Bifunctional MoS₂/TiO₂ Nanoparticles for Hydrodeoxygenation of Oleic Acid and Photodegradation of Carbonaceous Deposits

In this work, MoS2/TiO2 nanoparticles were investigated as a bifunctional catalyst for the conversion of oleic acid to diesel-range hydrocarbons and the removal of carbonaceous deposits on the catalyst surface. The entire series of catalysts with different mass loadings of MoS2 (5–20 wt %) was synthesized via a solvothermal method. MoS2/TiO2 nanoparticles had a high degree of MoS2 dispersion on anatase TiO2 support. The Brunauer–Emmett–Teller analysis reveals a marked increase in the specific surface area of 20 wt % MoS2/TiO2 (171 m2 g–1) compared to bare TiO2 (121 m2 g–1). For the catalytic conversion of oleic acid, it was found that the fraction of diesel-range hydrocarbons (C17–C18) in liquid products enhanced with increasing MoS2 mass loading. Moreover, the MoS2/TiO2 catalyst also presented high selectivity toward C18 hydrocarbons. This suggests that hydrodeoxygenation (HDO) was a dominant pathway for the catalytic conversion of oleic acid over MoS2/TiO2 nanoparticles. For the photocatalytic degradation, to clean up the MoS2/TiO2 catalyst after being used for the oleic acid conversion, hence, the photocatalytic removal of carbonaceous deposits on the surface was studied. The results demonstrate that carbonaceous deposits on spent MoS2/TiO2 were removed under UV-light irradiation due to the photodegradation property of the TiO2 support. Therefore, the active surface of the MoS2/TiO2 catalyst was simply recovered by a facile approach at room temperature.