Kinetic and Magnetic Studies on Supported Nickel Oxide Catalysts

Rymer, G.T.; Bridges, Joanne M.; Tomlinson, J. R.

doi:10.1021/j100829a009

Cited by 17 publications

(3 citation statements)

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“…1, 4,5 Unfortunately, the latter is difficult to reduce to the metallic statesonly at temperatures at which nickel sintering occurss and they are poorly active in oxidation and hydrogenation processes. 6,7 For catalysts with a low nickel loading (e2 Ni wt %), the distribution of nickel ions between octahedral and tetrahedral sites of alumina depends on several preparation parameters: support hydration, calcination atmosphere, and temperature 4,5,[8][9][10][11][12] or use of additives such as Na, Zn, Ge, or Ga, 13,14 but for all cases, the problem of low reducibility remains. Incipient wetness impregnation is the most common method to prepare catalysts and consists of filling the void volume of alumina with a solution of nickel salt.…”

Section: Introductionmentioning

confidence: 99%

“…A common way to obtain these phases is via deposition of nickel(II) nitrate on alumina, followed by a single thermal treatment in O 2 , or by successive treatments in O 2 and H 2 , respectively. A major problem encountered during calcination in O 2 is the migration of nickel ions into alumina to form nickel aluminate. ,, Unfortunately, the latter is difficult to reduce to the metallic stateonly at temperatures at which nickel sintering occursand they are poorly active in oxidation and hydrogenation processes. , For catalysts with a low nickel loading (≤2 Ni wt %), the distribution of nickel ions between octahedral and tetrahedral sites of alumina depends on several preparation parameters: support hydration, calcination atmosphere, and temperature ,,− or use of additives such as Na, Zn, Ge, or Ga, , but for all cases, the problem of low reducibility remains.…”

Section: Introductionmentioning

confidence: 99%

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A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al₂O₃-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

Négrier¹,

Marceau²,

Che³

et al. 2005

J. Phys. Chem. B

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1.5 Ni wt %/Al2O3 catalysts have been prepared by incipient wetness impregnation using [Ni(diamine)x(H2O)(6-2x)]Y2 precursors (diamine = 1,2-ethanediamine (en) and trans-1,2-cyclohexanediamine (tc); x = 0, 1, and 2; Y = NO3- and Cl-), to avoid the formation, during calcination, of difficult-to-reduce nickel aluminate. N2 was chosen for thermal treatment to help reveal and take advantage of the reactions occurring between Ni2+, ligands, counterions, and support. In the case of [Ni(en)2(H2O)2]Y2 salts used as precursors, in situ UV-vis and DRIFT spectroscopies show that after treatment at 230 degrees C Ni(II) ions are grafted to alumina via two OAl bonds and that the diamine ligands still remain coordinated to grafted nickel ions but in a monodentate way, bridging the cation with the alumina surface. With Y = Cl-, the chloride counterions desorb as hydrogen chloride, and hydrogen released upon decomposition of the en ligands is able to reduce a fraction of nickel ions into metal as evidenced by XPS. In contrast, with Y = NO3-, compounds such as CO or NO are formed during thermal treatment, indicating that nitrate ions burn the en ligands. After thermal treatment at 500 degrees C, a surface phase containing Ni(II) ions forms, characterized by XPS and UV-vis spectroscopy. Temperature-programmed reduction shows that these ions can be quantitatively reduced to the metallic state at 500 degrees C, in contrast with the aluminate obtained when the preparation is carried out from [Ni(H2O)6]2+, which is reduced only partly at 950 degrees C. On the other hand, a total self-reduction of nickel complexes leading to 2-5-nm metal particles is obtained upon thermal treatment via the hydrogen released by a hydrogen-rich ligand such as tc, whatever the Y counterion. An appropriate choice of the ligand and the counterion allows then to obtain selectively Ni(II) ions or a dispersed reduced nickel phase after treatment in N2, as a result of the reactions occurring between the chemical partners present on alumina.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al₂O₃-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

