Zeolites are natural and synthetic materials containing siliceous aluminosilicate frameworks with well-defined microporous structures, large specific surface areas (BSAs) and compensated cations.zeolite s-1 They are used in a wide variety of applications such as gas drying, air separation, hydrogen purification, separating paraffin isomers and xylene isomers, capture and storage of methane, light hydrocarbons and gases, carbon dioxide capture and sequestration, and catalytic deoxygenation reactions.zeolite s-1
The pore structure of zeolites is determined by their crystal structure and the size of the Si/Al ratios of the aluminosilicate framework.zeolite s-1 The structural and chemical properties of zeolites determine their potential use as catalysts in different reactions. The performance of zeolite-based catalysts mainly depends on the type of adsorption and diffusion mechanisms in their microporous pores, i.e. the Si/Al ratios and Al distributions of the aluminosilicate network, as well as the presence of defects and silanol groups.
To improve the performance of zeolite-based catalysts, the adsorption and diffusive properties of the zeolite crystals must be tailored by various post-synthesis techniques.zeolite s-1 These include changing the Si/Al ratios of the initial mixture, dissolving the zeolite to change its composition, and introducing extra species to modify the condensation reaction (i.e. ch-OSDA, anatase and fauruse s-1 zeolites).
One of the most important post-synthesis methods is to regulate the Si/Al ratios of zeolite crystals by selectively removing the Si or Al from the aluminosilicate framework.zeolite s-1 This method is referred to as "top-down" regulation. It is a highly efficient way to obtain new zeolite structures with improved performance, but the synthesis of zeolites based on this strategy requires high temperatures and long preparation times.
In recent years, much attention has been paid to the development of efficient synthesis routes for TS-1 zeolite.zeolite s-1 The synthesis of TS-1 zeolite by a solvent-free process is of particular interest because it can lead to the production of large quantities of hierarchical zeolite samples with excellent catalytic performance for deoxygenation reactions, such as epoxidation.
Recently, Du et al.zeolite s-1 reported a novel method for the synthesis of hierarchical TS-1 zeolite using loose dry gels without the addition of mesoporous organic templates, which allows for fast steam diffusion and rapid crystallization. They prepared a highly porous TS-1 zeolite sample with a BET surface area of 392 m2/g and a total pore volume of 0.105 cm3/g. Moreover, the obtained TS-1 zeolite has strong oxygen adsorption and hydrogen uptake capabilities, as indicated by its 29Si NMR spectrum (Figure 1C), which shows a sharp increase in the signal at -113 ppm associated with the 4-coordinative Si species.
Nevertheless, many challenges are faced in the synthesis of TS-1 zeolite with low cost and high efficiency, including its high water consumption, inefficient dehydration, and adsorption of organic ions.zeolite s-1 Therefore, further research on the synthesis of TS-1 zeolite is necessary to overcome these barriers. We hope that the work presented here will provide a useful overview of the current progress in this field, and inspire further research on the synthesis of TS-1 with more economic and sustainable raw materials.
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