Fe ions in the cationic sites and in the skeleton of faujasites. A quantum chemical study

✍ Scribed by S. Beran; P. Jírů; B. Wichterlová

• Publisher: Elsevier Science
• Year: 1982
• Tongue: English
• Weight: 441 KB
• Volume: 2
• Category: Article
• ISSN: 0144-2449
• DOI: 10.1016/s0144-2449(82)80065-1

✦ Synopsis

The CNDO/2 method was used for calculation of the physico-chemical characteristics of faujasites with Fe 2+, Fe 3+ and Fe(OH) + ions localized in the SII and S I, cationic positions or with Fe 3+ ions incorporated in the zeolite skeleton, modelled using T606(OH)12 and FeTsO6(OH)12 clusters. It is demonstrated that the Fe cations are coordinated to the zeolite skeleton through a strong electron donor-acceptor bond, whose formation leads to marked donation of electron density to these cations, resulting in a relatively low charge on the Fe atoms of the cation-Fe 2+ ~ 0.4 and Fe 3+ ~ 1.2. Incorporation of the Fe 3+ ions into the zeolite skelton results in Fe-O bonds with strength comp~lrable to the analogous AI-O bonds, but weaker than the Si-O skeletal bonds. The Fe 3+ ion localized in the skeleton was found to be quite stable with respect to its possible reduction to Fe 2+.