Effect of nanostructuring on the interaction of CO<sub>2</sub>with molybdenum carbide nanoparticles

Jimenez-Orozco, Carlos; Figueras, Marc; Flórez, Elizabeth; Viñes, Francesc; Rodríguez, José A.; Illas, Francesc

doi:10.1039/d2cp01143c

Cited by 7 publications

(27 citation statements)

References 41 publications

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“…Thus, the three coverage situations chosen allow one to investigate the influence of this magnitude on the energy profile without needing to rely on building phase diagrams from atomistic thermodynamics that, given the complexity of the nanoparticles, will involve a very high conformational entropy, thus involving an exceedingly large number of situations. It should be noted that there are differences in adsorption configurations of adsorbates on surfaces and nanoparticles, see Figure S3 in SI, which are due to structural and electronic differences between extended surfaces and nanoparticles as described in a prior report . The spatial distribution of C and Mo atoms at the surfaces is defined by their crystal structure while the location of C and Mo atoms in the MoC y nanoparticles depends on size, morphology, and stoichiometry.…”

Section: Results and Discussionmentioning

confidence: 88%

“…It should be noted that there are differences in adsorption configurations of adsorbates on surfaces and nanoparticles, see Figure S3 in SI, which are due to structural and electronic differences between extended surfaces and nanoparticles as described in a prior report. 18 The spatial distribution of C and Mo atoms at the surfaces is defined by their crystal structure while the location of C and Mo atoms in the MoC y nanoparticles depends on size, morphology, and stoichiometry. A detailed description of similarities and differences of ethylene adsorbed on molybde-num carbide surfaces and MoC y nanoparticles was reported in a previous work.…”

Section: Effect Of Hydrogen Coverage In the Ethylene Hydrogenation Me...mentioning

confidence: 99%

“…This was modeled by a variety of nanostructures ranging from Mo 4 C 6 to Mo 32 C 32 . Moreover, for the smallest NPs involving from Mo 4 C 6 to Mo 6 C 6 , a total of 60 isomers were found in a rather narrow range of energy, a clear indication of the variability and richness of the NPs as compared to extended surfaces. For C 2 H 4 adsorbed on MoC y NPs with a Mo/C atomic ratio <1.1, an elongation of the CC bond and a change in the typical sp 2 hybridization to an sp 3 -like hybridization was found .…”

Section: Introductionmentioning

confidence: 97%

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Ethylene Hydrogenation Molecular Mechanism on MoC_y Nanoparticles

et al. 2023

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Ethylene hydrogenation catalyzed by MoC y nanoparticles has been studied by means of density functional theory methods and several models. These include MetCar (Mo 8 C 12 ), Nanocube (Mo 14 C 13 ), and Mo 12 C 12 nanoparticles as representatives of experimental MoC y nanostructures. The effect of hydrogen coverage has been studied in detail by considering low-, intermediate-, and highhydrogen regimes. The calculated enthalpy and energy barriers show that ethylene hydrogenation is feasible on the MetCar, Mo 12 C 12 , and Nanocube but at low, medium, and high hydrogen coverages, respectively. An additional step, related to the H* migration from a Mo to a C site in the nanoparticle, has been found to be the key to establishing the best hydrogenation system. In most cases, the reactions are exothermic, featuring low hydrogenation energy barriers, especially for the Nanocube at high hydrogen coverage. In addition, the calculated adsorption Gibbs free energy shows that, for this system, the C 2 H 4 adsorption is feasible in the 300− 400 K temperature range and pressures from 10 −10 to 2 atm. For the hydrogenation steps, calculated transition state theory rates show that the overall process is limited by the first hydrogenation step (C 2 H 4 → C 2 H 5 ) at temperatures of 330−400 K. However, at the lower temperatures of 300−320 K, the reaction rates are comparable for the two steps. The present results indicate that the Mo 14 C 13 Nanocube models of MoC y nanoparticles exhibit appropriate thermodynamic and kinetic features to catalyze ethylene hydrogenation at a high-hydrogen-coverage regime. The present findings provide a basis for understanding the chemistry of active MoC y catalysts, suggest appropriate working conditions for the reaction to proceed, and provide a basis for future experimental studies.

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Section: Results and Discussionmentioning

confidence: 88%

Section: Effect Of Hydrogen Coverage In the Ethylene Hydrogenation Me...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Ethylene Hydrogenation Molecular Mechanism on MoC_y Nanoparticles

et al. 2023

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“…[160a] Thus it suggests that the catalytic behavior and selectivity of TMCs may be engineered just like surface chemistry and catalytic behavior of metal oxides [159] and RWGS-catalyzed supported gold catalyst. [160b] Recently, Jimenez-Orozco et al [166] studied the effects of C/ M stoichiometric and non-stoichiometric ratio on nanostructures of molybdenum carbide nanoparticles and adsorption behavior of CO 2 . [161] These nanoclusters were categorized in three different groups based on their number of atoms: small cluster (up to 12 atoms), intermediate clusters (up to 22 atoms), and large clusters (up to 64 atoms).…”

