Polyethylene terephthalate (PET) is a non-degradable single-use plastic and a major component 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. Particularly, hetero-geneous catalysts assisted depolymerization of post-consumer PET to monomers and other value-added chemicals is the most industrially compatible method. This review includes current progresses on the heterogeneously 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 structure-activity correlations are briefly outlined in each section. An outlook for future development is also presented.
Plastic waste poses a serious threat to the environment and it has been increasing at an alarming rate. In 2022, global plastic waste generation was reported to be around 380 million tonnes as compared to 353 million tonnes in 2019. Production of liquid fuel from plastic waste is regarded as a viable method for disposing of the plastic and utilizing its energy. Currently, a wide range of technologies have been explored for turning plastic waste into fuel, including the conventional pyrolysis, incineration, gasification and advanced oxidation. However, a systematic summary and comparative analysis of various technologies has still not reported. Traditional non-biodegradable plastic waste (NPW) treatment methods include landfilling and incineration, but these methods encounter bottlenecks and are unable to adequately address NPW issues. This review attempts to present a thorough summary of treatment methods for plastic waste (both conventional and novel treatment technologies that have recently been reported), examine their mechanism and their current state of development. Furthermore, the superiority and drawbacks of each technology are analysed and the prospects of technology application are proposed. By tackling the problems of white pollution and energy scarcity, this review intends to inspire the use of solid waste as a source of energy.
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