(25c) Production of Renewable Diesel and Jet Fuel from Thermal Deoxygenation (TDO) Oil

Demand for renewable fuels is projected to increase, and one of the most promising materials to convert into bio-oils is cellulose. Residue from logging, farming, or even municipal waste can be utilized as a potential feedstock. Several processes have been developed that convert cellulose into bio-oil, one of them being Thermal DeOxygenation (TDO). It is a process that converts organic acids from cellulose hydrolysis and dehydration into a low-oxygen bio-oil (< 5 wt %) with a broad boiling point distribution (75-550 °C). Additionally, the compounds can be upgraded into diesel and jet fuel fractions. However, catalytic hydrotreating and ring-opening reactions are required for TDO oil to meet the specifications for middle distillate fuels.

In this work, a mixture of levulinate and formate salts was converted to crude TDO oil in a pilot-scale continuous flow reactor at 450 °C and atmospheric pressure. Using a high-surface-area Ni catalyst (Ni/SiO₂-Al₂O₃), TDO oil was hydroprocessed to saturate aromatic rings and convert the oxygenated compounds in the fuel. This hydrotreated material was shown to have significantly better combustion characteristics, but improvements in the cetane number, hydrogen content, and density were needed to meet the requirements for No. 2 distillates and jet fuels.

For the ring-opening (endocyclic C-C hydrogenolysis) of hydrotreated TDO oil, several supported Ir catalysts were evaluated to produce high-cetane blendstocks. Ir catalysts with high activity and selectivity to desired products were chosen as candidates for scale-up reactions and the fuel was characterized and compared to fuel specifications. Using the catalysts presented in this research, we are able to produce renewable diesel and jet fuels that can be used as blending agents or as drop-in fuels.