Effect of boron promotion on the stability of cobalt Fischer–Tropsch catalysts

Tan, Kong Fei; Chang, Jie; Borgna, Armando; Saeys, Mark

doi:10.1016/j.jcat.2011.03.002

Cited by 67 publications

(89 citation statements)

References 51 publications

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“…13−15 The effect of boron on bulk Co and Ni catalysts has been well-documented. 16,17 B was also shown to impregnate surfaces and step-sites of Co and Ni, starting from octahedral or nearly square planar geometries. The formation of the surface alloy with square planar B is accompanied by the p4g surface reconstruction.…”

Section: Introductionmentioning

confidence: 99%

Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

2015

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Immobilized Pt clusters are interesting catalysts for dehydrogenation of alkanes. However, surface-deposited Pt clusters deactivate rapidly via sintering and coke deposition. The results reported here suggest that adding boron to oxide-supported Pt clusters could be a "magic bullet" against both means of deactivation. The model systems studied herein are pure and B-doped Pt clusters deposited on MgO(100). The nonstoichiometric boride cluster obtained via such alloying is found to anchor to the support via a covalent B−O bond, and the cluster-surface binding is much stronger than in the case of pure Pt clusters. Additionally, B introduces covalency to the intracluster bonding, leading to structural distortion and stabilization. The energy required to dissociate a Pt atom from a boride cluster is significantly larger than that of pure Pt clusters. These energetic arguments lead to the proposal that sintering via both Ostwald ripening and particle coalescence would be discouraged relative to pure Pt clusters. Finally, it is shown that the affinity to C also drops dramatically for borated clusters, discouraging coking and increasing the selectivity of potential cluster catalysts.

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Section: Introductionmentioning

confidence: 99%

Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

2015

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“…Secondly, in the calcinations stage, Cu(NO 3 ) 2 would first decompose to form CuO, then CuO reacts with B 2 O 3 to from copper borate, which will convert to well-dispersed nano Cu particles after H 2 reduction. B 2 O 3 is usually added to impart thermal stability of a catalyst [45]. Tan et al used CoB/Al 2 O 3 in Fischer-Tropsch synthesis (under conditions comparatively harsher than ours) and reported enhanced thermal stability of the catalyst owing to the presence of boron oxide at the surface sites of the catalyst [45].…”

Section: Influence Of B Incorporationmentioning

confidence: 71%

“…B 2 O 3 is usually added to impart thermal stability of a catalyst [45]. Tan et al used CoB/Al 2 O 3 in Fischer-Tropsch synthesis (under conditions comparatively harsher than ours) and reported enhanced thermal stability of the catalyst owing to the presence of boron oxide at the surface sites of the catalyst [45]. However, the mechanism of thermal stabilization of boron incorporated catalysts is not clear.…”

Section: Influence Of B Incorporationmentioning

confidence: 73%

“…However, the mechanism of thermal stabilization of boron incorporated catalysts is not clear. One possible explanation is owing to the strong interaction between Ni and B, and Co and B in Ni-B/SiO 2 and Co-B/MCM-41, respectively, leading to suppression of metal sintering and improvement in the dispersion of active species [38,45]. Yin et al reported that the incorporation of B 2 O 3 to Cu-based catalysts generated more active sites of Cu in dimethyl oxalate hydrogenation [46].…”

Section: Influence Of B Incorporationmentioning

confidence: 99%

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Selective Hydrogenolysis of Glycerol and Crude Glycerol (a By-Product or Waste Stream from the Biodiesel Industry) to 1,2-Propanediol over B2O3 Promoted Cu/Al2O3 Catalysts

et al. 2017

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Abstract:The performance of boron oxide (B 2 O 3 )-promoted Cu/Al 2 O 3 catalyst in the selective hydrogenolysis of glycerol and crude glycerol (a by-product or waste stream from the biodiesel industry) to produce 1,2-propanediol (1,2-PDO) was investigated. The catalysts were characterized using N 2 -adsorption-desorption isotherm, Inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), ammonia temperature programmed desorption (NH 3 -TPD), thermogravimetric analysis (TGA), temperature programmed reduction (TPR), and transmission electron microscopy (TEM). Incorporation of B 2 O 3 to Cu/Al 2 O 3 was found to enhance the catalytic activity. At the optimum condition (250 • C, 6 MPa H 2 pressure, 0.1 h −1 WHSV (weight hourly space velocity), and 5Cu-B/Al 2 O 3 catalyst), 10 wt% aqueous solution of glycerol was converted into 1,2-PDO at 98 ± 2% glycerol conversion and 98 ± 2% selectivity. The effects of temperature, pressure, boron addition amount, and liquid hourly space velocity were studied. Different grades of glycerol (pharmaceutical, technical, or crude glycerol) were used in the process to investigate the stability and resistance to deactivation of the selected 5Cu-B/Al 2 O 3 catalyst.

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“…However, depending on the method of preparation, surface borides can be made to promote the Co and Ni catalysts. [44,45] Carbides prefer the (near-)p4g structure:Csits slightly above the plane in d 8 systems and Ni, lies planar in d 10 systems,a nd goes subsurface in Pd. Ag 2 Ci st he only surface carbide to not reconstruct.…”

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confidence: 99%

Origin of Extraordinary Stability of Square‐Planar Carbon Atoms in Surface Carbides of Cobalt and Nickel

et al. 2015

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Surface carbides of cobalt and nickel are exceptionally stable, having stabilities competitive with those of graphitic C on these surfaces. The unusual structure of these carbides has attracted much attention: C assumes a tetracoordinate square‐planar arrangement, in‐plane with the metal surface, and its binding favors a spontaneous p4g clock surface reconstruction. A chemical bonding model for these systems is presented and explains the unusual structure, special stability, and the reconstruction. C promotes local two‐dimensional aromaticity on the surface and the aromatic arrangement is so powerful that the required number of electrons is taken from the void M4 squares, thus leading to Peierls instability. Moreover, this model predicts a series of new transition‐metal and main‐group‐element surface alloys: carbides, borides, and nitrides, which feature high stability, square‐planar coordination, aromaticity, and a predictable degree of surface reconstruction.

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Effect of boron promotion on the stability of cobalt Fischer–Tropsch catalysts

Cited by 67 publications

References 51 publications

Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

Alloying Pt Sub-nano-clusters with Boron: Sintering Preventative and Coke Antagonist?

Selective Hydrogenolysis of Glycerol and Crude Glycerol (a By-Product or Waste Stream from the Biodiesel Industry) to 1,2-Propanediol over B2O3 Promoted Cu/Al2O3 Catalysts

Origin of Extraordinary Stability of Square‐Planar Carbon Atoms in Surface Carbides of Cobalt and Nickel

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