Synthesis Of Mesoporous Molecular Sieve MCM-41 Based New Muilt-site Ionic Liquid Composites And Synergetic Capture CO₂

CO₂ is a main greenhouse gases,its emissions caused many adverse effects on the planet.Coal-fired power plants is one of the CO₂ gas emission sources.The research that CO₂ capture and separation technique of post-combustion of fossil fuels imposes vital significance on reducing the CO₂ emissions,slowing down the climate change and achieving sustainable economic development.Due to its non-volatile,good cycle stability and adjustable structure,ionic liquid was used for CO₂ capture.However,the high cost and viscosity hinder the efficent CO₂ absorption and limit industrial application.Thus the ionic liquid loaded on the inorganic porous material form immobilized ionic liquids more practical significance.In this paper,two type multi-site synergistic ionic liquids [P₄₄₄₄][2-Op] and [N₄₄₄₄][2-Op] are synthesized and loaded on the porous silica MCM-41 and pore-expanded MCM-41 via impregnation-evaporation method,forming the composite materials that possessed the higher CO₂ uptake,better cycle stability and faster adsorption.Main research contents and conclusions are summarized as followings:?1?The tetrabutyl phosphonium hydroxide or tetrabutyl ammonium hydroxide is used as cation,2-hydroxy pyridine is used as anion for synthesizing new multi-site functionalized ionic liquid [P₄₄₄₄][2-Op] and [N₄₄₄₄][2-Op].The structure of materials were characterized by infrared?IR?and nuclear magnetic resonance?NMR?,which confirmed that the formation of [P₄₄₄₄][2-Op] and [N₄₄₄₄][2-Op].?2?Ionic liquid [P₄₄₄₄][2-Op] with different mass are immobilized into the channel of the molecular sieve MCM-41 via the facile impregnation-evaporation method to prepare composite materials PM-ws.The pore structure,physical and chemical properties,thermal stability and CO₂ adsorption performance of composite materials are systematically studied.The results showed that after the loading of ionic liquid,orderly hexagonal structure of mesoporous MCM-41 is still remained.Composite materials PM-5 possessed high thermal stability up to 420 °C.?3?The influence of loading amount of ionic liquid,adsorption temperature and CO₂ partial pressure on CO₂ capture are invastigated.The results indicate that CO₂ adsorption capacity of samples first increases and then decreases with increasingly loading of ionic liquid.Sample PM-5 shows the highest CO₂ adsorption capacity 1.21 mmol/g within 5 minutes.In addition,after ten cycles,96% of the initial CO₂ uptake was obtained,showing excellent cycle stability.Low temperature and high partial pressure are good for CO₂ adsorption.?4?The pore-expanded structural MCM-41?PE-MCM-41?was synthesized for supporting multi-site functional ionic liquid [P₄₄₄₄][2-Op] and [N₄₄₄₄][2-Op] to form composite material PE-MP-ws and PE-MN-ws.Composite PE-MP-5 is still stable at 420 °C,and PE-MN-5 to PE-MN-15 could be stable at 166 °C.Additionally,PE-MCM-41 with a larger pore size and pore volume is beneficial to load ionic liquids and keep a larger pore structure for CO₂ adsorption.The CO₂ adsorption capacity of PE-MP-10 and PE-MN-15 were calculated as 1.66 mmol/g and 1.08 mmol/g,respectively.?5?After ten cycles,91% and 89% of PE-MP-10 and PE-MN-15 initial value are kept respectively,showing the good cycle stabitity.