(361b) Coupling of Ammonolysis and Pyrolysis to Upcycle Challenging Multilayer Plastic Films

Multilayer plastic films are complex materials containing distinct layers of materials including many types of plastics, aluminum, and paper. Each layer is added to confer a property to the film, such as a gas/vapor barrier, mechanical strength, or heat tolerance. Recycling technologies for multilayer materials are all at low readiness levels, with several technical hurdles still to be overcome for commercialization. In this work, we introduce a novel sequential chemical upcycling technology for multilayer materials, sequential ammonolysis and fast pyrolysis, which were used to process multilayer military meals ready-to-eat (MRE) food packaging with 4 distinct layers: 25-35% polyethylene (PE), 50-60% polyethylene terephthalate (PET) and polyamide (PA), and 10-20% aluminum. Being able to recycle MRE packaging would eliminate the costs and hazards associated with disposing of waste at a military base and potentially allow the military to recover value from a waste stream. Ammonolysis completely solubilized the PET and PA, converting them into monomers that were used as a feedstock for microbial growth to make single-cell protein powder. The PET and PA breakdown products were measured using HPLC to confirm complete solubilization of the PET and PA fractions in the mixed waste. The residual solids were subjected to pyrolysis to completely convert PE into wax, liquid, and gas products, which could be used in gaseous and liquid fuel blends, for power generation, and as lubricants, with the aluminum being recovered as a component of pyrolysis char. The pyrolysis products from the residual solids have comparable product quality metrics, including GC-MS, FTIR, CHNO, and metals analysis, to that of pure PE pyrolysis. Additionally, results will be reported on the ability of microbes to grow on the PET and PA breakdown products to produce single-cell protein. Preliminary results from culturing done with PET-degrading consortia and isolates reveal good growth on deconstructed products derived from brown and green MRE bags with cultures reaching optical densities in the 0.5 – 1 range as measured using spectrophotometry (600 nm).