Nickel-based catalysts for plastic pyrolysis: advances in product selectivity, yield optimization, and emerging pathways for thermochemical recycling

Abstract

The rapid increase of plastic waste presents a pressing environmental concern which necessitates the development of advanced catalytic technologies for sustainable polymer upcycling. Catalytic pyrolysis offers a thermochemical route for converting plastic polymers into fuels, aromatics, olefins, and functional carbonaceous materials under controlled and energy-efficient conditions. Among catalytic systems, nickel-based (Ni-based) catalysts have demonstrated high potential due to their strong C–C and C–H bond cleavage ability, hydrogenation–dehydrogenation reactions, and synergistic interactions with support materials. This review uniquely integrates catalyst mechanistic insights with design strategies to establish a foundation for understanding and optimizing Ni-based catalytic plastic pyrolysis. The work emphasizes advances in reaction mechanisms and catalyst design principles, and influence of catalyst support acidity, porosity, redox properties, metal–support interactions, and Ni dispersion on product selectivity and yield. This provides a level of depth not covered in previous reviews. A central innovation of this work is the systematic comparison of monometallic, bimetallic, and trimetallic Ni catalysts, linked to their roles in bond activation, coke suppression, and targeted production of hydrogen, aromatics, and carbon nanotubes. Additionally, this review offers a comprehensive evaluation of catalyst deactivation mechanisms, including sintering, coking, and phase transformation, and correlates them with regeneration strategies to guide long-term catalyst stability. Emerging frontiers including microwave-assisted Ni catalysis, photothermal activation, and AI-guided catalyst screening are also critically assessed to highlight transformative opportunities for next-generation catalyst design. By integrating current advances with mechanistic insights, this review provides a novel roadmap for developing high-performance, sustainable Ni-based catalysts for polymer waste valorisation.