Catalytic conversion of polyoxymethylene with bio-derived substrates: kinetic modeling on solvent enhancement effect and experimental studies on reaction mechanism

Catalytic conversion of waste polyoxymethylene plastics to renewable and value-added chemicals represents a promising area in green chemistry. Previous studies in both academia and industry have focused on thermal depolymerization under harsh operating temperature and pressure. In this work, we have investigated the detailed reaction mechanism for cascade depolymerization and etherification of polyoxymethylene with bio-derived polyols into valuable oxygenates. As one of the highlights in this work, we proposed and validated a two-step mechanism involving depolymerization and nucleophilic attack C O C bond. Kinetic modeling, IR and NMR spectra revealed mechanistic information for solvent-enhancement: the synergism of cation (Bi 3+ ), anion (OTf - ) and 1,4-dioxane (1) induces formation of intermolecular H bonding thus activating C O H bond in polyol molecules, and (2) facilitates nucleophilic attack on carbocation in polyoxymethylene. The outcome of this work will provide useful fundamental data for rational design of industrial processes involving atomic efficient conversion of various polymers into value-added products.