scholarly journals Ab Initio and Density Functional Theory Evidence on the Rate-Limiting Step in the Morita−Baylis−Hillman Reaction

2008 ◽  
Vol 10 (16) ◽  
pp. 3651-3651
Author(s):  
Dipankar Roy ◽  
Raghavan B. Sunoj
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Functional Theory ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

scholarly journals Mechanism of Guaiacol Hydrodeoxygenation on Cu (111): Insights from Density Functional Theory Studies

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 523
Author(s):  
Destiny Konadu ◽  
Caroline Rosemyya Kwawu ◽  
Richard Tia ◽  
Evans Adei ◽  
Nora Henriette de Leeuw
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Reaction Path ◽  
Binding Energies ◽  
Functional Theory ◽  
Thermodynamics And Kinetics ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
The Density Functional Theory ◽  
Rate Limiting

Understanding the mechanism of the catalytic upgrade of bio-oils via the process of hydrodeoxygenation (HDO) is desirable to produce targeted oxygen-deficient bio-fuels. We have used calculations based on the density functional theory to investigate the reaction mechanism of HDO of guaiacol over Cu (111) surface in the presence of H2, leading to the formation of catechol and anisole. Our analysis of the thermodynamics and kinetics involved in the reaction process shows that catechol is produced via direct demethylation, followed by dehydrogenation of –OH and re-hydrogenation of catecholate in a concerted fashion. The de-methylation step is found to be the rate-limiting step for catechol production with a barrier of 1.97 eV. Formation of anisole will also proceed via the direct dehydroxylation of guaiacol followed by hydrogenation. Here, the rate-limiting step is the dehydroxylation step with an energy barrier of 2.07 eV. Thermodynamically, catechol formation is favored while anisole formation is not favored due to the weaker interaction seen between anisole and the Cu (111) surface, where the binding energies of guaiacol, catechol, and anisole are -1.90 eV, −2.18 eV, and −0.72 eV, respectively. The stepwise barriers also show that the Cu (111) surface favors catechol formation over anisole as the rate-limiting barrier is higher for anisole production. For catechol, the overall reaction is downhill, implying that this reaction path is thermodynamically and kinetically preferred and that anisole, if formed, will more easily transform.

scholarly journals Density functional theory calculations on the CO catalytic oxidation on Al-embedded graphene

RSC Advances ◽  
2014 ◽  
Vol 4 (39) ◽  
pp. 20290-20296 ◽  
Author(s):  
Q. G. Jiang ◽  
Z. M. Ao ◽  
S. Li ◽  
Z. Wen
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Energy Barrier ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Co Catalytic Oxidation ◽  
Rate Limiting

The energy barrier of the CO oxidation for the rate limiting step on Al-embedded graphene is only 0.32 eV.

THEORETICAL INVESTIGATION ON THE ACTIVATION OF ETHANE VIA NICKEL ATOM CATALYSIS

2007 ◽  
Vol 06 (02) ◽  
pp. 323-330 ◽  
Author(s):  
LAI-CAI LI ◽  
JUN-LING LIU ◽  
JING SHANG ◽  
XIN WANG ◽  
NING-BEW WONG
Keyword(s):  
Density Functional ◽  
Bond Activation ◽  
Theoretical Work ◽  
Nickel Atom ◽  
Functional Theory ◽  
Activation Pathway ◽  
Rate Determining Step ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

The reaction mechanism of the activation of ethane by nickel atom has been investigated by density functional theory (DFT). The geometries and vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311 + +G(d, p) level. Two main pathways, C – C bond activation and C – H bond activation, are identified. In former channel, the rate-limiting step is found to be hydrogen-transferring step with a high barrier of 227 kJ · mol-1. In the C – H bond activation pathway, the second hydrogen-transferring step is the rate-determining step of the whole reaction. The barrier of the step is 71 kJ · mol-1. Our results show that the studied reaction would undergo along C – H bond activation pathway to form the products H 2 molecule and Ni ⋯ethene complex. The present theoretical work indicates that Ni atom is more active than Ni + cation in activating ethane.

Boron Diffusion Mechanism in Silicon Oxide Using AB Initio Methods

2000 ◽  
Vol 610 ◽  
Author(s):  
V. Zubkov ◽  
J. P. Senosiain ◽  
S. Aronowitz ◽  
V. Sukharev ◽  
C. B. Musgrave
Keyword(s):  
Density Functional ◽  
Silicon Oxide ◽  
Diffusion Mechanism ◽  
Activation Energies ◽  
Boron Diffusion ◽  
Functional Theory ◽  
Model Cluster ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

AbstractDensity functional theory was employed to explore the diffusion mechanism of boron in amorphous silicon oxide. The oxide was modeled with clusters of various sizes, and both neutral boron atoms and cations were considered. Three stable structures were found where B (or B+) was inserted into oxide: one in which B (or B+) is divalent and two in which B (or B+) is trivalent. Boron diffusion through silicon oxide proceeds as a sequence of B hops from one inserted position to another. For neutral boron the rate limiting step is B hop from one of trivalent structures to a divalent one with activation energies (Ea) in the range of 2.0-3.1 eV, depending on the model cluster. In the case of a cation the rate-limiting step is the B+ hop over the O atom in a divalent structure Si-B+-O-Si with calculated Ea of 2.4-2.8 eV. Experimental activation energies for B diffusion in silicon oxide are in the 2.3 - 4.2 eV range. Our results suggest that both neutral and cation boron can participate in B diffusion in oxide.

scholarly journals Density Functional Theory and Complete Basis Set Ab Initio Computational Study of Five-, Six-, Seven- and Eight-hydrogen Coordinated Carbon Cations

1999 ◽  
Vol 23 (8) ◽  
pp. 502-503
Author(s):  
Branko S. Jursic
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Computational Study ◽  
Basis Set ◽  
Functional Theory ◽  
Complete Basis ◽  
Complete Basis Set ◽  
High Level

High level ab initio and density functional theory studies are performed on highly protonated methane species.

scholarly journals Ab initio molecular dynamics of hydrogen on tungsten surfaces

2021 ◽  
Author(s):  
Alberto Rodríguez-Fernández ◽  
Laurent Bonnet ◽  
Pascal Larrégaray ◽  
Ricardo Díez Muiño
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Molecular Dynamics ◽  
Dissociation Process ◽  
Functional Theory ◽  
Classical Molecular Dynamics ◽  
Hydrogen Molecules

The dissociation process of hydrogen molecules on W(110) was studied using density functional theory and classical molecular dynamics.

Flexoelectricity in atomic monolayers from first principles

Nanoscale ◽  
2020 ◽  
Author(s):  
Shashikant Kumar ◽  
David Codony ◽  
Irene Arias ◽  
Phanish Suryanarayana
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Functional Theory ◽  
Group Iii ◽  
Flexoelectric Effect ◽  
Metal Dichalcogenides

We study the flexoelectric effect in fifty-four select atomic monolayers using ab initio Density Functional Theory (DFT). Specifically, considering representative materials from each of Group III monochalcogenides, transition metal dichalcogenides...

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