Moessbauer investigations of iron containing catalysts used for hydrogenation of brown coal at high pressure

The changes of the composition of added iron compounds are investigated in catalytic brown coal hydrogenation at high pressure by Moessbauer spectroscopy. The liquid yields are enhanced in dependence on both the vacancy content of the obtained pyrrhotite (FexS) and the dispersity of the active component. Iron compounds on carrier material are shown to be more efficient in the hydrogenation process than directly imposed iron sulfate due to pyrrhotite with lower iron content and the high dispersity of the active iron phase. Moessbauer spectroscopy is proved to represent a sensitive analytical method to characterize changes of iron containing phases in the course of hydrogenation process. (author)