Novel catalytic method transforms plastic waste into high-value chemicals

The widespread use of plastic has resulted in one of the most pressing waste management challenges of the modern era. With cumulative waste reaching an estimated 6,300 million tons, finding solutions that are both environmentally responsible and cost-effective has become an urgent priority. Recycling is often viewed as the ideal solution, but traditional methods have significant drawbacks. Many rely on extreme temperatures or expensive noble-metal catalysts, producing complex mixtures that are difficult to separate. Others break down plastics only partially or are energy intensive which negates the environmental benefits.

To this end, a research group including Dr. Yafei Fan from Shandong University, China and Dr. Fawei Lin from Tianjin University, China, published an article in Research on June 10, 2025, sharing insights on a study by Conk et al. featured in Science, which presents a catalytic approach for converting polyethylene and polypropylene and their mixtures, commonly used in packaging and consumer goods, into reusable chemicals. This catalytic method uses inexpensive, widely available base-metal catalysts, operates under relatively mild conditions, and produces fewer unwanted byproducts.

“The developed method has the potential for efficient conversion of plastic waste without requiring extensive pretreatment or separation processes,” Dr. Fan notes.

The process uses two catalysts: tungsten oxide on silica (WO₃/SiO₂) and sodium-doped gamma-alumina (Na/ɣ-Al₂O₃). Working in tandem, they drive a reaction known as catalytic cracking and isomerizing ethenolysis, breaking down long polymer chains into light olefins (compounds made up of hydrogen and carbon, with one or more pairs of carbon atoms linked by a double bond) such as propylene and isobutylene. These olefins are highly valued as feedstocks for fuels and polymers, with a combined global market value exceeding 40 billion US dollars.

Each catalyst plays a distinct role in the process: WO₃/SiO₂ facilitates metathesis, breaking down long polyolefin chains by cleaving and rearranging their double bonds, while Na/ɣ-Al₂O₃ promotes isomerization by shifting the positions of those double bonds. Working together, these catalysts enable a highly efficient transformation at just 320 °Celsius (C) under 15 bar of ethylene for 90 minutes—significantly milder conditions compared to the 500 °C or higher temperatures typically required for pyrolysis. In experimental trials, this method converted over 95% of the carbon in plastic into useful products, achieving a propylene yield as high as 87% for polyethylene.

The researchers also identified potential areas for improvement that could make the method more viable for plastic recycling. One major limitation is the declining stability of the catalysts over multiple cycles, particularly due to sintering and carbon deposition. To mitigate these effects, they proposed structural modifications such as doped architectures, core–shell designs, and regeneration strategies to enhance durability. Additionally, integrating this catalytic process with advanced sorting systems, such as AI-powered near-infrared detection, could improve the overall recycling efficiency. They also stressed the need to evaluate the method on mixed plastic waste streams, a significant challenge in recycling.

Despite these challenges, the catalytic strategy proposed by Conk et al. represents a promising step toward scalable and sustainable plastic recycling. This Perspective article highlights how insights from the study by Conk et al. could help design next-generation catalysts that are more robust, selective, and capable of handling a wider variety of plastic materials.

“Base-metal catalysts have shown promise for high-yield conversion. Continued research into advanced catalysts, such as high-activity single-atom catalysts, and optimized upcycling processes could reveal new, highly efficient plastic waste disposal methods,” Dr. Lin concludes.

 About Shandong University

Shandong University is a is a key comprehensive university with a long and honorable history, broad variety of disciplines, strong academic strength and distinctive characteristics. Spread across an area of over 533 hectares, the university has campuses in three cities and currently offers 12 general disciplines for undergraduates and postgraduates. The university boasts 12 State-level scientific research platforms, as well as six projects in the national program for introducing talent for discipline innovation in colleges and universities. With an already profound academic foundation and even more untapped potential, SDU is widely tipped to achieve its goal of becoming one of the world's highest-ranking universities.

Website: https://www.en.sdu.edu.cn/ 

About Tianjin University

Tianjin University, founded in 1895 as Peiyang University, is the oldest modern higher education institution in China. With a history spanning over 130 years, it has played a pioneering role in Chinese education and innovation—from developing the country's first aero engine to establishing its first hydraulics laboratory. Today, Tianjin University is a leading research and teaching institution, home to over 40,000 students, including undergraduates, master's, and doctoral candidates. Its enduring legacy reflects the spirit of resilience and progress, making it a key contributor to China’s scientific and technological advancement.

Website: http://en.tju.edu.cn 

About the Journal Research

Launched in 2018, Research is the first journal in the Science Partner Journal (SPJ) program. Research is published by the American Association for the Advancement of Science (AAAS) in association with Science and Technology Review Publishing House. Research publishes fundamental research in the life and physical sciences, as well as important findings or issues in engineering and applied science. The journal publishes original research articles, reviews, perspectives, and editorials and has an impact factor of 10.7 and a CiteScore of 13.3.

Sources: https://doi.org/10.34133/research.0731