment, the carbon capture absorbent degradation performance evaluation method according to the present disclosure is as shown in the attached figure. Figure 3 As shown, it mainly includes the following steps:

[0041] (1) Sample loading: Place a certain amount of test sample and magnet into a high-pressure reactor lined with polytetrafluoroethylene and seal it.

[0042] (2) Inflation: Inflate with oxygen to a specific pressure, which is 0.2-0.3 MPa higher than the test pressure, and slowly release the pressure using the bleed valve; repeat the purge step more than twice; adjust the bleed valve and slowly release the air to the test pressure at room temperature.

[0043] (3) Oxidation: Place the high-pressure reactor into the device, set the test temperature, and start stirring and heating.

[0044] The test temperature is preferably 90-120°C. If the test temperature is too low, the oxidation rate will be too slow, resulting in a prolonged test time; if the test temperature is too high, the oxidation rate will be too fast, resulting in a less distinct inflection point in the curve. Furthermore, the appropriate test temperature can be selected based on the pressure drop trend for absorbent comparison, providing a basis for formula screening and predicting absorbent service life.

[0045] The temperature during gas inflation is preferably room temperature or 25°C. The gas inflation pressure is preferably not less than 1.5 MPa. The higher the pressure, the better it can reduce the effect of water vapor pressure on the oxygen pressure drop during the test, thereby reducing test errors.

[0046] Preferably, the temperature can be controlled by an electric heating jacket, a thermostat, an oven or an oil bath.

[0047] (4) Data collection: After the test starts, the equipment automatically collects pressure and temperature.

[0048] (5) Data Analysis: Establish a pressure-time curve and comprehensively determine the sample's anti-degradation ability based on the curve's rate of decline and inflection point time. The slower the curve declines (the gentler the slope) and the longer the inflection point time, the stronger the sample's anti-degradation ability.

[0049] Preferably, in this embodiment, the ratio (δ) of the amount of gas to the amount of organic amine is not less than 20%. The amount of gas, the sum of the amount of organic amine in the sample, and the ratio of the two are calculated according to formulas ①, ②, and ③ respectively:

[0050]

[0051] Among them, n 气 is the amount of gas in mol; n 液 is the sum of the amounts of organic amines in the sample;

[0052] The ideal gas state equation is used to calculate the amount of gas:

[0053]

[0054] P is the gas pressure at room temperature, in Pa; V is the gas volume, which is the volume of the reactor minus the volume occupied by the sample, in m 3 ; T is room temperature, unit is K; R is the gas constant, value is 8.314, unit is J / (mol·K);

[0055]

[0056] n 液 is the sum of the amounts of organic amines in the sample, where m is the mass of the sample in g; c is the mass concentration of the organic amine; M is the relative molecular mass of the organic amine in g / mol; and α is the number of nitrogen atoms contained in the molecular structure of the organic amine.

[0057] Preferably, the test is stopped after the pressure-time curve has an inflection point, and the test time is preferably not more than 72 hours.

[0058] According to requirements, the carbon capture absorbent sample is a new sample or a sample loaded with carbon dioxide (the carbon dioxide loading amount is any value from zero to saturation).

[0059] The carbon capture absorbent sample can be optionally added with a catalyst to accelerate oxidation, such as Fe 3+ 、Cu 2+ Ions, etc.

[0060] The automatic recorder can automatically record the temperature and pressure during the test. The data collection period can be 1-1800 seconds, preferably 60 seconds. During the test, pressure is also affected by temperature. Therefore, the automatic recorder is used to collect temperature at the same time to determine whether the pressure drop is affected by temperature.

[0061] An exemplary carbon capture absorbent degradation performance measuring device applied to the above method is shown in the attached Figure 1 and 2 As shown, it mainly includes: a magnetic stirring temperature control device 1, a high-pressure reactor 2, and an automatic recorder 3;

[0062] The high-pressure reactor 2 further includes: 21, a high-pressure reactor body; 22, an air inlet valve; 23, an overpressure automatic pressure relief valve; 24, a pressure transmitter; 25, a temperature sensor; 26, an air outlet valve; and 27, a magnet.

