Particle Size Control of Metal-Organic Frameworks by Cryogenic Grinding for Producing Mixed Matrix Membranes

Particle Size Control of Metal-Organic Frameworks by Cryogenic Grinding for Producing Mixed Matrix Membranes

K. Zhang, Y.G. Huang, S. Han, K. Walton, C. Meredith, W.J. Koros, D.S. Sholl

Georgia Institute of Technology

School of Chemical & Biomolecular Engineering

Atlanta, GA

Abstract

Metal organic frameworks (MOFs) have been explored as possible fillers in mixed matrix membranes (MMMs) to improve pure polymeric membrane properties. Appropriate particle size of MOFs is desired in MMMs to achieve satisfactory dispersion and adhesion to the polymer matrix, and to control the thickness of skin layers of hollow fiber. Here, we reported an effective strategy to control the particle size of MOFs through cryogenic grinding using liquid nitrogen bath. The particle size and crystal structure of cryogenic ground MOFs were analyzed and compared with conventional ground MOFs. Adsorption tests on CO₂ and N₂ were carried out utilizing cryogenic ground MOFs. Specially, we have incorporated cryogenic ground MOFs into a polymer matrix to produce composite films. These films were tested over a range of temperatures and a variety of gases. The analysis confirmed the usefulness of cryo-ground process in producing appropriate particle size of MOFs for MMMs. We will also illustrate MOF types where the size reduction was not successful to seek criteria for potentially predicting when cryo-grinding is likely to be successful, and when it may not be used without undermining the intrinsic transport properties of the intrinsic MOF.

Acknowledgement

This project is funded by the ARPA-E IMPACCT Program via award DE-FOA-0000208