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Title: Electron spin resonance and electron spin echo modulation studies of ion-exchanged NiH-SAPO-17 and NiH-SAPO-35 molecular sieves: Comparison with ion-exchanged NiH-SAPO-34 molecular sieve

Abstract

Erionite-like silicoaluminophosphate molecular sieve SAPO-17 and levyne-like SAPO-35, in which Ni ions were incorporated via solid-state ion-exchange into known extra framework sites, have been studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM). The Ni ion reducibility, location, and interaction with several adsorbates have been investigated. Among these adsorbates, the interaction with nitric oxide was emphasized and compared to that of Ni ion with NO in the previously studied chabazite-like SAPO-34. Room-temperature adsorption of C{sub 2}D{sub 4} on NiH-SAPO-17 after dehydration at 573 K, oxygen treatment at 823 K, evacuation, and subsequent hydrogen treatment at 573 K produces two Ni-ethylene complexes. Carbon monoxide adsorption gives rise to a Ni(I)-(CO){sub n} complex with unresolved {sup 13}C hyperfine lines. Following the kinetics of nitric oxide adsorption on NiH-SAPO-17 shows that initially, a Ni(I)-(NO){sup +} complex, a NO radical, and a new species which appears to be another NO species are generated. After a reaction time of 24 h, NO{sub 2} is observed. As the adsorption time further increases, NO{sub 2} becomes stronger while Ni(I)-(NO){sup +} decays, and after 5 days only NO{sub 2} remains. NO adsorption on NiH-SAPO-35 shows different features. Initially, two Ni(I)-(NO){sup +} complexes along with amore » NO radical are seen. As the adsorption time increases, one of the Ni(I)-(NO){sup +} complexes decreases in intensity while the other one increases, and after a few days only one Ni(I)-(NO){sup +} complex remains. Simulation of the {sup 31}P ESEM spectrum, supplemented by {sup 27}Al modulation, suggests that, upon dehydration, Ni ions in NiH-SAPO-17 migrate from the erioinite supercage to the smaller cancrinite cage. In dehydrated NiH-SAPO-17 migrate from the erionite supercage to the smaller cancrinite cage. In dehydrated NiH-SAPO-34 and NiH-SAPO-35, Ni ions remain in the large chabazite and levyne cages, respectively. As a consequence, Ni(II) in NiH-SAPO-17 is less sensitive to reduction by hydrogen than it is in NiH-SAPO-34 and NiH-SAPO-35.« less

Authors:
; ; ;  [1]
  1. Univ. of Houston, TX (United States). Dept. of Chemistry
Publication Date:
Sponsoring Org.:
National Science Foundation, Washington, DC (United States); Welch (Robert A.) Foundation, Houston, TX (United States); USDOE, Washington, DC (United States)
OSTI Identifier:
696651
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical; Journal Volume: 103; Journal Issue: 34; Other Information: PBD: 26 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; MOLECULAR SIEVES; CATALYSTS; TRANSITION ELEMENTS; ELECTRON SPIN RESONANCE; ACOUSTIC ESR; NICKEL; REDUCTION; ION EXCHANGE

