Transcription-induced formation of paired Al sites in high-silica CHA-type zeolite framework using Al-rich amorphous aluminosilicate

2021 ◽  
Author(s):  
Mizuho Yabushita ◽  
Yoshiyasu Imanishi ◽  
Ting Xiao ◽  
Ryota Osuga ◽  
Toshiki Nishitoba ◽  
...  
Keyword(s):  
Hydrothermal Conditions ◽  
Zeolite Framework ◽  
New Approach ◽  
Type Zeolite ◽  
High Silica ◽  
Amorphous Aluminosilicate

The paired Al species pre-formed in Al-rich amorphous aluminosilicates were transcribed into high-silica CHA-type zeolite frameworks under hydrothermal conditions, which offers a new approach to creating paired Al sites in...

scholarly journals Gas Permeation Properties of High-Silica CHA-Type Zeolite Membrane

Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 249
Author(s):  
Yasuhisa Hasegawa ◽  
Chie Abe ◽  
Mayumi Natsui ◽  
Ayumi Ikeda
Keyword(s):  
Molecular Size ◽  
Gas Permeation ◽  
Zeolite Membrane ◽  
Type Zeolite ◽  
High Silica ◽  
Separation Of Co2 ◽  
Α Al2o3 ◽  
Separation Performances ◽  
Molecular Sieving ◽  
Permeation Properties

The polycrystalline CHA-type zeolite layer with Si/Al = 18 was formed on the porous α-Al2O3 tube in this study, and the gas permeation properties were determined using single-component H2, CO2, N2, CH4, n-C4H10, and SF6 at 303–473 K. The membrane showed permeation behavior, wherein the permeance reduced with the molecular size, attributed to the effect of molecular sieving. The separation performances were also determined using the equimolar mixtures of N2–SF6, CO2–N2, and CO2–CH4. As a result, the N2/SF6 and CO2/CH4 selectivities were as high as 710 and 240, respectively. However, the CO2/N2 selectivity was only 25. These results propose that the high-silica CHA-type zeolite membrane is suitable for the separation of CO2 from CH4 by the effect of molecular sieving.

Diffusion of phenolic compounds within high-silica MFI-type zeolite in the mesitylene solution

2021 ◽  
Vol 319 ◽  
pp. 111044
Author(s):  
Xinluona Su ◽  
Yuta Nakasaka ◽  
Ren Moriwaki ◽  
Takuya Yoshikawa ◽  
Takao Masuda
Keyword(s):  
Phenolic Compounds ◽  
Type Zeolite ◽  
High Silica

Precise control of density and strength of acid sites of MFI-type zeolite nanoparticles via simultaneous isomorphous substitution by Al and Fe

CrystEngComm ◽  
2020 ◽  
Vol 22 (44) ◽  
pp. 7556-7564
Author(s):  
Mizuho Yabushita ◽  
Hiroki Kobayashi ◽  
Atsushi Neya ◽  
Masafumi Nakaya ◽  
Sachiko Maki ◽  
...  
Keyword(s):  
Acid Sites ◽  
Linear Control ◽  
Isomorphous Substitution ◽  
Zeolite Framework ◽  
Precise Control ◽  
Type Zeolite ◽  
Catalyst Lifetime

The co-incorporation of Al and Fe at various relative ratios into the MFI-type zeolite framework enabled linear control of the density and strength of acid sites, and such well-tuned acidity led to a better catalyst lifetime.

scholarly journals Hierarchical Low Si/Al Ratio Ferrierite Zeolite by Sequential Postsynthesis Treatment: Catalytic Assessment in Dehydration Reaction of Methanol

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Enrico Catizzone ◽  
Massimo Migliori ◽  
Alfredo Aloise ◽  
Rossella Lamberti ◽  
Girolamo Giordano
Keyword(s):  
Textural Properties ◽  
Vapour Phase ◽  
Solution Concentration ◽  
Methanol Conversion ◽  
Molar Ratio ◽  
Light Hydrocarbons ◽  
Hierarchical Zeolites ◽  
Type Zeolite ◽  
High Silica ◽  
High Silica Zeolites

In contrast to high silica zeolites, it is difficult to obtain mesoporosity in zeolites with low Si/Al ratio (e.g., <20) via conventional NaOH-based treatment, making the obtainment of hierarchical zeolites with high acidity a challenging target. In this paper, we report the preparation of hierarchical FER-type zeolite at low Si/Al molar ratio (about 10) by postsynthesis etching involving a sequence of three treatments with NaAlO2, HCl, and NaOH solutions and investigate the effect of both NaAlO2 solution concentration and time of treatment on the textural properties. The obtained materials exhibit a mesoporous volume higher than the parent ferrierite with no significant effect on the sample acidity. The catalytic activity of some samples was investigated in vapour-phase methanol dehydration to dimethyl ether, revealing the superiority of hierarchical zeolites in terms of methanol conversion, although the presence of mesopores causes formation of light hydrocarbons at high temperatures.

Sign in / Sign up

Export Citation Format

Share Document