负载型氨基功能化离子液体吸附CO_2性能差异研究

CO_2 Adsorption Studies in Supported Amino Functionalized Ionic Liquids

以Al2O3、SiO2和活性炭为载体,采用浸渍法制备了负载型离子液体([NH2p-mim]X:X=Br-,PF6-,BF4-,NTf2-)CO2吸附剂,利用红外光谱(FT-IR)、元素分析(EA)、热重差热分析(TG-DTA)等技术对负载型离子液体进行了表征研究.室温下考察了负载型离子液体吸附CO2的性能,研究了载体的性质、离子液体的物化性质对负载型离子液体吸附CO2性能的影响.结果表明,以Al2O3为载体的负载型离子液体展现出比以SiO2和活性炭为载体更为优异的吸附CO2性能.红外表征结果表明,载体Al2O3对离子液体良好的分散作用以及载体Al2O3与离子液体之间较弱的相互作用,增加了负载后的离子液体吸附CO2的活性位.同时,Al2O3负载型离子液体-NH2上N原子电子云密度相对较大,有利于CO2与之作用.Al2O3负载型离子液体对CO2的吸附容量随离子液体黏度的增大而增大,随离子液体体积的增大而减小.

In this paper, in order to study the potential impact of supported ionic liquids on CO2 adsorption, the specific ionic liquids （[ NH2p-mim] X：X = Br-,PF6-, BF4-, NTf2-） were immobilized in different supports, such as active carbon （AC）, silica （SiO2 ） and alumina（Al2O3 ） via an impregnation-vaporization method. The supported ionic liquids were characterized by flourier transform infrared （FI＇-IR） spectrometry, elemental analysis （ EA ）, thermogravimetry- differential thermal analysis （ TG- DTA ） and so on. The performance of supported ionic liquids for CO2 adsorption were investigated, and the effects of using supports with different chemical structures and different anions on the CO2 adsorption capacity of supported ionic liquids have been studied. The results show that the supported ionic liquids prepared with Al2O3 exhibits a high affinity for CO2 compared with those on SiO2 and AC. FT-IR analysis indicates that this behavior is due to the excellent dispersing effect of supports on the ionic liquids and the weak interaction between ionic liquids and supports, the latter increases the active sites of ionic liquids for CO2 adsorption after being loaded. The supported ionic liquids prepared with Al2O3 have a relatively large electron density of atomic N of amino, which is favourable to the reaction of CO2 with - NH2 of [ NH2p-mim] [ Br]/Al2O3. The CO2 adsorption performance of supported ionic liquids increases with the increase of the viscosity of ionic liquids and reduces with the increase of volume of ionic liquids.