Development Of Novel Phase Change Solvents And Absorption-stripping Performance For CO₂ Capture

Post-combustion CO₂ capture is of great significance for reducing the global warming effect caused by greenhouse gas emissions.At present,the post-combustion capture method used in industry is mainly the chemical solvent absorption method（especially the amine method）.Traditional amine solutions have many problems,such as large energy consumption for desorption.Thus,it is extremely important to seek new chemical absorbents.In recent years,a large number of studies have found that phase change solvents can effectively reduce the energy consumption of CO₂ desorption and amine regeneration in CO₂ capture.Developing novel absorbents with good performance is important for the application of phase change solvents in CO₂ capture.Many studies have found that the sulfolane-based phase change absorbent can effectively reduce the energy consumption of CO₂ capture,but there are still some problems,such as low phase-changing point,high viscosity,and poor mass transfer.The main research contents are as follows.（1）This work developed a new sulfolane-based mixed amine absorbent,sulfolane/MEA/EAE solution,and the phase change behavior,and absorption-stripping performance was studied comprehensively,The phasechanging point of the sulfolane/MEA/EAE solution at different ratios after absorbing CO₂ was studied,and it was found that as the MEA/EAE ratio decreased,the phase-changing point continued to increase.The phasechanging point ranges from 0.2 to 0.47 mol/mol.When there is no MEA in the solution,the solution remains homogeneous after absorbing CO₂.In addition,comprehensively understand the phase change behavior,absorption performance and desorption performance of the sulfolane/MEA/EAE solutions with different ratios,the best ratio of 5M/3M/2M was screened out.This solution has a higher phase-changing point（0.32mol/mol）,desorption rate and stripped CO₂ amount,and be energy saving compared with traditional amine solutions.To a certain extent,it solves the problem of poor mass transfer performance of the sulfolane-based phase change absorbent due to its low CO₂ loading point.（2）In order to further solve the problem of low phase-changing point of sulfolane-based phase change absorbent,a novel sulfolane-based secondary amine absorbent,sulfol ane/2-methyl aminoethanol（MAE）solution was developed based on the structure-activity relationship.The effect of different sulfol ane/MAE ratios on its absorption-stripping performance and phase change behavior was studied in this work.The results show that compared with sulfolane/MEA solution,the optimal ratio of 4M/5M sulfolane/MAE solution has a higher phase change loading point（0.42mol/mol）and better absorption-stripping performance.Using NMR technology to explore and find that the upper phase was a CO₂-rich layer,the composition was mainly amine,and the lower phase was occupied by sulfolane.In addition,the absorption and desorption experiments at different temperatures show that relatively low temperatures（range from 110℃ to 120℃）were beneficial for CO₂ removal and energy saving.Finally,the absorption and desorption performance of 4M/5M sulfolane/MAE solution and 5M MEA,5M MAE and 5M/4M sulfolane/MEA solution were compared and studied.The 4M/5M sulfolane/MAE solution can save about 60%energy consumption for CO₂ stripping compared with the traditional 5M MEA aqueous solution,and the stripped CO₂ amount is similar to that of 5M MEA and 5M MAE solutions.