Article by: Andacs Robert Eugen, on 08 July 2023, at 08:57 am PDT

A team of researchers from Oregon State University College of Science has made significant strides in harnessing the potential of an affordable nanomaterial to effectively remove carbon dioxide from industrial emissions.

The study, which was recently published in Cell Reports Physical Science, holds great importance as improved carbon capture methods are crucial in combatting climate change, as stated by Kyriakos Stylianou, the lead researcher from OSU.

Carbon dioxide, a greenhouse gas primarily released through the burning of fossil fuels, is a major contributor to global warming.

While carbon filtering facilities are beginning to emerge worldwide, with the largest one inaugurated in Iceland in 2021, they are not yet capable of making a substantial impact on the global emissions issue. For instance, the Iceland plant can only extract an amount of carbon dioxide equivalent to the annual emissions of approximately 800 cars within a year.

However, technologies focusing on mitigating carbon dioxide emissions at the source, such as industrial factories, have made notable progress. One such technology involves the use of nanomaterials called metal-organic frameworks (MOFs), which can capture carbon dioxide molecules through adsorption as flue gases pass through smokestacks.

"The capture of carbon dioxide is crucial for achieving net-zero emission targets," explained Stylianou, an assistant professor of chemistry. "MOFs have shown significant promise in carbon capture due to their porosity and structural versatility. However, their synthesis often involves costly and environmentally unfriendly reagents, such as heavy metal salts and toxic solvents."

Furthermore, dealing with the presence of water in smokestack gases presents a significant challenge in carbon dioxide removal. Many MOFs that exhibit potential for carbon capture lose their effectiveness in humid conditions. While flue gases can be dried, this significantly adds to the cost of the carbon dioxide removal process, rendering it impractical for industrial applications.

Hence, the researchers aimed to develop a MOF that overcomes the limitations of existing carbon capture materials: high cost, poor carbon dioxide selectivity, low stability in humid conditions, and limited CO2 uptake capacities.

MOFs are crystalline, porous materials composed of 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, forming a repeating structure resembling a cage with nanosized pores capable of adsorbing gases, akin to a sponge.

MOFs can be designed using various components that dictate their properties, and there are millions of potential MOFs, with nearly 100,000 already synthesized by chemistry researchers and the properties of another half-million predicted.

"In this study, we introduced a MOF consisting of aluminum and a readily available ligand, benzene-1,2,4,5-tetracarboxylic acid," elaborated Stylianou. "The synthesis of this MOF occurs in water and only takes a few hours. Moreover, the MOF possesses pores that are comparable in size to CO2 molecules, providing a confined space for capturing carbon dioxide."

The MOF exhibits excellent performance in humid conditions and has a preference for carbon dioxide over nitrogen, which is crucial considering that nitrogen oxides are present in flue gases. Without this selectivity, the MOF could potentially bind to the wrong molecules.

"This MOF is an exceptional candidate for wet post-combustion carbon capture applications," emphasized Stylianou. "It is cost-effective, showcases exceptional separation performance, and can be regenerated and reused at least three times while maintaining comparable uptake capacities."

The research involved collaboration with scientists from Columbia University, the Pacific Northwest National Laboratory, and Chemspeed Technologies AG in Switzerland. Additionally, Oregon State chemists Ryan Loughran, Tara Hurley, and Andrzej Gładysiak contributed to the study.