Anhydrous binary solid-liquid phase change carbon dioxide absorbent and solid phase regeneration method thereof

Abstract

This invention relates to the field of carbon dioxide chemical absorption and phase change separation technology, and particularly to an anhydrous binary solid-liquid phase change carbon dioxide absorbent and its solid-phase regeneration method. The absorbent consists only of reactive amine A and cooperating amine B, without added water or a third component. Cooperating amine B simultaneously serves as an auxiliary proton acceptor for the deprotonation of zwitterionic intermediates and a low-polarity continuous liquid phase. After absorption, the system spontaneously forms a crystalline-rich solid phase and a lean liquid phase, and solid-liquid separation and solid-phase thermal regeneration are performed based on the bifunctional synergistic coefficient and enrichment window. This technology can achieve a high proportion of enrichment in the solid phase under high absorption loads while maintaining good cycle stability. This invention achieves spontaneous solid-liquid separation after carbon dioxide absorption without the need for an additional third solvent or independent phase-separating agent, resulting in a simpler system composition and reducing the complexity of component design and operational control.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide chemical absorption and phase change separation technology, and to an anhydrous binary solid-liquid phase change carbon dioxide absorbent and its solid-phase regeneration method, and more particularly to a phase change absorption system that achieves efficient carbon dioxide absorption, solid-liquid phase separation and selective solid-phase regeneration through dual-function synergy. Background Technology

[0002] carbon dioxide( Chemical absorption remains one of the most engineering-feasible mainstream methods in post-combustion carbon capture due to its fast absorption rate, large gas throughput, and mature technology. However, traditional water-soluble organic amine absorbents, especially those with a mass fraction... Systems represented by aqueous solutions of alcoholic amines require heating a large amount of water during regeneration, resulting in a heavy burden of sensible heat and latent heat of vaporization. Traditional MEA absorbent in Under regeneration conditions, the total regeneration energy consumption is typically approximately The latent heat of vaporization and sensible heat of solution account for a relatively high proportion of the absorption, which is one of the main bottlenecks for the large-scale application of chemical absorption methods. The basic idea of ​​phase change absorbents is to maintain a homogeneous phase before absorption, and then undergo liquid-liquid or liquid-solid phase separation after absorption, thus... The absorbed products are enriched in the rich phase, and only the rich phase is regenerated, thereby reducing the regeneration volume and reducing the consumption of sensible and latent heat.

[0003] With the development of non-aqueous absorbents and phase change absorbents, research has gradually shifted from whether phase separation is achievable to how to balance absorption capacity, phase separation behavior, regeneration energy consumption, viscosity, and cycle stability. Recent reviews further point out that while phase change absorbents have significant potential in reducing regeneration energy consumption and cycle costs, the field still faces challenges such as a lack of unified design guidelines for formulation construction, insufficient understanding of the absorption-phase separation-regeneration coupling mechanism, and an unsystematic performance evaluation system. For non-aqueous systems, while reducing water content is beneficial for reducing regeneration energy consumption, excessively low water content may lead to new problems such as decreased absorption capacity, reduced regeneration efficiency, or deterioration of phase separation behavior. Therefore, how to simultaneously achieve high load, controllable phase separation, and low-volume regeneration under low-water or anhydrous conditions remains a key technical challenge in this field.

[0004] Based on existing patents, one of the solutions that is closest to this application in terms of composition is Chinese invention publication number CN114011207B, entitled "A Low-Energy Polyamine Liquid-Liquid Phase Change Absorbent for Carbon Capture." This invention discloses... A liquid-liquid phase change system containing water, using dimethylethanolamine (DMEA) as the main absorbent, n-butanol (n-BuOH) as the phase separation agent, and anhydrous piperazine (PZ) as the absorption promoter; its technical focus lies in the absorption of DMEA / -BuOH / PZ / After absorption saturation, the system forms an upper-layer depleted layer. Xianghe Lower-class rich Appearance, and make rich appearance Distribution reached The above desorption energy consumption is approximately This scheme demonstrates the application potential of the DMEA and PZ combination in phase change absorption, but it is essentially still a liquid-liquid phase change route with aqueous ternary components or higher, requiring the additional introduction of n-BuOH as a phase-separating agent. The disclosed focus is on reducing the volume ratio of the rich phase and the heat load of liquid-liquid regeneration, but it does not address the problem of simultaneously achieving reaction promotion and induced crystallization solid-liquid phase separation in an anhydrous binary system using only one synergistic component. In other words, the phase separation and absorption promotion functions in this invention are achieved synergistically by different components, and the technical route differs substantially from that of anhydrous binary solid-liquid phase change systems. Another type of prior art similar to this application is the non-aqueous ternary solid-liquid phase change system. For example, Chinese invention publication CN115253601B, entitled "A Solid-Liquid Phase Change Two-Phase Amine Absorbent for Carbon Dioxide Capture and Its Application," discloses a combination of triethylenetetramine (TETA), 2-amino-2-methyl-1-propanol (AMP), and... A non-aqueous ternary system composed of methylformamide (NMF); requiring protection of NMF as a percentage of the total integral. The volume ratio of TETA to AMP is It also emphasizes that after reaching a certain absorption load, a powdery solid precipitate will form. It is enriched in the solid phase and is rich in... The volume of the solid phase can occupy the total volume During regeneration, only the solid phase is affected. heating Its embodiments also show that when the TETA / AMP ratio is... NMF percentage When the system is close to saturation, solid-liquid phase separation occurs, with the solid phase accounting for approximately [percentage missing]. It has concentrated of Load. This approach has shifted its technological focus to powdered solid products and solid-phase regeneration only, but its core remains the division of different functions among the components in the ternary system: TETA is mainly responsible for increasing the absorption load, AMP mainly acts as an inducer to control the phase change, and NMF acts as an organic solvent to maintain the system's fluidity and stability. Although this type of approach improves the solid-liquid phase separation and regeneration volume issues, based on the published information, it still does not provide a unified construction criterion applicable to anhydrous binary systems, nor does it establish a quantitative control logic that couples reaction enhancement, solid-phase enrichment, and regeneration initiation. For example, publication number CN116688726B, entitled "A Solid-Liquid Phase Change Carbon Dioxide Absorbent with Controllable Phase Change Time Node and Its Application," discloses a mixture of hydroxyethyl ethylenediamine (AEEA), AMP, and... A non-aqueous ternary system composed of methylpyrrolidone (NMP) was used to adjust the AEEA concentration. To delay the formation of solid precipitates, allowing the solid-liquid phase transition to occur near absorption saturation; this requires the protection of the rich... The solid phase mass as a percentage of the total absorbent mass ,in Content as a percentage of total absorption The patent employs microwave regeneration of the solid phase. From an engineering perspective, this addresses the issue of premature solidification under low load potentially causing equipment blockage, representing an improvement in the control of the solid-liquid phase transition time. However, based on its disclosed content, the technical focus of this solution remains on delaying the precipitation time through the third component AEEA, classifying it as a time-controlled ternary system. Its innovation does not lie in establishing a quantitative criterion determined by the system's inherent synergistic effects, directly applicable to defining the absorbent composition and triggering regeneration. Therefore, it remains difficult to answer the structure-activity relationship question of which synergistic component in an anhydrous binary system can both increase the reactive amine loading and simultaneously induce the formation of a crystalline solid phase.

