(478d) Hybrid Zeolitic Imidazolate Frameworks for Separation of Small Molecules

Zeolitic Imidazolate Frameworks (ZIFs) are a relatively new class of materials that fall under the broader classification of Metal Organic Frameworks. They have remarkable chemical and thermal stability and their well-defined crystal structures and pore connectivity make them attractive candidates in many separation processes. Recently, hybrid ZIF materials that incorporate two different organic linkers in the same framework have been reported [1]. By varying the composition of the linkers in these materials, it is possible to tune the porosity and functionality of these hybrid materials. In this work, we will demonstrate the use of gravimetric techniques and PFG NMR diffusiometry to study the adsorption and diffusion behavior of small molecules like water and alcohols in hybrid ZIF 8 – ZIF 90 systems. Results have shown that hydrophobicity and diffusivity of small molecules in hybrid ZIFs can be tuned by controlling the composition of linkers. We will also discuss the use of two-dimensional NMR spectroscopy to gain more insight into the structure of hybrid ZIFs. These experimental results will be correlated with the results from numerical computational techniques such as Monte Carlo simulations to study the impact of ordering of linkers on transport properties. We will discuss the potential of using hybrid ZIFs to economically and efficiently separate water and organic molecules from biomass based feedstock.

1.         Thompson, J.A., et al., Hybrid Zeolitic Imidazolate Frameworks: Controlling Framework Porosity and Functionality by Mixed-Linker Synthesis. Chemistry of Materials, 2012. 24: p. 1930-1936.