Catalytic hydrothermal liquefaction of Spirulina over bifunctional catalyst to produce high-quality biofuel

•Five different bifunctional catalysts are characterized and applied for the HTL of Spirulina.•The XRD, NH3-TPD and BET analysis results show NiO/SAPO-34 and NiO/USY catalysts have the relatively superior properties.•The bio-oil contains the highest HHV (34.58 MJ/kg) and the most hydrocarbons (20.58%) with NiO/USY catalyst.•NiO/USY can promote the macromolecular-cracking reaction and the formation of light oil components in the HTL.