Surface-dependent activity of model CoMoS hydrotreating catalysts

Castro, Ricardo Garcia de; Devers, Élodie; Digne, Mathieu; Lamic‐Humblot, Anne‐Félicie; Pirngruber, Gerhard D.; Carrier, Xavier

doi:10.1016/j.jcat.2021.01.026

Cited by 17 publications

(46 citation statements)

References 60 publications

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“…These results are in line with Mo sulfidation trends observed at 400 °C on both catalyst formulations. This generalized increase in promotion extents is following the increase in Mo sulfidation upon TEG additivation, as it was previously shown that Co promotion is intimately related to Mo sulfidation [23] …”

Section: Resultssupporting

confidence: 53%

“…In the case of model planar catalysts, the occurrence of defects is minimal, as suggested by AFM imaging of clean wafers of all four crystal orientations (See Supporting Information). However, single crystals exhibit defined Al−OH surface sorption sites with metal/support interactions of diverse nature as previously shown [20,21,23,24] . For instance, R(1

\overset{1}{true}

02) plane‐based catalysts exhibit mainly Al 4c ‐μ 1 −OH sites, responsible for strong metal‐support interactions, while C(0001) plane‐based ones display Al 6c ‐μ 2 −OH sites, associated to weaker interactions [20,21,23,24] .…”

Section: Resultsmentioning

confidence: 58%

“…Thus, in order to identify the effect of TEG, the impact of the calcination step on metal sulfidation should be discerned beforehand. In addition, in order to study the impact of phosphorus on the genesis of the promoted active phase in calcined catalysts, both average sulfidation and promotion extents from CoMo catalysts (reported in a previous contribution [23] ) will be confronted to those of CoMoP catalysts. Such descriptors were obtained through XPS analysis of model catalysts sulfided at 300 °C and 400 °C (Figure 1).…”

Section: Resultsmentioning

confidence: 99%

“… Sulfidation degree (left) and promotion extent (right) of dried and calcined model CoMoP catalysts supported on the C(0001), A(11

\overset{2}{true}

0), M(10

\overset{1}{true}

0) and R(1

\overset{1}{true}

02) planes of α‐Al 2 O 3 prepared by impregnation from a solution with P/Mo=0.57 and Co/Mo=0.5 sulfided at 300 and 400 °C. Sulfidation and promotion extents of calcined model CoMo catalysts without P prepared by impregnation (Co/Mo=0.5 [23] ) are presented as reference (marked as CoMo in the Figure).…”

Section: Resultsmentioning

confidence: 99%

“…demonstrated that the genesis of the active phase is surface‐dependent, with different surface sites leading to characteristic trends in sulfidation extent and Mo dispersion. More recent contributions sought to bridge the gap between model and industrial hydrotreating catalysts by studying the surface‐dependent nature of phosphorus doping and cobalt promotion under such approach [23,24] . These studies not only revealed a surface‐dependent interaction of phosphorus precursors with the support, but most remarkably, that intrinsic hydrodesulfurization activity of Co‐promoted catalysts is surface‐dependent, with active phase‐support interactions of intermediate strength leading to the highest catalytic activity [23,24] …”

Section: Introductionmentioning

confidence: 99%

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Role of Phosphorus and Triethylene Glycol Incorporation on the Activity of Model Alumina‐Supported CoMoS Hydrotreating Catalysts

et al. 2022

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Environmental regulations concerning fuel‐related sulfur emissions are currently experiencing worldwide expansion. This is motivating the research and development of improved hydrotreating (HDT) catalysts with carefully engineered synthesis methods that maximize activity as ultimate goal. In this contribution, the effect of phosphorus doping and triethylene glycol (TEG) incorporation on the genesis of the CoMoS phase of model HDT catalysts is assessed. Following a surface‐science approach, α‐Al2O3 single crystals with four orientations: C(0001), A(11true2‾ 0), M(10true1‾ 0), and R(1true1‾ 02) are used as model supports of the traditional γ‐Al2O3 support for the study of active phase‐support interactions at the molecular scale. The model catalysts are prepared by traditional impregnation of a solution containing metal and phosphorus precursors and TEG. The catalysts are characterized in the sulfide phase by XPS, XAS, TEM, and AFM, revealing that the calcination step is key in the emergence of distinctive metal‐support interactions, which are directly related to the nature of alumina surface sorption sites. In addition, TEG incorporation on dried catalysts increases metal sulfidation and enhances promotion with respect to non‐additivated systems, especially at mild sulfidation temperatures. The catalytic activity of the model catalysts is tested in a thiophene hydrodesulfurization reaction, revealing the following activity trend with respect to alumina surface orientations: A()112‾0 ≫ M()101‾0 >R()11‾02 , C(0001). This trend is identical to the one observed for non‐phosphorus doped non‐TEG additivated model systems, confirming the predominance of surface effects on the catalytic activity over those exerted by P and TEG. By transposing these results to the industrial γ‐Al2O3 support, the (100) facet would provide surface sites that lead to better performing catalysts. This could result in the development of novel supports, engineered to expose surface sites that maximize hydrotreating activity.

