Formulation of Metal-Organic Framework Inks for the 3D Printing of Robust Microporous Solids toward High-Pressure Gas Storage and Separation

ACS Appl Mater Interfaces. 2020 Mar 4;12(9):10983-10992. doi: 10.1021/acsami.9b22257. Epub 2020 Feb 21.

Abstract

The shaping of metal-organic frameworks (MOFs) has become increasingly studied over the past few years, because it represents a major bottleneck toward their further applications at a larger scale. MOF-based macroscale solids should present performances similar to those of their powder counterparts, along with adequate mechanical resistance. Three-dimensional printing is a promising technology as it allows the fast prototyping of materials at the macroscale level; however, the large amounts of added binders have a detrimental effect on the porous properties of the solids. Herein, a 3D printer was modified to prepare a variety of MOF-based solids with controlled morphologies from shear-thinning inks containing 2-hydroxyethyl cellulose. Four benchmark MOFs were tested for this purpose: HKUST-1, CPL-1, ZIF-8, and UiO-66-NH2. All solids are mechanically stable with up to 0.6 MPa of uniaxial compression and highly porous with BET specific surface areas lowered by 0 to -25%. Furthermore, these solids were applied to high-pressure hydrocarbon sorption (CH4, C2H4, and C2H6), for which they presented a consequent methane gravimetric uptake (UiO-66-NH2, ZIF-8, and HKUST-1) and a highly preferential adsorption of ethylene over ethane (CPL-1).

Keywords: 3D printing; ethane/ethylene separation; ink formulation; metal−organic frameworks; methane storage.