(79h) Factors Affecting Catalytic Performance in the Presence of Non-Thermal Plasmas

Plasmas have been used to enhance the selectivity, activity, and product yields in a variety of chemical reactions. Additionally, plasmas can be generated in the presence of a catalyst to assist in the dissociation or activation of molecules to promote subsequent reactions. A highly sought-after goal of plasma-assisted catalysis is the ability to control the reaction selectivity by tuning the plasma environment or plasma-catalyst interaction. We have been particularly interested in the use of non-thermal plasmas in the catalytic production of syn-gas from methane/carbon dioxide and the production of ammonia from nitrogen/hydrogen. Specifically, this presentation will focus on 1) the reaction regime where catalyst-plasma interactions are observed for the two reactions highlighted above, 2) the various catalyst-plasma interactions observed, and 3) the role of the plasma in enhancing reaction efficiency. For the plasma-assisted dry reforming of methane, we have performed detailed kinetic experiments to determine the catalytic consequences when the partial pressures of the reactants, flow rates, reaction temperatures, and plasma power are varied. From a variety of kinetic and control experiments, an energy barrier was obtained from a relationship between the reaction rate constant and input power (≤ ~20 kJ/mol), which was lower than the ~70 kJ/mol obtained for thermal catalysis on Ni/Al₂O₃. Recent results for the ammonia synthesis reaction in the presence of non-thermal plasmas will also be discussed.