Increased availability of light hydrocarbons from shale gas raises the interest of methane, the main component of natural gas, as a C1 feedstock for the chemical industry. Copper-exchanged zeolite have been attracted a great attention due to their activity in the selective oxidation of methane at temperature below 200 ○C. Among the variety of zeolite topologies, MOR with its specific structure of straight 12-MR channel with intersecting 8-MR side pockets have shown high methanol productivity. Dimeric and trimeric Cu-oxo species with Al pairs at the 8-MR side pockets of MOR have shown to be the most favorable active sites in Cu-MOR. Recently, Dyballa et al. reported an increased activity of methane oxidation in the presence of higher concentrations of extraframework aluminum (EFAl) on Cu-MOR. However, the exact nature of this interaction of EFAl with active Cu species, and the mechanism of this activity enhancement is still not known. In this talk, I will present structural properties and composition of active sites of Cu-Al-oxo clusters on Cu-MOR obtained from ab initio molecular dynamics (AIMD), simulated ensemble averaged Cu K- and L3-edge X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra using AIMD trajectories along with experimental results. This talk will demonstrate the critical importance of including both statistic and dynamic configurational complexity in our models for interpreting XAS spectra.

Cu-Al-oxo clusters on mordenite: combined study of ab initio molecular dynamics, ensemble averaged XAS simulations, and experiments

ACS Spring Meeting 2021

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