Advances in the Application of Low-Cost, Natural Materials, and Waste-Derived Catalysts for Catalytic Upgrading of Plastic and Biomass Pyrolysis Oil

Unprecedented levels of population growth, urbanization, and industrialization have occurred in the 21st century, and with them has come an increase in demand for energy as well as a rise in the production of solid and plastic wastes. Heterogeneous catalysts designed from abundant and readily available solid waste provide a sustainable recycling strategy for industrial-scale applications. Nonetheless, the impact of purification techniques and raw material compositions may aid in tailoring the development of a robust catalyst for specific applications. Waste-derived catalysts have demonstrated capability in biofuel refining applications such as biodiesel synthesis, pyrolysis of lignocellulosic biomass, and waste plastic into oils. The first part of this review focuses on metal oxides that make different solid wastes viable for catalyst design and development, and the second and third parts cover the application of waste-derived catalysts in the catalytic upgrading of waste plastic and lignocellulosic biomass pyrolysis oils into fuels. For the industrial scalability of these waste-derived catalysts, their activity, stability, reusability, and regenerability in the context of upgrading oils derived from the pyrolysis of biomass and waste plastics were critically evaluated. Waste-derived heterogeneous catalysts were found to perform comparably to conventional industrial catalysts such as zeolite-based and hydrotreating (e.g., Ni-Mo/Al₂O₃) catalysts. Particularly, Red mud-derived catalyst has demonstrated cost-effectiveness and sustainable catalytic upgrading of bio-oil and waste plastic pyrolysis oil into fuel-range hydrocarbons (28-40 wt % gasoline, 35-50 wt % diesel fractions, and chlorine content less than 0.1 wt %). This research promotes the design and development of heterogeneous catalysts from industrial, municipal solid waste, biomass and agricultural residues, eggshells, seashells and bones, and e-waste by combining synthesis and purification methodologies to recover mixed metal oxide materials to bridge existing supply gaps. Consequently, their applications in the catalytic upgrading of oil produced from the pyrolysis of waste plastics and lignocellulosic biomasses into fuels offer economic, environmental, and energy security benefits.