[0005] Furthermore, regarding the regeneration process, Chinese invention publication CN113318572B, entitled "A Method for Controlling the Regeneration of Organic Alcohols as a Carbon Dioxide Phase Change Absorbent and Its Application," discloses a method of separating the rich phase after absorption reaches equilibrium, and then adding [the following to the rich phase]... Organic alcohols, and , This invention describes a method for desorption under specific conditions. It is applicable to various phase change systems, including TETA / DMCA, MAPA / DEEA, and several aqueous systems. The key technical focus is on improving the regeneration efficiency and cycle count of the rich phase by adding an external organic alcohol. This approach demonstrates that existing technologies have addressed the difficulty of rich phase regeneration, but their solutions involve introducing additional regulators during the regeneration stage, increasing the complexity of the process and component management. Furthermore, this invention focuses on enhancing post-regeneration treatment rather than the configuration design of the absorbent system itself or selective regeneration directly triggered by the system's phase window. Notably, regarding the screening of phase change absorbents, publication number CN116230115B, entitled "A Screening Method for Phase Change Absorbents Based on Machine Learning and Quantum Chemical Calculations," uses viscosity, two-phase stability, rich phase volume ratio, absorption capacity, absorption rate, and regeneration energy consumption as performance indicators for modeling and analysis. This invention provides a methodological tool for high-throughput screening of phase change absorbents, but it is essentially a screening method and does not form a structure-process integrated technical solution that can directly constrain the composition, phase separation behavior, and regeneration start-up conditions of a specific anhydrous binary absorbent, nor does it propose increasing the loading of reactive amines and... Quantitative construction parameters for characterization of solid-phase enrichment coupling.

[0006] In summary, while existing technologies have disclosed aqueous liquid-liquid phase change systems, non-aqueous ternary solid-liquid phase change systems, phase change time node control systems, and systems with added regeneration regulators, they generally suffer from the following shortcomings: First, the system construction is highly dependent on ternary or multi-component formulations, with different functions often undertaken by different components. There is a lack of anhydrous binary systems without a third component, where the second component can simultaneously perform both reaction synergy and phase change induction functions. Second, most existing technologies optimize formulations through empirical ratios or single performance indicators, lacking the ability to improve absorption load, Third, existing regeneration schemes mostly use fixed temperature, fixed time or external additives for desorption, and lack an operating logic that triggers selective solid phase regeneration based on the enrichment window of the system after absorption.

[0007] Therefore, it is necessary to develop a method that can achieve high efficiency in anhydrous binary systems. There remains a clear and realistic technological demand for novel carbon dioxide absorbents and methods that combine absorption and solid-liquid phase change with selective solid-phase regeneration based on system synergy and enrichment states. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides an anhydrous binary solid-liquid phase change carbon dioxide absorbent and its solid-phase regeneration method, aiming to solve the following technical problems existing in current carbon dioxide phase change absorption technologies: Existing phase change absorbents mostly rely on aqueous systems or ternary or higher composite systems. Different functions are usually performed by different components, making it difficult to achieve both efficient carbon dioxide absorption and stable solid-liquid phase change separation in an anhydrous binary system.

[0009] Existing technologies for absorbent construction mostly rely on empirical ratios and single performance optimizations, lacking quantitative criteria that can uniformly characterize the increase of reactive amine loading, the enrichment of carbon dioxide into the solid phase, and the control of solid phase volume fraction. This results in a lack of clear basis for absorbent design and operation control.

[0010] Existing regeneration methods mostly employ desorption at fixed temperatures and times or with added additives. There is a lack of a selective solid-phase regeneration method based on the enrichment state window of the system after absorption, making it difficult to balance regeneration efficiency, energy consumption control, and cycle stability.

[0011] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides an anhydrous binary solid-liquid phase change carbon dioxide absorbent, wherein the absorbent is composed of a reactive amine. With synergistic amines The system is composed of no added water and, except for the reacting amine... With synergistic amines No third component is introduced. "Anhydrous" means that no water is actively added during the preparation process, and the total water content of the system is preferably less than [a certain value]. More preferably lower than The reacting amine To have two compatible The amino site of the reaction, and the cyclic diamine capable of forming carbamate via a zwitterionic mechanism; the cooperating amine It is a tertiary amine alcohol that is liquid at the carbon dioxide absorption temperature.

[0012] Furthermore, the synergistic amine In the aforementioned anhydrous binary system, it does not merely exist as an inert solvent, but simultaneously fulfills two functions: firstly, as a reactive amine. - The first is an auxiliary proton acceptor for the deprotonation of zwitterionic intermediates; the second is a low-polarity continuous liquid phase relative to the ionic absorption products, used to induce the precipitation of the absorption products and spontaneously form a carbon dioxide-enriched crystalline solid phase and a carbon dioxide-depleted liquid phase.

[0013] Preferably, the reactive amine Piperazine, the synergistic amine for -Dimethylethanolamine; reactant amine based on total mass of absorbent. mass fraction is Preferred More preferably The remainder is a co-amine. .

[0014] Preferably, the absorbent is prepared by reacting an amine... Adding synergistic amines Mix the ingredients under stirring to form a homogeneous liquid phase; if necessary, the temperature can be appropriately increased to promote dissolution, but the preparation temperature is preferably not higher than [temperature missing]. .

[0015] In this invention, the absorbent absorbs... The initial phase is preferably a single liquid phase. During absorption, as ionic products are gradually generated, the absorbent spontaneously separates into solid and liquid phases after reaching the predetermined absorption state, forming a carbon dioxide-enriched crystalline solid phase and a carbon dioxide-depleted liquid phase. The carbon dioxide-containing gas can be pure. It can also be included The preferred absorption method for the mixed gas is bubbling contact absorption, and the preferred absorption temperature is... .

