In the face of increasing CO2 concentrations in the atmosphere and emissions, scientists have been working on solutions to filter the harmful gas out of the air. However, current CO2 absorption methods are not effective in wet gases, which are common in power plants and industrial facilities. Researchers from the Polytechnic University of Lausanne and Oregon State University have identified 35 metal-organic framework compounds with selective CO2 binding that can filter CO2 from wet gases.
Traditional CO2 absorption methods are only effective when the gas is dry. When gases contain large amounts of water vapor, which is the case in most power plants and industrial facilities, the effectiveness of current CO2 absorption methods decreases significantly. This is because both water and CO2 dock at the same binding sites. While drying gases before filtering is technically possible and significantly increases the effectiveness of current CO2 absorption methods, it is rarely done for economic reasons.
To address this issue, researchers used computer simulations to investigate the absorption behavior of more than 300,000 metal-organic framework compounds to find a structure whose binding sites do not simultaneously attract water and CO2. They identified 35 materials with selective CO2 binding that are optimal for filtering wet gases because they have two separate binding sites in their structure – one for water and one for CO2. These materials do not compete with water for the same binding sites as current CO2 absorption methods.
The researchers verified the results of the computer simulation by testing the effectiveness of the metal-organic framework compounds, Al-PyrMOF and Al-PMOF, in the laboratory. The results of the practical test corresponded to the simulation, and both MOFs achieved significantly better results in wet gases than common CO2 absorption methods such as activated carbon or zeolite 13X. The researchers concluded that these materials offer opportunities for more effective and cheaper exhaust gas cleaning. They also explained that the virtual selection process can be used to find absorbers for other gases. A follow-up study will investigate which of the 35 newly identified metal-organic compounds is best suited for industrial use.
Nature: 10.1038/s41586-019-1798-7
