| With the rapid consumption of petroleum-based fuels and the massive emission of greenhouse gases such as CO2,it is urgent to build a resource-saving and environment-friendly modern industry.As a kind of renewable energy,biomass energy has many advantages,such as wide sources,abundant reserves,short renewable period and environmental friendliness.Furfural is an important chemical that can be directly converted from biomass.It is widely used in biofuel,furan chemical raw material,solvent,extractant and solid resin,etc.,and has attracted the attention of researchers at home and abroad.This article first introduces the research background of liquefaction of biomass,the furfural production present situation,and the research progress.The production of raw materials,production process and formation mechanism of furfural were reviewed from aspects of the solvent system and catalyst type system of furfural catalytic systems and it is illustrated that the oxalic acid as is a catalyst has a unique advantage.The effects of the catalyst type and dosage,the reaction temperature and reaction time on preparation of furfural were investigated using corn cob as the feedstock and water as the solvent by control of single factor variables.The results showed that the optimal reaction conditions were as follows:the amount of catalyst used accounts for 8%of the corn cob feedstock weight,reaction temperature is 180℃,reaction time is 2.5h.Under the optimum conditions,the liquefaction rate of corn cob is 43.01%,and the furfural yield is 11.16%.X-ray diffraction(XRD)and thermogravimetric analysis(TG)were carried out for the corn cob and the reaction residue under different reaction time.The results showed that the hemicellulose in the corncob had obviously degraded.Compared with hydrochloric acid and sulfuric acid catalysts,the price of oxalic acid is more expensive,and the recovery of oxalic acid catalyst from furfural residue has a higher economic value,so many catalyst recovery experiments were carried out.The catalyst recovery was studied on three aspects:the ratio of washing water to solid,washing times and washing time.The experimental results showed that the recovery of oxalic acid reached 80%when the water was 90℃ with a solid-liquid ratio of 0.67 by washing two times and stirring 10min for each time.After 5 times of reusing,the recovered oxalic acid still showed good catalytic effect.Then,in order to further treat the furfural residue after the reaction,NaHSO4 was used as catalyst to liquefy furfural residue deeply at a higher solid-liquid ratio.The experimental conditions were as follows:catalyst accounted for 6%of the weight of furfural residue,reaction temperature was 210℃ and reaction time was 3h.Under these conditions,the liquefaction rate of furfural residue reached 27.68%.The content of levulinic acid in the filtrate after reaction was measured by spectrophotometer,and the yield of levulinic acid was 1.04%.Finally,simulation the distillation separation process for furfural using the Aspen Plus software for a given annual output of 5000 t of furfural project was conducted.The main structure parameters and the product purity are as follows:actual tray number is 37 and feed stage is 22,the top effluent after condensing water reflux,furfural as product.The furfural recovery was 99.81%,furfural purity is 97.12%,bottom dilute acetic acid solution containing 1.96%acetic acid.Figure[32]table[12]reference[119]... |
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