Effect of support properties on product selectivity in aqueous-phase Fischer–Tropsch synthesis over Ru catalysts

The effect of support properties on 5 wt% Ru catalysts was investigated during aqueous-phase Fischer–Tropsch synthesis (FTS) over H-ZSM-5, SiO 2 -Al 2 O 3 , ZrPO x , TiO 2 , ZrO 2 , and γ-Al 2 O 3 at 150 °C using a H 2 /CO ratio of 2 and an initial pressure of 3.0 MPa. Ru/SiO 2 -Al 2 O 3 showed high activity (7.5 mol CO mol Ru −1 h −1 ) and the highest chain growth probabilities (α = 0.93) for both hydrocarbons and oxygenates. Product selectivity varied strongly with acid strength, with stronger acid sites suppressing oxygenate formation and shifting the product distribution toward hydrocarbons. Ru/H-ZSM-5 completely suppressed oxygenate formation in both aqueous and cyclohexane media and exhibited comparable normalized hydrocarbon formation rates, yielding 46.0% selectivity to jet-fuel-range paraffins (C 8 –C 16 ). Ru/H-ZSM-5 also showed the highest normalized CO consumption rate. These results demonstrate that support acid strength influences product selectivity in aqueous-phase FTS and enables selective synthesis of jet-fuel-range hydrocarbons over Ru catalysts.