Research On Synthesis Of Fuel Precursors And Furoic Acid From Biomass

Biomass is a renewable resource which can replace fossil energy for the preparation of biofuel and high value-added compounds.With the advantage of abundant reserves,biomass has received widespread attention in recent years.However,the structure of biomass is rather complex.Multiple process steps are typically involved to convert biomass feedstock to target products.The complex conversion process inevitably brings about some problems such as long reaction time,complicated processes and high energy consumption.Therefore,it is critical to develop an efficient and intensive conversion method for direct conversion of biomass to high valuable products.In this work,the biomass platform compound furfural(FF)was firstly used as the model feedstock to study the direct conversion technology with biomass.Firstly,the major influence factors of the conversion of FF to fuel precursors(C10,C15)under the condition of deep eutectic solvent(DES)were studied.Based on the obtained condition,one-pot conversion of xylose/corn cob into biofuel precursors was investigated to achieve its suitable reaction conditions.After reaction,the residue of the corncob was subjected to muffle furnace to produce biochar to realize the comprehensive utilization of raw biomass.Finally,the charcoal-derived biochar was used as a carrier to prepare a catalyst to catalyze the conversion of FF to furoic acid(FA)to achieve efficient use of resources.The main contents and results of this thesis are as follows:(1)FF and cyclopentanone(CPO)were used as raw materials.Six different DES systems were used to condensation reactions to produce fuel precursors C10 and C15.The DES system which has high biofuel precursors was selected as the reaction condition and the related mechanisms were also analyzed.The results indicated that DES reaction system that formed by formic acid and choline chloride(Fa/ChCl)performed the best catalytic effect on the production of fuel precursors.The conversion rate of furfural could reach 99.81%under the condition of 100℃ for 210 min.The optimum molar ratio of formic acid to choline chloride for the reaction was 12:1,an addition amount of catalyst SnCl4·5H2O was 0.002 mol,and a mass ratio of furfural to cyclopentanone was 1:6.The selectivity of C10 and C15 were 47.64%and 44.56%respectively with the total products yield of 92.03%.Moreover,the mechanisms were speculated that Sn(Ⅳ)ion and H+in DES of Fa/ChCl would together contribute to the catalysis of aldol condensation.Both H+and Sn(Ⅳ)acted on cyclopentanone which with carbonyl,to form C=C double bond enol structure,which then dehydrated with FF to form fuel precursors(C10 or C15).(2)Based on the above obtained reaction condition,xylose and corn cob were used to substitute FF to realize the direct condensation reaction with CPO.The effect of the loading of raw material and catalyzer,etc.on direct conversion of fuel precursors C10 and C15 was investigated.The results indicated that the total yield of fuel precursors reached 88.24%when the solid-liquid ratio of xylose to DES system was 0.02,and the amount of catalyst added was 0.003 mol.When corn cob was used as the raw material,the total yield of fuel precursors was 56.78%with 0.003 mol catalyzer.Furthermore,it was found that the hydrolysis rate of biomass and its dehydration rate to produce FF was higher when the biomass presented in high hemicellulose and low lignin content,under the action of the catalyzer.And the total yield of biofuel precursors produced by the condensation reaction with CPO was also higher.(3)The corn cob residue was subjected to slow pyrolysis process with high carbonization temperature from 300 to 500℃ to prepare biochar to achieved the goal of highly efficient residue utilization.Meanwhile,the physical and chemical characteristics of the produced biochar were analyzed using X-ray diffraction(XRD),scanning electron microscopy(SEM),thermogravimetry(TG)and elemental analysis.The results showed that the solid yield of the produced biochar gradually decreased as the reaction temperature rising.The degree of graphitization,the element ratio(C/H,C/O)gradually increased,and the surface structure gradually stabilized with the temperature increasing.Therefore,under the range of slow pyrolysis,the biochar produced at high temperature of 500℃was used in the subsequent experiment.(4)Biochar obtained from carbonization of corn cob residues was used as a carbon-based carrier.And different loadings of SnO2/C solid catalyzer were prepared by chemical deposition.The produced catalyzers were characterized via XRD,SEM and FTIR.Meanwhile,the synthesis of furoic acid(FA)from FF in the DES system formed by Fa and ChCl with these catalyzers were optimized.The results indicated that the catalyzers would be aggregate with increasing loading.When the loading of SnO2 was 55%,the optimum molar ratio of formic acid to choline chloride was 8:1 and the maximum yield of FA could reach 45.04%at 120℃ for 8 h.In this thesis,biomass was used as a raw material,and the process of its direct conversion into fuel precursor and furoic acid in the DES system was preliminary investigated.The work of this paper developed a new way for highly efficient conversion of biomass to biofuel and products.It also would provide theoretical support for the technology development of direct conversion of biomass.