The selective production of glucose from the hydrolysis of cellulose is the key step for an efficient use of the lignocellulose biomass. Crystalline cellulose can be dissolved in molten salt hydrates (MSHs) and hydrolyzed to glucose with high selectivity. However, the separation of the glucose formed is difficult because of its high solubility in the MSHs. To address this issue, a step-by-step method is being introduced in which cellulose is hydrolyzed to short chain glucan oligomers in the LiBr MSH. We have shown that, compared to glucose, the formed glucan oligomers with a degree of polymerization of 4 to 11 can be efficiently separated from the MSH hydrolyzate using an anti-solvent precipitation process. The separated oligomers can easily be converted to glucose under mild conditions and used for other applications. Under optimized conditions, 90.3% glucan oligomer can be produced from crystalline cellulose and separated from the MSH by adding methanol, and the precipitated glucan oligomer can be hydrolyzed to glucose with a yield of 99.7% using dilute sulfuric acid. We show that the precipitation efficiency is influenced by the chain length of the glucan oligomer, the type of glycoside bond and the concentration. In addition, the separation of glucan oligomer from cotton straw hydrolyzate was investigated at the MSH. A 79.2% yield of glucan oligomer was obtained by hydrolyzing cotton straw at 130 ° C for 2 hours. With the addition of methanol, glucan oligomer was precipitated with a selectivity of 60.8%.


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