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HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES PowerPoint Presentation
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HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES

HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES

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HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES

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  1. 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)

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. SHAPE SELECTIVE CATALYSIS - REACTANT, PRODUCT, TRANSITION STATE SELECTIVITY

  8. 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

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

  10. DIAMOND LATTICE OF 1.3 nm SPHERICAL SUPERCAGES IN ZEOLITE Y

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

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

  13. LAYER-BY-LAYER GROWTH OF ZEOLITE THIN FILMS FOR PERMSELECTIVE MEMBRANES

  14. ORGANICS ORGANIZING INORGANICS ABIOGENIC

  15. 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

  16. LEARNING FROM NATURE - TEMPLATING INORGANICS WITH SINGLE MOLECULES AND SUPRAMOLECULAR ASSEMBLIES