Production of renewable diesel by hydroprocessing of soybean oil: Effect of catalysts

► Effect of heterogeneous catalysts on hydroprocessing of soybean oil. ► NiMo, CoMo, Pd, Ni catalysts show good conversion (>90%). ► Isomerization and cracking are favored on CoMo. ► Decarboxylation is dominant on Pd while hydrodeoxygenation is favored on NiMo and CoMo. The effects of various supported catalysts on the hydroprocessing of soybean oil were studied. Several parameters were taken into account when evaluating the hydroprocessed products, including the conversion, selectivity (naphtha, kero/jet, and diesel), free-fatty acid content, oxygen removal, and saturation of double bonds. The hydroprocessing conversion order was found to be sulfided NiMo/γ–Al2O3 (92.9%)>4.29wt.% Pd/γ-Al2O3 (91.9%)>sulfided CoMo/γ-Al2O3 (78.9%)>57.6wt.% Ni/SiO2–Al2O3 (60.8%)>4.95wt.% Pt/γ-Al2O3 (50.8%)>3.06wt.% Ru/Al2O3 (39.7%) at a catalyst/oil weight ratio of 0.044. The most abundant composition in the liquid product was straight chain n-C17 and n-C15 alkanes when the Ni or Pd catalysts were used. Enhanced isomerization and cracking reaction activity on the CoMo catalyst may produce lighter and isomerized hydrocarbons. By combining gas-phase and liquid product analyses, decarboxylation was a dominant reaction pathway when the Pd catalyst was used, while hydrodeoxygenation was favored when the NiMo or CoMo catalyst was used.