Studies of Fe(III) incorporated into AlPO4-20 by X- and W-band EPR spectroscopies

Arieli, D.; Vaughan, D. E. W.; Strohmaier, Karl G.; Thomann, H.; Bernardo, M.; Goldfarb, Daniella

doi:10.1002/(sici)1097-458x(199912)37:13<s43::aid-mrc569>3.0.co;2-7

Cited by 29 publications

(19 citation statements)

References 56 publications

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“…Such iron would only be detected by elemental analysis and not by 31 P NMR spectroscopy. The possibility of leaching and the presence of extraframework iron were mentioned already in ref 23. The overall accuracy of the measurement could be improved if more reliable relaxation analysis a Obtained using eq 1. b Using g ) 2, B0 ) 7 T, and r ) 0.34 nm.…”

Section: Resultsmentioning

confidence: 94%

³¹P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes

2005

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The incorporation of moderate amounts of Ni(II), Co(II), Fe(II/III), and Mn(II/III) into aluminophosphate zeotype AlPO4-34 and Fe(II/III) into aluminophosphate zeotype AlPO4-36 was studied by broadline 31P NMR. The technique provided direct evidence on isomorphous substitution of framework aluminum by transition metals and allowed us to determine the extent of the substitution. 31P NMR proved to be complementary to other spectroscopic techniques such as X-ray absorption spectroscopy (XAS), Mössbauer, electron paramagnetic resonance (EPR), and electron nuclear double resonance (ENDOR) spectroscopies. The position of the NMR signal belonging to phosphorus in the P(OAl)3(OMe) environment depended mostly on the magnitude of the hyperfine interaction between a phosphorus nucleus and an unpaired electron, which was delocalized from the transition metal atom Me by covalent bonding. The width of the NMR signal was dominated by dipolar coupling among phosphorus nuclei and nearest paramagnetic centers. In addition, broadline NMR of ethylenediamine-templated manganese phosphate (C2H10N2)[Mn2(HPO4)3(H2O)], which was used as a model compound, showed that on the basis of line positions and line widths different 31P signals could easily be assigned to different phosphorus crystallographic sites. The technique could thus be applied to extract valuable structural information about metal phosphates as well.

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Section: Resultsmentioning

confidence: 94%

³¹P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes

2005

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“…This strain also prevents an unambiguous determination of Z (E/D), which was set to 0.33 in all cases. This was done based on an earlier study of Fe-AlPO 4 -20 34 and it corresponds to the maximum E value where ZFS broadening effects the largest. The line width used in the simulations of the Q-band EPR spectra is larger than that used for the W-and G-band spectra.…”

Section: Cw Epr and 1 H Endor Experimentsmentioning

confidence: 99%

Resolving Mn framework sites in large cage aluminophosphate zeotypes by high field EPR and ENDOR spectroscopy

Arieli

Prisner

Hertel

et al. 2004

Phys. Chem. Chem. Phys.

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“…One of the most fascinating researches on microporous AlPO 4 -n materials is the process of isomorphous substitution, in which framework Al 3+ and/or P 5+ ions are replaced by e.g. transition metal ions, such as Mn 2+ [3][4][5][6], Fe 3+ [7,8], V 4+ [9][10][11][12][13], Ti 4+ [14,15], Zn 2+ [16,17], Nb 5+ [18], Cr 3+ [19][20][21] and Co 2+ [22][23][24][25][26]. This process can generate Brö nsted acid and redox sites, leading to intriguing shape-selective catalytic performances.…”

Section: Introductionmentioning

confidence: 99%

“…This process can generate Brö nsted acid and redox sites, leading to intriguing shape-selective catalytic performances. The incorporation of Co 2+ (d 7 ) can be considered as a showcase for these substituted materials since this transition metal ion not only gives the solid an intense blue color and interesting oxidation properties, but also provides convincing spectroscopic evidence for the framework substitution of Co 2+ as obtained with e.g. diffuse reflectance UV-Vis-NIR spectroscopy, electron spin resonance and X-ray absorption spectroscopy [1, 3,[22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Solvent effects in the synthesis of CoAPO-5, -11 and -34 molecular sieves

Fan

Dou

et al. 2005

Microporous and Mesoporous Materials

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Series of CoAPO-5, CoAPO-11 and CoAPO-34 molecular sieves have been synthesized starting from a synthesis gel varying in its amount of Co 2+ and type of solvent molecule. Four protonic solvents have been investigated: water, ethanol, ethylene glycol and glycerol. The obtained crystalline materials were characterized with X-ray diffraction; diffuse reflectance UV-Vis-NIR spectroscopy; infrared spectroscopy; elemental analysis; electron microscopy microprobe analysis and thermo-gravimetrical analysis. It was found that the type of solvent has a strong influence on the crystallization behavior and the substitution degree of Co 2+ for Al 3+ in the framework of microporous aluminophosphates. Ethanol, ethylene glycol and glycerol seem to be the best solvents for the synthesis of single-phase and highly crystalline Co-rich CoAPO-34, CoAPO-11 and CoAPO-5 molecular sieves, respectively. By varying the type of solvent molecule, Co content and template amount in the synthesis gel it was possible to increase the substitution degree of framework Co 2+ in microporous aluminophosphates. In this manner, around 10%, 25% and 36% of Al 3+ could be replaced by Co 2+ in the framework of CoAPO-11, CoAPO-5 and CoAPO-34, respectively. These substitution degrees are substantially higher than those for CoAPO materials synthesized in the presence of water.

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Studies of Fe(III) incorporated into AlPO4-20 by X- and W-band EPR spectroscopies

Cited by 29 publications

References 56 publications

³¹P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes

³¹P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes

Resolving Mn framework sites in large cage aluminophosphate zeotypes by high field EPR and ENDOR spectroscopy

Solvent effects in the synthesis of CoAPO-5, -11 and -34 molecular sieves

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Studies of Fe(III) incorporated into AlPO4-20 by X- and W-band EPR spectroscopies

Cited by 29 publications

References 56 publications

31P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes

31P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes

Resolving Mn framework sites in large cage aluminophosphate zeotypes by high field EPR and ENDOR spectroscopy

Solvent effects in the synthesis of CoAPO-5, -11 and -34 molecular sieves

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³¹P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes

³¹P NMR as a Tool for Studying Incorporation of Ni, Co, Fe, and Mn into Aluminophosphate Zeotypes