New Monoethanolamine Absorption Technology Using Ionic Liquid as Phase Separator - New Monoethanolamine Absorption Technology Using Ionic Liquid as Phase Separator for Low Energy Biogas Upgrading Research Using Ionic Liquid as Phase Separator - Ionic Liquid Biphase Solvent for Low Energy Biogas Upgrading Research

1. Research background and technical pain point analysis 1. Research background and technical pain point analysis

With the global fossil energy reserves decreasing year by year and the dual-carbon policy continuing to be implemented, the replacement of traditional fossil energy by renewable energy has become the core trend in the development of the energy industry. Biogas, as a typical biomass renewable energy, has the advantages of wide source of raw materials, clean and low-carbon, safe and stable, and can be consumed nearby. It is mainly prepared by anaerobic fermentation of organic wastes such as animal manure, straw, and kitchen waste. It can be widely used in gas heating, power generation, and vehicle bio-natural gas. It is an important way to solve rural waste pollution and realize solid waste resource utilization. However, primary biogas usually contains 30% to 45% carbon dioxide impurities, which greatly reduces the calorific value of gas, reduces combustion efficiency, corrodes gas pipelines, and cannot be directly integrated into the natural gas pipeline network or used as high-quality biomethane. Therefore, the purification and decarbonization of biogas is an essential core process for realizing its industrialization and large-scale utilization. With the global fossil energy reserves decreasing year by year and the dual-carbon policy continuing to be implemented, renewable energy replacing traditional fossil energy has become the core trend of the development of the energy industry. Biogas, as a typical biomass renewable energy source, has the advantages of wide source of raw materials, clean and low-carbon, safe and stable, and can be consumed nearby. It is mainly prepared by anaerobic fermentation of organic wastes such as livestock and poultry manure, straw, and kitchen waste. It can be widely used in gas heating, power generation, and vehicle bio-natural gas. It is an important way to solve rural waste pollution and realize solid waste resource utilization. However, primary biogas usually contains 30% to 45% carbon dioxide impurities, which greatly reduce the calorific value of gas, reduce combustion efficiency, corrode gas pipelines, and cannot be directly incorporated into the natural gas pipeline network or used as high-quality biomethane. Therefore, the purification and decarbonization of biogas is an essential core process to realize its industrialization and large-scale utilization.

At present, the mainstream biogas CO2 capture and purification technologies include membrane separation, pressure swing adsorption, low-temperature distillation, and chemical washing of organic amines. Among them, the monoethanolamine (MEA) chemical absorption method has become the most mature and popular decarbonization technology in industrial applications due to its advantages of large absorption capacity, fast reaction rate, wide adaptation conditions, low equipment investment, and suitability for large-scale continuous production. However, the traditional MEA process has industry pain points that are difficult to break through: the energy consumption of amine liquid regeneration is extremely high, accounting for more than 60% of the operating cost of the entire biogas purification process. At the same time, there are problems such as large solvent volatilization loss, high temperature easy degradation, serious equipment corrosion, and poor long-term operation stability, which greatly limit the large-scale commercialization of this technology. At present, the mainstream biogas CO2 capture and purification technologies include membrane separation, pressure swing adsorption, low-temperature distillation, and organic amine chemical washing. Among them, the monoethanolamine (MEA) chemical absorption method has become the most mature and most popular decarbonization technology in industrial applications due to its advantages of large absorption capacity, fast reaction rate, wide adaptability to working conditions, low equipment investment, and suitability for large-scale continuous production. However, the traditional MEA process has industry pain points that are difficult to break through: the energy consumption of amine liquid regeneration is extremely high, accounting for more than 60% of the operating cost of the entire biogas purification process. At the same time, there are problems such as large solvent volatilization loss, high temperature easy degradation, serious equipment corrosion, and poor long-term operation stability, which greatly limit the large-scale commercialization of this technology.

