Hydrotreating of C9 Oxygenates Under Supercritical Reaction Conditions

The use of bio-oils as transportation fuel has been limited due to stability and quality issues caused by oxygenated groups. The oxygen content may be reduced by hydrodeoxygenation to produce hydrocarbons and water from bio-oil (Babu, 2008). The water is immiscible with the hydrocarbons and partitions completely into a separate phase. The resulting hydrocarbon layer may then be used for processing to transportation fuels in conventional refineries. To perform such hydrotreating at mild pressures, supercritical hydrogenation of model bio-oil oxygenates was investigated. The Pt/Al2O3 - catalyzed hydrogenation of nonanal was investigated in supercritical hexane in a fixed bed reactor at 300°C and pressures of 30-50 bar with a stoichiometric excess of H2 to produce nonane. Other products were liquids nonanol and octane as well as light gases. The product profile at various operating conditions and preliminary conclusions are presented regarding the effectiveness of the proposed hydrotreating approach.