Catalytic Hydrodeoxygenation Of Biomass Lipids For Hydrocarbon Bio-diesel

Due to the incompatibility of first-generation bio-diesel(fatty acid methyl esters)with hydrocarbon fuels and high oxygen contents result in poor chemical stability,low energy density and high viscosity,to remove the oxygen of bio-diesel is alternative way via hydrodeoxygenation to produce diesel-like hydrocarbons.Diesel could be as an excellent fuel for heavy equipment with its high combustion calorific valueis,mainly consists of alkanes,alkenes and naphthenic with high carbon number.Animal and vegetable oils could be converted to alkanes via deoxygenation,decarboxylation or decarbonylation with its structures similar to the diesel-like hydrocarbons includes high carbon number.In this paper,we first explored one-pot hydrothermal catalytic deoxygenation of lipids under the condition of no external hydrogen over the simple noble metal Pd/C catalyst to achieve high heptadecane selectivity,achieved high carbon atom utilization.Currently,the research for producing bio-fuels focus on dry microalgae,but it needs more energy to remove the water from wet microalgae mainly accounts for 90% of the total energy in the bio-fuels production.Therefore,we have proposed a method for preparing aviation fuels by using water as a solvent,avoiding the high energy consumption.Simultaneously,it is based on the in situ hydrogen produced by catalytic hydrogen transfer(CTH)and aqueous phase reforming(APR)without external hydrogen,it eliminates the diffusion effect of hydrogen molecular for the rate of hydrodeoxygenation and accelerated the hydrodeoxygenation reaction.Thus,the hydrodeoxygenation reaction in situ hydrogen could be carried out under low temperature and pressure conditions,it reduces the requirement for high pressure resistant reaction apparatus because of higher reaction rate.In addition,we can also infer that the in situ hydrogen generated from solvents is more reactive than that from aqueous phase reforming because of different dehydrogenation capacity in solvents.Thus,we can achieve 100% conversion and the high yields of hydrocarbon diesel at12 hours with Pd/C catalyst under conditions that used water as solvent at 250 oC,oil/catalyst=4.25(weight ratio).The method for preparing aviation fuel without external hydrogen can be applied to convert lipids with high water contents directly into bio-diesel hydrocarbon with high efficiency and low energy consumption.In the second parts,the hydrodeoxygenation of triglycerides after hydrolysis or hydrogenolysis was analyzed.The specific mechanism of selective cleavage C-C or C-O bond in the hydrodeoxygenation reaction was explored.And discuss the selective cleavage of C-C and C-O bonds in the model reaction of fatty acid hydrodeoxygenation over SiO2,ZrO2 supported non-noble metal catalysts,such as Fe,Co,Ni,Cu.The selective cleavage the C-C and C-O bonds by the intrinsic properties of the catalysts was preliminarily discussed by a series of characterization methods such as BET,XRD,H2-TPR,XPS,H2-TPD,TEM,FT-IR and DFT.Based on some experiments,it can infer that the oxygen vacancies on the support surface may change the electron density of the metal and affects the style of hydrogen dissociation on the metal particle surface.Hydrogen dissociation such as hydrogen atoms,it would selective cleavage the C-C bond to form one less carbon hydrocarbon than the fatty acids.Otherwise heterolytic dissociation to form H?+,H?-and selective cleavage the C-O bond to produce fatty alcohols and it also was applied in bio-fuels,medicine,health and so on.