Glycolysis Of Poly(Ethylene Terephthalate)(PET) Using Basic Ionic Liquids As Catalysts

With the penetrating of ionic liquid applied to the analysis of the separationtechnology，the research of the liquid anions and cations also progressed.Especially,with the development of the ionic liquids’ application for industry, it was imperative todevelop the related experimental method. Further more, as the novel catalysts, ionicliquid applied to degradation of PET, which consistent with the requirements ofenvironmental protection. In the future, the traditional catalyst for degradation PET willbe gradually replaced.This study will demonstrated the mechanism of the PETdegradation from the choice of ionic liquids, the method of PET degradation anddifferent alcohols as catalyst.We studied the PET alcoholysis reaction under the conditions of the several ionicliquid as a catalyst.[Bmim]OH, a alkaline ionic liquid，showed higher catalyticactivity compared to several other ionic liquid [Bmim]Ac、[Bmim]Cl and [Bmim]HCO3. Moreover, through the IR,NMR and TGA characterization methods, weconfirmed that the alcoholysis product is the polyethylene terephththalate. Theexperiment also demonstrated the different reaction parameters had a great impact on it.Eventually，we acquired the optimum reaction condition：temperature is190℃，reaction time is2hours，the ratio of PET and EG usage is1:10and the amount ofcatalyst is0.1g. Under this optimum reaction condition，the conversion of PET was100%and yield of BHET was71.2%.The combination of the alkaline ionic liquid as catalyst and microwave radiation asthe energy source, in this condition of degradation PET, the characterization of NMRand IR showed that the final product is polyethylene terephthalate. Furthermore，thecationic structure of ionic liquids，the polarity of the ionic liquid and the absorption rateof the microwave energy,which had a great influence on the effect of degradation PET.Experimental results suggested that the inducting microwave methods could increasethe degradation rate of PET and shorten the reaction time compared to the conventionaldegradation method.On the basis of prior studies，we research the PET alcoholysis reaction of waste PET polyester under these condition：microwave radiation is the energy source andSeveral polyhydric alcohol were catalysts such as1,4-butanediol, glycerol, ethyleneglycol and1,2-propylene glycol, etc. The results demonstrated that except1,2-propylene glycol, PET could gain the high alcoholysis conversion rate in three otherpolyhydric alcohols. Based on the analysis of the alcoholysis process and product, wecould get the possible mechanism.