(738c) Efficient Cellulose Hydrolysis in Acidified Molten Salt Hydrate Reaction Media

The hydrolysis of cellulose in molten salt hydrates (aqueous solutions of inorganic salts with water content equal or less than the amount needed to fully hydrate the cation) has been investigated. After screening several inorganic salts we identified that the acidified molten LiBr hydrate is a solvent in which cellulose hydrolysis can efficiently proceed under mild reaction conditions. In particular, almost quantitative yields to water soluble products have been obtained when cellulose was mixed in (0.05M H₂SO₄-H₂O)/LiBr =3.25 solution and heated at 85^oC for 30 mins. The effects of temperature, acid concentration and LiBr/cellulose molar ratio on hydrolysis kinetics were also examined. The effect of these parameters on hydrolysis rates and on product distribution will be discussed. Hydrolysis rates increase with increasing temperature (apparent activation energy ~100kJ/mol) and H₂SO₄ concentration. However, in order to minimize humin formation both of these parameters have to be kept within certain limits. The enhancement of hydrolysis rates has been attributed to the interaction of the molten salt hydrate with the cellulose chains that transforms the initially crystalline cellulose to amorphous due to a disruption of the intra- and inter-chain hydrogen bond network; and to an enhancement of the apparent acidity with the H₂SO₄ probably due to polarization by the strong electric field surrounding the cations. Finally, the technical challenges that need to be addressed for downstream utilization of the hydrolysate and for molten salt hydrate recycling will also be discussed