Synthesis of nanostructure hydroxy sodalite composite membranes via hydrothermal method: support surface modification and synthesis method effects

Abstract

Multilayer hydroxy sodalite zeolite membranes were synthesized on the outer surface of support with and without modification via in situ and secondary growth hydrothermal synthesis methods. The synthesized zeolite membranes were characterized by X-ray diffraction, scanning electron microscopy, and single gas (H 2 , N 2 , and n-pentane) permeation measurements at different pressure differences. The membranes synthesized by secondary growth method on the modified support were found to be highly intergrown, but the permeation results for hydrogen and n-pentane at a temperature of 323 K were not repeatable, which can be related to the weak interaction between zeolite layer and substrate. High performance hydroxy sodalite zeolite membrane was successfully formed on a nonmodified α-Al 2 O 3 support by in situ hydrothermal synthesis method. No permeance of n-pentane was measured for this membrane at 323 K and 2 bar so that infinite permselectivity of H 2 /n-C 5 H 12 could be obtained for the four-layer synthesized membrane on the nonmodified support, verifying the synthesis of a good quality hydroxy sodalite zeolite membrane. Figure 10. Scanning electron microscope (SEM) micrographs of surface (left side) and cross-section (right side) of the synthesized sodalite membrane layers on the nonmodified support; (a) monolayer, (b) two-layer by in situ method, (c) two-layer by secondary growth, and (d) three-layer by in situ methods. This figure is available in colour online at www.apjChemEng.com.

Preparation and Evaluation of Nanocomposite Sodalite/α-Al2O3 Tubular Membranes for H2/CO2 Separation

“…Micrographs of SOD crystals collected from the bottom of the autoclave after the hydrothermal synthesis are depicted in Figures 5a and 6b. The SEM images in Figures 5a and 6a show thread-ball shapes of SOD crystals and this observation agree with literature [15,27,28,39,41].…”

“…Zeolite membranes prepared by growing a thin selective zeolite layer referred to as "thin-film" on top of a support via the direct hydrothermal synthesis method [9][10][11][12][13] and via the secondary-seeded growth method [14][15][16][17] are well reported and have produced good membranes. However, when membranes prepared by these techniques are subjected to large temperature changes, Figure 1.…”

Effect of bimetallic NiW modified crystalline ZSM‐5 zeolite on catalytic conversion of crude palm oil and identification of biofuel products

“…These pretreatment steps of kaolin not only assist the formation of the amorphous phase of silica but also enhance the formation of zeolites . Specifically, ZSM‐5 zeolite has been of paramount interest as it has a unique structure, good selectivity and stability, leading to an enhancement in catalytic conversion of vegetable oils via cracking and isomerization of both Lewis and Brönsted‐type acid sites . Acid‐catalyzed transformations of hydrocarbons such as cracking and isomerization are of prime importance.…”

Photocatalytic membrane filtration and its advantages over conventional approaches in the treatment of oily wastewater: A review

“…The addition of tungsten trioxide (WO 3 ) can also enhance the photocatalytic activity of TiO 2 by reducing the recombination rate of e − /h + pairs, and it can result in increased visible light activity 141,180,181 . Some studies show that the deposition of silica, zeolite, clay, or even noble metals such as gold (Au), platinum (Pt), palladium (Pd), copper (Cu), and silver (Ag) nanoparticles onto TiO 2 can both increase the photocatalytic properties and prolong the lifetime of charge carriers; however, the properties of the noble metal should be studied carefully because it can affect the photocatalytic activity 129,139,181–184 . The use of composites containing cadmium sulfide (CdS), silicon dioxide (SiO 2 ), zirconium dioxide (ZrO 2 ), or zinc oxide (ZnO) is also beneficial in terms of the efficiency of organic pollutant decomposition with UV and even with visible light 24,29,183,185 .…”