Citation Formats

Djieugoue, M.A., Prakash, A.M., Zhu, Z., and Kevan, L.. Electron spin resonance and electron spin echo modulation studies of ion-exchanged NiH-SAPO-17 and NiH-SAPO-35 molecular sieves: Comparison with ion-exchanged NiH-SAPO-34 molecular sieve. United States: N. p., 1999. Web. doi:10.1021/jp9916844.
Djieugoue, M.A., Prakash, A.M., Zhu, Z., & Kevan, L.. Electron spin resonance and electron spin echo modulation studies of ion-exchanged NiH-SAPO-17 and NiH-SAPO-35 molecular sieves: Comparison with ion-exchanged NiH-SAPO-34 molecular sieve. United States. doi:10.1021/jp9916844.
Djieugoue, M.A., Prakash, A.M., Zhu, Z., and Kevan, L.. Thu . "Electron spin resonance and electron spin echo modulation studies of ion-exchanged NiH-SAPO-17 and NiH-SAPO-35 molecular sieves: Comparison with ion-exchanged NiH-SAPO-34 molecular sieve". United States. doi:10.1021/jp9916844.
@article{osti_696651,
title = {Electron spin resonance and electron spin echo modulation studies of ion-exchanged NiH-SAPO-17 and NiH-SAPO-35 molecular sieves: Comparison with ion-exchanged NiH-SAPO-34 molecular sieve},
author = {Djieugoue, M.A. and Prakash, A.M. and Zhu, Z. and Kevan, L.},
abstractNote = {Erionite-like silicoaluminophosphate molecular sieve SAPO-17 and levyne-like SAPO-35, in which Ni ions were incorporated via solid-state ion-exchange into known extra framework sites, have been studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM). The Ni ion reducibility, location, and interaction with several adsorbates have been investigated. Among these adsorbates, the interaction with nitric oxide was emphasized and compared to that of Ni ion with NO in the previously studied chabazite-like SAPO-34. Room-temperature adsorption of C{sub 2}D{sub 4} on NiH-SAPO-17 after dehydration at 573 K, oxygen treatment at 823 K, evacuation, and subsequent hydrogen treatment at 573 K produces two Ni-ethylene complexes. Carbon monoxide adsorption gives rise to a Ni(I)-(CO){sub n} complex with unresolved {sup 13}C hyperfine lines. Following the kinetics of nitric oxide adsorption on NiH-SAPO-17 shows that initially, a Ni(I)-(NO){sup +} complex, a NO radical, and a new species which appears to be another NO species are generated. After a reaction time of 24 h, NO{sub 2} is observed. As the adsorption time further increases, NO{sub 2} becomes stronger while Ni(I)-(NO){sup +} decays, and after 5 days only NO{sub 2} remains. NO adsorption on NiH-SAPO-35 shows different features. Initially, two Ni(I)-(NO){sup +} complexes along with a NO radical are seen. As the adsorption time increases, one of the Ni(I)-(NO){sup +} complexes decreases in intensity while the other one increases, and after a few days only one Ni(I)-(NO){sup +} complex remains. Simulation of the {sup 31}P ESEM spectrum, supplemented by {sup 27}Al modulation, suggests that, upon dehydration, Ni ions in NiH-SAPO-17 migrate from the erioinite supercage to the smaller cancrinite cage. In dehydrated NiH-SAPO-17 migrate from the erionite supercage to the smaller cancrinite cage. In dehydrated NiH-SAPO-34 and NiH-SAPO-35, Ni ions remain in the large chabazite and levyne cages, respectively. As a consequence, Ni(II) in NiH-SAPO-17 is less sensitive to reduction by hydrogen than it is in NiH-SAPO-34 and NiH-SAPO-35.},
doi = {10.1021/jp9916844},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
number = 34,
volume = 103,
place = {United States},
year = {Thu Aug 26 00:00:00 EDT 1999},
month = {Thu Aug 26 00:00:00 EDT 1999}
}
  • Erionite-like silicoaluminophosphate molecular sieve SAPO-17 and levyne-like SAPO-35, in which Ni ions were incorporated via solid-state ion-exchange into known extra framework sites, have been studied by electron spin resonance (ESR) and electron spin echo modulation (ESEM). The Ni ion reducibility, location, and interaction with several adsorbates have been investigated. Among these adsorbates, the interaction with nitric oxide was emphasized and compared to that of Ni ion with NO in the previously studied chabazite-like SAPO-34. Room-temperature adsorption of C[sub 2]D[sub 4] on NiH-SAPO-17 after dehydration at 573 K, oxygen treatment at 823 K, evacuation, and subsequent hydrogen treatment at 573 Kmore » produces two Ni-ethylene complexes. Carbon monoxide adsorption gives rise to a Ni(I)-(CO)[sub n] complex with unresolved [sup 13]C hyperfine lines. Following the kinetics of nitric oxide adsorption on NiH-SAPO-17 shows that initially, a Ni(I)-(NO)[sup +] complex, a NO radical, and a new species which appears to be another NO species are