Zhang, Bo
(2013)
COMPUTATIONAL STUDY OF CO2 CAPTURE AND GAS ADSORPTION ON SURFACES.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The structural and thermodynamic properties of MHCO3 (M = Li, Na, K) were investigated with density functional theory (DFT). The most probable crystal structure for LiHCO3, which has not been observed experimentally, was predicted from first principles. The stability of LiHCO3 has also been predicted as a function of certain temperature and the partial pressures of CO2 and H2O. The phase diagrams and possible CO2 capture reactions as a function of temperature and the partial pressures of CO2 and H2O were calculated from total energies from DFT and free energies from lattice dynamics for M-C-O-H systems.
Different exchange-correlation functionals (PW91, PBE, PBEsol, TPSS, and revTPSS) were used to compute van't Hoff plots, which describe the reaction equilibrium as a function of the partial pressures of CO2 and H2O as well as temperature, for TMO and TM(OH)2, where TM = Mn, Ni, Zn, and Cd. The PBEsol functional gives better equilibrium properties due to a partial cancellation of errors in the enthalpies of formation. We have identified all CO2 capture reactions that lie on the Gibbs free energy convex hull as a function of temperature and the partial pressures of CO2 and H2O for TMO and TM(OH)2 systems.
We have constructed a reaction pathway for tetrabutylphosphonium glycinate ([P(C4)4][Gly]) reacting with CO2. The reaction has two barriers, as computed from nudged elastic band calculations. A ReaxFF force field was developed based on the reaction pathway and other relevant bond, angle, torsion angle energies as well as equation of state of [P(C4)4][Gly]. The force field has been validated and used for large-scale molecular dynamics simulations to study the thermophysical properties of the [P(C4)4][Gly]/CO2 system.
Weakly bound molecular O2 on TiO2(110) surface has been studied using DFT with van der Waals (vdW) corrections. The potential energy surface of O2 on TiO2(110) was constructed and the adsorption energy was found to be dominated by vdW contributions in most situations. The calculated vibrational frequency of the adsorbed O2 molecule was found to be close to recently experimental IR measurements. The calculated IR intensities were found to be in qualitative agreement with experiments. Our calculations show that the appearance of IR modes for O2 adsorbed on TiO2(110) are due to the charge transfer within the O2 molecule caused by the electric field of the TiO2 surface.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
31 January 2013 |
| Date Type: |
Publication |
| Defense Date: |
26 October 2012 |
| Approval Date: |
31 January 2013 |
| Submission Date: |
26 November 2012 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
131 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
CO2 capture, alkali and transition metal compounds, ionic liquid, density functional theory, ReaxFF force field, O2 adsorption, TiO2(110) surface, thermodynamics |
| Date Deposited: |
31 Jan 2013 21:34 |
| Last Modified: |
15 Nov 2016 14:06 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/16112 |
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