[0016] To characterize synergistic amines This invention establishes a bifunctional synergistic coefficient in anhydrous binary absorbents, demonstrating the bifunctional synergistic effect. Its expression is: in, To react amine The estimated balance carbon dioxide load is preferably calculated using the following formula: In the formula, This represents the total amount of carbon dioxide absorbed by the system when it reaches equilibrium. Reactive amine in the absorbent The initial amount of substance. The total amount of substance of carbon dioxide. The determination can be performed by any one or a combination of the following methods: weighing method, acid hydrolysis volumetric method, total carbon analysis method, and inlet / outlet gas concentration integration method. For reactive amines The upper limit of the baseline carbon dioxide load when relying on self-deprotonation without the addition of an external proton acceptor.

[0017] Preferred, baseline carbon dioxide load limit It can be determined based on theoretical stoichiometry, or it can be determined without the addition of co-amines. The control experiment showed that when the amine reacted... When piperazine is used, the upper limit of the baseline carbon dioxide load is... Preferred selection .

[0018] The distribution ratio of absorbed carbon dioxide in the solid phase is preferably calculated using the following formula: In the formula, This represents the amount of carbon dioxide in the solid phase after separation. This represents the amount of carbon dioxide in the separated liquid phase.

[0019] The volume fraction of the carbon dioxide-enriched solid phase after absorption is preferably calculated using the following formula: In the formula, This represents the volume of the solid phase after separation. This represents the volume of the liquid phase after separation. and It can be obtained through methods such as static layer reading, reading after centrifugation, image recognition, or online liquid level detection.

[0020] Furthermore, this invention uses a dual-function synergy coefficient As the synergistic amine The criterion for possessing dual-functional synergistic effects, namely the synergistic amine. Not only does it make the reacting amine The actual load exceeds its reference load limit, and the absorbed carbon dioxide is preferentially enriched in the solid phase with a controlled volume fraction. For the preferred piperazine / -Dimethylethanolamine system, when piperazine mass fraction is When, satisfy , , ; Preferably, the absorbent can achieve , , At this time, the dual-function synergy coefficient Not less than .

[0021] Furthermore, the present invention also provides a solid-phase regeneration method for anhydrous binary solid-liquid phase change carbon dioxide absorbent. This method does not simply involve conventional heating of the precipitated solid phase after absorption; instead, it first determines whether the system has entered an enrichment window suitable for selective solid-phase regeneration based on its phase distribution state.

[0022] Preferably, the present invention constructs the following trigger function: in, This is the regeneration trigger criterion; when When, solid-liquid separation and solid-phase regeneration are performed; when At that time, continue to absorb or adjust the operating status.

[0023] Preferred, , , , For piperazine / -Dimethylethanolamine preferred system, can be , , .

[0024] like Figure 1 As shown, based on the above triggering criteria, the solid-phase regeneration method of the present invention includes: contacting the absorbent with carbon dioxide-containing gas for absorption; when the system meets the enrichment window condition, stopping absorption and performing solid-liquid separation to obtain a carbon dioxide-enriched crystalline solid phase and a lean liquid; subsequently, only the carbon dioxide-enriched crystalline solid phase is heated for desorption to obtain a regenerated liquid; finally, the regenerated liquid is cooled and mixed with the aforementioned lean liquid to restore the regenerated binary absorbent and enter the next absorption cycle. The solid-liquid separation is preferably achieved by static sedimentation, filtration, centrifugation, or a combination thereof.

[0025] Preferably, the desorption temperature of the carbon dioxide-enriched crystalline solid phase is [temperature value missing]. More preferably Desorption can be carried out under normal pressure, reduced pressure, or inert gas purging conditions; the endpoint of desorption is determined by the complete transformation of the crystalline solid phase into a clear liquid and the cessation of continuous release of carbon dioxide.

[0026] Furthermore, when the regenerated solution is mixed with the lean solution, the reaction is carried out according to the recovery reaction amine. With synergistic amines The original composition ratio is used for recombining to ensure the absorbent composition remains stable in the next cycle. For the preferred piperazine / The dimethylethanolamine system was continuously processed. After the absorption-separation-solid phase regeneration-recombination cycle, the carbon dioxide loading based on piperazine is still not less than .

[0027] Furthermore, the dual-function synergy coefficient It is not only used for determining the operational status after absorption, but also for the construction and screening of anhydrous binary solid-liquid phase change absorbents. Specifically, for candidate reactive amines... / synergistic amine Combinations were measured separately under the same absorption conditions. , and and combined with reactive amines of calculate When the candidate system satisfies Furthermore, when a separable crystalline solid phase is formed after absorption, the synergistic amine can be identified. To meet the requirements of this invention, a bifunctional synergistic amine is proposed.

[0028] Preferably, in a preferred embodiment of the present invention, piperazine is used as a reactive amine. , -Dimethylethanolamine as a cooperating amine An anhydrous binary solid-liquid phase change carbon dioxide absorption system is formed without introducing a third component.

[0029] By means of the above technical solution, the present invention provides an anhydrous binary solid-liquid phase change carbon dioxide absorbent and its solid-phase regeneration method, which has at least the following beneficial effects: 1. This invention constructs an anhydrous binary solid-liquid phase change carbon dioxide absorption system. It can achieve spontaneous solid-liquid separation after carbon dioxide absorption without the need to introduce a third solvent or independent phase separation agent. The system composition is simpler, which helps to reduce the complexity of component design and operation control.

[0030] 2. In this invention, the synergistic amine has the dual function of assisting proton acceptor and phase transition induction medium. It can not only increase the actual carbon dioxide loading of the reactive amine, but also promote the preferential enrichment of absorption products in the crystalline solid phase, thereby achieving a synergistic unity of improved absorption performance and solid phase separation characteristics.

