Impact of proximity between NiMoS and zeolitic HY sites on cyclohexene hydroconversion: An infrared operando study of sulfide catalysts

Santos, Bruno M.; Zhao, Weitao; Zotin, José Luiz; Silva, Mônica A. P. da; Oliviero, Laetitia; Maugé, Françoise

doi:10.1016/j.jcat.2021.01.038

Cited by 9 publications

(3 citation statements)

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“…However, k HYD of DBT among spent catalysts only changed slightly. To further quantify the hydrogenation activity of spent catalysts, cyclohexene (CHE) hydrogenation was conducted as a model reaction. , The conversion of CHE may go through three possible routes: (1) dehydrogenation to benzene, (2) hydrogenation to cyclohexane, or (3) isomerization to methylcyclopentene and its subsequent hydrogenation to methylcyclopentane. , For the fresh and spent sulfided NiMo/Al 2 O 3 catalysts, only the hydrogenation route (HYD) was observed with cyclohexane as the only product.…”

Section: Resultsmentioning

confidence: 99%

“…27,28 The conversion of CHE may go through three possible routes: (1) dehydrogenation to benzene, (2) hydrogenation to cyclohexane, or (3) isomerization to methylcyclopentene and its subsequent hydrogenation to methylcyclopentane. 27,29 For the fresh and spent sulfided NiMo/Al 2 O 3 catalysts, only the hydrogenation route (HYD) was observed with cyclohexane as the only product. HYD of CHE is a first-order reaction, 28,29 and k HYD values of all tested catalysts are listed in Figure 2B.…”

Section: Catalytic Activities Of Fresh and Spent Catalysts In Probementioning

confidence: 99%

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Impact of Coprocessing Biocrude with Petroleum Stream on Hydrotreating Catalyst Stability

et al. 2022

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Coprocessing of biocrudes from hydrothermal liquefaction (HTL) of biomass and wastes with petroleum streams in refinery hydroprocessing has significant potential to accelerate the production of renewable transportation fuels in the near term. However, HTL biocrudes with some problematic characteristics can potentially cause faster deactivation of the catalysts, which is one of the biggest barriers to the adoption of biocrude in the current refinery process. In this work, we investigated the deactivation modes of a sulfide NiMo/Al2O3 hydrotreating catalyst used for coprocessing HTL biocrude (from wastewater sludge) with straight-run diesel. Spent catalysts were collected after coprocessing diesel with different biocrudes after >300 h time on stream and characterized by various techniques. Their catalytic activities were evaluated by model compound testing. Loss of catalyst activity was observed after coprocessing biocrudes. No structural change of the catalyst after coprocessing biocrudes was observed, and catalyst deactivation was largely due to catalyst fouling by carbonaceous species and metal contaminants (such as Fe and K) from biocrudes. Inorganic contaminant deposition leads to the external coating of the catalyst pellets on the top of the reactor, whereas the carbonaceous species potentially bind near the sulfide active phase, thereby blocking access to the active edge sites. Pretreatment of the HTL biocrude can reduce problematic species and alleviate catalyst deactivation during coprocessing.

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Section: Resultsmentioning

confidence: 99%

Section: Catalytic Activities Of Fresh and Spent Catalysts In Probementioning

confidence: 99%

Impact of Coprocessing Biocrude with Petroleum Stream on Hydrotreating Catalyst Stability

et al. 2022

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“…Therefore, the catalytically significant rGO/MoO 2 sites should be quantifiable by the equivalents of poison required to suppress activity. The use of pyridine has previously been reported to poison Lewis acidic catalysts. − In the present assay, 15 min conversions of benzaldehyde were monitored as increasing equivalents of pyridine were titrated into the reaction mixture (Figure ). Linear responses suggest that the poison reacts with the active sites uniformly and proportionately, and extrapolation to zero benzaldehyde conversion indicates that 69 ± 2% of the Mo sites are catalytically significant.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Structure–Activity Characterization of a Single-Site MoO₂ Catalytic Center Anchored on Reduced Graphene Oxide

