Evaluation of a novel mixed pyrite/pyrrhotite catalyst for coal liquefaction

Stansberry, Peter G.; Wann, Jyi-Perng; Stewart, William R.; Yang, Jianli; Zondlo, John W.; Stiller, Alfred H.; Dadyburjor, Dady B.

doi:10.1016/0016-2361(93)90082-d

Cited by 20 publications

(11 citation statements)

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“…Being that Fe 2 S 3 is thermodynamically unstable phase, it easily converts to pyrite (FeS 2 ) and Fe 3 S 4 , (eq ) or pyrite, pyrrhotite (FeS x ), and sulfur (eq , where α, β, and γ are the relative molar amounts). …”

Section: Resultsmentioning

confidence: 99%

“…Being that Fe 2 S 3 is thermodynamically unstable phase, it easily converts to pyrite (FeS 2 ) 12 and Fe 3 S 4 22,32 (eq 3.2) or pyrite, pyrrhotite (FeS x ), and sulfur 33 However, a small amount of SO 2 ascribable to the iron reduction is also detected. Even if the two composites show the same first-sulfidation SRC value, the higher amount of water released by Fe_Hex_Hyd during the substitution reaction is justified by the retention of H 2 S at a slightly higher level than the threshold of 100 ppm, suggesting that, with respect to the Fe_Cub composite, a higher amount of active phase is available to react with H 2 S.…”

Section: ■ Methodsmentioning

confidence: 99%

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γ-Fe₂O₃-M41S Sorbents for H₂S Removal: Effect of Different Porous Structures and Silica Wall Thickness

et al. 2018

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In this work, the effect of the M41S support pore structure (hexagonal or cubic) and of the wall thickness of the silica mesochannels has been evaluated aimed at achieving more and more efficient and regenerable iron oxidebased sorbents for H 2 S removal at midtemperature. With this purpose, we set up a simple Pluronic-free synthetic strategy capable of producing silica supports with hexagonal (MCM-41) or cubic (MCM-48) pore structure with different wall thicknesses that have been used to fabricate the corresponding sorbents made up of iron oxide nanoparticles homogeneously dispersed into the mesochannels. The combined use of 57 Fe-Mossbauer Spectroscopy and DC magnetometry has allowed for ascertaining the presence of maghemite in the form of ultrasmall nanoparticles in both composites and gives new insights on the influence of the different silica matrices on the active phase features. The performances of the sorbents have been evaluated at midtemperature (300 °C) through three repeated sulfidation and regeneration cycles and then correlated to their microstructure and textural properties.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Methodsmentioning

confidence: 99%

γ-Fe₂O₃-M41S Sorbents for H₂S Removal: Effect of Different Porous Structures and Silica Wall Thickness

et al. 2018

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“…This catalyst is termed EA. Detailed discussion on the synthesis of these catalysts may be found in Stansberry et al (1993) and Stiller et al (1995).…”

Section: Methodsmentioning

confidence: 99%

“…Catalyst NF has equal amounts of PH and PY before reaction. The work of Stansberry et al (1993) indicated that this is a superior catalyst overall for coal liquefaction. Catalyst HF has an appreciably higher value of the ratio PH/PY.…”

Section: Ph/py (Molar Ratio) )mentioning

confidence: 99%

“…The relative amount of PH and PY, as well as the type of PH formed (i.e., the value of x), depends on the time, temperature, pressure, and vapor-phase composition of disproportionation. In our laboratory, we have prepared these catalysts in a variety of ways, including hydrothermal (Stansberry et al, 1993), in-situ disproportionation (Liu et al, 1996), aerosol (Stiller et al, 1995) and reverse-micelle (Chadha et al, 1996) techniques.…”

Section: Introductionmentioning

confidence: 99%

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Characterization and Activity of Ferric-Sulfide-Based Catalyst in Model Reactions of Direct Coal Liquefaction: Effect of Preparation Conditions

Chadha

Stinespring

Stiller

et al. 1997

Ind. Eng. Chem. Res.

