A number of aspects of the pre-nucleation zeolite synthesis solution are considered. Various environmental and structural effects on the Si NMR chemical shift of silicon nuclei are investigated, in order to ascertain the necessary computational model for a systematic study of oligomeric silicate species identified or postulated to be present during this phase of zeolite crystal growth. It is de...

In applying a multi-scale spectroscopic and computational approach, we demonstrate that the synthesis of stacked zeolite silicalite-1 nanosheets, in the presence of a long-tail diquaternary ammonium salt surfactant, proceeds through a pre-organised phase in the condensed state. In situ small-angle X-ray scattering, coupled to paracrystalline theory, and backed by electron microscopy, shows that...

Benzene alkylation with propylene was studied in the gas phase using a catalytic membrane reactor and a fixed-bed reactor in the temperature range of 200-300 °C and with a weight hourly space velocity (WHSV) of 51 h-1. β-zeolite was prepared by hydrothermal synthesis using silica, aluminum metal and TEAOH as precursors. The membrane's XRD patterns showed good crystallinity for the β-zeolite fil...

The first zeolite structure (ITQ-40) that contains double four (D4) and double three (D3) member ring secondary building units has been synthesized by introducing Ge and NH(4)F and working in concentrated synthesis gels. It is the first time that D3-Rs have been observed in a zeolite structure. As was previously analyzed [Brunner GO, Meier, WM (1989) Nature 337:146-147], such a structure has a ...

Zeolites with extra-large pores have attracted great attention because of their important applications such as in hydrocracking, catalysis, and separation of large molecules. Despite much progress has been made during the past decades, the synthesis of these materials remains a big challenge. A new extra-large-pore zeolite NUD-1 (Nanjing University Du's group zeolite no. 1) is synthesized by us...

Zeolite membranes are widely used in separation, catalysis, sensors and other fields because of their good diffusion performance, shape selection catalysis capabilities. However, the slow synthesis rate zeolite restricts industrialization process, random orientation seriously affects performance. Therefore, this paper investigates methods for accelerating zeolites roles different was explored. ...

The silicate oligomerization reaction is key to sol-gel chemistry and zeolite synthesis. Numerous experimental and theoretical studies have been devoted to investigating the physical chemistry of silicate oligomers in the prenucleation stage of siliceous zeolite formation. Most of the previous quantum chemical computational work has used gas phase models or continuous solvent models for silica ...

Lactic acid is an important platform molecule in the synthesis of a wide range of chemicals. However, in aqueous solutions without alkali, its efficient preparation via the direct catalysis of sugars is hindered by a side dehydration reaction to 5-hydroxymethylfurfural due to Brønsted acid, which originates from organic acids. Herein, we report that a previously unappreciated combination of com...

Zeolites are nanoporous crystalline alumino-silicates with a rich variety of interesting properties and industrial applications. With over 140 zeolite framework topologies synthetically available—each with its own range of compositions—zeolites offer size-, shapeand electrostaticallyselective adsorption, diffusion and reaction up to remarkably high temperatures. Zeolites are widely used as petr...

The use and application of synthetic zeolites for ion exchange, adsorption and catalysis has shown enormous potential in industry. In this study, X-ray fluorescence (XRF) analysis was used to determine Si and Al in fly ash (FA) precipitates. The Si and Al contents of the fly ash precipitates were used as indices for the alkaline hydrothermal conversion of the fly ash compounds into zeolites. Pr...