generated. After a reaction time of 24 h, NO[sub 2] is observed. As the adsorption time further increases, NO[sub 2] becomes stronger while Ni(I)-(NO)[sup +] decays, and after 5 days only NO[sub 2] remains. NO adsorption on NiH-SAPO-35 shows different features. Initially, two Ni(I)-(NO)[sup +] complexes along with a NO radical are seen. As the adsorption time increases, one of the Ni(I)-(NO)[sup +] complexes decreases in intensity while the other one increases, and after a few days only one Ni(I)-(NO)[sup +] complex remains. Simulation of the [sup 31]P ESEM spectrum, supplemented by [sup 27]Al modulation, suggests that, upon dehydration, Ni ions in NiH-SAPO-17 migrate from the erioinite supercage to the smaller cancrinite cage. In dehydrated NiH-SAPO-17 migrate from the erionite supercage to the smaller cancrinite cage. In dehydrated NiH-SAPO-34 and NiH-SAPO-35, Ni ions remain in the large chabazite and levyne cages, respectively. As a consequence, Ni(II) in NiH-SAPO-17 is less sensitive to reduction by hydrogen than it is in NiH-SAPO-34 and NiH-SAPO-35.« less
  • Molybdenum-doped H-SAPO-5 and H-SAPO-11 were prepared by a solid-state reaction with MoO[sub 3] to produce MoH-SAPO-5 and MoH-SAPO-11. After dehydration, paramagnetic Mo(V) species are generated and detected by electron spin resonance (ESR) with g[sub e] > g[sub [perpendicular]] > g[sub [parallel]]. A rhombic ESR signal is observed after adsorption of D[sub 2]O, CD[sub 3]OH, and CH[sub 3]OD. Upon O[sub 2] adsorption, the Mo(V) ESR signal intensity decreases and an O[sub 2][sup [minus]] radical is formed. The location and coordination geometry of Mo(V) have been determined by three-pulse electron spin echo modulation data and simulations. For MoH-SAPO-5, Mo(V) is directly coordinatedmore » to three D[sub 2]O and two CD[sub 3]OH, but for MoH-SAPO-11, Mo(V) is directly coordinated only to two D[sub 2]O and one CD[sub 3]OH. The coordination distances are longer and the number of coordinated adsorbates is less than for Cu(II)-doped H-SAPO-5 and H-SAPO-11. These differences are consistent with Mo(V) being an oxomolybdenum species, likely (MoO[sub 2])[sup +], in these SAPO materials. 31 refs., 6 figs., 3 tabs.« less
  • This study focuses on paramagnetic silver species produced by [gamma]-radiolysis of a silver silicoaluminophosphate-42 (Ag-SAPO-42) molecular sieve. Electron spin resonance and electron spin echo modulation spectroscopies have been used to study the structure, location, and coordination of silver adducts and clusters stabilized in dehydrated SAPO-42 and exposed to methanol and ammonia. It was found that in dehydrated AG-SAPO-42, small silver clusters are formed with very low yield, whereas, in AgNa-A, Ag[sub 3][sup 2+] or AG[sub 6][sup b+] clusters are efficiently stabilized. The less restricted mobility of Ag[sup 0] in SAPO-42 due to its lower cation capacity is postulated to explainmore » the observed differences. In the presence of methanol and ammonia in the molecular sieve cages, the differences are less significant. The major paramagnetic products of radiolysis in both SAPO-42 and type A molecular sieves are silver methoxy radicals (methanol adsorbed) or silver-ammonia adducts (ammonia adsorbed). They are located in [alpha]-cages, although the electron spin echo modulation results suggest some differences in location, possibly due to a different distribution of negative charge between the aluminophosphate and aluminosilicate frameworks. 22 refs., 7 figs., 1 tab.« less
  • This paper explores the possibility of using Pd ions in SAPO-11 by adding [Pd(NH{sub 3}){sub 4}]{sub 2+} during the synthesis of SAPO-11 to form PdSAPO-11, which is compared with solid-state ion exchange PdSAPO-11 and impregnation PdH-SAPO-11 in which palladium is in an extraframework position. Electron spin resonance and electron spin echo modulation spectroscopies are used to determine if the palladium position in PdSAPO-11 is located in a framework or extraframework.
  • ESR and ESEM are used in this paper to study Cu(II) ion location and interaction with water, alcohols, ammonia, and ethylene in the solid-state reactions of H-SAPO-34 with various copper compounds (CuO, CuCl{sub 2}, CuF{sub 2}). The Cu(II) ions migrate from the exterior to the interior of the molecular sieve similar to an aqueous ion exchange method. Two types of Cu(II) complexes form during the adsorption of methanol, but only one complex type forms with the rest of the adsorbates. Cu(II) interactions with other adsorbate molecules are also discussed. 20 refs., 3 figs., 2 tabs.