Preparation Of A Bifunctional Solid Acid Catalyst And Its Use In The Conversion Of Sugars To 5-hydroxymethylfurfural (5-HMF)

As the fossil energy shortage, to seek the sustainable resources used for the preparation of fuels and chemicals has become one of the focus and hot spot of scientif ic research today. Biomass is considered to be one of the world's most abundant renewable resources, 5-HMF products is an important platform compound, it is considered a bridge that crosses from the petrochemical industry and biomass. Solid acid catalyst has a strong acidic active center, and has the ability of water resistance, strong stability, corrosion of equipment and recyclable, etc, and at the same time solid catalysts with Lewis and Bronsted acid have good catalytic efficiency for conversion of sugar(especially glucose) to HMF.This paper utilized large storage capacity, cheap, renewable sugar as raw material, the preparation of catalytic convert sugar and achieve is high yield of 5-HMF results as the goal, this paper carried out the following work:(1) B-Al solid acid catalyst was prepared by the method of template and ultrasonic system from aluminum isopropoxide and phenylboronic acid through an evaporation- induced self-assembly(EISA) process. The different proportion(B:Al=2:1, 3:2, 2:3, 1:1, 1:2)and temperature(400 oC?500 oC?600 oC?700 oC) of catalysts were screened and selected the optimal catalyst ratio(B:Al=3:2). The catalyst was characterizated by FTIR, XRD, SEM, TEM, NH3-TPD, FTIR(pyridineadsorption) techniques, which indicated the catalyst was successfully synthetized. The optimal catalyst was used to catalyze glucose conversion to 5-HMF. A variety of factors that affected reaction such as reaction time, reaction temperature, catalyst amount, solvents and substrate type were researched. The optimum reaction condition is drawn as follows: 50 mg glucose, 20 mg catalyst, 1.0 g DMSO, 140 oC, 120 min, 39.9% yield of 5-HMF was obtained. It was found that 5-HMF yield slightly decreased from 39.9% to 30.9% in four consecutive cycles.(2) Partially hydroxylated AlF3(denoted as AlF3) was synthesized by using a sol–gel method, and unambiguously characterized by FT-IR, XRD, NH3-TPD, SEM, TEM, N2 adsorption–desorption, and FTIR(pyridineadsorption) techniques. The resulting mesoporous material(AlF3) simultaneously bearing Lewis and Br?nsted acid sites was efficient for producing 5-hydroxymethylfurfural(HMF) from glucose, and an optimized HMF yield of 57.3% at a glucose conversion of 95.5% was obtained within 10 h at 140 oC. The effects of reaction temperature, time, catalyst amount, solvent and substrate type, and the amount of Br?nsted/Lewis acid sites on conversion of glucose to 5-HMF were also investigated. The existence of both Lewis and Br?nsted acid sites in AlF3 was found to play a key role in glucose-to-HMF conversion.(3) Heteropoly acid was synthesized and characterized by FT-IR, NH3-TPD, SEM techniques, which indicated the catalyst was successfully synthetized. The optimal catalyst was used to catalyze glucose conversion to 5-HMF and an optimized 5- HMF yield of 23.2% was obtained with in 4 h at 140 oC. The effects of reaction temperature, time, catalyst amount, solvent and substrate type on conversion of glucose to 5-HMF were also studied. It was found that 5-HMF yield slightly decreased from 23.2% to 19.2% in five consecutive cycles.