The Study On Transformation Of Biomass-Derived Furan Aldehydes Catalyzed By Transition Metals-Based Nanoparticles

To improve the current energy demand,and conform to the trend of the enconomy development and implement the strategy of sustainable production,biomass energy conversion technology has attracted extensive research interest.As one of the most important biomass-derived platform compounds,biomass-derived furanic aldehydes can undergo such organic reactions as the hydrogenation,reductive amination,oxidation,esterification,condensation,decarbonylation,etherification,nitration,oxidative condensation to synthesize high value-added chemical products and pharmaceutical intermediates,which has remarkable economic and social benefits.Therefore,it is of great scientific significance and research value to study the catalytic transformation of biomass-derived furfural and its derivates.In this thesis,the oxidative condensation and hydrogenation of furfural in aliphatic alcohols were studied in order to produce longer hydrocarbon chains of low volatile liquid fuel and its precursors,starting from common transition metals such as iron,palladium.In addition,the selective oxidation of 5-hydroxymethylfurfural（HMF）to 2,5-dimethylfuran（DFF）over manganese-based catalysts was systematically investigated.The researches provide a promising efficient,environment-friendly,economical and recyclable catalytic route for the upgrading and utilization of renewable biomass-derived platform furan compounds.The research mainly covers the following three parts:（1）A kind of Fe@C heterogeneous catalyst with high activity and good chemical selectivity was prepared by a simple coordination reduction method,in which the non-noble iron nanoparticles were reduced and in-situ loaded in molecular carbon framework of organic complexes.The catalysts are compatible for oxidation condensation reaction of furfural with aliphatic alcohol and furfural hydrogenation,which showed that the conversion of furfural could reach about 84.2%and the selectivity of main product 3-（2-furyl）-acrolein could arrive at 82.7%in“furfural-ethanol-O₂（FEO）”system;on the other hand,the conversion of furfural and the yield of main product furfural alcohol was respectively 100%and 95%in“furfural-ethanol-hydrogen（FEH）”system.In the following process,the suitable preparation conditions of catalysts was selected through optimizing the synthesis process of catalyst,and a series of characterizations were performed for the catalysts or precursors at specific stages,including powder X-ray diffraction（XRD）,Fourier transform infrared（FT-IR）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,high resolution transmission electron microscopy（HRTEM）,X-ray photoelectron spectroscopy（XPS）,inductively coupled plasma atomic emission spectrometry（ICP-OES）,physical adsorption and desorption（BET）,chemical adsorption and desorption（NH₃-TPD）,thermogravimetric analyzer（TGA）,etc.The microcosmic morphologies structures,physical and chemical peroperties of catalyst were explored in detail.The relationship between the physical and chemical properties of the catalyst and its catalytic performance was systematically clarified.Finally,the good stability and excellent cycle performance of the catalyst were studied and proved.（2）The atomically Pd@TiO₂ catalyst was prepared by a photochemical reduction method,where the mono-dispersed PdO@TiO₂ catalyst was gained after calcination.The oxidative condensation of furfural and aliphatic alcohol to 2-methyl-3-（2-furyl）-acrolein was achieved with PdO@TiO₂ as the catalyst under suitable conditions.The results showed that the conversion of furfural could reach 77.9%,and the selectivity of target product2-methyl-3-（2-furyl）-acrolein reached 89.9%.Therein,the catalyst showed excellent stability.After that,the catalysts were tested and characterized by different instruments,such as XRD,FT-IR,SEM,TEM,HRTEM,XPS,UV-vis,ICP-OES,BET,NH₃-TPD,CO₂-TPD,TGA,etc.Based on the physical and chemical properties of catalysts,reaction phenomena and data of control experiments,a possible catalytic mechanism has been proposed for the selective conversion of furfural with palladium oxide catalyst.（3）A series of manganese-based nanomaterials were prepared by the deposition-precipitation method.The selective oxidation of HMF to DFF was succefully performed.The results showed that the alkali metal（e.g.Li,Na,K,Cs）and manganese mixed oxides exhibited superior catalytic performances to other manganese-based oxides.Under appropriate reaction conditions,the conversion of HMF and the yield of DFF was respectively95%and over 90%with Li-birnessite catalyst.The properties including the morphology and structural characteristics of these catalysts were further characterized by XRD,FT-IR,SEM,XPS,ICP-OES,BET,NH₃-TPD,CO₂-TPD and TGA techniques,respectively.The relationship between the physical and chemical properties of the catalysts and their catalytic performance was systematically discussed.Moreover,the stability of the catalyst was also investigated,and its prominent recyclablity exhibits a wide application prospect.Finally,a possible catalytic mechanism for the selective oxidation process was proposed according to reaction phenomena,catalyst structures and the control experiment results.