Microreactors for syngas conversion to higher alkanes: Characterization of sol-gel-encapsulated nanoscale Fe-Co catalysts in the microchannels

Silicon microreactors have been coated with mixed-metal Fe-Co Fischer-Tropsch catalysts in alumina sol-gel for conversion of syngas (CO + H-2) to higher alkanes. Characterization of the nanocatalysts using scanning electron microscopy, energy-dispersive X-ray, atomic force microscopy, and Brunauer-Emmett-Teller surface area measurements, packaging, and the reaction results from a mass spectrometer at controlled temperatures (200-260 degrees C) and pressure (1 atm) with varying H2:CO ratios from 1:1 to 10:1 are described. The catalyst does not adequately infiltrate the 5-mu m channels; it coats nicely the 25-mu m channels. The initial results are consistent with a lower conversion of CO (similar to 32%) in a 5-mu m-channel reactor and a higher conversion (similar to 52%) in a 25-mu m-channel reactor. The selectivity to propane (similar to 80%) is not affected by the width of the microchannels. The activity of the sol-gel-encapsulated catalyst before and after the reactions is estimated from its magnetic properties using a vibrating sample magnetometer.