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Study Of The Coupling Process Of Amine-functionalized Ionic Liquids-membrane Contactor In The Separation Of CO2

Posted on:2017-02-12Degree:MasterType:Thesis
Country:ChinaCandidate:J WuFull Text:PDF
GTID:2271330485457959Subject:Environmental engineering
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At present, conventional chemical absorption based CO2 capture technology was widely expected to be the most effective approach to control CO2 emission from power stations in a short period. However, chemical absorption has several disadvantages such as low mass transfer efficiency, high energy compustion and absorption cost in CO2 removal as well as the operation problems of flooding, foaming, channeling and entrainment. Of which, CO2 absorption and desorption based on hollow fiber membrane contactors are reported to be a promising technology with good mass transfer performance of CO2 absorption and low energy intensity for CO2 desorption. However, how to choose suitable absorbents and maintain long-term operating stability are the main issues for CO2 membrane absorption andstripping.In this thesis, four amine ionic liquids were synthesized and characterized by Infrared and Raman spectroscopic measurements. The absorption capacity of CO2 for ILs aqueous solution was investigated. The dynamic viscosity was measured for ILs and ILS+CO2 as well. Ruslts show that amine-functionalized ILs show significantly high absorption capacity for CO2. The absorption capacity of ILs reached 1.25~1.63 mol CO2 per mol of ILs at room temperature. Specifically, the viscosities of the ionic liquids depend both on the nature of the anion and the cation, and values of viscosity were increased after CO2 absorption. Moreover, the most probable mechanism of interaction of CO2 with ILs was investigated using Infrared and Raman spectrum.Four amine ionic liquids were analyzed by CO2 membrane absorption and desorption screening experiments for selecting the most effective absorbents for CO2 membrane absoption/ stripping. The CO2 absorption experiments were conducted in a Polytetrafluoroethylene (PTFE) hollow fiber membrane contactor under various conditions:liquid flow rates, gas flow rates and flow concentration. Ruslts show that [TETA][HCOO] is mostly recommended for using in a PTFE hollow fiber membrane contactor. The overall mass transfer coefficient of [TETA][HCOO] is higher than other ILs and the secarbonization rate of TETA][HCOO] is up to 98.73%; [TETA][HCOO] is found to have relatively high cyclic capacity in mole CO2/ mol absorbent, its regeneration rate is 91% when the CO2 rich solvent was recycled at 70℃ and 20kPa.To better understand the long-term performance for CO2 absorption, wettability of PTFE membrane contactors in exposed to four ILs was studied. The experimental ruslts show that [TETA][HCOO] has less deformation of membrane than other absorbents. Subsequently, [TETA][HCOO] was chosen to investigate the performance for CO2 absorption with the time. The overall mass transfer coefficient declines with time and reduces 34.87% after ooperating 110 hours.
Keywords/Search Tags:carbon dioxide, PTFE membrane contactor, membrane absorption, regeneration, membrane wetting
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