Advancing Catalytic Dehydrogenation and Coupling of Light Hydrocarbons Via Nonthermal Plasma

Plasma catalysis offers a promising pathway for the decarbonization of natural gas and greenhouse gas valorization, leveraging renewable electricity to drive chemical transformations under mild conditions. However, fundamental knowledge gaps remain in plasma-catalyst interactions, limiting the optimization and scalability of these processes. This dissertation explores key aspects of plasma-surface coupling, emphasizing innovative experimental approaches to characterize and manipulate plasma-driven reactions. A custom-designed plasma cell was developed to enable simultaneous surface, plasma-phase, and gas-phase analysis using Fourier transform infrared spectroscopy (FTIR), optical emission spectroscopy, and mass spectrometry. This system provided direct evidence of plasma-induced surface transformations, including selective oxidation of amine-functionalized SBA-15 and the evolution of NOx species on a Pt-surface in an air discharge. Additionally, nonthermal plasma was shown to induce strong metal-support interactions (P-SMSI) in platinum-niobia catalysts at sub-ambient temperatures, enhancing selectivity for propane dehydrogenation. Time-resolved CO adsorption FTIR spectroscopy indicated P-SMSI forms via a mechanism of diffusion-controlled surface migration at low temperatures, revealing a departure from the thermal mechanism. This launched a kinetic evaluation into the induction and reversal of P-SMSI at both elevated and sub-ambient temperatures, providing insight into how temperature affects nonthermal plasma-catalyst interactions. Further, plasma-driven activation of ethane was investigated to address carbon growth challenges, demonstrating the formation of uniform “diamond-like” carbon microstructures on the metal surface of the electrode. By modulating plasma parameters and limiting access to metal surfaces, the carbon nucleation in the reactor was controlled and even avoided entirely under certain configurations. Collectively, these studies provide new insights into plasma-surface interactions, unlocking strategies to enhance reaction selectivity, stability, and sustainability for future plasma-driven chemical technologies.