Preparation Of 5 - Hydroxymethyl Furfural And Furfural By Catalytic Transformation Of Monosaccharides From Titanic Acid Nanostructures

Over the last century, fossil resources such as oil, coal and natural gas, as the main feedstock for energy and important chemicals, greatly promote the development of human society and the economy. However, the growth in energy demand, combined with diminishing reserves and the environmental problems caused by the use of fossil resources, require the development of new sustainable sources. Biomass as a renewable resource is the most attractive alternative feedstock for fuels and bulk chemicals. Biomass can be converted into 5-hydroxymethylfurfural(5-HMF) and furfural, which are highly valuable platforms to synthesize important chemicals, pharmaceutical intermediates and so on. Therefore, the study of 5-HMF and furfural dehydrated from glucose, fructose, and xylose is of great significance.Recently, exploring catalysts and solvents was mainly intended to improve the conversion efficiency of monosaccharide. Solid acid catalysts have a promising application in production of 5-HMF with advantages of reuse, easy separation and eco-friendliness. Titanic hydroxide as a catalyst having both Lewis and Br?nsted acid sites can improve the conversion efficiency. As we known, 5-HMF in aqueous phase was easily combined with water and reduces its yield.But DMSO as the solvent can surpress the formation of byproducts. [EMIM]Br itself was a catalyst, which can improve conversion efficiency. Therefore, we select titanic hydroxide as catalyst, DMSO and [EMIM]Br as solvents.Firstly, titanic hydroxide nanotubes, nanofibers and nanosheets were synthesized through the hydrothermal methods. In addition, the zirconium oxide, niobium oxide and tungsten oxide were loaded on titanic hydroxide nanotubes by the incipient-wetness impregnation method. The surface morphology and structures of titanic hydroxide nanomaterials as the heterogeneous catalysts were characterized by X-ray diffraction, field emission scanning electron microscopy and transmission electron microscopy. Finally, the catalysts were applied to the reaction of 5-HMF and furfural dehydrated from monosaccharide.To obtain the optimum conditions for glucose, fructose and xylose dehydration, variables for the dehydration process, such as reaction temperature, reaction time, catalyst types and solvents were studied during the reaction. We can draw conclusions from the experimentalresults:(1) the highest yields of 5-HMF or furfural dehydrated from glucose, fructose, and xylose were 24.3%, 79.5% and 35.6% respectively when dimethyl sulfoxide(DMSO) was used as solvent;(2) the conversion of glucose, fructose and xylose to 5-HMF or furfural reached the maximum yields: 36.3%, 85.9% and 29.2% in the 1-ethyl-3-methylimidazolium bromide([EMIM]Br), respectively.