Study On Synthesis, Characterization And Catalytic Properties Of Functionalized Heteropolyanion-based Ionic Liquids

As the increase of environmental pollution and awareness of environmental protection, green chemistry is one of important direction of modern science. Ionic liquids have been applied in organic synthesis, electrochemistry, separation purification, and materials science because of their unique physical and chemical properties. As a new catalyst, heteropolyanion-based ionic liquids (HPA-ILs) have the advantages of ionic liquids, also have the advantages of heteropolyacids. In recent years, the study of HPA-ILs has been given more attention.In this paper, HPA-ILs were obtained by combining Keggin heteropolyanions and organic cations. We studied the preparation, characterization of HPA-ILs, and its application in catalysis reactions. The main contents are as following:(1)Several functional HPA-ILs were synthesized and characterized. The functionalized HPA-ILs were synthesized by combining Keggin heteropolyanions and organic cations. The HPA-ILs were characterized by FT-IR, NMR, and TG-DSC.(2)Six kinds of HPA-ILs were used in process of direct hydration of camphene for producing isoborneol. Compared with traditional acidic catalysts, [BSmim]4SiW12O40 showed good catalytic activity. The effects of the temperature, catalyst dosage, reactant molar ratio and other factors on the reaction process were also studied in detail. The optimum reaction conditions were as following:the reaction temperature 80 ?, the amount of catalyst 20wt%(percentage of the total mass of reactants), reactant ratio of 1:1:2 (mass ratio), reaction time 3h. Under the optimal reaction conditions, camphene conversion rate was 20.67%, the selectivity for isoborneol was 87.77%. Moreover, [BSmim]4SiW12O40 could be easily recovered, and reused five times without any obvious decrease in catalytic activity.(3)Six kinds of HPA-ILs were obtained by combining Keggin heteropolyanions and organic cations, and used as catalysts for esterification reaction of diethylene glycol monobutyl ether (DGBE) with acetic acid. Compared with H2SO4, H3PW12O40, and Amberlyst-15 resin, [BSEt3N]3PW12O40 and [BSmim]3PW12O40 performed excellent catalytic activities. The effect of temperature, catalyst loading, and molar ratio of the reactants on the conversion of DGBE was studied in detail. A pseudo-homogeneous (PH) kinetic model was applied successfully to correlate the experimental data, the kinetic parameters were estimated by minimizing the sum of residual squares between calculated values of conversion of DGBE. It can be seen that the calculated conversion of DGBE by the reaction kinetic model was in good agreement with those obtained from experiments. Moreover, the two catalysts could be easily recovered and reused five times without any obvious decrease in catalytic activity.