Detection method for evaluating interface oxidative degradation process of carbon capture chemical absorbent

Abstract

The invention discloses a detection method for evaluating an interface oxidative degradation process of a carbon capture chemical absorbent, belongs to the technical field of absorbent degradation of a carbon capture chemical absorption system, and particularly relates to evaluation of the interface oxidative degradation process. In order to solve the problems that an existing carbon capture chemical absorbent oxidative degradation process evaluation system cannot effectively simulate actual working conditions, cannot reflect an interface oxidative degradation process, is long in experimental period, is discontinuous in detection process and the like, the invention provides a novel detection method. Through the steps of aerosol micro-interface generation, multi-channel oxidative degradation reaction, optical signal real-time dynamic capture and the like, the oxidative degradation reaction process of a chemical absorbent on a micro scale is detected, on one hand, the interface reaction process which cannot be simulated in a volume phase experiment system can be explored; on the other hand, the problems of long experimental period, low detection time resolution and the like in the traditional oxidative degradation reaction process evaluation can be avoided, and a more efficient detection effect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of carbon capture chemical absorption system absorbent degradation technology, and relates to the evaluation of the oxidative degradation process at the interface, specifically to a detection method for evaluating the oxidative degradation process at the interface of carbon capture chemical absorbents. Background Technology

[0002] In chemical absorption CO2 capture systems, organic amine molecules undergo a reversible reaction with CO2 to generate carbamate and protonated amines. However, due to the complex composition of flue gas, O2, SO2, and NO2 all affect the degradation behavior of the absorbent. Among these, O2 is often present in higher concentrations than the other two impurity gases, thus having a dominant influence. Reactions involving oxygen are collectively referred to as oxidative degradation, which mainly occurs in the absorption tower and generally accounts for 70% of the total amine loss.

[0003] In chemical absorption CO2 capture systems, pollutant emissions typically originate from the absorption tower. Common types include physical entrainment, gaseous emissions, and aerosol emissions, with aerosol emissions being the most complex and difficult to control. Besides removing effective components such as organic amines, aerosol emissions also carry away oxidative degradation products, causing environmental impacts. Therefore, evaluating the oxidative degradation process of the absorbent, and its behavior at heterogeneous interfaces, is of significant importance.

[0004] However, current evaluations of the oxidative degradation process of carbon capture chemical absorbents are mostly based on bulk systems, which involves long experimental cycles and requires periodic sample removal for testing, resulting in low temporal resolution. Furthermore, this evaluation method is not representative and cannot reflect the absorbent degradation behavior occurring at interfaces under actual operating conditions. Summary of the Invention

[0005] The purpose of this invention is to address the problems of existing evaluation systems for the oxidative degradation process of carbon capture chemical absorbents, such as their inability to effectively simulate actual working conditions, their inability to reflect the interfacial oxidative degradation process, and their long experimental cycles and discontinuous detection processes. Therefore, this invention proposes a detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention proposes a novel detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents, based on laser-captured aerosol micro-interface technology, comprising the following steps: (1) Aerosol micro-interface generation: The chemical absorbent to be evaluated in solution form is prepared into micro-droplet state by ultrasonic atomizer to simulate an interfacial phase different from the bulk phase, and then introduced into the corresponding multi-channel reactor by carrier gas for subsequent reaction.

[0007] (2) Multi-channel oxidative degradation reaction: By uniformly distributing the aerosol micro-interface in the multi-channel reactor, oxidative reactions under different conditions are carried out, simulating the oxidative degradation process of the same absorbent droplets under different oxygen concentrations and different reaction times in one go.

[0008] (3) Real-time dynamic capture of optical signals: Laser capture of a single droplet is used. After the aerosol micro-interface is stably captured, the inelastic Raman signal of the droplet is excited and collected by an online spectrometer and a high-speed camera to obtain continuous in-situ changes in the state of the droplet.

[0009] In some preferred embodiments, the wavelength of the laser is 532 nm and the laser power is 60~200 mW.

[0010] The beneficial effects of this invention are as follows: This invention introduces laser-captured aerosol micro-interface technology to detect the oxidative degradation process of chemical absorbents at a microscale through steps such as aerosol micro-interface generation, multi-channel oxidative degradation reaction, and real-time dynamic capture of optical signals. On the one hand, it can explore interfacial reaction processes that cannot be simulated in bulk experimental systems; on the other hand, it can avoid the problems of long experimental cycles and low detection time resolution in traditional oxidative degradation reaction process evaluation, achieving a more efficient detection effect. Attached Figure Description

[0011] Figure 1 This is a schematic flowchart of the detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents according to the present invention; Figure 2 These are the droplet capture interfaces under different laser powers; Figure 3 These are spectral signal diagrams of different functional groups. Detailed Implementation

[0012] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0013] To address the shortcomings of current methods for evaluating the oxidative degradation process of carbon capture chemical absorbents, which fail to reflect actual operating conditions and involve complex experimental procedures, this invention develops a novel detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents. Figure 1 As shown, the method itself is based on laser capture technology. Through steps such as aerosol micro-interface generation, multi-channel oxidative degradation reaction, and real-time dynamic capture of optical signals, the state of the absorbent in the aerosol micro-interface morphology is captured, thereby evaluating the oxidative degradation process of carbon capture chemical absorbents at the interface.

