Efficient Low-temperature Hydrodeoxygenation of Fatty Acid Esters to Diesel-range Alkanes Over ReNi Bimetallic Catalysts

To mitigate global carbon emissions, utilizing bio-based oils instead of petroleum for biodiesel production has emerged as a viable strategy. However, the development of efficient catalysts for the mild conversion of fatty acid esters (the mainly compounds of oils or fats) into diesel-range alkanes remains challenging due to the low reactivity of carbonyl group in esters. Herein, we report an efficient catalyst system for the hydrodeoxygenation of fatty acid esters into diesel-range alkanes under mild conditions over the RemNin@SiO2 catalyst. The catalyst containing a Re/Ni molar ratio of 1.0 showed the best catalytic performance, a 100% conversion and 96.3% selectivity towards n-octadecane/n-heptadecane(C18/C17) were obtained when using the methyl stearate as model compound under mild condition (170 degrees C and 2.5 MPa H2 pressure), surpassing the catalytic performance of the most catalytic systems reported so far. Characterization results showed that the excellent catalytic performance of the RemNin@SiO2 catalyst was mainly attributed to the formation of ReNi alloy, which enhanced the interaction between the catalyst and the oxygen atom of carbonyl group of esters, thereby activating the carbonyl group and promoting the deoxygenation of fatty acid esters under mild conditions. In addition, the synthesized Re1Ni1@SiO2 bimetallic catalyst has good stability, and after four cycles, the catalyst still exhibits high catalytic performance with above 90% alkane conversion.Graphical AbstractRe1Ni1@SiO2 catalyzed the hydrodeoxygenation of Methyl Stearate towards alkanes (C18/C17) under mild conditions.