Hydroconversion of fatty acids and vegetable oils for production of jet fuels

The review covers transformations of vegetable oils and fatty acids to jet fuel intensively studied during the recent years. A special emphasis is put on the liquid product yields and the product distribution with the latter one affecting the fuel properties. In addition, the desired catalyst properties have been summarized. One of the best results was reported for Jatropha oil processing, giving above 80 wt% yield of the liquid phase products over Ni supported on H3PW12O40/hydroxyapatite at ca. 400 degrees C under 30 bar hydrogen. Palm oil hydroconversion was performed in a two-step process over Pt/Al2O3 followed by Pt/HY, at 395 degrees C and 245 degrees C, respectively giving 54% jet fuel components. Typically also other products such as diesel range hydrocarbons are formed. Fatty acid and ester hydroconversion proceeds at lower temperatures, 255-260 degrees C over Ni supported catalysts producing above 50% yield of the aviation type fuel components. The desired catalyst contains acid sites with weak and medium strength, small metal particle sizes and mesoporosity, which facilitate diffusion of branched alkanes. Reaction kinetics, mechanism and kinetic modelling are also summarized.