1 / 23

HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES

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 

joshua-cruz
Download Presentation

HYDROTHERMAL SYNTHESIS AND CRYSTALLIZATION OF ZEOLITES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related