Synthesis, characterisation and performance evaluation of spinel-derived Ni/Al2O3 catalysts for various methane reforming reactions

Boukha, Zouhair; Jiménez‐González, Cristina; Rivas, Beatriz de; González‐Velasco, Juan R.; Gutiérrez-Ortiz, José I.; López‐Fonseca, Rubén

doi:10.1016/j.apcatb.2014.04.014

Cited by 141 publications

(93 citation statements)

References 46 publications

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“…Briefly, Ni 2+ (Oh) species are A magnification of the UV-Vis-DRS spectra in the visible region (350-800 nm) of the mentioned samples can be seen in Figure 7. The signals in this region represent d-d transitions of Ni 2+ ions mainly in octahedral (O h ) and tetrahedral coordination (T d ) [43]. Pure NiO presents intense signals at 380, 420, and 720 nm which illustrate the Ni 2+ (O h ) in the cubic (rock-salt) NiO lattice [44].…”

Section: Characterization Of the Catalystsmentioning

confidence: 99%

Development of Active and Stable Low Nickel Content Catalysts for Dry Reforming of Methane

Armbruster

Atia

et al. 2017

Catalysts

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Methane dry reforming (DRM) was investigated over highly active Ni catalysts with low metal content (2.5 wt %) supported on Mg-Al mixed oxide. The aim was to minimize carbon deposition and metal sites agglomeration on the working catalyst which are known to cause catalyst deactivation. The solids were characterized using N 2 adsorption, X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that MgO-Al 2 O 3 solid solution phases are obtained when calcining Mg-Al hydrotalcite precursor in the temperature range of 550-800 • C. Such phases contribute to the high activity of catalysts with low Ni content even at low temperature (500 • C). Modifying the catalyst preparation with citric acid significantly slows the coking rate and reduces the size of large octahedrally coordinated NiO-like domains, which may easily agglomerate on the surface during DRM. The most effective Ni catalyst shows a stable DRM course over 60 h at high weight hourly space velocity with very low coke deposition. This is a promising result for considering such catalyst systems for further development of an industrial DRM technology.

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Section: Characterization Of the Catalystsmentioning

confidence: 99%

Development of Active and Stable Low Nickel Content Catalysts for Dry Reforming of Methane

Armbruster

Atia

et al. 2017

Catalysts

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“…This doublet is assigned to Ni 2+ ions in tetrahedral symmetry and thus it is associated with the formation of the NiAl 2 O 4 phase detected by XRD. Two shoulders appearing at 561 and 715 nm are assigned to Ni 2+ ions in octahedral symmetry associated with the NiO phase [27,28]. To study the effect of doping on the catalysts, it is necessary to analyze the peaks of various Ni 2+ species.…”

Section: Physicochemical Characteristics Of the Ni-catalystsmentioning

confidence: 99%

Ni Catalysts Supported on Modified Alumina for Diesel Steam Reforming

et al. 2016

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Nickel catalysts are the most popular for steam reforming, however, they have a number of drawbacks, such as high propensity toward coke formation and intolerance to sulfur. In an effort to improve their behavior, a series of Ni-catalysts supported on pure and La-, Ba-, (La+Ba)-and Ce-doped γ-alumina has been prepared. The doped supports and the catalysts have been extensively characterized. The catalysts performance was evaluated for steam reforming of n-hexadecane pure or doped with dibenzothiophene as surrogate for sulphur-free or commercial diesel, respectively. The undoped catalyst lost its activity after 1.5 h on stream. Doping of the support with La improved the initial catalyst activity. However, this catalyst was completely deactivated after 2 h on stream. Doping with Ba or La+Ba improved the stability of the catalysts. This improvement is attributed to the increase of the dispersion of the nickel phase, the decrease of the support acidity and the increase of Ni-phase reducibility. The best catalyst of the series doped with La+Ba proved to be sulphur tolerant and stable for more than 160 h on stream. Doping of the support with Ce also improved the catalytic performance of the corresponding catalyst, but more work is needed to explain this behavior.

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“…This catalyst enabled a CNF yield of 20 g CNF g cat -1 after 2 h of reaction. However, the difficulties associated with the thermal instability of Al 2 O 3 and its low mechanical strength have been reported by Boukha et al [25]. Moreover, alumina can create spinels with nickel, which prevents the formation of nickel growth centers [25].…”

Section: Kinetics Of Cnf Growthmentioning

confidence: 99%

“…The chemical inertness of HAp is an important property for a material that will be used as a catalyst support. HAp does not exhibit any catalytic activity during the high-temperature treatment [20] or create spinels that would lead to a reduction in the catalyst reducibility, which is often observed for alumina-supported nickel catalysts [24,25]. Therefore, HAp appears to be a good support for Ni catalysts for the synthesis of CNF using CCVD.…”

Section: Introductionmentioning

confidence: 99%

“…However, the difficulties associated with the thermal instability of Al 2 O 3 and its low mechanical strength have been reported by Boukha et al [25]. Moreover, alumina can create spinels with nickel, which prevents the formation of nickel growth centers [25]. Based on these negative features, alumina can be replaced by other promising Ni catalyst supports, such as the studied hydroxyapatite, which has excellent mechanical properties and does not react with nickel.…”

Section: Kinetics Of Cnf Growthmentioning

confidence: 99%

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Growth of carbon nanofibers from methane on a hydroxyapatite-supported nickel catalyst

et al. 2016

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Carbon nanofibers (CNFs) were grown using catalytic chemical vapor deposition (CCVD) with methane as the carbon source and a hydroxyapatite-supported nickel catalyst (Ni/HAp). The catalyst, which contained approximately 14 wt% Ni, was prepared using the incipient wetness method with an aqueous nickel nitrate solution. Temperature-programmed reduction and X-ray diffraction were used to characterize the active phase of Ni/HAp. Three variables were evaluated to optimize the CNF growth process, including the temperature and the time of catalyst reduction as well as the reaction time, at 650°C. Regardless of the applied CCVD process conditions, herringbone bamboo-like CNFs were grown during methane decomposition over Ni/HAp, which was confirmed using transmission electron microscopy. A high CNF yield of nearly 10 g CNF g cat -1was achieved at 650°C after a reaction time of 3 h when the catalyst was subjected to a reduction at the same temperature for 2 h under a hydrogen flow prior to synthesis. As the reduction temperature increased from 450 to 650°C, both the yield and diameters of the CNFs increased. The beneficial effects of including hydrogen in the reaction mixture on the catalytic performance of Ni/ HAp and the purity of the grown CNFs were demonstrated.

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Synthesis, characterisation and performance evaluation of spinel-derived Ni/Al2O3 catalysts for various methane reforming reactions

Cited by 141 publications

References 46 publications

Development of Active and Stable Low Nickel Content Catalysts for Dry Reforming of Methane

Development of Active and Stable Low Nickel Content Catalysts for Dry Reforming of Methane

Ni Catalysts Supported on Modified Alumina for Diesel Steam Reforming

Growth of carbon nanofibers from methane on a hydroxyapatite-supported nickel catalyst

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