Yang, Yahui
(2019)
Towards A More Sustainable Chemical Process Industry: Engineering Nanocatalysts for Natural Gas Utilization and Carbon Dioxide Conversion.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Heterogeneous catalysis plays an essential role in the development of more sustainable and resource-efficient chemical processes. However, despite the long history of catalysis, a full understanding of how catalysts work at the nanoscale and hence a rational catalyst design remains largely elusive to-date. In this dissertation, we aim to advance the field by investigating the ability to tailor catalyst selectivity and reactivity through engineering catalyst morphology and composition. To investigate the impact of catalyst morphology on selectivity, we designed Ni@SiO2 core@shell catalysts with well-controlled dimensions to evaluate the impact of pore diffusion on selectivity. We demonstrate preferential diffusion and conversion of H2 in H2-CH4 mixtures due to a “sieving effect” by the microporous SiO2 shell, confirming the utility of core@shell nanocatalysts towards tuning selectivity by tailoring the shell materials. We then extend this approach towards preferential oxidation of H2 in H2-C2H4/C2H6 mixtures and demonstrate the potential of such engineered core@shell materials for oxidative dehydrogenation of alkanes to olefins. Next, we explore the impact of catalyst composition on reactivity by exploring olefin-paraffin separation using metal-organic frameworks (MOFs) with tunable open metal sites, and by designing Cu-based bimetallic nanocatalysts for CO2 adsorption and activation. In the first case, we evaluate the ability of a Cu-exchanged MOF catalyst to engineer adsorption properties, and find strongly preferential adsorption of olefins over paraffins, in excellent agreement with computational predictions. In the second case, we examine the impact of dopants on the reactivity of Cu nanoparticles for CO2 adsorption. We synthesize and characterize mixed CuZr catalysts and confirm computational predictions that this bimetallic system enables strong CO2 adsorption even after oxidation of the Zr phase and hence shows promise for CO2 utilization via hydrogenation. Overall, our work demonstrates that engineering nanocatalysts can enable a systematic evaluation of catalysts functionalities and hence provide guidelines for rational catalyst design for industrial applications.
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| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
10 September 2019 |
| Date Type: |
Publication |
| Defense Date: |
24 April 2019 |
| Approval Date: |
10 September 2019 |
| Submission Date: |
17 June 2019 |
| Access Restriction: |
5 year -- Restrict access to University of Pittsburgh for a period of 5 years. |
| Number of Pages: |
146 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical and Petroleum Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Engineering nanocatalysts, natural gas conversion, CO2 utilization |
| Date Deposited: |
10 Sep 2019 18:26 |
| Last Modified: |
10 Sep 2019 18:26 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/36947 |
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