APS March Meeting 2024
Monday–Friday, March 4–8, 2024;
Minneapolis & Virtual
Session K64: Electrochemical Energy Conversion
3:00 PM–5:24 PM,
Tuesday, March 5, 2024
Room: 211AB
Sponsoring
Unit:
GERA
Chair: Peter Zapol, Argonne National Laboratory
Abstract: K64.00005 : Gibbs ensemble Monte Carlo simulations for adsorption/desorption of natural gas mixtures in nanoporous materials to assess changes in deliverable energy during cyclic operation*
3:48 PM–4:00 PM
Abstract
Presenter:
Prerna Prerna
(University of Minnesota, Twin Cities)
Authors:
Prerna Prerna
(University of Minnesota, Twin Cities)
J. Ilja Siepmann
(University of Minnesota)
Natural gas (NG) is a cleaner and cheaper fuel with a high energy–to–CO
2 emission ratio. Adsorbed Natural Gas (ANG) storage tanks, packed with a porous adsorbent, have the potential to increase the NG energy density and are being explored extensively for vehicular applications. Even after sweetening, NG is a complex mixture composed of 95% CH
4, smaller fractions of C
2H
6, C
3H
8, CO
2, N
2, and traces of higher hydrocarbons. Hence, a significant challenge in deploying ANG tanks is the poisoning of the adsorbent with the trace components of NG, and the extent of this degradation in deliverable capacity requires further understanding. Previously, mathematical modeling based on data from grand canonical Monte Carlo simulations and ideal adsorption solution theory (IAST) has been utilized to study ANG tank poisoning over multiple cycles of filling and delivery
[1],[2]. However, the assumptions of an infinite reservoir may not reflect the rapid filling required for an ANG storage tank, and IAST would not work for adsorbents with multiple adsorption sites or adsorbates that interact with each other. Therefore, we probe the degradation of the storage capacity using
NpT-Gibbs Ensemble Monte Carlo (GEMC) simulations for an eight-component NG mixture and two approaches to reflect the finite reservoir during filling at the filling pressure. One approach utilizes a large system (both the amount of adsorbent and the number of gas molecules), and the other uses multiple small systems with stochastically determined gas composition. During delivery, the filled adsorbent is brought into contact with an empty gas box at the release pressure. Our results demonstrate the enrichment of higher hydrocarbons and a decrease in CH
4 deliverable capacity after multiple stages of cyclic filling/delivery, but the extent of the decrease in deliverable energy over multiple stages differs significantly from those deduced using the mathematical tank model.
[1] Zhang, H., Deria, P., Farha, O. K., Hupp, J. T. & Snurr, R. Q. Energy Environ. Sci.,2015, 8, 1501–1510.
[2] Wu, Y., Tang, D., Verploegh, R. J., Xi, H., & Sholl, D. S. J. Phys. Chem. C, 2017, 121, 15735–15745.
*Supported by Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Award DE-SC0023454