Oregon State University scientists have filed a patent application for a new carbon capture material that turns water in factory flue emissions from a problem into an advantage.
The study involving metal-organic frameworks, or MOFs, is important because industrial activities, among them burning fossil fuels for energy, account for a significant percentage of the carbon dioxide in the Earth's atmosphere. In the United States, 30% of total greenhouse gas emissions are from industry, according to the Environmental Protection Agency.
Published in Angewandte Chemie, the findings show that the new MOF, dubbed BVR-X, essentially directs water and carbon dioxide to different regions inside its pores, preventing water from blocking the places where carbon dioxide is captured.
"This internal organization helps the material work under conditions that more closely resemble real industrial emissions," said Kyriakos Stylianou, professor of chemistry in the OSU College of Science.
MOFs are crystalline materials made up of positively charged metal ions surrounded by organic "linker" molecules known as ligands. The metal ions make nodes that bind the linkers' arms to form a repeating structure that looks something like a cage; the structure has nanosized pores that adsorb gases, similar to a sponge.
MOFs can be designed with a variety of components, which determine the MOF's properties, and there are millions of possible MOFs, Stylianou said. More than 100,000 of them have been synthesized by chemistry researchers, and the properties of hundreds of thousands of others have been predicted.
"The capture of CO2 is critical for meeting net-zero emission targets," said Stylianou, who directs OSU's Materials Discovery Laboratory, known as the MaD Lab. "MOFs have shown a lot of promise because of their porosity and their structural versatility."
Carbon dioxide, a greenhouse gas, results from burning fossil fuels and is one of the primary causes of a warming climate.
Facilities that filter carbon from the air are beginning to spring up around the globe - the world's largest opened in 2024 in Iceland - but they're not ready to make a large dent in the worldwide emissions problem, Stylianou notes. In a year, the Iceland plant can draw out carbon dioxide in quantities similar to the annual emissions of about 7,200 cars.
However, technologies for mitigating carbon dioxide at the point of entry into the atmosphere, such as a factory, are comparatively well developed. One of those technologies involves MOFs that can intercept carbon dioxide molecules through adsorption as flue gases make their way through smokestacks.
Dealing with the water portion of smokestack gases, though, greatly complicates removing the carbon dioxide, Stylianou said. Many MOFs that have shown carbon capture potential lost their effectiveness in humid, real-world flue conditions.
Flue gases can be dried, but that adds significant expense to the carbon dioxide removal process, enough to make it nonviable for industrial applications.
"Water usually makes capturing carbon dioxide more difficult," he said. "Our new material does something unusual: It responds to water by changing in a way that lets it keep capturing CO2 effectively even under very humid conditions."
Testing showed that the MOF efficiently captured the greenhouse gas from a highly humid stream containing just 4% carbon dioxide - conditions relevant to emissions from natural gas combustion, "where separating a small amount of CO2 in the presence of substantial water is particularly challenging," said Stylianou.
"And the material can be regenerated and reused, maintaining performance through dozens of capture-and-release cycles and tolerating demanding conditions," he added. "Those are important qualities for practical carbon-capture technologies."
Collaborating with Stylianou were MaD Lab members Ankit Yadav, Emmanuel Musa and Andrzej Gładysiak; Micah Hickethier, Chun-Wai Chang and Kai Shen Choong of the Oregon State College of Engineering; and scientists from the University of California, Berkeley; the University of Oregon; and the ARAMCO Research and Development Center.
Providing funding were Saudi Aramco, the Murdock Charitable Trust, and the donor-advised fund of Oregon State alumni and retired public school teachers Brian and Marilyn Kleiner through the OSU Foundation.
