Catalyst Metal-Ligand Design for Rapid, Selective, and Solventless Depolymerization of Nylon-6 Plastics

Developing effective catalysis to address end-of-life Nylon pollution is urgent yet remains underdeveloped. Nylon-6 is a resilient synthetic plastic and a major contributor to ocean pollution. Here, we report a metallocene catalytic system based on earth-abundant early transition and lanthanide metals that mediates Nylon-6 depolymerization at unprecedented rates up to 810 (..epsilon..-caprolactam) mol(Cat.)-1 h-1 at 240 degrees C in >/=99% yield. This solventless process operates with catalyst loadings as low as 0.04 mol% at temperatures as low as 220 degrees C - the mildest Nylon-6 depolymerization conditions reported to date. This metallocene catalysis can be carried out in a simulated continuous process, and the resulting ..epsilon..-caprolactam can be re-polymerized to higher-quality Nylon-6.