Imaging individual lanthanum atoms in zeolite Y by scanning transmission electron microscopy: evidence of lanthanum pair sites
Images of La-exchanged NaY zeolite obtained with aberration-corrected scanning transmission electron microscopy (STEM) show that about 80% of the La cations were present as site-isolated species, with the remainder in pair sites. The distance between La cations in the pair sites ranged from 1.44 to 3.84 Å, consistent with the presence of pairs of cations tilted at various angles with respect to the support surface. The actual distance between La cations in the pair sites is inferred to be approximately 3.84 Å, which is shorter than the distance between the nearest Al sites in the zeolite (4.31 Å). The results therefore suggest the presence of dimeric structures of La cations bridged with OH groups, and the presence of such species has been inferred previously on the basis of X-ray photoelectron spectroscopy (W. Grünert, U. Sauerlandt, R. Schlögl, H.G. Karge, J. Phys. Chem., 97 (1993) 1413).
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1214897
- Report Number(s):
- PNNL-SA-104659; 47296
- Journal Information:
- Microporous and Mesoporous Materials, 213:95-99, Journal Name: Microporous and Mesoporous Materials, 213:95-99
- Country of Publication:
- United States
- Language:
- English
Similar Records
The effect of lanthanum promoter on the selectivity of Pd/zeolite-X in methanol synthesis
Effect of cations on methane adsorption by NaY, MgY, CaY, SrY, and BaY zeolites