NiCu Anchored on a Specific TiO2 Face Tunes Electron Density for Selective Hydrogenation of Fatty Acids into Alkanes or Alcohols

Catalyst design is critical for renewable selective hydrogenation of fatty acids into alkanes or alcohols, especially for active metals and supports. We demonstrate that NiCu anchored on a TiO2 (P25) surface, prepared by the impregnation method, performed superior temperature-sensitive catalytic activities with a higher fatty alcohol yield of 78.2% (205 °C, 4 MPa H2, and 12 h) and alkane yield of 85.0% (245 °C, 3 MPa H2, and 6 h). X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) suggest that Ni or NiCu anchored on rutile with oxygen vacancies can achieve reversal of charge transfer between the metal and TiO2 support. Especially, the normal NiCu cluster loading on the rutile surface can improve the dispersion of the NiCu cluster and oxygen vacancy concentration. Thus, more NiCu clusters anchored on oxygen defects can obtain negative charges in favor of alcohol production. In contrast, the other active NiCu clusters will preferentially cleave the C–C bond to produce alkanes at a higher reaction temperature. Our work provides a new strategy for designing highly effective hydrogenation catalysts.