[0063] As a preference, the magnetic stirring temperature control device adopts PID artificial intelligence temperature control with self-tuning function; equipped with forward and reverse rotation function, stirring speed 0-1500r / min.

[0064] The high-pressure reactor is equipped with an air inlet valve 22, an air outlet valve 26, a pressure transmitter 24, a temperature sensor 25 and an overpressure automatic pressure relief valve 23, among which:

[0065] The orifice of the air inlet valve 22 extends deep into the kettle body 21, and the orifice is located in the lower middle part of the kettle body;

[0066] The temperature sensor 25 is inserted into the reactor 21 to monitor the reaction temperature in real time.

[0067] The pressure transmitter 24 is equipped with 3-10 stainless steel heat sinks to ensure efficient heat dissipation and accuracy.

[0068] The autoclave is equipped with a polytetrafluoroethylene liner and preferably has a capacity of 500 ml.

[0069] The automatic recorder is connected to the pressure transmitter 24 and the temperature sensor 25 and can record the pressure and temperature in real time.

[0070] Preferably, the temperature control accuracy of the magnetic stirring temperature control device is no more than ±1°C.

[0071] As a preference, a high-precision digital pressure transmitter is used with a measuring range of 0-5Mpa and an accuracy level better than 0.5. Specific embodiment:

[0073] Example 1

[0074] S1 Sample loading: 150 g of 30% by mass ethanolamine (MEA) aqueous solution and a magnet were placed in a 500 ml high-pressure reactor with a polytetrafluoroethylene liner and sealed.

[0075] S2 inflation: At room temperature of 20°C, fill with oxygen to 2.2-2.3 MPa, and slowly release the pressure using the relief valve; repeat the purge steps twice; adjust the relief valve and slowly release the air to 2.0 MPa.

[0076] S3 oxidation: Place the high-pressure reactor into the device, set the test temperature to 90°C, and start stirring and heating.

[0077] S4 Data collection: After the test starts, the automatic recorder collects temperature and pressure every 60 seconds.

[0078] S5 Data Analysis: Establish a pressure-time curve and comprehensively determine the sample's anti-degradation ability based on the curve's decreasing rate and inflection point time.

[0079]

[0080] Example 2

[0081] S1 Sample loading: 150 g of 30% N-methyldiethanolamine (MDEA) aqueous solution and a magnet were placed in a 500 ml high-pressure reactor with a polytetrafluoroethylene liner and sealed.

[0082] S2 inflation: At room temperature of 20°C, fill with oxygen to 2.2-2.3 MPa, and slowly release the pressure using the relief valve; repeat the purge steps twice; adjust the relief valve and slowly release the air to 2.0 MPa.

[0083] S3 oxidation: Place the high-pressure reactor into the device, set the test temperature to 90°C, and start stirring and heating.

[0084] S4 Data collection: After the test starts, the automatic recorder collects temperature and pressure every 60 seconds.

[0085] S5 Data Analysis: Establish a pressure-time curve and comprehensively determine the sample's anti-degradation ability based on the curve's decreasing rate and inflection point time.

[0086]

[0087] The test results of Example 1 and Example 2 are compared in the attached figure. Figure 4 As shown in the figure, in the early stage of the experiment, the pressure drop rate (slope) of ethanolamine MEA is significantly smaller than that of N-methyldiethanolamine MDEA, indicating that the early antioxidant performance of MEA carbon capture absorbent is worse than that of MDEA; as the experimental time increases, the antioxidant performance of MEA in the later stage is not as good as that of MDEA.

[0088] Example 3

[0089] The test temperature was set to 100°C, and the rest was the same as in Example 1.

[0090] The test results of Example 1 and Example 3 are compared in the attached figure. Figure 5 As shown in the figure, the pressure curve decreases slowly in the early stages and rapidly in the later stages. The higher the test temperature, the greater the rate of decrease in the later stages, indicating faster MEA oxidation and poorer antioxidant properties. Furthermore, the curve has a distinct inflection point at 100°C.