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Section: Resultssupporting

confidence: 53%

\overset{1}{true}

Section: Resultsmentioning

confidence: 58%

Section: Resultsmentioning

confidence: 99%

“… Sulfidation degree (left) and promotion extent (right) of dried and calcined model CoMoP catalysts supported on the C(0001), A(11

\overset{2}{true}

0), M(10

\overset{1}{true}

0) and R(1

\overset{1}{true}

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of Phosphorus and Triethylene Glycol Incorporation on the Activity of Model Alumina‐Supported CoMoS Hydrotreating Catalysts

et al. 2022

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Influence of the Ageing and Drying Steps of a CoMoP/γ‐Al₂O₃ Catalyst onto the Multi‐Scale Molybdenum Active Phase Organization

et al. 2023

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To study the influence of ageing and drying steps onto the multiscale Mo active phase arrangement (i. e. MoS2 slabs and slab aggregates), a series of highly loaded CoMoP/γ‐Al2O3 catalysts aged, unaged, dried or freeze‐dried were prepared and tested in toluene hydrogenation. Electron Probe Micro Analyses (EPMA) and Anomalous Small Angle X‐Ray Scattering (ASAXS) permit to highlight the influence of each preparation steps. A growth of Mo entities occurs during ageing along with metal diffusion inside the support and leads to longer slabs. The same occurs during drying with metal redistribution due to solvent evaporation. Concomitantly, a fragmentation of slab aggregates takes place and leads to numerous small slabs aggregates. Slab length and aggregates amount were found to drive the catalytic activity, which translates the relationship between activity, number of active sites and their accessibility. Conversely, macroscopic metal distribution into the extrudates appears to have no impact on the catalytic performance.

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Density functional theory study of the isomerization conversion of the cluster Co_nMoS (n = 1–5)

Wang,

Fang,

Wang

et al. 2023

Int J of Quantum Chemistry

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To investigate the isomerization transition of cluster ConMoS (n = 1–5), we employ density functional theory and transition state theory methods in this study. The cluster is optimized at the B3LYP/def2tzvp quantum chemical level. The results reveal eight isomerization reactions for the clusters ConMoS (n = 3, 5). Analyzing the activation energies shows a greater propensity for the isomerization transformation in the forward reaction compared to the reverse reaction. At room temperature, six isomerization transformation processes exhibit rapid conversion to the product configurations. Investigation of the equilibrium constants and application of the Arrhenius formula demonstrate that the cluster isomerization reactions are primarily driven by the forward reactions, with four reactions displaying efficient reactant to product conversion rates. Furthermore, there exists a consistent relationship between the structural complexity of the cluster and the change in entropy value. This study provides theoretical insights into reaction rates and optimization of reaction pathways, facilitating mutual validation and development between experimental and theoretical approaches.

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Surface-dependent activity of model CoMoS hydrotreating catalysts

Cited by 17 publications

References 60 publications

Role of Phosphorus and Triethylene Glycol Incorporation on the Activity of Model Alumina‐Supported CoMoS Hydrotreating Catalysts

Role of Phosphorus and Triethylene Glycol Incorporation on the Activity of Model Alumina‐Supported CoMoS Hydrotreating Catalysts

Influence of the Ageing and Drying Steps of a CoMoP/γ‐Al₂O₃ Catalyst onto the Multi‐Scale Molybdenum Active Phase Organization

Density functional theory study of the isomerization conversion of the cluster Co_nMoS (n = 1–5)

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Surface-dependent activity of model CoMoS hydrotreating catalysts

Cited by 17 publications

References 60 publications

Role of Phosphorus and Triethylene Glycol Incorporation on the Activity of Model Alumina‐Supported CoMoS Hydrotreating Catalysts

Role of Phosphorus and Triethylene Glycol Incorporation on the Activity of Model Alumina‐Supported CoMoS Hydrotreating Catalysts

Influence of the Ageing and Drying Steps of a CoMoP/γ‐Al2O3 Catalyst onto the Multi‐Scale Molybdenum Active Phase Organization

Density functional theory study of the isomerization conversion of the cluster ConMoS (n = 1–5)

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Influence of the Ageing and Drying Steps of a CoMoP/γ‐Al₂O₃ Catalyst onto the Multi‐Scale Molybdenum Active Phase Organization

Density functional theory study of the isomerization conversion of the cluster Co_nMoS (n = 1–5)