[0031] 3. This invention proposes a method based on dual-function synergy coefficients. The selective solid-phase regeneration technology route with solid-phase enrichment window can regenerate only the carbon dioxide enriched solid phase after the absorption system reaches the preset enrichment state, reducing the regeneration treatment volume, which is conducive to improving the targeting of the regeneration process, and taking into account the stability of the system for recycling. Attached Figure Description

[0032] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart of the solid-phase regeneration method in this invention; Figure 2 This is a schematic diagram of the carbon dioxide absorption device in Embodiment 1 of the present invention; Figure 3 This is an external image of the solid-liquid phase transition after absorption in Example 1 of the present invention; Figure 4 This is a schematic diagram of the carbon dioxide desorption device in Embodiment 1 of the present invention; Figure 5This is a graph showing the absorption rate at different PZ mass fractions in Example 2 of the present invention; Figure 6 This is a graph showing the total absorption capacity at different PZ mass fractions in Example 2 of the present invention; Figure 7 This is a PZ-based absorption loading diagram for different PZ mass fractions in Example 2 of the present invention; Figure 8 The solid-liquid volume ratio diagrams for different PZ mass fractions in Example 2 of the present invention are shown below. Distribution map; Figure 9 This is a diagram showing the phase transition time and phase transition load under different PZ mass fractions in Embodiment 2 of the present invention; Figure 10 This is a graph showing the carbon dioxide absorption rate at different absorption temperatures in Example 3 of the present invention; Figure 11 This is a diagram showing the equilibrium carbon dioxide absorption load at different absorption temperatures in Example 3 of the present invention; Figure 12 This is a graph showing the desorption efficiency at different desorption temperatures in Example 4 of the present invention; Figure 13 This is a graph showing the change in absorption load after 5 absorption-regeneration cycles in Example 4 of the present invention; Figure 14 The fresh absorbent, the liquid phase after absorption, and the solid phase after absorption in Example 5 of this invention. 13 C NMR spectrum; Figure 15 This is the energy barrier diagram of the deprotonation and further absorption pathway in Embodiment 5 of the present invention. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This will allow for a full understanding of how the present application uses technical means to solve technical problems and achieve technical effects, and to facilitate its implementation.

[0034] Example 1: Anhydrous binary piperazine / Preparation of dimethylethanolamine absorbent and its carbon dioxide absorption experiment.

[0035] In this embodiment, piperazine (PZ) was selected as the reactive amine. Dimethylethanolamine (DMEA) was used as a cooperating amine to construct an anhydrous binary solid-liquid phase change carbon dioxide absorption system. The piperazine used had a purity of [missing information]. Used - Dimethylethanolamine purity not less than The purity of the carbon dioxide gas used is Based on the total mass of the absorbent Calculate and weigh piperazine. weigh -Dimethylethanolamine The mass fraction of piperazine is Add piperazine In dimethylethanolamine, the mixture is stirred and mixed at room temperature until a homogeneous and clear liquid is formed, thus obtaining an anhydrous binary absorbent.

[0036] Will Adding absorbent The three-necked flask is placed in a pre-temperature controlled water bath. A carbon dioxide cylinder is used as the gas source, and the carbon dioxide injection rate is controlled by a gas mass flow controller. And a soap film flow meter is used to monitor the outlet gas flow rate, such as Figure 2 As shown. During the absorption process, the real-time carbon dioxide absorption rate of the anhydrous binary absorbent system is determined based on the difference in carbon dioxide flow rates between the inlet and outlet, and the total carbon dioxide absorption load is obtained by integrating the absorption rate over time. As carbon dioxide absorption proceeds, the system gradually changes from an initially homogeneous and transparent liquid to a turbid state, and further precipitates a white solid product. When the outlet gas flow rate equals the inlet gas flow rate, the system is considered to have reached absorption equilibrium, and gas flow is stopped. After absorption is stopped, the resulting mixture is allowed to stand and separate, yielding a carbon dioxide-enriched crystalline solid phase and a lean liquid. The solid phase is in powder or crystalline form and exhibits good separability, such as... Figure 3 As shown. The separated carbon dioxide-rich crystalline solid phase is transferred to a desorption device, where... Under certain conditions, heating desorption is performed; desorption is considered complete when the solid completely disappears and transforms into a clear liquid, and the system no longer continuously releases carbon dioxide. The regenerated solution is then cooled to room temperature and remixed with the aforementioned lean solution to obtain the regenerated absorbent. The above absorption-phase separation-solid phase regeneration process can be repeated, such as... Figure 4 As shown.

[0037] Testing of the absorption system obtained in this embodiment shows that, under the above composition and operating conditions, the equilibrium carbon dioxide absorption load, calculated as piperazine, is: The proportion of carbon dioxide absorbed in the solid phase exceeds [a certain percentage]. The volume fraction of the carbon dioxide-rich solid phase after absorption is: The results show that the anhydrous binary absorbent system constructed in this embodiment can simultaneously achieve a high carbon dioxide absorption load, a high proportion of carbon dioxide enrichment into the solid phase, and a moderate solid phase volume fraction without the introduction of external water and a third component.

[0038] According to the dual-function synergy coefficient defined in this invention The expression is: in, To react amine The calculated balance carbon dioxide load, For reactive amines The theoretical upper limit of carbon dioxide load when relying on self-deprotonation without the addition of an external proton acceptor. This represents the distribution ratio of absorbed carbon dioxide in the solid phase. This represents the volume fraction of the carbon dioxide-enriched solid phase after absorption. In this embodiment... When it is piperazine, take ;Will , , Substituting, we get: Right now .

[0039] The above results demonstrate that, in this embodiment... Dimethylethanolamine not only exists as a continuous liquid medium, but also plays a dual role as an auxiliary proton acceptor and a phase transition induction medium in the system, enabling the system to enter the enrichment window required by this invention even under high absorption load, and to achieve subsequent selective solid-phase regeneration.

[0040] Example 2: Determination of the composition window and enrichment window of anhydrous binary absorbent with different piperazine mass fractions.

[0041] To determine the preferred composition range of the anhydrous binary solid-liquid phase change carbon dioxide absorbent of the present invention, this embodiment compares and investigates absorbents with different piperazine mass fractions under the same experimental apparatus and operating conditions as in Example 1. The reactive amine used is piperazine (PZ), and the co-reacting amine is... -Dimethylethanolamine (DMEA), the total mass of the absorbent is 1 Five formulations were set up, with PZ mass fraction as follows: , , , and Accordingly, the amounts of PZ and DMEA added in each group were as follows: , , , and .

