Catalysed Depolymerization Of Polycarbonate And Polyethylene Terephthalate In Supercritical And Sub-Critical Water

The catalysed depolymerization of polycarbonate(PC) and Polyethylene terephthalate(PET) were studied in supercritical and sub-critical water,inspected conditions in details of reaction temperature, time,catalysts to the depolymerization rate of PC/PET as well as the yield of BPA,phenol,PTA and EG influenced.According to the distribution of catalyzed depolymerization,and unified the chain link characteristic of PC and PET,proposed the depolymerization mechanism of PC/PET.The concrete conclusions were as follows:Catalyzed depolymerization of PC in supercritical and sub-critical water was studied under the conditions of temperature(593～693 K), pressure(3.60～52.28 MPa),reaction time(5～85 min),ratio of water/PC (8.0).It was found that PC can be completed depolymerization in supercritical and sub-critical water,the yield of BPA and phenol were mainly effected by the reaction temperature,the time and the catalysts; Along with the temperature ascension and the time increased,the yield of BPA increased and then dropped,and the phenol increased gradually.In supercritical and sub-critical water,BPA under the conditions of 653 K,25 min,ratio of PC 8.0,the catalyst(NaOH,0.001 g),the best yield of BPA was 38.20%;The phenol in temperature 693 K,time 45 min,ratio of PC 8.0,the catalyst(NaOH,0.001 g) maximum output was 52.00%.Catalyzed depolymerization of PET in supercritical and sub-critical water was studied under the conditions of temperature(593～693 K), pressure(3.60～52.28 MPa),reaction time(5～85min),ratio of water/PET (8.0).In the experimental condition scope,it was found that the depolymerization product mainly were PTA,EG,DMT and so on.The yield of PTA and EG mainly effected by the temperature,the time and the catalyst.In the experimental value scope,the yield of the main products PTA and EG all increased,the PTA maximum output was:The 72.64%,EG maximum output was 22.50%,responded the condition was under the conditions of temperature 653 K,time 25 min,the ratio of water/PET was 8.0,NaOH(0.001 g).Catalyzed depolymerization of PC/PET in supercritical and sub-critical water was studied under the conditions of temperature(593-693 K), pressure(14.96～44.90 MPa),reaction time(5～85min),ratio of water and PET/PC(1:1)(8.0).It was found that along with the reaction temperature and the time increased,the depolymerization rate of PC/PET and the yield of BPA,phenol,PTA and EG were increased gradually.In supercritical and sub-critical water,the completed depolymerization of PC and PET were under the conditions of temperature 653 K,reaction time 25 min,NaOH(0.001 g).Both of PC and PET according to the empirical datum in supercritical and sub-critical water that catalyzed depolymerization to respond for the comparation,through the connection empirical datum,obtained the response activation energy was 90.32 kJ·mol^-1and 66.84 kJ·mo1^-1.The depolymerization product was analysised,and unified the chain link characteristic,proposed the catalysed depolymerization reaction mechanisms of PC and PET in supercritical and sub-critical water.