Methane activation on Ga‐modified ZSM‐5 zeolites (Ga/ZSM‐5) was studied by solid‐state NMR spectroscopy. Two types of Ga species, namely highly dispersed oxides and cationic Ga species, were determined by ⁷¹Ga QCPMG NMR. The activation of methane on Ga/ZSM‐5 was explored by using ¹³C and ¹H MAS NMR. Four types of Ga‐CH₃ species along with Ga‐OH groups were observed on Ga/ZSM‐5, evidencing different pathways for heterolytic cleavage of C−H bond of methane. Two‐dimensional (2D) ¹H‐¹H correlation NMR experiments provide detailed information on the location and local environment of the Ga‐CH₃ species by correlating the protons in Ga‐CH₃ with those in Ga‐OH and other hydroxyls on zeolite. The structures of different Ga‐CH₃ species were further determined by 2D ¹H‐¹³C heteronuclear correlation NMR experiments, which were supported by theoretical calculations. The activation routes of C−H bond in methane were proposed on Ga/ZSM‐5 zeolite.

Link:https://chemistry-europe.onlinelibrary.wiley.com/doi/full/10.1002/cctc.202000650