Ferric chloride as an efficient and reusable catalyst for methanolysis of poly(lactic acid) waste

Abstract

Ferric chloride (FeCl3) was used to catalyze the methanolysis of poly(lactic acid) (PLA) to recover methyl lactate. The effects of experimental parameters such as reaction temperature, reaction time, amount of FeCl3 and dosage of methanol on results were studied in detail. The results showed that under the optimized reaction conditions of n(methanol):n(PLA) = 5:1, n(FeCl3):n(PLA) = 0.01:1, 130 °C and 4.0 h, the conversion of PLA reached 96.0 % and the yield of methyl lactate was up to 87.2 %. FeCl3 could be repeatedly used at least 6 times without significant decrease in the conversion of PLA and yield of methyl lactate under the given conditions. The kinetics of the reaction was also investigated. The results indicated that the methanolysis of PLA catalyzed by FeCl3 was a first-order kinetic reaction with activation energy of 32.41 kJ/mol.