Periodic density functional theory study of ethylene hydrogenation over Co3O4 (1 1 1) surface: The critical role of oxygen vacancies

Lu, Jinhui; Song, Jiajia; Niu, Hongling; Pan, Lun; Zhang, Xiangwen; Wang, Li; Zou, Ji‐Jun

doi:10.1016/j.apsusc.2016.02.209

Cited by 33 publications

(21 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The combined theoretical–experimental results reported here have important implications in oxide catalyzed hydrogenation reactions. In particular, the importance of oxygen vacancies as the active sites for hydrogenation is consistent with the experimental and theoretical evidence for both ceria and other oxides. ,,− Doping of divalent metals such as Ni is known to enhance the formation of oxygen vacancies on ceria surfaces and thus the catalytic activity, as demonstrated here. This design principle could lead to more effective catalysts in the future.…”

Section: Discussionsupporting

confidence: 87%

Design of Effective Catalysts for Selective Alkyne Hydrogenation by Doping of Ceria with a Single-Atom Promotor

et al. 2018

View full text Add to dashboard Cite

Since the discovery that ceria is an active catalyst for selective hydrogenation of alkynes, there has been much debate on the catalytic mechanism. In this work, we propose, based on density functional theory (DFT) investigations, a mechanism that involves the heterolytic dissociation of H at oxygen vacancies of CeO(111), facilitated by frustrated Lewis pairs consisting of spatially separated O and Ce sites. The resulting O-H and Ce-H species effectively catalyze the hydrogenation of acetylene, avoiding the overstabilization of the CH* intermediate in a previously proposed mechanism. On the basis of our mechanism, we propose the doping of ceria by Ni as a means to create oxygen vacancies. Interestingly, the Ni dopant is not directly involved in the catalytic reaction, but serves as a single-atom promoter. Experimental studies confirm the design principles and demonstrate much higher activity for Ni-doped ceria in selective hydrogenation of acetylene. The combined results from DFT calculations and experiment provide a basis to further develop selective hydrogenation catalysts based on earth-abundant materials.

show abstract

Section: Discussionsupporting

confidence: 87%

Design of Effective Catalysts for Selective Alkyne Hydrogenation by Doping of Ceria with a Single-Atom Promotor

et al. 2018

View full text Add to dashboard Cite

show abstract

“…[5][6][7] Low pressure H2O/D2O exposure experiments have shown that hydroxyls are stable on the surface up to 570 K. 23 Further, H2 was also shown to dissociate easily over the (111) termination. 27 Therefore, any H2O or H2 impurity in the gas environment will likely produce hydroxyls. Third, the electronic effects of surface reduction are not addressed in most studies.…”

Section: Introductionmentioning

confidence: 99%

Surface Structure of Co₃O₄ (111) under Reactive Gas-Phase Environments

Yan

Sautet

2019

ACS Catal.

View full text Add to dashboard Cite

In this work, we thoroughly examined the structure of the Co3O4(111) surface in oxidative and reductive conditions, i.e. in equilibrium with realistic pressures of O2/H2O and H2/H2O, using density functional theory with self-interaction and dispersion corrections. We found that this surface is, in fact, hydroxylated under most reaction conditions, and that subjecting the surface to H2 increases surface Co 2+ concentration. Large structural distortions facilitate the reduction and stabilization of the Co-rich termination. At 423 K, hydroxylation readily occurs on both the Orich and Co-rich surfaces even at water pressure as low as 10 -15 bar, and non-dissociated water molecules appear on the O-rich surface when water pressure is above ~10 -11 bar. Our approach showed good agreement with hybrid functional calculations and vibrational spectroscopy experiments. Under most catalytic conditions, where water is present as a reactant, product, or impurity, we predict that the Co3O4(111) surface will be hydroxylated. Hydroxyls groups and structural distortions undoubtedly play large roles in shaping the surface's catalytic properties and interaction with supported structures. The results of the study show the necessity of the inclusion of hydroxylation and surface Co concentration in computational studies of Co3O4 and provide surface structures under various conditions to aid in future studies on structure and catalytic reactivity of Co3O4(111) used as a support or as an active phase.

