不同有机胺修饰MCM-41的CO2吸附性能和热稳定性

将乙二胺(EDA,60 g/mol)、四乙烯五胺(TEPA,189 g/mol)和两种聚乙烯亚胺600(PEI600g/mol; PEI1800g/mol)分别负载在MCM-41上制备氨基功能化介孔材料,研究其对CO₂的吸附性能和热稳定性.结果表明,除了EDA-MCM41,其他三种材料随着胺分子量增大CO₂吸附性能下降,但是热稳定性却有所提高,其中,TEPA-MCM41的吸附容量最大,达到2.7 mmol/g.同时发现,乙二胺在制备过程中随溶剂挥发而难以完全负载在MCM-41上.在纯N₂气氛和再生温度100 ℃条件下,经10次循环实验后,TEPA-MCM41的吸附能力下降了7.4%,而PEI600-MCM41和PEI1800-MCM41吸附能力保持不变,且质量变化在1%以内,表现出良好的再生稳定性.采用80%CO₂/20%N₂对吸附饱和的材料进行再生,四种材料的再生温度将提高到160 ℃以上,高分子量PEI600-MCM41和PEI1800-MCM41相比于TEPA-MCM41具有更好的热稳定性.

CO2 adsorption properties and thermal stability of different amine-impregnated MCM-41 materials

The adsorption properties of CO₂ on MCM-41 mesoporous materials impregnated with ethylenediamine (EDA), tetraethylenepentamine (TEPA) and two kinds of polyethylenimines (PEI600 and PEI1800), respectively, were studied with mass spectrometry (MS) and thermogravimetry (TG) techniques. The sample obtained by impregnating EDA (EDA-MCM-41) showed a low CO₂ adsorption capacity due to the ready volatilization of EDA, while those samples prepared by TEPA (TEPA-MCM-41), PEI600 (PEI600-MCM-41) or PEI1800 (PEI1800-MCM-41) exbibit higher adsorption capacity and thermal stability although the adsorption capacity decreased with increasing molecular weight of amines. A maximum CO₂ adsorption capacity of 2.7 mmol/g was achieved on the TEPA-MCM-41 with 40% TEPA. When this sample was regenerated at 100 ℃ under pure nitrogen atmosphere, its CO₂ adsorption capacity was decreased by 7.4% after ten recycles in contrast to less than 1% for both PEI600-MCM-41 and PEI1800-MCM-41. However, when the regeneration atmosphere was changed to 80% CO₂/20% N₂, the regeneration temperature should be be increased to more than 160 ℃ for all the samples despite that PEI-MCM-41 showed high thermal stability than TEPA-MCM-41.