The Nature of Residual OH Groups on a Series of Near-Faujasite Zeolites

Carter, J. L.; Lucchesi, P. J.; Yates, David J.

doi:10.1021/j100788a019

Cited by 63 publications

(14 citation statements)

References 3 publications

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“…Others have pointed out that the reactions being catalyzed must occur via protonic mechanisms lm4* s* l8 and have suggested that trace amounts of H20 18* 19* 2 2 or structural OH groups,8* 20- 22 which are introduced with the multivalent cations, may be responsible. These latter hydroxyl groups have been noted by various authors 16* 20- 24 and have been shown to have the same i.-r. stretching frequencies (3650 and 3545 cm-l) as those of the decationated zeolites,8* 21a-2 2 * 2 5 but no detailed study has been made of the changes which occur during the initial dehydration of zeolites containing various cations. Moreover, data are lacking which would allow one to distinguish among the views mentioned above.…”

supporting

confidence: 70%

“…*~ The frequencies of the acidic hydroxyl bands in the 3650 and 3545 cm-' regions decreased with increasing electron affinity 31 of the exchange cation. The present results are plotted along with data taken from the work of Angell and Schaffer 23 (for Y-zeolites) and Carter et aZ., 24 (for zeolites) in fig. 3, where a general decrease in frequency with increasing electron affinity of the exchange-cation is revealed.…”

Section: E H Y D R a T I O Nmentioning

confidence: 90%

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Studies of the hydrogen held by solids. Part 15.—Cation exchanged zeolites

Christner¹,

Liengme²,

Hall³

1968

Trans. Faraday Soc.

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Dehydration of multivalent ion-exchanged zeolites produced structural hydroxyl groups of varying thermal stability as evidenced by differences in the retention of their L-r. bands on heating in uacuo. The retention increased with the electron af6nity of the base-exchange cation. Although the i.-r. bands in the 3650 and 3545 cm-l regions appeared to have the same chemical identity as those formed by heating the NHZ-zeolite, these hydroxyl groups were less reactive with pyridine (Py). Temperatures of 85-150" were required to react a substantial fraction of them to PyH+, whereas with the decationated zeolites, both bands were removed by Py interaction at room temperature although the 3545 cm-' band could be restored to its original intensity by evacuation at 150".Py also co-ordinated with the base-exchange cations (became Lewis bonded). The strength of this interaction (retention of PyL at elevated temperatures) increased with the electron affinity of the cation and the frequency of the corresponding i.-r. band increased concomitantly from 1443 cm-' (Na+) to 1455 cm-l (Zn2+). Addition of H20, or H20+C02, effected conversion of PyL to PyH+, and again the extent of these reactions paralleled the electron affinity of the cation.

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supporting

confidence: 70%

Section: E H Y D R a T I O Nmentioning

confidence: 90%

Studies of the hydrogen held by solids. Part 15.—Cation exchanged zeolites

Christner¹,

Liengme²,

Hall³

1968

Trans. Faraday Soc.

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“…The initial endotherm at 110 "C due to dehydration is followed by a broad endotherm between 250-500 "C with centers at 300 and 420 "C. Margulis assigned the 300" peak to the loss of one molecule of water of zeolitic character according to CuO In an attempt to clarify the dispute we have followed the progress of decomposition of CuS04.3Cu(OH), between 110 and 530 "C by infrared spectroscopy and X-ray diffractometry. A solid bearing zeolitic water is expected to display the absorption band due to the bending mode of molecular water, ZOH, in the infrared region of 1700-1 600 cm-' as observed by Bertsch and Habgood (12) and Carter et al (13). Our infrared spectra of the compound heated up to 300 "C showed no absorption band characteristic of ZOH which confirms the results of Pannetier and coworkers and prompts us to rule out the presence and F, effects a merging of the band details attributed to the amorphous nature of the solid resulting in a broad band with shoulders barely in evidence.…”

Section: Differential Thermal Analysismentioning

confidence: 74%

Studies on metal hydroxy compounds. XII. Thermal analyses, decomposition kinetics, and infrared spectra of copper basic oxysalts

Ramamurthy¹,

Secco²

1970

Can. J. Chem.

