InterPore2021

Examining the Structure of Supercritical CO2 using X-ray Raman Spectroscopy and Atomistic Scale Modeling

3 Jun 2021, 18:30

15m

Oral Presentation (MS13) Fluids in Nanoporous Media MS13

Speaker

Ms Priyanka Muhunthan

Description

Carbon capture and sequestration (CCS) involves the injection of supercritical carbon dioxide into tight rock formations such as shale. Previous studies have shown that such nanoconfinement leads to changes in phase behavior, including reduction in critical point and changes in interfacial surface tension. In this work, X-ray Raman Spectroscopy (XRS) is used to examine the structural changes of supercritical CO2 during phase-transition. We combine XRS measurements, molecular dynamics simulations, and first principles density functional theory (DFT) calculations to characterize the local electronic structure of CO2 near the critical point and crossing the Widom line. We observe clear differences in the spectral fingerprint of the oxygen K-edge spectra of liquid CO2, which is supported by DFT-based calculations. To understand the behavior of nanoconfined supercritical CO2, these experimental measurements are complemented by molecular-dynamics simulation to explain the observations and examine the molecular structure during the phase-transition.