Skip to main content

Creating transformation-stable microstructures through shared crystallographic motifs

Periodic Reporting for period 1 - TRANSFORMERS (Creating transformation-stable microstructures through shared crystallographic motifs)

Reporting period: 2015-05-01 to 2017-04-30

Coal fuels more than 40% of global electricity production, and is responsible for over 40% of global CO2 emissions. Further, coal is widely distributed across the Earth, and demand continues to grow. While we continue to develop alternative and renewable power sources, the capture and sequestration of CO2 from flue gas in fossil fuel power plants and other industrial processes is one viable solution to decrease our CO2 emissions. CO2 can be removed from flue gas by chemical looping, where a material chemically reacts with CO2 and is treated at a later stage to release pure CO2 and regenerate the starting material.
Limestone, CaCO3, is the oldest material to be used for this purpose. However, although limestone is abundant and cheap, the CO2 absorption capacity rapidly decays with use because of undesirable changes to the microstructure. To address the low performance of exisiting materials and enable CO2 looping as a possible technology that can be implemented at scale, new materials must be developed that have high selectivity for CO2, high absorption capacity, durability over many cycles, and reasonably fast kinetics for CO2 absorption and desorption processes.
Developing new high-performance materials is critical to enable next-generation technologies, which are essential to implement large-scale sustainable energy infrastructure and pursue a carbon-neutral footprint. However, breaking out of the known composition space to discover new materials is a difficult challenge in all materials disciplines, and many of the most notable materials classes under investigation today were discovered fortuitously.
Given the difficulty and slow pace with which new material discovery has traditionally occurred, computer-aided materials discovery may now provide the ability to systematically explore chemical whitespace and increase the rate of material discovery and technological progress. Toward this goal, this project has developed and applied computer-aided high-throughput methods to discover new functional materials, which we have prepared and characterized.
Within this larger goal of materials discovery, this project sought to discover new CO2 looping materials that have robust mechanical stability, as determined by their ability to absorb CO2 repeatedly over many cycles. As part of this, this project focused on exploring structural transformations and preparing and investigating novel ternary oxide ceramics designed to be mechanically stable after repeated structural transformations, such as those induced by thermal and CO2 cycling in CO2 capture materials. The new approaches to material design developed and applied in this project will be immediately relevant to many other scientific fields where chemical transformations and mechanical stability are critical, such as battery electrodes, solid oxide fuel cells, solid ion conductors, and catalysts, all of which suffer from performance loss over time due to microstructure changes.

CONCLUSIONS: We have applied a high-throughput prediction and screening method based in first principles calculations (density functional theory, DFT), and have prepared and characterized 12 candidate materials. The material properties agree with calculated properties, and validate this as a useful method to explore new CO2 looping materials.
Using this high-throughput method, we have discovered new materials with CO2 sorption capacities that do not degrade after 25 cycles. One of these materials displays low sorption capacity, but rapid sorption in less than 10 minutes, which may make it suitable for niche applications. Further, we have developed and experimentally validated a high-throughput materials prediction engine using machine learning methods, which may serve as a powerful route to accelerate the rate of new functional materials discovery.
SCREENING, PREPARATION, AND CHARACTERIZATION OF CO2 LOOPING MATERIALS: We used high-throughput screening to select a series of materials, which we have prepared characterized. 12 new materials were studied for their ability to reversibly absorb CO2 over multiple cycles. The material properties agree with calculated properties, and validate this tool as a useful method to explore new CO2 looping materials, as most previous studies have focused on the optimization of well-known systems. This new screening method should be useful to researchers in the field, but should also serve as a model for other functional material families.

FINDINGS: We have developed and applied new high-throughput materials discovery tools, and have discovered 2 new ternary oxide ceramics with CO2 sorption capacities that do not degrade after 25 cycles. One of these materials displays low sorption capacity, but rapid sorption in less than 10 minutes, which may make it suitable for niche applications. This serves as proof there are many possible candidates that may yet serve as viable CO2 looping materials, and will add more possible systems for others to investigate toward this end.

EXPLOITATION/DISSEMINATION: The developments and findings have been published in 6 peer-reviewed journal articles, 4 invited talks, and 1 contributed talk. The central findings concerning the new CO2 looping materials have been written into a manuscript, and will be submitted in the near future for publication in a peer-reviewed journal. We have also performed numerous public outreach activities, including hosting 3-hour workshops (~200 attendees), 6 visits to regional school classrooms (~300 students), 2 open days with 10 activities (~3500 visitors), a front page article in the local newspaper, and 2 feature articles in the Department of Chemistry newsletter, and a collaboration with local artists to sketch the chemistry lab and our work.
The lack of high-performance CO2 looping materials is the critical factor holding back the widespread implementation of carbon capture technology. In particular, most materials suffer from performance degradation after only a few sorption and desorption cycles. This project has developed and applied new materials discovery and screening tools toward the goal of accelerating the materials discovery process. This project has applied these emerging techniques and methods have been applied to the field of CO2 looping materials for the first time, and has discovered two new materials with stable CO2 looping out to 25 cycles with no signs of significant degradation. In addition to specific findings concerning the development of robust looping materials, the effectiveness of these methods may set the stage for future research avenues.