UCLA-Ewha process turns mixed plastic waste into hydrogen while trapping carbon

Researchers co-led by UCLA Samueli and Ewha Womans University demonstrated alkaline thermal treatment that converts mixed PET, polyethylene and polypropylene waste into high-purity hydrogen while keeping most carbon out of the atmosphere, ScienceDaily reported from University of California - Los Angeles materials. In the process, sodium hydroxide reacts with plastics under heat to produce hydrogen more than 90% pure without sorting the three common polymers first. The method runs hundreds of degrees Celsius cooler than conventional steam gasification. A thermal oxidation pretreatment adds reactive groups so PE and PP break down alongside PET. During the reaction, sodium hydroxide captures carbon as solid sodium carbonate; analysis found more than 75% of the plastic carbon ended in stable carbonates or liquid organic residues, with less than 13% in the gas phase and negligible direct atmospheric release. Sodium carbonate can be converted to calcium carbonate for mineral storage. Co-corresponding authors Ah-Hyung Alissa Park of UCLA and Woo-Jae Kim of Ewha adapted a biomass hydrogen method to plastics. The findings appear in Proceedings of the National Academy of Sciences. The team said more work is needed before commercial scale and economic hydrogen production.