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We have studied the activity of various ferric-sulfide-based catalysts in model hydrogenation and cracking reactions under conditions typical of direct coal liquefaction (DCL). The catalysts used were mixtures of FeS 2 (pyrite, PY) and nonstoichiometric FeS x (pyrrhotite, PH) obtained by high-temperature disproportionation of ferric sulfide in a nitrogen atmosphere or a hydrogen atmosphere. The structural changes in the catalyst were also examined, both before and after the model reactions. The cracking functionality of the catalysts was studied by using cumene, and the hydrocracking functionality was studied by using diphenylmethane. Phenanthrene was used as a model compound for hydrogenation and hydrogen shuttling. Phenanthrene hydrogenation was studied in the presence of H 2 (g), and hydrogen shuttling was studied when a hydrogen donor (tetralin) was present in the absence of H 2 (g). All the model reactions were performed under conditions typical of DCL: 400 °C and 1000 psig for 30 min. The surface and bulk of the catalysts were characterized by Auger electron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic absorption spectroscopy. The performance of the catalysts was found to vary with the type of reaction, the initial ratio of FeS x to FeS 2 (PH/ PY) found in the catalyst, and the catalyst age. Catalysts freshly prepared in a nitrogen atmosphere were most active for model hydrogenation and hydrocracking runs. Catalysts freshly prepared in hydrogen were most active in shuttling. In all cases, catalytic cracking was negligible. Aging was found to reduce the activity of the catalyst. After the exposure of the catalyst to H 2 (g) at 375 °C, the ratio PH/PY increased, but only limited changes in the PH/PY ratio were noted in a helium atmosphere. The surface uniformity of the catalyst was reduced after the catalyst reacted in H 2 (g) or He(g). A simple model was developed to explain these changes in the surface and bulk of the catalysts. The model incorporates the hydrogenation of PY to PH and the removal of elemental S to form H 2 S. The further interaction of H 2 S with the catalyst surface makes it nonuniform, with S-deficient and S-rich sites. In the absence of hydrogen, surface reconstruction involves elemental S (from the disproportionation of the ferric sulfide) interacting with PH to form PH with a larger value of x, or PY in the limit.

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Coal Conversion Processes Liquefaction

Dadyburjor

Liu

2003

Kirk-Othmer Encyclopedia of Chemical Technology

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Coal liquefaction incorporates both an increase in the H/C ratio and removal of heteroatoms (S, N, O) and inorganic oxides (ash). Successful industrial processes must incorporate both these steps along with the transport of solid‐ and slurry‐phase material in large‐scale processing. The H/C ratio can be increased using high temperatures and pressures and a solvent (generally process derived), or by a catalyst, or by heating rapidly in the absence of a solvent in hydrogen or an inert atmosphere. Sometimes there are advantages to processing coal simultaneously with other fossil fuels such as resids. Typically, such operations, termed coprocessing, result in improved removal of heteroatoms and ash. The use of solids and slurries has resulted in novel reactors and processing steps. Fuel production can be direct, from the coal itself, or indirect, from synthesis gas (CO and H 2 ) obtained by gasification of the coal. Synthesis gas, in particular, can be used to produce chemicals other than fuels. The production of these chemicals often can be used to make favorable the economics of fuel production from coal.

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Evaluation of a novel mixed pyrite/pyrrhotite catalyst for coal liquefaction

Cited by 20 publications

References 8 publications

γ-Fe₂O₃-M41S Sorbents for H₂S Removal: Effect of Different Porous Structures and Silica Wall Thickness

γ-Fe₂O₃-M41S Sorbents for H₂S Removal: Effect of Different Porous Structures and Silica Wall Thickness

Characterization and Activity of Ferric-Sulfide-Based Catalyst in Model Reactions of Direct Coal Liquefaction: Effect of Preparation Conditions

Coal Conversion Processes Liquefaction

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Evaluation of a novel mixed pyrite/pyrrhotite catalyst for coal liquefaction

Cited by 20 publications

References 8 publications

γ-Fe2O3-M41S Sorbents for H2S Removal: Effect of Different Porous Structures and Silica Wall Thickness

γ-Fe2O3-M41S Sorbents for H2S Removal: Effect of Different Porous Structures and Silica Wall Thickness

Characterization and Activity of Ferric-Sulfide-Based Catalyst in Model Reactions of Direct Coal Liquefaction: Effect of Preparation Conditions

Coal Conversion Processes Liquefaction

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Product

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About

γ-Fe₂O₃-M41S Sorbents for H₂S Removal: Effect of Different Porous Structures and Silica Wall Thickness

γ-Fe₂O₃-M41S Sorbents for H₂S Removal: Effect of Different Porous Structures and Silica Wall Thickness