Ionic liquids (ILs), as a new generation of green solvents, have the outstanding advantages of extremely low volatility, excellent thermal stability, designable structure, and high CO _ 2 selectivity. They are a cutting-edge research direction to replace traditional organic amine solvents and achieve low energy consumption carbon capture. However, pure ionic liquids generally have extremely high viscosity, large gas-liquid mass transfer resistance, and slow absorption kinetics. The efficiency of CO _ 2 capture alone is low. The industry usually uses mixing a small amount of water to reduce the viscosity of the system and strengthen the mass transfer effect. However, simply adding water cannot fundamentally solve the problems of high regeneration energy consumption and large solvent loss, and the space for technical optimization is limited. Ionic liquids (ILs), as a new generation of green solvents, have the outstanding advantages of extremely low volatility, excellent thermal stability, designable structure, and high CO _ 2 selectivity. They are a cutting-edge research direction to replace traditional organic amine solvents and achieve low-energy carbon capture. However, pure ionic liquids generally have extremely high viscosity, high gas-liquid mass transfer resistance, slow absorption kinetic rate, and low CO _ 2 capture efficiency. The industry usually uses mixing a small amount of water to reduce the viscosity of the system and strengthen the mass transfer effect. However, simply adding water cannot fundamentally solve the problems of high regeneration energy consumption and large solvent loss, and the space for technical optimization is limited.

Phase change absorption technology is a breakthrough technology in the field of low-energy carbon capture in recent years. The core principle is to use a functional solvent system to achieve a controllable transformation of the phase state of the absorption and regeneration process: after absorbing CO 2, the system is automatically stratified into a carbon-rich liquid phase and a carbon-poor liquid phase. Only the rich phase with a smaller volume ratio and highly enriched CO 2 needs to be heated and regenerated, which greatly reduces the amount of heating liquid, thereby significantly reducing the regeneration energy consumption and improving the operation efficiency. Systematic research on ionic liquids as phase separation regulators is relatively scarce in the current industry. Traditional phase change systems have defects such as unstable phase separation, poor adaptability to working conditions, and insufficient thermal stability. However, 1-butyl-3-methylimidazolium tetrafluoroborate (BF) ionic liquids possess excellent thermal stability, good gas-liquid permeability, and selective adsorption properties of CO 2, which can effectively regulate the phase structure of aqueous solutions and optimize intermolecular forces. This provides an excellent foundation for the construction of high-performance, low-energy MEA-ILs-water three-phase composite absorption systems. Phase change absorption technology is a breakthrough technology in the field of low-energy carbon capture in recent years. The core principle is to use a functional solvent system to achieve a controllable transformation of the phase state of the absorption and regeneration process: after absorbing CO 2, the system is automatically stratified into a carbon-rich liquid phase and a carbon-poor liquid phase. Only the smaller volume and highly enriched CO 2 rich phase needs to be heated and regenerated, which greatly reduces the amount of heating liquid, thereby significantly reducing the regeneration energy consumption and improving operation efficiency. Systematic research on ionic liquids as phase separation regulators in the current industry is relatively scarce. Traditional phase change systems have defects such as unstable phase separation, poor adaptability to working conditions, and insufficient thermal stability. The 1-butyl-3-methylimidazolium tetrafluoroborate (BF) ionic liquid has excellent thermal stability, good gas-liquid permeability and selective adsorption performance of CO 2, which can effectively regulate the phase structure of aqueous solutions and optimize intermolecular forces. It provides an excellent foundation for the construction of high-performance and low-energy MEA-ILs-water three-phase composite absorption systems.

Based on the advantages of technical bottlenecks and material characteristics in the above industries, the research team of Jiang Jianguo of Tsinghua University innovatively developed the MEA-BF aqueous two-phase solvent system and constructed a new low-energy biogas CO ² capture and biogas upgrade process. The team systematically explored the physical parameters of the mixed solvent, phase separation characteristics, CO2 capture performance, biogas purification effect and energy consumption law of regeneration, combined with nuclear magnetic characterization and quantum chemical calculation to reveal the microscopic reaction mechanism, providing a complete theoretical support and experimental basis for the industrialization of ionic liquid phase change absorption technology. Based on the technical bottlenecks and material characteristics advantages in the above industries, the research team of Jiang Jianguo of Tsinghua University innovatively developed the MEA-BF aqueous two-phase solvent system and constructed a new low-energy biogas CO ² capture and biogas upgrade process. The team systematically investigated the physical parameters of the mixed solvent, the phase separation characteristics, the carbon dioxide capture performance, the purification effect of biogas, and the energy consumption law of regeneration. Combined with nuclear magnetic characterization and quantum chemical calculation, the microscopic reaction mechanism was revealed, providing a complete theoretical support and experimental basis for the industrialization of ionic liquid phase change absorption technology.

