美国马里兰大学Hu, Liangbing研究团队报道了用带电时空加热的方法对塑料进行解聚。相关研究成果发表在2023年4月19日出版的国际知名学术期刊《自然》。

解聚是一种很有前途的策略，可以将废塑料回收为成分单体，用于随后的再聚合。然而，许多商品塑料不能使用传统的热化学方法选择性解聚，因为很难控制反应过程和途径。尽管催化剂可以提高选择性，但它们容易受到性能退化的影响。

该文中，研究人员提出了一种无催化剂、远未平衡的热化学解聚方法，该方法可以从商品塑料（聚丙烯（PP）和聚对苯二甲酸乙二醇酯（PET））中通过热解产生单体。这种选择性解聚过程由两个特征实现：（1）空间温度梯度和（2）时间加热分布。空间温度梯度是使用多孔碳毡的双层结构实现的，其中顶部电加热层产生热量并将热量向下传导到下面的反应器层和塑料。当塑料遇到穿过双层的不断升高的温度时，由此产生的温度梯度促进塑料的连续熔化、芯吸、蒸发和反应，从而实现高度解聚。

同时，通过顶部加热器层的脉冲电流产生一个时间加热曲线，其特征是周期性的高峰值温度（例如，约600°C），以实现解聚，但瞬态加热持续时间（例如，0.11s）可以抑制不必要的副反应。使用这种方法，研究人员将PP和PET解聚为它们的单体，产率分别为约36%和约43%。总的来说，这种带电时空加热（STH）方法有可能为全球塑料垃圾问题提供解决方案。

附：英文原文

Title: Depolymerization of plastics by means of electrified spatiotemporal heating

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

Issue&Volume: 2023-04-19

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, 0.11s) 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.

DOI: 10.1038/s41586-023-05845-8

Source: https://www.nature.com/articles/s41586-023-05845-8