Structural Characterization of Ni-Substituted Hexaaluminate Catalysts Using EXAFS, XANES, XPS, XRD, and TPR
The structure of five Ni-substituted Ba{sub 0.75}Ni{sub y}Al{sub 12-y}O{sub 19-{delta}} hexaaluminate catalysts at various Ni loadings (y = 0.2, 0.4, 0.6, 0.8 and 1.0) was investigated using EXAFS, XANES, XPS, XRD, and TPR. As Ni-substitution into the hexaaluminate lattice is increased, the unit cell dimension decreases along the c axis. This systematic change is consistent with Ni substitution for Al{sup 3+} in the hexaaluminate crystalline structure. XANES analysis suggests that Ni-O bonding is stronger for Ni substituted into the hexaaluminate lattice, relative to that of bulk NiO. The average coordination numbers obtained from EXAFS indicate that Ni is preferentially exchanging with tetrahedrally coordinated Al{sup 3+} in the structure which predominates in regions of the hexaaluminate unit cell near the mirror plane. It is at these sites that, preferential substitution of Ni{sup 2+} likely occurs to minimize strain in the crystalline lattice.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 1020131
- Report Number(s):
- BNL--95981-2011-JA
- Journal Information:
- Journal of Physical Chemistry C, Journal Name: Journal of Physical Chemistry C Journal Issue: 17 Vol. 114; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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