Understanding the role of catalyst structure in facilitating sustainable chemical production
- The catalytic transformation of carbon dioxide into syngas and subsequently into higher oxygenate products is one route for meeting the rising global demand for energy and carbon-based consumer products. However, even the most optimized materials have insufficient performance for industrially scaling this process. Because catalyst performance is closely related to its structure, identifying the relationships between the structure of promising catalysts and their behavior under reaction conditions can make it possible to improve and optimize materials that achieve a sustainable future. This dissertation builds this fundamental understanding of catalyst surfaces across several systems of interest. We first bridge catalysis science subdisciplines by investigating a Ni-N-C catalyst, which is known as promising material for electrochemical carbon dioxide reduction to carbon monoxide. We explore the same catalyst for the analogous, thermally driven reverse water-gas shift reaction to generate novel insights on the active site for carbon dioxide reaction in this cross-compatible material. We then apply atomic layer deposition (ALD) of ZnO to uniformly promote Co nanoparticles supported on different materials to induce Co2C formation and understand the effect the support has on cobalt carbide performance. Across three of the four tested supports, we observe different extents of cobalt carbide formation and, subsequently, different oxygenate selectivities during syngas conversion. In contrast, interactions between the ZnO and an aluminum oxide support prevent the ZnO from modifying the Co active phase, highlighting the importance of competing promoter-support interactions that can inhibit the desired catalytic behavior. We finally apply a similar ALD procedure to modify a Rh catalyst with iron oxide ALD and discover that the addition of iron oxide improves methanol and ethanol formation during syngas conversion. In-situ experiments reveal that this change in reactivity is due to the formation of clusters of Fe atoms on the surface of the Rh nanoparticles during catalyst activation, which enhance the intrinsic activity of non-dissociative CO adsorption sites. The insights uncovered through each of the projects were made possible by relying on precise synthesis methods to minimize the potential variables that can impact catalyst performance and on in-situ characterization to fully understand the properties of each material. These tools enable us to develop a stronger fundamental understanding of the intrinsic characteristics of catalysts and can advance our ability to make materials that have sufficient performance for widespread implementation.
|Type of resource
|electronic resource; remote; computer; online resource
|1 online resource.
|Nathan, Sindhu Swami
|Degree committee member
|Degree committee member
|Stanford University, Department of Chemical Engineering
|Statement of responsibility
|Sindhu S. Nathan.
|Submitted to the Department of Chemical Engineering.
|Thesis Ph.D. Stanford University 2022.
- © 2022 by Sindhu Swami Nathan
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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