Study On Preparation Of Terminal Amino Polyether And Its Absorption And Desorption Of Carbon Dioxide By Leaving Group Method

To solve the greenhouse effect caused by high CO2 emissions, chemical absorbents such as organic alcohol amine are widely applied in CO2 capture and storage (CCS) technology. However, the technical bottleneck of high energy consumption has become an obstacle to promote this technology on a large scale. Therefore, looking for a new low-energy desorbed chemical solvent is of great urgency. In this study, the polyethylene glycol, benzene sulfonyl chloride and organic amine are used as starting materials, characterized by using IR and HNMR and optimized for reaction conditions, so that an amine-terminated polyether (ATPE) with thermally induced phase separation property is synthesized; its phase separation temperature is measured, and the end product’s performance in absorbing and desorbing CO2 and relationship between end product and phase separation temperature are studied. The contents and conclusions are as follows:1. When synthesizing ATPE with leaving group method, the trimethylamine has a better effect than the pyridine as the acid binding agent and organic solvent, but the determination of spectra peak is affected by the difficult separation of its product from trimethylamine, therefore the pyridine is selected as the reaction solvent; in order to ensure that the hydroxyl at both ends of the polyethylene glycol is completely substituted by the benzenesulfonyl, the initial ratio of polyethylene glycol to benzene sulfonyl chloride is determined as 1:3, and the initial ratio of intermediate product to organic amine is also determined as 1:3 so as to ensure that the intermediate product is completely reacted.2. The thermally induced phase separation temperature of ATPE synthesized with different molecular-weight polyethylene glycol and organic amine as starting materials decreases with an increase of the polyether chain; only ATPE water solution synthesized with the polyethylene glycol 800 and n-butylamine as starting materials can achieve liquid-liquid phase separation at 80 ℃; impurities shall be avoided as they have a certain influence on the thermally induced phase separation temperature of ATPE water solution.3. By comparing loading data of MEA obtained with this experimental device at 40℃ and 80℃ with classic reference data provided by Jong I. Lee and Alan E. Mather, experimental data show that the reaction kettle used in this experiment is reliable when calculating the loading of CO2 in the organic amine solution and original experimental data obtained with this experimental device is accurate.4. Use synthesis of ATPE preparation of measuring concentration of 30% of the absorber in the 40-120℃, found with thermally induced phase separation properties of absorber in the same temperature and CO2 partial pressure conditions, CO2 desorption was significantly higher than that of no heat and phase properties of the absorber to verify the speak proposed with thermal induced phase separation properties of chemical absorbent under low temperature strengthening solvent desorption properties of CO2 and ultimately to reduce the chemical absorption process energy consumption.5. D-type ATPE water solution becomes turbid as the solubility decreases with an increase of temperature. D-230 and D-400 are all primary alcohol amine absorbent with amino functional group. As the number of amino per mole is twice as MEA, the corresponding CO2 mole loading is greater than 1 and nearly twice as MEA, its CO2 loading is equivalent to MEA as ATPE synthesized in the experiment contains impurities without purification although it contains the double-ended amino.6. During the test of measuring the absorption and desorption performance of CO2, the degradation fails as the alcohol amine absorbent is susceptible to temperature change when exposed in the air. Therefore, solvents used in the test are preserved under dark condition and isolated from air.