Exploring Low-Temperature Dehydrogenation at Ionic Cu Sites in Beta Zeolite To Enable Alkane Recycle in Dimethyl Ether Homologation

Cu-based catalysts containing targeted functionalities including metallic Cu, oxidized Cu, ionic Cu, and Brønsted acid sites were synthesized and evaluated for isobutane dehydrogenation. Hydrogen productivities, combined with operando X-ray absorption spectroscopy, indicated that Cu­(I) sites in Cu/BEA catalysts activate C–H bonds in isobutane. Computational analysis revealed that isobutane dehydrogenation at a Cu­(I) site proceeds through a two-step mechanism with a maximum energy barrier of 159 kJ/mol. These results demonstrate that light alkanes can be reactivated on Cu/BEA, which may enable re-entry of these species into the chain-growth cycle of dimethyl ether homologation, thereby increasing gasoline-range (C5+) hydrocarbon yield.