Gas adsorption by a crystalline silicic acid

1989 ◽  
Vol 267 (9) ◽  
pp. 844-852 ◽  
Author(s):  
H. -H. Kruse ◽  
K. Beneke ◽  
G. Lagaly
Keyword(s):  
Silicic Acid ◽  
Gas Adsorption ◽  
Crystalline Silicic Acid

scholarly journals Über die Natur der Siliciumdioxidmodifikation Silica-X / On the Nature of the Silica Modification "silica-X"

1979 ◽  
Vol 34 (4) ◽  
pp. 648-649 ◽  
Author(s):  
Klaus Beneke ◽  
Gerhard Lagaly
Keyword(s):  
Cation Exchange ◽  
Silicic Acid ◽  
Potassium Silicate ◽  
Silica Modification ◽  
Crystalline Silicic Acid

Abstract Silica-X described in 1964 as a new SiO2 modification is the dehydrated form of the crystalline silicic acid H2Si8O17 · xH2O which is obtained by cation exchange from the potassium silicate K2Si8O17 · xH2O.

Silylation of a crystalline silicic acid: an MAS NMR and porosity study

2002 ◽  
Vol 12 (10) ◽  
pp. 3010-3015 ◽  
Author(s):  
Peter Heinrich Thiesen ◽  
Klaus Beneke ◽  
Gerhard Lagaly
Keyword(s):  
Silicic Acid ◽  
Mas Nmr ◽  
Crystalline Silicic Acid

Über eine neue kristalline Kieselsäure der Zusammensetzung H2Si14O29 · 5 H2O mit Schichtstruktur und Befähigung zur Bildung von Intercalationsverbindungen / A Crystalline Silicic Acid H2Si14O29 · 5 H2O with Layer Structure and Capability of Formation of Intercalation Compounds

1973 ◽  
Vol 28 (5-6) ◽  
pp. 234-238 ◽  
Author(s):  
Gerhard Lagaly ◽  
Klaus Beneke ◽  
Armin Weiss
Keyword(s):  
Sodium Silicate ◽  
Silicic Acid ◽  
Layer Structure ◽  
Intercalation Compounds ◽  
Two Dimensional ◽  
Topochemical Reaction ◽  
Crystalline Silicic Acid

A crystalline silicic acid H2Si14O29 · 5H2O has been prepared by topochemical reaction of sodium silicate Na2Si14O29·12H2O with acids. The compound has a layer structure with silicate sheets of about 11.2 Å thickness. The layer structure is clearly established by two dimensional reactions, mainly the formation of intercalation compounds with X-oxides (dimethylsulfoxide, pyridine-N-oxides etc.), acid amides, urea and its derivatives and bases such as hydrazine and pyridine. Typical exemples are 2 (CH3)2SO · H2Si14O29, 2C5H5NO · H2Si14O29, 2, 7 HCONHCH3 · H2Si14O29; 2, 3 HCON (CH3)2 · H2Si14O29; 1, 6 HCONHC2H5 · H2Si14O29; 1, 6 HCON (C2H5)2 · H2Si14O29.

scholarly journals Preparation and constitution of the Crystalline Silicic Acid Trimethylsilyl Ester [(CH3)3Si]6Si6O15

1987 ◽  
Vol 552 (9) ◽  
pp. 236-240 ◽  
Author(s):  
D. Hoebbel ◽  
G. Engelhardt ◽  
A. Samoson ◽  
K. �jsz�szy ◽  
Yu. I. Smolin
Keyword(s):  
Silicic Acid ◽  
Trimethylsilyl Ester ◽  
Crystalline Silicic Acid

Adsorption of alkylamines by a crystalline silicic acid

Clay Minerals ◽  
1993 ◽  
Vol 28 (1) ◽  
pp. 39-48 ◽  
Author(s):  
J. Döring ◽  
G. Lagaly
Keyword(s):  
Silicic Acid ◽  
Adsorption Isotherms ◽  
Equilibrium Solution ◽  
Molar Fraction ◽  
Basal Spacing ◽  
Surface Excess ◽  
Adsorption Phase ◽  
Interlamellar Space ◽  
Crystalline Silicic Acid ◽  
Reduced Surface

