Catalytic Dehydration Of Monosaccharide Into 5-hydroxymethylfurfural (HMF) In The Ionic Liquids

With the rapid consumption of non-renewable resources,the renewable biomass resources,in particular lignocellulosics biomass,has received more attention in producing chemicals.Lignocellulose may be converted to bulk chemicals by a hydrolysis reaction. During hydrolysis,the lignocellulose is cleaved to give monosaccharide,which can be decomposed further into useful chemicals.Results of most research showed that the first step(lignocellulose—monosaccharide)was a crucial step and had substantial impact on the selectivity and yield of chemical product.The traditional hydrolysis of biomass used liquid acid as catalysts such as hydrochloric acid and sulfuric acid,but the liquid acid had a negative impact on the reactor and on the global environment,Focusing on the conversion of biomass in ionic liquid,following study was did in this paper.In this thesis the dehydration of fructose to 5-hydroxymethylfurfural(5-HMF) catalyzed by the synergies of solid acid and ionic liquids was studied.The main problem of this reaction is the low selectivity and equipments erosion and environment pollution bringed in by catalysts.So choosing a catalyst with high selectivity is the key to solve the problems.This thesis studied the selective synthesis of fructose to 5-hydroxymethylfurfural(5-HMF) in the condition of imidazole ionic liquids as solvents and solid acid as catalysts.We studied the ionic liquid and molecular sieve system as well as ionic liquid and metal salts system.By investigating some factors such as reaction time,reaction temperature,solvent,we get the best reaction condition:fructose 100 mg,1-ethyl-3-methylimidazolium bromide as the solvent,the ratio of VOP and fructose 1:10,100℃,30 min,yield 73%;fructose 100 mg, 11-ethyl-3-methylimidazolium bromide as the solvent,the ratio of Hβzeolite and fructose 1:4, 80℃,60 min,yield 88.5%;dehydration of glucose into 5-hydroxymethylfurfural(5-HMF) over Hβzeolite which be loaded Cr³⁺ salts as catalyst was studied in ionic liquid,the 5-HMF yield can achieve 35%after 90 min under 110℃.