Construction Of Ionic Environment In Poly(Ionic Liquid)s And Influence On Catalytic Performance

Although polymerized ionic liquids have received extensive attention and research in the field of catalysis,the strategy of designing efficient polymerized ionic liquids catalysts remains a great challenge.In particular,how the ionic environment in the polymerized ionic liquid affects the reaction and how to regulate the ionic microenvironment remains to be studied.Starting from binary mixed ionic liquid（DSILs）,this paper regulates the ionic environment by adjusting the cation structure and proportion,and confirms the influence rule of hydrogen bond and charge density of DSILs on hydrogen bond donor ability,hydrogen bond acceptor ability,polarity and acid-base properties of the reaction system.DSILs showed controllable and high activity in the ring-opening coupling reaction of propylene oxide and methanol.The Kamlet-Taft linear solvent energy equation was modified by adding an acid-base term,and the quantitative relationships among acid-base properties,hydrogen bond,polarity and catalytic performance were established,which provided theoretical guidance for rational design of ionic liquid catalysts.A series of highly efficient poly（ionic liquid）s catalyst with different ionic ratio were synthesized and the effect of ionic rates on the coupling reaction of propylene oxide with CO₂ or methanol was studied.Quaternization effectively controlled the ionic ratio and charge distribution of the poly（ionic liquid）s,which affected the microstructure,morphology and properties of the polymer.The results show that the ionic ratio can regulate the microstructure and electrophilic/nucleophilic ability of the active sites,and develop the delocalization of the anion,thus it has a good catalytic performance.In the coupling reaction of propylene oxide with CO₂ or methanol,the ionic ratio has a unique ion switch effect,which can effectively promote or inhibit the reaction.A series of Co-based poly（ionic liquid）s（Co-PILs）catalysts were prepared.The coupling of metal and poly（ionic liquid）s can be applied for selective oxidation of cyclohexane.By regulating the coordination environment between cobalt ions and poly（ionic liquid）s,the generation of free radicals can be effectively promoted,and the acidity,molecular oxygen activation and reactive oxygen desorption ability of Co-PILs are improved,thus controlling the activity and selectivity of cyclohexane oxidation reaction.Poly（ionic liquid）s（HPILs）with hollow structure were synthesized,which could be used as nanoreactors to store and enhance the catalytic activity of catalysts.In the selective oxidation of cyclohexane,HPILs can enhance the mass transfer of reactants in the nanoreactor,which greatly reduce the activation energy of the reaction,so as to effectively improve the activity and selectivity of Co Cl₂ catalysts.The HPILs realize the recovery and use of catalyst.The theoretical model of hollow spherical catalyst established confirmed the mechanism of HPILs enhancing the conversion of cyclohexane and selective production of adipic acid.