A comparative FMR study of the reduction of Co-containing catalysts for the Fischer–Tropsch process in hydrogen and supercritical isopropanol

Resumo

An in situ comparative study of the reduction of Co-containing catalysts for the Fischer–Tropsch process in hydrogen and supercritical (SC) isopropanol is performed by ferromagnetic resonance (FMR) spectroscopy. According to the FMR data, the reduction of cobalt-containing oxide particles to metal in hydrogen starts at temperatures of ~360°C, which is substantially lower than a temperature of the formation of metal particles of the active phase according to powder X-ray diffraction and differential thermogravimetry data (Т ~ 450°C). In SC isopropanol, the reduction to Co metal occurs at lower temperatures (T ~ 245°C) as compared with the reduction temperature for these catalysts in hydrogen. It is shown that the reduction in SC isopropanol can lead to the formation of superparamagnetic Co nanoparticles with a narrow particle size distribution.