Use of Flexible Diquaternary Structure-directing Agents in Zeolite Synthesis: Discovery of Zeolites TNU-9 and TNU-10 and Their Catalytic Properties

Hong, Suk Bong

doi:10.1007/s10563-008-9045-5

Cited by 25 publications

(13 citation statements)

References 48 publications

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“…Also, a dual specificity might be related, possibly, to a change in conformation of the OSDA or to a change in the OSDA-OSDA interactions, leading to a different structural direction effect. The group of S. B. Hong at POSTECH has provided abundant examples, in which the specificity of a flexible OSDA can be tuned by modifying the inorganic components of the reaction mixture and their concentrations, to the point of establishing the conformational control of highly flexible OSDAs as an alternative strategy for the discovery of new zeolites. − However, the conformation of our OSDA in IDM-1 and MFI is not radically different. We believe that further studies on these two systems might give clues for a better understanding of the relationship between crystallization parameters and intergrowths.…”

Section: Resultsmentioning

confidence: 99%

Sandwich-Type Zeolite Intergrowths with MFI and the Novel Extra-Large Pore IDM-1 as Ordered End-Members

Villaescusa

Mayoral

et al. 2021

Chem. Mater.

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Stacking faults are two-dimensional planar defects frequently arising in zeolites, modifying their properties and potentially affecting their performance in catalysis and separation applications. In classical zeolite intergrowths, a topologically unique zeolite layer may often pile up after some spatial transformation (lateral translation, rotation, and/or reflection) that may occur in different amounts or directions with about similar probabilities, leading to a difficult to control disorder. Here, we present a new kind of zeolite intergrowth that requires an additional topologically distinct layer rather than a spatial transformation of a unique one. Stacking of the so-called pentasil layers produces the well-known medium pore zeolite MFI. Intercalation in strict alternation of a topologically distinct second layer sandwiched between pentasil layers expands the structure to produce the new extra-large pore IDM-1. Stacking disorder modulates the structural expansion along the stacking direction. The disordered materials have been studied by simulation of the X-ray diffraction patterns using the program DIFFaX and by Cs-corrected high-resolution electron microscopy. We show that disorder does not occur at random but in extended domains and can be controlled all the way from MFI to IDM-1 by just varying the concentration of the synthesis mixture.

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Section: Resultsmentioning

confidence: 99%

Sandwich-Type Zeolite Intergrowths with MFI and the Novel Extra-Large Pore IDM-1 as Ordered End-Members

Villaescusa

Mayoral

et al. 2021

Chem. Mater.

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“…In addition, the fact that the gel composition range yielding pure PST‐31 with abundant odd‐membered rings is narrow (Tables S1 and S2) suggests that the structure‐directing effect of 14DMP‐C 4 2+ may be specific rather than strong. This is because the conformation of flexible OSDAs, which affects the phase selectivity of the crystallization, can be altered by the type and concentration of inorganic components in synthesis mixtures [19] …”

Section: Resultsmentioning

confidence: 99%

“…This is because the conformation of flexible OSDAs,w hich affects the phase selectivity of the crystallization, can be altered by the type and concentration of inorganic components in synthesis mixtures. [19] From as tructural point of view,o nt he other hand, we were aware that the tetrahedrality of the resulting structures could be maintained, although the interlayer s4r units in PST-31 are eliminated or replaced by d4r units ( Figure S15). The same result was obtained when the symmetry operations relating the two adjacent PST-31 layers are other than translation along the caxis (i.e., translation along b-axis, reflection, and glide reflection).…”

Section: +mentioning

confidence: 99%

An Aluminosilicate Zeolite Containing Rings of Tetrahedral Atoms with All Odd Numbers from Five to Eleven

