Effect of reduction temperature of NiMoO3-x/SAPO-11 on its catalytic activity in hydrodeoxygenation of methyl laurate
Ning Chena, Shaofeng Gongb, Eika W. Qiana
To develop a non-sulfide and non-noble metal catalyst for the one step deoxygenation and isomerization of methyl laurate to hydrocarbons that are identical to diesel fuel, a SAPO-11 supported reduced nickel and molybdenum catalyst was prepared, and its performance was investigated after reduction pretreatment at various temperatures (400–550 °C). For comparison, sulfided NiMo/SAPO-11, reduced NiO/SAPO-11 and MoO3/SAPO-11 were also studied. The reduction temperature exerted a significant influence on the deoxygenation activity, isomerization selectivity and deoxygenation pathway. The NiMo3-x/SAPO-11 catalyst that was reduced at a lower temperature (400 °C) exhibited low deoxygenation activity but the highest isomerization selectivity. However, the activity subsequently increased over the catalyst reduced at 450 °C, and was higher than that of the sulfided catalyst. In addition, the isomerization selectivity decreased with increasing reduction temperature. The high activity and isomerization selectivity are ascribed to the increase in the density of surface species of Mo4+ and Mo5+, respectively. With regard to the deoxygenation pathway, the catalyst reduced at 400 °C exhibited a high decarbonylation selectivity that was similar to the nickel-catalyzed reaction. In contrast, the synergetic effect of the nickel metal and Mo4+ species can be responsible for the high selectivity toward hydrodeoxygenation over the catalyst reduced at higher temperatures (450–550 °C).