Performance of Activated Carbons Derived from Date Seeds in CO₂ Swing Adsorption Determined by Combining Experimental and Molecular Simulation Data

The ability to experimentally control the structural features of activated carbons (ACs), combined with current advances in modeling carbon-based materials at the atomic level, allows one to build predictive models for the process design of novel applications. This contribution is devoted to molecular simulations of CO₂ in ACs, starting from building the atomistic adsorbent model, validated with experimental results, and simulating its application for CO₂ capture and separation by adsorption. Single components and competitive adsorption data of binary mixtures from different industrial streams (e.g., CO₂/N₂ and CO₂/CH₄) were obtained by Grand Canonical Monte Carlo (GCMC) simulations, performed under typical operating conditions for the separation of streams associated with post-combustion and natural gas sweetening. We employed a previously published modeling technique to represent ACs, based on packing noninterconnected functionalized fragments of carbon sheets with surface heterogeneities. GCMC simulations were first used to calculate adsorption isotherms and isosteric heats to analyze the performance of the ACs for CO₂ capture. Predicted process parameters such as working capacities and purities were evaluated and complemented with energetic performance for swing adsorption processes, with and without preadsorbed traces of water. Results show that the presence of preadsorbed water does not significantly affect the adsorption performance, but it influences the energy consumption of the process. Furthermore, a small amount of water can improve the CO₂ capture performance in some specific cycles at low pressures.