Catalytic activities and morphology of iron-sulfur catalysts in the coal liquefaction

摘要

Iron carbonyl-sulfur complexes such as [Fe(CO)_3S]_2, [CH_3SFe(CO)_3]_2, and [t-BuSFe(CO)_3]_2 were prepared, and tested as catalyst precursors for coal liquefaction. They afforded slightly higher coal conversions (ca. 90 %) and oil yields (ca. 52 %) than Fe(CO)_5-S, at S/Fe ratio of 2. The iron-sulfur catalysts were heat-treated at 175 -420°C without coal, and then subjected to XRD and XPS analyses. Pyrrhotite (Fe_(1-x)S) was the major phase at above 200°C. However, week diffraction peek of pyrite (FeS_2) was observed in the sample prepared at 175 - 250°C. This seems to indicate that active species Fe_(1-x)S would be transformed from iron species through FeS_2 as an intermediate. Reaction of sulfur or H_2S with various iron sources such as Fe_2O_3, FeOOH, and Fe(CO)_5 were investigated at different temperatures in order to understand the transformation mechanisms of iron sulfides to pyrrhotite.