Palladium-enhanced reducibility of nickel in NaY

Feeley, Jennifer; Sachtler, Wolfgang M.H.

doi:10.1016/0144-2449(90)90055-v

Cited by 38 publications

(20 citation statements)

References 23 publications

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“…Compared to A 7 , the Ni 2+ reduction corresponding peak was shifted to lower temperature. Similar results were obtained by Feeley and Sachtler [33] studying Pd-Ni supported in HY zeolite, and this behavior was attributed to two effects: (1) an enhanced reduction of nickel species by interaction with reduced Pd particles present in the supercages, which can dissociatively chemisorb hydrogen, and (2) a Pd-Ni ion-pair formation or by nickel ions migration from hexagonal prisms to sodalite cages containing reduced Pd atoms. Our results suggest that segregate Ni and Pd particles were mainly formed on the zeolite surface [28], although it may also be possible physical Ni-Pd bimetallic interactions.…”

Section: September 2008supporting

confidence: 85%

“…Further, they observed the surface enrichment of aluminium and nickel. An enhanced reduction of Ni 2+ to Ni 0 by the addition of Pd was concluded by Feely and Sachtler [33] from their TPR study on Ni/NaYzeolite and Ni-Pd/NaY-zeolite. Thus, in the present case too, the added Pd is supposed to favor the reduction of nickel cations in the region 0-0.3 wt% Ni above which NiO is observed (for 0.5 wt%) in A series catalysts.…”

Section: -4 Xpsmentioning

confidence: 90%

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Effect of Ni in palladium β-zeolite on hydroisomerization of n-decane

Karthikeyan

Lingappan

Sivasankar

2008

Korean J. Chem. Eng.

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Bifunctional catalysts containing (0.1-0.5 wt%) Nickel and 0.1 wt% of Pd supported on H-β zeolite were synthesized by incipient wetness impregnation method and characterized by XRD, TEM, XPS, TPD and TPR techniques. The catalytic activity of Ni containing and Ni free Pd/H-β Catalysts was studied, and it was found that Ni up to a threshold value (0.3 wt% on β) produced increased the n-decane conversion and isomerization selectivity. When Ni content exceeds the threshold value, the conversion increases but isomerized products decrease. Moreover, Ni containing Pd/H-β showed increased sustainability and favored the protonated cyclopropane (PCP) intermediate mechanism in n-decane isomerization. The catalyst containing 0.3 wt% Ni 0.1 wt% Pd is adjudged as one performing better than other catalysts studied because of the isomerized mixture from it shows better octane number.

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Section: September 2008supporting

confidence: 85%

Section: -4 Xpsmentioning

confidence: 90%

Effect of Ni in palladium β-zeolite on hydroisomerization of n-decane

Karthikeyan

Lingappan

Sivasankar

2008

Korean J. Chem. Eng.

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“…As explained above (Jordão, 2007;Feeley and Sachtler, 1990) . Figure 3 also shows an EDX analysis in one region of the sample.…”

Section: +2mentioning

confidence: 86%

“…This occurs because the platinum cation is easily reduced and creates metallic sites that dissociate hydrogen molecules into atomic hydrogen, as stated by Jordão (2007) and Feeley and Sachtler (1990), this latter in the case of metallic Pd. Atomic hydrogen, in turn, reduces Ni +2 cations more rapidly than molecular hydrogen, thus decreasing the temperature (Jordão, 1999).…”

Section: +2mentioning

confidence: 99%

Bimetallic Pt-Ni catalysts supported on usy zeolite for n-hexane isomerization

Barsi

Cardoso

2009

Braz. J. Chem. Eng.

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-Isomerization of linear alkanes has had considerable importance for the refining industry because the isomers formed in this reaction have high octane number. Most works reported in the literature studied the use of bifunctional catalysts, i.e., ones that have acid sites and metallic sites. In this study, bifunctional monometallic (Ni or Pt) and bimetallic catalysts (Pt-Ni), using HUSY zeolite as the support, were prepared in order to verify the role of the metal content and composition on the catalytic properties for n-hexane isomerization. The method used for metal dispersion in the zeolite was competitive ion exchange using ammine complexes [Ni(NH 3 ) 6 ]Cl 2 and [Pt(NH 3 ) 4 ]Cl 2 as precursors. Four series of catalysts with constant atomic metal content had total metal amounts between 130 and 280 µmol M/g cat . Catalysts were characterized by temperature programmed reduction (TPR) and subjected to catalytic evaluation for n-hexane isomerization at 250 ºC and 1 atm using H 2 /C 6 = 9 molar ratio. TPR results show an easier reducibility of Ni +2 cations in the presence of Pt, which was evidenced by the displacement of the reduction peak of those cations towards lower temperatures in bimetallic catalysts. The bimetallic catalysts presented a higher activity in the isomerization of n-hexane when compared to the monometallic ones, as well better stability as the Pt content in the solid increases. The results of the activity as a function of the Pt content in the bimetallic catalysts show a maximum value around 50% of Pt. An addition of Pt above this critical value leads to a small decrease of the catalytic activity.

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“…Reaction [6] was observed on NiPd-containing zeolites at 773 K. 10 It is well known, however, that in the case of silver atoms in aqueous solutions 11 the analogous reaction takes place at room temperature. So we suppose that the majority of the Ni(I) is formed by reaction [6].…”

Section: Ni0 Sioh 3 Sioni Hámentioning

confidence: 96%

Characterization of nanosized nickel prepared by surface reactions of Ni-?-organyl complexes on silica: An electron paramagnetic and ferromagnetic resonance study

Drevs

Mörke

Jarsetz

et al. 1998

Appl. Organometal. Chem.

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Dispersed atomic nickel(0) is formed during the reaction of the nickel‐σ‐organyl complexes with silanol groups at temperatures below 373 K. That nickel is oxidized to Ni(I) by protons of the silanol groups in a consecutive step. The Ni(I) portion amounts to about 70% w/w of the Ni used. Six different Ni(I) species are detected by electron paramagnetic resonance. They are stabilized by interaction with the silica surface and the organic moieties; they act as anchor ions for the Ni(0) atoms. Ni(0) crystallites stabilized in this way are about 0.5 nm in diameter after a treatment at 373 K. The influence of the Ni(I) ions on the collective, magnetic properties of the clusters is revealed by calculation of ferromagnetic resonance (FMR) spectra using the independent‐grain approach according to Schlömann and Kotyukov. A strain of about 10 GPa is brought about in the nickel crystallites by the interaction with Ni(I) ions. © 1998 John Wiley & Sons, Ltd.

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Palladium-enhanced reducibility of nickel in NaY

Cited by 38 publications

References 23 publications

Effect of Ni in palladium β-zeolite on hydroisomerization of n-decane

Effect of Ni in palladium β-zeolite on hydroisomerization of n-decane

Bimetallic Pt-Ni catalysts supported on usy zeolite for n-hexane isomerization

Characterization of nanosized nickel prepared by surface reactions of Ni-?-organyl complexes on silica: An electron paramagnetic and ferromagnetic resonance study

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