Preparation And Catalytic Performance Of Acid Functional Poly(Ionic Liquid)s

Poly(ionic liquid)s have dual characters of polymers and ionic liquids.It improves the thermal stability and mechanical stability of the ionic liquid under the premise of conductivity,functional designability and good catalytic performance.At the same time,Poly(ionic liquid)s catalyst is convenient to separate and reuse after the end of the reaction.So it is eco-friendly.In this paper,three acid-functionalized poly(ionic liquid)s catalysts were synthesized by(1)grafting ionic liquid on polymer;(2)monomer ionic liquid free radical polymerization self-assembly.The structure and thermal stability of the synthesized catalyst were characterized by NMR,FTIR,TG-DTA,SEM,TEM and N2 adsorption/desorption isotherms test.The catalytic effects of ionic liquid polymer catalysts synthesized under different experimental conditions were investigated,and the effects of experimental factors such as catalytic time,temperature and catalyst dosage on the catalytic performance were discussed.The main research work was as follows:The imidazole was grafted with polyethylene glycol(PEG)of different molecular weights(400,600,1000,2000),and then reacted with 1,3-propane sultone.The temperature-controlled sulfuric poly(ionic liquid)s DAILx(x=400,600,1000 or 2000)was obtianed by the sulfonation of concentrated sulfuric acid.Due to the introduction of the PEG chain,the reaction can achieve the effect of 'homogeneous reaction at high temperature,two phase separation at low temperature'.The separation effect of different molecular weight catalysts in different solvents was finally determined:A Beckmann rearrangement reaction of cyclohexanone oxime was carried out by using 2 ml toluene as solvent and a PEG chain having a molecular weight of 1000 as a catalyst.The experimental results show that the temperature-controlled poly(ionic liquid)reaches the conversion of 83.7%and the selectivity of 73.8%at 90? for 2 h.The DAIL was reused 5 times,and the catalytic performance did not decrease significantly1-vinyl-3-propane sulfonic acid imidazolium salt was obtained by 1-vinylimidazole and 1,3-propane sultone,and then reacting with concentrated sulfuric acid to obtain monomeric ionic liquid.PBPIL was synthesized by the addition of AIBN for free radical polymerization,the introduction of P123 followed by Soxhlet extraction.The specific surface area and pore volume of the final product could be controlled by the prepolymerization time.The resulting catalyst have a specific surface area of 8 to 140 m2/g and a pore volume of 0.01 to 0.66 cm3/g.It was used to catalyze the liquid phase Beckmann rearrangement reaction of cyclohexanone oxime.The experimental results show that the conversion rate and selectivity of the porous ionic liquid polymer are higher than that of the monomeric acid functionalized ionic liquid,the polyionic liquid without P123 and the mesoporous material SBA-15-SO3H supporting the sulfonic acid,77.8%and 78.9%respectively.After 5 cycles of recycling,the catalytic effect remained almost unchanged.1-allyl-3-vinylimidazolium ionic liquid was synthesized from 1-vinylimidazole and 3-chloropropene.It was mixed with P123 in deionized water and ammonium persulfate(APS)was used to trigger free radical self-polymerization.After removing of P1 23 by soxhlet extraction,a phosphotungstic acid polyionic liquid(PIL-PW)was obtained by anion exchange method.The results showed that after anion exchange,the PIL-PW has a large specific surface area,which was used for the catalytic oxidation of benzyl alcohol,achieving a conversion of 91.4%and a selectivity of 93.2%.Moreover,PIL-PW maintains high catalytic activity after 7 runs.