A Microporous Aluminosilicate with 12-, 12-, and 8-Ring Pores and Isolated 8-Ring Channels

Abstract

Synthesis of new zeolites with controlled pore architectures is important in the field of catalysis and separation related to chemical transformation, environmental protection, and energy-saving. Zeolites containing channels of different sizes in the same framework have been desirable. We report here the synthesis and structure of a novel aluminosilicate zeolite (designated as YNU-5), the first zeolite containing interconnected 12-, 12-, and 8-ring pores, as well as independent straight 8-ring channels. The synthesis procedure is quite simple and consists of conventional hydrothermal conditions as well as readily available starting materials. The framework structure is stable enough and Si/Al ratio is controllable between 9 and 350. Determination of the crystal structure is performed by utilizing X-ray diffraction-based techniques, revealing 9 independent tetrahedrally coordinated atoms. This robust structure is expected to be industrially valuable and several unusual combinations of composite building units are of considerable interest in an academic sense. The new zeolite YNU-5 is promising catalyst for the production of useful light olefins such as propylene and butylenes in the dimethyl ether-to-olefin reaction, when the Si/Al ratio is properly tuned by dealumination through simple acid treatments.

Development of ZSM-22/Polyethersulfone Membrane for Effective Salt Rejection

“…These features promote high interaction between the polymer and additive as well with the solute cations and anions. Also, their hydrophilic character has earned them their definitive usage as inorganic nanoadditives for composite membrane development [48][49][50][51][52]. This study has therefore identified a need to develop effective materials due to the limited work associated with PES membranes for typical NF or RO applications.…”

The Synthesis of YNU-5 Zeolite and Its Application to the Catalysis in the Dimethyl Ether-to-Olefin Reaction

“…Input amounts were 10.50, 8.70, 6.91, 5.11, 3.31, 1.50, −0.30, and −3.91 g, where w values were 10.0, 9.5, 9.0, 8.5, 8.0, 7.5, 7.0, and 6.0, respectively. The negative values mean that the evaporation of excess water by stirring the mixture at approximately 60 • C on a hot plate [19,21].…”

“…The calcined YNU-5 samples were converted to protonated dealuminated analogues using various acid treatments. Direct dealumination of the calcined YNU-5 (typically 1.0 g) was accomplished by refluxing with 0.1-13.4 mol•L −1 HNO 3 solutions (60 mL (g-sample) −1 ) in a 200 mL round bottom flask at 130 • C in an oil bath for 24 h. These conditions also stabilized the framework of the material due to Si migration [19,21]. The dealuminated versions of YFI-A, B, C, and D are referred to herein as deAl-YFI-A, B, C, and D(n), respectively, where n indicates the Si/Al ratio.…”

“…In our previous paper, we reported a drastic effect of the H 2 O/SiO 2 molar ratio (w) in the starting gel on the resulting zeolitic phases. Specifically, relatively water-rich conditions promoted crystallization of a zeolitic phase with a higher framework density (FD Si [19]), and it was speculated that a more concentrated gel solution enhanced the degree of interaction between the OSDA molecules and the silicate. Further and more detailed investigations of the effects of the H 2 O/SiO 2 molar ratio were performed in the present study.…”

“…Our group has successfully synthesized the new aluminosilicate zeolite YNU-5 having a 12-12-8-ring pore system together with an independent 8-ring system, using dimethyldipropylammonium (Me 2 Pr 2 N + ) as the organic structure-directing agent (OSDA) [19]. This material was given the framework type code YFI by the International Zeolite Association (IZA) [20].…”