Catalytic upgrading of crude algal oil using platinum/gamma alumina in supercritical water

► Pt/γ-Al2O3 catalyzed the upgrading of crude algal oil to produce hydrocarbons in SCW. ► Lower water density and formic acid loading produced higher quality treated oil. ► SCW + HCOOH effectively controlled the coke formation. ► Reduction in surface area and micropore volume of Pt/γ-Al2O3 did not influence its activity. ► Hydrogenation, hydration, and oxygenation reactions occurred simultaneously.