Porous liquids, which combine permanent porosity and fluidity, can have advantages over porous solids in some applications. For example, porous liquids can be used in continuous-flow processing for post-combustion CO2 capture. They have previously been used for the sequestration and separation of different types of gases, but methods that allow the conversion of the adsorbed gases into useful chemicals are still rare.
Kamendra P. Sharma, Indian Institute of Technology Bombay, Mumbai, and colleagues have developed a multifunctional porous liquid (pictured) based on hollow silica nanorods and a carbonic anhydrase enzyme. The hollow silica nanorods were fabricated using a micelle template method and functionalized with an organosilane (pictured in pink) and a polymer surfactant (pictured in blue) to obtain a porous liquid. Then, acidic residues of the carbonic anhydrase were converted to amides, and the enzyme was modified using a PEG-based polymer surfactant and freeze-dried. The two components were dispersed in a phosphate buffer at a nanorod-to-enzyme ratio of 1:50, and the mixture was freeze-dried to obtain the desired solvent-free porous liquid composite (PoLi-bCA).
This porous liquid not only reversibly sequesters and stores CO2 but also catalytically converts it to calcium carbonate. The hollow silica nanorods sequester and store the CO2 molecules, while the carbonic anhydrase enzyme acts as a catalyst for the conversion of CO2 to CaCO3 upon the addition of CaCl2. The liquid-like property of the material, with a room-temperature viscosity similar to that of honey, is provided by the polymeric shell surrounding the nanoparticles and the enzyme. The work acts as a proof-of-concept for performing chemical reactions within porous liquids to create value-added chemicals from gases.
- Composite Porous Liquid for Recyclable Sequestration, Storage and In‐situ Catalytic Conversion of Carbon Dioxide at Room Temperature,
Kamendra Prakash Sharma, Archita Bhattacharjee, Raj Kumar,