Abstract

To reduce dependence on fossil fuels and limit their environmental impact, the development of biofuels represents an effective strategy. Green diesel is a biofuel synthesized from vegetable oil that is fully compatible with conventional diesel engines and therefore represents a promising alternative to mineral diesel. In addition, the use of waste-derived catalysts can further improve the sustainability of the process. In this study, fly ash cenospheres (FAC), an abundant industrial waste, were used as a support to synthesize several transition-metal-based catalysts. The catalysts were tested for the catalytic deoxygenation of vegetable oils in a batch reactor at 320 °C and 40 bar H2 using 10 wt% catalyst and n-hexane as the solvent. Among the tested catalysts, NiMo(5/15)/FAC exhibited the best performance, achieving complete conversion and producing a biofuel containing 91.7% C15–C18 hydrocarbons. The physicochemical properties of the catalyst were investigated using ICP-MS, FT-IR, XRD, and BET-BJH analyses. The effects of the solvent, feedstock, and catalyst reuse were also evaluated. In the recycling tests, the catalyst activity rapidly decreased; however, the regeneration step fully restored its catalytic performance. These results show that FAC can be effectively valorized as a catalyst support for green diesel synthesis.

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