MgO/Carbon nanocomposites synthesized in molten salts for catalytic isomerization of glucose to fructose in aqueous media

Isomerization of glucose into fructose has always been an important step in the biorefining process.This study synthesized a novel Mg-decorated carbonaceous catalyst by molten salt method for the application of glucose isomerization.The morphology of carbon microspheres was formed with high specific surface area and pore volume.The effects of Mg loading,catalyst dosage,reaction temperature,and reaction time were investigated and optimized.The highest fructose yield of 34.58%and fructose selectivity of 81.17%were achieved by the catalyst named Mg(100mg)/Carbon at hydrothermal temperature of 100℃ with reaction time of 1.5-2 h,showing the superiority of the catalyst.The results of recycling tests indicated Mg(100mg)/Carbon has good recyclability and can restore its activity after a simple regeneration.And the possible mechanism of glucose isomerization by Mg(100mg)/Carbon was indicated.This study provided a new method for overcoming the difficulty of high energy barrier required for glucose isomerization in the biorefining process.

Effect of Different Ionic Liquids on 5-Hydroxymethylfurfural Preparation from Glucose in DMA over AlCl_(3):Experimental and Theoretical Study

In this work,effect of different ionic liquids(ILs)on 5-hydroxymethylfurfural(HMF)preparation from glucose in N,N-dimethylacetamide(DMA)over AlCl3 was revealed by a combined experimental and computational study.ILs used as cocatalysts in this work included N-methyl-2-pyrrolidone hydrogen sulfate([NMP]HSO_(4)),N-methyl-2-pyrrolidone methyl sulfate([NMP]CH_(3)SO_(3)),N-methyl-2-pyrrolidone chlorine([NMP]Cl)and N-methyl-2-pyrrolidone bromide([NMP]Br)which were endowed with the same cation but different anions.According to the conclusion that fructose was intermediate product from glucose to HMF,we found fructose was transformed to more by-products by[NMP]H_(S)O_(4),making HMF yield decline significantly when glucose was treated as substrate.Neither glucose nor fructose could be converted by[NMP]CH_(3)SO_(3)efficiently,leading to its no influence on glucose conversion to HMF.[NMP]Br had a higher selectivity for HMF from fructose than[NMP]Cl and AlCl3.Besides,Al^(3+)preferred to combine with Br−,slightly decreasing both the overall free energy barrier for glucose isomerization and activation barrier for H-shift at 393.15 K.So a high HMF yield of 57%was obtained from glucose catalyzed by AlCl3 together with[NMP]Br under mild conditions.