Promotional effect of Fe on performance of Ni/SiO₂for deoxygenation of methyl laurate as a model compound to hydrocarbons

Abstract

Ni/SiO 2 , Fe/SiO 2 and bimetallic FeNi/SiO 2 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/SiO 2 for the deoxygenation of methyl laurate, and FeNi(0.25)/SiO 2 with a Fe/Ni weight ratio of 0.25 showed the best activity. Moreover, the addition of Fe to Ni/SiO 2 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/SiO 2 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.

Catalytic deoxygenation of methyl laurate as a model compound to hydrocarbons on hybrid catalysts composed of Ni–Zn alloy and HY zeolite

“…For instance, Ni–Cu alloy was also found to show lower activity for methanation and C–C bond cleavage . Different from Cu having a minor effect on deoxygenation pathways, NiFe alloys favor hydrodeoxygenation (HDO) ascribed to the oxophilicity of Fe . Additionally, NiFe alloys are more active for deoxygenation but less active for C–C bond hydrogenolysis than metallic Ni.…”

“…Additionally, NiFe alloys are more active for deoxygenation but less active for C–C bond hydrogenolysis than metallic Ni. But, NiFe alloys is still very high active in methanation …”

“…13,14 Different from Cu having a minor effect on deoxygenation pathways, 13,14 NiFe alloys favor hydrodeoxygenation (HDO) ascribed to the oxophilicity of Fe. 15,16 Additionally, NiFe alloys are more active for deoxygenation but less active for C-C bond hydrogenolysis than metallic Ni. But, NiFe alloys is still very high active in methanation.…”

Hydrodeoxygenation of Fatty Acids, Triglycerides, and Ketones to Liquid Alkanes by a Pt–MoOx/TiO2 Catalyst

“…Among the three deoxygenation methods of fatty acids, hydrodeoxygenation, producing hydrocarbons without C−C cleavage of the fatty acid, is more atom‐efficient than the other methods (decarbonylation, decarboxylation) with C−C cleavage of the fatty acid. In previous studies, most of the supported metal catalysts, such as supported Pt, Pd, Ru, Rh, Fe, and Ni catalysts, suffer from high selectivity to decarbonylation or decarboxylation products rather than hydrodeoxygenation products even under H 2 . Few catalysts, including Ni‐loaded Hβ zeolite, Pt–Re/ZSM‐5, Pt/Nb 2 O 5 , Pd/Nb 2 O 5 /SiO 2 , tungsten‐ or molybdenum‐based catalysts, Ni–Mo/Al 2 O 3 , and hydrodesulfurization catalysts (sulfided NiMo oxides), catalyze the selective hydrodeoxygenation of fatty acids under pressurized H 2 .…”

“…In previouss tudies, most of the supported metal catalysts, such as supported Pt, Pd, Ru,R h, Fe, and Ni catalysts, suffer from high selectivity to decarbonylation or decarboxylation products rather than hydrodeoxygenation products even under H 2 . [6][7][8][9][10][11][12][13][14] Few catalysts,i ncluding Niloaded Hb zeolite, [16] Pt-Re/ZSM-5, [17] Pt/Nb 2 O 5 , [18] Pd/Nb 2 O 5 / SiO 2 , [19] tungsten-or molybdenum-based catalysts, [20][21][22][23] Ni-Mo/ Al 2 O 3 , [24] and hydrodesulfurization catalysts [25] (sulfided NiMo oxides), catalyze the selective hydrodeoxygenation of fatty acids under pressurized H 2 .H owever,m ost of these systems have some drawbacks such as decarbonylation and cracking as side reactions and the necessity of high catalyst loading or,i n other words, low turnover numbers (TONs). In our previous study, [18] we reported that Pt/Nb 2 O 5 showed a6 0times higher TON for hydrodeoxygenation of af atty acid than Ni-loaded Hb zeolite [16] and tungsten-or molybdenum-based catalysts.…”