Research On Selective Oxidative Condensation Of Biomass-derived Furfural With Straight Chain C₃-C₆ Alcohols In The Presence Of Oxygen

As fossil resources continue to be depleted and there is an increasing focus on environmental climate issues,the search for renewable resources that can be converted into the value-added chemicals and high quality fuels is gaining traction among scientists.Among these,the development and efficient unitization of furfural,an industrially large scale produced biomass-based platform compound,can promote the achievement of the low-carbon economy and the“dual carbon”goal.Therefore,the research on the selective oxidative condensation of furfural with the aliphatic alcohol is of great scientific significance and application prospect.In this thesis,the promotion effect of different copper-based catalysts on the oxidation-condensation reaction of furfural with straight chain alcohols was investigated.Firstly,the homogeneous catalytic system consisting of cuprous chloride and lithium hydroxide was employed for the efficient oxidation-condensation reaction of the furfural with n-propanol,and by optimizing the conditions such as catalyst amount,basic additives,solvents and temperature,and so on,it was found that the conversion of furfural could reach 94%at 60°C for 2 h under 0.3 MPa O₂,and the selectivity of the main product 3-（2-furyl）-2-methylacrolein kept more than 99%.Finally,based on the reaction phenomena and control experimental data,a reasonable catalytic reaction mechanism has also been proposed.Next,the oxidative conversion of biomass-derived furfural with n-butanol was investigated in detail.The catalytic performance of different metal oxides such as the Fe₂O₃,Fe O,Co₂O₃,Co O,Mn O₂,Mn O,Cu O and Cu₂O on the conversion of furfural was investigated,and the effects of different straight-chain alcohols,reaction time and reaction temperature on the oxidation condensation were examined.The results showed that the conversion of furfural and the selectivity of the target product2-（2-furanylmethylene）-butyraldehyde arrived at 97.1%and 95.4%,respectively,with Cu₂O and Li OH as the catalyst at 60℃ after 4 h.The relationship between the activity and microscopic properties of the catalyst,such as crystalline structure,specific surface area and pore volume,size and size,were then systematically summarized relied on the XRD,BET,FT-IR and SEM characterization results.Therein,it is found that the synergy of the Cu₂O and Li OH should be responsible to impel the oxidation-condensation reactions.Finally,the effect of the copper supported catalyst on the oxidation-condensation reaction of furfural with n-pentyl alcohol was investigated.A series of copper supported catalysts were prepared by liquid-phase precipitation,and the low valance copper-based catalysts Cu/Fe₂O₃-1H,Cu/La₂O₃-1H,Cu/Ce O₂-1H,Cu/Co₂O₃-1H,Cu/Al₂O₃-1H and Cu/Zr O₂-1H were obtained by hydrogen reduction treatment.Through the valuation experiments,a 90.5%conversion of furfural and 93.9%selectivity of the main product 2-furan-2-methyleneglutaraldehyde was acquired using Cu/Fe₂O₃-1H as the catalyst at 80℃ for 2 h under 0.3 MPa O₂.The effects of different basic additives and the Li OH dosages on the oxidation-condensation reaction of furfural with n-pentyl alcohol were investigated in detail.Finally,the XRD and SEM characterisations of Cu/Fe₂O₃-1H were carried out to explain the promotion of the oxidation-condensation reaction of furfural by the low-valent copper.