Journal article
Monocopper Active Site for Partial Methane Oxidation in Cu-Exchanged 8MR Zeolites
SUNCAT Center for Interface Science and Catalysis, Department of Chemical Engineering1
SUNCAT Center for Interface Science and Catalysis2
Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology3
Institute of Catalysis Research and Technology4
Institute for Chemical Technology and Polymer Chemistry5
Direct conversion of methane to methanol using oxygen is experiencing renewed interest owing to the availability of new natural gas resources. Copper-exchanged zeolites such as mordenite and ZSM-5 have shown encouraging results, and di- and tri-copper species have been suggested as active sites. Recently, small eight-membered ring (8MR) zeolites including SSZ-13, -16, and -39 have been shown to be active for methane oxidation, but the active sites and reaction mechanisms in these 8MR zeolites are not known.
In this work, we use density functional theory (DFT) calculations to systematically evaluate monocopper species as active sites for the partial methane oxidation reaction in Cu-exchanged SSZ-13. On the basis of kinetic and thermodynamic arguments, we suggest that [CuIIOH]+ species in the 8MR are responsible for the experimentally observed activity.
Our results successfully explain the available spectroscopic data and experimental observations including (i) the necessity of water for methanol extraction and (ii) the effect of Si/Al ratio on the catalyst activity. Monocopper species have not yet been suggested as an active site for the partial methane oxidation reaction, and our results suggest that [CuIIOH]+ active site may provide complementary routes for methane activation in zeolites in addition to the known [Cu–O–Cu]2+ and Cu3O3 motifs.
Language: | English |
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Publisher: | American Chemical Society |
Year: | 2016 |
Pages: | 6531-6536 |
ISSN: | 21555435 |
Types: | Journal article |
DOI: | 10.1021/acscatal.6b01895 |