Catalytic pyrolysis of wood-plastic composites using nickel-modified red mud for enhanced hydrogen and aromatic...

This study investigates the catalytic pyrolysis of wood-plastic composites (WPC) using nickel-loaded red mud (Ni/RM) catalysts to enhance hydrogen and aromatic hydrocarbon production. A series of Ni/RM catalysts with varying Ni loadings (5-20 wt%) were synthesized via impregnation method and used in the catalytic pyrolysis experiments of simulated feedstocks composed of low-density polyethylene and pinewood, and actual WPC samples in a fixed-bed reactor. Among these Ni/RM catalysts, 5%Ni/RM achieved the highest catalytic performance, increasing H₂ yield by 5.2 times (from 8.12 to 42.45 mL/g) and aromatic hydrocarbon selectivity by 4.4 times (from 1.37% to 6.05%) at 550 °C. Kinetic analysis revealed a 17% reduction in activation energy (from 65.23 to 54.38 kJ/mol) for catalytic pyrolysis, confirming enhanced reaction efficiency. The acidity and surface oxygen vacancies of the catalyst were identified as key factors in promoting deoxygenation, cracking, and aromatization reactions, as evidenced by temperature-programmed desorption and X-ray photoelectron spectroscopy characterizations. Moreover, the catalyst can be readily recovered and reused by magnetic separation. This study highlights the promising potential of waste-derived RM-based catalysts for the sustainable valorization of WPCs into high-value chemicals and fuels.