[0042] Each absorbent group was prepared into an initial homogeneous liquid phase using the same method as in Example 1, and absorbed by passing pure carbon dioxide under isothermal conditions. The carbon dioxide inlet flow rate was maintained at [value missing]. When the outlet flow rate equals the inlet flow rate, the system is considered to have reached absorption equilibrium, and ventilation is terminated. For each system group, the absorption rate, total absorption capacity, and equilibrium carbon dioxide absorption load (in PZ) are recorded. Solid-liquid phase separation behavior, carbon dioxide-rich solid phase volume fraction Distribution ratio of carbon dioxide in the solid phase Phase transition time and phase change load Among them, phase transition time The time from the introduction of carbon dioxide to the first stable and identifiable solid phase precipitation in the system; phase change loading. The carbon dioxide absorption load, expressed in PZ, at the aforementioned phase transition time.

[0043] The real-time absorption rate and total absorption capacity results of each group of absorbents show that as the mass fraction of PZ increases, the absorption rate and total absorption capacity of the system continuously increase, such as... Figure 5 and Figure 6 As shown. This indicates that increasing the concentration of the reacting amine helps to accelerate the reaction. The absorption process increases the total absorption capacity. However, the carbon dioxide absorption loading, calculated as PZ, gradually decreases with increasing PZ mass fraction, from... group Descending to group ,like Figure 7 As shown in the figure, this result indicates that when the PZ content is too high, the utilization efficiency per unit PZ molecule actually decreases.

[0044] After static separation of the absorbed system, it was observed that all five formulations produced white powdery or crystalline solid products with good separability. This indicates that in the anhydrous binary system described in this invention, the combination of PZ and DMEA can induce a solid-liquid phase transition after absorption, rather than forming a viscous slurry that is difficult to separate. Further examination of the solid volume fraction revealed that as the mass fraction of PZ decreased from... Increase to After absorption, the volume fraction of the solid phase decreased from... Rising sharply to ,like Figure 8 As shown in the figure. Simultaneously, the phase transition node is significantly advanced, meaning the system begins to precipitate solids at lower absorption loads and shorter absorption times. This result indicates that while excessively high PZ content helps increase the overall absorption rate of the system, it leads to premature solidification and an excessively high solid-phase ratio, which is detrimental to subsequent separation and regeneration operations, such as... Figure 9 As shown.

[0045] Further analysis of the distribution of carbon dioxide in the solid and liquid phases reveals that, across the entire range of ratios investigated, the distribution ratio of absorbed carbon dioxide in the solid phase remains consistently high. The above demonstrates that the solid phase formed in the anhydrous binary system of this invention is always a carbon dioxide-enriched phase, while the liquid phase is a carbon dioxide-depleted phase. This result indicates that while changing the PZ mass fraction significantly affects the amount of solid precipitation and the phase transition node, it does not significantly weaken the solid phase's ability to enrich carbon dioxide.

[0046] In this invention, a dual-function synergy coefficient is employed. The formula for quantitative evaluation of different component systems is as follows: in, To react amine The calculated balance carbon dioxide load, This represents the theoretical upper limit of carbon dioxide loading for reactive amines when they undergo self-deprotonation without an external proton acceptor. This represents the distribution ratio of absorbed carbon dioxide in the solid phase. This represents the volume fraction of the carbon dioxide-rich solid phase after absorption. When the amine reacts... When it is PZ, take .

[0047] For preferred The test results for group PZ are as follows: , , Substituting this into the above formula, we get: Right now This indicates that the system can simultaneously satisfy the two conditions of "absorption load higher than the theoretical upper limit" and "high proportion of carbon dioxide enriched into the solid phase with a moderate volume fraction".

[0048] From a comprehensive application perspective, although low PZ mass fraction arrays have a higher absorption load per unit PZ, their total absorption capacity and absorption rate are relatively low due to the lower total concentration of reacting amines. Conversely, high PZ mass fraction arrays, while possessing higher total absorption capacity and faster absorption rate, exhibit premature solidification and a high solid volume fraction, significantly increasing the operational burden of subsequent solid-liquid separation and solid-phase regeneration. In comparison, PZ mass fractions of... The system achieves a better balance between absorption loading, solid volume fraction, and carbon dioxide enrichment: its absorption loading in terms of PZ reaches The solid volume fraction is The distribution ratio of carbon dioxide in the solid phase is higher than that of carbon dioxide in the solid phase. This falls within the preferred enrichment window defined in this invention. Therefore, the preferred composition range of the anhydrous binary absorbent of this invention can be determined as the PZ mass fraction. More preferably .

[0049] This embodiment demonstrates that by adjusting the composition ratio of PZ to DMEA, the absorption capacity, phase transition node, and enrichment state of carbon dioxide in the solid phase after absorption can be effectively controlled. The mass fraction of PZ is [value missing]. The anhydrous binary absorbent system exhibits the best overall performance in terms of high absorption load, moderate solid phase ratio and high enrichment solid phase formation, and can be used as a preferred component embodiment of the present invention.

[0050] Example 3: Experiment on the absorption performance and temperature adaptability of the preferred anhydrous binary absorbent at different absorption temperatures.

[0051] This embodiment uses the anhydrous binary absorbent system determined in Examples 1 and 2, namely, piperazine (PZ) with a mass fraction of [missing information]. PZ / - Dimethylethanolamine (DMEA) system. Based on the total mass of the absorbent. Calculation, PZ weighing DMEA weighing Stir and mix at room temperature until a homogeneous, clear liquid is formed.

[0052] To investigate the effect of absorption temperature on the performance of the anhydrous binary solid-liquid phase change carbon dioxide absorption system of this invention, the absorption temperature was set to [temperature value missing] while keeping other operating conditions constant. , , and A comparative experiment was conducted. Each group of experiments was conducted within... The experiment was conducted in a three-necked flask, with the amount of absorbent added being... The carbon dioxide inlet flow rate is controlled at [value]. The inlet and outlet gas flow rate difference was recorded using the same method as in Example 1, and the real-time carbon dioxide absorption rate and equilibrium carbon dioxide absorption load (in PZ) of the system were calculated. When the outlet flow rate equaled the inlet flow rate, the system was considered to have reached absorption equilibrium, and the gas supply was terminated. Each experiment was repeated twice, and the results showed good repeatability. Experimental results indicate that... Within the specified temperature range, as the absorption temperature increases, both the real-time carbon dioxide absorption rate and the final equilibrium carbon dioxide absorption load of the system show a gradual decreasing trend. Figure 10 As shown in the figure, this result indicates that higher temperatures are not conducive to maintaining high carbon dioxide solubility in this system, nor are they conducive to the exothermic absorption reaction between amine and carbon dioxide, thus leading to a certain degree of decrease in absorption performance.

