Ionic liquids as an alternative to CO2 post-combustion capture

Anthropogenic CO2 emissions come mainly from combustion processes such as the energy production from fossil fuels. Therefore, the control CO2 emissions from these sources by capture and storage should be extremely important to minimize CO2 contribution to climate change without stifling economic and technological development. There are three main approaches to capturing the CO2 produced: precombustion, oxyfuel combustion and postcombustion. Of these, postcombustion treatment is the most suitable option for retrofitting in existing fuel powered plants without major modifications. The current state-of-the-art of post-combustion technologies for CO2 capture are amine based methods, though it is known the hight energy penalty of these processes, so that in the past decade new alternatives has been explored, as ionic liquids (ILs). The ILs can be defined as salts whose melting point is below 100 degrees C. There are about 10(18) possible structures for ionic liquids, which allows by selecting components (anion or cation) adjust their properties to the required application. The ILs have interesting properties such as high thermal stability, wide temperature liquid range, almost null vapor pressure, good solubility of CO2 and tunable properties through an adequate combination of ions (task specific fluids). Recently several studies have used hydrophilic ionic liquids based on organic anions such as acetate and phenolate, which appear to interact chemically with CO2 allowing high CO2 capture at atmospheric pressures. This contribution tries to give an overview about the use of ionic liquids for CO2 capture and major future strategies to optimize their use.