Abstract
We have investigated the effect of molecular shape and charge asymmetry on the translation dynamics of confined hydrocarbon molecules having different shapes but similar kinetic diameters, inside ZSM-5 pores using molecular dynamics simulations. The mean square displacement of propane, acetonitrile, acetaldehyde, and acetone in ZSM-5 exhibit two different regimes – ballistic and diffusive/sub-diffusive. All the molecules except propane exhibit sub-diffusive motion at time scales greater than 1 ps. The intermediate scattering functions reveal that there is a considerable rotational-translational coupling in the motion of all the molecules, due to the strong geometrical restriction imposed by ZSM-5. Overall the difference in shape and asymmetry in charge imposes severe restriction inside the ZSM-5 channels for all the molecules to different extents. Further, the behavior of molecules confined in ZSM-5 in the present study, quantified wherever possible, is compared to their behavior in bulk or in other porous media reported in literature.
| Original language | English |
|---|---|
| Pages (from-to) | 92-102 |
| Number of pages | 11 |
| Journal | Chemical Physics |
| Volume | 516 |
| DOIs | |
| State | Published - Jan 4 2019 |
Funding
This research was sponsored by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences , under contract number DE-AC05-00OR22725 with UT-Battelle, LLC. DRC and SG would like to acknowledge support from the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, Geosciences Program under grant DE-SC0006878.