Polypropylene\nDecomposition in Hydrocarbon Solvents:\nZeolite-Catalyzed Chemical Recycling

Chemical recycling of waste plastics into valuable chemical\nfeedstocks,\nspecifically targeting C<sub>3</sub>–C<sub>4</sub> gas products\nand naphtha fraction ranging from C<sub>5</sub>–C<sub>9</sub> products, was explored in this study. Our approach involves melting/dispersing\npolypropylene in a hydrocarbon solvent and decomposing it using a\nzeolite catalyst. This technique effectively reduces the viscosity\nof molten plastics, enhances heat transfer, and allows the easy separation\nof inorganic fillers via filtration. Comprehensive analytical methods\nare used to identify and differentiate various decomposition products,\nincluding aliphatic hydrocarbons, monocyclic and polycyclic aromatics,\nand heavier hydrocarbons, distinguishing them from those derived from\nthe solvent. The product distribution was thoroughly analyzed using\na suite of techniques, including gas chromatography, two-dimensional\ngas chromatography, distillation gas chromatography, gel permeation\nchromatography, and thermogravimetric-differential thermal analysis.\nOur results highlight the effectiveness of using <i>n</i>-hexadecane and zeolite beta, achieving a remarkable 60 wt % yield\nof naphtha fraction (C<sub>5</sub>–C<sub>9</sub>) from polypropylene\ndecomposition at 400 °C.