Synthesis and characterization of the 12-ring zeolites UZM-4 (BPH) and UZM-22 (MEI) via the charge density mismatch approach in the Choline-Li2O-SrO-Al2O3-SiO2 system

Room-Temperature Synthesis of BPH Zeolite Nanosheets Free of Organic Template with Enhanced Stability for Gas Separations

“…16,17 Alternatively, synthesis procedures using OSDAs in combination with post-synthetic treatments has afforded higher silica variants (UZM-4 and PST-12, Si/Al up to 10). 4,[18][19][20][21] Regarding the particle size, procedures using OSDAs and seed crystals have afforded hexagonal crystals of UZM-4 50-200 nm wide. 22 Here we report the room-temperature and OSDA-free synthesis of BPH (Linde Q) containing a combination of three cations (Cs + , K + and Na + ), yielding nanosheets approximately 7 nm thick and 90 nm across.…”

A Family of Molecular Sieves Containing Framework‐Bound Organic Structure‐Directing Agents

“…)b ridged by oxygen atoms.T he strategies developed to date,i nt he search for such hybrid solids,i nvolve either the direct synthesis using organosilanes containing organic functional groups as a( partial) silica source and alkylammonium-boundo rganosilanes as structure-directing agents, [2] or the post-synthetic treatment using similar organosilane species as pillaring or silylating agents. [3] Thus,t hey rely on the use of organic species which already contain an atom susceptible of incorporation as atetrahedral atom (T-atom) in the zeolitic framework.Thes ynthesis of ECR-40, first reported as as ilicoaluminophosphate (SAPO) molecular sieve with the MEI topology in 1999, includes the use of either tris(2-hydroxyethyl)methylammonium (THMA + )orbis(2-hydroxyethyl)dimethylammonium (BHDMA + )i ons as organic structure-directing agents (OSDAs).[4] Our interest in this material began with the unexpected gauche conformation of (2-hydroxyethyl)trimethylammonium (HTMA + )i ons within as-made UZM-22, an MEI-type aluminosilicate zeolite, [5] stabilized by one intramolecular hydrogen bond between the oxygen atom of its OH group and the hydrogens of carbon atoms linked to the charged nitrogen center.[6] Like HTMA + ,b oth THMA + and BHDMA + contain polar OH groups which can participate not only in intramolecular CÀH···O hydrogen bonding,b ut also in intermolecular hydrogen bonding to the other OSDA molecules or to the molecular sieve framework. Moreover, ECR-40 was deemed to be isostructural with ZSM-18, the type material for MEI, containing odd-membered rings,such as 5-rings,w hich are usually absent in tetrahedral aluminophosphate-based frameworks [7] because of Loewensteins rule,that is,the avoidance of tetrahedral Al-O-Al linkages.…”

A Family of Molecular Sieves Containing Framework‐Bound Organic Structure‐Directing Agents

“…ECR-40 crystallization begins with the formation of an Al-OSDAc omplex in the liquid phase in which the Al is octahedrally coordinated. [4] Our interest in this material began with the unexpected gauche conformation of (2-hydroxyethyl)trimethylammonium (HTMA + )i ons within as-made UZM-22, an MEI-type aluminosilicate zeolite, [5] stabilized by one intramolecular hydrogen bond between the oxygen atom of its OH group and the hydrogens of carbon atoms linked to the charged nitrogen center. Subsequent removal of frameworkbound OSDAs generates Al-O-Al linkages in af ully tetrahedrally coordinated framework.…”

“…[4] Our interest in this material began with the unexpected gauche conformation of (2-hydroxyethyl)trimethylammonium (HTMA + )i ons within as-made UZM-22, an MEI-type aluminosilicate zeolite, [5] stabilized by one intramolecular hydrogen bond between the oxygen atom of its OH group and the hydrogens of carbon atoms linked to the charged nitrogen center. [4] Our interest in this material began with the unexpected gauche conformation of (2-hydroxyethyl)trimethylammonium (HTMA + )i ons within as-made UZM-22, an MEI-type aluminosilicate zeolite, [5] stabilized by one intramolecular hydrogen bond between the oxygen atom of its OH group and the hydrogens of carbon atoms linked to the charged nitrogen center.…”

“…[3] Thus,t hey rely on the use of organic species which already contain an atom susceptible of incorporation as atetrahedral atom (T-atom) in the zeolitic framework.Thes ynthesis of ECR-40, first reported as as ilicoaluminophosphate (SAPO) molecular sieve with the MEI topology in 1999, includes the use of either tris(2-hydroxyethyl)methylammonium (THMA + )orbis(2-hydroxyethyl)dimethylammonium (BHDMA + )i ons as organic structure-directing agents (OSDAs). [4] Our interest in this material began with the unexpected gauche conformation of (2-hydroxyethyl)trimethylammonium (HTMA + )i ons within as-made UZM-22, an MEI-type aluminosilicate zeolite, [5] stabilized by one intramolecular hydrogen bond between the oxygen atom of its OH group and the hydrogens of carbon atoms linked to the charged nitrogen center. [6] Like HTMA + ,b oth THMA + and BHDMA + contain polar OH groups which can participate not only in intramolecular CÀH···O hydrogen bonding,b ut also in intermolecular hydrogen bonding to the other OSDA molecules or to the molecular sieve framework.…”