(393a) Molecular Simulation Study of Gas Adsorption and Transport in Room Temperature Ionic Liquid Membranes Supported By Carbon Nanotubes

Development of robust strategies to capture carbon dioxide from flue gas emissions in power plants represents a key step in addressing factors that contribute to climate change. Membranes featuring room temperature ionic liquids (RTILs) have been identified as potentially effective media for capturing carbon dioxide. The very low vapor pressures and tunable nature of RTILs make them attractive media for membranes. The Yu group at the University at Buffalo has recently pursued an approach in which the RTIL is supported by a mesh of single-walled carbon nanotubes (SWCNT). The approach results in a membrane with nano-sized features. The mesh structure potentially provides enhanced mechanical, transport, and selectivity characteristics. In this work, we use molecular simulation tools to study gas adsorption and transport properties within mesh-based RTIL structures, and compare the performance of these systems to bulk RTIL systems. We first discuss generation of a molecular model that aims to capture the essential features of the mesh structure. We next describe the Monte Carlo simulation protocol developed to study gas adsorption. Specifically, we employ a strategy in which the temperature, pressure, numbers of molecules of RTIL and SWCNT, and the activities of relevant gases are fixed. The approach enables us to capture the adsorption characteristics of various model flue gases over a range of pressures and compositions. Finally, we present results for the adsorption and diffusion characteristics of select systems over a broad range of conditions. These characteristics are then linked to the manner in which the RTIL and gases organize within the nano-confined space.