Converting Plastic Wastes to Naphtha for Closing the Plastic Loop.

To solve the serious environmental problem and huge resource waste of plastic pollution, we report a tandem catalytic conversion of low-density polyethylene (LDPE) into naphtha, the key feedstock for renewable plastic production. Using β zeolite and silicalite-1-encapsulated Pt nanoparticles (Pt@S-1), a naphtha yield of 89.5% is obtained with 96.8% selectivity of C-C hydrocarbons at 250 °C. The acid sites crack long-chain LDPE into olefin intermediates, which diffuse within the channels of Pt@S-1 to encounter Pt nanoparticles. The hydrogenation over confined metal matches cracking steps by selectively shipping the olefins with right size, and the rapid diffusion boosts the formation of narrow-distributed alkanes. A conceptual upgrading indicates it is suitable for closing the plastic loop, with a significant energy saving of 15% and 30% reduced greenhouse gas emissions.