Selective Defect‐Patching of Zeolite Membranes Using Chemical Liquid Deposition at Organic/Aqueous Interfaces

Abstract

The elimination of possible defects is indispensable in making zeolite membranes popular in process industries. A novel counter‐diffusion chemical liquid deposition (CLD) technique is proposed and developed for selective defect‐patching of zeolite membranes. Dodecyltrimethoxysilane (DMS) is employed as the silane coupling agent, forming a protective layer on the membrane surface so that intracrystalline pores can be kept intact in the subsequent reparation step. By using tetraethoxy orthosilicate (TEOS) and (3‐chloropropyl)triethoxysilane (3CP‐TES), co‐hydrolysis and co‐condensation at the organic/aqueous interface fabricate the silsesquioxane/silicate hybrid on macro‐, meso‐ and even microdefects. The silicalite‐1 membrane before and after reparation is characterized using contact‐angle measurements, Fourier transform IR spectroscopy, and electron probe microanalysis. Permporometry is conducted to study the pore‐size distribution of the membrane before and after reparation. It is found that the silsesquioxane/silicate hybrid is only deposited at the pore‐mouth of the defects, and the defects can be plugged to less than 1.3 nm pores after patching. After reparation, the separation factor of a 50/50 n/i‐butane‐gas mixture through the membrane can be increased to 35.8 from 4.4, and the separation factor of a CO2/N2 gas mixture through the membrane can be increased to around 15 from 1, while keeping the two‐thirds CO2 permeation flux of the synthesized membrane.

Synthesis of Silicalite Membrane with an Aluminum-Containing Surface for Controlled Modification of Zeolitic Pore Entries for Enhanced Gas Separation

“…The CCD modification was terminated in 4 h when the online-monitored α O2/N2 and P m,H2 stabilized at 14 and of 1.2 × 10 −7 mol/m 2 ·s·Pa, respectively. The CCD modified membrane was tested for O 2 /N 2 separation and then treated by the CLD method for reducing the intercrystalline pores, which was similar to that reported in literature [27,28]. The CLD modification was conducted by the following procedure.…”

The seeded growth of dense and thin SAPO-34 membranes on porous α-Al2O3 substrates under microwave irradiation

“…Zeolites membranes with well defined pore structure have exhibited excellent performances in membrane separation and/or catalysis, chemical sensors, corrosion-resistant coatings and microelectronic devices [1][2][3][4]. As a type of silicoaluminophosphate microporous zeolite, SAPO-34 with a pore size of 0.38 nm and the chabazite (CHA) topology framework has been successfully employed to separate carbon dioxide or hydrogen from gas mixtures or to catalyze methanol-to-olefin reaction and hydrocarbon transformation [5,6].…”

Synthesis and Characterization of CuO Nanoparticles by the Chemical Liquid Deposition Method and Investigation of its Catalytic Effect on the Thermal Decomposition of Ammonium Perchlorate

“…Among these, the CLD method is a facile and cost effective route for synthesizing NTMOs that utilizes cheap, nontoxic and environmentally benign precursors [29]. The CLD method has promising advantages, such as a relatively low calcination temperature and produces homogenous and pure final materials [30][31][32].…”