Peng, Xi
(2017)
FIRST-PRINCIPLES STUDY OF CO2 REDUCTION ON MO2C.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Periodic Density Functional Theory (DFT) calculations are widely used to study the interactions between reagents and catalysts, as well as to understand the reaction mechanisms occurring on the catalyst surface. In this work, we investigated the CO2 adsorption, activation and reduction to CO on (1) pristine, (2) K-promoted, and (3) oxygen-covered (001) orthorhombic Molybdenum carbide (β-Mo2C) surfaces. We calculated the CO2 interaction with both surface terminations of β-Mo2C, Mo-terminated and C-terminated, and we found a thermodynamically feasible chemisorption and dissociation of CO2 on the Mo-terminated surface. The activation energy for CO2 dissociation on β-Mo2C (001) surface was found to be 16.8 kcal/mol. The presence of surface promoter atom, potassium (K), enhanced the binding of CO2, and lowered the activation barrier for CO2 dissociation from 16.8 kcal/mol to 14.0 kcal/mol. Due to the high oxophilicity of the (001) Mo2C surface, we further investigated the CO2 adsorption and dissociation profile on O-covered (001) Mo2C (simulating experimental conditions), and we found that CO2 can still adsorb and dissociate on β-Mo2C (001) surface, even in the presence of surface oxygen up to 0.5ML. As O-coverage increases, the activation barrier for CO2 dissociation increases. Our results rationalize a series of experimental observations.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
| Title | Member | Email Address | Pitt Username | ORCID |
|---|
| Thesis Advisor | Mpourmpakis, Giannis | | | | | Committee Member | Johnson, J. Karl | | | | | Committee Member | Veser, Goetz | | | |
|
| Date: |
25 September 2017 |
| Date Type: |
Publication |
| Defense Date: |
14 June 2017 |
| Approval Date: |
25 September 2017 |
| Submission Date: |
20 June 2017 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
51 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical and Petroleum Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
CO2 reduction, metal carbide, catalysis |
| Date Deposited: |
25 Sep 2017 19:21 |
| Last Modified: |
25 Sep 2017 19:21 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/32501 |
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