Integrated study of catalytic pyrolysis of bakelite waste: Catalyst variations, kinetic analysis, and batch pyrolysis

Abstract

Bakelite poses environmental and health hazards upon disposal, necessitating effective recycling strategies. This study explores catalytic pyrolysis of Bakelite using La₂O₃, CeO₂, and ZrO₂ (2.5, 5, 10 wt%) to assess kinetic, thermodynamic parameters and screen suitable catalysts. The maximum weight loss of Bakelite (62.91 wt%) was observed with 5 wt% La₂O₃. Kinetic analysis shows that Bakelite, with and without La₂O₃ (2.5, 5, and 10 wt%) follows a 1.5th-order mechanism, with activation energies of 83.09, 82.83, 75.43, and 83.41 kJ/mol, and Arrhenius factors of 4.39 × 10 ¹ ², 5.50 × 10 ¹ ², 1.88 × 10 ¹ ², and 4.05 × 10 ¹ ² min⁻¹ , respectively. For a 1.5th-order degradation, pure Bakelite showed ΔS = –0.05 kJ·K⁻¹ ·mol⁻¹ , ΔH = 76.42 kJ/mol, and ΔG = 104.80 kJ/mol; with 5 wt% La₂O₃, these shifted to –0.06 kJ·K⁻¹ ·mol⁻¹ , 72.75 kJ/mol, and 105.16 kJ/mol, respectively. Batch pyrolysis of Bakelite yielded 39.12 wt% condensable, 30.36 wt% gas, and 30.52 wt% residue, which shifted to 45.15, 31.56, and 23.29 wt% with 5 wt% La₂O₃, respectively. GC-MS of pyrolytic oil from bakelite without 5 wt% La₂O₃ showed alkanes, alkenes, aromatics, and oxygenates, including alcohols, ketones, ethers, and esters, while with 5 wt% La₂O₃, alkanes, alkenes, aromatics, and oxygenates like alcohols and esters were detected, confirmed by FTIR. This study proposes a novel catalytic pyrolysis of Bakelite using La₂O₃, CeO₂, and ZrO₂, integrating kinetic and thermodynamic analysis to enhance oil yield, selectivity, and resource recovery from a rarely explored bakelite.