Ethanol perm‐selective B‐ZSM‐5 zeolite membranes from dilute solutions

Abstract

in Wiley Online Library (wileyonlinelibrary.com) Boron-substituted MFI (B-ZSM-5) zeolite membranes with high pervaporation (PV) performance were prepared onto seeded inexpensive macroporous a-Al 2 O 3 supports from dilute solution and explored for the separation of ethanol/water mixtures by PV. The effects of several parameters on microstructures and PV performance of the B-ZSM-5 membranes were examined systematically, including the seed size, synthesis temperature, crystallization time, B/Si ratio, H 2 O/SiO 2 ratio and silica source. A continuous and compact B-ZSM-5 membrane was fabricated from solution containing 1 tetraethyl orthosilicate/0.2 tetrapropylammonium hydroxide/0.06 boric acid/600 H 2 O at 448 K for 24 h, showing a separation factor of 55 and a flux of 2.6 kg/m 2 h along with high reproducibility for a 5 wt % ethanol/water mixture at 333 K. It was demonstrated that the incorporation of boron into mobile five (MFI) structure could increase the hydrophobicity of B-ZSM-5 membrane evidenced by the improved contact angle and amount of the adsorbed ethanol, and thus enhance the PV property for ethanol/water mixtures.

Effects of Silica-Particle Coating on a Silica Support for the Fabrication of High-Performance Silicalite-1 Membranes by Gel-Free Steam-Assisted Conversion

“…The PV performances of the membranes fabricated in the present study were also compared with those of silicalite-1 membranes prepared on tubular supports by HT [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21] and on silica supports by the gel-free SAC method [22] in previous studies (Figure 5). The silicalite-1 membranes fabricated in this study on the silica-particle-coated supports using the gel-free SAC method showed very high PV performances as well as highest membrane selectivity (α mem ) compared with the previously reported membranes [28].…”

“…Silicalite-1 membranes are generally prepared by hydrothermal synthesis (HT) using an in-situ crystallization or secondary growth method [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. In both cases, the synthetic gel is prepared by mixing a silica source, a structure-directing agent (SDA), a mineralizing agent, and water and immersing the support in this mixture to synthesize the membrane.…”

An Organoselective Zirconium‐Based Metal–Organic‐Framework UiO‐66 Membrane for Pervaporation

“…From the single pervaporation tests of alkylbenzenes, the flux of p-and m-xylene were 0.58 and 0.26 kg m -2 h -1 , respectively, and that of 0.07 kg m -2 h -1 for 1,3,5-trimethylbenzene was much lower than those for xylenes. This could be explained by the molecular sieving effect (the molecular sizes of p-, mxylene, and 1,3,5-trimethylbenzene are 0.67, 0.71, and 0.76 nm, [5] EtOH/water ZIF-71 5 298 2.60 6.88 [27] EtOH/water silicalite-1 10 333 1.4 85 [28] EtOH/water B-ZSM-5 10 333 2.6 55 [29] EtOH/water ZIF-8/PDMS [a] 5 333 1.23 9.9 [30] EtOH/water MIL-53/PDMS [a] 5 353 5.47 11.1 [31] EtOH/water silicalite-1/PDMS [a] 5 323 5.52 15.5 [32] MeOH respectively). Thus, on the basis of its pore size, these results indicate that the membrane had a few defects larger than the pore size.…”

Membranes for bioethanol production by pervaporation

“…Saboor et al reported that B-ZSM-5 membranes fabricated from clear synthesis solutions (H 2 O/SiO 2 = 64) on seeded α -alumina discs preferentially permeated ethanol from water, showing a relatively high permeation flux of 1110 g·m −2 ·h −1 but a low separation factor of 13.9. Recently, Chai and co-workers observed a high permeation flux of 2600 g·m −2 ·h −1 and a moderate separation factor of 55 using a B-ZSM-5 membrane synthesized from a dilute solution (H 2 O/SiO 2 = 600) on seeded inexpensive macroporous α -alumina tube [ 217 ]. It suggests that the PV performance for B-ZSM-5 membranes is greatly dependent on their preparation conditions.…”