Calculations of cobalt silicide and carbide formation on SiC using the Gibbs free energy

Seng, William Francis; Barnes, P. A.

doi:10.1016/s0921-5107(00)00457-8

Cited by 22 publications

(6 citation statements)

References 27 publications

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“…Table provides data of a selected Gibbs free energy of formation for Co carburization, which points at some of the difficulties experienced in carburizing metallic Co because of the increasing free energy of Co 2 C with the drop in temperature. The Co 2 C decomposes to Co 0 with the hexagonal close packed (HCP) crystal structure and graphite, while Co 3 C decomposes to the Co 0 face‐centred cubic (FCC) structure and CH 4 .…”

Section: Discussionmentioning

confidence: 99%

Activation and deactivation scenarios in a plasma‐synthesized Co/C catalyst for Fischer‐Tropsch synthesis

Aluha

Abatzoglou

2018

Can J Chem Eng

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A carbon‐supported cobalt nano‐catalyst (Co/C) synthesized through plasma was tested for Fischer‐Tropsch activity. Catalyst deactivation and activation protocols studied included in situ sample pre‐treatment at 673 K in gas flowing at the rate of 250 cm3 · min−1 in: (a) H2 only, (b) CO only, and (c) CO followed by H2, with each cycle lasting 24 h. The so‐treated catalyst samples were then tested for FTS activity for over 50 h of time‐on‐stream (TOS), at 2.2 MPa pressure and 493 or 518 K temperature in a 3‐phase continuously‐stirred tank slurry reactor (3‐φ‐CSTSR) using squalane (C30H62) as the carrier liquid phase. The feed gas composition of molar H2:CO = 1.7 comprising 50 % H2, 30 % CO, and 10 % CO2 balanced in Ar for mass balance determination, flowing at a gas hourly space velocity (GHSV) of 3360 cm3 · h−1 · g−1 of catalyst. Fresh catalysts and those reduced by CO‐only were completely inactive at 493 K and initial inactivity was attributed to the excessive C matrix formed around the metal nanoparticles during catalyst synthesis. The sample that was reduced by H2 only was the most active, although it showed the fastest declining activity due to cumulative high H2O vapour pressure in the FTS reactor, while the sample pre‐treated in both CO and H2 demonstrated a higher degree of stability with TOS.

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Section: Discussionmentioning

confidence: 99%

Activation and deactivation scenarios in a plasma‐synthesized Co/C catalyst for Fischer‐Tropsch synthesis

Aluha

Abatzoglou

2018

Can J Chem Eng

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“…Gibbs free energy can be employed to examine the proclivity of spontaneity for any given chemical reaction (Seng and Barnes, 2000). The Gibbs free energy of reaction of CoSi 2 +C→CoSi+SiC is always negative in our experimental temperature ranges so that the reaction is thermodynamically favored.…”

Section: Resultsmentioning

confidence: 99%

“…The existence of SiC is a benefit for stabilizing CsCl-type CoSi, since only FeSi-type CoSi forms in Co/Si system. Seng and Barnes (2000) predicted isothermal ternary phase diagrams in the temperature ranges 25 to 270 °C and 270 to 1300 °C using the Gibbs free energy of formation in the Co–Si–C system. They also reported that Co 2 Si is in equilibrium with SiC and carbon at low temperatures, but it reacts with SiC to change to CoSi at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Chemical reactions in the Co–Si–C system

et al. 2008

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Isothermal sections at 1100 and 1500°C were determined by X-ray powder diffraction method to reveal stable phases and chemical pathways in the Co-Si-C system. There is no ternary compound present in either isothermal. Cobalt silicides are formed in the Co-rich region at temperatures lower than those in the Si-rich region. CoSi 2 reacts with carbon to form CoSi and SiC at 1500°C, and Co 2 Si and CoSi are more stable in equilibrium with carbon. The results are also discussed in terms of thermodynamics and binding energy of the reacting substances.

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“…The driving force of this adsorption process is likely to originate from the surface tension and excess surface Gibbs free energy at the molecular interface of MOFs . Owing to the high specific surface area of the MOF materials, the capture of the included gas molecules and liquid molecules is favored, which is the feature of porous materials with high adsorption capacity. − Importantly, the factors that affect the adsorption processes of mesoporous crystal MOF materials and nucleic acids with different secondary structures were discussed in terms of steric hindrance, entropy, and energy (Figure ), indicating that MOFs selectively include nucleic acids depending on their different sizes/shapes, lengths/molecular weights, and structural stability.…”

Section: Discussionmentioning

confidence: 99%

Efficient Separation of Nucleic Acids with Different Secondary Structures by Metal–Organic Frameworks

et al. 2020

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We report the use of metal–organic frameworks (MOFs) for the selective separation of nucleic acids (DNA and RNA) with different secondary structures through size, shape, length, and capability of conformational transition. Three MOFs with precisely controlled pore environments, Co-IRMOF-74-II, -III, and -IV, composed of Co2+ and organic linkers (II, III, and IV), respectively, were used for the inclusion of nucleic acid into their pores from the solution. This was proven to be a spontaneous process from disordered free state to restricted ordered state via circular dichroism (CD) spectroscopy. Three critical factors were identified for their inclusion: (1) size selection induced by steric hindrance, (2) conformation transition energy selection induced by stability, and (3) molecular weight selection. These selection rules were used to extract nucleic acids with flexible and unstable secondary structures from complex mixtures of multiple nucleic acids, leaving those with rigid and stable secondary structures in the mother liquor. This provides the possibility to separate and enrich nucleic acids in bulk through their different structure feature, which is highly desirable in genome-wide structural measurement of nucleic acids. Unlike methods that rely on specific binding antibodies or ligand, this MOF method is capable of selecting all kinds of nucleic acids with similar secondary structure features; therefore, it is suitable for the handling of a large variety and quantity of nucleic acids at the same time. This method also has the potential to gather information about the folding stability of biomolecules with secondary structures.

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Calculations of cobalt silicide and carbide formation on SiC using the Gibbs free energy

Cited by 22 publications

References 27 publications

Activation and deactivation scenarios in a plasma‐synthesized Co/C catalyst for Fischer‐Tropsch synthesis

Activation and deactivation scenarios in a plasma‐synthesized Co/C catalyst for Fischer‐Tropsch synthesis

Chemical reactions in the Co–Si–C system

Efficient Separation of Nucleic Acids with Different Secondary Structures by Metal–Organic Frameworks

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