¹³C MAS NMR Study of Ethane Aromatization and Oxidation on In-Modified BEA Zeolite

In this work, the pathways of ethane transformation on the In-modified BEA zeolite have been investigated by solid-state NMR spectroscopy. It has been found that the primary intermediate formed from ethane is an ethylindium surface species, which is further transformed to ethene by dehydrogenation or oxidized to acetaldehyde and acetate. Ethene undergoes oligomerization and further aromatization to give monoaromatic hydrocarbons. It has been shown that light alkanes are not formed alongside aromatic compounds, indicating that aromatization predominantly proceeds with the assistance of indium sites rather than Brønsted acid sites. The dissociation of the C–C bond in ethane has also been observed yielding formate and carbon dioxide, as well as enabling the formation of methylated benzenes. It is demonstrated that the addition of molecular oxygen provides indium-oxo cationic site regeneration which results in higher ethane conversion to ethylindium species and C1–C2 oxygenate compounds. The results obtained unravel the potential of zeolites modified with indium-oxo cationic sites for the effective utilization of natural gas.