Aqueously Cathodic Deposition of ZIF‐8 Membranes for Superior Propylene/Propane Separation

Abstract

Electrochemical deposition has emerged as a novel approach to fabricate metal–organic framework (MOF) films. Here, for the first time, an aqueously cathodic deposition (ACD) approach is developed to fabricate ZIF‐8 type of MOF membranes without addition of any supporting electrolyte or modulator. The fabrication process uses 100% water as the sole solvent and a low‐defect density membrane is obtained in only 60 min under room temperature without any pre‐synthesis treatment. The membrane exhibits superior performance in C3H6/C3H8 separation with 182 GPU C3H6 permeance and 142 selectivity, making it sit at the upper bound of permeance versus selectivity graph, outperforming majority of the published data up to 2019. Notably, this approach uses an extremely low current density (0.13 mA cm−2) operated under an ultrafacile apparatus set‐up, enabling an attractive way for environmentally friendly, energy efficient, and easily scalable MOF membrane fabrications. This work demonstrates a great potential of aqueously electrochemical deposition of MOF membrane in the future research.

Membrane‐Based Olefin/Paraffin Separations

“…further developed electrochemical deposition using water as the solvent without addition of any electrolyte or modulator. [ 72 ] Vapor deposition is also a simple and controllable process, such as the gel–vapor deposition (GVD) method (Figure 8b). [ 73 ] However, solvent cannot be avoided during the overall GVD process.…”

Recent Progress in a Membrane-Based Technique for Propylene/Propane Separation

“…Metal organic framework (MOF) membranes have received a great deal of attention over the years due to their potential for use in high-efficiency gas and liquid purification [ 15 , 63 , 64 ]. Among the large family of MOF membranes, ZIF membranes, consisting of zinc ions bridged with the imidazolate ligands show great potential for hydrocarbon separations [ 63 , 65 , 66 , 67 , 68 , 69 , 70 ]. In this section, we mainly focus on the development of ZIF-8 and ZIF-67 membranes for the C 3 H 6 /C 3 H 8 separation based on many reported studies.…”

“…The evaluation of single gas permeation measurement clearly indicated that the ideal C 3 H 6 /C 3 H 8 selectivity increased with the IPTES density and approached 36, with a C 3 H 6 permeance of 8.5 × 10 −8 mol m −2 s −1 Pa −1 (254 GPU). Recently, an aqueously cathodic (ACD) deposition strategy was developed for the preparation of ZIF-8 membranes by Wei et al, as shown in Figure 6 c [ 69 ]. No electrolyte, modulator, or organic solvent was added during the synthesis procedure, and thus, this is an eco-friendly and energy-saving approach.…”

Ultrathin Low‐Crystallinity MOF Membranes Fabricated by Interface Layer Polarization Induction

“…X‐ray photoelectron spectroscopy (XPS) characterization (Figure 2; Figure S4, Supporting Information) confirms that the LC‐MOF membranes show lower binding energy compared with MOF particles, resulting from large increases in the amount of open metal sites and decreases in the crystallinity. [ 15 ] This may be attributed to the following factor. During LC‐MOF membrane formation, the organic interface layer was immersed into a pure methanol solution.…”