scholarly journals Experimental and Density Functional Theory Studies on 1,1,1,4,4,4-Hexafluoro-2-Butene Pyrolysis

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3799
Author(s):  
Neng Tao ◽  
Changcheng Liu ◽  
Haoran Xing ◽  
Song Lu ◽  
Siuming Lo ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Thermal Decomposition ◽  
Density Functional ◽  
Decomposition Temperature ◽  
Thermal Decomposition Mechanism ◽  
Functional Theory ◽  
Production Of Hydrogen ◽  
Three Stages ◽  
Decomposition Experiments ◽  
Thermal Stability Of

A series of thermal decomposition experiments were conducted over a temperature range of 873–1073 K to evaluate the thermal stability of 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) and the production of hydrogen fluoride (HF). According to the detected products and experimental phenomena, the thermal decomposition of HFO-1336mzz(Z) could be divided into three stages. Our experimental results showed that HF concentration gradually increased with the elevation of thermal decomposition temperature. In this present study, a total of seven chemical reaction pathways of HFO-1336mzz(Z) pyrolysis were proposed to explore the generated mechanism on products through density functional theory (DFT) with M06-2X/6-311++(d,p) level theory. The thermal decomposition mechanism of pure HFO-1336mzz(Z) was discussed and the possible formation pathways of HF and other main products were proposed.

Thermal Decomposition of Hydroxylamine Nitrate Studied by Differential Scanning Calorimetry Analysis and Density Functional Theory Calculations

2017 ◽  
Vol 42 (4) ◽  
pp. 334-343
Author(s):  
Jianguo Liu ◽  
Zhentao An ◽  
Qian Zhang ◽  
Chaoyang Wang
Keyword(s):  
Activation Energy ◽  
Density Functional Theory ◽  
Differential Scanning Calorimetry ◽  
Thermal Decomposition ◽  
Density Functional ◽  
Probable Mechanism ◽  
Thermal Decomposition Mechanism ◽  
Scanning Calorimetry ◽  
Functional Theory ◽  
Mechanism Function

The thermal stability and kinetics of hydroxylamine nitrate (HAN) decomposition were studied by differential scanning calorimetry (DSC) and the thermal decomposition reaction mechanism was determined by density functional theory (DFT). With the help of parameter values from the non-isothermal DSC curves of HAN, the thermal decomposition activation energy and pre-exponential constant were obtained by the Kissinger and Ozawa methods. Then, the most probable mechanism function was calculated by the Šatava–Šesták method. Seven different paths for the thermal decomposition mechanism of HAN were formulated and DFT at the B3LYP/6-311++G(d,p) level was used to carry out the dynamics analysis. The calculated results show that the values of the activation energy calculated by the Kissinger and Ozawa methods are 67.892 and 70.412 kJ mol−1 respectively. The most probable mechanism function calculated by the Šatava–Šesták method is [Formula: see text]. The path being favoured energetically in the dynamics is in the order: Path6 > Path5 > Path4 > Path1 > Path2 > Path7 > Path3.

Investigation of mechanical properties and thermal stability of the thinnest tungsten nanowire by density functional theory

RSC Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 1158-1168 ◽  
Author(s):  
Hui-Lung Chen ◽  
Shin-Pon Ju ◽  
Ken-Huang Lin ◽  
Jia-Yun Li ◽  
Hsin-Tsung Chen
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Density Functional Theory ◽  
Simulated Annealing ◽  
Density Functional ◽  
Tight Binding ◽  
Functional Theory ◽  
Basin Hopping ◽  
Penalty Algorithm ◽  
Thermal Stability Of

The most stable structure of the thinnest tungsten (W) nanowire with the radius of 1.9 Å was predicted by the simulated annealing basin-hopping method (SABH) with the tight-binding (TB) potential and the penalty algorithm.

scholarly journals Density Functional Theory Study of Metal and Metal-Oxide Nucleation and Growth on the Anatase TiO2(101) Surface

Computation ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 125
Author(s):  
Leila Kalantari ◽  
Fabien Tran ◽  
Peter Blaha
Keyword(s):  
Density Functional Theory ◽  
Metal Oxide ◽  
Adsorption Energy ◽  
Density Functional ◽  
Magnetic Moments ◽  
Experimental Studies ◽  
Anatase Tio2 ◽  
Functional Theory ◽  
Transition Electron Microscopy ◽  
Production Of Hydrogen

