(438g) Kinetic Modeling Investigation of the Chemical Opportunities of Ethane Reforming in a Nonthermal Plasma, an Electrified Approach to Natural Gas Valorization

Finding electrified routes for the valorization of ethane, usually the second most abundant hydrocarbon in natural gas, has significant environmental benefits and economic incentive. Nonthermal plasma is presented as a possible technology due to its electric-driven nature, mild operating conditions, and demonstrated ability to dehydrogenate ethane. Nonthermal plasmas are generated by applying a strong electric field to a gas in such a way that it becomes partially ionized (~1% ionization) and electrically conductive. This creates a highly reactive environment that is in a non-equilibrium state, with radical, excited, and neutral species near ambient temperatures and free electrons in excess of 10,000 K. Due to the complexities of nonthermal plasma chemistry, most studies using nonthermal plasmas with ethane have focused on demonstrating ethane conversion within a limited range of reaction and plasma conditions. Therefore, we present an investigation of the chemical opportunities within an expanded range of conditions through the use of time-dependent kinetic modeling. We apply a kinetic modeling software (ZDPlasKin) developed for the unique combination of thermally- and electron-excitation-driven chemistry present in nonthermal plasmas. Using a model verified by base-case experimental measurements has allowed us to probe conditions that are often difficult to isolate in an experimental setting. The results of this modeling investigation reveal a landscape of parameter space that expands our understanding of the chemical opportunities of ethane reforming in a nonthermal plasma. We track the product yield and ethane conversion as major outputs of our model, and explore the impact of various inputs including time in plasma, reduced electric field, electron density, and starting gas composition. Within the multi-dimensional results of our modeling, we find opportunities to optimize ethylene and acetylene yields, minimize methane or other less-valuable products yields, maximize ethane conversion, and optimize energy use. For example, limiting the time in plasma to a few micro seconds and increasing the reduced electric field to over 200 Td provides a maximum ethylene yield while keeping methane yield relatively low. A limited technoeconomic analysis based on the possible outcomes of ethane reforming in our model is presented. Our results also highlight opportunities to implement catalyst chemistry to potentially enhance product selectivities.