Efficient catalysts of surface hydrophobic Cu-BTC with coordinatively unsaturated Cu(I) sites for the direct oxidation of methane

Wencui Li; Zhi Li; Hang Zhang; Pengxiao Liu; Zean Xie; Weiyu Song; Baijun Liu; Zhen Zhao

doi:10.1073/pnas.2206619120

Efficient catalysts of surface hydrophobic Cu-BTC with coordinatively unsaturated Cu(I) sites for the direct oxidation of methane

Proc Natl Acad Sci U S A. 2023 Mar 7;120(10):e2206619120. doi: 10.1073/pnas.2206619120. Epub 2023 Feb 27.

Authors

Wencui Li¹, Zhi Li¹, Hang Zhang², Pengxiao Liu¹, Zean Xie², Weiyu Song¹, Baijun Liu¹, Zhen Zhao^{1

2}

Affiliations

¹ State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China.
² Institute of Catalysis for Energy and Environment, College of Chemistry and Chemical Engineering, Shenyang Normal University, Shenyang, Liaoning 110034, P. R. China.

Abstract

Selective oxidation of methane to organic oxygenates over metal-organic frameworks (MOFs) catalysts at low temperature is a challenging topic in the field of C1 chemistry because of the inferior stability of MOFs. Modifying the surface of Cu-BTC via hydrophobic polydimethylsiloxane (PDMS) at 235 °C under vacuum not only can dramatically improve its catalytic cycle stability in a liquid phase but also generate coordinatively unsaturated Cu(I) sites, which significantly enhances the catalytic activity of Cu-BTC catalyst. The results of spectroscopy characterizations and theoretical calculation proved that the coordinatively unsaturated Cu(I) sites made H₂O₂ dissociative into •OH, which formed Cu(II)-O active species by combining with coordinatively unsaturated Cu(I) sites for activating the C-H bond of methane. The high productivity of C1 oxygenates (CH₃OH and CH₃OOH) of 10.67 mmol g_cat.^-1h^-1 with super high selectivity of 99.6% to C1 oxygenates was achieved over Cu-BTC-P-235 catalyst, and the catalyst possessed excellent reusability.

Keywords: Cu-BTC; catalysts; coordinatively unsaturated Cu(I) sites; selective oxidation of methane; surface hydrophobic coating.

Abstract

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