In-situ deoxygenation of methyl palmitate to hydrocarbons on highly dispersed Ni–Re/TiO2 catalyst in aqueous phase using methanol as a hydrogen donor

Herein, TiO 2 supported Ni–Re alloy catalysts (i.e., NiRe(x:y)/TiO 2 , x:y denotes the Ni/Re atomic ratio) were prepared and tested for in situ deoxygenation of methyl palmitate to hydrocarbons in aqueous phase using methanol as hydrogen donor. Raman spectra indicates that there is interaction between NiO and ReO 4 − species via forming Ni–O-Re(=O) 3 species in the calcined catalysts, which contributes to the formation of Ni–Re alloy and promotes the Ni dispersion during the reduction with H 2 . Particularly, the Ni–Re alloy particles with average size of ∼1.4 nm highly disperse on spherical TiO 2 particles (∼14 nm in diameter) in NiRe(3:4)/TiO 2 (the nominal Ni content of 3  wt %). XPS reveals a charge transfer from metallic Ni to Re in the Ni–Re alloy. In in situ deoxygenation of methyl palmitate, compared with Ni/TiO 2 , NiRe(x:y)/TiO 2 give remarkably higher deoxygenation activity and lower activity for the C–C bond hydrogenolysis , ascribed to the synergistic effect between Ni and Re species and the geometrical effect of Re, respectively, which are further verified by propanoic acid-TPD and TPSR. The yield of C 6 ∼C 16 liquid hydrocarbons can achieve as high as 98.0% on NiRe(3:4)/TiO 2 at 330 °C. There is no obvious sintering of Ni–Re alloy and support TiO 2 particles during the recycling of NiRe(3:4)/TiO 2 , while the carbon deposition and the leaching of Re species slightly reduce the catalyst activity.