Preparation And Hydrodeoxygenation Activity Of Novel Multistage-porous Supported Bi-metal Catalysts

Bio-oil upgrades to produce liquid fuels are currently the most promising alternative to fossil fuels.Carboxylic acid compounds are an important part of bio-oil.Inestigating the hydrodeoxygenation reaction of carboxylic acid compounds is an important issue for studying the mechanism of hydrodeoxygenation of bio-oil.In this thesis,octanoic acid was used as a model compound to study the hydrodeoxygenation reaction of medium and long chain carboxylic acids,and to screen out high-efficiency catalysts.The S-MCF-X foam was synthesized by hydrothermal method using potassium chloride as the pore expander.The effect of the inorganic salt potassium chloride content on the pore structure of the foam was investigated.The experimental results showed that,the surface of S-MCF-X exhibited a larger pore size,a smaller specific surface area and a looser surface structure with the increase of potassium chloride content.The NiMo/S-MCF-X and NiMo/MCM-41 catalysts prepared by impregnation method were applied in the hydrodeoxygenation of octanoic acid to investigate the effects of different supports.The experimental results showed that the NiMo/MCM-41catalyst were more favorable for the hydrodeoxygenation of octanoic acid,wherein the conversion of octanoic acid was 95.8%,and the selectivity of octane and heptane were65.2%and 28.6%,respectively.A serias of NiMo/MCM-41 catalysts with different Ni/Mo ratios were prepared by impregnation method and applied to the hydrodeoxygenation of octanoic acid.The effects of the ratio of Ni/Mo,the reaction temperature,the reaction pressure and the reaction time on the hydrodeoxygenation of octanoic acid were investigated.The experimental results indicated that Ni is beneficial to the multiple hydrogenolysis of C-C bonds.Mo not only promotes the reduction and dispersion of nickel metal oxides,but also enhances the hydrodeoxygenation activity of bimetallic Ni-Mo catalysts.At the same time,Mo is beneficial to the dehydration-hydrogenation of octanol and promotes the hydrodeoxygenation of caprylic acid to form C₈ alkanes.The results also showed that 3Ni7Mo/MCM-41 catalyst showed the highest reaction activity.The conversion of octane was 96.1%,and with 72.6%and 26.6%of octane and heptane selectivity respectively under the conditions of reaction temperature 270°C,reaction pressure 3 MPa and reaction time 7 h.NiMoW/MCM-41 catalyst was prepared by impregnation method and applied in the hydrodeoxygenation of octanoic acid.The effects of W content,reaction temperature,reaction pressure and reaction time on the hydrodeoxygenation of octanoic acid were studied.The results showed that the introducing of W could improve the selectivity of hydrodeoxygenation.NiMoW/MCM-41?5 wt.%?catalyst had the best reaction activity.Under the conditions of reaction temperature 270°C,reaction pressure3 MPa and reaction time 7 h,the conversion of octane was 97.1%,the selectivity of octane and heptane were 72.0%and 25.8%,respectively.