2. Construction of a new MEA-BF biphasic solvent system 2. Construction of a new MEA-BF biphasic solvent system

The MEA-BF biphasic aqueous solution system constructed in this study is a composite functional phase change absorption system with monoethanolamine (MEA) as the main absorber of CO 2, 1-butyl-3-methylimidazolium tetrafluoroborate (BF) ionic liquid as the phase separation regulator and performance modifier, and pure water as the viscosity regulator. MEA is responsible for rapidly capturing CO _ 2 in biogas through chemical adsorption to ensure efficient decarbonization efficiency; BF ionic liquids do not directly participate in CO _ 2 chemical reactions, but mainly play the core role of phase regulation, improving system thermal stability, optimizing intermolecular forces, and reducing reaction energy barriers; clean water is used to reduce the overall viscosity of the system and enhance the efficiency of gas-liquid mass transfer. The three are synergistic and complementary, effectively making up for the inherent defects of a single MEA solvent and a single ionic liquid solvent. The MEA-BF dual-phase aqueous solution system constructed in this study is a composite functional phase change absorption system with monoethanolamine (MEA) as the main absorber of CO _ 2, 1-butyl-3-methylimidazolium tetrafluoroborate (BF) ionic liquid as the phase separation regulator and performance modifier, and pure water as the viscosity regulator. MEA is responsible for rapidly capturing CO 2 in biogas through chemisorption to ensure efficient decarbonization efficiency; BF ionic liquids do not directly participate in CO 2 chemical reactions, but mainly play the core role of phase regulation, improving system thermal stability, optimizing intermolecular forces, and reducing reaction energy barriers; clean water is used to reduce the overall viscosity of the system and enhance the efficiency of gas-liquid mass transfer. The three are synergistic and complementary, effectively compensating for the inherent defects of a single MEA solvent and a single ionic liquid solvent.

Compared with the traditional single 30% MEA aqueous solution system, the new two-phase system perfectly combines the advantages of high absorption rate of amine liquid and low volatilization of ionic liquid, and stable hot topic. At the same time, it relies on the phase change characteristics to achieve a new process mode of "rich-phase centralized regeneration and poor-phase direct circulation", which greatly reduces regeneration energy consumption from the process level and solves the industry problems of high energy consumption, large solvent loss and serious equipment corrosion in traditional processes. Compared with the traditional single 30% MEA aqueous solution system, the new two-phase system perfectly combines the advantages of high absorption rate of amine liquid and low volatilization of ionic liquid, and stable hot topic. At the same time, it relies on the phase change characteristics to achieve a new process mode of "concentrated regeneration of rich phase and direct circulation of poor phase", which greatly reduces regeneration energy consumption from the process level and solves the industry problems of high energy consumption, large solvent loss and serious equipment corrosion in traditional processes.

3. Experimental results and comprehensive performance analysis 3. Experimental results and comprehensive performance analysis

The research team systematically tested the physical characteristics, biogas upgrade effect, phase separation performance and regeneration energy consumption of the mixed solvent by adjusting the mass ratio of different MEA and BF, and clarified the optimal process ratio and performance change law. The experimental results have strong engineering guidance value. The research team systematically tested the physical characteristics, biogas upgrade effect, phase separation performance and regeneration energy consumption of the mixed solvent by adjusting the mass ratio of different MEA and BF, and clarified the optimal process ratio and performance change law. The experimental results have strong engineering guidance value.

In terms of the purity of biogas purification, the amount of BF added has little effect on the purity of methane after the upgrade, and all the proportioning systems can stably produce high-purity biomethane that meets the quality standards of pipeline network transportation and vehicle gas. Among them, in terms of the purity of biogas purification, the amount of BF added has little effect on the purity of methane after the upgrade, and all the proportioning systems can stably produce high-purity biomethane that meets the standards of pipeline network transportation and vehicle gas. Among them, the 30%MEA-40%BF30%MEA-40%BF quality proportioning system has the best comprehensive performance and is the optimal industrial proportioning scheme for this process.

In terms of solvent physical properties, the density and viscosity of the mixed solution show a steady upward trend with the increase of BF ionic liquid content. When the BF mass fraction is controlled within 50%, the viscosity of the system remains at a low level, the gas-liquid mass transfer resistance is small, the fluid flow performance is excellent, and it is suitable for the working conditions of the existing industrial desulfurization and decarbonization equipment. However, when the BF content exceeds 60%, the viscosity of the system rises sharply, which will greatly hinder the gas-liquid contact and mass transfer process, increase the energy consumption of equipment transportation, and is no longer suitable for industrial phase change separation system. This conclusion clarifies the safe and controllable range of ionic liquid content. In terms of solvent physical properties, the density and viscosity of the mixed solution show a steady upward trend with the increase of BF ionic liquid content. When the BF mass fraction is controlled within 50%, the viscosity of the system is maintained at a low level, the gas-liquid mass transfer resistance is small, the fluid flow performance is excellent, and it is suitable for the working conditions of existing industrial desulfurization and decarbonization equipment. However, when the BF content exceeds 60%, the viscosity of the system rises sharply, which will greatly hinder the gas-liquid contact and mass transfer process, increase the energy consumption of equipment transportation, and is no longer suitable as an industrial phase change separation system. This conclusion clarifies the safe and controllable range of ionic liquid content.

