[DETAH][Tz]/1-propanol/H₂O Biphasic Solvent For CO₂ Capture

The conventional amine based biphasic solutions have outstanding characteristic of low regeneration duty,but they encounter drawbacks such as high viscosity of rich liquid and low regeneration efficiency.Amino functionalized ionic liquid biphasic solvent can effectively make up for the deficiency of the amine based biphasic solutions,but it has some disadvantages such as low absorption load and large solvent loss during regeneration.The amino-azolyl functionalized ionic liquid biphasic solvent have the advantages of the first two kinds of biphasic solvent.It contains active groups,which not only ensures the CO₂ absorption molar ratio of 1:1,but also promote the regeneration of biphasic solvent.Therefore,while ensuring good phase separation characteristics and absorption performance,this type of absorbent will also have the advantages of low viscosity of rich liquid,high regeneration efficiency and low solvent loss.In this thesis,[DETAH][Tz]was selected as the main absorbent and mixed with 1-propanol/water to construct a new biphasic solvent（labelled as[DETAH][Tz]/Pro H/H₂O）for CO₂ capture.In this work,absorption-desorption characteristic was investigated.¹³C NMR and quantum chemistry calculation were used to investigate the reaction mechanism and phase transformation mechanism.Finally,kinetics and regeneration duty were studied.The main contents of this study are as follows:（1）The results of CO₂ absorption-desorption performance showed that the[DETAH][Tz]/Pro H/H₂O biphasic solvent composed of 50 v/v%1-propanol had good phase separation,absorption performance(1.71 mol CO₂·mol^-1absorbent)and the viscosity of rich liquid phase（2.57 m Pa·s）.The good phase separation characteristics of the absorbent were as follows:The rich liquid loading accounted for 96%of the total CO₂ loading and 44%of the total volume.Using 1-propanol as a regenerative promoter,the regeneration efficiency of the rich liquid kept above 90%after five regeneration cycles,which indicated that the biphasic solvent had good reusability.（2）¹³C NMR was used to analyze the products of the system in the process of absorption and desorption of CO₂,and elucidated the reaction mechanism.In the absorption process,both the anion and cation in[DETAH][TZ]reacted with CO₂ to form carbamate（RNCOO^-）,which ensured the absorption performance of the absorbent.[Tz]^-was protonated to form[Tz]-H and 1-propanol promoted the RNCOO^-decomposition,which could enhance the regeneration of the the rich liquid.In addition,absorption and desorption were inverse processes.（3）The phase separation mechanism was clarified by experiment combined with quantum chemistry calculation.The results showed that hydrogen bond interaction was the main interaction between CO₂ products and solvent molecules（H₂O and 1-propanol）.The length of hydrogen bond and relative polarity difference between products and solvents dramatically affect the distribution of CO₂ products in the solvents.The high-density CO₂ products had high polarity and were water-soluble,forming a CO₂ rich liquid in the lower aqueous solution.While the CO₂ lean liquid of1-propanol floats in the upper because it was less dense than water.Thus the liquid-liquid transformation process occurred.（4）The kinetics and regeneration duty evaluation of[DETAH][Tz]/Pro H/H₂O.The result showed the addition of 1-propanol promoted the dissolution of CO₂ and greatly reduced the activation barrier of[DETAH][Tz]/Pro H/H₂O.The regeneration duty of[DETAH][Tz]/Pro H/H₂O(1.99 GJ·ton^-1 CO₂)was 47.63%lower than that of the conventional MEA(3.80 GJ·ton^-1 CO₂).Therefore,[DETAH][Tz]/Pro H/H₂O had industrial application.