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Abstract
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This study focuses on the catalytic pyrolysis of bakelite using Halloysite clay, highlighting its significance in addressing the growing issue of plastic waste by converting it into valuable materials through an environmentally friendly process. Initially, bakelite pyrolysis was characterized to establish a baseline. The influence of Halloysite clay on pyrolysis kinetics and product yields was analyzed to inform industrial reactor design; kinetics were evaluated using Thermogravimetric analysis and Coats-Redfern modeling from 150-450°C, while thermodynamics were assessed with the Eyring equation. Thermogravimetric analysis of bakelite blend with Halloysite clay (2.5, 5, 7.5, and 10 wt%) was conducted at 20°C/min from 30 to 1000°C. Batch pyrolysis generates various products, with pyrolysis oil analyzed through Fourier transform infrared spectroscopy and Gas chromatography-mass spectrometry. The thermal degradation was conducted at 20°C/min, resulting in weight loss increasing from 56.49% to 62.57% with the addition of 5 wt% Halloysite clay. Bakelite degradation follows a 1.5th-order kinetic mechanism, with an initial activation energy of 81.088 kJ/mol and an Arrhenius constant of 4.39×10¹² min⁻¹; with 5 wt% Halloysite clay, activation energy decreases to 77.883 kJ/mol and the Arrhenius constant drops to 2.08×10¹² min⁻¹. Thermodynamic analysis revealed a decrease in enthalpy and Gibbs free energy with Halloysite clay addition. Pyrolysis of bakelite yielded 39.12% condensable products, 30.36% gas, and 30.52% residue, while the addition of 5% Halloysite clay resulted in 41.25% condensable products, 29.51% gas, and 29.24% residue. Fourier transform infrared spectroscopy and Gas chromatography-mass spectrometry analyses identified various compounds in the pyrolysis waxy oils, including alkanes, cycloalkanes, alkenes, cycloalkenes, aromatics, and oxygenated species. The findings demonstrate that Halloysite clay significantly alters bakelite pyrolysis kinetics, enhancing product yields and selectivity for valuable chemicals. This study underscores the novelty of Halloysite clay as a catalyst, highlighting its effects on thermal degradation, kinetics, and product distribution for optimal reactor design.
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