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The thermal analyses of copper basic oxysalts of the type Cu?(OH),XO,, where X = S, C, C1, Br! I, N, H C and y = 4, 3, or 2 reveal that decomposition occurs, In most cases, by dehydroxylatlon w~t h concomitant disproportionation of the oxysalt. An outstanding exception to this pattern of decornposition is the basic sulfate. Calorimetric measurements along with related enthalpic values for the decornposition reaction are given.The kinetics of thermal decomposition of the compounds are classified into three main categories: (i) three-dimensional contracting sphere model, (ii) first-order rate, and (iii) nucleation controlled rate processes.The infrared spectral data of nine copper basic oxycompounds in the frequency region 4000-250 cm-' are presented with their assignments. The fundamental infrared inactive modes of the anionic species SO,'-, NO3-, etc. become active by the presence of the copper hydroxide ligand indicating a lowering of symmetry in the anion.

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“…The ESR parameters of species B are very similar to those for Cu(II)−alcohol complexes where Cu(II) coordinates to two molecules of methanol, ethanol, or propanol from the analysis of the ESEM data. Thus, Cu(II) species B is similarly suggested to coordinate to two molecules of H 2 O or OH formed by hydrolysis upon dehydration to form a Cu(O z ) 3 (H 2 O) 2 or Cu(O z ) 3 (OH) 2 complex also located in site SII*. This corresponds to the copper losing some water ligands during evacuation.…”

Section: Discussionmentioning

confidence: 96%

Cupric Ion Species in Cu(II)-Exchanged K−Offretite Gallosilicate Determined by Electron Spin Resonance and Electron Spin Echo Modulation Spectroscopies

Yu¹,

Ryoo²,

Hong³

et al. 1996

J. Phys. Chem.

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The location of Cu(II) and its interaction with deuterated adsorbates in Cu(II)-exchanged gallosilicate with the offretite channel-type structure were investigated by electron spin resonance (ESR) and electron spin echo modulation (ESEM) spectroscopies. It is suggested that in fresh, hydrated offretite gallosilicate Cu(II) is in the main channel coordinated to three water molecules and three framework oxygens in a six-ring window of an ε-cage to form distorted octahedral coordination. Upon evacuation at increasing temperature, Cu(II) moves from the main channel through an ε-cage to a hexagonal prism. Dehydration at 400 °C produces one Cu(II) species located in a recessed site in a hexagonal prism based on a lack of broadening of its ESR lines by oxygen. Adsorption of polar molecules such as water, alcohols, dimethyl sulfoxide, and ammonia causes changes in the ESR spectrum of the Cu(II), indicating migration into cation positions in the main channels where adsorbate coordination can occur. However, nonpolar ethylene does not cause migration of Cu(II). Cu(II) forms complexes with two molecules of methanol, ethanol, and propanol and one molecule of dimethyl sulfoxide based on ESEM data. Cu(II) is suggested to form a trigonal-bipyramidal complex with two ammonias in axial positions and three framework oxygens in a six-ring window of an ε-cage based on its ESR parameters and ESEM data.

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The Nature of Residual OH Groups on a Series of Near-Faujasite Zeolites

Cited by 63 publications

References 3 publications

Studies of the hydrogen held by solids. Part 15.—Cation exchanged zeolites

Studies of the hydrogen held by solids. Part 15.—Cation exchanged zeolites

Studies on metal hydroxy compounds. XII. Thermal analyses, decomposition kinetics, and infrared spectra of copper basic oxysalts

Cupric Ion Species in Cu(II)-Exchanged K−Offretite Gallosilicate Determined by Electron Spin Resonance and Electron Spin Echo Modulation Spectroscopies

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