scholarly journals Gallery character of porous space in the STI-type zeolite structure

2021 ◽  
Vol 82 (3) ◽  
pp. 28-30
Author(s):  
Tsveta Stanimirova ◽  
Georgi Kirov
Keyword(s):  
Layered Structure ◽  
Aluminum Silicate ◽  
Water Molecules ◽  
Porous Space ◽  
Zeolite Framework ◽  
Zeolite Structure ◽  
Exchange Cations ◽  
Type Zeolite ◽  
Silicate Layers ◽  
Gallery Type

The existence of a specific gallery type of zeolite framework is confirmed. It has been found that similar to HEU-type, STI-type framework can be represented as a layered structure in which two impermeable to water molecules and exchange cations aluminum-silicate layers, separated by diortho-groups, confined gallery-type of porous free space, which is available for extra-framework components migration in all directions in the plane of the interlayer.

Theoretical characterization of zeolite encapsulated platinum clusters in the presence of water molecules

2021 ◽  
Author(s):  
Qianqian Bao ◽  
Weiwei Zhang ◽  
Donghai Mei
Keyword(s):  
Dft Calculations ◽  
Metal Clusters ◽  
Water Molecules ◽  
Zeolite Framework ◽  
Platinum Clusters ◽  
Type Zeolite ◽  
Theoretical Characterization

From the DFT calculations, we found the MFI-type zeolite encapsulated Pt metal clusters shows superior stability. The presence of water molecules enhances the interaction between the zeolite framework and the metal clusters, making the configuration more stable.

scholarly journals The Layered Structure of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2O

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Nitrogen Atom ◽  
Single Crystals ◽  
Silica Gel ◽  
Layered Structure ◽  
Water Molecules ◽  
Two Dimensional ◽  
Space Group ◽  
Distorted Octahedral ◽  
Oxygen Atoms

Triclinic single crystals of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2O have been grown in anaqueous silica gel. Space group P-1 (Nr. 2), a = 723.94(7) pm, b = 813.38(14) pm, c = 931.0(2) pm, α = 74.24(2)°, β = 79.24(2)°, γ = 65.451(10)°, V = 0.47819(14) nm3, Z = 1. Cu2+ is coordinated in a distorted, octahedral manner by two water molecules, three oxygen atoms ofthe pyromellitate anions and one nitrogen atom of pyrazine (Cu—O 194.1(2)–229.3(3) pm;Cu–N 202.0(2) pm). The connection of Cu2+ and [C6H2(COO)4)]4− yields infinite strands,which are linked by pyrazine molecules to form a two-dimensional coordination polymer.Thermogravimetric analysis in air showed that the dehydrated compound was stable between175 and 248 °C. Further heating yielded CuO.

scholarly journals Rerefinement of poly[diaquabis(μ3-2-methylpropanoato-κ4 O:O,O′:O′)bis(μ3-2-methylpropanoato-κ3 O:O:O)(μ2-2-methylpropanoato-κ3 O:O,O′)(2-methylpropanoato-κ2 O,O′)trilead(II)]

IUCrData ◽  
2020 ◽  
Vol 5 (10) ◽  
Author(s):  
Erika Samolová ◽  
Jan Fábry
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Layered Structure ◽  
Title Complex ◽  
Water Molecules ◽  
X Ray ◽  
Positional Disorder ◽  
Coordination Numbers ◽  
Carboxylate Groups ◽  
Accuracy And Precision

The crystal structure of the title complex, [Pb3(C4H7O2)6(H2O)2] n , was redetermined on basis of modern CCD-based single-crystal X-ray data at 120 K. The current study basically confirms the previous report [Fallon et al. (1997). Polyhedron, 16, 19–23] at 190 K, but with higher accuracy and precision. In particular, positional disorder of one of the 2-methylpropanoate anions over two sets of sites was resolved, showing a refined ratio of the disorder components of 0.535 (9):0.465 (9). The three independent cations in the structure have coordination numbers of [7 + 1], [6 + 1], and [5 + 3], with O atoms belonging either to carboxylate groups or water molecules. This arrangement leads to the formation of sheets parallel to (\overline{1}01), whereby the hydrophobic 2-methylpropanyl groups of the anions are oriented above and below the hydrophilic sheets to form a layered structure. Within a sheet, hydrogen bonds of the type Owater—H...O are formed, whereas the hydrophobic groups between adjacent layers interact through van der Waals forces.

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.

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