Insight into CH x formation in Fischer–Tropsch synthesis on the hexahedron Co catalyst: Effect of surface structure on the preferential mechanism and existence form

Zhang, Riguang; Liu, Fu; Wang, Qiang; Wang, Baojun; Li, Debao

doi:10.1016/j.apcata.2016.07.007

Cited by 18 publications

(4 citation statements)

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“…The flat Co (0001) facet with four layers while the rest rugged facets with three closed packed (0001) atomic layers were considered to be reasonable based on the previous work. [37,38] All possible adsorption sites of Ru atom were tested to determine the most favorable adsorption configurations. During geometry optimization, the top two layers of cobalt atoms and the adsorbed Ru atoms were allowed to relax while the bottom layers were fixed at the bulk-optimized positions.…”

Section: Computational Methods and Models 21 Modelsmentioning

confidence: 99%

“…The variation of Ru surface coverage is achieved by adjusting the surface size from p (1×3) to p (6×4). The flat Co(0001) facet with four layers while the rest rugged facets with three closed packed (0001) atomic layers were considered to be reasonable based on the previous work . All possible adsorption sites of Ru atom were tested to determine the most favorable adsorption configurations.…”

Section: Computational Methods and Modelsmentioning

confidence: 99%

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Morphology Evolution of Hcp Cobalt Nanoparticles Induced by Ru Promoter

Liu

Qin

et al. 2020

ChemCatChem

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The modification of the equilibrium morphology to expose active facets of cobalt nanoparticles is essential for tailoring and controlling its catalytic performance. Periodic density functional theory (DFT) was applied to systematically investigate the structure and stability of exposed facets of hcp Co nanoparticles induced by Ru promoter in order to clarify the facet‐dependent equilibrium morphology of hcp Co nanoparticles stabilized by Ru promoter. The adsorption and migration of Ru atom can give rise to the change of the surface energy of exposed facets, thus affecting the equilibrium morphology of the hcp Co nanoparticles. Selectively exposed the high Miller index facets, such as Co(10‐12), Co(11‐20) and Co(11‐21) surfaces, can be tuned by adding Ru promoter. Our theoretical calculation results show that Co(11‐21) becomes the predominantly exposed facet accompanied with the decrease of exposed Co(10‐10) and Co(10‐11) with the increase of Ru loading. Further experimental studies suggest that the area of selectively exposed the Co(10‐11) surface for uniform Co nanoplates loaded with 3.0 wt % Ru will be reduced, which is in agreement with the theoretical predicted result. This work is helpful to design the desired Co‐based FTS catalysts rationally with well‐controlled surface structure.

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Section: Computational Methods and Models 21 Modelsmentioning

confidence: 99%

Section: Computational Methods and Modelsmentioning

confidence: 99%

Morphology Evolution of Hcp Cobalt Nanoparticles Induced by Ru Promoter

Liu

Qin

et al. 2020

ChemCatChem

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“…32 Hu et al 48 studied the adsorption and hydrogenation of CH x (x = 0−3) on the flat Co(0001) surface and showed that CH 3 hydrogenation was the rate-determining step in all of the CH x hydrogenation steps. Zhang et al 49 pointed out that the main form of CH x intermediates depends on the Co surface structure. Li et al 50 reported that structure selectivity with respect to chain growth and selectivity on HCP cobalt catalysts depends significantly on the exposed surfaces.…”

Section: Introductionmentioning

confidence: 99%

Rediscovering Tuning Product Selectivity by an Energy Descriptor: CH₄ Formation and C₁–C₁ Coupling on the FCC Co Surface

Liu

Wang

et al. 2020

J. Phys. Chem. C

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Despite extensive research work, how to control the chain growth by C 1 −C 1 coupling on the catalysts of Fischer− Tropsch synthesis (FTS) remains an unsolved problem. The activity, chain growth, and selectivity of FTS had been investigated on Co(111), ( 100), (311), and (110) surfaces with spin-polarized density functional theory (DFT) calculations. It is clearly shown that the CO activity decreases in the order of Co(110) > Co(311) > Co(100) > Co(111). Surface carbon is successively hydrogenated to CH 4 or undergoes chain growth to form heavier hydrocarbons. The effective barrier difference as a descriptor was introduced to evaluate the selectivity of CH 4 formation and C 1 −C 1 coupling. According to the effective barriers difference, the Co(100) surface has high selectivity toward C 1 −C 1 coupling, which is attributed to the active site containing two 4-fold hollow sites. The Co(110) surface has the highest selectivity of CH 4 formation. Moreover, it is revealed that the exposed specific cobalt crystal plane could tune the FTS selectivity to higher CO activity and lower CH 4 selectivity. This work highlights the effects of surfaces and active sites on catalytic selectivity and promotes the design of Co-based catalysts of FTS with high selectivity for long-chain hydrocarbons.

