Research On A Catalytic Oxidative Condensation Of Bio-based Platform Compound Furfural And Ethanolin The Presence Of Molecular Oxygen

At present,with the excessive consumption of fossil fuel and serious environmental pollution,the development of renewable energy has become a very urgent and important research orientation.As a sustainable resource,biomass feedstocks have numerous potential merits,such as low pollution and widespread distribution.Therefore,it is of great significance to explore the efficient catalytic conversion of biomass and its derivatives to valuable chemicals and liquid fuel.As a kind of important bio-based platform compound,furfural can be converted into many value-added products and high quality fuels by oxidation condensation,oxidation esterification,hydrogenation reduction and reductive amine and other catalytic processes.Therefore,it is very promising and important to perform the catalytic tandem oxidative condensation of renewable furfural with ethanol in the science and industrial applications.In this paper,the catalytic transformation of furfural by the homogeneous copper catalyst and the heterogeneous nano gold solid catalyst in the presence of dioxygen.In homogeneous catalyst system,the combination of copper salt and azodicarboxylate was employed in the oxidative condensation as.Firstly,the hydrogen transfer process between furfural and ethanol is studied with the promotion of azodicarboxylate and alkali carbonates,in which both furfuryl alcohol and furan-2-acrolein are obtained as the main products.Next,to improve the yield of target product furan-2-acrolein,cuprous halides and ligand were added,wheremost of furfuryl alcohol could be further oxidized with molecular oxygen.As a result,it is found that the selectivity of furan-2-acrolein was significantly elevated when the CuI and o-phenanthroline were employed.Moreover,the conditions including the amount of copper,potassium carbonate,azodicarboxylate,reaction time and temperature were investigated and optimized.Under the suitable conditions,95.5%conversion of furfural with 81.5%selectivity of furan-2-acrolein is achieved at 160oC for 24 h under 0.3 MPa of O₂.Finally,based on the experimental phenomena and experimental results,a possible reaction mechanism is proposed.In heterogenous catalyst system,the supported gold nanoparticle and basic additives were employed in the catalytic reaction.Firstly,thesupported gold nano particles were prepared by deposition precipitation technique,and the activities of produced Au/FH?Au/H?Au/CeO₂and Au/Fe₃O₄ were studied in detail.Particularly,the solid base CaO was chosen as the additive to make whole process is easily recycled.The experimental results showed that when Au/FH was used as catalyst 64.8%conversion of furfural in 67.4%selectivity of furan-2-acrolein is achieved in 15 mL of ethanol at 140oC for 4 h.Furthermore,the influences of different reaction temperature,time and the amount of catalyst were studied for the oxidative condensation of furfural and ethanolreaction.Finally,the microstructure of the catalyst,such as crystal structure,ratio of surface area and pore volume,size and strength of the acid level,were analyzed by the XRD,BET,TEM and NH₃-TPD methods,and the correlation between the catalytic performance and catalyst structure is also discussed and summarized.