Treatments of Lignocellulosic Hydrolysates and Continuous-Flow Hydrogenation of Xylose to Xylitol

Xylitol is produced by the heterogeneous catalytic hydrogenation of xylose over Raney nickel. The hydrogenation must typically be followed by several purification steps, which makes the chemical production relatively complex and expensive. In this study, activated carbon and bio-purification treatments of corn stover hydrolysates and subsequent nickel-catalyzed hydrogenation of xylose to xylitol were investigated. The activated carbon treatment was used to eliminate inhibitory compounds and increase the efficiency of the bio-purification step. It was found that the glucose could be completely eliminated from the hydrolysate. The hydrogenation reactions of corn stover hydrolysate demonstrated that a high reaction temperature resulted in high sugar alcohol yields and selectivity. At a given temperature, the flow rate had no significant effect on xylitol yield.