HomeIndustry InsightsPET Waste Converted into Higher-Value Chemicals Without External Hydrogen, Study Finds

PET Waste Converted into Higher-Value Chemicals Without External Hydrogen, Study Finds

2026-05-29

Researchers from Peking University have reported a new catalytic method for converting post-consumer PET plastics into higher-value chemical products without the need for an external hydrogen supply. The study was published in the journal Engineering.

The process transforms waste polyethylene terephthalate (PET) together with methanol into lactic acid (LA) and 1,4-cyclohexanedicarboxylic acid (CHDA) under relatively mild reaction conditions. According to the researchers, the approach uses a commercially available Ru/C catalyst throughout the entire reaction sequence, simplifying the conversion process.

In the first stage, PET is depolymerized in a sodium hydroxide–methanol system at 160 °C. During this step, ethylene glycol derived from PET reacts with methanol to generate lactic acid and hydrogen. Additional hydrogen is also produced through methanol dehydrogenation. The hydrogen generated in situ is subsequently utilized for the hydrogenation of terephthalic acid (TPA), converting it into CHDA without relying on external hydrogen cylinders.

The authors noted that this integrated hydrogen utilization strategy improves atom economy and enables simultaneous valorization of both major PET-derived components. Under optimized conditions, lactic acid was obtained with a reported yield of 55% and purity above 88%, while CHDA achieved a yield of 84% with purity exceeding 99%.

The study also included isotopic labeling experiments to investigate the reaction pathway. Results suggested that ethylene glycol plays a major role in hydrogen generation and lactic acid formation, while also helping suppress undesired side reactions associated with methanol conversion.

Researchers further tested the process using various real-world PET waste materials, including beverage bottles, food packaging containers, fibers, and colored PET products. The results demonstrated compatibility with multiple post-consumer PET feedstocks.

Although catalyst activity gradually declined after repeated recycling cycles due to nanoparticle agglomeration and partial metal leaching, the work highlights a potential pathway for more integrated and value-added chemical recycling of PET plastics.

The paper, titled “Upcycling PET Plastics with Methanol into Lactic Acid and 1,4-Cyclohexanedicarboxylic Acid,” was authored by Zhenbo Guo, Haoyu Chen, Shuheng Tian, Meiqi Zhang, Meng Wang, and Ding Ma.

Source: Higher Education Press / Engineering Journal

DOI: 10.1016/j.eng.2026.02.015