Lignocellulosic biomass is an attractive resource for producing transportation fuels, and consequently novel approaches are being sought for transforming the lignin and cellulosic constituents of biomass to fuels or fuel additives. Glucose, the monomer of cellulose, is a good starting material for exploring such chemistries. We report here the results of an investigation aimed at identifying catalysts for the dehydration of glucose to 5-hydroxymethylfurfural (HMF) dissolved in ionic liquids and the subsequent conversion of HMF to 2,5-dimethylfuran (DMF), a high-energy content product that could be used as a fuel or fuel additive. Heteropoly acids were found to be exceptionally active and selective catalysts for the dehydration of glucose. Nearly 100% yield of HMF could be achieved using 12-molybdophosphoric acid (12-MPA) in a solution of 1-ethyl-3-methylimidazolium chloride (EMIMCl) and acetonitrile. The addition of acetonitrile to EMIMCl suppressed the formation of humins from glucose. The high HMF selectivity achievable with heteropoly acid catalysts is ascribed to stabilization of 1,2-enediol and other intermediates involved in the dehydration of glucose and the avoidance of forming the 2,3-enediol intermediate leading to furylhydroxymethyl ketone (FHMK). Carbon-supported metals, and in particular Pd/C, were effective in promoting the hydrogenation of HMF dissolved in EMIMCl and acetonitrile to DMF. The following intermediates were observed in the hydrogenation of HMF to DMF: 5-methylfurfural (MF), 5-methylfurfyl alcohol (MFA), and 2,5-dihydroxymethylfuran (DHMF). The relative rate of formation and consumption of these compounds was explored by using each of them as a reactant in order to identify the reaction pathway from HMF to DMF. It was also observed that HMF produced via glucose dehydration could be converted to DMF without isolation, if the dehydration catalyst, 12 MPA, was replaced by the hydrogenation catalyst, Pd/C. This two-step catalytic approach provides the basis for completely converting glucose to HMF and further converting HMF to DMF.

A recently improved ionic liquid force field was used to compute the viscosity for binary and ternary mixtures of 1-ethyl-3-methylimidazolium chloride ([emim][Cl]) with water, acetonitrile, and glucose. For the same systems, experimental viscosity data are provided. The simulation and experimental results were in reasonable agreement. Simulations consistently overestimate the viscosities for the mixtures of [emim][Cl] and glucose while the viscosities of the mixtures of glucose and water are well reproduced. Both experiments and simulations show that the addition of acetonitrile reduces the viscosity of a solution of [emim][Cl] and glucose by more than an order of magnitude.

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