[0014] Example 1 (1) Aerosol micro-interface generation: 30% (w / w) N-methyldiethanolamine (MDEA) solution is converted into microdroplet form (droplet diameter is 5~20 micrometers) by ultrasonic atomizer and introduced into multi-channel reactor by nitrogen gas.

[0015] (2) Multi-channel oxidative degradation reaction: High-purity oxygen with volume fractions of 0%, 5%, 10%, 30%, 50% and 80% is continuously introduced into multiple chambers inside the multi-channel reactor. MDEA microdroplets in the chambers react with oxygen to degrade and generate degradation products such as 1,4-dimethylpiperazine, 2-oxazolone, 3-methyl-5-ethylpyridine and N-methylimidazolium.

[0016] (3) Real-time dynamic capture of optical signals: The droplets are irradiated with a 532 nm laser. Compared with the initial chain structure of MDEA, the oxidative degradation products generated in step (2) are mostly cyclic structures with different bond structures and functional groups. When the microdroplets containing these products are stably captured by the 532 nm laser, the inelastic Raman signal of the droplets will be excited and captured in real time by an online spectrometer and a high-speed camera. Figure 3 By fitting the peak position of the spike with Mie scattering, high time-resolved information on droplet size and refractive index can be obtained, which can be used to deduce the oxidative degradation reaction process of the absorbent at the interface.

[0017] like Figure 2 The images show interface images of droplets captured using different laser powers (34mW~90mW). It can be seen that the diffraction spot of the droplet is smaller when the laser power is higher. This is because, as the laser power decreases, the upward scattering force decreases and becomes less than the downward gradient force. The net force then moves downwards, causing the equilibrium position of the captured droplet to gradually decrease, and the droplet to gradually approach the glass slide, resulting in a larger diffraction spot observed in the planar image. Therefore, when using this method to study the oxidative degradation process at the absorbent interface, it is necessary to select an appropriate laser power, such as 60~200 mW.

[0018] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects: In practical use, the aerosol micro-interface generation step in this method transforms the bulk carbon capture chemical absorbent into an aerosol micro-interface state, simulating interface-scale conditions and more closely resembling the working conditions within the absorption tower of a carbon capture system in actual engineering; the multi-channel oxidative degradation reaction step in this method, through a high-throughput experimental approach, completes the oxidative degradation reaction process of the absorbent under different conditions in one go, resulting in more efficient evaluation; the real-time dynamic capture step of the optical signal in this method, through an online spectrometer and a high-speed camera, captures the changes in droplet state in real time, inverts the transformation of its physical and chemical properties, and tracks the oxidative degradation process of the carbon capture chemical absorbent at the interface online. This method detects the oxidative degradation reaction process of the chemical absorbent at a microscale, which on the one hand can explore interface reaction processes that cannot be simulated in bulk experimental systems, and on the other hand can avoid the problems of long experimental cycles and low detection time resolution in traditional oxidative degradation reaction process evaluation, achieving a more efficient detection effect.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "conversion," "introduction," "capture," etc., should be interpreted broadly. For example, "introduction" can mean injection or inflow; it can mean introduction through a metal pipeline or a Teflon pipeline; it can mean direct introduction or indirect introduction through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents, characterized in that, The method includes the following steps: converting the chemical absorbent to be evaluated into an aerosol micro-interface state, placing it in multiple gas environments with different oxygen concentrations for oxidative degradation reaction, using laser to capture individual droplets, and acquiring in-situ changes in the droplet state in real time.

2. The detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents according to claim 1, characterized in that, The process of converting the chemical absorbent to be evaluated into an aerosol micro-interface state includes: converting the chemical absorbent to be evaluated into microdroplet form using an ultrasonic atomizer and suspending it in a gaseous medium.

3. The detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents according to claim 2, characterized in that, The microdroplet morphology is controlled so that the droplet diameter is 5-20 micrometers.

4. The detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents according to claim 1, characterized in that, A multi-channel reactor was used to enable the simultaneous oxidative degradation reaction of the same absorbent aerosol micro-interface at different concentrations and durations.

5. The detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents according to claim 1, characterized in that, The laser has a wavelength of 532 nm and a power of 60~200 mW.

6. The detection method for evaluating the interfacial oxidative degradation process of carbon capture chemical absorbents according to claim 1, characterized in that, After a single droplet is captured by a laser, the in-situ changes in the droplet's state are acquired in real time using an online spectrometer and a high-speed camera.

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