Bio-Jet Fuels Production By Selective Hydrogenolysis Of C-O Bond Of Higher Alcohols Derived From Bio-Ethanol

Jet fuel is a kind of aircraft fuel refined from petroleum as raw material.The non-renewable nature of petroleum and our country’s oil-less energy structure have forced our country to develop green and renewable bio-jet fuel.Nowadays,the existing bio-jet fuel routes include oil-to-oil,gas-to-jet,alcohol-to-jet,sugar-to-jet.But problems such as catalyst deactivation,poor product selectivity,poor product carbon number distribution and high cost still hindering their commercial application.With the rapid expansion of electric energy vehicles in our country,the only remaining application of ethanol blending gasoline will be facing great pressure in the future.On the basis of the huge yield of ethanol,the development of high-value applications of ethanol can not only match with the current ethanol industry to ensure the stable and healthy development of the bioethanol industry,but also help to enrich our country’s energy structure and ensure national energy security.The purpose of this study is to develop a new technical route for the preparation of bio-jet fuel from ethanol.In the study,2-ethyl-1-hexanol was used as a model compound,and the catalytic activity and product selectivity over several molybdenum-based catalysts were investigated.Catalysts such asβ-Mo₂C,α-Mo C,Mo O₃ were prepared by temperature programmed reduction（TPR）,and the physicochemical properties and texture properties of the catalysts were characterized and tested by XRD,BET,HR-TEM,XPS,NH₃-TPD,etc.Analysis was carried out,and different higher alcohols and mixtures were used as feedstocks to study the adaptability of 2%Co-Mo₂C in the hydrodeoxygenation of higher alcohols with different molecular structures.At the same time,the kilogram-scale ethanol coupling,product separation and higher alcohol hydrodeoxygenation were also carried out to verify the feasibility of the ethanol-to-jet fuel route starting from ethanol coupling.The main conclusions are as follows:1.Screened molybdenum-based catalysts that have both catalytic activity of high-carbon alcohol hydrodeoxygenation activity and carbon chain skeleton retention ability.The 2%Co-Mo₂C catalyst was screened out by modifying and adjusting the amount of doping with noble metal doping and transition metal doping.When 2%Co-Mo₂C catalyst was adopted to catalyze the hydrodeoxygenation of 2-ethyl-1-hexanol,the conversion rate reached 80.3%and the carbon chain skeleton retention rate reached 94.3%under the experimental conditions of240℃,4 MPa H₂,GHSV=2400h^-1,LHSV=0.8h^-1.These results indicated that the Mo₂C catalyst has sufficient hydrodeoxygenation activity and a certain degree of carbon skeleton rearrangement.The introduction of Co enhanced the hydrogenation ability of Mo2C,and also inhibited the rearrangement of the carbon chain skeleton,and retained the original branched carbon skeleton of higher alcohols during the hydrodeoxygenation process.2.The effect of space velocity on the hydrodeoxygenation reaction and the effect of 2%Co-Mo₂C catalyst on the catalytic performance of higher alcohol mono-and multi-component mixed feeds with different molecular configurations were investigated,and the results were obtained by kilogram ethanol Coupling,product separation,and high-carbon alcohol hydrodeoxygenation cascade experiments verify the feasibility of the technical route for preparing aviation bio-fuel from higher alcohols derived from ethanol coupling.The conversion rate and carbon chain skeleton retention rate were above 94%and 87%,respectively.When the branched chain of the feedstocks was atα/βposition,single/multi-branched,primary/secondary alcohol,the conversion rate of kilogram ethanol coupling was52.5%,the hydrodeoxygenation efficiency was 83.6%,the hydrocarbon yield within the carbon number range of aviation fuel was 56.7%.