课题组近期采用金属氧化物(ZrO2、CeO2、La2O3和MgO)修饰γ-Al2O3,通过浸渍法制备负载量为10wt%的Ni基催化剂。以月桂酸甲酯为模型化合物,研究载体表面性质对Ni基催化剂油脂加氢脱氧(HDO)性能的影响,并采用H2-TPD、H2-TPR、BET、TEM、XRD、CO2-TPD、NH3-TPD和Py-IR等表征手段表征所制备的Ni基催化剂。结果表明,所制备的Ni基催化剂均具有大的比表面积(> 130 m2·g-1)和发达的孔道结构,助剂的引入对Ni物种的还原性有显著影响,并明显提高了所研究的Ni基催化剂对H2分子的低温“吸附-解吸”性能。经助剂修饰后,催化剂表面酸碱性发生明显改变,金属中心和酸位之间的协同作用,使Ni基催化剂能优先催化月桂酸甲酯发生脱羰/羧基(DCO)反应,产生C11烷烃;金属中心和碱位之间的协同作用,使Ni基催化剂能优先催化月桂酸甲酯选择性加氢反应,生成含氧化合物。经La2O3修饰的Ni基催化剂具有高的月桂酸甲酯转化率和含氧产物选择性,在反应温度为400℃、反应压力为2.0 MPa、H2/油比为500 N和LHSV为1.5 h-1时,月桂酸甲酯转化率为72.70%,含氧产物选择性达63.82%。
Shuang Chen(陈爽), Meijun Leng, Zhengjiang Liao, Jia Zeng, Hongmei Xie, Guilin Zhou*. Synergistic effects of surface acidity and alkalinity of Ni/γ-Al2O3 catalysts in fats and oils hydrodeoxygenation product distribution [J]. Industrial Crops & Products, 2024, 211, 118227.
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-Al2O3 catalysts were finely regulated by adding metal oxides (ZrO2, CeO2, La2O3, 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/La2O3/γ-Al2O3 catalyst showed the highest methyl laurate conversion (73%) and oxygen-containing product selectivity (64%) at 400 °C, LHSV = 1.5 h-1, H2/oil = 500 Nm3/m3, and PH2 = 2.0 MPa over the Ni/La2O3/γ-Al2O3 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.