Water-Repelling MOF Turns Humid Flue Gas Into an Advantage for Carbon Capture

Chemists at Oregon State University have unveiled a new carbon capture material that does something most of its predecessors could not: it keeps working in the presence of water. The material, a metal-organic framework nicknamed BVR-X, has been described in the journal Angewandte Chemie, and the university’s scientists, together with collaborators, have filed a patent application covering its synthesis and carbon dioxide capture properties. The breakthrough addresses one of the most stubborn obstacles in industrial emissions control, namely the fact that the steam and moisture swirling through factory smokestacks tend to cripple the very materials designed to strip carbon dioxide out of those gases.

The scale of the problem the material targets is considerable. Industrial activity, including the burning of fossil fuels for energy, accounts for a substantial share of the carbon dioxide accumulating in Earth’s atmosphere. In the United States alone, the Environmental Protection Agency estimates that roughly 30 percent of total greenhouse gas emissions come from industry. Capturing carbon dioxide at the point where it enters the atmosphere, before it can disperse and contribute to global warming, is widely regarded as one of the more practical avenues for mitigating climate change, because point-source technologies are comparatively mature compared with the still-nascent field of direct air capture.

Metal-organic frameworks, or MOFs, are the class of materials at the heart of the new study. They are crystalline solids built from positively charged metal ions surrounded by organic linker molecules known as ligands. The metal ions act as nodes that bind the arms of the linkers, assembling a repeating, cage-like architecture riddled with nanosized pores. Those pores behave something like a molecular sponge, adsorbing gas molecules onto their interior surfaces. Because chemists can swap out the metal nodes and the organic linkers almost at will, the design space is enormous: researchers have already synthesized more than 100,000 distinct MOFs, and the properties of hundreds of thousands more have been predicted computationally.

That structural versatility is precisely why MOFs have long been considered promising candidates for carbon capture. Kyriakos Stylianou, professor of chemistry in the Oregon State University College of Science and director of the university’s Materials Discovery Laboratory, known as the MaD Lab, has emphasized that capturing carbon dioxide is critical for meeting net-zero emission targets and that MOFs have shown considerable promise thanks to their porosity and adaptability. Yet the same porous interiors that make MOFs effective adsorbents also make them vulnerable. In many promising materials, water molecules compete with carbon dioxide for the same adsorption sites, and in humid conditions the water wins, effectively shutting down the capture process.

BVR-X sidesteps this failure mode through an unusual internal organization. Rather than allowing water and carbon dioxide to compete for the same space, the material directs the two molecules to different regions inside its pores, a strategy the researchers describe as pore compartmentalization. Water is shepherded away from the sites where carbon dioxide is captured, so moisture no longer blocks the adsorption chemistry. As Stylianou explained, this internal organization helps the material work under conditions that more closely resemble real industrial emissions, where humidity is not an inconvenience to be engineered away but a constant feature of the gas stream.

The implications of that design choice are economic as much as scientific. Flue gases can, in principle, be dried before they reach a capture bed, but dehumidifying enormous volumes of exhaust adds significant expense, enough to render the carbon dioxide removal process nonviable for many industrial applications. A material that tolerates or even exploits humidity removes that cost barrier entirely. Stylianou noted that water usually makes capturing carbon dioxide more difficult, but that the new material responds to water by changing in a way that lets it keep capturing the greenhouse gas effectively even under very humid conditions, an adaptive behavior that sets it apart from conventional adsorbents.

Laboratory testing put that claim to the test under deliberately challenging conditions. The MOF efficiently captured carbon dioxide from a highly humid stream containing just 4 percent carbon dioxide, a composition relevant to emissions from natural gas combustion. Separating a small amount of carbon dioxide in the presence of substantial water is particularly challenging, Stylianou observed, which makes the result especially relevant for gas-fired power plants and similar facilities. A dilute, wet gas stream is close to a worst-case scenario for many adsorbents, and demonstrating strong performance there suggests the material is built for the messiness of real smokestacks rather than the tidy conditions of a laboratory bench.

Durability and reusability, the qualities that determine whether a laboratory curiosity can become an industrial workhorse, also feature prominently in the findings. According to the researchers, the material can be regenerated and reused, maintaining its performance through dozens of capture-and-release cycles while tolerating demanding conditions. Regeneration, the step in which captured carbon dioxide is released so the adsorbent can be used again, is central to the economics of any capture technology, since a sorbent that degrades after a handful of cycles would need constant replacement. Sustained performance across repeated cycles, combined with tolerance for the heat and chemical variability of flue gas, are important qualities for practical carbon capture technologies.

The study was a collaborative effort. Working alongside Stylianou were MaD Lab members Ankit Yadav, Emmanuel Musa and Andrzej Gładysiak, along with Micah Hickethier, Chun-Wai Chang and Kai Shen Choong of the Oregon State College of Engineering. Scientists from the University of California, Berkeley, the University of Oregon and the ARAMCO Research and Development Center also contributed. Funding came from 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. Saudi Aramco applied for a patent on the synthesis and carbon dioxide capture properties of BVR-X, with several of the researchers listed as co-inventors.

The advance arrives at a moment when the world’s carbon removal infrastructure remains soberingly small. Facilities that filter carbon directly from ambient air are beginning to appear around the globe, including the world’s largest such plant, which opened in Iceland in 2024, but as Stylianou notes they are not yet capable of making a large dent in worldwide emissions; in a year, that Icelandic plant can draw out carbon dioxide in quantities comparable to the annual emissions of roughly 7,200 cars. Point-source capture at factories and power plants, where carbon dioxide is far more concentrated, offers a nearer-term path, and materials like BVR-X, which thrive in the humid, dilute conditions of real exhaust streams, could help close the gap between laboratory promise and industrial deployment in the race toward net-zero emissions.

Subject of Research: A water-tolerant metal-organic framework for industrial carbon capture

Article Title: New material developed at Oregon State provides boost to carbon capture technologies

Article References: New material developed at Oregon State provides boost to carbon capture technologies. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: carbon capture, metal-organic frameworks, MOFs, flue gas, carbon dioxide, greenhouse gas emissions, Oregon State University, adsorption, climate change mitigation, porous materials, net-zero emissions, industrial emissions