Impact of Large-Scale Recycling of Polyethylene, Polystyrene, and Poly(ethylene terephthalate) on the Structure of Chemical Manufacturing in the United States

A network model of the U.S. chemical manufacturing industry was used to assess at what cost points, and the extent to which, products from depolymerization of polyethylene (PE), polystyrene (PS), and poly(ethylene terephthalate) (PET) might find markets in the current U.S. chemical manufacturing industry. Incorporating the pyrolysis of PE to yield light alkanes and alkenes, the depolymerization of PS to yield styrene, and the methanolysis of PET into a network model of U.S. chemical manufacturing led to changes in large numbers of processes, and in all cases, the capital cost requirements for expanding capacity to effectively utilize the recycled materials were greater than the capital required for the recycling process. For PS and PE, all available waste plastic, up to at least 5 million tons/yr, can be utilized. In contrast to PE and PS recycling, recycled PET had limits to its utilization because the PET recycling process required a feed material along with the waste plastics (methanol), and the recycling led to products (dimethyl terephthalate and ethylene glycol) that were not dominated by the monomers used to manufacture the plastic. Collectively, these findings highlight the importance of understanding how products from the chemical recycling of individual plastics will be utilized.