[0091] The above technical solutions are only exemplary embodiments of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and are not limited to the methods described in the above specific embodiments of the present invention. Therefore, the methods described above are only preferred and do not have a restrictive meaning.

Claims

1. A method for evaluating the degradation performance of a carbon capture absorbent, comprising the following steps: S1, sample loading: the carbon capture absorbent sample and the magnet are placed in a high-pressure reactor with a polytetrafluoroethylene liner and sealed; S2, inflation: fill the autoclave with oxygen to the set pressure, which is 0.2-0.3 MPa higher than the test pressure, and slowly release the pressure using the bleed valve; repeat the purging step more than twice; adjust the bleed valve and slowly release the air to the test pressure at room temperature; S3, oxidation: Place the autoclave in a magnetic stirring temperature control device, set the test temperature, start stirring and heating; S4, data collection: After the test starts, the pressure and temperature of the reactor are automatically collected to maintain the set test temperature; S5, data analysis: Establish a pressure-time curve and comprehensively determine the sample's anti-degradation ability based on the curve's decline rate and inflection point time. The slower the curve declines, that is, the slower the slope and the longer the inflection point time, the stronger the sample's anti-degradation ability.

2. The method according to claim 1, characterized in that In the step S1, the carbon capture absorbent sample is a new sample or a sample loaded with carbon dioxide, and the carbon dioxide loading amount is any value from zero to saturation.

3. The method according to claim 1 or 2, characterized in that In step S1, a catalyst is added to the carbon capture absorbent sample to accelerate oxidation, and the catalyst includes: Fe 3+ or Cu 2+ ion.

4. The method according to claim 1, wherein In step S2, the temperature of the gas during inflation is room temperature or 25° C.; and the gas inflation pressure is not less than 1.5 MPa.

5. The method according to claim 4, characterized in that In step S2, the ratio δ of the amount of gas to the amount of organic amine is not less than 20%; that is: Where n 气 is the amount of gas in mol; n 液 is the sum of the amounts of organic amines in the sample; The amount of gas is calculated using the ideal gas state equation, namely: Where P is the gas pressure at room temperature, in Pa; V is the gas volume, which is the volume of the reactor minus the volume occupied by the sample, in m 3 ; T is room temperature, unit K; R is the gas constant, value is 8.314, unit is J / (mol·K); The amount of organic amine is calculated according to the following formula: Wherein, n is the sum of the amounts of organic amines in the sample; m is the mass of the sample, in g; c is the mass concentration of the organic amine; M is the relative molecular mass of the organic amine, in g / mol; α is the number of nitrogen atoms contained in the molecular structure of the organic amine.

6. The method according to claim 1, characterized in that In step S3, the test temperature is set to 90-120°C.

7. The method according to claim 1 or 2, characterized in that In the steps S3 and S4, heating and heat preservation are performed by using any one of an electric heating jacket, a constant temperature box, an oven or an oil bath.

8. The method according to claim 1, further comprising the steps of: The test is stopped after the inflection point appears on the pressure-time curve. The test time shall not exceed 72 hours.

9. A carbon capture absorbent degradation performance measuring device used in the method according to any one of claims 1 to 8, characterized in that: include: A high-pressure reactor for placing magnetons and carbon capture absorbent samples to be tested; A magnetic stirring temperature control device is used to stir the carbon capture absorbent sample accompanied by magnets in the high-pressure reactor and keep the temperature of the reactor at the set temperature; The gas charging and discharging device is used to charge oxygen into the high-pressure reactor and regulate the pressure inside the reactor; a measuring device for measuring in real time the pressure and temperature in the autoclave during the degradation of the carbon capture absorbent sample; The collecting and recording device is used to automatically collect and record the data measured by the measuring device to form a pressure-time curve, providing a basis for evaluating the degradation performance of the carbon capture absorbent.

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