[0053] Meanwhile, as the absorption temperature increases, the time required for the system to reach absorption equilibrium actually shortens, indicating that the system approaches equilibrium more quickly at higher temperatures. Nevertheless, throughout the entire temperature range under investigation, the preferred anhydrous binary system described in this embodiment maintained a high absorption load, with its equilibrium carbon dioxide absorption load (calculated as PZ) consistently exceeding... ,like Figure 11 As shown, this indicates that the absorbent of the present invention still has good absorption capacity and strong temperature adaptability within the common temperature range of flue gas after industrial combustion.

[0054] Based on the preferred composition determined in Example 2, the mass fraction of PZ is: The PZ / DMEA system is not only in a superior compositional window, but also... The system can maintain a high absorption load within the absorption temperature range. This indicates that the anhydrous binary solid-liquid phase change carbon dioxide absorption system of the present invention has good adaptability to temperature fluctuations and can operate stably under different inlet flue gas temperatures, providing a good prerequisite for subsequent solid-phase regeneration based on enrichment window triggering.

[0055] Therefore, this embodiment demonstrates that, without changing the composition of the absorbent, by controlling the absorption temperature at... Within the specified range, the preferred anhydrous binary absorbent systems of this invention can maintain a high carbon dioxide absorption load and exhibit temperature adaptability suitable for industrial post-combustion flue gas conditions.

[0056] Example 4: Evaluation of solid-phase regeneration triggered by the enrichment window of anhydrous binary absorbent, cycle stability and regeneration heat consumption.

[0057] This embodiment uses the anhydrous binary absorbent composition determined in Examples 1 and 2, namely piperazine (PZ) with a mass fraction of [missing information]. PZ / - Dimethylethanolamine (DMEA) system. Based on the total mass of the absorbent. Calculation, PZ weighing DMEA weighing The mixture was stirred and mixed at room temperature until a homogeneous, clear liquid was formed. Carbon dioxide absorption was then performed using the same method as in Example 1. After the system reached absorption equilibrium, it was allowed to stand and separate to obtain a carbon dioxide-rich solid phase and a lean liquid. At absorption equilibrium, the carbon dioxide absorption loading of this anhydrous binary absorbent system, calculated as PZ, was... After absorption, the distribution ratio of carbon dioxide in the solid phase is higher than that of carbon dioxide. The volume fraction of carbon dioxide-rich solid phase is Substituting the above parameters into the dual-function synergy coefficient defined in this invention... Calculation formula: in, To react amine The calculated balance carbon dioxide load, For reactive amines The theoretical upper limit of carbon dioxide load when relying on self-deprotonation without the addition of an external proton acceptor. This represents the distribution ratio of absorbed carbon dioxide in the solid phase. This represents the volume fraction of the carbon dioxide-enriched solid phase after absorption. In this embodiment... When it is PZ, take Then we can obtain: Right now .

[0058] Therefore, this embodiment will , and In The interval serves as the enrichment window criterion for selective solid-phase regeneration; when the system meets the above conditions, absorption stops and solid-liquid separation is performed, with thermal regeneration only occurring on the carbon dioxide-rich solid phase. For the system used in this embodiment... The PZ / DMEA system's regeneration trigger state corresponds to , , .

[0059] The separated carbon dioxide-rich solid phase was transferred to a desorption device, and comparative experiments were conducted at different desorption temperatures. The desorption temperatures investigated were as follows: , , and During desorption, desorption is considered complete when the solid completely disappears and transforms into a clear liquid, and the system no longer continuously releases carbon dioxide. After desorption, the regenerated solution is cooled to room temperature and remixed with the previously separated lean solution to obtain the regenerated absorbent. Each group of experiments was repeated twice, and the results showed good reproducibility.

[0060] To quantitatively evaluate the regeneration effect at different desorption temperatures, this embodiment uses desorption efficiency. As an evaluation indicator, its expression is: in, For the first The absorption load achieved by the absorbent after regeneration when it absorbs carbon dioxide again. This represents the initial carbon dioxide absorption load of the fresh absorbent. Test results show that the regeneration efficiency of the system significantly increases with increasing desorption temperature, such as... Figure 12 As shown. When the desorption temperature is and At that time, the system remained a turbid white suspension after desorption, indicating that the solid product was not completely decomposed, and the corresponding desorption efficiencies were only [missing information]. and When the desorption temperature rises to At this time, the solid phase can completely decompose and form a homogeneous and transparent liquid, with a desorption efficiency reaching [percentage missing]. It continued to rise to At that time, the desorption efficiency was only higher than It will increase slightly, but will result in additional heat loss, therefore... The preferred solid-phase regeneration temperature for this invention has been determined.

[0061] At the above-mentioned preferred regeneration temperature The preferred absorbent was further subjected to five consecutive absorption-phase separation-solid phase regeneration-recombination cycle experiments, as follows: Figure 13 As shown. The results indicate that the carbon dioxide absorption load of the system after the first cycle is... It remained unchanged even after the 5th cycle. This indicates that the anhydrous binary solid-liquid phase change absorption system of the present invention maintains high absorption capacity and good cycle stability after multiple thermal regenerations, and can meet the requirements for repeated use.

[0062] Furthermore, to evaluate the heat consumption level of the selective solid-phase regeneration route of the present invention, this embodiment measures the sensible heat of the temperature rise during the regeneration process. , latent heat of volatilization Total regeneration heat consumption An estimate is performed. The total regenerative heat consumption is calculated using the following formula: In the formula, The heat of desorption reaction, To increase sensible heat, Latent heat of vaporization. Sensible heat of vaporization. It can be calculated using the following formula: In the formula, To determine the specific heat capacity of the desorbed solid phase, The quality of the solid phase to be regenerated. For the temperature difference during the desorption process, This represents the mass of carbon dioxide released during the regeneration process.

[0063] latent heat of volatilization Latent heat can be calculated using the following formula: In the formula, This refers to the volatile mass of each component during the regeneration process. This refers to the enthalpy of vaporization of the corresponding volatile component. For the preferred system in this embodiment... When estimating heat consumption under certain conditions, the key parameters used include: solid-phase heat capacity. quality of the solid phase to be regenerated The mass of carbon dioxide released during the regeneration process Total volatile mass of volatile components The corresponding enthalpy of vaporization is Based on this, the sensible heat and latent heat are estimated, and combined with the conventional approximation of the desorption reaction heat of amine absorption systems, the preferred anhydrous binary system of this invention can be obtained. The total regenerative heat consumption is .

