Control of surface reactivity towards unsaturated C C bonds and H over Ni-based intermetallic compounds in semi-hydrogenation of acetylene

Song, Yuanjun; Laursen, Siris

doi:10.1016/j.jcat.2019.02.018

Cited by 25 publications

(33 citation statements)

References 140 publications

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“…However, our calculation results demonstrate that ethylene tends to adsorb on Ni(111) with one C atom at a top site above a Ni atom and the other C at a hollow site (Figure a1), which was 0.12 eV more stable than the π mode. Similar adsorption geometries of ethylene were found in calculations of acetylene hydrogenation. − Furthermore, when the H atom was co-adsorbed on the linear hollow site, the π mode will covert to the σ-hollow mode. The adsorption energies of ethylene and H atom were −1.40 and −0.47 eV, respectively.…”

Section: Results and Discussionsupporting

confidence: 71%

Correlating C═C, C═O, and C═N Hydrogenation Activity with Hydrogen Binding Energies on Ni–Fe Bimetallic Catalysts

et al. 2020

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Ni–Fe bimetallic catalysts have been found active in various hydrogenation reactions. Previous reports have hypothesized many explanations to demonstrate the promotion effect of Fe. However, these theories cannot predict the falling part of the volcanic curve of the hydrogenation activity with the Fe/(Ni + Fe) ratio. Here, we studied the hydrogenation pathways over Ni monometallic and Ni–Fe bimetallic sites with density functional theory (DFT) calculations. Ethylene, furfural, and methanimine were chosen as the representative reactants with CC, CO, and CN, respectively. The energy profiles on Ni3, Ni2Fe, and NiFe2 sites were calculated. The results showed that the activation energy of the rate-determining step follows the trend Ni2Fe < NiFe2 < Ni3 for all three hydrogenation reactions. Therefore, the Ni3Fe1 catalyst was predicted to be the most active because it has the highest density of Ni2Fe sites. Furthermore, the H binding energy was proved to be an efficient descriptor for the activation energy and hydrogenation activity. With a decrease in the H binding energy, the activation energy of hydrogenation reactions increased, indicating lower reaction activity. To verify our calculation results, the Ni monometallic and Ni–Fe bimetallic catalysts were synthesized with the co-impregnation method. The catalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and were evaluated in ethylene hydrogenation reactions. As predicted by DFT calculations, the activity showed a volcanic relationship with the Fe/(Ni + Fe) ratio with Ni3Fe1 located at the top.

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Section: Results and Discussionsupporting

confidence: 71%

Correlating C═C, C═O, and C═N Hydrogenation Activity with Hydrogen Binding Energies on Ni–Fe Bimetallic Catalysts

et al. 2020

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“…Additionally, the complete absence of CH 4 as a product under WGS conditions illustrates that limited hydrogenated kinetics over Ni + Ga IMCs is a general feature and not specific to the wet-reforming condition. This view is in line with our previous studies focused on controlling hydrogenation. ,, This trend is further underscored by the fact that CH 4 is often a major unselective product in WGS when catalyzed by platinum group metals. − It is interesting to note that despite the as-reduced Ni 3 Ga presenting a Ni-dominated surface composition, its performance in the water gas shift was very similar to the Ni 3 Ga-terminated annealed Ni 3 Ga catalyst.…”

Section: Resultssupporting

confidence: 83%

“…Each of these approaches clearly limits rehydrogenation kinetics by modifying the stability of carbonaceous or atomic H intermediates or the fundamental nature of the hydrogen-surface bond. A similar trend has been identified in prior studies by others and ourselves in the surface chemistry of TM solid compounds formed from TMs combined with similarly sized p-block elements. ,, Elevated kinetic barriers for H-transfer have been connected to the nature of the H-surface bond and the presence of covalent-like bonding within the TM solid compound as a function of the selective or full hybridization between the d- and p-states of constituent elements. ,,, This effect may help to avoid the unselective loss of H, but may also detrimentally affect H 2 evolution rates in reforming reactions. The studies presented herein clarify the beneficial effect of this newly accessible surface chemistry.…”

Section: Introductionsupporting

confidence: 75%

Controlling Selectivity and Stability in the Hydrocarbon Wet-Reforming Reaction Using Well-Defined Ni + Ga Intermetallic Compound Catalysts

Song

Laursen

2020

ACS Catal.

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In this study, we present the use of compositionally and structurally well-defined, oxide-supported nanoparticle Ni + Ga intermetallic compound (IMC) catalysts in the wet reforming of propane. The definition of the IMC catalysts allowed for more direct connections to be made between catalyst bulk and surface compositions and catalyst performance in wet reforming. We show that Ni + Ga catalysts exhibit comparable or better rates of reaction on a per-site basis and improved stability in comparison to other leading formulations. We also demonstrate excellent control over product selectivity as a function of Ni + Ga IMC bulk and surface compositions with nearly ideal selectivity toward CO2/H2 or CO/H2 achieved. Selectivity toward the production of smaller hydrocarbons could also be suppressed significantly due to uniquely limited rehydrogenation kinetics of the Ni + Ga IMCs. Our studies also shed light on the stability of Ni + Ga IMCs under reaction conditions and how high conversion in reactions that involve many strongly bound reaction intermediates can lead to IMC phase relaxation to the most stable phase with concomitant surface composition and catalytic performance changes. Correlations between surface chemistry and catalyst performance were afforded by both the well-defined nature of the IMCs and computational surface science studies.

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“…This suggested that the In concentration near the surface layers can be increased by increasing the In loading in the catalyst. This phenomenon was also observed in a range of bimetallic materials, intermetallic compounds, and transition metal ceramics. ,− …”

Section: Results and Discussionmentioning

confidence: 71%

Selective and Stable In-Promoted Fe Catalyst for Syngas Conversion to Light Olefins

Shi

Johnson

et al. 2021

ACS Catal.

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A selective and stable alumina-supported In-promoted Fe catalyst (10 mol % In based on Fe) was discovered for converting syngas (2:1 H2/CO ratio) to olefins with high selectivity (45% with CO2 included) and a remarkable stability (72 h run) at a CO conversion of 10% at 400 °C and 5 bar. The X-ray photoelectron spectroscopy results indicated that incorporating In into Fe catalysts changed the chemical bonding state of Fe and Fe/In composition near the surface layers, which affected the catalytic reactivity. Steady-state isotopic transient kinetic analysis showed that more stable CHx fragments are present on the catalyst surface when incorporating In into Fe, which can promote C–C coupling reaction toward olefins. Our study demonstrates that introducing In into Fe catalysts on Al2O3 support can lower CO activation abilities. It has more impacts on lowering hydrogenation activity, which permits more C–C couplings and like of “ene” hydrogenation. Moreover, weakening CO adsorption both in terms of sites and strength encouraged CO toward hydrocarbons rather than CO2.

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Control of surface reactivity towards unsaturated C C bonds and H over Ni-based intermetallic compounds in semi-hydrogenation of acetylene

Cited by 25 publications

References 140 publications

Correlating C═C, C═O, and C═N Hydrogenation Activity with Hydrogen Binding Energies on Ni–Fe Bimetallic Catalysts

Correlating C═C, C═O, and C═N Hydrogenation Activity with Hydrogen Binding Energies on Ni–Fe Bimetallic Catalysts

Controlling Selectivity and Stability in the Hydrocarbon Wet-Reforming Reaction Using Well-Defined Ni + Ga Intermetallic Compound Catalysts

Selective and Stable In-Promoted Fe Catalyst for Syngas Conversion to Light Olefins

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