scholarly journals A DFT study of epoxidation of propylene on dimer MoO(x)

2021 ◽  
Author(s):  
Jiahui Peng ◽  
Zhehong Wan ◽  
Wei Chen ◽  
Hui Hu ◽  
Qingming Huang ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Density Functional ◽  
Main Product ◽  
Raw Material ◽  
Formation Processes ◽  
Fe Doping ◽  
Energy Barriers ◽  
Functional Theory ◽  
Epoxidation Of Propylene ◽  
Defect Sites

Propylene oxide is an important chemical raw material. In this paper, Density Functional Theory (DFT) was used to calculate the epoxidation of propylene on the dimer MoOx by Gaussian 09 software. Firstly, we established the structure of the dimer MoOx/SiO2 and analyzed it, and then calculated the dehydrogenation process of propylene and the formation process of PO. It was found that the activity of O in Mo-O-Si was higher, which was beneficial to the AHS process of C3H6, but the reaction activity of different O substances to the formation of PO was very low. In order to solve this problem, we established a dimer MoOx model with defect sites, and found that the defect sites in the dimer could effectively activate O2 (O2- 2), and the activated material O had high PO selectivity. Compared with process of AHS and the process of PO formation, the energy barrier of PO formation path was very low, which was the main product. At the same time, we also established the MoOx model of Fe doped dimer and the MoOx model of Fe doped defect dimer. It was found that the MoOx clusters were more active due to Fe doping, and the energy barriers of both AHS process and PO formation path were greatly reduced compared with those before doping. The presence of Fe made it easier for the dimer MoOx to form defect sites, which made it easier to activate O2 (O- 2) and reduced the energy barriers of both AHS and PO formation processes.

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

First principle simulation on oxidation mechanism of diethyl ether by nitrogen dioxide

2015 ◽  
Vol 14 (03) ◽  
pp. 1550020 ◽  
Author(s):  
Yuan Yuan ◽  
Wei Hu ◽  
Xuhui Chi ◽  
Cuihua Li ◽  
Dayong Gui ◽  
...  
Keyword(s):  
Diethyl Ether ◽  
Energy Barrier ◽  
Density Functional ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
High Energy ◽  
First Principle ◽  
Functional Theory ◽  
The Third ◽  
High Energy Barrier

The oxidation mechanism of diethyl ethers by NO2was carried out using density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The oxidation process of ether follows four steps. First, the diethyl ether reacts with NO2to produce HNO2and diethyl ether radical with an energy barrier of 20.62 kcal ⋅ mol-1. Then, the diethyl ether radical formed in the first step directly combines with NO2to form CH3CH ( ONO ) OCH2CH3. In the third step, the CH3CH ( ONO ) OCH2CH3was further decomposed into the CH3CH2ONO and CH3CHO with a moderately high energy barrier of 32.87 kcal ⋅ mol-1. Finally, the CH3CH2ONO continues to react with NO2to yield CH3CHO , HNO2and NO with an energy barrier of 28.13 kcal ⋅ mol-1. The calculated oxidation mechanism agrees well with Nishiguchi and Okamoto's experiment and proposal.

A DFT study on the mechanism of reaction between 2, 4-diisocyanatotolune and cellulose

2016 ◽  
Vol 15 (02) ◽  
pp. 1650012 ◽  
Author(s):  
Jiping Cao ◽  
Yali Liu ◽  
Aijuan Shi ◽  
Yuan Yuan ◽  
Mingliang Wang
Keyword(s):  
Reaction Mechanisms ◽  
Energy Barrier ◽  
Density Functional ◽  
Membered Ring ◽  
Functional Theory ◽  
Mechanism Of Reaction ◽  
The Density Functional Theory ◽  
Good Accordance ◽  
Experimental Activation Energy ◽  
Ring Transition State

The reaction mechanisms between 2, 4-Diisocyanatotolune (2, 4-TDI) and cellulose have been investigated using the density functional theory at the B3LYP/6-31[Formula: see text]G (d, p) level. The calculations show that the direct addition of 2, 4-TDI and cellulose possesses an unrealistically high barrier of 32–34[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. With a neighboring [Formula: see text]-d-glucose serving as a proton transporter by forming a flexible six-membered ring transition state, the energy barrier of the reaction is significantly reduced to 16–18 kcal[Formula: see text]mol[Formula: see text], which is in a good accordance with the experimental activation energy of 13.9–16.7[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is indicated that the reaction between 2, 4-TDI and cellulose is auto-catalyzed with a neighboring [Formula: see text]-d-glucose acting as a reactive catalyst.

