Georgia Tech researchers have developed hybrid zeolitic imidazolate framework (ZIF) materials that allow for the continuous tuning of their porosity and functionality. ZIF materials in general contain metal centers connected by imidazole linkers. The continuous control over pore characteristics (like size, shape, flexibility, and functional groups) of the hybrid ZIFs means that the materials can be tailored to a specific application, like for CO2/N2 or CO2/CH4 separations for natural gas purification. Leveraging the inherently advantageous properties of ZIF—thermal and chemical stability, high microporosity, and high surface area—researchers have prepared this new model of material to include more than one type of imidazole ligand simultaneously in a tunable manner, a differentiating feature from earlier ZIF models. A unique method of synthesis produces hybrid materials with properties distinctly different from the parent single-linker materials. This synthesis technique provides a platform for tuning functionality or porosity based on the ligands used.
- Tunable: Provides a mechanism for adjusting the porosity and functionality of ZIF materials to be used in a range of applications
- Advanced: Demonstrates significantly higher levels of separation selectivity from molecular mixtures of interest than previous ZIF models
- Scalable: Holds potential for large-scale CO2 separation in different materials, such as membranes and adsorbents
- Natural gas purification
- CO2 capture
- Chemical sensors
Zeolitic imidazolate frameworks are a class of nanoporous metal-organic materials with pore sizes in the range of 0.2 to 0.5 nanometers. Framework modification of porous materials like ZIFs can significantly enhance the performance of these materials by making their properties tunable. This enhancement makes the material significantly more useful for processes like separation, catalysis, and chemical sensors. Importantly, improving material performance also reduces the energy needed for these processes. ZIFs are a good candidate for framework modification because they have been shown to exhibit effects such as “gate-opening” and pore flexibility, meaning they make structural changes during adsorption to allow more (or larger) adsorbate molecules into the framework.