(599b) Meso-Scale Studies of Simultaneous-Isomerization-Reactive-Extraction of Glucose to Fructose in a Flow Reactor

Glucose, a lignocellulose-derived sugar, can be converted into liquid fuels - ethanol by fermentation and other hydrocarbons by thermocatalytic conversion. In many biochemical and thermochemical processes, the yield and specificity of the reactions is much higher with fructose, the keto-isomer of glucose. However, the isomerization of glucose to fructose is equilibrium limited and does not favor fructose formation. The inability to fully utilize glucose or isomerize glucose to fructose limits the overall efficiency of the downstream chemistries and the economics of the products. We previously reported a bench-scale process - simultaneous-isomerization-and-reactive-extraction (SIRE), developed to shift the equilibrium isomerization to higher levels of fructose. Herein, we present results from experiments in a 2 L meso-scale flow set-up with mass transfer analysis of the SIRE processes to provide metrics for further scale-up. To characterize the SIRE process in the meso-scale flow set-up, isomerization and reactive-extraction were first decoupled and analyzed as stand-alone processes using a packed bed reactor and hollow fiber membrane contactor (HFMC), respectively. The sugar isomerization and extraction kinetics were compared with those from bench-scale shake-flask experiments. The packed bed reactor and HFMC module were integrated and operated together to implement the simultaneous-isomerization-and-reactive-extraction process for fructose production. A theoretical mass balance/mass transfer model of the reactive-extraction process was developed and predictions were in good agreement with the experimentally measured sugar concentration profiles. Diffusion of through the hydrophobic membrane in the extraction module was found to be the rate-limiting step for the process. Alternative contacting methods for extraction should be evaluated for the next level of scale-up.