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HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES . Typical zeolite synthesis NaAl(OH) 4 (aq) + Na 2 SiO 3 (aq) + NaOH(aq), 25 o C, condensation-polymerization, Na(H 2 O) n + template 

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hydrothermal synthesis and crystallization of zeolites
HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES
  • Typical zeolite synthesis
  • NaAl(OH)4(aq) + Na2SiO3(aq) + NaOH(aq), 25oC, condensation-polymerization, Na(H2O)n+ template 
  • Naa(AlO2)b(SiO2)c.NaOH.H2O(gel)  25-175oC, hydrothermal crystallization of amorphous gel
  • Nax(AlO2)x(SiO2)y.zH2O(crystals)
hydrothermal synthesis and crystallization of zeolites2
HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES
  • Nax(AlO2)x(SiO2)y.zH2O(crystals)
  • Extraframework charge-balancing cations, templates, ion-exchangeable
  • Framework Al(III)O4 and Si(IV)O4 tetrahedral primary building-blocks
  • (AlO2)- and SiO2 stoichiometry for building blocks as bridging O
  • Occluded water, removed by 25-500oC vacuum thermal dehydration
  • Organic cationic templates, quaternary alkylammonium, structure-directing, space-filling, charge-balancing, discovery of new structures
slide3

Corner sharing SiO4/AlO4 tetrahedra

Cation binding site in six ring resembles crown ether-cation complex

Six ring shorthand notation

Mq+

ZEOLITE BUILDING UNITS

SHORTHAND NOTATION

building block approach to zeolite synthesis structures and properties
BUILDING-BLOCK APPROACH TO ZEOLITE SYNTHESIS, STRUCTURES AND PROPERTIES
  • Primary tetrahedral units, AlO2-, SiO2, PO2+ and so forth, combined to give open-framework and framework charge, balanced by extraframework cations
  • Existence of primary and secondary units in a synthesis mixture including:
  • 4R, 6R, 8R, D4R, D6R, 5-1, cubooctahedron
zeolite post modification for controlling properties of zeolites
ZEOLITE POST MODIFICATION FOR CONTROLLING PROPERTIES OF ZEOLITES
  • Tailoring channel, cage, window dimensions, adsorbents, gas separation, purification
  • Tuning Brnsted acidity, hydrocarbon cracking
  • Ion exchange capacity, Lewis acid-base character, water softening, detergents
  • Size-shape selective catalysis, separations, sensing -reactant, product, transition state selectivity
zeolite post modification for controlling properties of zeolites9
ZEOLITE POST MODIFICATION FOR CONTROLLING PROPERTIES OF ZEOLITES
  • Host-guest inclusion, atoms, ions, molecules, radicals, organometallics, coordination compounds, clusters, polymers (conducting, insulating), nanoreaction chambers
  • Advanced zeolite devices, electronic, optical, magnetic applications
  • Entry to nanoscale materials, size tunable properties, QSEs
alkylation of toluene by methanol shape selective catalytic production of p xylene
ALKYLATION OF TOLUENE BY METHANOL - SHAPE SELECTIVE CATALYTIC PRODUCTION OF p-XYLENE

Used for manufacture of terephthalic acid for production of polyester fibers

Snug fit can diffuse through channels

slide14

Shape slective dehydration of normal and iso-butanols to butenes over calcium ion exchanged zeolite A and zeolite Y

slide16
SIMPLIFIED NOTATION FOR ZEOLITE ION EXCHANGE, BRNSTED ACID SITE FORMATION AND DEALUMINATION TO HIGH SILICA ZEOLITES
slide18

The changing face of zeolite science and technology - pore and channel dimensions way beyond 1 nm - periodic table of compositions

architectural control template directed transformation of building blocks to open framework solids

Mq+ links building blocks via S binding and structure directed by Me4N+ template

Ge4S104- adamantanoid building block

ARCHITECTURAL CONTROL - TEMPLATE DIRECTED TRANSFORMATION OF BUILDING BLOCKS TO OPEN FRAMEWORK SOLIDS
learning from nature templating inorganics with single molecules and supramolecular assemblies
LEARNING FROM NATURE - TEMPLATING INORGANICS WITH SINGLE MOLECULES AND SUPRAMOLECULAR ASSEMBLIES