Advanced H-Beta Zeolite Catalysis for Selective Benzene Production from Sulfur-Containing PPS Plastic Waste

Efficient recycling of sulfur-containing plastics into valuable aromatic hydrocarbons is crucial for sustainable waste management. Herein, an in situ catalytic hydro-pyrolysis strategy using cost-effective H-beta zeolite is developed to selectively convert polyphenylene sulfide (PPS) waste into benzene. Under optimal reaction conditions (600 °C, 0.3 MPa H2, and catalyst-to-feed ratio = 0.7), PPS conversion reached 73%, with benzene selectivity exceeding 99.8% and complete sulfur removal. Mechanistic analyses revealed a stepwise hydrodesulfurization pathway in which sulfur-containing intermediates are progressively hydrogenated and eliminated as H2S. Density functional theory (DFT) calculations further demonstrate that efficient desulfurization arises from selective C–S bond cleavage, driven by strong electrostatic and frontier orbital interactions between sulfur species and the Brønsted acid sites of H-beta. This integrated experimental–theoretical study establishes a sustainable and economically attractive route for the clean valorization of sulfur-rich plastic wastes into high-purity aromatics.