Catalytic hydrodeoxygenation of waste cooking oil into green diesel range hydrocarbons: From batch to continuous processing

• Green diesel production using batch and continuous reactors is studied. • Catalytic performance of Mo 2 C/CNF using stearic acid and real used cooking oil. • Higher Mo loading improves hydrodeoxygenation. • Yield of stearic acid to octadecane was 83 wt% (300 °C, 30 bar) in batch reactor. • HDO of waste cooking oil reached 82 wt% green diesel in continuous reactor. Green diesel produced via hydrodeoxygenation of oil and fat waste has emerged as a cleaner, higher quality product with better cold flow properties than traditional biodiesel. The development of non-sulfided catalysts for this process has attracted the attention of the research community. In this work, we demonstrate the potential of Mo 2 C catalysts supported on carbon nanofiber (CNF) in the HDO of used cooking oil. The effect of Mo loading and reaction temperature was analysed following an integrated approach: firstly, the catalyst performance was studied using stearic acid as a model compound in a batch reactor; then, the catalytic performance was evaluated in a trickled-bed reactor using waste cooking oil as feedstock. We demonstrated that the HDO of used cooking oil with Mo 2 C/CNF based catalysts was possible, obtaining high yields (86 mol %) to hydrocarbons in the range of green diesel. It was also stated that the direct HDO route was favoured over decarboxylation/decarbonylation routes. The catalytic performance obtained with different Mo containing catalyst was successfully correlated with the characterization results. The results gathered in this work represent a step forward in the use of Mo carbide catalysts in HDO processes and may pave the way for the deployment of this catalytic technology.