Chromium and copper-doped magnetite catalysts for the high temperature shift reaction

Copper and chromium-doped magnetite was prepared to be used as catalysts, in the active phase, in the high temperature shift (HTS) reaction. Samples were produced by heating a mixed hydrate ferric oxyhydroxide (IHA) in the range of 150-400 degrees C and characterized by means of chemical analysis, X-ray diffraction, thermal analysis (DSC and TG), infrared spectroscopy, surface area measurements, scanning electron microscopy and X-ray microanalysis. It was found that copper favors magnetite formation but does not affect significantly the crystallinity of the solids. Both chromium and copper improve the performance of the catalysts towards the HTS reaction: chromium acts as a stabilizer whereas copper increases the intrinsic activity. However, copper favors sinterization leading to solids with low surface areas. The increase in the catalytic activity and in the surface area of the solids reflects the synergy of these dopants.