Zhang

Lee

et al. 2021

Angewandte Chemie

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Herein we report the synthesis, structure solution, and catalytic properties of PST‐31, which has an unprecedented framework topology. This high‐silica (Si/Al=16) zeolite was synthesized using a pyrazolium‐based dication with a tetramethylene linker as an organic structure‐directing agent (OSDA) in hydroxide media. The PST‐31 structure is built from new building layers containing four‐, five‐, six‐, and seven‐membered rings, which are connected by single four‐membered rings in the interlayer region to form a two‐dimensional pore system. Its channels consist of [4.56.6.9.11] and [5.6.7.9.10.11] cavities and are thus delimited by nine‐, ten‐, and eleven‐membered rings. The OSDA cations in as‐synthesized PST‐31 were determined to reside without disorder in the large [42.514.64.72.94] cavities composed of smaller [4.56.6.9.11] and [5.6.7.9.10.11] ones, leading to a symmetry coincidence between the OSDA and the surrounding zeolite cavity. The proton form of PST‐31 was found to be selective for the cracking of n‐hexane to light olefins.

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“…An excellent example of the latter is a recent study that observes the effects of hydroxide concentration on syntheses performed using 1,4-bis(N-methylpyrrolidinium) butane as an SDA [9]. At a constant Si/Al ratio of 30, ZSM-12 (MTW) was produced from gels having a OH − /Si ratio ≤ 0.6, TNU-9 (TUN, a new 10-ring zeolite having a three-dimensional channel framework similar to ZSM-5) was produced from gels having a OH − /Si ratio = 0.73 and TNU-10 (a new high silica form of stilbite, STI) was produced from gels having a OH − /Si ratio = 1.0.…”

Section: Mineralizersmentioning

confidence: 99%

Synthesis Approaches

Strohmaier

2010

Zeolites and Catalysis

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Zeolites were first identified as natural minerals having unique physical absorption properties. Early researchers tried to reproduce the geological conditions in an attempt to make them synthetically. From the years 1845 to 1937 many researchers investigated the hydrothermal conversion and synthesis of silicates. Although there were a number of claims that zeolites had been made synthetically, they were unsubstantiated as identification was based upon chemical analysis and optical observations. Later attempts at reproducing these early experiments did not give identifiable zeolites. It was not until the 1940s that Professor Richard M. Barrer found the necessary conditions for making zeolites synthetically and he identified them by powder X-ray diffraction. By reacting the powder minerals leucite and analcime with aqueous solutions of barium chloride at temperatures of 180-270 • C for two to six days, a synthetic chabazite was obtained. In 1948, Professor Barrer was able to synthesize zeolites entirely from synthetic solutions of sodium aluminate, silicic acid, and sodium carbonate [1]. A dry powdered gel was first obtained by drying the mixture at 110 • C, and then crystallizing it to a synthetic mordenite by reacting the gel with water at higher temperatures. In the 1950s, Donald Breck and researchers at the Union Carbide Company began to synthesize zeolites from reactive aluminosilicate gels prepared from sodium aluminate and sodium silicate solutions. This led directly to the discovery of the first two new synthetic zeolites, Linde A [2] and Linde X (Si/Al = 1.0-1.5) [3], both having new framework structures, LTA and FAU, respectively. Linde A was found to have excellent ion exchange and gas separation properties. Later, a new, higher silica containing composition of FAU, designated Linde Y [4] (Si/Al = 1.5-3.0), was synthesized and was found to be an excellent cracking catalyst for the conversion of distilled crude oil to gasoline products. The discovery of these two industrially important zeolites caught the attention of many scientists and kick started the field of zeolite synthesis research.

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Use of Flexible Diquaternary Structure-directing Agents in Zeolite Synthesis: Discovery of Zeolites TNU-9 and TNU-10 and Their Catalytic Properties

Cited by 25 publications

References 48 publications

Sandwich-Type Zeolite Intergrowths with MFI and the Novel Extra-Large Pore IDM-1 as Ordered End-Members

Sandwich-Type Zeolite Intergrowths with MFI and the Novel Extra-Large Pore IDM-1 as Ordered End-Members

An Aluminosilicate Zeolite Containing Rings of Tetrahedral Atoms with All Odd Numbers from Five to Eleven

Synthesis Approaches

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