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Hydrogenative Depolymerization of Polyesters Catalyzed by a PN3-Ruthenium Complex Using Both H2 and EtOH as Hydrogen Sources

Science & Technology Indonesia 2025
Rao Yiwei, Ruiqin Wang, Li Chen, Peng Yanqin, Yang Weiran, Zhongbao Jian, Changguang Yao

Summary

Researchers developed a ruthenium-based catalyst that depolymerizes polyesters—including PLA and PET—into reusable diols under mild conditions, with PLA breaking down at room temperature and just 1 MPa hydrogen pressure, enabling selective upcycling of mixed plastic waste including polyolefins.

Polymers

Selective hydrogenative depolymerization of polyesters to diols is regarded as a promising strategy for plastics upcycling. However, many catalysts documented in literature still involve harsh reaction conditions, such as high temperature and high H2 pressure. In this work, we present a PN3-ruthenium complex catalyzed polyesters upcycling into various highly value-added diols under mild reaction conditions using H2 as a hydrogen source. It is worth noting that PLA depolymerizes into 1,2-propanediol under 1 MPa hydrogen pressure at ambient temperature within 2 h; the conditions are much milder than those of previous reports. Aromatic polyester PET degradation needs harsher reaction conditions (80 °C, 4 MPa, 3 h). The different reaction conditions enable direct separation of the degradation products of PLA and PET mixture via sequential depolymerization, as well as mixing them with polyolefins (PE, PP, PS). More strikingly, this catalyst is also effective for the catalytic hydrogenation of polyesters in the presence of ethanol to afford various diols, avoiding the use of harsh reaction conditions and an expensive autoclave.

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