So, I have learned that Metal Organic Frameworks (MOF(s)), a chemical structure with high surface area/mass, are not, on average, appropriate for dilute CO2 capture as sorbents. With that said, there have been success with a couple, and there are hundreds of thousands to millions that have been made, so they are using machine learning to evaluate the best candidates for Direct Air Capture (DAC). Hopefully they find a few more. The surface area can be 10,000 meters squared/gram of sorbent because of the elaborate structure porosity and shape.
As for solvents of Direct Air Capture processes, they suffer from low efficiency. They only meet 50% thermodynamic efficiency. Co mixture, like MEA with DMEA, for example, have the greatest potential so far. Interestingly, they have had solvents that seem to violate chemical engineering principles--The diffusivities increased with increases viscosity. This is quite odd behavior. Still, most of these solvents have high vapor pressures and will evaporate quickly at the operating temperatures. Research continues.
It is well known that solvents can capture more CO2 than sorbents per mass basis. But sorbents require less energy for regeneration.
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References:
[1] Reiner, D., Bui, M., & Mac Dowell, N. (2019). Carbon Capture and Storage. The Royal Society of Chemistry.
Fascinating insights on the challenges and potential of both MOFs and solvents in DAC technology! It's intriguing how machine learning is being used to evaluate MOFs for Direct Air Capture (DAC). This approach could significantly streamline the search for effective CO2 sorbents, highlighting the growing intersection between AI and material science. Your observation about the unusual behavior of solvents, where diffusivity increases with viscosity, suggests unexplored areas in fluid dynamics that could revolutionize solvent-based CO2 capture. Integrating renewable energy sources for the regeneration of sorbents could also enhance the sustainability of these processes. Perhaps exploring hybrid systems that leverage both the efficiency of solvents and the lower energy demands of sorbents could lead to more viable solutions for DAC. Cross-disciplinary collaboration will be crucial in advancing these technologies.