Promotional effect of Fe on performance of Ni/SiO2 for deoxygenation of methyl laurate as a model compound to hydrocarbons

Ni/SiO2, Fe/SiO2 and bimetallic FeNi/SiO2 catalysts with different Fe/Ni weight ratios were prepared by incipient-wetness impregnation method for the deoxygenation of methyl laurate to hydrocarbons. It was found that a suitable amount of Fe enhanced the activity of Ni/SiO2 for the deoxygenation of methyl laurate, and FeNi(0.25)/SiO2 with a Fe/Ni weight ratio of 0.25 showed the best activity. Moreover, the addition of Fe to Ni/SiO2 significantly promoted the hydrodeoxygenation pathway to produce more C12 hydrocarbon and suppressed the activity for C-C hydrogenolysis. The effect of Fe on the performance of Ni/SiO2 is ascribed the formation of the NiFe alloy particles, particularly with the Fe-enriched surface at low Fe content, and the existence of oxygen vacancies in Fe oxides. A mechanism is proposed to explain the promoting effect of Fe, which involves the synergism between iron sites with strong oxophilicity and nickel sites with high ability to activate hydrogen. Besides, the effect of reaction conditions and catalyst stability were also investigated.