Iron sulphide containing hydrodesulfurization catalysts : Mössbauer study of the sulfidibility of alpha-iron(III) oxide

As a first step in the study of the sulphidation of carbon-supported iron oxide catalyst systems the sulphiding of a well-characterized, unsupported model compound, viz. a-Fe2O3(mean particle diameter ca. 50 nm) was investigated using in-situ Mössbauer spectroscopy and the temperature-programmed sulphiding technique. Sulphidation was carried out in a flow of 10% hydrogen sulphide in hydrogen. At room temperature and atmospheric pressure no bulk sulphidation of the a-Fe2O3particles was observed. However, as the sulphidation temperature increased a direct transformation of bulk a-Fe2O3into iron sulphides took place. The iron-to-sulphur ratio of the iron sulphides formed during the sulphidation process was initially 2 and decreased to 1 with increasing sulphidation time and/or temperature.