Upgrading Prosopis juliflora to biofuels via a two-step pyrolysis – Catalytic hydrodeoxygenation approach

Hydrodeoxygenation (HDO) upgrades prosopis juliflora biomass to liquid fuels. We pyrolysed prosopis juliflora to crude bio-oil with 55% oxygen and 10% bound water. NbMo/C catalytically hydrodeoxygenated bio-oil to upgraded oil, light oil, gas, and biochar. After 1 h at 300 °C and a catalyst/oil ratio of 0.05, the upgraded bio-oil yield reached 42%. Oxygen and moisture content dropped to 19% and 0.1%. The latter two properties were independent of temperature between 275 °C and 325 °C while yield was optimal at 300 °C. The upgraded oil fuel properties - viscosity (3.2 mm²/s at 40 °C), density (0.98 g/cc at 15 °C), HHV (30 MJ/kg), and stability at room temperature were improved after HDO. A GC–MS detected monomers (39% yield), one-third which were oxygen-free. The oil yield dropped 5% after 5 cycles. Coke contributed most to deactivation but air combusted it at 380 °C. NbMo/C is an efficient catalyst to upgrade bio-oil to bio-fuels.