New material design offers highly efficient carbon capture
Space-filling models of new MOF structure ©Nature
A new mechanism for highly efficient CO2 uptake in carbon-capturing materials has been discovered by an international collaboration including EPFL’s Energy Center. The novel mechanism, published in Nature, offers an energy-efficient route to carbon capture.
Metal-organic frameworks (MOFs) are porous crystal structures made from metal nodes that are connected through organic linkers. MOFs are at the center of carbon-capturing efforts, as they are chemically tunable and can adsorb carbon with high efficiency. A large collaborative study, including EPFL’s Energy Center, has explored the properties of a MOF that shows unusual CO2 adsorption. The study, published in Nature, has found that the new MOF offers potential practical benefits compared to available carbon-capturing technologies.
Carbon-capture and sequestration is a promising method for clearing the build-up of greenhouse gases in the atmosphere. At the moment, implementing carbon capture would raise the cost of electricity from fossil-fuel power plants, mostly because removing CO2 from the effluent stream is too expensive. Consequently, there is an urgent need to find more cost-effective and efficient gas separation technologies, such as MOFs.
In a study led by the University of California Berkeley, in which EPFL’s Energy Center has been involved, scientists have found that inserting CO2 in a metal-amine bond of MOFs can trigger a highly efficient chain reaction of CO2 uptake. The researchers took advantage of the chemical versatility of MOFs, and were able to optimize the conditions of the chain reaction by altering the metal atoms at the nodes of the MOF’s structure.
As a result of this, the MOFs can achieve large capacities in separating CO2 from the atmosphere with only small temperature changes. Meanwhile, the energy required to regenerate MOFs following release of captured CO2 was lower than even state-of-the-art liquid amine solutions. The two most promising MOFs were based on magnesium and manganese, and were able to operate at high temperatures.
The results provide a template for designing highly efficient adsorbent materials that can remove CO2 from various gas mixtures. Compared to available technologies, this design offers advantages in terms of reduced sorbent regeneration energy and reduced materials and system costs.
The authors, who include EPFL Energy Center Director Berend Smit, also suggest that their designs offer striking structural similarities between the magnesium-based MOF and the CO2-fixing photosynthetic enzyme, Rubisco. Therefore, these MOF designs could also bear upon the future of biological CO2 fixation.
This study represents a collaboration of the University of California Berkeley with Zhejiang University, the University of Turin, University of Minnesota, Lawrence Berkeley National Laboratory, Université Grenoble Alpes, the Norwegian University of Science and Technology, Kavli Energy Nanosciences Institute (Berkeley), and EPFL’s Energy Center.
Reference
McDonald TM, Mason JA, Kong X, Bloch ED, Gygi D, Dani A, Crocellà V, Giordanino F, Odoh SO, Drisdell WS, Vlaisavljevich B, Dzubak AL, Poloni R, Schnell SK, Planas N, Lee K, Pascal T, Wan LF, Prendergast D, Neaton JB, Smit B, Kortright JB, Gagliardi L, Bordiga S, Reimer JA, Long JR. Cooperative insertion of CO2 in diamine-appended metal-organic frameworks.Nature, 11 March 2015. DOI: 10.1038/nature14327
