表面活性剂修饰对MCM-41负载离子液体吸附CO_2影响的研究

The Effect of Surfactant Modification of MCM-41 on Supporting Ionic Liquid for CO_2 Adsorption

以表面活性剂修饰的MCM-41为载体,采用浸渍法制备了负载离子液体[NH2p-mim][PF6]的二氧化碳吸附剂,考察了表面活性剂对离子液体在MCM-41上分散的影响以及所导致的CO2吸附性能的变化.利用红外光谱(FT-IR),X-射线衍射(XRD),高分辨透射电子显微镜(HRTEM),热重分析(TG)技术对所合成的负载型离子液体吸附剂进行了表征研究,并与其吸附CO2的性能变化、离子液体与表面活性剂相互作用方式等因素进行了关联.结果表明:MCM-41负载离子液体后对CO2的吸附性能略有提高,而经表面活性剂修饰的MCM-41负载离子液体后,对CO2的吸附容量较载体本身提高了2.5倍.这一方面是因为表面活性剂胶束改善了MCM-41上离子液体的分散性,另一方面是表面活性剂胶束对离子液体分子上电荷分布的影响,导致离子液体内部阴阳离子之间的相互作用减弱,从而引起离子液体中-NH2上N原子电子云密度增大,使其与CO2作用更容易.CO2在经表面活性剂修饰后的MCM-41负载离子液体[NH2p-mim][PF6]吸附剂上的吸附受扩散控制,其吸附-脱附CO2所需能量较小,经过5次吸附-脱附循环后,其吸附性能仍保持稳定.热重分析结果表明,经表面活性剂修饰后的MCM-41负载离子液体吸附剂在100℃下氮气气氛再生时不会发生性质改变.

A new CO2 adsorbent was synthesized by incorporating the ionic liquid（） into surfactant-modified MCM-41.The effect of surfactant modification on the ionic liquid dispersion and the changing of CO2 adsorption performance of supported ionic liquid were investigated.The supported ionic liquids were characterized by Flourier transform infrared（FTIR） spectra,X-ray diffraction（XRD）,N2 adsorption/desorption technologies and thermogravimetric（TG） annlysis.The performance for CO2 adsorption of supported ionic liquids and the interaction between surfactant and were associated to these characterization results.The results show that the CO2 adsorption capacity of /MCM-41 increases slightly than that of MCM-41,however the adsorption capacity of / surfactant-modified MCM-41 was increased by 2.5 times compared with surfactant-modified MCM-41.This enhancement can be attributed to two reasons,one is the surfactant micelle can make the ionic liquid dispersion better,and another is surfactant micelle has an effect on the charge distribution of ionic liquid,which would lead to the decrease of the interaction of cation and anion and the increase of the electron density of N atomic of amino.Therefore,the reaction of CO2 with the-NH2 of /surfactant-modified MCM-41 took place more easily.It is known that the adsorption of surfactant-modified MCM-41 supported ionic liquid for CO2 is controlled by the diffusion of CO2,and the adsorption/desorption process need less energy,so the adsorption ability is stable after 5 cycles.The thermo gravimetric analysis proves that no changes would happen on / surfactant-modified MCM-41 when it was regenerated at 100 ℃ under N2 atmosphere.