ChE Seminar Series: Capture and Conversion of CO2 – Towards CO2 Recycling

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02/21/2022
9:35 am-10:30 am
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Juliana Carneiro, Ph.D.
Post-Doctoral Research Fellow at the Georgia Institute of Technology

Title: Capture and Conversion of CO2 – Towards CO2 Recycling

Abstract: Our current global fossil-based economy produces significant environmental, economic, and social challenges. Such complex challenges are the defining issues of our time, pushing society toward stepwise decarbonization of our energy and consumption economy. Ideally, the aim is a more just and reliable economy, with minimal social and environmental burdens and the redistribution of economic and environmental benefits. To this end, a circular carbon economy – which integrates energy, chemical, and waste management sectors – offers an opportunity to rethink our linear model. With the CO2 recycling system playing a central role in this proposed model, the scientific community responds with efforts in R&D to create a suite of CO2 mining and utilization technologies.

In the first part of my talk, I will tackle the electrochemical conversion of CO2 at an elevated temperature regime, using Reversible Solid Oxide Electrochemical Cells (RSOECs). The optimization of the performance of the oxygen and fuel electrodes in these cells has been hindered by the limited understanding of the factors that govern the O2 and CO2 chemistries. As such, I will discuss our efforts toward developing design principles for the identification of optimal electrocatalysts for these electrode reactions. We used a combination of theoretical calculations, controlled synthesis, advanced characterization, and testing to show that the binding energy of atomic oxygen can be used as an activity descriptor for these processes. It was found that a compromise in the oxophilicity of the electrocatalyst was required to achieve optimal activity and stability. Our theory-guided design principles successfully identified: (i) Cobalt-doped La2NiO4 as a highly active material for O2 electrocatalysis, and (ii) Fe, the most oxophilic metal tested, as a highly active metal for CO2 electrochemical reduction. However, Fe exhibited unstable electrochemical behaviors induced by the oxidation of the metal under electrochemical CO2 reduction conditions in SOECs. This phenomenon ratifies the importance of the strength of oxygen binding on the electrocatalyst surface as a descriptor of activity and stability for CO2 electrolysis in SOECs.

In the second part of my talk, I will highlight our work on adsorptive materials for the direct air capture (DAC) of atmospheric CO2. We explore the role of atmospheric humidity as an essential stability parameter for DAC processes employing solid amine adsorbents. We demonstrate this by using prototypical class 1 aminopolymer-type solid sorbents that allow for flexibility in the support use. Sorbent deactivation was investigated by means of several complementary factors, including (i) the relative loss in amine efficiency determined via time-course CO2 sorption, (ii) elemental analysis, and (iii) in situ IR spectroscopy to obtain an understanding of the role of water on the sorbent degradation process. Our findings provide important insights into the relevant parameters that impact the effective design of DAC sorbents and processes for different climatic environments, allowing tailoring of sorbent formulations to overcome the challenges associated with highly varied conditions in which a DAC process must operate.

Bio: Dr. Juliana Carneiro is a postdoctoral research fellow in the School of Chemical Engineering & Biomolecular Engineering at the Georgia Institute of Technology with Professor Christopher W Jones. She received her Ph.D. in Chemical Engineering from Wayne State University in 2019 under the supervision of Prof. Eranda Nikolla. Her research interests lie in developing active, selective, and stable electrocatalysis for electrochemical conversion and separation processes, including the electrochemical recycling/upcycling of post-consumer plastics, the capture and storage of CO2 from oceans, and the capture and conversion of atmospheric CO2. She is the recipient of several awards, including, but not limited to the 2017-2018 Ralph H. Kummler Award for Distinguished Achievement in Graduate Student Research, 2018 Women’s Initiatives Committee’s (WIC) AIChE Travel Award, and the prestigious Student Presentation Awards at the (i) Gordon Research Conference on Catalysis, (ii) the Michigan Catalysis Society.

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