In terms of phase separation and energy consumption performance, the optimal ratio of 30MEA-40BF aqueous solution can achieve stable two-phase stratification after absorbing CO 2. The volume of the carbon-rich phase after cracking only accounts for 50% of the total volume, and almost all CO 2 in the system is enriched in the rich phase. The poor phase is basically carbon-free and can be directly recycled. The traditional MEA process requires heating and regeneration of all the absorbed rich liquid, while the two-phase system only needs to process half the volume of rich phase liquid, which greatly reduces the amount of heating medium and thermal energy consumption. The measured data show that the regeneration energy consumption of this new system is higher than that of the traditional 30 wt% MEA aqueous solution process in terms of phase separation and energy consumption performance. After the optimal ratio of 30MEA-40BF aqueous solution absorbs CO2, a stable two-phase stratification can be achieved. After cracking, the volume of the carbon-rich phase only accounts for 50% of the total volume, and almost all CO2 in the system is enriched in the rich phase, and the poor phase is basically carbon-free and can be directly recycled. The traditional MEA process requires heating and regeneration of all the absorbed rich liquid, while the two-phase system only needs to process half the volume of rich liquid, which greatly reduces the amount of heating medium and thermal energy consumption. The measured data shows that the regeneration energy consumption of the new system is reduced by 43.19% and 43.19% compared with the traditional 30 wt% MEA aqueous solution process. The energy saving effect is extremely significant, and it perfectly solves the core pain point of the high energy consumption of the traditional amine method for decarbonization., The energy saving effect is extremely significant, and it perfectly solves the core pain point of the high energy consumption of the traditional amine method for decarbonization.

4. Microscopic reaction mechanism and intermolecular interaction mechanism 4. Microscopic reaction mechanism and intermolecular interaction mechanism

In order to determine the microscopic nature of the excellent performance of the two-phase system, the research team systematically revealed the reaction path, product distribution and intermolecular force mechanism of the system, and clarified the modification mechanism of ionic liquids. In order to determine the microscopic nature of the excellent performance of the two-phase system, the research team combined the ³ C NMR characterization, Gaussian quantum chemical calculation, Multiwfn and VMD three-dimensional visualization analysis to systematically reveal the reaction path, product distribution and intermolecular force mechanism of the system, and clarify the modification mechanism of ionic liquids.

The results of NMR characterization confirmed the precise distribution of the two-phase products: MEA parent, protonated amine, carbamate, carbonate and bicarbonate, etc., all of the CO2 absorption reaction products are enriched in the lower water-rich phase; while BF ionic liquid exists stably in the upper lean phase, does not participate in chemical reactions, does not regenerate with the rich phase loss, can be recycled stably for a long time, and greatly reduces the cost of solvent supplementation. With the continuous increase of CO2 adsorption load in the system, the concentration of reaction products continues to increase, and the water solubility of the products is significantly enhanced. The system as a whole shows a stable trend of enrichment of reaction products to the aqueous phase, and the phase stratification state is clearer and more stable. The results of NMR characterization confirmed the precise distribution of the two-phase products: MEA matrix, protonated amine, carbamate, carbonate and bicarbonate, etc., all of the CO2 absorption reaction products were enriched in the lower water-rich phase; while BF ionic liquid stably existed in the upper lean phase, did not participate in chemical reactions, and did not lose with the regeneration of the rich phase. It could be recycled stably for a long time, greatly reducing the cost of solvent supplementation. With the continuous increase of CO 2 adsorption load in the system, the concentration of reaction products continued to increase, and the water solubility of the products was significantly enhanced. The system as a whole showed a stable trend of enrichment of reaction products to the aqueous phase, and the phase stratification state was clearer and more stable.

