Oxidative Upcycling of Polyethylene to Long Chain Diacid over Co-MCM-41 Catalyst.

Plastic pollution is an emerging global threat due to lack of effective methods for transforming waste plastics into useful resources. Here, we demonstrate a direct oxidative upcycling of polyethylene into high-value and high-volume saturated dicarboxylic acids in high carbon yield of 85.9 % in which the carbon yield of long chain dicarboxylic (C10-C20) acids can reach 58.9% over cobalt-doped MCM-41 molecular sieves, in the absence of any solvent or precious metal catalyst. The distribution of the dicarboxylic acids can be controllably adjusted from short-chain (C4-C10) to long-chain ones (C10-C20) through changing cobalt loading of MCM-41 under nanoconfinement. Highly and sparsely dispersed cobalt along with confined space of mesoporous structure enables complete degradation of polyethylene and high selectivity of dicarboxylic acid in mild condition. So far, this is the first report on highly selective one-step preparation of long chain dicarboxylic acids. The approach provides an attractive solution to tackle plastic pollution and a promising alternative route to long chain diacids.