Probing the Interface of Plasma, Metal, and Catalyst Support in Plasma-Assisted Dry Methane Reforming on Pt-Based Catalysts

Abstract

Abstract Nonthermal plasma (NTP)-assisted dry methane reforming (DMR) on supported metal catalysts has emerged as a promising method for sustainable, electrified conversion of methane (CH4) and carbon dioxide (CO2) into carbon monoxide (CO) and hydrogen (H2), which are valuable chemical/fuel precursors and energy carriers. NTP-assisted DMR has been reported to enhance reaction rates and reduce catalyst deactivation relative to purely thermal operation. However, the complex interactions between the plasma, metal nanoparticles, and catalyst support under reaction conditions complicate mechanistic interpretation and limit informed catalyst design. Here, plasma-assisted DMR on platinum (Pt) nanoparticles supported on alumina (Al2O3), silica (SiO2), and zeolite 3A was investigated in a coaxial packed-bed dielectric barrier discharge (DBD) reactor to increase understanding of how the plasma, metal, and support interact to govern activity, selectivity, and catalyst stability. The plasma enhanced DMR turnover rates, altered selectivity among DMR, reverse water–gas shift (RWGS), and direct coupling of methane (DCM) pathways as indicated by CO, H2, water (H2O), and ethane (C2H6) formation rates, and reduced the apparent activation barriers. The extents of all these plasma-induced changes were impacted by the catalyst identity. Properties of the support (e.g., basic site density and dielectric constant) affected the plasma power and catalytic performance, and the Pt nanoparticle size impacted the plasma and product selectivity. Post-reaction characterization and extracted deactivation rate constants revealed support-dependent catalyst stability, including coke formation and Pt restructuring, with minimal sintering on Al2O3, significant agglomeration on 3A after plasma exposure, and reduced deactivation of Pt/SiO2 under plasma-assisted conditions relative to thermal conditions. These results provide insight into the interplay of plasma, metal nanoparticles, and support in NTP-assisted DMR, with implications for informed catalyst design and process optimization in similar plasma-assisted catalytic C1 upgrading systems.