TY - JOUR
T1 - Chemical Recycling of Polystyrene to Valuable Chemicals via Selective Acid-Catalyzed Aerobic Oxidation under Visible Light
AU - Huang, Zhiliang
AU - Shanmugam, Muralidharan
AU - Liu, Zhao
AU - Brookfield, Adam
AU - Bennett, Elliot L.
AU - Guan, Renpeng
AU - Vega Herrera, David E.
AU - Lopez-Sanchez, Jose A.
AU - Slater, Anna G.
N1 - Funding Information:
The authors are grateful to the EPSRC (EP/R009694/1 and EP/R511729/1) for funding, including the EPR National Facility at Manchester (EP/V035231/1 and EP/S033181/1), the China Scholarship Council and the University of Liverpool for a PhD studentship (RPG), the Royal Society for a University Research Fellowship (AGS), the Analytical Services of the Department of Chemistry of the University of Liverpool for product analysis, and Vapourtec Ltd. for the free loan of E-series flow chemistry equipment. They also thank Dr. Steven Robinson (Technical Support Officer in the Materials Innovation Factory, University of Liverpool) and Mr. Henry Morris (Department of Chemistry, University of Liverpool) for technical assistance and Mark Norman and his team in the EEE Department Electronics Workshop and Mr. Gordon Bostock and Chemistry Electronics Workshop for help with the design and fabrication of our photoreactors. This work made use of equipment from the Analytical Services/Department of Chemistry at the University of Liverpool as well as the shared equipment at the Materials Innovation Factory (MIF) created as part of the U.K. Research Partnership Innovation Fund (Research England) and cofounded by the Sir Henry Royce Institute. The theoretical calculations were performed on the supercomputing system in the Supercomputing Center of Wuhan University.
Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.
PY - 2022/4/13
Y1 - 2022/4/13
N2 - 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.
AB - 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.
KW - Catalysis
KW - Light
KW - Oxidation-Reduction
KW - Photosensitizing Agents/chemistry
KW - Polystyrenes
KW - Singlet Oxygen/chemistry
U2 - 10.1021/jacs.2c01410
DO - 10.1021/jacs.2c01410
M3 - Article
C2 - 35353526
VL - 144
SP - 6532
EP - 6542
JO - American Chemical Society. Journal
JF - American Chemical Society. Journal
SN - 0002-7863
IS - 14
M1 - 144
ER -