Jump to main content
Jump to site search

Issue 22, 2018
Previous Article Next Article

DFT exploration of active site motifs in methane hydroxylation by Ni-ZSM-5 zeolite

Author affiliations

Abstract

The O2-activated Ni-ZSM-5 zeolite is a promising catalyst for the selective oxidation (hydroxylation) of methane to methanol. While UV-vis spectra analyses (Shan et al. Langmuir 2014, 30, 8558–8569) have proposed bent mono(μ-oxo)dinickel [Ni2(μ-O)]2+ as the active site in Ni-ZSM-5, calculations based on density functional theory (DFT) have shown that methane activation on such an active site motif leads to a very high activation barrier, which makes it impossible for the reaction to proceed at low temperatures (<200 °C). Thus, explorations of other possible motifs of the Ni active site in ZSM-5 zeolite are indispensable. In the present study, we employed the DFT+U method to calculate methane hydroxylation on various motifs of Ni-oxo active species, including [NiO]2+, [Ni2(μ-O)]2+, [Ni2(μ-O)2]2+, and [Ni3(μ-O)3]2+, in the periodic structure of ZSM-5 zeolite. On the basis of agreement between the previously reported experimental and presently calculated activation energies, we suggest the [Ni2(μ-O)2]2+ and [Ni3(μ-O)3]2+ motifs as two possible candidates for the actual structure of active sites in Ni-ZSM-5. Different from [Cu2(μ-O)]2+-exchanged zeolites extensively studied in recent years, [Ni2(μ-O)2]2+- and [Ni3(μ-O)3]2+-ZSM-5 are predicted to activate methane and desorb the formed methanol with low activation and desorption energies, providing a new direction for low-temperature methane hydroxylation with spontaneous methanol desorption.

Graphical abstract: DFT exploration of active site motifs in methane hydroxylation by Ni-ZSM-5 zeolite

Back to tab navigation

Supplementary files

Publication details

The article was received on 11 Jul 2018, accepted on 03 Oct 2018 and first published on 04 Oct 2018


Article type: Paper
DOI: 10.1039/C8CY01441H
Citation: Catal. Sci. Technol., 2018,8, 5875-5885
  •   Request permissions

    DFT exploration of active site motifs in methane hydroxylation by Ni-ZSM-5 zeolite

    M. H. Mahyuddin and K. Yoshizawa, Catal. Sci. Technol., 2018, 8, 5875
    DOI: 10.1039/C8CY01441H

Search articles by author

Spotlight

Advertisements