Négrier¹,

Marceau²,

Che³

et al. 2005

J. Phys. Chem. B

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“…Supported elemental nickel and nickel oxide catalysts on alumina have wide applications in important reactions, e.g., Ni/Al 2 O 3 for methanation, hydrogenation, and hydrocracking, − and NiO/Al 2 O 3 for CO oxidation and N 2 O decomposition . In the past few decades, a flurry of effort has been directed toward the preparation of nanosized nickel and its oxide particles with a high degree of dispersion on alumina due to the fact that usually a fine, highly dispersed nickel phase can provide more active sites which are accessible to reactant molecules and available for catalysis .…”

Section: Introductionmentioning

confidence: 99%

Sonochemical Coating of Nanosized Nickel on Alumina Submicrospheres and the Interaction between the Nickel and Nickel Oxide with the Substrate

et al. 1999

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The preparation and coating of nickel on amorphous and crystallized alumina were carried out by employing a sonochemical method. The interaction between the nickel as well as its oxide and the alumina core was then studied by TEM, XRD, DSC, DRS, FTIR, and magnetization measurements. The following were found: (1) Amorphous alumina can provide a great number of active sites for reaction with nickel and can yield a good coating effect in which most of nickel is adhered to the alumina surface tightly, while in the case of the crystallized alumina as substrate, most of nickel particles is distributed in the free space among the alumina submicrospheres.(2) As compared to the unadhered nickel, the adhered nickel has a strong interaction with the alumina core, which can retard the crystallization of elemental nickel and, conversely, promote the formation of the spinel phase NiAl 2 O 4 . (3) The first stage of the interaction between the nickel and the alumina may be through the isolated hydroxyl groups to form a kind of interface Ni-O-Al bond. The connection positions further become nucleation centers for elemental nickel. After the sample is heated to high temperatures, DRS and IR results showed the diffusion of nickel ions into the vacant tetrahedral sites in alumina. At higher temperature, an inversion processsthe substitution of Ni 2+ ions for part of Al 3+ at octahedral sites has taken place, and it results in the final formation of the disordered spinel phase. (4) Magnetization measurements show that the as-prepared sonication products are superparamagnetic due to the ultrafine nature of nickel particles.

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Surface structure and NiO dispersion for NiO/γ‐Al₂O₃ catalysts

Gambaro

Fierro

Tejuca

et al. 1982

Surface & Interface Analysis

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Chemisorption of CO at temperatures below 100 "C has been used to evaluate the dispersion of NiO in a series of NiO/y-AI2O3 catalysts. CO adsorption measurements were supplemented by i.r. spectroscopy to establish the CO/NiO stoichiometry. From monolayer coverage data derived from Freundlich's equation, the percentage of NiO dispersion and the average NiO crystallite size were calculated. The crystallite size of supported NiO was found to be practically constant for NiO loadings from 1 to 8 wt%, experimenting an abrupt increase for higher NiO contents. These results were consistent with additional information on the surface structure of the catalysts obtained by IR spectroscopy, X-ray diffraction, magnetic susceptibility, and reduction with Hz.

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Kinetic and Magnetic Studies on Supported Nickel Oxide Catalysts

Cited by 17 publications

References 1 publication

A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al₂O₃-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al₂O₃-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

Sonochemical Coating of Nanosized Nickel on Alumina Submicrospheres and the Interaction between the Nickel and Nickel Oxide with the Substrate

Surface structure and NiO dispersion for NiO/γ‐Al₂O₃ catalysts

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Kinetic and Magnetic Studies on Supported Nickel Oxide Catalysts

Cited by 17 publications

References 1 publication

A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al2O3-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al2O3-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

Sonochemical Coating of Nanosized Nickel on Alumina Submicrospheres and the Interaction between the Nickel and Nickel Oxide with the Substrate

Surface structure and NiO dispersion for NiO/γ‐Al2O3 catalysts

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A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al₂O₃-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

A Systematic Study of the Interactions between Chemical Partners (Metal, Ligands, Counterions, and Support) Involved in the Design of Al₂O₃-Supported Nickel Catalysts from Diamine−Ni(II) Chelates

Surface structure and NiO dispersion for NiO/γ‐Al₂O₃ catalysts