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“…Formyl (HCO) was experimentally identified as an intermediate of CO hydrogenation on a Ru(111) surface . Meanwhile, in DFT studies of the CO 2 hydrogenation process, HCO was also considered as an important intermediate. ,− This study found that HCO prefers to bind at 3-fold hollow sites with an O atom binding with two step edge Ni atoms. Hydroxymethylidyne (COH), another possible intermediate during the process of CO hydrogenation, − was found to prefer to bind at 3-fold hollow sites through the C atom with an adsorption energy of −5.09 eV.…”

Section: Resultsmentioning

confidence: 99%

Thermodynamic and Kinetic Study on Carbon Dioxide Hydrogenation to Methanol over a Ga₃Ni₅(111) Surface: The Effects of Step Edge

et al. 2018

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Density functional theory (DFT) was used to study the mechanisms of carbon dioxide (CO2) hydrogenation to methanol (CH3OH) on a stepped Ga3Ni5(111) surface. Surface properties, adsorption energies of reactants, and potential intermediates and products, as well as thermodynamic and kinetic parameters of elementary steps, were calculated. It is found that a stepped Ga3Ni5(111) surface with low surface energy not only can highly activate CO2 but also is beneficial to dissociative H2 adsorption. Moreover, the reactants, intermediates, and products on the Ga3Ni5(111) surface prefer to adsorb to Ni sites at step edges. Accoring to calculated thermodynamic and kinetic parameters of all the elementary steps, CO2 is hydrogenated to CH3OH via trans-COOH, COHOH, COH, HCOH, and CH2OH intermediates because this pathway has the lowest activation barriers and highest rate constants. Meanwhile, water (H2O) formation is the rate-limiting step. On the basis of microkinetic modeling, Ga3Ni5(111) shows higher selectivity to CH3OH than CH4. In all, the stepped Ga3Ni5(111) surface is beneficial in facilitating CO2 hydrogenation to CH3OH, and the presence of steps and the existence of Ga on those steps instead of step edge are required for the high activity of the Ga3Ni5 catalyst.

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Insight into CH x formation in Fischer–Tropsch synthesis on the hexahedron Co catalyst: Effect of surface structure on the preferential mechanism and existence form

Cited by 18 publications

References 45 publications

Morphology Evolution of Hcp Cobalt Nanoparticles Induced by Ru Promoter

Morphology Evolution of Hcp Cobalt Nanoparticles Induced by Ru Promoter

Rediscovering Tuning Product Selectivity by an Energy Descriptor: CH₄ Formation and C₁–C₁ Coupling on the FCC Co Surface

Thermodynamic and Kinetic Study on Carbon Dioxide Hydrogenation to Methanol over a Ga₃Ni₅(111) Surface: The Effects of Step Edge

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Insight into CH x formation in Fischer–Tropsch synthesis on the hexahedron Co catalyst: Effect of surface structure on the preferential mechanism and existence form

Cited by 18 publications

References 45 publications

Morphology Evolution of Hcp Cobalt Nanoparticles Induced by Ru Promoter

Morphology Evolution of Hcp Cobalt Nanoparticles Induced by Ru Promoter

Rediscovering Tuning Product Selectivity by an Energy Descriptor: CH4 Formation and C1–C1 Coupling on the FCC Co Surface

Thermodynamic and Kinetic Study on Carbon Dioxide Hydrogenation to Methanol over a Ga3Ni5(111) Surface: The Effects of Step Edge

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Product

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Rediscovering Tuning Product Selectivity by an Energy Descriptor: CH₄ Formation and C₁–C₁ Coupling on the FCC Co Surface

Thermodynamic and Kinetic Study on Carbon Dioxide Hydrogenation to Methanol over a Ga₃Ni₅(111) Surface: The Effects of Step Edge