Abby L. Harvey
GHG Monitor
11/20/2015
Researchers at Queen’s University Belfast have developed a porous liquid that, displaying the benefits of both a porous solid and a liquid solvent, could find future use in carbon capture systems. The material was developed by dissolving rigid organic cage molecules at a high concentration in a solvent too large to enter the pores, creating empty pores in which gases could be trapped. “Our results provide the basis for development of a new class of functional porous materials for chemical processes,” the researchers wrote in a recent article published in the journal Nature.
The new material signals an attempt to increase the efficiency of gas storage. “Porous solids such as zeolites and metal–organic frameworks are useful in molecular separation and in catalysis, but their solid nature can impose limitations. For example, liquid solvents, rather than porous solids, are the most mature technology for post-combustion capture of carbon dioxide because liquid circulation systems are more easily retrofitted to existing plants. Solid porous adsorbents offer major benefits, such as lower energy penalties in adsorption–desorption cycles, but they are difficult to implement in conventional flow processes. Materials that combine the properties of fluidity and permanent porosity could therefore offer technological advantages,” the article explains.
The researchers have developed their porous liquid initially to capture methane, as the gas presents a more difficult challenge that carbon dioxide, which can be captured by more traditional means, according to the article. “Acidic gases, such as carbon dioxide, are absorbed readily by conventional, non-porous solvents such as water or aqueous amines. We therefore focused our initial studies on methane, the main component of natural gas. Methane, like other important gases such as hydrogen, lacks the Lewis acidity of carbon dioxide and hence cannot be absorbed using liquid amines,” the article says. After more testing, the material could potentially be adjusted for carbon capture, the researchers wrote.
“A few more years’ research will be needed, but if we can find applications for these porous liquids they could result in new or improved chemical processes. At the very least, we have managed to demonstrate a very new principle – that by creating holes in liquids we can dramatically increase the amount of gas they can dissolve. These remarkable properties suggest interesting applications in the long terms,” Professor Stuart James, one of the researchers, said in a Queen’s University Belfast press release.
