In situ impregnated iron-based catalysts for direct coal liquefaction

Recent Advances in Direct Coal Liquefaction

“…It was widely recognized that a highly dispersed catalyst can be superior to a supported catalyst, because the dispersed catalyst has an intimate contact with the surface of coal particles, which facilitates the activation and transfer of hydrogen to the coal-derived fragments and reactive sites. Accordingly, finer particles and a higher dispersion of the catalyst species would lead to a higher catalytic activity [57][58][59][60]. Liu et al [58] tested DCL with an in situ impregnated iron-sulfide catalyst, where the coal was mixed with Na 2 S solution, followed by the addition of FeCl 3 solution, washing, filtration and drying.…”

“…Accordingly, finer particles and a higher dispersion of the catalyst species would lead to a higher catalytic activity [57][58][59][60]. Liu et al [58] tested DCL with an in situ impregnated iron-sulfide catalyst, where the coal was mixed with Na 2 S solution, followed by the addition of FeCl 3 solution, washing, filtration and drying. This highly dispersed catalyst even of a low loadings (<0.5 wt%) resulted in a high level of coal conversion.…”

Roles of Na 2 CO 3 in lignite hydroliquefaction with Fe-based catalyst

“…Moreover, Fe-based catalyst is well-known to be the most practical catalyst for coal hydroliquefaction, because of its relatively high activity, low cost and environmental benign for disposal [5][6][7][8][9][10][11][12][13][14][15][16][17]. Consequently, plenty of studies on coal hydroliquefaction mainly focused on these investigations for Fe-based catalyst: how to improve its catalytic activity by modifying its physical and chemical structures such as crystalline size [6], pore structure [18], dispersive degree [19,20], Fe precursor phase [21], Fe active phase [22], and surface acidity and basicity [8,[23][24][25].…”

The Characterization of Coal Liquefaction Products Obtained under an Inert Atmosphere and Catalytic Conditions. Part II: Soluble Products

“…Studies of catalytically accomplished coal liquefaction are generally based on determination of appropriate catalysts (metal oxides, metal salts, metal sulphates) and accelerator materials soluble in water and oil (Karaca, 1998). Since the iron derivative catalysts do not have any economic and environmental problems, they are preferred and widely used (Gray, 1986;Guin et al, 1994;Ibrahim and Seehra, 1994;Liu et al, 1996;Sharma et al, 1996;Stohl and Diegert, 1994;Taghiei et al, 1994;Watanabe et al, 1984;Zhao et al, 1994;Zmierczak et al, 1994). Another method improved recently to maximize the light liquid product (oil) yield in coal liquefaction is the usage of Fe and Mo compounds as catalysts (Artok et al, 1992;Curtis and Pellegrino, 1989;Karaca, 1998;Karaca et al, 2001;Warzinski et al, 1996;Watanabe et al, 1996).…”

“…As mentioned, besides the effect of catalyst type on the efficiency of coal liquefaction and quality of the product, the catalyst usage method also has a significant effect. Two different catalyst usage methods are employed in direct coal liquefaction (Liu et al, 1996). These are physically mixing of the catalyst and catalyst impregnation.…”