Renewable routes to monomeric precursors of nylon 66 and nylon 6 from food waste

Abstract

Renewable chemicals, which could potentially replace crude oil-derived chemicals, have been receiving increased interest due to their environment-friendliness (i.e., carbon neutrality). Nylon 66 and nylon 6 are synthetic polymers that are widely used in daily life, synthesized by polycondensation of adipic acid and hexamethylenediamine (HMDA) and by ring-opening polymerization of epsilon-caprolactam, respectively. This review assesses catalytic productions of these three monomers from food waste. The food waste-based routes to the target compounds are analyzed separately and compared to conventional petroleum-based routes. Even though no commercially available methods to directly convert food waste into the target molecules exist, we have suggested emerging and promising catalytic routes via combined processes. The proposed pathways for the renewable production of adipic acid, HMDA, and epsilon-caprolactam are not yet fully competitive with petrochemical pathways due to higher costs and lower process efficiencies. However, considering that the renewable food waste-based routes are still being developed, their commercialization should happen soon.