High-Performance Co-Based ZIF-67 Tubular Membrane Achieved by ZnO-Induced Synthesis for Highly Efficient Pervaporation Separation of Methanol/Methyl tert-Butyl Ether Mixture

Abstract

A high-performance and stable Co-based ZIF-67 membrane was successfully fabricated on a tubular substrate by ZnO-induced heteroepitaxial growth for the pervaporation separation of methanol (MeOH)/methyl tert-butyl ether (MTBE) mixture for the first time. Both the strong hydrophilicity and suitable pore size of the prepared ZIF-67 membrane allow methanol to be preferentially adsorbed and separated out from the MeOH/MTBE mixture. For the separation of 15 wt % MeOH/MTBE mixture, close to an azeotrope, the membrane exhibits a separation factor of as high as 3183 and high flux of 1.84 kg·m–2·h–1 at 40 °C, which is superior to almost all the reported membranes for the pervaporation separation of MeOH/MTBE mixture. More importantly, the ZIF-67 membrane with ZnO-linked special microstructure achieved by the heteroepitaxial growth could demonstrate excellent stability with the constant separation performance during the consecutive running over 70 h. Therefore, the high separation selectivity combined with its high stability makes the ZIF-67 membrane a promising candidate for the pervaporation separation of MeOH/MTBE mixture.

Inorganic Pillar Center-Facilitated Counterdiffusion Synthesis for Highly H2 Perm-Selective KAUST-7 Membranes

“…Metal–organic frameworks (MOFs) consisting of organic ligands and metal ions or clusters are a new type of organic–inorganic hybrid porous material with a periodic network structure. In the past two decades, MOFs have attracted enormous attention in the applications of catalysis, adsorption, gas storage, sensors, medical imaging, and electro-optical devices and charge storage. , MOF separation membranes are intensively investigated for separating gas and liquid molecular mixtures, including H 2 separation, − CO 2 capture, − C 3 H 6 /C 3 H 8 , − and separation of organics. − …”

Zeolitic Imidazolate Framework Membranes with a High H2 Permeance Fabricated on a Macroporous Support with Novel Spherical Porous Hybrid Materials

“…11 Instead of Zn 2+ , when Co 2+ is used to coordinate with HmIM, ZIF-67 can be obtained, which also has a SOD topology structure. 12,13 However, the preparation of ZIF-67 membranes is much more difficult than that of ZIF-8 membranes because the homogeneous nucleation rate of the ZIF-67 membrane is too fast. 14 Both ZIF-8 and ZIF-67 membranes can be fabricated through the seeded growth method 15 or the in situ method.…”

“…However, the H 2 /CO 2 separation of ZIF-8 membranes has not shown desirable performance because the lattice flexibility of ZIF-8 enlarges the aperture size to approximately 0.40 nm . Instead of Zn 2+ , when Co 2+ is used to coordinate with HmIM, ZIF-67 can be obtained, which also has a SOD topology structure. , However, the preparation of ZIF-67 membranes is much more difficult than that of ZIF-8 membranes because the homogeneous nucleation rate of the ZIF-67 membrane is too fast …”

Sustainable Fabrication of the Zeolitic Imidazolate Framework-67 Membrane via Supercritical Fluid Processing of the Co-Based Gel Layer

“…ZIF-67, which possesses the formula Co­(Hmim) 2 with SOD topology, has the same theoretical pore aperture as ZIF-8 (∼0.34 nm) . Nevertheless, compared with the ZIF-8 membrane, relevant studies on high-performance ZIF-67 membrane preparation remain quite limited, partially owing to the excessively high nucleation density and growth rate of ZIF-67 crystals in the bulk solution. ,− Surface modification of porous substrates with Co-based buffer layers, which were assumed to serve as both Co 2+ ion sources and ZIF-67 nucleation sites, represents an effective method to solve the problems mentioned above ,− A series of Co-based inorganic compounds have been prepared and demonstrated to be competent buffer layers. For instance, Zhang et al.…”