Ion- Exchange of Zeolitic Brønsted Acid Sites with Metal Cations Influences the Hydrocarbon Pools (HCP) during Tandem CO2 Hydrogenation

We demonstrate that the exchange of zeolitic Brønsted acid sites (BAS) with cations from metal-oxides plays a pivotal role in the propagation of hydrocarbon pools (HCP) during CO2 hydrogenation. We estimated the likelihood of cationic species migration from different oxides-In2O3, ZnZrOx, Cr2O3 and their exchange with BAS by computing metal vacancy formation energies. Accordingly, we integrated metal-oxides and SAPO-34 at nanoscale proximity (~1400 nm), to probe the propensity of the cations to exchange with BAS. To assess the influence of ion-exchange on HCP, we measured propylene-to-ethylene (indicates relative propagation of olefin-to-aromatic cycles) and paraffin-to-olefins ratios, which revealed that Inδ+ species inhibited HCP propagation, Znδ+ species enhanced hydrogen transfer, and Crδ+ species did not influence HCP. Combining reactivity data with ammonia temperature programmed desorption, occluded hydrocarbon analysis, 13C solid-state nuclear magnetic resonance (ssNMR) and X-ray photoelectron spectroscopy analysis (XPS), we provide insights into the influence of ion-exchanged species on HCP for rational integration of bifunctional catalysts.