Conversion of glucose to hydrogen-rich gas by supercritical water in a microchannel reactor

Microchannel reactors offer the intensification of heat transfer to endothermic chemical reactions. Microchannel reactors consist of a parallel array of micron-scale channels that are integrated into one device using microfabrication techniques. The gasification of glucose by supercritical water was studied in a stainless-steel microchannel reactor at 250 bar and 650-750 degrees C. The microchannel reactor architecture consisted of a parallel array of 21 rectangular microchannels (75 mu m x 500 mu m), each of 100 cm length, that were packaged into a serpentine pattern of 25 layers. At 750 degrees C, glucose was completely converted to eras products within a 2.0 s residence time, yielding an average gas composition of 53% H-2, 35% CO2, 10% CH4, and 0.5% CO and a H-2 yield of 5.7 +/- 0.3 mol H-2/mol glucose. At 650 degrees C, the intermediate products from the decomposition of glucose prior to their gasification and reforming were characterized. Routes for glucose transformation included the decomposition to acetic and propanoic acids, acid-catalyzed dehydration to 5-hydroxymethyl-furfural and 2,5-hexanedione, and conversion to phenol. This study has shown that microchannel reactors have considerable promise for intensifying the thermochemical conversion of biomass constituents to useful chemicals and fuels.