Bioinspired Cu(II) Defect Sites in ZIF-8 for Selective Methane Oxidation

Ying Yang, Siriluk Kanchanakungwankul, Suman Bhaumik, Qing Ma, Sol Ahn, Donald G. Truhlar, Joseph T. Hupp

    Research output: Contribution to journalArticlepeer-review

    3 Scopus citations

    Abstract

    Activating the C-H bonds of alkanes without further oxidation to more thermodynamically stable products, CO and CO2, is a long-sought goal of catalytic chemistry. Inspired by the monocopper active site of methane monooxygenase, we synthesized a Cu-doped ZIF-8 metal-organic framework with 25% Cu and 75% Zn in the nodes and activated it by heating to 200 °C and dosing in a stepwise fashion with O2, methane, and steam. We found that it does oxidize methane to methanol and formaldehyde. The catalysis persists through at least five cycles, and beyond the third cycle, the selectivity improves to the extent that no CO2 can be detected. Experimental characterization and analysis were carried out by PXRD, DRUV−vis, SEM, and XAS (XANES and EXAFS). The reaction is postulated to proceed at open-coordination copper sites generated by defects, and the mechanism of methanol production was explicated by density functional calculations with the revMO6-L exchange-correlation functional. The calculations reveal a catalytic cycle of oxygen-activated CuI involving the conversion of two molecules of CH4 to two molecules of CH3OH by a sequence of hydrogen atom transfer reactions and rebound steps. For most steps in the cycle, the reaction is more favored by singlet species than by triplets.

    Original languageEnglish (US)
    Pages (from-to)22019-22030
    Number of pages12
    JournalJournal of the American Chemical Society
    Volume145
    Issue number40
    DOIs
    StatePublished - Oct 11 2023

    Bibliographical note

    Publisher Copyright:
    © 2023 American Chemical Society.

    PubMed: MeSH publication types

    • Journal Article

    Fingerprint

    Dive into the research topics of 'Bioinspired Cu(II) Defect Sites in ZIF-8 for Selective Methane Oxidation'. Together they form a unique fingerprint.

    Cite this