Green Reduction of Bauxite Residue to Iron Zero Based Catalyst for Hydrothermal Liquefaction of Municipal Solid Waste

Industrial and municipal wastes remain significant sources of air, soil, and water pollutions and thus causing adverse climate and health impacts. EU faces challenges in developing green recycling processes and reducing GHG emissions. To tackle the raw material dependency, GHG emissions, industrial and urban wastes management, EU needs comprehensive cost effective and environment friendly strategies for the efficient use of scarce resources for the green manufacturing of more economical and high-quality materials. Innovation in green catalysis is a key driver towards the fulfilment of these goals. Landfilled industrial residues such as bauxite residue (BR) can provide major amounts of critical metals such as iron, which can be used to generate catalyst for making catalysis driven chemical processes more cost effective and environmentally friendly. Unlike conventional chemical methods and chemical based reducing agents for the reduction of metal oxides present in BR, the use of municipal waste as reducing agent to reduce BR to catalytically active metal will be a radical change in existing catalysts synthesis processes. Due to redox catalytic properties, the resulting reduced metals can be used as hydrogenation catalysts (i.e., in situ generated hydrogen from water) for the hydrothermal conversion of biomass to improve the yield and quality of biocrude intermediate. The resulting biocrude would be easily integrated into the refinery streams (e.g., fossil crudes and gas oils etc.) for the sustainable refinery processes. Furthermore, the in situ generated hydrogen can also be used to produce syngas from CO2 and CO gases, which are usually produced during the conversion of biomass. Therefore, a new greener path of sustainable catalysts production through transforming hazardous wastes for sustainable and ecofriendly chemical processes could be achieved.