Purification and dehydration of ethyl acetate are important processes in chemical production, and the preparation of stable and efficient pervaporation membrane materials has still been a challenge. In this work, a well-intergrown polycrystalline Al-Fum@CS tubular membrane was successfully prepared by a synergistic strategy involving seeded growth combined with surface remediation and applied for the first time in the separation of a multicomponent mixture containing ethyl acetate by pervaporation. By regulating the synthesis conditions, a continuous Al-Fum membrane with thickness of 1.7 μm was initially grown within the innermost part of a uniform seed layer. Subsequently, a chitosan (CS) layer was introduced onto the membrane to fabricate the Al-Fum@CS membrane. This CS layer significantly modifies the defects existing in the membrane surface. The obtained Al-Fum@CS membrane with the thickness of around 1.8 μm is dense and has strong hydrophilicity. It can preferentially separate water from a ternary azeotropic mixture of water–ethanol–ethyl acetate and displays high pervaporation performance with a permeation flux of 1.88 kg/(m2·h) and a separation factor of ∼6000 at 60 °C. Especially, the Al-Fum@CS membrane can be continuously operated for more than 150 h without any obvious change in separation performance, showing excellent ultrahigh stability. Moreover, the as-prepared membrane has good acid resistance and reusability in complex environments according to the results of multiple mixture pervaporation experiments. Therefore, the Al-Fum@CS tubular membrane has great industrial application potential for the purification of ethyl acetate produced from the esterification reaction.
Efficient CH 4 /N 2 separation is necessitated for obtaining purified methane from natural gas. Aluminum-based metal–organic frameworks (Al-MOFs) have potential for industrial separation applications due to their structure-tunable, low-cost, and scalable features. Intrigued by the impressive selectivity of a recently reported Al-MOF (Al-CDC) toward CH 4 over N 2 , we herein further study the potential of Al-MOFs as adsorbent for CH 4 /N 2 separation, mainly considering the effects of pore geometry and linker polarity. Utilization of two bent ligands and two linear ligands with different polarity afforded two one-dimensional square-shaped Al-MOFs i.e., CAU-10-H, MIL-160, and two rhombic-shaped counterparts i.e., Al-Fumarate (Al-Fum), MIL-53(Al)), respectively. Afterward, pure CH 4 and N 2 adsorption experiments were conducted at 273–313 K for assessing the CH 4 /N 2 separation performance. The results indicated that all the Al-MOFs exhibited superior affinity toward CH 4 over N 2 , and the CH 4 uptake followed the sequence of Al-Fum > CAU-10-H > MIL-53(Al) > MIL-160. Exhilaratingly, Al-Fum exhibited unprecedented CH 4 /N 2 selectivity (17.2) and high CH 4 uptake at 273 K and 1.0 bar. The mechanism underlying the disparity of Al-MOFs affinity toward CH 4 was deciphered via theoretical simulation, suggesting that the synergetic effects of accessibility of strong affinity sites (μ 2 -OH) on AlO 6 chains and polar pore surface induced by varying linkers highly promoted the CH 4 uptake. Furthermore, the results of cyclic adsorption–desorption experiments and binary breakthrough tests validated the feasibility of Al-Fum for practical application.
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