PMID- 16852665
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20070626
LR  - 20060720
IS  - 1520-6106 (Print)
IS  - 1520-5207 (Linking)
VI  - 109
IP  - 27
DP  - 2005 Jul 14
TI  - Theoretical study of modes of adsorption of water dimer on H-ZSM-5 and 
      H-Faujasite zeolites.
PG  - 13342-51
AB  - Modes of adsorption of water dimer on H-ZSM-5 and H-Faujasite (H-FAU) zeolites 
      have been investigated by a quantum embedded cluster approach, using the hybrid 
      B3LYP density functional theory. The results indicate that there are two possible 
      adsorption pathways, namely the stepwise process where only one water binds 
      strongly to the (-O)3-Al-O(H) tetrahedral unit while the other weakly binds to 
      the zeolite framework and the concerted process where both water molecules form a 
      large ring of hydrogen-bonding network with the Bronsted proton and an oxygen 
      framework. With inclusion of the effects of the Madelung potential from the 
      extended zeolite framework, for adsorption on H-ZSM-5 zeolite, both the neutral 
      and ion-pair complexes exist with adsorption energies of -15.13 and -14.73 
      kcal/mol, respectively. For adsorption on the H-FAU, only the ion-pair complex 
      exists with the adsorption energy of -14.63 kcal/mol. Our results indicate that 
      adsorption properties depend not only on the acidity of the Bronsted acidic site 
      but also on the topology of the zeolite framework, such as on the spatial 
      confinement effects which lead to very different adsorption structures for the 
      ion-pair complexes in H-ZSM-5 and H-FAU, even though their adsorption energies 
      are quite similar. Our calculated vibrational spectra for these ion-pair 
      complexes support previous experimental IR interpretations.
FAU - Jungsuttiwong, Siriporn
AU  - Jungsuttiwong S
AD  - Henry Eyring Center for Theoretical Chemistry, Chemistry Department, University 
      of Utah, 315 S 1400 E, Room 2020, Salt Lake City, Utah 84112, USA.
FAU - Limtrakul, Jumras
AU  - Limtrakul J
FAU - Truong, Thanh N
AU  - Truong TN
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Phys Chem B
JT  - The journal of physical chemistry. B
JID - 101157530
EDAT- 2006/07/21 09:00
MHDA- 2006/07/21 09:01
CRDT- 2006/07/21 09:00
PHST- 2006/07/21 09:00 [pubmed]
PHST- 2006/07/21 09:01 [medline]
PHST- 2006/07/21 09:00 [entrez]
AID - 10.1021/jp045021k [doi]
PST - ppublish
SO  - J Phys Chem B. 2005 Jul 14;109(27):13342-51. doi: 10.1021/jp045021k.