[0064] Further analysis reveals that the low heat consumption of the preferred system in this embodiment mainly stems from two aspects: firstly, after absorption, only the carbon dioxide-rich solid phase undergoes thermal regeneration, significantly reducing the processing volume entering the regeneration unit; secondly, both PZ and DMEA have high boiling points and low volatility, resulting in minimal latent heat loss. Therefore, this invention achieves a balance between high regeneration efficiency, good cycle stability, and low regeneration heat consumption through the technical route of "enrichment window triggering—solid phase regeneration only".

[0065] In summary, this embodiment demonstrates that: for a PZ mass fraction of... The preferred anhydrous binary absorption system, when the system enters , , In After the enrichment window is reached, high desorption efficiency and good cycling performance can be obtained simply by thermal regeneration of the carbon dioxide-rich solid phase; among which, To optimize the desorption temperature, the system can achieve the following under these conditions: The desorption efficiency remained high even after 5 cycles. With a relatively high absorption load, the total regeneration heat consumption is .

[0066] Example 5: Characterization of the solid phase product structure of the preferred anhydrous binary absorbent and verification of its bifunctional synergistic mechanism.

[0067] This embodiment uses the preferred anhydrous binary absorbent composition determined in Examples 1 and 2, namely, piperazine (PZ) with a mass fraction of [missing information]. PZ / - Dimethylethanolamine (DMEA) system. Based on the total mass of the absorbent. Calculation, PZ weighing DMEA weighing The mixture was stirred and mixed at room temperature until a homogeneous and clear liquid was formed. Carbon dioxide absorption was then performed as described in Example 1. After the system reached absorption equilibrium, it was allowed to stand for separation, and the liquid and solid phase samples were collected separately. To reduce the interference of residual solvent on the characterization results, the separated solid phase sample was first freeze-dried. Then, nuclear magnetic resonance, infrared spectroscopy, X-ray diffraction, thermogravimetric-differential scanning calorimetry, and theoretical calculation analysis were carried out. Among them, the theoretical calculation adopted density functional theory to optimize the geometric configuration of reactants, products and representative molecular pairs, and combined with electrostatic potential, non-covalent interaction and reduced density gradient analysis to verify the absorption and phase transition mechanism of the system of the present invention.

[0068] First, the fresh, unabsorbed sample, the carbon dioxide-depleted liquid phase after absorption, and the carbon dioxide-enriched solid phase after absorption were analyzed. 13 C NMR analysis, such as Figure 14 As shown. The results indicate that the characteristic carbon signal of DMEA can be observed in the fresh absorbent, while PZ, due to its highly symmetrical structure, exhibits... The characteristic peak at this location is a single characteristic peak; after absorption and solid-liquid separation, only the characteristic signal of DMEA is retained in the liquid phase sample, and no signal related to carbon dioxide binding products is observed, indicating that the liquid phase is a carbon dioxide-depleted phase; while in the solid phase sample, the characteristic peak at this location is observed. and The two sets of significant new peaks correspond to carbamate species formed by the reaction of PZ with carbon dioxide, indicating that the carbon dioxide absorption products are mainly enriched in the solid phase. Simultaneously, near-peaks can also be observed in the solid phase. The weak peak; combined with the carbon dioxide-saturated water-soluble PZ control sample. 13 NMR results indicate that the weak peak can be attributed to the hydrolysis of a small amount of carbamate by deuterated water during sample preparation, resulting in the in-situ formation of trace amounts of carbonate / bicarbonate, rather than the large amount of carbonate byproducts actually present in the anhydrous system of this invention. Therefore, the preferred system of this invention, after absorbing carbon dioxide, forms a carbon dioxide-rich solid phase dominated by PZ carbamate, while the liquid phase is mainly a DMEA-enriched lean solution.

[0069] Furthermore, FT-IR analysis was performed on the fresh absorbent, the liquid phase after absorption, and the solid phase after absorption. The results showed that the infrared spectra of the fresh absorbent and the separated liquid phase were highly similar, indicating that the liquid phase composition was close to that of the original absorbent, further confirming that the liquid phase was mainly a DMEA-enriched phase. In contrast, a series of new characteristic absorption peaks appeared in the spectrum of the solid phase sample: located at... and The new peak at this location can be attributed to ammonium salt-related vibrations. The peak at that location can be attributed to Vibration, located Multiple weak peaks within the interval correspond to The asymmetric and symmetric stretching vibrations of the groups indicate that an urethane structure has been formed in the solid phase; furthermore, in The interval shows weak The stretching vibrations indicate that the solid phase contains a small amount of DMEA. The above results are consistent with... 13 The NMR results were consistent, further confirming that the carbon dioxide-rich solid phase was mainly composed of PZ carbamate and its related protonated species. XRD and TG-DSC analyses of the solid phase sample revealed that its XRD pattern... , , , , , and The presence of sharp diffraction peaks indicates that the solid phase has good crystallinity and is an easily separable crystalline powder rather than a viscous gel. TG-DSC results show that the solid phase... Weightlessness begins to occur, A distinct endothermic peak appears at this point, corresponding to the maximum decomposition rate of PZ-based carbamate; to Around 10:00 AM, the thermal decomposition process was basically completed. The above results demonstrate that the carbon dioxide enrichment product of the system of this invention not only possesses a good separable crystalline morphology, but also can achieve effective decomposition at a relatively mild temperature, providing a structural basis for subsequent low-energy solid-phase regeneration.

[0070] Regarding mechanism verification, theoretical calculations show that PZ first forms a zwitterionic intermediate with carbon dioxide, and then can generate stable carbamates via both the DMEA-involved deprotonation pathway and the PZ-involved deprotonation pathway, as shown below. Figure 15 As shown. For the deprotonation pathway involving DMEA, its activation energy is... The Gibbs free energy changes to For the deprotonation pathway involving PZ itself, its activation energy is: The Gibbs free energy changes to This indicates that DMEA has a slight advantage in deprotonation both kinetically and thermodynamically. Meanwhile, the subsequent second-molecule carbon dioxide absorption pathway also has a low barrier, with the activation energy of a representative step being... The Gibbs free energy changes to This indicates that it is theoretically feasible for PZ to further form some dicarboxylate species. Combined with the measured carbon dioxide absorption loading of the preferred system of this invention, it reaches... It exceeds the theoretical upper limit of PZ under the classical zwitterionic mechanism. The results demonstrate that DMEA is not simply a solvent in the system of this invention, but rather participates in the absorption reaction as an auxiliary proton acceptor, reducing the consumption of free PZ as a proton acceptor and enabling more PZ to participate in carbon dioxide absorption.

