In situ MAS NMR investigation of the hydrogenation of acrylonitrile on Pt- and Rh-containing zeolites Y

Henning, Harald; Dornbach, Mark; Scheibe, Matthias; Klemm, Elias; Hunger, Michael

doi:10.1016/j.micromeso.2012.06.021

Cited by 12 publications

(21 citation statements)

References 13 publications

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“…Besides signals of metal OH groups at 0.4−0.9 ppm and SiOH groups at 1.5−1.8 ppm, all spectra contain signals of bridging OH groups at 3.4−3.5 ppm, which did not occur in the spectrum of the parent zeolite Na−Y (not shown). 20,21 For a better quantification of the densities of Si(OH)Al groups in the noble metal-containing zeolites Y, the 29 Si as well as 27 Al MAS NMR spectra (c, d) of hydrated parent zeolite Na−Y (a, c) and zeolite 2.8Pd/H,Na−Y, recorded upon calcination, reduction, and rehydration (b, d).…”

Section: Resultsmentioning

confidence: 99%

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

et al. 2015

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In the present work, the generation and properties of Brønsted acidic bridging OH groups (Si(OH)Al) in Rh-, Ir-, Pd-, and Ptcontaining zeolites Y were quantitatively investigated by multinuclear solidstate NMR spectroscopy. The number of Si(OH)Al groups formed per noble metal atom upon their reduction was found to be 0.3 to 1.3 instead of the theoretically expected values of 2 (Pd 2+ , Pt 2+ ) or 3 (Rh 3+ , Ir 3+ ). For zeolites Y with low noble metal loadings, a significantly lower acid strength of Si(OH)Al groups in comparison with those of H,Na−Y zeolites occurred. Interestingly, noble metal-containing zeolites Y with lower acid strength have a significant content of not completely reduced noble metal atoms with partially cationic character. The spatial distribution of Si(OH)Al groups in noble metal-containing zeolites Y was found to differ significantly from that in H,Na−Y zeolites. This effect is explained by the migration of a significant content of noble metal atoms into the sodalite cages of zeolites Y already upon calcination of their noble metal complexes. Therefore, a much higher content of Si(OH)Al groups generated by the reduction of noble metal species in zeolites Y are located in sodalite cages compared to those in H,Na−Y zeolites.

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Section: Resultsmentioning

confidence: 99%

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

et al. 2015

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“…In past decades, various NMR techniques for the investigation of the mechanisms of heterogeneously catalyzed reactions were developed and demonstrated [10][11][12][13][14]. The application of NMR methods for studying the conversion of heavy hydrocarbons under flow conditions, however, is problematic due to the required high reaction temperatures and the intensity decreasing effect of Curie's law as well as the requirement of using expensive 13 C-enriched reactants [10].…”

Section: Introductionmentioning

confidence: 99%

Direct Proof of Volatile and Adsorbed Hydrocarbons on Solid Catalysts by Complementary NMR Methods

Lang

Dyballa

Traa

et al. 2021

Chemie Ingenieur Technik

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In this paper, both volatile and strongly adsorbed products of heavy hydrocarbon conversion on a zeolite were investigated by gas-phase and solid-state NMR. For this purpose, the reactions were carried out in sealed glass tubes under vacuum to collect the volatile reaction products. This procedure is demonstrated for pure 2-ethylphenol conversion on ultrastabilized zeolite Y leading to both the formation of light alkanes and deoxygenation products. The above-mentioned method is useful to improve the understanding of heavy hydrocarbon conversion under batch conditions.

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“…All solid-state NMR experiments were performed on a 500 MHz WB spectrometer (11.75 T) from Agilent Technologies in a custom-designed 4 mm MAS NMR probe allowing for continuous gas flow and sample heating. Resonance frequencies of 499.86, 125.69, and 130.25 MHz were employed for 1 H, 13 C, and 27 Al, respectively. 1 H and 13 C chemical shifts were referenced to adamantane.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Resonance frequencies of 499.86, 125.69, and 130.25 MHz were employed for 1 H, 13 C, and 27 Al, respectively. 1 H and 13 C chemical shifts were referenced to adamantane. 27 Al chemical shifts were referenced to a 1 M aqueous solution of Al(NO 3 ) 3 .…”

Section: ■ Introductionmentioning

confidence: 99%

Phase Transformations in Porous Materials Studied by In Situ Solid-State NMR Spectroscopy and In Situ X-ray Diffraction

et al. 2020

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Studying complex processes in solid phases such as adsorption or phase transitions in situ is the best way to obtain detailed and realistic insights on a molecular level. Besides in situ X-ray diffraction techniques, magic angle spinning (MAS) solidstate NMR spectroscopy is one of the most powerful analytical techniques. The implementation of in situ and operando MAS NMR is however challenging and requires dedicated hardware. We introduce here a new 4.0 mm wide-bore probe that allows for a continuous and well-distributed flow of gaseous adsorbates or reactants through the packed sample, as well as uniform heating of the sample and spinning of the rotor at the magic angle. The combination of both in situ MAS NMR and in situ powder X-ray diffraction allowed us to obtain new insights into two phase transformation mechanisms in crystalline, porous materials, viz. that of aluminophosphate VPI-5 into AlPO 4 -8 and that of metal− organic frameworks from the MIL-53 family during water adsorption and desorption.

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In situ MAS NMR investigation of the hydrogenation of acrylonitrile on Pt- and Rh-containing zeolites Y

Cited by 12 publications

References 13 publications

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

Generation and Properties of Brønsted Acid Sites in Bifunctional Rh-, Ir-, Pd-, and Pt-Containing Zeolites Y Investigated by Solid-State NMR Spectroscopy

Direct Proof of Volatile and Adsorbed Hydrocarbons on Solid Catalysts by Complementary NMR Methods

Phase Transformations in Porous Materials Studied by In Situ Solid-State NMR Spectroscopy and In Situ X-ray Diffraction

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