Characterization of reduced α-alumina-supported nickel catalysts by spectroscopic and chemisorption measurements

Poncelet, Georges; Centeno, M.A.; Molina, Rafael

doi:10.1016/j.apcata.2005.04.052

Cited by 126 publications

(62 citation statements)

References 40 publications

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“…T species are more difficult to reduce than Ni 2+ OC ones [23,27], while the latter coincides with experimental observations from studies dealing with the promotion effects of La on Ni-based catalysts [26]. The H2-TPR profile of P_LaNi/Al (Figure 3) revealed the presence of three reduction bands within two major reduction zones at temperatures across the range of 290-750 °C.…”

Section: +supporting

confidence: 64%

“…The small shoulder at 695 °C was assigned to the reduction of Ni 2+ species, either tetrahedrally coordinated (i.e., Ni ) in the crystalline structure of the support as per previous reports [22,27], or in La-Ni-Al containing species derived from the strong interaction between La and Ni ions [26]. The former interpretation stems from the widely accepted perception that Ni species are more difficult to reduce than Ni ones [23,27], while the latter coincides with experimental observations from studies dealing with the promotion effects of La on Ni-based catalysts [26]. Additional H2-TPR analyses of Ni/Al (12.5 wt %) and La/Al (6.4 wt %) were conducted to assist with interpretation of the P_LaNi/Al profile ( Figure 3).…”

Section: +mentioning

confidence: 98%

“…In contrast, nickel in P_LaNi/Al was presumed to have formed Ni-Al surface spinels since the occurrence of such species in Ni/Al systems is widely known [19][20][21][22][23][24]. According to Li et al the absence of XRD lines corresponding to these surface spinels results from their short-range three-dimensional order, provided that Ni ions only diffused into the first few outer layers of the Al 2 O 3 support during their 450 • C calcination stage [22].…”

Section: As-prepared Catalyst (P_lani/al)mentioning

confidence: 99%

“…Within Figure 4a the peaks at 856.49 and 862.72 eV for P_LaNi/Al correspond to the primary and shake-up lines of octahedrally coordinated Ni (Ni 2+ OC ) in nickel-alumina spinels, respectively [21,23,27,30]. According to Poncelet et al, enhanced reducibility in Ni/Al observed at high Ni loadings is associated with octahedral nickel (Ni 2+ OC ) species which resemble NiO [23]. These species would account for the low temperature reduction peak in the P_LaNi/Al TPR profile, provided that no bulk NiO signals (i.e., ca.…”

Section: +mentioning

confidence: 99%

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An Alumina-Supported Ni-La-Based Catalyst for Producing Synthetic Natural Gas

et al. 2016

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LaNi 5 , known for its hydrogen storage capability, was adapted to the form of a metal oxide-supported (γ-Al 2 O 3 ) catalyst and its performance for the Sabatier reaction assessed. The 20 wt % La-Ni/γ-Al 2 O 3 particles were prepared via solution combustion synthesis (SCS) and exhibited good catalytic activity, achieving a CO 2 conversion of 75% with a high CH 4 selectivity (98%) at 1 atm and 300 • C. Characteristics of the La-Ni/γ-Al 2 O 3 catalyst were identified at various stages of the catalytic process (as-prepared, activated, and post-reaction) and in-situ DRIFTS was used to probe the reaction mechanism. The as-prepared catalyst contained amorphous surface La-Ni spinels with particle sizes <6 nm. The reduction process altered the catalyst make-up where, despite the reducing conditions, Ni 2+ -based particles with diameters between 4 and 20 nm decorated with LaO x moieties were produced. However, the post-reaction catalyst had particle sizes of 4-9 nm and comprised metallic Ni, with the LaO x decoration reverting to a form akin to the as-prepared catalyst. DRIFTS analysis indicated that formates and adsorbed CO species were present on the catalyst surface during the reaction, implying the reaction proceeded via a H 2 -assisted and sequential CO 2 dissociation to C and O. These were then rapidly hydrogenated into CH 4 and H 2 O.

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Section: +supporting

confidence: 64%

Section: +mentioning

confidence: 98%

Section: As-prepared Catalyst (P_lani/al)mentioning

confidence: 99%

Section: +mentioning

confidence: 99%

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An Alumina-Supported Ni-La-Based Catalyst for Producing Synthetic Natural Gas

et al. 2016

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“…The peaks observed at 2θ = 36°, 45.8° and 65.3° corresponded to the formation of -Al2O3 lattice while NiO is only detected at the first peak at 2θ = 36°. This may be due to the reason that XRD can typically only detect metal crystallites that are larger than 2-5 nm and NiO crystallite sizes are smaller than the detection limit [17].…”

Section: Bulletin Of Chemical Reaction Engineering and Catalysis 11 (2mentioning

confidence: 99%

Thermo-Catalytic Methane Decomposition for Hydrogen Production: Effect of Palladium Promoter on Ni-based Catalysts

Mei

Lock

et al. 2016

Bull. Chem. React. Eng. Catal.

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Hydrogen production from the direct thermo-catalytic decomposition of methane is a promising alternative for clean fuel production. However, thermal decomposition of methane can hardly be of any practical and empirical interest in the industry unless highly efficient and effective catalysts, in terms of both catalytic activity and operational lifetime have been developed. In this study, the effect of palladium (Pd) as a promoter onto Ni supported on alumina catalyst has been investigated by using coprecipitation technique. The introduction of Pd promotes better catalytic activity, operational lifetime and thermal stability of the catalyst. As expected, highest methane conversion was achieved at reaction temperature of 800 °C while the bimetallic catalyst (1 wt.% Ni -1 wt.% Pd/Al2O3) gave the highest methane conversion of 70% over 15 min of time-on-stream (TOS). Interestingly, the introduction of Pd as promoter onto Ni-based catalyst also has a positive effect on the operational lifetime and thermal stability of the catalyst as the methane conversion has improved significantly over 240 min of TOS.

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Nickel Boosts Ring‐Opening Activity of Iridium

Ziaei-Azad

Semagina

2014

ChemCatChem

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A variety of bimetallic Ni–Ir catalysts were synthesised by preforming nanoparticles in the presence of polyvinylpyrrolidone, followed by deposition on γ‐alumina and high‐temperature polymer removal. The Ni–Ir (1:1 molar ratio) nanoparticles prepared by the hydrogen‐sacrificial technique (Ir reduction on the preformed Ni nanoparticles with surface Ni hydride) allowed increasing indane ring opening activity per total amount of Ir as compared to monometallic Ir. The simultaneous reduction of Ni and Ir precursors was not as efficient. The catalysts were characterised with UV/Vis spectroscopy, TEM, temperature‐programmed reduction, CO2 temperature‐programmed desorption, CO diffuse reflectance Fourier transform spectroscopy, X‐ray photoelectron spectroscopy and CHN analysis. The study only explored the catalyst’s metal function and allows saving rare and expensive iridium without loss of its outstanding performance as a ring‐opening catalyst.

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Characterization of reduced α-alumina-supported nickel catalysts by spectroscopic and chemisorption measurements

Cited by 126 publications

References 40 publications

An Alumina-Supported Ni-La-Based Catalyst for Producing Synthetic Natural Gas

An Alumina-Supported Ni-La-Based Catalyst for Producing Synthetic Natural Gas

Thermo-Catalytic Methane Decomposition for Hydrogen Production: Effect of Palladium Promoter on Ni-based Catalysts

Nickel Boosts Ring‐Opening Activity of Iridium

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