Preparation Of Hybrid Membranes Based On Imidazole Quaternary Ammonium Fillers And Application For CO₂ Separation

Membrane technology has a broad application prospect in the field of gas separation as an efficient,economical,convenient and clean separation technology.Developing CO₂ separation membranes with low-cost and high-selectivity become a research focus nowadays.Polyelectrolyte is hydrophilic,easy crosslinking,and has a superior solubility mechanism in spite of its crystal trend,which has a good development prospect.It always appears a trade-off effect between the gas permeation and selectivity in the traditional polymer membranes,which transmittion is based on dissolution-diffusion mechanism Without introducing the alkaline carriers,this study uses sulfonated poly ether ether ketone for the polymer matrix while functional nanostructures such as halloysite nanotubes and graphene oxide are used to control the structure of polymer membranes by adopting a hybrid approach.Two types of hybrid membranes were designed and prepared and expect that CO₂could be transmitted in the form of ions.Through a series of structural characterizations and performance tests,the effects of water and ions as well as the transfer mechanism in the hybrid membranes were investigated under humidified conditions.The specific contents and conclusions in this study are lisited as follows:?1?Preparation of quaternized imidazole functionalized HNTs and study on the gas performance of hybrid membranes:Inspired by the excellent OH^-transmission of alkaline membranes in fuel cells,quaternized imidazole brushes were grafted onto halloysite nanoparticles.The inorganic nanoparticles was introduced into a sulfonated poly ether ether ketone material,and initially explored the ion exchange for gas transmission.The experiment showed that the 7.5%-C₄-VI-mHNTs/SP hybrid membrane was reached 162 barrer for CO₂ permeation while the selectivity reached20 at a temperature of 65°C,1 bar for pressure,which permeation was increased by80%compared with the pure membrane,however,its selectivity was still not satisfactory.?2?Preparation of quaternized imidazole functionalized GO and study on the gas performance of hybrid membranes:In order to improve the selectivity of gas membranes,C₄-VI-MGO/SP was introduced into SPEEK membranes for constructing a transmission channel based on“ion exchange”.The quaternized imidazole-modified GO mainly has the following advantages:?i?Graphene oxide is a two-dimensional sheet material with a large aspect ratio,the introduction of GO makes the gas transmission path tortuous and complicated;?ii?The imidazole brush prepared by distillation-precipitation polymerization is embedded in the polymer matrix which has a large contact area with the polymer,and it is beneficial for the conduction of H⁺and HCO₃^-to achieve ion exchange;?iii?The imidazolium cation and the sulfonic acid anion could combinate with water respectively and forming a“salting-out effect”in the membrane which can increasing the gas selectivity.The imidazolium cation could promote ion transformation of the HCO₃^-,and the sulphonate anion could promote the proton transfer and increase the CO₂ permeation.With the two-pronged manner,the hybrid membranes prepared in this experiment has a good performance for gas separation.The CO₂ permeation reaches 329 barrer and the selectivity reaches 73under the pressure of 5 bar,which breaks the upper bound line revised in 2008 by Robeson.