Computational study on epoxidation of propylene by dioxygen using the silanol-functionalized polyoxometalate-supported osmium oxide catalyst

2019 ◽  
Vol 6 (12) ◽  
pp. 3482-3492 ◽  
Author(s):  
Yun-Jie Chu ◽  
Xue-Mei Chen ◽  
Chun-Guang Liu
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Oxide Catalyst ◽  
Computational Study ◽  
Density Functional Theory Calculations ◽  
Single Site ◽  
Functional Theory ◽  
Epoxidation Of Propylene ◽  
Osmium Oxide

The silanol-functionalized POM-supported single-site Os oxide catalyst has been theoretically considered for epoxidation of propylene in the presence of dioxygen based on density functional theory calculations.

scholarly journals Theoretical Study on Influence of Cobalt Oxides Valence State Change for C6H5COOH Pyrolysis

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 197
Author(s):  
Si-Mei Fu ◽  
Yue Zhao ◽  
Jiang-Tao Liu ◽  
Wen-Sheng Liang ◽  
Gang-Sen Li ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Valence State ◽  
Energy Barrier ◽  
Density Functional ◽  
Model Compound ◽  
Theoretical Study ◽  
Cobalt Oxides ◽  
State Change ◽  
Pyrolysis Process ◽  
Functional Theory

Benzoic acid (C6H5COOH) is selected as coal-based model compound with Co compounds (Co3O4, CoO and Co) as the catalysts, and the influence of the valence state change of the catalyst for pyrolysis process is investigated using density functional theory (DFT). DFT results shows that the highest energy barrier of C6H5COOH pyrolysis is in the following order: Ea(CoO) <Ea(Co3O4) <Ea(no catalyst) <Ea(Co). In general, Co3O4 catalyst accelerates C6H5COOH pyrolysis. Then, the catalytic activity further increases when Co3O4 is reduced to CoO. Finally, Co shows no activity for C6H5COOH pyrolysis due to the reduction of CoO to metallic Co.

THEORETICAL STUDIES ON THE REACTION MECHANISM OF HNCS WITH CH2CH RADICAL

2007 ◽  
Vol 06 (01) ◽  
pp. 1-12 ◽  
Author(s):  
JIAN-HUA XU ◽  
LAI-CAI LI ◽  
YAN ZHENG ◽  
JUN-LING LIU ◽  
XIN WANG
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Reaction Mechanisms ◽  
Density Functional ◽  
Hydrogen Transfer ◽  
Main Product ◽  
Reaction Pathways ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Ch Radical

The reaction mechanisms of HNCS with CH 2 CH radical have been investigated by density functional theory (DFT). The geometries and harmonic frequencies of the reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G(d,p) level. The results show that the reaction is very complicated. Nine possible reaction pathways were identified. The results show that the most feasible reaction channel is the hydrogen-transfer pathway CH 2 CH + HNCS → IMA1 → TSA1 → CH 2 CHH + NCS . The pathway VIC C-S addition channel ( CH 2 CH + HNCS → TSD5 → IMD4 → TSD9 → CH 2 CHS + CNH ) can also occur easily. Ethene and radical NCS is the main product of the studied reaction, and product P8 ( CH 2 CHS and CNH ) may also be observed. Compared with our previous study on the reaction HNCS + CH 2 CH , the present reaction is easier to proceed.

scholarly journals CO oxidation catalysed by Pd-based bimetallic nanoalloys

2015 ◽  
Vol 17 (42) ◽  
pp. 28010-28021 ◽  
Author(s):  
Dennis Palagin ◽  
Jonathan P. K. Doye
Keyword(s):  
Density Functional Theory ◽  
Co Oxidation ◽  
Oxidation Reaction ◽  
Density Functional ◽  
Geometry Optimization ◽  
Energy Barriers ◽  
Functional Theory ◽  
Global Geometry ◽  
Co Oxidation Reaction

Density functional theory based global geometry optimization has been used to demonstrate the crucial influence of the geometry of the catalytic cluster on the energy barriers for the CO oxidation reaction over Pd-based bimetallic nanoalloys.

scholarly journals Density functional theory study on the electronic properties and stability of silicene/silicane nanoribbons

2015 ◽  
Vol 3 (16) ◽  
pp. 3954-3959 ◽  
Author(s):  
Q. G. Jiang ◽  
J. F. Zhang ◽  
Z. M. Ao ◽  
Y. P. Wu
Keyword(s):  
Density Functional Theory ◽  
Electronic Properties ◽  
Density Functional ◽  
Minimum Energy ◽  
Density Functional Theory Study ◽  
Hydrogen Atoms ◽  
Energy Barriers ◽  
Functional Theory ◽  
Diffusion Of Hydrogen

The minimum energy barriers for the diffusion of hydrogen atoms at the zigzag and armchair interfaces of SSNRs are respectively 1.54 and 1.47 eV.

The Effect of N Vacancy on GaN Doped by Fe

2012 ◽  
Vol 463-464 ◽  
pp. 560-564
Author(s):  
Yu Feng Wang ◽  
Chong Yang ◽  
Ting Ting Guo
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Ground State ◽  
Density Functional ◽  
Fe Doping ◽  
Functional Theory

Using general graduated approximation (GGA) of the ab-initio based on density functional theory (DFT), three models of possible double Fe doping GaN and three models of possible N vacancy and double Fe codoping GaN were calculated. The results show that in the three models of double Fe doping GaN, the energies of antiferromagnetism (AFM) are lower than the ones of ferromagnetism (FM), which shows that the ground state of Fe doping GaN will be AFM, this agrees on the conclusion of literature [15]. After adding vacancies 2 and 3 respectively, we found a ferrimagnetic (FIM) ground state. But after adding vacancy 1, the ground state was still AFM.

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