Catalytic Pyrolysis of Waste Polystyrene Over Fe–B Composite Catalyst for Enhanced Liquid Fuel Production

ABSTRACT Healthcare derived polystyrene waste represents a growing and under addressed fraction of plastic waste streams due to contamination risks and limited recyclability. This study aims to investigate the valorization of waste polystyrene foam through catalytic and noncatalytic pyrolysis pathways to evaluate product yield distribution and identify the dominant chemical compounds formed under different reaction conditions. We introduce a novel, low‐cost catalytic pyrolysis strategy based on a thermally fused iron(II) sulfate‐boric acid composite catalyst (FBOC‐C) designed to enhance liquid fuel recovery under simple distillation mood reactor separation. Systematic temperature and residence time optimization has identified 500°C and 30–45 min as optimal conditions for efficient depolymerization. Compared to noncatalytic and single catalytic systems, the composite catalyst achieved the highest liquid yield of 91.3%, with markedly reduced residue to 8.3% and gas formation of 0.4%. Fractional distillation demonstrated superior volatility control, with enhanced recovery of fuel relevant reaction across 80°C–360°C. GCMS analysis confirmed a progressive increase in aromatic selectivity from noncatalytic (78.83%) to FBOC‐C catalyzed oil (93.02%). Structural and morphological characterization (XRD, SEM, EDX, and TGA) revealed a hybrid crystalline amorphous catalyst architecture responsible for synergistic redox acidic interaction that suppresses secondary polymerization and excessive cracking. Unlike conventional zeolite or noble metal‐based systems, this approach integrates economical catalyst synthesis with simple pyrolytic distillation, offering a scalable and energy efficient pathway for high yield fuel production from healthcare polystyrene waste.