Polystyrene depolymerization: Scavenging brominated flame retardants

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Polystyrene is a versatile polymer that is produced at enormous scale and applied in many consumer productsincluding packaging. Nonbiodegradable polymers, like polystyrene, represent an environmental burden;expanded polystyrene is among the most intractable components in municipal solid. The industry is now tryingto derive value from waste polymer and end-of life polymer for a feedstock. This drive reduces waste and hasan economic benefit because the material costs are lower than the costs of the petroleum feedstock. Thermalcracking and pyrolysis are among the several technologies to recover valuable monomers-the building blocksof polymers. In these processes, the polymer is heated to temperatures exceeding 400 oC and even beyond 600oC and the polymer decomposes to styrene (monomer) and hydrocarbons (benzene, for example).End-of-life polystyrene contains thermal stabilizers, brominated fire retardants, benzoyl peroxide, antimonytrioxide, among others. Brominated compounds accompany polystyrene consumer products to provide fireproof properties to meet UL or CSA fire resistance requirement. However, many of these compounds are nowbanned. Lavergne Group is a major Canadian company that recycles polymers but they must remove thebanned compounds. Together we will develop technology to scavenge the brominated compounds to meetfederal requirements. Removing these compounds reduces the burden of polystyrene to municipal landfills butwill maintain their supply of feedstock for their customers as they have a viable business operational.We will first measure the thermal properties of the polystyrene in a thermogravimetric analyser. This data willidentify the temperature range to conduct reactor tests to scavenge the bromine compounds. In the next step, wewill heat the polystyrene in a fluidized bed reactor and monitor the gas product composition. We will alsocondense the gases and analyse the aqueous phase in an HPLC analyser. Our GC-MS analyser will identify thecompounds of the organic phase. The third step will identify absorbents that we can add directly into thefluidized bed to scavenge the brominated compounds or to add a post-treatment step to capture them.