Researchers at the University Of Oregon Science University have demonstrated the ability of inexpensive (low-cost) nanomaterials to remove carbon dioxide from industrial air. The findings, published in Cell Reports Physical Science, are important because improving carbon sequestration is a key driver of climate change, said OSU‘s Kyriakos Stylianou, who led the study. Carbon dioxide, a greenhouse gas, comes from the burning of fossil fuels and is one of the main causes of global warming.
Companies that monitor carbon from the atmosphere are starting to appear around the world – the largest in the world opened in 2021 in Iceland – but they are not ready to make a big impact on the global climate problem, Stylianou said. In one year, Icelandic plants can produce the amount of carbon dioxide equivalent to the annual production of about 800 cars.
However, the technology for reducing carbon dioxide in the atmosphere, such as factories, is still well developed. One such technology includes nanomaterials called organometallic frameworks, or MOFs, which can block carbon dioxide molecules from spreading as flue gas comes out of the chimney.
Stylianou, assistant professor of chemistry, said, “Carbon dioxide capture is essential to achieve the zero-emissions goal. “MOFs have shown great promise for carbon capture because of their porosity and structural versatility, but synthesizing them often means using both economically and environmentally expensive reagents, such as heavy metal salts and solvents. Toxic.”
Also, treating the liquid portion of the atmosphere makes removing carbon dioxide more difficult, he said. Many MOFs that demonstrated carbon capture ability lost their performance under wet conditions. Flue gas can be dried, Stylianou said, but that adds significant costs to the carbon dioxide removal process, enough to make it impractical for industrial applications.
“Therefore, we want to propose a MOF to address the various limitations of the current materials used in carbon capture: high cost, low selectivity for carbon dioxide, low stability in humid conditions, and air capacity CO2 is low”, he said. MOFs are crystalline, porous materials composed of positively charged metal ions surrounded by organic “binding” molecules called ligands.
The metal ions form a chain that connects the arms of the contacts to create a repeating pattern that resembles a hole; The structure has nanometric pores that absorb gas like a sponge. MOFs can be created with different materials, which determine the properties of MOFs, and there are millions of MOFs that can be made, Stylianou said. Nearly 100,000 of them have been developed by chemical researchers, and the properties of another half million have been predicted.
“In this study, we introduce a MOF composed of aluminum and a fast ligand, benzene-1,2,4,5-tetracarboxylic acid,” said Stylianou. “The reaction of MOF to water takes only a few hours. The MOF has pores of the size and size of CO2 molecules, which means that there are holes for carbon dioxide to enter.
MOF works best in humid conditions and prefers carbon dioxide and nitrogen, which is important because nitrogen oxides are what causes flue gas. Without this option, MOFs can bind to the wrong molecules.
“This MOF is an obvious candidate for water post-combustion carbon capture applications,” Stylianou said. “It is cost effective with exceptional separation performance and can be regenerated and used at least three times with similar absorption capacity.”
Source: Oregon State University
