Improving the coking resistance of Ni-based catalysts by promotion with subsurface boron

Xu, Jing; Saeys, Mark

doi:10.1016/j.jcat.2006.05.029

Cited by 115 publications

(130 citation statements)

References 31 publications

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“…A more recent theoretical study by Xu and Saeys using first-principles density functional theory calculations suggests that a small amount of boron corresponding to a single monolayer adsorption may be sufficient to reduce the coking of a Ni-based catalyst. [48] This is largely because boron prefers to adsorb in the octahedral sites of the first subsurface layer of the metal so that the boron atoms effectively block the subsurface sites and thus prevent carbon diffusion into the bulk of the metal. This effect assists in forcing carbon atoms to be available on the surface for reactions.…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Exploring the Structural Complexities of Metal–Metalloid Nanoparticles: The Case of Ni⋅B as Catalyst

Geng¹,

Jefferson²,

Johnson³

2009

Chemistry A European J

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Understanding of the structural complexities of metal-metalloid nanoparticles is at the heart of several proposals for investigating the physical properties and practical applications of these bi-elemental nanomaterials. To date, the most widely studied metal-metalloid is the nickel-boron (Ni.B) system; however, the exact nature of the structure of the material itself has remained unclear. Herein we show our systematic investigations of the material in an attempt to reveal its fascinating nanostructure. The relation between its high catalytic activity and the ultrafine structure is explored, and the work has been further extended to the formation of colloidal Ni.B nanoparticles. The results presented in this work may represent a substantial progress toward a full understanding of the nickel-boron chemistry.

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Section: Wwwchemeurjorgmentioning

confidence: 99%

Exploring the Structural Complexities of Metal–Metalloid Nanoparticles: The Case of Ni⋅B as Catalyst

Geng¹,

Jefferson²,

Johnson³

2009

Chemistry A European J

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“…Other non-metal elements, such as boron as an additive to nickel was also found to be an effective promoter to suppress surface coke formation [30]. It was suggested based on ab initio DFT calculations, that boron occupies the octahedral sites in the first subsurface layer of the nickel, which prevents carbon diffusion into the bulk of the nickel phase, thereby inhibiting the formation of carbon fibers [31]. Although post transition metals (Ga, Sn, In) are known promoters of supported noble metal catalysts, there is a lack of studies in the literature investigating the role of these metals on supported nickel catalysts in methane reforming reactions.…”

Section: Introductionmentioning

confidence: 99%

Carbon dioxide reforming of methane over Ni–In/SiO2 catalyst without coke formation

Károlyi

Németh

Evangelisti

et al. 2018

Journal of Industrial and Engineering Chemistry

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Keywords dry reforming of methane, silica supported nickel catalyst, nickel-indium bimetallic catalyst, coke formation, biogas conversion Highlights· Ni-In/SiO 2 catalysts were prepared by deposition-precipitation with urea. · Both metals were in metallic state after reduction at 700 °C. · Interaction of the two metals was evidenced by TPR, XPS. · The presence of indium in the close vicinity of nickel prevents coke formation. Graphical abstract AbstractThe development of a carbon tolerant nickel catalyst for carbon dioxide reforming of methane (dry reforming of methane, DRM) has been in the focus of catalysis research for several years.In the present study, 3wt%Ni/SiO 2 and bimetallic 3wt%Ni-2wt%In/SiO 2 catalysts (corresponding to 3:1 Ni:In ratio) were prepared by deposition precipitation with urea. Our intention was to modify the nickel surface with a second metal which is known from its ability to reduce surface coke formation. A methane rich reaction mixture (CH 4 :CO 2 :Ar = 2 69:30:1) was used for the catalytic tests at 600 °C and 675 °C. TPO measurements after the catalytic tests showed that there was no surface carbon formation on the indium containing catalyst.Temperature-programmed reduction measurements of the catalysts showed that both nickel and indium was completely reduced after one hour reduction at 700 °C suggesting interaction of the two metals. CO pulse chemisorption experiments revealed that the particle size was similar on the monometallic and bimetallic catalyst, and CO-TPD measurements showed completely different desorption behavior of CO, suggesting the presence of different active sites on the two catalysts. XPS experiments gave similar results, furthermore it was found that after reduction, the Ni/In ratio on the surface was 2.2 compared to the initial value (~3), which refers to the surface enrichment of indium in the bimetallic particles.The lack of coke formation on the indium containing catalyst might be explained by the interplay between a geometric and a chemical effect, that is, indium atoms are most likely situated on the edge and step sites of a nickel particle, influencing reactant adsorption and hindering the growth of carbon nanostructures and/or providing an oxygen rich indium suboxide surface through the reaction with CO 2 in the close vicinity of catalytically active nickel sites, which also inhibits the accumulation of carbon deposits during DRM.

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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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Improving the coking resistance of Ni-based catalysts by promotion with subsurface boron

Cited by 115 publications

References 31 publications

Exploring the Structural Complexities of Metal–Metalloid Nanoparticles: The Case of Ni⋅B as Catalyst

Exploring the Structural Complexities of Metal–Metalloid Nanoparticles: The Case of Ni⋅B as Catalyst

Carbon dioxide reforming of methane over Ni–In/SiO2 catalyst without coke formation

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

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