Chi, Hao
(2019)
Fundamental Study of Cu-Based Catalysts for Methanol Oxidation.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
This is the latest version of this item.
Abstract
Heterogeneous catalysis plays a crucial role in addressing clean energy and chemical production needs. Currently, we are still far from controlling the nanoscale structures, metal-support interfaces, and chemical states of heterogeneous catalysts via rational catalyst design. In this dissertation, we aimed to experimentally identify active phases and active sites of Cu-based catalysts, which is the most widely used class of heterogeneous catalyst in the methanol industry. We first evaluate the Cu oxidation states present in Cu/ZnO catalysts in partial oxidation of methanol (POM) under different reaction conditions, finding a strong dependency between Cu oxidation state and POM H2 selectivity. No such dependency was observed between POM CO2 selectivity and Cu oxidation state, rather CO2 selectivity only depended on O2 partial pressure. In the second part of the thesis, we identify the active sites of Cu2O nano-islands during MeOH induced reduction using Environmental Transmission Electron Microscopy (ETEM). We observed a two-stage reductive shrinking mechanism for Cu2O nano-islands on Cu(100) facets featuring a transition from anisotropic to isotropic shrinking which is caused by preferential adsorption of methanol molecules on Cu(100) step edges rather than flat Cu(100) terrace. Finally, the third part of the thesis examines the atomic scale dynamics of Cu2O nano-island and its interface with Cu during MeOH induced reduction. We observed interfacial transformations from Cu2O to Cu facilitated by preferential reactions at the perimeters of Cu2O islands, which could alter interfacial reactivity under MeOH and lead to island tilting resulting from the accumulation of Cu at Cu/Cu2O interface. Overall, this project yielded key insights on identifying the active phases and sites of Cu-based catalysts during MeOH oxidation which will enrich the fundamental understanding towards selective designing heterogeneous catalysts in the future.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
24 January 2019 |
| Date Type: |
Publication |
| Defense Date: |
16 July 2018 |
| Approval Date: |
24 January 2019 |
| Submission Date: |
3 July 2018 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Number of Pages: |
148 |
| 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: |
copper-based catalysts, heterogeneous catalysis, methanol oxidation, in situ TEM, solid-gas reaction |
| Date Deposited: |
24 Jan 2019 15:38 |
| Last Modified: |
24 Jan 2024 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/35666 |
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Fundamental Study of Cu-Based Catalysts for Methanol Oxidation. (deposited 24 Jan 2019 15:38)
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