Intergrown Zeolite MWW Polymorphs Prepared by the Rapid Dissolution–Recrystallization Route

Abstract

Zeolites with intergrown structures are particularly interesting because they often exhibit unique performance in heterogeneous catalysis. This raises the bar of the structural characterizations and remains an enormous challenge to understand the synthesis conditions and the formation mechanisms of such intergrown materials. Herein, a novel intergrown zeolite (ECNU-5) was successfully synthesized via a rapid dissolution–recrystallization (RDR) route, which reorganized the conventional MWW layer stacking into two new different polymorphs, ECNU-5A and ECNU-5B. Structure elucidation indicates both polymorphs are reconstructed from the same MWW layer but are different in relative shift between adjacent layers. ECNU-5 is the first structure-determined zeolite with interrupted structure that MWW layers shift in the horizontal direction, in which the two polymorphs are never predicted before and are additional members of the MWW family. The unique geometry mismatch between the organic structure-directing agent (OSDA) and inorganic silicate framework is ascribed to causing the zeolite layer shift. Moreover, the implementation of silylation technique readily expanded the interlayer pore of as-made ECNU-5, producing the interlayer-expanded zeolite (IEZ-ECNU-5), which maintained the original stacking sequence of MWW sheets.

Building Zeolites from Precrystallized Units: Nanoscale Architecture

“…Thewelldefined external surface area together with the larger number of cups in ITQ-2 give the material al arger number of structurally accessible acid sites,w hich results in superior catalytic activity in al arge number of reactions. [98] Through the RDR treatment, the sinusoidal 10-ring channel was well-preserved while the interlayer channel system was transformed into az igzag shape.T he geometry mismatch between the OSDA, 1,3-bis(cyclohexyl) imidazolium, and the zeolite framework is ascribed as the reason for such alayer shift of the zeolite.Onthe other hand, Fane tal. [98] Through the RDR treatment, the sinusoidal 10-ring channel was well-preserved while the interlayer channel system was transformed into az igzag shape.T he geometry mismatch between the OSDA, 1,3-bis(cyclohexyl) imidazolium, and the zeolite framework is ascribed as the reason for such alayer shift of the zeolite.Onthe other hand, Fane tal.…”

Bridging the Gap between Structurally Distinct 2D Lamellar Zeolitic Precursors through a 3D Germanosilicate Intermediate

“…[7,14] As tarting zeolite containing specific structure features can facilitate crystal nucleation and growth of other zeolites sharing similar features;h owever, interzeolite transformations,w hich are widely used in the synthesis of aluminosilicates,h ave not been applied to germanosilicates. [7,14] As tarting zeolite containing specific structure features can facilitate crystal nucleation and growth of other zeolites sharing similar features;h owever, interzeolite transformations,w hich are widely used in the synthesis of aluminosilicates,h ave not been applied to germanosilicates.…”

Recent Advances in the Synthesis and Application of Two‐Dimensional Zeolites

“…[ 7,8 ] The mww layer with a thickness of 2.5 nm has a sinusoidal 10-membered ring (MR) channel within the ab plane, while a number of terminal hydroxyl groups connected to the crystallographic T6 site exisit on layer surface. [ 22 ] In fact, the stacking patterns of zeolite layers were infl uenced by many factors, such as the concentration and distribution of surface silanols, the interactions between neighboring inorganic layers and the types of OSDA involved within the interlayer void. [ 8 ] As the 3D form of MWW structure (MCM-49) could also be directly prepared, [ 63 ] the precursor MCM-22P with a 2D feature is unique because the mww layers are regularly packed through the hydrogen-bond (H-bond) interaction between surface silanols.…”

“…[ 8 ] As the 3D form of MWW structure (MCM-49) could also be directly prepared, [ 63 ] the precursor MCM-22P with a 2D feature is unique because the mww layers are regularly packed through the hydrogen-bond (H-bond) interaction between surface silanols. [ 22 ] The dirving force to cause the mww layer shifting may be originated from the confi guration mismatch between the cyclohexyl groups of ERB-1P piperidine [ 18 ] ITQ-1P trimethyladamantammonium [ 19 ] Ti-MWW HMI or piperidine [ 20,21 ] ECNU-5P 1,3-bis(cyclohexyl)imidazolium [ 22 ] EMM-10P bis(N,N,N-trimethyl)-1,5-pentanediamonium [ 23 ] SSZ-70 substituted imidazoliums [ 24,25 ] MCM-56 hexamethyleneimine, Na + [ 26,27 ] ITQ-30 N(16)-methyl-sparteinium [ 28 ] fer PREFER 4-amino-tetramethylpiperidinium [ 9 ] PLS-3 tetraethylammonium [ 29 ] PLS-1 tetramethylammonium, K + [ 30 ] PLS-4 diethyldimethylammonium [ 29 ] RUB-36 diethyldimethylammonium [ 31 ] RUB-38 methyltriethylammonium [ 31 ] RUB-48 diethyldimethylammonium [ 31 ] MCM-65 quinuclidine, tetramethylammonium [ 32 ] UZM-13 diethyldimethylammonium [ 33 ] RUB-20 tetramethylammonium [ 31 ] RUB-40 tetramethylphosphonium [ 31 ] ERS-12 tetramethylammonium [ 34 ] MCM-47 tetramethylene-bis(N-methylpyrrolidinium) [ 35 ] mfi Self-pillared pentasil tetrabutylphosphonium/tetrabutylammonium [ 36 ] cas Nu-6(1) 4,4′-bipyridinium [ 37 ] EU-19 piperazinium [ 38 ] heu CIT-8P substituted diquaternary imidazoles [ 39 ] RUB-39 dimethyldipropylammonium [ 40 ] ast HUS-1 tetramethylammonium [ 41 ] RUB-55 tetramethylammonium [ 42 ] sod RUB-15 tetramethylammonium …”

“…Generally, the perfect crystal structure of fer layers, nature of OSDA and interaction between adjacent layers are regarded as the key factors in the formation of a well-ordered microporous framework. [ 22 ] Copyright 2015, American Chemical Society. Energy Mater.…”