AbstractAmines are strongly adsorbed by the crystalline silica H4Si20O42·4H2O and are intercalated into the interlayer spaces. The adsorption of butyl-, hexyl-, octyl-, and decylamine from alcoholic solutions (ethanol, butanol…decanol) is competitive as both types of molecules, amines and alcohols, are adsorbed in the interlamellar space. The adsorption isotherms are presented as composite isotherms showing the specific reduced surface excess of amine, n°(n)/m, as a function of the molar fraction of amine in the equilibrium solution. These isotherms increase to a plateau-like section (n°(n)/m≈1·4 mmol/g) when the interlamellar adsorption is restricted to formation of monolayers of flat-lying molecules (in water, ethanol and butanol). In the presence of longer chain alcohols, the isotherms increase stepwise to a second "plateau" (at n1°(n)/m = 2·2-2·7 mmol/g) which corresponds to paraffin-type bilayers of amine and alcohol molecules. The composition of the adsorption phase is estimated from the specific reduced surface excess of amine on the basis of the interlamellar structure derived from basal spacing measurements.

ChemInform Abstract: Preparation and Constitution of the Crystalline Silicic Acid Trimethylsilyl Ester ((CH3)3Si)6Si6O15.

ChemInform ◽  
1988 ◽  
Vol 19 (9) ◽  
Author(s):  
D. HOEBBEL ◽  
G. ENGELHARDT ◽  
A. SAMOSON ◽  
K. UJSZASZY ◽  
YU. I. SMOLIN
Keyword(s):  
Silicic Acid ◽  
Trimethylsilyl Ester ◽  
Crystalline Silicic Acid

scholarly journals Oligomerization of Silicic Acids in Neutral Aqueous Solution: A First-Principles Investigation

2019 ◽  
Vol 20 (12) ◽  
pp. 3037 ◽  
Author(s):  
Xin Liu ◽  
Cai Liu ◽  
Changgong Meng
Keyword(s):  
Aqueous Solution ◽  
Silicic Acid ◽  
First Principles ◽  
Gas Adsorption ◽  
Industrial Applications ◽  
Hydrothermal Processes ◽  
Neutral Aqueous Solution ◽  
Reaction Barriers ◽  
Silicic Acids ◽  
Kinetic Selectivity

Crystallite aluminosilicates are inorganic microporous materials with well-defined pore-size and pore-structures, and have important industrial applications, including gas adsorption and separation, catalysis, etc. Crystallite aluminosilicates are commonly synthesized via hydrothermal processes, where the oligomerization of silicic acids is crucial. The mechanisms for the oligomerization of poly-silicic acids in neutral aqueous solution were systematically investigated by extensive first-principles-based calculations. We showed that oligomerization of poly-silicic acid molecules proceeds through the lateral attacking and simultaneously proton transfer from the approaching molecule for the formation of a 5-coordinated Si species as the transition state, resulting in the ejection of a water molecule from the formed poly-silicic acid. The barriers for this mechanism are in general more plausible than the conventional direct attacking of poly-silicic acid with reaction barriers in the range of 150–160 kJ/mol. The formation of linear or branched poly-silicic acids by intermolecular oligomerization is only slightly more plausible than the formation of cyclic poly-silicic acids via intramolecular oligomerization according to the reaction barriers (124.2–133.0 vs. 130.6–144.9 kJ/mol). The potential contributions of oligomer structures, such as the length of the linear oligomers, ring distortions and neighboring linear branches, etc., to the oligomerization were also investigated but found negligible. According to the small differences among the reaction barriers, we proposed that kinetic selectivity of the poly-silicic acids condensation would be weak in neutral aqueous solution and the formation of zeolite-like structures would be thermodynamics driven.

Notizen:Kernmagnetische Relaxationszeit-Messungen an OH-Protonen einer kristallinen Kieselsäure/ Nuclear Magnetic Relaxation Measurements on the OH-Protons of a Crystalline Silicic Acid

1975 ◽  
Vol 30 (10) ◽  
pp. 1330-1332 ◽  
Author(s):  
E. K.-H. Wittich ◽  
J. Voitländer ◽  
G. Lagaly
Keyword(s):  
Thermal Decomposition ◽  
Silicic Acid ◽  
Magnetic Relaxation ◽  
Interlayer Space ◽  
Relaxation Times ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Relaxation Measurements ◽  
Silicate Layers ◽  
Crystalline Silicic Acid

Abstract The transversal relaxation times of the OH-protons of a crystalline silicic acid were measured. Two relaxation processes, clearly separated from each other, are related to the OH-protons in the silicate layers and to the OH-protons of water molecules in the interlayer spaces. From the initial magnetizations information is obtained about the water content in the interlayer space which does well agree with results given in thermal decomposition curves.

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