Experimental Study And Gaussian Simulation On The Structureactivity Relationship Of Chemical Structures Of Amine And CO₂ Capture Performance For CO₂ Absorption Into Amine Solutions

The rapid reduction of greenhouse gas emissions is recognized as necessary to mitigate the potential climate effects from global warming.The post combustion capture and storage is a key technology needed to achieve effective reductions of CO₂produced from the use of fossil fuels for electricity generation.Chemical absorption,especially amine scrubbing is the most mature and widely used post-combustion capture technology?PCC?,but the high energy consumption and poor chemi cal stability of amine solution restrict its further large-scale industrial application.In order to capture CO₂ with high efficiency and low energy consumption,the structure-activity relationship between the CO₂ absorption and desorption performance and amines with different molecular structures was tested by rapid fast screening method and Gaussian simulation,the main jobs and points of this paper are as follows:?1?The structure-activity relationship of MEA and eleven diamines was investigated by the rapid fast screening method.The effects of methyl,ethyl,hydroxyl groups,and distance between N groups in molecular structures on CO ₂absorption and desorption performance were evaluated.Experimental results r evealed that the proper number of methyl groups and ethyl groups on N atom could improve the absorption rate as well as the cyclic CO₂ capacity,and the addition of a hydroxyl group actually achieved a lower energy requirement for solvent regeneration with the decreasing stability of carbamate.In addition,the diamine with a hydroxyl group is more favorable for good stability in regeneration process,which addresses the problem of solvent loss in the application of diamines.Chain length extension in diamine can result in the poorer stability of the carbamate,its cyclic CO₂ capacity has been improved.?2?The relative Gibbs free energy of different diamines was simulated by using the Gaussian software.The effects of different substituents and carbon chain length on the relative Gibbs free energy were investigated.The results showed that if the high relative Gibbs free energy was achieved,the carb amate will become more unstable and the absorption process will be more efficient.At the same time,the relationship between relative Gibbs free energy and cyclic CO₂ capacity was discussed.It was found that the variation of Gibbs free energy was consist ent with that of cyclic CO₂ capacity,which indicated that the simulation and screening results were consistent.?3?Absorption and desorption performance of tertiary amines with dif ferent molecular structures was studied by rapid fast screening method.The effects of chain length,different numbers of hydroxyl and hydroxyethyl substitution on N atom,methyl side chain and alkyl substitution on N atom were investigated.The experimental results showed that the absorption and desorption performance of tertiary amine was weaken when the main chain length increases,so the cyclic CO₂capacity was also decreased.What's more,the cyclic CO₂ capacity of tertiary amine which has two methyl substituted on N atom is better than that with two ethyl substituted on N atom.It was also found that the absorption rate of tertiary amine with polyhydroxy was decreased,and its cyclic CO₂ capacity is slightly lower than that with monohydroxy substituted.When the number of hydroxyethyl group on N atom increased,its absorption rate and cyclic CO₂ capacity were decreased gradually.?4?The enthalpy change of reaction of different tertiary amines was simulated by using the Gaussian software,the tertiary amine with larger enthalpy change could show better desorption performance.The effects of chain length,methyl side chain,different numbers of hydroxyl and hydroxyethyl substitution on the enthalpy change of reaction were analyzed in the simulated calculation.The relationship between the enthalpy change of reaction and the average desorption rates?relative desorption energy consumption?of tertiary amines in the rapid screening experiment was also studied.The simulated results showed that the enthalpy change of reaction well predicted the trend of average desorption rates of tertiary amines,the reliability of the simulation results is verified.