Depolymerization of plastics by means of electrified spatiotemporal heating

Qi Dong, Aditya Dilip Lele, Xinpeng Zhao, Shuke Li, Sichao Cheng, Yueqing Wang, Mingjin Cui, Miao Guo, Alexandra H. Brozena, Ying Lin, Tangyuan Li, Lin Xu, Aileen Qi, Ioannis G. Kevrekidis, Jianguo Mei, Xuejun Pan, Dongxia Liu, Yiguang Ju, Liangbing Hu

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

Depolymerization is a promising strategy for recycling waste plastic into constituent monomers for subsequent repolymerization1. However, many commodity plastics cannot be selectively depolymerized using conventional thermochemical approaches, as it is difficult to control the reaction progress and pathway. Although catalysts can improve the selectivity, they are susceptible to performance degradation2. Here we present a catalyst-free, far-from-equilibrium thermochemical depolymerization method that can generate monomers from commodity plastics (polypropylene (PP) and poly(ethylene terephthalate) (PET)) by means of pyrolysis. This selective depolymerization process is realized by two features: (1) a spatial temperature gradient and (2) a temporal heating profile. The spatial temperature gradient is achieved using a bilayer structure of porous carbon felt, in which the top electrically heated layer generates and conducts heat down to the underlying reactor layer and plastic. The resulting temperature gradient promotes continuous melting, wicking, vaporization and reaction of the plastic as it encounters the increasing temperature traversing the bilayer, enabling a high degree of depolymerization. Meanwhile, pulsing the electrical current through the top heater layer generates a temporal heating profile that features periodic high peak temperatures (for example, about 600 °C) to enable depolymerization, yet the transient heating duration (for example, 0.11 s) can suppress unwanted side reactions. Using this approach, we depolymerized PP and PET to their monomers with yields of about 36% and about 43%, respectively. Overall, this electrified spatiotemporal heating (STH) approach potentially offers a solution to the global plastic waste problem.

Original languageEnglish (US)
Pages (from-to)488-494
Number of pages7
JournalNature
Volume616
Issue number7957
DOIs
StatePublished - Apr 20 2023

All Science Journal Classification (ASJC) codes

  • General

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