Interfacial Auδ−–OV–Ti Structure Promoted C–H Bond Activation for Selective Oxidation of Fatty Alcohols to Fatty Acids

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Oxidation of fatty alcohols to fatty acids is still challenging due to the sluggish activation of the C–H bond over Au supported on reducible oxides with a coordination-saturated structure. Herein, we constructed an efficient interfacial Auδ−–OV–Ti structure by tuning the crystal forms of TiO2. Compared with TiO2-rutile exposed by (110) and (111) crystal facets, TiO2-anatase can exploit the defect (101) crystal facet to obtain rich oxygen vacancies (OV), inducing electron migration from TiO2-anatase support to Au species to form electron-rich Auδ− species. Specifically, the synergistic catalytic effect between the OV–Ti and Auδ− species greatly enhances the adsorption of alcohol and thereby overcomes sluggish activation of the C–H bond caused by the electron pushing effect triggered by long carbon chains. Consequently, the Au/TiO2-anatase catalyst shows excellent isooctyl alcohol conversion (69.5%) and isocaprylic acid selectivity (67.9%) under base-free conditions. The catalytic system is further extended to the oxidation of other fatty alcohols to fatty acids with excellent catalytic performance.