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J Mol Graph Model. 2013 Jun;43:31-40. doi: 10.1016/j.jmgm.2013.03.006. Epub 2013 Apr 8.

Effects of amine organic groups as lattice in ZSM-5 on the hydrolysis of dimethyl ether.

Author information

1
National Nanotechnology Center, National Science and Technology Development Agency, Klong Luang, Pathumthani 12120, Thailand.

Abstract

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.

PMID:
23681284
DOI:
10.1016/j.jmgm.2013.03.006
[Indexed for MEDLINE]

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