Synergistic effects of surface acidity and alkalinity of Ni/γ-Al2O3 catalysts in fats and oils hydrodeoxygenation product distribution
Shuang Chen, Meijun Leng, Zhengjiang Liao, Jia Zeng, Hongmei Xie, Guilin Zhou
Abstract
The deep utilization of green and renewable chemicals has laid the foundation for sustainable development. Recombining and modifying the long carbon chain structure and oxygen-containing functional groups in fats and oils can prepare important chemical products, such as high-quality second-generation biodiesel and oxygen-containing compounds (fatty alcohols, fatty acids, and esters). To improve the hydrodeoxygenation (HDO) performances of Ni-based catalysts, the effect of surface composition was studied in detail. Acid-base centers of Ni/γ-Al 2 O 3 catalysts were finely regulated by adding metal oxides (ZrO 2 , CeO 2 , La 2 O 3 , and MgO). It was found that enhancing the basicity of the studied catalyst was conducive to the methyl laurate conversion, but was not conducive to the HDO of oxygen-containing intermediates. In other words, the strong basicity would promote the condensation reaction of oxygen-containing intermediates over Ni-based catalyst. Among the studied catalysts, Ni/La 2 O 3 /γ-Al 2 O 3 catalyst showed the highest methyl laurate conversion (73%) and oxygen-containing product selectivity (64%) at 400 °C, LHSV = 1.5 h −1 , H 2 /oil = 500 Nm 3 /m 3 , and P H2 = 2.0 MPa over the Ni/La 2 O 3 /γ-Al 2 O 3 catalyst. The acidity was favorable to improve the conversion of oils and the yield of alkane products, and the basicity was favorable to obtain oxygen-containing compounds over the corresponding catalysts.