Electron spin resonance and electron spin-echo spectroscopic studies of supported-molybdenum catalysts. Interaction between molybdenum, adsorbate and oxygen molecules

1985 ◽  
Vol 81 (9) ◽  
pp. 2083 ◽  
Author(s):  
Ruiyun Y. Zhan ◽  
Mysore Narayana ◽  
Larry Kevan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Spectroscopic Studies ◽  
Spin Resonance ◽  
Molybdenum Catalysts

Electron spin resonance and electron spin echo spectroscopic studies of Cu2+ sites in synthetic cancrinite zeolites

1988 ◽  
Vol 66 (8) ◽  
pp. 1984-1988 ◽  
Author(s):  
P. Raghunathan ◽  
L. Kevan
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Spectroscopic Studies ◽  
Esr Spectra ◽  
Tetrahedral Symmetry ◽  
Activation Temperature ◽  
Spin Resonance ◽  
Hydrated Sample

Electron spin resonance (ESR) and electron spin echo modulation (ESEM) studies of Cu2+ sites introduced by ion exchange are reported in two types of synthetic cancrinite zeolites, one of them a more hydrated sample, Na6 Al6Si6O24•8H2O (denoted C1), and the other a less hydrated sample with entrained calcium carbonate, Na6Al6Si6O24•CaCO3•8H2O (denoted C2). ESR spectra reveal that C1 activated at 100 °C contains Cu2+ sites of tetrahedral symmetry with [Formula: see text] and [Formula: see text] while at a higher activation temperature of 400 °C Cu2+ sites with a different symmetry are produced corresponding to [Formula: see text] and [Formula: see text] C2 activated at 100 °C contains almost exclusively Cu2+ sites of trigonal symmetry with [Formula: see text] and [Formula: see text] Two- and three-pulse ESEM experiments at 4 K give 2D and 27Al modulation patterns that corroborate these ESR assignments. Possible locations of the Cu2+ sites in the C1 and C2 structures are proposed.

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