Effect of the Al Siting on the Structure of Co(II) and Cu(II) Cationic Sites in Ferrierite. A Periodic DFT Molecular Dynamics and FTIR Study

Autor(en)

Stepan Sklenak, Prokopis C. Andrikopoulos, Sarah R. Whittleton, Hana Jirglova, Petr Sazama, Lubomir Benco, Tomas Bucko, Juergen Hafner, Zdenek Sobalik

Abstrakt

Periodic DFT molecular dynamics and FTIR spectroscopy were used to

investigate the cationic sites of ferrierite exchanged with Co(II) and

Cu(II) and their complexes with NO. Particular attention was paid to the

effect of the Al siting in six-membered rings forming the cationic

sites on the structure of these sites and the corresponding binding

energies of Me(II) (Me = Co and Cu). Our calculations show that both the

cations upon binding to cationic sites induce a rearrangement of the

local structure of the zeolite framework. The rearrangement is

significant for the α and β-2 sites while it is minor for the β-1 site.

Comparison of the observed and theoretical NO stretching frequencies of

ferrierite Co(II) and Cu(II) complexes with a NO molecule permitted the

assignment of IR bands to the individual types of cationic sites. For

NO-Co-ferrierite, the IR bands found at 1956, 1941, and 1935 cm^–1

can be assigned to NO-Co complexes with Co(II) located in the α, β-1,

and β-2 sites, respectively. Similarly for NO-Cu-ferrierite, the

frequencies of 1864, 1912, 1904, and 1892 cm^–1 belong to

NO-Cu complexes having Cu(II) accommodated in the α, β-1, β-2 (conformer

1), and β-2 (conformer 2) sites, respectively. The calculated

adsorption energies are systematically higher for Co(II) than for Cu(II)

for all the three sites and are in the order α > β-2 > β-1 for

both the cations. Our computational results further reveal that upon

binding Me(II) both the local structure of the zeolite framework as well

as the binding energies of Me(II) strongly depend on the Al siting in

the rings forming the cationic sites. The calculated relative binding

energies of Me(II) are in the order β-1 > β-2 > α for both the

cations. The general tendency of Me(II) accommodated in a cationic site

to react is inversely proportional to the corresponding binding

energies. We also showed that FTIR spectroscopy of complexes of NO and

Me(II)-exchanged ferrierite can serve to identify the Al siting in the

six-membered rings forming cationic sites.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

Czech Academy of Sciences

Journal

The Journal of Physical Chemistry Part C (Nanomaterials and Interfaces)

Band

117

Seiten

3958-3968

Anzahl der Seiten

11

ISSN

1932-7447

DOI

https://doi.org/10.1021/jp310236d

Publikationsdatum

02-2013

Peer-reviewed

Ja

ÖFOS 2012

103009 Festkörperphysik, 103015 Kondensierte Materie, 103025 Quantenmechanik, 103036 Theoretische Physik

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/77224eee-d553-43a8-a4e9-afd6559f2779