Quantum chemical calculation results further clarify the strengthening mechanism of ionic liquids: The solvent effect of BF ionic liquids can effectively reduce the reaction energy barrier of the chemical reaction between MEA and CO2, accelerate the gas-liquid mass transfer and adsorption reaction process, and improve the absorption rate and adsorption efficiency of CO 2O without changing the reaction products. Intermolecular force analysis shows that the molecular interaction of the two-phase system is mainly dominated by van der Waals force and hydrogen bond. The anions and cations of the ionic liquid can produce extremely strong van der Waals interactions within a reasonable ratio range, stabilize the two-phase structure of the system, and ensure the stability of phase separation. At the same time, it was found that the final two-phase stratification position of the system and whether the phase state was reversed or not depended on the total amount of product generated by the CO2 absorption reaction, and the concentration of the product was the key core parameter that regulated the phase separation morphology. The quantum chemical calculation results further elucidated the enhancement mechanism of ionic liquids: the solvent effect of BF ionic liquids can effectively reduce the reaction energy barrier of MEA and CO 2O chemical reaction, accelerate the gas-liquid mass transfer and adsorption reaction process, and improve the CO2 absorption rate and adsorption efficiency without changing the reaction products. The analysis of intermolecular forces shows that the molecular interaction of the two-phase system is mainly dominated by the van der Waals force and the hydrogen bond. Ionic liquid anions and cations can produce extremely strong van der Waals interactions within a reasonable ratio range, stabilizing the two-phase structure of the system and ensuring the stability of phase separation. At the same time, the study found that the final two-phase stratification position of the system and whether the phase state is reversed or not depend on the total amount of products generated in the CO2 absorption reaction, and the product concentration is the key core parameter that regulates the phase separation morphology.

5. Study on the kinetic characteristics of phase separation 5. Study on the kinetic characteristics of phase separation

The response rate, stable time and enrichment efficiency of phase separation are the key indicators to determine the feasibility of the industrialization of the phase change absorption process. The team systematically investigated the phase separation kinetics of the MEA-BF dual-phase system under different CO2 loading conditions, and clarified the influence law of the operating conditions parameters on the delamination effect. The response rate, stable time and enrichment efficiency of the phase separation are the key indicators to determine the feasibility of the industrialization of the phase change absorption process. The team systematically investigated the phase separation kinetics of the MEA-BF dual-phase system under different CO2 loading conditions, and clarified the influence law of the operating conditions parameters on the delamination effect.

The experimental results show that the higher the initial CO2 load of the system, the shorter the stability time of the two-phase rapid stratification, the faster the phase separation response speed, and it is suitable for the rapid processing requirements of industrial continuity. In the full range of experimental conditions, the volume of the carbon-rich phase after stratification is always stable at about 50% of the total volume, the phase structure is uniform, the repeatability is good, and it has extremely strong working condition stability. When the CO _ 2 load reaches the industrial common working conditions of 0.5 mol CO _ 2/mol amine, the carbon enrichment rate of the system can reach more than 95%, and most of the CO _ 2 is concentrated in the lower rich phase, and the phase separation efficiency and carbon enrichment accuracy meet the requirements of high industrial standards. The experimental results show that the higher the initial CO2 load of the system, the shorter the stability time of the two-phase rapid delamination, the faster the phase separation response speed, and the rapid processing demand of industrial continuity. In the full range of experimental conditions, the volume of the carbon-rich phase after delamination is always stable at about 50% of the total volume, and the phase structure is uniform and reproducible, which has extremely strong working condition stability. When the CO _ 2 load reaches the common industrial conditions of 0.5 mol CO _ 2/mol amine, the carbon enrichment rate of the system can reach more than 95%. Most of the CO _ 2 is concentrated in the lower rich phase, and the phase separation efficiency and carbon enrichment accuracy meet the requirements of high industrial standards.

From the microscopic process of phase separation, the water-soluble products such as carbamate and carbonate generated by the absorption reaction drive the aqueous solution phase to sink down, forming a high-density carbon-rich phase; while BF ionic liquid, with its unique hydrophobic and phase separation characteristics, carries part of the free water to migrate up, forming a low-density carbon-poor phase. In the process of stratification dynamics, the rich phase movement is mainly dominated by gravity and intermolecular forces, and the sedimentation trend is stable; the poor phase is mainly affected by fluid resistance and buoyancy. The stratified interface is clear, no miscibility, and no emulsification. The system has strong anti-interference ability and is suitable for long-term continuous cycle operation. From the perspective of the microscopic process of phase separation, the water-soluble products such as carbamate and carbonate generated by the absorption reaction drive the aqueous solution phase to sink down, forming a high-density carbon-rich phase; while BF ionic liquids, with their unique hydrophobic and phase separation characteristics, carry part of the free water upward to migrate, forming a low-density carbon-poor phase. In the process of stratification dynamics, the rich phase movement is mainly dominated by gravity and intermolecular forces, and the sedimentation trend is stable; the poor phase is mainly affected by fluid resistance and buoyancy. The stratification interface is clear, miscible, and emulsified. The system has strong anti-interference ability and is suitable for long-term continuous cycle operation.

