(370d) Production of Biorenewable Thermal Deoxygenation Oil and Upgrading to Diesel and Jet Fuel Range Hydrocarbons

Thermal DeOxygenation (TDO) is a novel non-catalytic thermochemical process which converts neutralized biomass acid hydrolysate into synthetic crude oil at 450 °C and atmospheric pressure. TDO oil is highly stable and has a very low oxygen content (< 5 wt %) and a low total acid number (TAN) compared to pyrolysis oil. Certain properties of the TDO oil such as broad boiling point range (75-550 °C) and high aromaticity allow it to be compatible with existing petroleum refinery operations and petroleum products. In this study, crude TDO oil was produced from a mixture of levulinate and formate salts using a pilot scale continuous flow reactor, and upgraded and fractionated to produce gasoline, jet fuel, and diesel range hydrocarbons.

Crude oil was hydrogenated to remove residual oxygen and increase hydrogen content of the oil using a commercial Ni/SiO₂-Al₂O₃ catalyst in bench scale continuous flow tubular reactors. The crude and hydrogenated TDO oils were distilled to produce jet fuel (180-250 °C) and diesel (150-325 °C) range hydrocarbons using a fractional distillation apparatus according to American Society for Testing and Materials (ASTM) standards. Four different TDO oil blendstocks (crude TDO oil, Hydrotreated TDO oil, distilled TDO oil, and distilled Hydrotreated TDO oil) were analyzed for chemical and physicochemical properties following ASTM standard methods. Properties of the TDO fuels were compared with ASTM and military fuel standards (MIL-DTL), and blended appropriately to meet the specifications. TDO diesel blendstocks were blended with Ultra Low-Sulfur Diesel (ULSD) in four different volume percent (5 %, 10 %, 15%, and 20%) to produce sixteen different fuel blends. Combustion and emission behaviors of the fuel blends were studied using an air-cooled single-cylinder diesel engine.

Fuel properties such as hydrogen content, specific gravity, viscosity, and net heat of combustion of TDO oil could be improved with hydroprocessing. Jet fuel and diesel fractions of hydroprocessed TDO oils meet all fuel specification with a few exceptions (density, hydrogen content, and heating value for jet fuel and cetane number for diesel). Fuel blends prepared with hydrotreated TDO oil and ULSD exceed or fall within the specified range of fuel specifications. Results show that the TDO oil is a potential renewable fuel as well as a blending agent for making fuel blends with petroleum products.