Upgrading of Trimethylolpropane Oleate to Biojet Fuel Range Hydrocarbons Through Catalytic Deoxygenation

Utilising non-hydrogen environments to convert fatty acids to liquid fuels is potentially an economical, green and promising method for sustainable fuel production. This work focuses on solvent-free biojet fuel generation (C8 to C16) from the trimethylolpropane oleate (TMPE) using transition metal-loaded TiO2 as a solid acid catalyst. Wet impregnation was implemented to produce a series of TiO2-based cobalt, nickel, and iron catalysts with 2 wt.% metal loading without reduction. Each catalyst was tested for the deoxygenation of TMPE at 350 °C for 2 h at atmospheric pressure in a N2 atmosphere. It was found that using transition metal catalysts without reduction in a non-hydrogen environment could generate hydrocarbons with carbon chain lengths within the jet fuel range. The abundance of acid sites on the Fe catalyst helps break C-O bonds and facilitate the deoxygenation process. Fe/TiO2 exhibited the highest selectivity for C8 to C16 hydrocarbons (53.7 %) with relatively good deoxygenation performance (74.2 %). Although impregnation of transition metals resulted in reduction of specific surface area, the additional active sites were able to promote deoxygenation and breaking bond reactions to occur. The acidic sites provided by Fe metal and TiO2 carriers indicate that the catalyst is suitable for atmospheric nitrogen deoxygenation of TMPE for the preparation of biojet fuel. The result shows the potential of using a non-hydrogen environment to perform deoxygenation on long-chain fatty acid molecules to derive jet-fuel range hydrocarbons.