Section: Impact Of Carbon/metal Ratio In Catalytic Reactivity Of Tmcsmentioning

confidence: 99%

“…Recently, Jimenez‐Orozco et al [166] . studied the effects of C/M stoichiometric and non‐stoichiometric ratio on nanostructures of molybdenum carbide nanoparticles and adsorption behavior of CO 2 [161] .…”

Section: Role Of Tmcs In Co2 Hydrogenation Reactionmentioning

confidence: 99%

Recent Advances in Carbon Dioxide Adsorption, Activation and Hydrogenation to Methanol using Transition Metal Carbides

2022

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The inevitable emission of carbon dioxide (CO 2 ) due to the burning of a substantial amount of fossil fuels has led to serious energy and environmental challenges. Metal-based catalytic CO 2 transformations into commodity chemicals are a favorable approach in the CO 2 mitigation strategy. Among these transformations, selective hydrogenation of CO 2 to methanol is the most promising process that not only fulfils the energy demands but also re-balances the carbon cycle. The investigation of CO 2 adsorption on the surface of heterogeneous catalyst is highly important because the formation of various intermediates which determines the selectivity of product. Transition metal carbides (TMCs) have received considerable attention in recent years because of their noble metal-like reactivity, ceramic-like properties, high chemical and thermal stability. These features make them excellent catalytic materials for a variety of transformations such as CO 2 adsorption and its conversion into value-added chemicals. Herein, the catalytic properties of TMCs are summarize along with synthetic methods, CO 2 binding modes, mechanistic studies, effects of dopant on CO 2 adsorption, and carbon/metal ratio in the CO 2 hydrogenation reaction to methanol using computational as well as experimental studies. Additionally, this Review provides an outline of the challenges and opportunities for the development of potential TMCs in CO 2 hydrogenation reactions.

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The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H₂Dissociation and Formation of Low and High Coverages

2023

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Tungsten carbide (WC) displays a Pt-like behavior in catalysis, applied in hydrogenation processes. Numerous theoretical studies have modeled the behavior and use of adsorbed hydrogen without obtaining a general picture, missing basic links between H 2 dissociation and generation of high surface coverage (Θ H > 0.5 ML). Here, the capability of C-and Wterminations of the α-WC(0001) surface is analyzed to dissociate several H 2 molecules to produce coverages, Θ H , ranging from low to very high values (0.13 < Θ H < 2.00 ML). Density functional theory and an ab initio atomistic thermodynamic were used to achieve the conditions for H 2 dissociation. The WCÀ C surface has higher capacity to dissociate H 2 molecules than WCÀ W. However, both surfaces can reach full surface coverage, Θ H = 1 ML, at mild ambient conditions, T = 300 K and P = 1 atm, and even up to 500 K at low and high pressures. The H-adatoms on WCÀ W are more labile than on WCÀ C. The binding of adsorbates is hindered at high Θ H , implying a need to modulate Θ H according to the application. The results give the basis to understand the capabilities of WC-based catalysts in hydrogenation-related reactions, with the advantage of WC being a hydrogen reservoir at mild practical catalytic conditions.

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Effect of nanostructuring on the interaction of CO₂with molybdenum carbide nanoparticles

Abstract: Transition metal carbides are emerging alternative catalysts to Pt-group metals for the transformation of CO2 and methane greenhouse gases. Recently, the effect of nanostructuring of such carbides has started to...

Cited by 7 publications

References 41 publications

Ethylene Hydrogenation Molecular Mechanism on MoC_y Nanoparticles

Ethylene Hydrogenation Molecular Mechanism on MoC_y Nanoparticles

Recent Advances in Carbon Dioxide Adsorption, Activation and Hydrogenation to Methanol using Transition Metal Carbides

The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H₂Dissociation and Formation of Low and High Coverages

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Effect of nanostructuring on the interaction of CO2with molybdenum carbide nanoparticles

Abstract: Transition metal carbides are emerging alternative catalysts to Pt-group metals for the transformation of CO2 and methane greenhouse gases. Recently, the effect of nanostructuring of such carbides has started to...

Cited by 7 publications

References 41 publications

Ethylene Hydrogenation Molecular Mechanism on MoCy Nanoparticles

Ethylene Hydrogenation Molecular Mechanism on MoCy Nanoparticles

Recent Advances in Carbon Dioxide Adsorption, Activation and Hydrogenation to Methanol using Transition Metal Carbides

The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H2Dissociation and Formation of Low and High Coverages

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Product

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Effect of nanostructuring on the interaction of CO₂with molybdenum carbide nanoparticles

Ethylene Hydrogenation Molecular Mechanism on MoC_y Nanoparticles

Ethylene Hydrogenation Molecular Mechanism on MoC_y Nanoparticles

The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H₂Dissociation and Formation of Low and High Coverages