武汉大学戚孝天团队报道了在可见光下通过选择性酸催化好氧氧化将聚苯乙烯化学回收为有价值的化学品。相关研究发表在2022年3月30日出版的国际知名学术期刊《美国化学会杂志》。

化学回收是最有希望的技术之一，通过提供塑料废物解决方案，有助于实现循环经济目标；然而，它仍处于早期发展阶段。

该文中，研究人员描述了第一个光驱动、酸催化的方案，用于在1bar氧气下将聚苯乙烯废物化学回收为有价值的化学品。该方案不需要光敏剂，反应条件温和，操作简单，并已在流动系统中得到验证。电子顺磁共振（EPR）研究和密度泛函理论（DFT）计算表明，单线态氧作为活性氧物种参与了该降解过程，它从三级C–H键中提取一个氢原子，通过自由基过程导致氢过氧化和随后的C–C键断裂。

值得注意的是，研究表明，聚苯乙烯和酸性催化剂的加合物可能在原位形成，它可以作为光敏剂启动单线态氧的形成。此外，氧化聚苯乙烯聚合物可能在光照下产生单线态氧中发挥作用。

附：英文原文

Title: Chemical Recycling of Polystyrene to Valuable Chemicals via Selective Acid-Catalyzed Aerobic Oxidation under Visible Light

Author: Zhiliang Huang, Muralidharan Shanmugam, Zhao Liu, Adam Brookfield, Elliot L. Bennett, Renpeng Guan, David E. Vega Herrera, Jose A. Lopez-Sanchez, Anna G. Slater, Eric J. L. McInnes, Xiaotian Qi, Jianliang Xiao

Issue&Volume: March 30, 2022

Abstract: Chemical recycling is one of the most promising technologies that could contribute to circular economy targets by providing solutions to plastic waste; however, it is still at an early stage of development. In this work, we describe the first light-driven, acid-catalyzed protocol for chemical recycling of polystyrene waste to valuable chemicals under 1 bar of O2. Requiring no photosensitizers and only mild reaction conditions, the protocol is operationally simple and has also been demonstrated in a flow system. Electron paramagnetic resonance (EPR) investigations and density functional theory (DFT) calculations indicate that singlet oxygen is involved as the reactive oxygen species in this degradation process, which abstracts a hydrogen atom from a tertiary C–H bond, leading to hydroperoxidation and subsequent C–C bond cracking events via a radical process. Notably, our study indicates that an adduct of polystyrene and an acid catalyst might be formed in situ, which could act as a photosensitizer to initiate the formation of singlet oxygen. In addition, the oxidized polystyrene polymer may play a role in the production of singlet oxygen under light.

DOI: 10.1021/jacs.2c01410

Source: https://pubs.acs.org/doi/10.1021/jacs.2c01410