scholarly journals Study on syngas methanation mechanism over Ni4/MCM-41 catalyst based on density functional theory

2019 ◽  
Vol 44 (3) ◽  
pp. 222-233 ◽  
Author(s):  
Jiaying Zhang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Density Functional Theory Method ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Calculation Results ◽  
Direct Dissociation ◽  
Methanation Catalyst ◽  
Mcm 41

The density functional theory method is employed to systematically explore the mechanism of syngas methanation on the Ni4/MCM-41 catalyst surface. The calculation results show that the optimal pathway of CH4 formation is CO + H → CHO + H → CH2O + H → CH3O → CH3 + H → CH4 with the rate-determining step of CH3O direct dissociation. Because the activation energy for the direct dissociation of CH3O species is much lower than that for the CH3OH formation (198.6 vs 264.8 kJ mol−1), there is almost no by-product CH3OH that appeared in the products of the syngas methanation over the Ni4/MCM-41 catalyst. Compared with other conventional nickel-based methanation catalysts, Ni4/MCM-41 catalyst is an excellent methanation catalyst with high selectivity of CH4.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

DENSITY FUNCTIONAL THEORY STUDY ON THE MECHANISM OF TRIMETHYLAMINE-CATALYZED BAYLIS–HILLMAN REACTION

2010 ◽  
Vol 09 (supp01) ◽  
pp. 65-75 ◽  
Author(s):  
JING LI ◽  
WAN-YI JIANG
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Dft Method ◽  
Polarizable Continuum Model ◽  
Functional Theory ◽  
Reaction Barrier ◽  
Hydrogen Shift ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Polarizable Continuum

The trimethylamine-catalyzed Baylis–Hillman reaction of formaldehyde and vinylaldehyde has been studied with the density functional theory (DFT) method of B3LYP/6-31+G(d,p). In the gas phase, the reaction involves an amine–formaldehyde–vinylaldehyde trimolecular addition transition structure followed by rate-determining intramolecular 1,3-hydrogen shift. When a bulk solvent effect of water was considered with conductor-like polarizable continuum model (CPCM), the reaction was found to follow the sequence of Michael-addition of amine to vinylaldehyde (step 1), addition of formaldehyde (step 2), and 1,3-hydrogen shift (step 3), with the 1,3-hydrogen shift as rate-determining. The overall reaction barrier is significantly reduced. When a molecule of water is involved in the reaction, the 1,3-hydrogen shift is significantly promoted so that the rate-determining step becomes the C–C bond formation. The calculated overall reaction barrier is in agreement with experimental observations.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

Computational insights into the photophysical and electroluminescence properties of homoleptic fac-Ir(C^N)3 complexes employing different phenyl-derivative-featuring phenylimidazole-based ligands for promising phosphors in OLEDs

2016 ◽  
Vol 45 (7) ◽  
pp. 3034-3047 ◽  
Author(s):  
Jieqiong Li ◽  
Li Wang ◽  
Kenan Sun ◽  
Jinglai Zhang
Keyword(s):  
Density Functional Theory ◽  
Electronic Structures ◽  
Density Functional ◽  
Photophysical Properties ◽  
Density Functional Theory Method ◽  
Theory Method ◽  
Functional Theory ◽  
Phenyl Derivative ◽  
The Density Functional Theory

The electronic structures and photophysical properties of three homoleptic iridium(iii) complexes IrL3 with C^N ligands are investigated by means of the density functional theory method.

DECOMPOSITION OF SiH4 ON THE SA TYPE STEPPED Si(100) SURFACE

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1401-1407 ◽  
Author(s):  
ŞENAY KATIRCIOĞlu ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Reaction Path ◽  
Density Functional Theory Method ◽  
Dissociative Adsorption ◽  
Theory Method ◽  
Functional Theory ◽  
Initial Stage ◽  
The Density Functional Theory

The density functional theory method is used to explore the mechanism of dissociative adsorption of silane (SiH4) on the SA type stepped Si(100) surface. Two reaction paths are described that produce silyl (SiH3) and hydrogen atom fragments adsorbed on the dimer bonds present on each terrace. It has been found that the initial stage of the dissociation of SiH4 on the SA type stepped Si(100) surface shows similarity to the dissociation of SiH4 on the flat Si(100) surface; SiH3 and hydrogen fragments bond to the Si dimer atoms by following the first reaction path.

Sign in / Sign up

Export Citation Format

Share Document