Revealing scenarios of interzeolite conversion from FAU to AEI through the variation of starting materials

Abstract

Interzeolite conversion, which refers to the synthesis of zeolites using a pre-made zeolite as the starting material, has enabled promising outcomes that could not be easily achieved by the conventional...

Synthesis strategies to control the Al distribution in zeolites: thermodynamic and kinetic aspects

“…125 Wakihara and co-workers reported similar observations in the synthesis of AEI-type zeolites by applying amorphous aluminosilicate precursors. 126 The initial amorphous precursors were prepared by mixing colloidal silica and sodium aluminate under alkaline conditions at room temperature for 24 h. The authors modified the amorphous precursors by dealumination with a 0.4 M H 2 SO 4 solution. The properties of the modified precursors were compared with those of the initial ones using 27 Al MAS NMR and UV Raman spectroscopies and X-ray pair distribution function analysis.…”

Accelerated Crystallization of LTA Zeolite Using a Combination of High-Silica FAU Zeolite with Low Crystallinity and Additional Al Sources

“…Thermogravimetric-differential thermal analysis (TG-DTA) was performed using a differential thermal analyzer (Thermo plus TG8120, RIGAKU) at a heating rate of 10 °C/min up to 800 °C, using a mixture of 20% O 2 and 80% N 2 as the carrier gas at a flow rate of 0.20 L/min. Solid-state 27 Al magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra were recorded using a JNM-ECZ400 (JEOL) NMR spectrometer at 104.17 MHz with a pulse length (π/2) of 3.0 μs, relaxation delay of 1.2 s, and spinning frequency of 14 kHz. The 29 Si MAS NMR spectra were recorded using a π/2 pulse length of 2.4 μs, relaxation delay of 30 s, and spinning frequency of 10 kHz.…”

“…As shown in Figure 2, no difference in the X-ray diffraction peak intensities was observed between the LTA zeolites obtained from deAl-FAU&Al(OH) 3 and Ludox HS-40&Al-(OH) 3 , indicating almost the same crystallinity. As shown in Figure 3I,II, 29 Si and 27 Al MAS NMR spectra were also measured to characterize the chemical states of the Si and Al atoms in the framework structures. The 29 Si MAS NMR spectrum of LTA zeolite synthesized from deAl-FAU&Al- Furthermore, the amount of TMA + cations occluded in the framework structure was estimated using TG-DTA analysis.…”

“…Very recently, our group investigated the effect of the Si/Al ratio and crystallinity of the starting FAU zeolite in the interzeolite conversion of FAU-to-AEI and the recrystallization of high-silica FAU zeolite from acid-treated FAU zeolite (dealuminated FAU). , We reported that dealuminated FAU with a high Si/Al ratio has an ordered aluminosilicate structure with a large fraction of 4R units despite its low crystallinity. Thus, this material is easily decomposed/dissolved into aluminosilicate species with 4R units.…”

Rationalization of TS-1 synthesis through the design of experiments

“…It can screen the influence of the experimental variables and their interactions on the result and/or optimize a procedure. The DoE approach was already used to study the synthesis of zeolites, both to explore all the frameworks that can be obtained in a broad range of conditions [25][26][27] and to optimize the synthesis conditions for an already discovered material, in a smaller range of variables. [28][29][30][31][32] Nevertheless, it was never applied to the synthesis of Titanium Silicalite-1 (TS-1), a zeolite whose preparation features many synthetic difficulties, still not unequivocally clarified, beyond the wide literature on the field.…”