Experimental studies have shown the possible production of hydrogen through photocatalytic water splitting using metal oxide (MOy) nanoparticles attached to an anatase TiO2 surface. In this work, we performed density functional theory (DFT) calculations to provide a detailed description of the stability and geometry of MxOy clusters M = Cu, Ni, Co, Fe and Mn, x = 1–5, and y = 0–5 on the anatase TiO2(101) surface. It is found that unsaturated 2-fold-coordinated O-sites may serve as nucleation centers for the growth of metal clusters. The formation energy of Ni-containing clusters on the anatase surface is larger than for other M clusters. In addition, the Nin adsorption energy increases with cluster size n, which makes the formation of bigger Ni clusters plausible as confirmed by transition electron microscopy images. Another particularity for Ni-containing clusters is that the adsorption energy per atom gets larger when the O-content is reduced, while for other M atoms it remains almost constant or, as for Mn, even decreases. This trend is in line with experimental results. Also provided is a discussion of the oxidation states of M5Oy clusters based on their magnetic moments and Bader charges and their possible reduction with oxygen depletion.

scholarly journals Competitive Adsorption of H2O and SO2 on Catalytic Platinum Surfaces: a Density Functional Theory Study

2021 ◽  
Vol 74 ◽  
Author(s):  
Marietjie J. Ungerer ◽  
David Santos-Carballal ◽  
Cornelia G.C.E. van Sittert ◽  
Nora H. de Leeuw
Keyword(s):  
Density Functional Theory ◽  
Adsorption Energy ◽  
Sulphur Dioxide ◽  
Density Functional ◽  
Competitive Adsorption ◽  
Hydrogen Adsorption ◽  
Surface Reactivity ◽  
Functional Theory ◽  
Sulphur Poisoning ◽  
Production Of Hydrogen

ABSTRACT Platinum has been widely used as the catalyst of choice for the production of hydrogen in the hybrid sulphur (HyS) cycle. In this cycle, water (H2O) and sulphur dioxide (SO2) react to form sulphuric acid and hydrogen. However, the surface reactivity of platinum towards H2O and SO2 is not yet fully understood, especially considering the competitive adsorption that may occur on the surface. In this study, we have carried out density functional theory calculations with long-range dispersion corrections [DFT-D3-(BJ)] to investigate the competitive effect of both H2O and SO2 on the Pt (001), (011) and (111) surfaces. Comparing the adsorption of a single H2O molecule on the various Pt surfaces, it was found that the lowest adsorption energy (Eads = -1.758 eV) was obtained for the dissociative adsorption of H2O on the (001) surface, followed by the molecular adsorption on the (011) surface (Eads = -0.699 eV) and (111) surface (Eads = -0.464 eV). For the molecular SO2 adsorption, the trend was similar, with the lowest adsorption energy (Eads = -2.471 eV) obtained on the (001) surface, followed by the (011) surface (Eads = -2.390 eV) and (111) surface (Eads = -1.852 eV). During competitive adsorption by H2O and SO2, the SO2 molecule will therefore preferentially adsorb onto the Pt surface. If the concentration of SO2 increases, self-reaction between two neighbouring SO2 molecules may occur, leading to the formation of sulphur monoxide (SO) and -trioxide (SO3) on the surface, which could lead to sulphur poisoning of the Pt catalytic surface. Keywords: Platinum, water, sulphur dioxide, hydrogen, adsorption, density functional theory.

scholarly journals Catalytic water dissociation by greigite Fe 3 S 4 surfaces: density functional theory study

2016 ◽  
Vol 472 (2188) ◽  
pp. 20160080 ◽  
Author(s):  
A. Roldan ◽  
N. H. de Leeuw
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Iron Sulfide ◽  
Density Functional Theory Calculations ◽  
Sulfide Mineral ◽  
Water Dissociation ◽  
Molecular Adsorption ◽  
Hydroxyl Groups ◽  
Functional Theory ◽  
Production Of Hydrogen

The iron sulfide mineral greigite, Fe 3 S 4 , has shown promising capability as a hydrogenating catalyst, in particular in the reduction of carbon dioxide to produce small organic molecules under mild conditions. We employed density functional theory calculations to investigate the {001},{011} and {111} surfaces of this iron thiospinel material, as well as the production of hydrogen ad-atoms from the dissociation of water molecules on the surfaces. We systematically analysed the adsorption geometries and the electronic structure of both bare and hydroxylated surfaces. The sulfide surfaces presented a higher flexibility than the isomorphic oxide magnetite, Fe 3 O 4 , allowing perpendicular movement of the cations above or below the top atomic sulfur layer. We considered both molecular and dissociative water adsorption processes, and have shown that molecular adsorption is the predominant state on these surfaces from both a thermodynamic and kinetic point of view. We considered a second molecule of water which stabilizes the system mainly by H-bonds, although the dissociation process remains thermodynamically unfavourable. We noted, however, synergistic adsorption effects on the Fe 3 S 4 {001} owing to the presence of hydroxyl groups. We concluded that, in contrast to Fe 3 O 4 , molecular adsorption of water is clearly preferred on greigite surfaces.

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