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

Abstract

Calcination-free fabrication of highly b-oriented silicalite-1 (S-1) zeolite films in the absence of organic structure-directing agents (OSDAs) is attractive but still challenging. Herein, for the first time, we show a novel route for calcination-free synthesis of a b-oriented S-1 zeolite film in the absence of OSDAs. The key to this success is a rational secondary growth of zeolite crystals on the surface of supports by avoidance of the formation of zeolite nuclei in the system due to the absence of OSDAs. Because of OSDA-free synthesis of S-1, it not only reduces the cost of zeolite films but also avoids the calcination of OSDAs in the synthesis, thus avoiding the formation of cracks in the zeolite films. In addition, the calcination-free fabrication is favorable for reduction of zeolite film defects such as a terminal OH group. As a result, the zeolite films obtained from this work exhibit higher hydrophobicity than the conventional one. Furthermore, the current polarization curve of this S-1 zeolite film shows excellent corrosion resistance. The aforementioned features would be potentially important for industrial application of zeolite films in the near future.

ZSM-5 Membranes Fabricated through Template-Free Gel for Energy Storage

“…Preparation of crystalline membranes on support is an alternative method to fully use of the advantages of crystalline materials. − ZSM-5 zeolite is proved to be a potential proton conductive material, where protons can be transported within the window of about 0.55 nm and larger vanadium ions cannot pass through. , In general, expensive organic templates were used for the preparation of zeolite membranes . During the crystallization process, organic templating agents can enter the ZSM-5 zeolite layer leading to pore blockage, which requires a high temperature calcination procedure to remove the organic templating agents to expose the pores. − However, during the calcination to remove the organic templating agent process, the zeolite membrane is prone to cracks and pinholes because of the difference in thermal expansion coefficients between zeolite membranes and supports, resulting in membrane damage, , which limits the further application of zeolite membranes for flow batteries.…”

Silicalite-1/PDMS Hybrid Membranes on Porous PVDF Supports: Preparation, Structure and Pervaporation Separation of Dichlorobenzene Isomers

“…Fortunately, in our previous study, we have successfully adopted dense and continuous silicalite-1/α−Al 2 O 3 membranes for the pervaporation separation of DCB from binary−isomers solutions [3]. Despite the template−free method, fabricated silicalite-1/α−Al 2 O 3 membranes exhibit excellent DCB pervaporation separation properties, the large−scale preparation of the silicalite-1/α−Al 2 O 3 with structural integrity is still a huge technical difficulty [36,37], which seriously hinders its future industrial application in DCB separation field. To our knowledge, the preparation of dense and continuous zeolites-polymer hybrid membranes is simpler and more controllable than inorganic zeolites membranes, which providing a new possible strategy for DCB separation.…”