Structural investigations in pure-silica and Al-ZSM-12 with MTEA or TEA cations

Abstract

Two different quaternary ammonium cations, methyltriethyl-(MTEA) and tetraethylammonium cations (TEA) were used as templates in the synthesis of puresilica as well as aluminosilicate ZSM-12 (MTW-type) frameworks. The distribution of the template cations in the 12MR channels in the 1-dimensional framework topology was studied; thus the as-prepared products were characterized by means of X-ray powder diffraction, Raman, transmission FTIR, solid-state NMR spectroscopy, thermogravimetric and elemental analyses and SEM. Recently, it was shown that in pure-silica (PS) ZSM-12, TEA cations are well ordered-a superstructure with threetimes longer b edge along the channel is formed, which can be seen by virtue of a few additional peaks in the X-ray powder pattern. Herein we describe that its aluminosilicate counterpart with TEA also contains ordered TEA cations and is isostructural to PS-ZSM-12. Conversely, in both pure-silica and aluminosilicate ZSM-12 frameworks with MTEA, the cations are disordered and no superstructure is formed.

Catalytic conversion of glucose in fructose utilizing high-silica zeolite Sn-ZSM-12

“…However, their samples have different chemical compositions than those synthesized in our study. Results similar to those obtained in our study were reported in [25] even for samples of different chemical composition and obtained with others crystallization time. The analysis of the TG curves of the samples of Sn-ZSM-12 containing different tin concentrations indicated that the addition of tin occasioned reduction in the total mass loss (Table I) probably due to the increase in structural defects caused by the incorporation of tin in the structure.…”

Effect of use of methyltriethylamonium chloride individually and combined with n-butylamine on the characteristics of the ZSM-12 zeolite crystallization process

“…ZSM-12 is usually synthesized from quaternary ammonium salts, which are involved in the formation of the aluminosilicate porous structure and affect the characteristics of the resulting material. Thus, a significant number of reports have focused on the study of nucleation and growth of crystals of this zeolite in the presence of various organic ammonium salts, such as methyltriethylammonium and N,N-dimethyl-N-ethyl(monoethanol)ammonium (Kulikov et al, 2019), tetraethylammonium (Toktarev & Ione, 1997;Kasunič et al, 2009), trimethylethylammonium (Počkaj et al, 2018), imidazole, pyridine and piperidine salts (Kore, R. & Srivastava, 2012), and diquaternary ammonium salts (Moini et al;1994;Han et al, 2005;Veselý et al, 2019).…”