(433d) Molecular Simulation of Carbon Dioxide Transport in Carbons—Highlighting the Importance of Potential and Structural Models

Understanding carbon dioxide (CO₂) adsorption and transport is crucial to the development of successful carbon capture and storage technologies, in addition to assisting in enhancing gas recovery from the natural systems such as coal and shale. Non-equilibrium molecular dynamics (NEMD) simulations were conducted to investigate pore entrance effects on transport through carbon pores. Pure and hydroxyl-functionalized slit and step pores are considered, to investigate pore entrance effects and tradeoffs between pore size, chemistry, capacity, and transport.  To determine the significance of electrostatic interactions on CO₂ transport through pore entrances, simulations were conducted using potential models of varying levels of sophistication. The relative importance of 1) CO₂ geometry and flexibility, 2) electrostatic interactions, and 3) pore surface chemistry is investigated. 

The transport investigations of CO₂ through carbon pores suggest that fluid density, diffusivity, and permeability are sensitive to the potential model used to describe molecular interactions, pore size, pore geometry, and surface chemistry. The differences in capacity and dynamic properties between the step and slit cases show the importance of investigating transport using models that account for different types of mass-transfer resistance. The current work highlights the importance of the potential and structure models in molecular simulations of adsorption and dynamics. These fundamental studies indicate the significance of molecular-scale phenomena in carbon dioxide transport in the confined spaces for carbon capture and sequestration applications.