Electron spin resonance and electron spin echo modulation studies of oxomolybdenum species in thermally reduced MoH-SAPO-5 and MoH-SAPO-11 silicoaluminophosphate molecular sieves: Comparison of adsorbate coordination with CuH-SAPO-5 and CuH-SAPO-11
- Univ. of Houston, TX (United States)
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 coordinated 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.
- OSTI ID:
- 5463192
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 97:45; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MOLYBDENUM COMPLEXES
ELECTRON SPIN RESONANCE
SYNTHESIS
ADSORPTION
AMMONIA
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COPPER COMPLEXES
DEHYDRATION
DEUTERIUM COMPOUNDS
EXPERIMENTAL DATA
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MOLECULAR SIEVES
OXYGEN
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NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
RESONANCE
SORPTION
TRANSITION ELEMENT COMPLEXES
WATER
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