[Searching for LAB] Plastic Recycling Now Cheaper Than New Raw Materials

Joint Research Team from Ewha Womans University and Sogang University
Develops Recoverable "Bead Catalyst"
Improved Yields: Over 99% PET Decomposition

A new technology has been developed that allows for easy recovery of catalysts in the process of chemically decomposing waste plastics and converting them back into raw materials for new plastics. The key innovation is forming the catalyst into small solid beads, which can be filtered out after the reaction. By reducing purification processes, this approach is expected to lower both recycling costs and greenhouse gas emissions.

Researchers Yongsoo Kim, a researcher in the Department of Chemical and Biological Engineering at Sogang University (from left), Jonggeol Na, a professor in the Department of Chemical and Biomolecular Engineering at Ewha Womans University, Youngwon Lee, a researcher in the Department of Chemical and Biomolecular Engineering at Ewha Womans University, and Hyeongjun Kim, a professor in the Department of Chemical and Biological Engineering at Sogang University, who developed a solid bead catalyst technology that decomposes waste plastics and returns them to recyclable raw materials, are posing for a commemorative photo. Ewha Womans University

On August 14, a research team led by Professor Jong-Gul Na from the Department of Chemical and Biomolecular Engineering at Ewha Womans University and Professor Hyungjun Kim from the Department of Chemical and Biomolecular Engineering at Sogang University announced the development of a reusable solid bead catalyst. The results of this research were published last month in the international journal Nature Communications.

The research team focused on PET (polyethylene terephthalate), which is used in beverage bottles, packaging containers, and polyester fibers. PET accounts for about 10 to 15% of plastic waste.

Chemical recycling of PET requires breaking it down into bis(2-hydroxyethyl) terephthalate (BHET), a raw material for plastics. Previously, metal catalysts dissolved in the reactant were mixed with the product, making it necessary to conduct several rounds of purification to remove the catalyst. This process added extra cost and energy consumption.

The research team designed the catalyst as solid beads with interconnected pores, allowing the reactants to permeate into the beads. As a result, the team was able to decompose over 99% of PET, achieving a maximum BHET yield of 96.9%. After the reaction, the catalyst could be easily recovered through filtration. Even after 30 cycles of reuse, the catalyst maintained an average BHET yield of 90.7%.

With easy catalyst recovery, the purification process was simplified. Instead of repetitive recrystallization, a two-step evaporation process was applied, markedly reducing the amount of steam required. According to the team's analysis, the minimum selling price of regenerated BHET was $1.02 per kilogram, lower than the market price of $1.35 per kilogram for new raw materials produced from petroleum. The greenhouse gas emissions were also analyzed to be 1.90 kilograms of carbon dioxide per kilogram of recycled PET, about one-third the emissions generated from producing and incinerating new PET.

Professor Na stated, "This research is significant not only because the catalyst itself was well designed, but also because we applied it to an actual process and verified both economic and environmental feasibility. We expect this to become a practical technology that accelerates the circular economy for waste plastics."

This content was produced with the assistance of AI translation services.