Suppression by Pt of CO adsorption and dissociation and methane formation on Fe5C2(100) surfaces

To understand the chemical origin of platinum promotion effects on iron based Fischer–Tropsch synthesis catalysts, the effects of Pt on CO adsorption and dissociation as well as surface carbon hydrogenation on the Fe5C2(100) facet with different surface C* contents have been studied using the spin-polarized density functional theory method.

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A DFT investigation of the mechanisms of CO2 and CO methanation on Fe (111)

Materials for Renewable and Sustainable Energy ◽

10.1007/s40243-020-0164-x ◽

2020 ◽

Vol 9 (1) ◽

Author(s):

Caroline R. Kwawu ◽

Albert Aniagyei ◽

Richard Tia ◽

Evans Adei

Keyword(s):

Density Functional ◽

Density Functional Theory Calculations ◽

Environmentally Benign ◽

Methane Formation ◽

Functional Theory ◽

Co Methanation ◽

Detailed Mechanism ◽

Catalytic Surfaces ◽

Methanol Formation ◽

Spin Polarized

AbstractInsight into the detailed mechanism of the Sabatier reaction on iron is essential for the design of cheap, environmentally benign, efficient and selective catalytic surfaces for CO2 reduction. Earlier attempts to unravel the mechanism of CO2 reduction on pure metals including inexpensive metals focused on Ni and Cu; however, the detailed mechanism of CO2 reduction on iron is not yet known. We have, thus, explored with spin-polarized density functional theory calculations the relative stabilities of intermediates and kinetic barriers associated with methanation of CO2 via the CO and non-CO pathways on the Fe (111) surface. Through the non-CO (formate) pathway, a dihydride CO2 species (H2CO2), which decomposes to aldehyde (CHO), is further hydrogenated into methoxy, methanol and then methane. Through the CO pathway, it is observed that the CO species formed from dihydroxycarbene is not favorably decomposed into carbide (both thermodynamically and kinetically challenging) but CO undergoes associative hydrogenation to form CH2OH which decomposes into CH2, leading to methane formation. Our results show that the transformation of CO2 to methane proceeds via the CO pathway, since the barriers leading to alkoxy transformation into methane are high via the non-CO pathway. Methanol formation is more favored via the non-CO pathway. Iron (111) shows selectivity towards CO methanation over CO2 methanation due to differences in the rate-determining steps, i.e., 91.6 kJ mol−1 and 146.2 kJ mol−1, respectively.

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Mechanism of coverage dependent CO adsorption and dissociation on the Mo(100) surface

Physical Chemistry Chemical Physics ◽

10.1039/c6cp08129k ◽

2017 ◽

Vol 19 (3) ◽

pp. 2186-2192 ◽

Cited By ~ 7

Author(s):

Xinxin Tian ◽

Tao Wang ◽

Haijun Jiao

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Co Adsorption ◽

Functional Theory ◽

Adsorption And Dissociation

The mechanism of coverage dependent CO adsorption and dissociation on the Mo(100) surface was investigated using periodic density functional theory.

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Mechanistic Insight into H2S Adsorption and Dissociation on MoP(010): A Density Functional Investigation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1142.300 ◽

2017 ◽

Vol 1142 ◽

pp. 300-305

Author(s):

Gui Xia Li ◽

Hou Yu Zhu ◽

Lian Ming Zhao ◽

Wen Yue Guo ◽

Xiao Qing Lu ◽

...

Keyword(s):

Density Functional ◽

Co Adsorption ◽

Adsorbed Species ◽

Functional Theory ◽

Mechanistic Insight ◽

Structure Sensitive ◽

Bond Scission ◽

Functional Investigation ◽

Adsorption And Dissociation ◽

Insight Into

H2S adsorption and dissociation on MoP(010) were investigated using density functional theory (DFT) together with periodic slab models. Several different possibilities for H2S, SH, S and H adsorption were considered. Our results show that the H2S, SH and H prefer to adsorb at bridge site, while S adsorbs preferentially at hcp and bridge sites. Additionally, the optimum co-adsorption configurations for SH/H and S/H were determined. The results indicate that the co-adsorbed species repel each other slightly on MoP(010) surface. Finally, the potential energy profile of H2S dissociation on MoP(010) surface was given out. The dissociation energy barriers of the S–H bond scission exhibit that H2S prefers to dissociate on MoP(010) surface. When compared with MoP(001) surface, the obvious differences in H2S decomposition arise demonstrate that the MoP-based catalysts are structure-sensitive.

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Hägg carbide surfaces induced Pt morphological changes: a theoretical insight

Catalysis Science & Technology ◽

10.1039/c6cy00764c ◽

2016 ◽

Vol 6 (17) ◽

pp. 6726-6738 ◽

Cited By ~ 4

Author(s):

Yurong He ◽

Peng Zhao ◽

Wenping Guo ◽

Yong Yang ◽

Chun-Fang Huo ◽

...

