Chemical recycling processes of waste polyethylene terephthalate using solid catalysts

Polyethylene terephthalate (PET) is a non-degradable single-use plastic. It is one of the major components of plastic waste in landfills. Chemical recycling is one of the most widely adopted methods to transform post-consumer PET into PET’s building block chemicals. Non-catalytic depolymerization of PET is very slow and requires high temperatures and/or pressures. Recent advancements in the field of material science and catalysis have delivered several innovative strategies to promote PET depolymerization under mild reaction conditions. Heterogeneous catalysts assisted depolymerization of post-consumer PET to monomers and other value-added chemicals is the most industrially compatible method. This review provides current progresses on the heterogeneous catalyzed chemical recycling of PET. It describes four key pathways for PET depolymerization including, glycolysis, pyrolysis, alcoholysis, and reductive depolymerization. The catalyst function, active sites, and the structure-activity are briefly outlined in each section. An outlook for future development is presented.