Improved Styrene Yield from Thermocatalytic Disintegration of Waste Styrofoam over Ceria Nanospheres

The widespread use of plastics in modern societies results in enormous amounts of polystyrene waste (styrofoam), which is nonbiodegradable and challenging to process and dispose of. To attain sustainability and a circular economy, scientists are now searching for methods to recycle styrofoam waste into its monomer. At the same time, it is critical to address issues such as low activity and selectivity of styrene during thermal pyrolysis. Cs-promoted Cr/CeO2 catalyst shows superiority in terms of the absolute yield of styrene to traditional thermal pyrolysis. Catalytic depolymerization always promotes the formation of ethylbenzene, where Cr acts as a dehydrogenating entity and dehydrogenates the ethylbenzene back to styrene. Given the crucial styrene yield and the separation problems in recycling polystyrene (styrofoam), bifunctional catalysis, like CsCr3/CeO2, holds great promise for the future of plastic chemical recycling and upcycling. The surface properties and local geometry were investigated by using X-ray absorption spectroscopy (XAS), revealing that cubic structured Ce species were reduced from Ce3+ and Ce4+ oxidation states during catalysis with Cs.