Shukla, Priyanka Bholanath
(2021)
Modeling of Adsorption of Molecules in Pristine and Defective UiO-66.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Metal-organic frameworks are nanoporous materials that are used for various applications such as gas adsorption, storage, and separations. Our work focuses mainly on the UiO family of Zr-based MOFs, which may be used to capture and destroy chemical warfare agents (CWA) and their simulants. We have studied the adsorption of molecules such as nitrogen, isopropanol, and acetone in UiO-66 with different framework and molecule potentials in order to understand the basic interactions and adsorption mechanism.
The fully coordinated dense structure of UiO-66 has very small pore windows that limit access of larger molecules and thus decreases the adsorption capacity for CWAs. Thus, we have created missing linker defects in Pristine UiO-66 in order to increase accessibility to the pores. Defects may be created experimentally by adding modulators such as acetic acid, formic acid, hydrochloric acid, and other solvents while synthesizing the UiO-66 material where they compete with the organic linkers to form bonds with the Zr6 metal clusters. We have studied the adsorption of molecules in defective UiO-66 with different capping groups such as hydroxide, formate, and acetate and increasing the level of defects. We have studied 4%, 8%, 17%, and 33% missing linker defects. We observe that the saturation uptake increases with the increase in the defect level.
The modeling was done by holding the framework structure rigid in-order to increase the computational efficiency. However, the intrinsic framework flexibility may have a significant impact on the adsorption. To further explore this phenomenon, we have studied the impact of intrinsic framework flexibility on the adsorption of acetone and nitrogen in pristine UiO-66. The modeling was done by performing GCMC simulations on structures generated from NVT-MD snapshots of the empty and finite loaded UiO-66 framework. The results show that introducing framework flexibility increases the adsorption of acetone for both the empty framework and finite loading acetone framework but does not accommodate more nitrogen molecules. This suggests that accurate isotherms require NVT-MD simulations with finite loading of the desired molecule in the framework, followed by modeling of the adsorption isotherm.
Share
| Citation/Export: |
|
| Social Networking: |
|
Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
13 June 2021 |
| Date Type: |
Publication |
| Defense Date: |
19 March 2021 |
| Approval Date: |
13 June 2021 |
| Submission Date: |
4 April 2021 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
73 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Adsorption, RASPA, isotherms, UiO-66, flexible |
| Date Deposited: |
13 Jun 2021 17:30 |
| Last Modified: |
13 Jun 2022 05:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/40509 |
Metrics
Monthly Views for the past 3 years
Plum Analytics
Actions (login required)
 |
View Item |
![[feed]](/images/feed-icon-32x32.png){kind=icon}