Catalytic Conversion Of Glucose To 5-hydroxymethylfurfural Over B₂O₃ Solid Acid Catalysts

As the decreasing in nonrenewable fossil reserves,energy crisis has become a main challenge of the development of humanity.Biomass as an abundant,renewable,non-pollution and relative low cost novel energy sources has been recognized as a promising alternatives.5-Hydroxymethylfurfural(5-HMF),which is dehydrated production of glucose,has been identified as one of most crucial fine chemicals and can be used as versatile precursor in the synthesis of plastics,pharmaceuticals and liquid fuels.Therefore,searching for suitable catalytic system is particularly essential for transformation of glucose to 5-HMF.Several catalytic systems have been used for dehydration of glucose to 5-HMF.However,they are corrosive,expensive to separate from the system and pose environmental concern.The newer and greener methods have attracted much attention.Among of those,heterogeneous solid acids catalysts play a significant role in catalysts,because they can reduce corrosion to equipment,environmentally benign and easy to be recycling.Herein,we synthesized solid acid catalysts with binary metal oxide supported B2O3,the catalysts were used for conversion of glucose to 5-HMF in DMSO solvent to evaluate the catalytic performance.1.A series of supported B2O3/ZrO2-Al2O3 catalysts with different loading B2O3 were prepared by precipitation and impregnation method.These catalysts were applied for direct conversion of glucose to 5-hydroxymethylfurfural.The structure of B2O3/ZrO2-Al2O3 were characterized by X-ray powder diffraction(XRD)and FT-IR,and the chemical state of the elements in catalyst were recorded by the X-ray photoelectron spectroscopy(XPS),and the acid strength and density of the catalyst were determined by NH3-TPD measurement,as well the nature of acid sites in the catalyst were analyzed by FT-IR(pyridine adsorption).The effects of various experimental parameters,such as B2O3 loading,reaction time and reaction temperature,Zr/Al molar ratio,glucose dosage,catalyst amount,reaction medium have been explored in order to attain an optimized reaction conditions for production of 5-HMF.The results show that an optimized 5-HMF yield of 41.2%was obtained within 4 h at 150 ? over BZA-0.20.The best catalytic performance of BZA-0.20 was associated with the highest amount of total acid(436 ?mol/g).The simultaneously bearing Lewis acid and Br(?)nsted acid sites were more efficient for production of 5-HMF from glucose.2.A series of B2O3/TiO2-Al2O3 solid acid catalysts with different B2O3 loading were synthesized.The structure of B2O3/TiO2-Al2O3 were characterized by XRD and FT-IR,and the chemical state of the elements in catalyst were recorded by XPS,and the acid strength and density of the catalyst were determined by NH3-TPD measurement,as well the nature of acid sites in the catalyst were analyzed by FT-IR(pyridine adsorption).The activities were evaluated by conversion of glucose to 5-HMF.The yield of 5-HMF was achieved 47.3%under optimized reaction condition,which are 3 ml DMSO,50 mg glucose,20 mg BTA-0.20,150 ?,3 h.The best catalytic activity of BTA-0.20 was attributed to the highest amount of medium strong acid.The bearing of both Lewis and Br(?)nsted acid sites was found to be efficient for glucose-to-HMF conversion.