Liu

Das

et al. 2021

J. Am. Chem. Soc.

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Molecularly derived single-site heterogeneous catalysts can bridge the understanding and performance gaps between conventional homogeneous and heterogeneous catalysis, guiding the rational design of next-generation catalysts. While impressive advances have been made with well-defined oxide supports, the structural complexity of other supports and the nature of the grafted surface species present an intriguing challenge. In this study, single-site Mo(O) 2 species grafted onto reduced graphene oxide (rGO/MoO 2 ) are characterized by XPS, DRIFTS, powder XRD, N 2 physisorption, NH 3 -TPD, aqueous contact angle, active site poisoning assay, Mo EXAFS, model compound single-crystal XRD, DFT, and catalytic performance. NH 3 -TPD reveals that the anchored MoO 2 moiety is not strongly acidic, while Mo 3d 5/2 XPS assigns the oxidation state as Mo(VI), and XRD shows little rGO periodicity change on MoO 2 grafting. Contact angle analysis shows that MoO 2 grafting consumes rGO surface polar groups, yielding a more hydrophobic surface. The rGO/MoO 2 DRIFTS assigns features at 959 and 927 cm −1 to the symmetric and antisymmetric MoO stretching modes, respectively, of an isolated cis-(O MoO) moiety, in agreement with DFT computation. Moreover, the Mo EXAFS rGO/MoO 2 structural data are consistent with isolated (C−O) 2 −Mo(O) 2 species having two MoO bonds and two Mo−O bonds at distances of 1.69(3) and 1.90(3) Å, respectively. rGO/MoO 2 is also more active than the previously reported AC/MoO 2 catalyst, with reductive carbonyl coupling TOFs approaching 1.81 × 10 3 h −1 . rGO/MoO 2 is environmentally robust and multiply recyclable with 69 ± 2% of the Mo sites catalytically significant. Overall, rGO/MoO 2 is a structurally well-defined and versatile single-site Mo(VI) dioxo heterogeneous catalytic system. Recently, this laboratory reported the first single-site

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Tetradecylamine-induced assembly of Mo and Al precursors to prepare efficient NiMoS/Al2O3 catalysts for ultradeep hydrodesulfurization

Huang

Fan

2022

Applied Catalysis B: Environmental

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Impact of proximity between NiMoS and zeolitic HY sites on cyclohexene hydroconversion: An infrared operando study of sulfide catalysts

Cited by 9 publications

References 50 publications

Impact of Coprocessing Biocrude with Petroleum Stream on Hydrotreating Catalyst Stability

Impact of Coprocessing Biocrude with Petroleum Stream on Hydrotreating Catalyst Stability

Synthesis and Structure–Activity Characterization of a Single-Site MoO₂ Catalytic Center Anchored on Reduced Graphene Oxide

Tetradecylamine-induced assembly of Mo and Al precursors to prepare efficient NiMoS/Al2O3 catalysts for ultradeep hydrodesulfurization

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Impact of proximity between NiMoS and zeolitic HY sites on cyclohexene hydroconversion: An infrared operando study of sulfide catalysts

Cited by 9 publications

References 50 publications

Impact of Coprocessing Biocrude with Petroleum Stream on Hydrotreating Catalyst Stability

Impact of Coprocessing Biocrude with Petroleum Stream on Hydrotreating Catalyst Stability

Synthesis and Structure–Activity Characterization of a Single-Site MoO2 Catalytic Center Anchored on Reduced Graphene Oxide

Tetradecylamine-induced assembly of Mo and Al precursors to prepare efficient NiMoS/Al2O3 catalysts for ultradeep hydrodesulfurization

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Synthesis and Structure–Activity Characterization of a Single-Site MoO₂ Catalytic Center Anchored on Reduced Graphene Oxide