6. Comprehensive research conclusion and industrial application value 6. Comprehensive research conclusion and industrial application value

Comprehensive experimental data and mechanism analysis, MEA-BF ionic liquid aqueous two-phase solvent system realizes the advantages and disadvantages of traditional amine method and ionic liquid technology, and constructs a set of high-efficiency, low-energy, high-stability, and recyclable biogas CO ² capture and biomethane upgrade new technologies. The system completely retains the advantages of MEA's fast absorption rate, high decarbonization accuracy, and wide adaptability. At the same time, it inherits the characteristics of low volatilization, stable hot topic, corrosion resistance, and recyclability of ionic liquids, and completely solves the shortcomings of traditional MEA process with high regeneration energy consumption, large solvent loss, and poor thermal stability. Based on experimental data and mechanism analysis, MEA-BF ionic liquid aqueous two-phase solvent system realizes the advantages and disadvantages of traditional amine method and ionic liquid technology, and constructs a set of high-efficiency, low-energy, high-stability, and recyclable biogas CO ² capture and biomethane upgrade technologies. The system completely retains the advantages of fast MEA absorption rate, high decarbonization accuracy, and wide adaptability. At the same time, it inherits the characteristics of low volatilization, stable hot topic, corrosion resistance, and recyclability of ionic liquids, and completely solves the shortcomings of traditional MEA process with high regeneration energy consumption, large solvent loss, and poor thermal stability.

In terms of process performance, the system can stably prepare high-purity biomethane, meeting commercial gas standards; the phase separation is stable and controllable, the carbon enrichment rate exceeds 95%, only half-volume rich phase regeneration is required, the energy saving range exceeds 43%, and the energy saving and economic benefits are significant; ionic liquids do not participate in the reaction, have no loss, and can be recycled for a long time, which greatly reduces the cost of solvent operation and maintenance. In terms of operation stability, the system has controllable viscosity, high mass transfer efficiency, excellent thermal stability, and no emulsification and phase mixing problems. It is suitable for large-scale and continuous industrial biogas upgrading production lines. In terms of process performance, the system can stably prepare high-purity biomethane, meeting commercial gas standards; the phase separation is stable and controllable, the carbon enrichment rate exceeds 95%, only half-volume rich phase regeneration is required, the energy saving range exceeds 43%, and the energy saving and economic benefits are significant; ionic liquids do not participate in the reaction, have no loss, can be recycled for a long time, and greatly reduce the cost of solvent operation and maintenance. In terms of operation stability, the system has controllable viscosity, high mass transfer efficiency, excellent thermal stability, and no emulsification mixing problems. It is suitable for large-scale and continuous industrial biogas upgrading production lines.

From the perspective of industry value, this research innovates the ionic liquid phase separation regulation mechanism, verifies the application potential of BF ionic liquid in the field of low-energy biogas phase change decarbonization for the first time, and provides a new technical path for carbon capture scenarios such as biogas purification, industrial flue gas decarbonization, and synthesis gas refining. The technology takes into account environmental protection, economy and stability, and effectively breaks the industrialization bottleneck of high energy consumption and high cost of traditional carbon capture technology. It provides important technical support for the large-scale utilization of biomass energy and the landing of dual-carbon targets. It has extremely high engineering promotion value and industry innovation significance. From the perspective of industry value, this research innovates the ionic liquid phase separation regulation mechanism, verifies the application potential of BF ionic liquid in the field of low-energy biogas phase change decarbonization for the first time, and provides a new technical path for carbon capture scenarios such as biogas purification, industrial flue gas decarbonization, and synthesis gas refining. The technology takes into account environmental protection, economy and stability, effectively breaks the industrialization bottleneck of high energy consumption and high cost of traditional carbon capture technology, and provides important technical support for the large-scale utilization of biomass energy and the landing of dual carbon targets. It has extremely high engineering promotion value and industry innovation significance.