Hydrodeoxygenation of sewer grease over Fe-Foam supported nickel-cerium oxides into hydrocarbon-derived fuel

Green diesel, a renewable fuel from organic waste and plant materials, offers an environmentally friendly alternative to traditional fossil fuels by significantly reducing greenhouse gas emissions and promoting sustainability. Consequently, the current investigation emphasizes the new studies on production of green diesel from fat, oil, and grease (FOG), colloquially known as sewer grease, through the hydrodeoxygenation (HDO) reaction utilizing a bimetallic modified iron foam catalyst identified as Ni_xCe_y/Fe-Foam. This catalyst was synthesized using a series of cerium loadings with a fixed amount of nickel (Ni_0.34Ce_0.30/Fe-Foam, Ni_0.34Ce_0.36/Fe-Foam, Ni_0.34Ce_0.42/Fe-Foam) via an electrodeposition method followed by H₂ annealing. Comprehensive characterization of the catalysts was conducted, revealing that most exhibited a surface area ranging from 0.35 to 45.13 m²/g, with an acid site density of 12 to 246 µmol/g. Notably, the presence of cerium species enhances the number of acid sites, facilitating the elimination of oxygen functionalities. Furthermore, the catalyst exhibited a distinct rosette-like morphology. In the context of the catalytic HDO screening conducted at 400 °C for 6 h, the Ni_0.34Ce_0.42/Fe-Foam (H₂) catalyst, enriched with cerium vacancy species, outperformed the other catalysts, achieving a HDO-derived liquid products yield of 87% and selectivity of 74% towards C₁₅ + C₁₇ and C₁₆ + C₁₈. This superior performance can be attributed to weak to medium acidity sites within the catalyst, which enhance its catalytic efficacy in the HDO process rather than being related to surface area characteristics.