Keyword(s):

Density Functional Theory ◽

Ab Initio ◽

Density Functional ◽

Morphological Changes ◽

Fischer Tropsch ◽

Functional Theory ◽

Diffusion Behavior ◽

Spin Polarized ◽

And Diffusion ◽

Theoretical Insight

Comprehensive spin-polarized density functional theory (DFT) combined with ab initio molecular dynamic (AIMD) simulations have been performed to explore the structures, energies, and diffusion behavior of platinum on Fe5C2 surfaces with importance in Fischer–Tropsch (F–T) catalysis.

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Density Functional Theory Study of CO Adsorption and Dissociation on Molybdenum(100)

The Journal of Physical Chemistry C ◽

10.1021/jp072673a ◽

2007 ◽

Vol 111 (36) ◽

pp. 13473-13480 ◽

Cited By ~ 14

Author(s):

Freek J. E. Scheijen ◽

J. W. (Hans) Niemantsverdriet ◽

Daniel Curulla Ferré

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Co Adsorption ◽

Density Functional Theory Study ◽

Functional Theory ◽

Adsorption And Dissociation

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Theoretical Study of CO Adsorption and Activation on Orthorhombic Fe7C3(001) Surfaces for Fischer–Tropsch Synthesis Using Density Functional Theory Calculations

Energies ◽

10.3390/en14030563 ◽

2021 ◽

Vol 14 (3) ◽

pp. 563

Author(s):

Hee-Joon Chun ◽

Yong Tae Kim

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Co Adsorption ◽

Density Functional Theory Calculations ◽

Tropsch Synthesis ◽

Fischer Tropsch ◽

Functional Theory ◽

Fischer Tropsch Synthesis ◽

Co Dissociation ◽

Co Activation

Fischer–Tropsch synthesis (FTS), which converts CO and H2 into useful hydrocarbon products, has attracted considerable attention as an efficient method to replace crude oil resources. Fe-based catalysts are mainly used in industrial FTS, and Fe7C3 is a common carbide phase in the FTS reaction. However, the intrinsic catalytic properties of Fe7C3 are theoretically unknown. Therefore, as a first attempt to understand the FTS reaction on Fe7C3, direct CO* dissociation on orthorhombic Fe7C3(001) (o-Fe7C3(001)) surfaces was studied using density functional theory (DFT) calculations. The surface energies of 14 terminations of o-Fe7C3(001) were first compared, and the results showed that (001)0.20 was the most thermodynamically stable termination. Furthermore, to understand the effect of the surface C atom coverage on CO* activation, C–O bond dissociation was performed on the o-Fe7C3(001)0.85, (001)0.13, (001)0.20, (001)0.09, and (001)0.99 surfaces, where the surface C atom coverages were 0.00, 0.17, 0.33, 0.33, and 0.60, respectively. The results showed that the CO* activation linearly decreased as the surface C atom coverage increased. Therefore, it can be concluded that the thermodynamic and kinetic selectivity toward direct CO* dissociation increased when the o-Fe7C3(001) surface had more C* vacancies.

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First-Principles Investigation of CO Adsorption on h-Fe7C3 Catalyst

Crystals ◽

10.3390/cryst10080635 ◽

2020 ◽

Vol 10 (8) ◽

pp. 635

Author(s):

Jinzhe Fu ◽

Deshuai Sun ◽

Zhaojun Chen ◽

Jian Zhang ◽

Hui Du

Keyword(s):

Adsorption Energy ◽

First Principles ◽

Density Functional ◽

Co Adsorption ◽

Active Phase ◽

Crystal Plane ◽

Fischer Tropsch ◽

Medium Temperature ◽

Functional Theory ◽

Miller Index

h-Fe7C3 is considered as the main active phase of medium-temperature Fe-based Fischer–Tropsch catalysts. Basic theoretical guidance for the design and preparation of Fe-based Fischer–Tropsch catalysts can be obtained by studying the adsorption and activation behavior of CO on h-Fe7C3. In this paper, the first-principles method based on density functional theory is used to study the crystal structure properties of h-Fe7C3 and the adsorption and activation CO on its low Miller index surfaces ( 1 1 ¯ 0 ) , ( 1 1 ¯ 1 ) , ( 101 ) , ( 1 1 ¯ 1 ¯ ) and ( 001 ) . It was found that the low Miller index crystal plane of h-Fe7C3 crystal has multiple equivalent crystal planes and that the maximum adsorption energy of CO at the 3F2 point of the ( 1 1 ¯ 1 ) plane is −2.50 eV, indicating that h-Fe7C3 has a better CO adsorption performance. In addition, the defects generated at the truncated position of the h-Fe7C3 crystal plane have a great impact on the adsorption energy of CO on its surface, that is, the adsorption energy of CO on Fe atoms with C vacancies is higher. The activity of CO after adsorption is greatly affected by the adsorption configuration and less affected by the adsorption energy. The higher the coordination number of Fe atoms after adsorption, the higher the CO activity. At the same time, it was found that the bonding of O and Fe atoms is conducive to the activation of CO.

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