Active Species of Sulfated Metal Oxide Catalyst for Propane Dehydrogenation

Watanabe, Ryo; Hirata, Naru; Fukuhara, Choji

doi:10.1627/jpi.60.223

Cited by 9 publications

(10 citation statements)

References 24 publications

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“…Recently, Watanabe et al , investigated SiO 2 supported Fe, Ni, and Co for PDH in the presence of H 2 S. Their study showed that 20 Fe/SiO 2 after exposure to H 2 S could selectively activate propane. The authors proposed that Fe (1– x ) S was the active phase for the reaction based on XRD, XPS, and XAS techniques.…”

Section: Introductionmentioning

confidence: 99%

Sulfur Tolerant Subnanometer Fe/Alumina Catalysts for Propane Dehydrogenation

Sharma

Purdy

Page

et al. 2021

ACS Appl. Nano Mater.

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A series of Al 2 O 3 -supported Fe-containing catalysts were synthesized by incipient wetness impregnation. The iron surface density was varied from 1 to 13 Fe atoms/nm 2 spanning submonolayer to above-monolayer coverage. The resulting supported Fe-catalysts were characterized by N 2 physisorption, ex situ X-ray diffraction (XRD), X-ray pair distribution function (PDF), X-ray absorption spectroscopy (XAS), aberration corrected scanning transmission electron microscopy (AC-STEM) and chemically probed by hydrogen temperature-programmed reduction (H 2 -TPR). The results suggest that over this entire range of loadings, Fe was present as dispersed species, with only a very small fraction of Fe 2 O 3 aggregates, at the highest Fe loading in oxide phase. The in situ sulfidation of Fe/Al 2 O 3 resulted in the formation of a highly active and selective PDH catalyst. The highest activity with 52% propane conversion and ∼99% propylene selectivity at 560 °C was obtained for the 6.4 Fe/Al 2 O 3 -S catalyst, suggesting that this is the highest amount of Fe that could be fully dispersed on the support in sulfided form. XRD and AC-STEM indicated the absence of any crystalline iron sulfide aggregates after sulfidation and reaction. H 2 -TPR results indicated that the amount of the reducible Fe sites in the sulfided catalyst remained constant above monolayer coverage, and increasing loading did not increase the number of reducible Fe sites. Consistent with these results, the reactivity per gram of catalyst showed no increase with Fe loading above monolayer coverage, suggesting that additional Fe remains conformal to the alumina surface.

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Section: Introductionmentioning

confidence: 99%

Sulfur Tolerant Subnanometer Fe/Alumina Catalysts for Propane Dehydrogenation

Sharma

Purdy

Page

et al. 2021

ACS Appl. Nano Mater.

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“…Pure iron is known to suffer from runaway coking under PDH 44,60 conditions, while other Fe-based materials, such as Fe 3 C 44 and FeS, 50,51 have shown high coke resistance. Here, we perform GCMC and ab initio thermodynamics analyses to better understand why these materials are resistant to coke formation.…”

Section: Coke Formation On Iron Carbide Iron Sulfide and Fe/al Alloysmentioning

confidence: 99%

“…In this work, we employ GCMC‐DFT to determine the thermodynamic stability of coke formations on various Fe‐based surfaces. We first perform GCMC‐DFT simulations on the stable surfaces of pure iron, 44,60 iron carbide, 44 and iron sulfide, 50,51 as they all have shown different levels of coke resistance in experimental PDH studies. An alloy of iron and aluminum, Al 13 Fe 4 , that showed high stability during the semihydrogenation of acetylene and hydrogenation of butadiene, also is tested as a candidate PDH catalyst 64,65 .…”

Section: Introductionmentioning

confidence: 99%

“…Coke formation on catalyst surfaces is a major cause of catalyst deactivation in several industrial reactions involving hydrocarbon-rich environments, such as Fischer-Tropsch synthesis, [33][34][35][36] methane reforming, [37][38][39][40] CO 2 reduction, 41 fluid catalytic cracking, 42,43 and hydrocarbon dehydrogenation. 44,45 Various strategies have been developed to suppress coke formation, typically by adding promoters and dopants, [46][47][48] forming metal phosphides or sulfides, [49][50][51][52] forming nitrides or carbides, 44,53 or alloying with less carbophilic metals. [54][55][56] The particular interest in this work is the suppression of coke formation during nonoxidative propane dehydrogenation (PDH).…”

mentioning

confidence: 99%

“…Sun et al 46,47,61 found that coke formation can be suppressed during PDH by either adding sulfate during the catalyst preparation stage or by cofeeding SO 2 with the hydrocarbon reactants. Watanabe et al 50,51 found that the iron sulfide formed in situ by cofeeding H 2 S can suppress coke build-up. Similarly, Tan et al 44 showed that adding phosphate during the catalyst preparation stage greatly increased the coking resistance of Fe-based PDH catalysts.…”

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confidence: 99%

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Modeling phase formation on catalyst surfaces: Coke formation and suppression in hydrocarbon environments

Wang

Senftle

2021

AIChE Journal

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We develop a simulation toolset employing density functional theory in conjunction with grand canonical Monte Carlo (GCMC) to study coke formation on Fe-based catalysts during propane dehydrogenation (PDH). As expected, pure Fe surfaces develop stable graphitic coke structures and rapidly deactivate. We find that coke formation is markedly less favorable on Fe 3 C and FeS surfaces. Fe-Al alloys display varying degrees of coke resistance, depending on their composition, suggesting that they can be optimized for coke resistance under PDH conditions. Electronic structure analyses show that both electron-withdrawing effects (on Fe 3 C and FeS) and electron-donating effects (on Fe-Al alloys) destabilize adsorbed carbon. On the alloy surfaces, a geometric effect also isolates Fe sites and disrupts the formation of graphitic carbon networks. This work demonstrates the utility of GCMC for studying the formation of disordered phases on catalyst surfaces and provides insights for improving the coke resistance of Fe-based PDH catalysts.

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