Chemical Recycling of Bio-based Poly(3-hydroxybutyrate) Wastes Under Methanolysis Condition Catalyzed by Fe-Containing Magnetic Ionic Liquid

Abstract

An efficient method for chemical recycling of bio-based polymers Poly(3-hydroxybutyrate) (PHB) wastes was established from the perspective of biorefinery. This methanolysis reaction archived successfully transformation PHB into corresponding monomer catalyzed by imidazolium-based Fe-containing ionic liquid, 1-butyl-3-methylimidazolium tetrachloroferrate ([Bmim]FeCl4). Compared with FeCl3 or ionic liquid [Bmim]Cl, this ionic liquid showed excellent catalytic performance. The obtained product methyl 3-hydroxybutyrate (M3HB) with high purity, as a chemical raw material, can be used in various fields. Investigation also indicated that the thermal stability of catalyst played an important role in this reaction, this ionic liquid could be reused for six times without apparent decrease in the conversion of PHB or yield of M3HB. Furthermore, the effects of experimental factors, such as temperature, time, catalyst dosage and methanol dosage on the methanolysis results of PHB were examined. Kinetic study indicated that this reaction was first-order kinetic reaction with activation energy of 27.44\xa0kJ/mol. Additionally, a possible mechanism of PHB methanolysis was proposed.