Effects of amine organic groups as lattice in ZSM-5 on the hydrolysis of dimethyl ether.
J Mol Graph Model
; 43: 31-40, 2013 Jun.
Article
em En
| MEDLINE
| ID: mdl-23681284
The effects of doping amine to ZSM-5 on its catalytic activity for hydrolysis of dimethyl ether (DME) have been studied theoretically using Density Functional Theory with the embedded cluster ONIOM(M06/6-31G(d,p):UFF) model. Doping by amine to ZSM-5 yields two new active centers, namely the protonated Z[NH2] and non-protonated Z[NH] amine sites in addition to the normal Brønsted acid Z[OH] site. The reaction has two possible stepwise and concerted channels. The stepwise channel consists of two elementary steps; (i) the demethylation followed by (ii) the hydrolysis while the concerted channel involves in the demethylation and hydrolysis in a single step. We found that the reaction favors to proceed via the concerted channel at all three active centers. The results predict that the Z[OH] shows the best catalytic performance for the studied reaction. The Z[NH2] is not catalytically active due to the activation barriers are extremely high for both stepwise and concerted pathways. The demethylation step is energetically favorable over the Z[NH] site, however, the product methylamonium surface intermediate is too stable to be further converted to methanol.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Zeolitas
/
Éteres Metílicos
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article