Nature of the active sites and catalytic activity of SAPO-5 synthesized in the presence of nickel cations

Minchev, Christo; Zubkov, S. A.; Valtchev, Valentin; Minkov, V.; Micheva, N.; Kanazirev, V.

doi:10.1016/0926-860x(94)85191-3

Cited by 32 publications

(12 citation statements)

References 19 publications

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“…This type of acid sites was already observed in the case of other Ni-containing molecular sieves. Minchev et al [24] suggested that the nickel cations play the role of Lewis acid centers. Nkosi et al [6] reported that the acidity is due to the hydrolysis of the [Ni(H 2 O) 6 ] 2+ species (known as the Planck mechanism [25]).…”

Section: Characterization Of Catalystsmentioning

confidence: 99%

Ni-exchanged AlMCM-41?An efficient bifunctional catalyst for ethylene oligomerization

Hulea

Fajula

2004

Journal of Catalysis

137

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Section: Characterization Of Catalystsmentioning

confidence: 99%

Ni-exchanged AlMCM-41?An efficient bifunctional catalyst for ethylene oligomerization

Hulea

Fajula

2004

Journal of Catalysis

137

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“…4,5 On the other hand, both Bro ¨nsted and Lewis acidic sites of different strengths were observed on transition-metal-substituted AlPO 4 -5. 6 These metal-substituted materials were found to be catalytically active in xylene isomerization, [7][8][9] methanol conversion, 10,11 ethanol dehydration, 12 propanol dehydration, and propene oligomerization. 13 Moreover, redox catalytic activities were observed on AlPO 4 -5 substituted with manganese, 14 vanadium, [15][16][17][18][19][20][21] cobalt, 22,23 and chromium 24 in reactions such as ethane or propane oxydehydrogenation and cyclohexane oxidation to cyclohexanone and adipic acid.…”

Section: Introductionmentioning

confidence: 99%

Characterization of MnAPO-5 for Ethane Oxydehydrogenation

Chien

Wan

2000

Ind. Eng. Chem. Res.

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Manganese-substituted AlPO 4 -5 molecular sieve (MnAPO-5) was characterized by temperatureprogrammed reduction (TPR) and diffuse reflectance UV-Vis and electron paramagnetic resonance (EPR) spectroscopies, and the results were compared with those of manganese oxides impregnated on AlPO 4 -5 (Mn/AlPO 4 -5). It was found from TPR that the manganese interacted strongly with the aluminophosphate surface in MnAPO-5. Higher temperatures were required to reduce the manganese species on MnAPO-5 by hydrogen than to reduce those on Mn/AlPO 4 -5. The TPR, UV-Vis, and EPR results indicate that Mn 2+ or Mn 3+ was the major oxidation state of manganese in MnAPO-5, in which a small amount of MnO 2 or Mn 2 O 3 was also found. O 2was observed from AlPO 4 -5, MnAPO-5, and Mn/AlPO 4 -5 by EPR at g zz ) 2.021, g xx ) 2.008, and g yy ) 2.003; it existed on the surface of the aluminophosphate rather than being associated with manganese on either MnAPO-5 or Mn/AlPO 4 -5. A kinetic model involving oxygen and ethane adsorption was proposed for ethane oxydehydrogenation over MnAPO-5. The surface reaction was the rate-determining step. The activation energy for the reaction and the enthalpy and entropy changes for the adsorptions of ethane and oxygen were obtained in this study. Because positive entropy and enthalpy changes for oxygen chemisorption on the MnAPO-5 surface were found, it is proposed that surface rearrangement around the Mn catalytic center occurred during oxygen chemisorption.

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“…The quantities of weak B and L acid sites and strong B and L acid sites are obtained from the Py‐IR measurement results at both low (200 °C) and high (350 °C) desorption temperatures. As shown in Table , the amount of B and L acid sites reduce after Pd NPs introduction compared to the parent Beta zeolites, due to the coverage of Pd NPs over partial microporous channels, preventing pyridine molecules from diffusing into the pores to react with the acid sites. Meanwhile, the catalysts with cubic Pd NPs of different size (C‐9, C‐12, C‐16) exhibit similar amounts of B and total acid sites, compared to T‐18 catalysts.…”

Section: Resultsmentioning

confidence: 99%

The Influence of Size and Shape of Pd Nanoparticles on the Performances of Pd/Beta Catalysts for n‐Heptane Hydroisomerization

Chen

Liu²,

Yin

et al. 2019

ChemCatChem

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Several Pd/Beta catalysts with cubic (9 nm, 12 nm, 16 nm) and truncated-octahedral (18 nm) Pd nanoparticles (NPs) were prepared to investigate the effect of size and shape of Pd NPs for n-heptane hydroisomerization. Characterizations confirmed that the cubic Pd NPs solely exposed {100} crystal plane and truncated-octahedral Pd NPs were enclosed by {100} and {111} crystal planes, and that the desorption temperature of subsurface hydrogen on Pd NPs showed size and shape dependence.Hydroisomerization results exhibits that the catalyst with 9 nm cubic Pd NPs displayed the higher isomers selectivity compared to the catalyst with 12 nm cubic NPs, 18 nm truncated octahedral NPs and 16 nm cubic NPs at similar conversion. This result suggested the size and shape dependence of (de) hydrogenation activity of Pd NPs, and further revealed the key role of subsurface hydrogen in determining the (de)hydrogenation activity.interactions between slabs. The 3 × 3 × 1 Monkhorst-Pack k-point grid was used in the two surfaces for the Brillouin zone sampling.

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Nature of the active sites and catalytic activity of SAPO-5 synthesized in the presence of nickel cations

Cited by 32 publications

References 19 publications

Ni-exchanged AlMCM-41?An efficient bifunctional catalyst for ethylene oligomerization

Ni-exchanged AlMCM-41?An efficient bifunctional catalyst for ethylene oligomerization

Characterization of MnAPO-5 for Ethane Oxydehydrogenation

The Influence of Size and Shape of Pd Nanoparticles on the Performances of Pd/Beta Catalysts for n‐Heptane Hydroisomerization

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