In recent years, microwave catalysis technology achieves rapid and uniform energy transfer via the dielectric heating effect, which can markedly shorten reaction duration and reduce energy consumption. It can also precisely tune product distribution, demonstrating unique advantages and broad application prospects in the thermochemical conversion of waste plastics. A team of researchers led by Junwang Tang from Tsinghua University in Beijing, China, recently published a critical review in Carbon Future on the microwave-driven conversion of waste plastics into high-value chemicals.
The team published their review in Carbon Future on July 29, 2026.
This review summarizes recent progress in microwave catalytic conversion of waste plastics. It covers three types of plastics: polyesters, polyolefins, and others (such as PS and mixed waste). For polyester plastics (PET and PLA), the review reports that PET can be efficiently depolymerized by microwave-assisted glycolysis. A ZnO catalyst gives a BHET yield of over 95% at 210 °C within 45 minutes. And, Mn3O4/ZnO composite catalyst achieves complete PET conversion at 175 °C in just 5 minutes, with a BTEX selectivity of 88%. Titanate nanotube catalysts reduce reaction time by two-thirds compared with conventional heating. In terms of PLA conversion, microwave catalytic treatment can achieve a monomer yield of approximately 90 % within 10 min at a relatively mild temperature of 240 °C. Similarly, alkaline hydrolysis enables efficient PLA degradation, with a degradation efficiency exceeding 90 % under the condition of 100 °C and 10 min reaction time.
A variety of high-efficiency catalysts have been developed for the microwave catalytic conversion of polyolefins including LDPE, HDPE, and PP, delivering distinctive product selectivity and catalytic performance. Specifically, Ti3AlC2 MAX catalyst enables the one-step conversion of polyolefins into high-purity hydrogen with a volume fraction higher than 75% and graphitic carbon nanofibers. Benefiting from the synergistic bimetallic effect, Pt-promoted Fe/Ni bimetallic catalyst can realize a hydrogen yield of 53.9 mmol/g with a selectivity up to 90%. In addition, Zn/b-ZnO catalyst exhibits excellent adaptability to complex substrates, achieving nearly 100% conversion of mixed landfill plastics to high-value lubricant precursors without the assistance of external hydrogen. Moreover, HZSM-5 zeolite can effectively reduce the reaction activation energy to 20.3 kJ/mol, while Ru-based bifunctional catalysts and Pt/WO3/ZrO2-HY catalytic systems also possess remarkable performance for the production of high-quality liquid fuels from polyolefin waste.
In addition to polyolefins, microwave catalytic systems also present prominent advantages in the valorization of other types of waste plastics. For PS degradation, the Zn/b-ZnO catalytic system can realize nearly 100% PS conversion at 270 °C and obtain a styrene monomer yield of 0.8 g, whose energy consumption is merely 63% that of traditional thermal catalysis. For difficult-to-treat mixed plastic waste containing PVC and PTFE, FeNi/Ni/C catalyst can efficiently convert such complex substrates into hydrogen and carbon nanotubes (CNTs), achieving an excellent H2 yield of over 922 mmol/g and a CNT yield higher than 10600 mg/g.
For future prospects, the review suggests several research directions. These include clarifying multi-scale reaction mechanisms, developing stable catalysts with high resistance to coking and sintering, designing continuous-flow microwave reactors, conducting life-cycle and techno-economic assessments, and using artificial intelligence to assist catalyst screening. These efforts aim to push microwave catalytic plastic conversion toward industrial application.
About the Authors：
Jibo Qin is a postdoctoral researcher in the Department of Chemical Engineering, Tsinghua University. His research primarily centers on the chemical recycling and high-value upcycling of waste plastics. His ongoing work mainly covers microwave-assisted catalysis and thermal catalysis, with a particular focus on exploring catalyst structure–activity relationships and revealing the intrinsic mechanisms of plastic upcycling.
Prof. Junwang Tang is the corresponding author of this review. He is a Fellow of The Academia Europaea and the European Academy of Sciences, as well as a Senior Research Fellow of the Royal Society-Leverhulme Trust. He also holds fellowship titles from the Royal Society of Chemistry and the Institute of Materials, Minerals and Mining, and serves as an Honorary Fellow of the Chinese Chemical Society. Previously, Prof. Tang served as the Director of the University College London (UCL) Materials Center and held the Chair Professorship in Materials Chemistry and Materials Engineering at UCL. He is recognized as a national high-level talent in China and a Yangtze River Chair Professor, and has also acted as Vice Chairman of the Society of Chinese Professors in the UK. Currently, he holds the inaugural Chair Professorship of Carbon Neutrality at Tsinghua University and serves as the Director of the Industrial Catalysis Center in the Department of Chemical Engineering. He additionally maintains a visiting professorship at UCL and acts as one of fifteen overseas council members of the Western Returned Scholars Association. Prof. Tang's pioneering research focuses on the integration of photocatalysis and thermal catalysis. His work enables the activation of small molecules including H2O, N2, CH4, and CO2, facilitating the conversion and storage of renewable energy in the forms of green hydrogen, ammonia, and methanol. His research interests also extend to microwave catalysis for waste plastic recycling. Furthermore, he employs time-resolved spectroscopy to elucidate the fundamental mechanisms of photothermal catalysis. Prof. Tang currently works as an editor or associate editor for five international journals, including Applied Catalysis B, Chinese Journal of Catalysis, and EES Solar, and has been honored with more than ten international academic awards throughout his career.
DOI Link:
https://doi.org/10.26599/CF.2026.9200082
About Carbon Future
Carbon Future (https://www.sciopen.com/journal/2960-0561) is an open access, peer-reviewed, and international interdisciplinary journal sponsored by Tsinghua University and published by Tsinghua University Press. It serves as a platform for researchers, scientists, and industry professionals to share their findings and insights on carbon-related materials and processes, including catalysis, energy storage and conversion, as well as low carbon emission process and engineering. It features cutting-edge research articles, insightful reviews, perspectives, highlights, and news and views in the field of carbon. The article publishing charge is covered by the Tsinghua University Press. Carbon Future has been indexed by Scopus, Ei compendex, DOAJ, Inspec, CAS…, and it aims at being a leading journal in related fields.
