CHE499 Spring 2006CHE499 Spring 2006

Zeolites

TOPICS:TOPICS:ManufactureStructure ChemistryCharacterizationApplications

ZeoliteZeolite ChemistryChemistry

Zeolites are sodium alumino silicate Al2O3 + SiO2

or, Na2O.xAl2O3.ySiO2.

They can include other chemical components and metallic ions.Pore Diameter: 2-10 Å.

History of History of ZeolitesZeolites

Discovered in 1756 by Cronstedt, a Swedish mineralogistNamed from Greek-boiling stone' (zein -boiling, lithos - stone)International Zeolite Association – 1967– Richard M. Barrer

ManufactureManufacture

ManufacturingManufacturingSyntheticNatural

Jurong'sJurong's Lube Lube BaseoilBaseoil PlantPlant(Zeolite X)

ManufacturingManufacturing

Mobil- 42 Synthetic Zeolites (over 1/3 of all)Thermofor Catalytic Cracking (TCC) ZSM-5, currently in over 100 reactors

StructureStructure

ZeolitesZeolites: : FaujasiteFaujasite

Naturally Occurring Naturally Occurring ZeoliteZeolite

IZA DatabaseIZA Database

http://www.iza-structure.org/databases/

http://crystals.ethz.ch/IZA-SC/3D-images/FWviewer.php?cifname=FAU&FTC=FAU

IZA IZA ZeoliteZeolite DatabaseDatabase

FaujasiteFaujasite

Inclusion of Inclusion of FluoresceinFluorescein

Inclusion of Inclusion of AlkaneAlkane MoleculeMolecule

ZSM 5ZSM 5

Various Crystalline StructuresVarious Crystalline Structures

MCM22, ZSM5MCM22, ZSM5

ChemistryChemistry

ZeolitesZeolites

Zeolites are sodium alumino silicatecompounds with the general formula

Na2O.xAl2O3.ySiO2.

They are a large family of compounds which can have many different ratios of the base constituents and can include other chemical components.

ReactionsReactionsHydrated alumina is reacted with caustic soda

(NaOH) to form sodium aluminate as per the following equation. Sodium aluminate(chemically NaAl(OH)4) is made by reacting hydrated alumina (Al(OH)3) with caustic soda (NaOH) according to the following reaction:

Al(OH)3 + NaOH -> NaAl(OH)4 + H2O

The reaction produces a sodium aluminatesolution. This solution is then reacted with sodium silicate (NaSiO4) to form the zeolite.

Tetrahedral StructuresTetrahedral Structures

CharacterizationCharacterization

Transmission Electron Microscopy Scanning Electron MicroscopySolid State NMR

Simulation Methods– Molecular Modeling (Surface Interactions)

Dr. Snurr at Northwestern University– Molecular Dynamics (Electrical Properties)– Ab Initio Quantum Calculation (Extra

framework)– Thermodynamic Integration

CharacteristicsCharacteristicsT-atoms; tetrahedrally bonded by oxygen– T: usually Aluminosilicates, but P,Ga,Ge,B,etc.Negatively charged (attracts + ions)Pore Diameter: 2-10 ÅSurface Area: 50-135 mm2/g (large)Stable under thermal cycling, extreme temperatures, and harsh chemical environ.Hydrophobic and Hydrophilic surfaces

ApplicationsApplications

The main uses of Zeolites are:Detergents as "builders". Detergent builders improve the effectiveness of the detergent by "softening" (removing the calcium and magnesium ions) the water. This is the major use of zeoliteand accounts for over 80% of zeoliteproduction. Catalyst supports Adsorbents Ion exchange resins Molecular sieves

Selectivity as CatalystsSelectivity as Catalysts

Products and usesProducts and uses

Odor FiltersCat Litter Gas separation

AmmoniaRemoval Petroleum refining

FertilizersWastewater Treatment

Solar Heating/Refrigerating

Environmental: Mercury Environmental: Mercury RemovalRemoval

Pacific Northwest National Laboratory

HgHg--removal on removal on SAMsSAMsencathratedencathrated in ZSM5in ZSM5