Reviewed by Lexie CornerMay 20 2025
A new study published in Eco-Environment & Health by researchers at Zhejiang University introduces a metal-free catalytic method for upcycling PET waste.
Researchers have developed a new metal-free catalytic process for converting polyethylene terephthalate (PET) waste into valuable chemical products. Using ionic liquids (ILs), the method achieves a 99 % yield of dimethyl terephthalate (DMT) and a 91 % yield of ethylene carbonate (EC) in just 2.5 hours under mild conditions. The technique relies on hydrogen bonding to activate the reactants, enabling complete PET depolymerization.
This technology provides a sustainable, efficient alternative to standard recycling procedures. It offers considerable environmental and economic benefits and the potential for large-scale industrial applications.
This diagram illustrates the process of upcycling waste plastics, including various polyesters (PET, PEF, PEA, PES, PLA) and polycarbonates (PC, PPC), using ionic liquid catalysts. The method involves the formation of hydrogen bonds between the ionic liquid and reactants, facilitating the transformation of PET into valuable chemicals such as dimethyl terephthalate (DMT) and ethylene carbonate (EC). The process efficiently depolymerizes PET and other plastics, offering a sustainable approach to plastic recycling and contributing to a circular economy. Image Credit: Eco-Environment & Health
The global plastic waste dilemma, exacerbated by the widespread use of PET, has prompted the search for more effective recycling methods. Traditional mechanical recycling technologies are often inefficient and degrade material quality over time.
Chemical recycling via methanolysis has shown promise, but issues such as incomplete depolymerization and reliance on metal-based catalysts have limited its potential. Ionic liquid-based catalysis has emerged as a promising alternative, offering a metal-free and efficient approach to recycling PET.
However, achieving total depolymerization remains a challenge. Given these limitations, further research into advanced catalytic systems is required to fully realize the potential of PET upcycling.
This innovative technology enables the complete conversion of PET into valuable chemicals such as DMT and EC in just 2.5 hours. It addresses key environmental and economic challenges and represents a significant advancement in sustainable recycling methods.
The study describes a new metal-free catalytic method for upcycling PET waste into high-value chemicals, including DMT and EC. The success of this approach lies in the use of ionic liquids (ILs), specifically [EMIm][OAc], which enable complete PET depolymerization.
Under mild conditions, the method achieves impressive yields—99 % for DMT and 91 % for EC. The formation of hydrogen bonds between the ionic liquid and the reactants is essential for activating PET’s carbonyl groups, as well as the hydroxyl groups of methanol and ethylene glycol.
These interactions enhance the reaction’s efficiency, resulting in the full conversion of PET into valuable products. What distinguishes this approach is its versatility; it can be applied to a variety of polyesters and polycarbonates, extending its utility beyond PET.
Unlike conventional recycling methods, which often rely on metal catalysts, this technique avoids the risk of metal contamination and offers a cleaner, more sustainable solution. Its ability to deliver high yields while reducing energy consumption and eliminating metal residues makes it a promising candidate for industrial-scale plastic recycling.
Our research introduces a transformative solution to the plastic waste dilemma, particularly for PET, one of the most challenging plastics to recycle. By employing a metal-free ionic liquid catalyst, we not only improve the efficiency of PET upcycling but also create a sustainable pathway for managing plastic waste. This method holds immense potential for revolutionizing recycling technologies, contributing to a circular economy by turning plastic waste into valuable raw materials that can be reused in manufacturing.
Dr. Qingqing Mei, Study Lead Researcher, Zhejiang University
This finding has important implications for the recycling industry. The novel metal-free technology for upcycling PET into high-value compounds such as DMT and EC represents a major step forward in sustainable recycling methods. By offering a cleaner and more efficient alternative to existing processes, it has the potential to significantly reduce the environmental impact of PET waste, a major contributor to global pollution.
In addition, the method’s applicability to a range of polyesters and polycarbonates expands its potential use, positioning it as a key development for industrial-scale recycling. This breakthrough supports progress toward a more circular economy, where plastic waste is continuously converted into valuable materials.
Journal Reference:
Zhang, M., et al. (2025) Targeted conversion of waste PET into dimethyl terephthalate and ethylene carbonate under metal-free conditions. Eco-Environment & Health. doi.org/10.1016/j.eehl.2025.100139.