(511b) Spectroscopic Insights into Plasma-Assisted C1 Conversions and Catalyst Dynamics

Given the critical need to limit our dependence on fossil fuels for energy and chemicals, it is vital to engineer chemical reactions that sustainably produce platform molecules using renewable electricity. One such reaction is the dry reforming of methane (DRM) that converts methane and carbon dioxide into carbon monoxide and hydrogen that is valuable for upgrading to higher order hydrocarbons and liquid oxygenates via Fischer-Tropsch chemistry. While traditional DRM is limited by the activation of thermodynamically stable methane and by catalyst deactivation from adsorbed carbonaceous species, we propose an electrified plasma-assisted catalytic approach, a direct electron process that activates methane and carbon dioxide near ambient temperature and pressure. The incorporation of a catalyst can tailor the selectivity to desired products but can also alter the plasma discharge due to surface interactions. Fundamental understanding of these plasma/catalyst interactions during reaction is one primary challenge facing effective catalyst design. In this work, we demonstrate the use of a dielectric barrier discharge (DBD) plasma jet interfaced with a diffuse reflectance (DR) reaction chamber for operando DR infrared Fourier transform spectroscopy (DRIFTS) to probe relevant surface intermediates during plasma reaction, coupled with packed bed DBD reactor data. We study the plasma-assisted oxidation of carbon monoxide on Pt/Al₂O₃ as a suitable probe reaction for evaluating the strengths and limitations of the jet/cell configuration for mechanistic studies of plasma/catalyst interactions and dynamics. Our work has revealed the ability for certain plasma discharges to oxidize the active metal catalyst and to alter active metal nanoparticle restructuring mechanisms, which has significant impacts on reaction rates. Moreover, the insights gleaned here for CO interactions with Pt and catalyst dynamics under plasma exposure are vital for the understanding and applicability of plasma-assisted catalytic reactors for renewable energy processes.