MAINSTREAM ENGINEERING CORP SBIR Phase I Award, July 2023

Approximately 380 million tons of plastic is produced every year and over 75% of plastic is discarded as waste after a single use. Only 8% of waste plastic is recycled and 76% is landfilled. Many plastics are simply unrecyclable and many products use multiple materials that prevent recycling. Moreover, recyclable plastics need to be free of contaminants, but cross-contamination from polymer mixtures and additives is common. As a result, recycled plastics are often low value with less desirable properties. Gasification represents a feedstock agnostic process that can convert plastic and other wastes into a syngas that can be upgraded to fuels and chemicals. However, gasifying halogenated plastics (e.g., PVC) will produce harmful gases (e.g., hydrochloric acid, chlorine gas, and dioxins) that should not be released to the environment. Existing post-gasification treatment methods are expensive. Therefore, we need to develop feedstock pretreatment methods to remove chlorine prior to gasification. Our hydrothermal pretreatment process has the capability to preferentially remove chlorine from mixed plastics and produce a feedstock ideal for gasification processes.