[0071] Furthermore, analysis of dipole moments and non-covalent interactions of the components and representative molecular pairs before and after absorption revealed that DMEA and PZ before absorption were both relatively neutral components with low polarity; after absorption, PZ was converted to carbamate, resulting in a significant increase in molecular polarity, while the ion pair formed by the carbamate and protonated amine exhibited higher overall polarity. This polarity difference between the product ion pair and the residual DMEA disrupted the original homogeneous state, thereby driving phase separation. Further IMH and RDG results showed that... and , There are obvious strong electrostatic interactions and hydrogen bonding interactions between them, among which and The hydrogen bond distances are respectively and All are significantly shorter than In molecular pairs This result indicates that the absorbed products tend to form strong associated ion pairs with protonated amines and aggregate and precipitate, rather than continue to dissolve stably in the DMEA continuous phase, thereby inducing the formation of a carbon dioxide-rich crystalline solid phase.

[0072] In summary, this embodiment verifies the dual-functional synergistic mechanism of the preferred anhydrous binary system of the present invention from both experimental characterization and theoretical calculation perspectives: on the one hand, DMEA improves the actual carbon dioxide absorption load of PZ by participating in zwitterion deprotonation; on the other hand, the highly polar carbamate / protonated amine ion pair formed after absorption undergoes selective aggregation and precipitation due to the significant polarity difference between it and the low-polarity DMEA continuous phase, ultimately forming an easily separable crystalline solid phase. This demonstrates that DMEA in the present invention simultaneously plays a dual role as an auxiliary proton acceptor and a phase transition induction medium.

[0073] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Since the above embodiments are substantially similar to the method embodiments, their descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0074] The above embodiments provide a detailed description of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An anhydrous binary solid-liquid phase change carbon dioxide absorbent, characterized in that, The absorbent is composed of reactive amines. and synergistic amines Composition, free of added water and except for the reactant amine. and synergistic amines A third component besides; The reactive amine The cooperating amine is a cyclic diamine having two amino sites that can react with carbon dioxide and capable of forming carbamates via a zwitterionic mechanism. It is a tertiary amine alcohol that is liquid at the carbon dioxide absorption temperature; The synergistic amine Simultaneously, as a reactive amine - The auxiliary proton acceptor deprotonated by zwitterionic intermediates, and the low-polarity continuous liquid phase in which the induced absorption products precipitate and spontaneously form a carbon dioxide-enriched crystalline solid phase and a carbon dioxide-depleted liquid phase.

2. The anhydrous binary solid-liquid phase change carbon dioxide absorbent according to claim 1, characterized in that, The absorbent satisfies a bifunctional synergistic coefficient when absorbing carbon dioxide to equilibrium. Dual-function synergy coefficient The calculation formula is: In the formula, To react amine The calculated balance carbon dioxide load; For reactive amines The upper limit of the baseline carbon dioxide load when relying on self-deprotonation without the addition of an external proton acceptor; This represents the distribution ratio of the absorbed carbon dioxide in the solid phase. This represents the volume fraction of the carbon dioxide-enriched crystalline solid phase after absorption.

3. The anhydrous binary solid-liquid phase change carbon dioxide absorbent according to claim 1, characterized in that, The reactive amine Piperazine, the synergistic amine for -Dimethylethanolamine.

4. The anhydrous binary solid-liquid phase change carbon dioxide absorbent according to claim 3, characterized in that, Based on the total mass of the absorbent, the mass fraction of piperazine is: .

5. The anhydrous binary solid-liquid phase change carbon dioxide absorbent according to claim 3, characterized in that, The mass fraction of piperazine is: Furthermore, when the absorbent absorbs carbon dioxide to equilibrium, the equilibrium carbon dioxide loading, calculated as piperazine, is not less than [amount not specified]. The distribution ratio of absorbed carbon dioxide in the solid phase Not less than The volume fraction of carbon dioxide enriched in the solid phase after absorption for .

6. A solid-phase regeneration method for an anhydrous binary solid-liquid phase change carbon dioxide absorbent, comprising preparing the anhydrous binary solid-liquid phase change carbon dioxide absorbent as described in any one of claims 1-5 to form an absorbent with an initial homogeneous liquid phase, characterized in that... Includes the following steps: S1. The absorbent is contacted with carbon dioxide-containing gas for absorption, forming a carbon dioxide-enriched crystalline solid phase and a lean liquid; S2, Calculations used to construct the trigger function Dual-function synergy coefficient And determine whether it has entered the enrichment window where selective solid-phase regeneration can be performed based on the phase distribution state of the absorbent; If so, then stop absorption and perform solid-liquid separation to obtain carbon dioxide-enriched crystalline solid phase and lean liquid, and proceed to step S3; If not, return to step S1 to continue absorption; S3. Only the carbon dioxide enriched crystalline solid phase obtained in step S2 is heated and desorbed to obtain a regenerated liquid; S4. Mix the regenerated liquid with the lean liquid obtained in step S2 to obtain the regenerated absorbent and return it to the next absorption cycle.

7. The solid-phase regeneration method according to claim 6, characterized in that, The trigger function The expression is: in, For the corresponding dual-function synergy coefficient The preset threshold; For the corresponding allocation ratio The preset threshold; , Volume fraction The minimum and maximum values.

8. The solid-phase regeneration method according to claim 6, characterized in that, The enrichment window satisfies the dual-function synergy coefficient. The distribution ratio of absorbed carbon dioxide in the solid phase Not less than And the volume fraction of carbon dioxide enriched in the solid phase after absorption for ; When the reaction amine Piperazine and the synergistic amine for When -dimethylethanolamine is used, the enrichment window is: Dual-function synergy coefficient The distribution ratio of absorbed carbon dioxide in the solid phase Not less than The volume fraction of carbon dioxide enriched in the solid phase after absorption for .

9. The solid-phase regeneration method according to claim 6, characterized in that, The absorption temperature of step S1 is The heating and desorption temperature in step S3 is The desorption process ends when the crystalline solid phase has completely transformed into a clear liquid and no more carbon dioxide is released.

10. The solid-phase regeneration method according to claim 6, characterized in that, When the absorbent is of mass fraction piperazine / In the 1,2-dimethylethanolamine system, continuous operation is carried out. After one absorption-regeneration cycle, the carbon dioxide loading, calculated as piperazine, is not less than .

Images