Using Sub/Supercritical CO₂ as “Phase Separation Switch” for the Efficient Production of 5-Hydroxymethylfurfural from Fructose in an Ionic Liquid/Organic Biphasic System

Abstract

The formation of a series of side products causes low yield and difficult separation in 5-hydroxymethylfurfural (HMF) preparation. To overcome these problems, a novel switchable biphasic reaction/separation coupling system is proposed for the efficient preparation of HMF from fructose. The miscible ionic liquid (IL)/organic solvent is adjusted to two phases with CO2 as the “phase separation switch”. Reactants and catalyst are mainly enriched in the IL phase and the produced HMF is continuously extracted into the organic solvent phase. This leads to 84% yield of HMF and the mass ratio of HMF in the organic solvent phase to the IL phase of 1.3:1 in a biphasic system. Comparing to several commonly used systems and a biphasic system, the switchable biphasic reaction/separation coupling system is more efficient for HMF preparation. On the basis of the results, a biphasic consecutive process for HMF preparation is also proposed, which is an effective production process through recycling of the inexpensive and abundantly available solvents and CO2. It is expected that such a system may provide more applications for efficient reactions and separations in ILs.

Rapid, High‐Yield Fructose Dehydration to 5‐Hydroxymethylfurfural in Mixtures of Water and the Noncoordinating Ionic Liquid [bmim][OTf]

“…Li 6 ], achieving less than 10 %y ield in 30 min. [41][42][43] Therefore, abetter compromise between reaction time, heating method, and catalyst loading still needs to be achieved. [35] At riphasic system based on water andt he hydrophobic ionic liquid [bmim][NTf 2 ] led to 81 %H MF yield in 24 hw ith av anadiump hosphate catalyst.…”

“…[39,40] Different approaches have been proposed for HMF recovery, such as the use of supercritical CO 2 or high-vacuum entrained distillation, but the feasibility of applying these techniques on al arge scale is doubtful on account of the high cost associated with handling CO 2 or high vacuum. [41][42][43] Therefore, abetter compromise between reaction time, heating method, and catalyst loading still needs to be achieved. Some researchers have focused on the oxidation of the HMF formed in the reaction media directly to 2,5 furandicarboxylic acid (FDCA), which can be separated by water addition, [44,45] but this reactionp rovedt ob en onselective.…”

A Multiphase Protocol for Selective Hydrogenation and Reductive Amination of Levulinic Acid with Integrated Catalyst Recovery

“…[7] Other MP systemsb ased on mutuallyinsoluble solvents have been applied to the acid-catalyzed dehydrationo fm ono-, di-, and polysaccharides in water/ DMSO solutions in the presence of hydrophobic organic solvents such as methyl isobutyl ketone (MIBK), 1-butanol, 2-butanol, 1-hexane, and others, acting as extractants of products, [8] and to the hydrolytic breakdown of dimethylfuranf or the synthesis of 2,5-hexanedione. [12] Examples have been described for the extraction of HMF obtained by the dehydration of sugars, [13] the recovery of carvacrol derived from the hydrogenation of carvone, [14] the purification of phenolics from the fractionation of lignocellulosic biomass, [15] and the recoveryo fc ellulose from [EMIm][DEP]/ DMF solutions ( [EMIm][DEP] = 1-ethyl-3-methylimidazolium diethyl phosphate). [10,11] Such systems weres uccessfully used to confine reacting substrates and catalysts in the IL phase, whereas the products were recovered by compressed CO 2 (Scheme 1).…”

“…[10,11] Such systems weres uccessfully used to confine reacting substrates and catalysts in the IL phase, whereas the products were recovered by compressed CO 2 (Scheme 1). [12] Examples have been described for the extraction of HMF obtained by the dehydration of sugars, [13] the recovery of carvacrol derived from the hydrogenation of carvone, [14] the purification of phenolics from the fractionation of lignocellulosic biomass, [15] and the recoveryo fc ellulose from [EMIm][DEP]/ DMF solutions ( [EMIm][DEP] = 1-ethyl-3-methylimidazolium diethyl phosphate). [16] At 60-150 8Ca nd 15-35 bar H 2 ,t wo model reactions of levulinic acid (LA), hydrogenation and reductive amination with cyclohexylamine, were explored in am ultiphases ystem composed of an aqueous solution of reactants, ah ydrocarbon, and commercial 5% Ru/C as ah eterogeneous catalyst.…”

Heterogeneous Nb-containing catalyst/N,N-dimethylacetamide–salt mixtures: novel and efficient catalytic systems for the dehydration of fructose

“…The dehydration of fructose could be conducted in various solvents systems, including traditional organic solvents, 40,41 water, 42 multiphase systems, 43,44 and ionic liquids. 45 Since alkylimidazolium chloride ionic liquids were found to be an efficient solvent for dehydration of carbohydrates into HMF, ionic liquids as the dehydration solvents have attracted dramatic attention.…”