show abstract

“…Recently, we reported that oxygen-deficient tungsten, iron oxides, and cobalt oxides are efficient catalysts for the hydrogenation of −NO 2 and CC groups. − Specifically, the catalytic activity of tungsten oxides varies considerably from WO 3 to WO 2.72 , that is, the activity linearly increases with the decrease of oxygen content in the oxides . This work not only suggests WO 3– x as a potential hydrogenation catalyst but also brings up one interesting question: how will the activity change if the oxygen content is further decreased?…”

Section: Introductionmentioning

confidence: 68%

Structure and Activity Transition from Oxidized to Metallic Tungsten for Catalytic Hydrogenation: A Density Functional Theory Study

et al. 2018

Self Cite

View full text Add to dashboard Cite

Oxide-based hydrogenation catalysts have attracted intensive interest, but the relationships between their composition, structure, and reaction mechanism are still ambiguous. Here, we conducted density functional theory (DFT) calculation on ethylene hydrogenation over WO 3 , WO 2.72 , WO 2 , and W catalysts to explore how the structure and catalytic activity change with the composition and explain why neither WO 3 nor metallic W is a good hydrogenation catalyst but WO 3−x is. Calculations on the geometric and electronic structures show a transition from semiconductor to metal-like with more W−W metal bonds appearing from the corresponding oxidized to metallic tungsten. Correspondingly, the H 2 dissociation mechanism changes from heterotypic on the semiconductor WO 3 and WO 2.72 to homotypic on the metal-like WO 2 and metallic W, and the adsorption strength of the dissociation product (2H) enhances from oxidized to metallic W. Calculations on the stepwise hydrogenation indicate that H 2 dissociation is the rate-limiting step (RLS) for WO 3 and WO 2.72 , whereas the following hydrogenation step (C 2 H 5 + H → C 2 H 6 ) is the RLS for WO 2 and W. By linear fitting the binding energies of H 2 , 2H, H + C 2 H 5 , and C 2 H 6 adsorptions, a perfect correlation between (H + C 2 H 5 ) and (2H) adsorptions is observed; thus, the catalytic activity and mechanism can be evaluated using 2H adsorption behavior as the descriptor. On the basis of the calculation results, we predict that the best ethylene hydrogenation activity will show at 2 < x < 2.72 for WO x . This work suggests that controlling the composition between the stoichiometric oxide and the metal may be an effective way to develop an active hydrogenation catalyst.

show abstract

Periodic density functional theory study of ethylene hydrogenation over Co3O4 (1 1 1) surface: The critical role of oxygen vacancies

Cited by 33 publications

References 46 publications

Design of Effective Catalysts for Selective Alkyne Hydrogenation by Doping of Ceria with a Single-Atom Promotor

Design of Effective Catalysts for Selective Alkyne Hydrogenation by Doping of Ceria with a Single-Atom Promotor

Surface Structure of Co₃O₄ (111) under Reactive Gas-Phase Environments

Structure and Activity Transition from Oxidized to Metallic Tungsten for Catalytic Hydrogenation: A Density Functional Theory Study

Contact Info

Product

Resources

About

Periodic density functional theory study of ethylene hydrogenation over Co3O4 (1 1 1) surface: The critical role of oxygen vacancies

Cited by 33 publications

References 46 publications

Design of Effective Catalysts for Selective Alkyne Hydrogenation by Doping of Ceria with a Single-Atom Promotor

Design of Effective Catalysts for Selective Alkyne Hydrogenation by Doping of Ceria with a Single-Atom Promotor

Surface Structure of Co3O4 (111) under Reactive Gas-Phase Environments

Structure and Activity Transition from Oxidized to Metallic Tungsten for Catalytic Hydrogenation: A Density Functional Theory Study

Contact Info

Product

Resources

About

Surface Structure of Co₃O₄ (111) under Reactive Gas-Phase Environments