New highly porous materials called MOFS, (metal organic framework) are now in commercial use capturing CO2 from waste streams at cement processing plants and other locations.
Engineers are amazing. Fan the embers of hope when we can.
Now, chemists at the University of California, Berkeley, have discovered that a porous material can act like a sponge to capture CO2 at temperatures close to those of many industrial exhaust streams. The material — a type of metal-organic framework, or MOF — will be described in a paper to be published in the Nov. 15 print edition of the journal Science.
The dominant method for capturing carbon from power or industrial plant emissions employs liquid amines to absorb CO2, but the reaction only works efficiently at temperatures between 40 and 60 C (100–140 F). Cement manufacturing and steelmaking plants produce exhaust that exceeds 200 C (400 F), and some industrial exhaust approaches 500 C (930 F). New materials that are now being piloted, including a subclass of MOFs with added amines, break down at temperatures above 150 C (300 F) or work far less efficiently.
“A costly infrastructure is necessary to take these hot gas streams and cool them to the appropriate temperatures for existing carbon capture technologies to work,” said UC Berkeley postdoctoral fellow Kurtis Carsch, one of two co-first authors of the paper. “Our discovery is poised to change how scientists think about carbon capture. We’ve found that a MOF can capture carbon dioxide at unprecedentedly high temperatures — temperatures that are relevant for many CO2 emitting processes. This was something that was previously not considered as possible for a porous material.”
“Our work moves away from the prevalent study of amine-based carbon capture systems and demonstrates a new mechanism for carbon capture in a MOF that enables high temperature operation,” said UC Berkeley graduate student and co-first author Rachel Rohde.
Like all MOFs, the material features a porous, crystalline array of metal ions and organic linkers, with an internal area equivalent to about six football fields per tablespoon — a huge area for adsorbing gases.
“As a result of their unique structures, MOFs have a high density of sites where you can capture and release CO2 under the appropriate conditions,” Carsch said.
Under simulated conditions, the researchers showed that this new type of MOF, known as ZnH-MFU-4l, can capture hot CO2 at concentrations relevant to the exhaust streams of cement and steel manufacturing plants, which average 20% to 30% CO2, as well as less concentrated emissions from natural gas power plants, which contain about 4% CO2.
Hope.