Levulinic Acid Production From Glucose By Aqueous Phase Catalysis

Levulinic acid can be used in many fields such as pharmaceutical intermediates,spice raw materials,coating additives,bio-based materials and synthetic biofuels,and presents a broad application prospects.Currently,levulinic acid is mainly obtained by hydrolyzing biomass resources,usually under ionic liquid and liquid acid catalytic systems,but some problems should be noted such as complicated treatment process,high equipment requirements,and difficult separation.The study of solid acid catalysts for biomass utilization has attracted much attentions.The reaction process is complex and involves intermediate steps such as hydrolysis,isomerization,dehydration and rearrangement,and there are still low availability of raw materials and difficulty in the production of levulinic acid on solid acid catalysts.?1?MgO/NaY solid base catalysts were prepared by impregnation method.The effect of catalyst preparation process on the catalyst structure and the basic sites was investigated.The key reaction parameters for glucose isomerization?e.g.,reaction temperature,reaction time,and glucose concentration?were investigated.The maximal fructose yield of 33.8%with the selectivity of 67.3%was achieved over the 10%MgO/NaY catalyst at 100°C for 2 h.?2?Natural attapulgite was selected as a solid base catalyst for glucose isomerization.The effect of the heat treatment of attapulgite on the structure and basic sites of the catalyst was investigated.Under the optimum reaction conditions for 2 h,the highest fructose yield of 20.6%was obtained with the selectivity of 77.9%over attapulgite calcined at 500°C.?3?Combing acidic molecular sieves with Lewis acid catalysts,the effects of the catalyst structure and acidic sites on the dehydration of fructose to levulinic acid were investigated.The results showed that the 5%B_RR2RRO_RR3RR/H?solid acid catalyst had good catalytic performance for the dehydration of fructose.The yield of levulinic acid was found to be 63.4%with a complete converison of frucotse after the reaction at 160°C for 3 h,which was better than that of the selected homogeneous Lewis acid catalyst.