Temperature-programmed oxidation of sulfided cobalt-molybdate/alumina catalysts

The temperature-programmed oxidation of sulfided cobalt-molybdate, molybdate, and cobalt catalysts was carried out in a thermogravimetric reactor equipped with a differential thermal analyzer and a fixed-bed reactor equipped with a mass spectrometer. Attempts were made to elucidate changes in chemical states of supported metals and in sulfur forms during oxidation using X-ray photoelectron spectroscopy (XPS) and extended X-ray adsorption fine structure (EXAFS). The thermodynamics of sulfide transformation into oxides and sulfates was investigated