氯化铁催化醇解反应回收聚乳酸

Recovery of Poly(lactic acid)Through Ferric Chloride⁃catalyzed Alcoholysis

研究了三氯化铁(FeCl3)催化聚乳酸(PLA)醇解反应的机理及其影响因素。重点考察了反应温度、反应时间、催化剂用量、乙醇溶液用量对醇解反应的影响。采用傅里叶变换红外光谱仪(FTIR)、核磁共振仪(1H-NMR)、高效液相色谱仪(GPC)等方法对回收产物的结构进行了表征,并对PLA醇解反应的降解动力学进行了探究。结果表明,PLA乙醇醇解反应的最佳工艺条件为反应温度为130℃、反应时间为24 h、m(C2H5OH)∶m(PLA)=3∶1、m(FeCl3)∶m(PLA)=3∶40。在上述最佳条件下,PLA醇解反应解聚率达到99.81%,乳酸乙酯收率达到73.60%,PLA在FeCl3的催化下可完全解聚为乳酸乙酯,该反应为一级反应,反应活化能为10.28 kJ/mol。

This paper reported an investigation on the reaction mechanism and influence factors of the alcoholysis of poly(lactic acid)(PLA)catalyzed with ferric chloride(FeCl3).The effects of reaction temperature,reaction time,and addition amounts of catalyst and ethanol solution on the alcoholysis reaction were investigated in detail.The chemical structure of the alcoholysis product was characterized with 1H-NMR,FTIR,and GPC.Furthermore,the degradation kinetics of the alcoholysis reaction was also explored.The results showed that the optimum process conditions were determined as a reaction temperature of 130℃,a reaction time of 24 h,a C2H5OH/PLA mass ratio of 3/1 and a FeCl3/PLA mass ratio of 3/40.Under the above optimum conditions,the alcoholysis reaction led to a depolymerization rate of 99.81%and an ethyl lactate yield of 73.60 wt%for PLA.It was found that PLA could be completely depolymerized into ethyl lactate under the catalysis of FeCl3,acting as a first-order reaction with a reaction activation energy of 10.28 kJ/mol.