For the last 75 years, the best method to reduce the carbon dioxide from the emitted gases was to use processes based on chemical absorption using monoethanolamine (MEA). This is a general-purpose solvent that has evolved very little during years, and it is non-selective, corrosive, and it needs large equipment. Not the least, it is effective only in low or moderate pressure of carbon dioxide.
Coal-fired power plants are very common almost all the globe, and the new method the scientists from Lawrence Livermore National Laboratory developed might help to have a cleaner and more efficient air.
Their method uses ionic liquids – a special type of molten salt that becomes liquid under the boiling point of water (100 degrees Celsius) – and it is a more viable and stable method than the monoethanolamine chemical absorption method.
The new method brings solutions to many of the old method’s problems. Ionic liquids are solvents with almost no vapor pressure, and one of the most important things is that they do not evaporate, not even under high temperature conditions.
Amitesh Maiti’s (Lawrence Livermore National Laboratory scientist) article about the ionic liquid capturing method can be read in the newly edited journal ChemSusChem, a journal covering chemistry and sustainability topics.
Advantages of the new solution:
- high chemical stability;
- low corrosion;
- almost zero vapor pressure;
- supportable on membranes;
- and a huge library of ion choices, which can be potentially optimized for CO2 solubility.
How they found this solution? The first step was to create a computational reliable method to find the best ionic liquid or solvent suitable for absorbing the CO2.
Amitesh Maiti says: “It’s a great advantage to have a method that can quickly and accurately compute CO2 solubility in any solvent, especially under the range of pressures and temperatures as would be found in a coal-fired power plant. With ionic liquids serving as the solvent, the process could be a lot cleaner and more accessible than what is used today.”
Compared with the ionic liquids used in the last years, the one Maiti discovered is twice as efficient. The computational method reduced a lot the time and money involved for discovering the new substances.
“But each new experiment costs time and money and is often hindered because a specific ionic liquid may not be readily available. By creating a computational tool that can decipher ahead of time which ionic liquids work best to separate CO2, it can be a much more efficient process when field tests are conducted”, said Maiti.
The new approach from LLNL using quantum chemistry based thermodynamic to compute efficiency of the new solutions of absorbing CO2 could show the best performing ionic liquid for this issue. The theoretical data was confirmed by comparision with the experimental values accumulated over the last years.
“With the vast choices of ions, we have barely scratched the surface of possibilities,” Maiti said.
Computational method is used in a lot of industrial fields already and from now on, scientists could rely on this method to discover new substances able to absorb even more CO2, leading to a better world for us and our children.