new findings

Rice University and UH labs team up to improve emerging carbon capture technique

New research from Rice and UH has helped boost the lifespan of CO2RR systems, a newer technology used for carbon capture. Photo via htxenergytransition.org

A team of researchers led by professors from two Houston universities has discovered new methods that help stabilize an emerging technique known as carbon dioxide reduction reaction, or CO2RR, that is used for carbon capture and utilization processes.

The team led by Rice University’s Haotian Wang, associate professor in chemical and biomolecular engineering, and Xiaonan Shan, associate professor of electrical and computer engineering at University of Houston, published its findings in a recent edition of the journal Nature Energy.

CO2RR is an emerging carbon capture and utilization technique where electricity and chemical catalysts are used to convert carbon dioxide gas into carbon-containing compounds like alcohols, ethylene, formic acids or carbon monoxide, according to a news release from Rice. The result can be used as fuels, chemicals or as starting materials to produce other compounds.

The technology is used in commercial membrane electrode assembly (MEA) electrolyzers to convert carbon dioxide into valuable compounds, but the technology isn’t perfected. A significant challenge in CO2RR technology has been the accumulation of bicarbonate salt crystals on the backside of the cathode gas diffusion electrode and within the gas flow channels. The salt precipitates block the flow of carbon dioxide gas through the cathode chamber, which reduce the performance and can cause a failure of the electrolyzers.

The goal in the study was to understand why and how bicarbonate salts form during this reaction. The Rice and UH teams worked together using operando Raman spectroscopy, which is a technique that allows researchers to study the structure of materials and any precipitates that adhere to them while the device is functioning.

“By utilizing operando Raman spectroscopy and optical microscopy, we successfully tracked the movement of bicarbonate-containing droplets and identified their migration pattern,” Shan said in the release. “This provided us the information to develop an effective strategy to manage these droplets without interrupting system stability.”

Next, the team worked to prevent the salt crystals from forming. First, they tested lowering the concentration of cations, like sodium or potassium, in the electrolyte to slow down the salt formation. This method proved to be effective.

They also coated the cathode with parylene, a synthetic polymer that repels water, like Teflon, which also notably improved the stability of the electrolyzer and prevented salt accumulation.

“Inspired by the waxy surface of the lotus leaf which causes water droplets to bead up and roll off, carrying off any dirt particles with it and leaving the leaf’s surface clean, we wondered if coating the gas flow channel with a nonstick substance will prevent salt-laden droplets from staying on the surface of the electrodes for too long and, therefore, reduce salt buildup.” Wang said in the release.

According to Wang, these relatively simple discoveries can extend the operational lifespan of CO2RR systems from a few hundred hours to over 1,000 hours.

The findings also have major implications for commercial applications, Shan added.

“This advancement paves the way for longer-lasting and more reliable (CO2RR) systems, making the technology more practical for large-scale chemical manufacturing,” Shan said in the release. “The improvements we developed are crucial for transitioning CO2 electrolysis from laboratory setups to commercial applications for producing sustainable fuels and chemicals.”

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A View From HETI

1PointFive, a subsidiary of Oxy, was granted the first-ever EPA permits for its large-scale carbon capture and sequestration facility in Texas. Photo via 1pointfive.com

Houston’s Occidental Petroleum Corp., or Oxy, and its subsidiary 1PointFive announced that the U.S Environmental Protection Agency approved its Class VI permits to sequester carbon dioxide captured from its STRATOS Direct Air Capture (DAC) facility near Odessa. These are the first such permits issued for a DAC project, according to a news release.

The $1.3 billion STRATOS project, which 1PointFive is developing through a joint venture with investment manager BlackRock, is designed to capture up to 500,000 metric tons of CO2 annually and is expected to begin commercial operations this year. DAC technology pulls CO2 from the air at any location, not just where carbon dioxide is emitted. Major companies, such as Microsoft and AT&T, have secured carbon removal credit agreements through the project.

The permits are issued under the Safe Drinking Water Act's Underground Injection Control program. The captured CO2 will be stored in geologic formations more than a mile underground, meeting the EPA’s review standards.

“This is a significant milestone for the company as we are continuing to develop vital infrastructure that will help the United States achieve energy security,” Vicki Hollub, Oxy president and CEO, said in a news release.“The permits are a catalyst to unlock value from carbon dioxide and advance Direct Air Capture technology as a solution to help organizations address their emissions or produce vital resources and fuels.”

Additionally, Oxy and 1PointFive announced the signing of a 25-year offtake agreement for 2.3 million metric tons of CO2 per year from CF Industries’ upcoming Bluepoint low-carbon ammonia facility in Ascension Parish, Louisiana.

The captured CO2 will be transported to and stored at 1PointFive’s Pelican Sequestration Hub, which is currently under development. Eventually, 1PointFive’s Pelican hub in Louisiana will include infrastructure to safely and economically sequester industrial emissions in underground geologic formations, similar to the STRATOS project.

“CF Industries’ and its partners' confidence in our Pelican Sequestration Hub is a validation of our expertise managing carbon dioxide and how we collaborate with industrial organizations to become their commercial sequestration partner,” Jeff Alvarez, President of 1PointFive Sequestration, said in a news release.

1PointFive is storing up to 20 million tons of CO2 per year, according to the company.

“By working together, we can unlock the potential of American manufacturing and energy production, while advancing industries that deliver high-quality jobs and economic growth,” Alvarez said in a news release.

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