Iron Sulfide Catalysis in Coal Liquefaction

Iron(II) Disulfides as Precursors of Highly Selective Catalysts for Hydrodeoxygenation of Dibenzyl Ether into Toluene

“…pyrite or marcasite) are well known to enhance the reactivity of coals towards liquefaction under elevated H 2 pressure (100-300 bar) at high temperatures (350-450 8C). [1,2] In addition, there are also a few reports to suggest that sulfided iron catalysts facilitate the liquefaction of technical lignins under high severity conditions. [3][4][5][6] Analyzing the key studies published over the last 50 years, one can easily identify two main classes of FeÀS catalysts that have been explored for coal and lignin liquefaction.…”

“…The first class comprises bulk iron(II) disulfides of low surface area (< 2 m 2 g À1 ), which have been almost exclusively applied to direct coal liquefaction. [1,2,6] The second class encompasses sulfided iron species formed in situ by reactions of an iron compound [e.g. ferrocene, Fe(NO 3 ) 3 ] and a sulfur source (e.g.…”

“…Indeed, most knowledge in this field originates from reports dated back to the 1980s. [2,7,8] More recently, some indepth computational studies of pyrite surface and structure were reported. [9][10][11][12][13][14][15] From a catalysis perspective, therefore, revisiting this research field with modern techniques for preparation and characterization of highly dispersed iron(II) disulfide phases on supports exhibiting high surface area could contribute insights as to whether these materials can be useful as cat-alysts or catalyst precursors in the conversion of biomass-derived aromatic streams.…”

“…chiometric iron(II) sulfides, called pyrrhotites (Fe (1Àx) S where 0 x 0.125). [2,8] Pyrrhotites possess a NiAs-type structure (Figure 1 c), which can exhibit monoclinic or hexagonal crystal symmetry. [17,19,20] One can describe the monoclinic pyrrhotite by subtracting one-eighth iron atoms from the hexagonal FeS structure, so that the resulting structure contains alternating layers of full Fe sites and layers of Fe sites with vacancies.…”

“…The role of each iron(II) sulfide and iron(II) disulfide in the coal or lignin liquefaction processes is only partially understood. [2,7,8] Although pyrrhotite (prepared in advance) shows a lower activity than pyrite in coal liquefaction, pyrrhotite formed in situ was demonstrated to possess 'very good' catalytic activity. [8] Kodaira et al surmised that the formation of the fresh surface with the chemical change from pyrite to pyrrhotite is the cause of the high activity of pyrite.…”