Facile Preparation of Hydrophobic Colloidal MFI and CHA Crystals and Oriented Ultrathin Films

Abstract

We report novel routes for synthesis of defect-free, hydrophobic and monodispersed 10 nm (5 unit cells) thick MFI crystals and 100 nm CHA crystals. The crystals are obtained in high yield and display very high 1-butanol adsorption from aqueous solution. These crystals are assembled in monolayers for the growth of ultrathin and uniformly oriented films with thicknesses of 36 nm and 330 nm, respectively, using a synthesis gel in the form of a powder. This method is very simple and may open up for industrial preparation of materials with improved performances.

A novel method for fabrication of high-flux zeolite membranes on supports with arbitrary geometry

“…Si-CHA nanocrystals with a size ranging from 70 to 200 nm were employed as seeds. 37 The masking procedure was identical to the procedure for preparation of MFI membranes. A uniform and dense monolayer of Si-CHA seeds is illustrated in Fig.…”

Gelless Secondary Growth of Zeolitic Aluminophosphate Membranes on Porous Supports with High Performance in CO2/CH4 Separation

“…The membrane orientation with all channels perpendicular to the substrate from the top to the bottom and a thin molecular sieve layer are significant factors affecting the membrane permeance, whereas the membrane selectivity is governed by the continuity of the membrane . Most zeolite membrane preparation methods have focused on the gel composition, the size of seed particles, and the use of co‐templates …”

“…[1-3, 5, 6] Most zeolite membrane preparationmethods have focused on the gel composition, the size of seed particles, and the use of co-templates. [1][2][3][4][5][6][7][8][9][10] Recently,g elless growth methods have been developed and shown promisingr esults for membrane synthesis and performance. [3,5,6] Among commonp rocedures that have been applied to the synthesis of zeolite membranes, gelless secondary growth has great advantages, such as ar equirement for smaller amounts of chemicals, no waste generation,l ow pressure and safe reaction procedures, and elimination of washing and dryings teps for the membrane production.…”

Calcination-Free Fabrication of Highly b-Oriented Silicalite-1 Zeolite Films by Secondary Growth in the Absence of Organic Structure-Directing Agents

“…The synthesis of b -oriented silicalite-1 (S-1) zeolite films, as a typical type of b -oriented MFI film, has particularly been studied to explore its high hydrophobicity. − The first b -oriented S-1 zeolite film was synthesized by in situ crystallization under hydrothermal conditions . In that case, a small amount of a -oriented S-1 zeolite film was always observed.…”

“…In that case, a small amount of a -oriented S-1 zeolite film was always observed. By taking advantage of b -oriented seeds deposited on the substrate, a highly b -oriented S-1 zeolite film could be successfully fabricated, which was named as the secondary growth method. − However, it is still a challenge to prevent the formation of undesired twin crystals on the highly b -oriented S-1 zeolite film.…”