Comparative Studies of Silica-Encapsulated Iron, Cobalt, and Ruthenium Nanocatalysts for Fischer-Tropsch Synthesis in Silicon-Microchannel Microreactors

FischerTropsch (FT) synthesis in Si-microchannel microreactors, containing 116 channels (50 mu m x 100 mu m x 1.3 cm), was carried out using SiO2-encapsulated Fe, Co, and Ru catalysts. The microchannels were uniformly coated with catalyst via a modified closed channel infiltration (mCCI) procedure. The mCCI method helps to load the catalyst without blockage of channels with no issues related to anodic bonding. The catalysts were characterized by scanning electron microscopy, optical microscopy, energy-dispersive X-ray spectroscopy, and BrunaerEmmettTeller analysis. The metal type, temperature, and H-2/CO mole ratio showed a significant effect on FT synthesis. The highest FT reactivity of 0.1746 mol of CO g(1) h(1) was observed for Ru/SiO2, and the highest CO conversion of 90% was obtained with Co/SiO2 at 250 degrees C. The highest selectivity to propane (44%) and butane (8%) was observed for Co/SiO2 and Ru/SiO2, respectively, at 250 degrees C and 3:1 H-2/CO. The deactivation rates of the catalysts in the microreactor for FT synthesis followed the order Ru/SiO2 > Fe/SiO2 > Co/SiO2.