Mechanistic Insights on the Direct Conversion of Methane into Methanol over Cu/Na–ZSM-5 Zeolite: Evidence from EPR and Solid-State NMR

作者：Jianfeng Wu, Xudong Gao, Longmin Wu, Wei David Wang, Simin Yu, Shi Bai · 发表于：ACS Catalysis · 年份：2019 · DOI：10.1021/acscatal.9b02898 · 被引用次数：41 · 研究领域：Catalytic Processes in Materials Science、Catalysis and Oxidation Reactions、Metal-Organic Frameworks: Synthesis and Applications

The selectively direct conversion of methane to methanol on Cu-exchanged zeolites has attracted a lot of interest because of the abundant availability of methane. A detailed reaction mechanism of the transformation of methane to methanol aimed to improve the catalyst design has been long expected. On the basis of EPR and solid-state NMR studies, we demonstrate that CH 4 activates on the [Cu 2 O] 2+ core of the Cu/Na–ZSM-5 zeolite, producing a ·CH 3 radical and an ·OH radical. The generated methanol molecule, which formed from the combination of ·CH 3 and the ·OH radicals, adsorbs on the Cu + species and forms the copper methoxy species (−Cu–O–CH 3 ) and the −Al–OH group. Through the process of hydration, the copper methoxy species and the adsorbed methanol transform into free methanol. We expect that our mechanistic understanding of the methane to methanol process could pave the way for catalyst design.