Sulfiding behavior of iron based coal liquefaction catalyst

In order to understand the transformation mechanisms of iron–sulfur catalyst systems to pyrrhotite, the iron catalysts (γ-FeOOH, α-FeOOH, Fe(CO)5 and Fe3(CO)12) and sulfur compounds (S and H2S) were heat-treated at 150–420°C with or without an activated carbon, and then subjected to XRD and XPS analyses. Pyrrhotite (Fe1−xS) was the major phase above 200°C in the XRD profiles of all iron–sulfur catalyst systems. However, the formation of pyrite (FeS2) from γ-FeOOH and γ-FeOOH on the catalyst surface was observed at 150–325°C by XPS analyses. This result seems to indicate that active species (Fe1−xS) would be transformed through FeS2 as an intermediate, but iron carbonyl complexes were directly transformed into pyrrhotite without the formation of FeS2.