Preparative Methods in Inorganic Solid State Chemistry Lecture series given at the Department of Inorganic Chemistry at University of Bonn, Germany (winter term 2004/05)
R. Glaum Institut für Anorganische Chemie Rheinische Friedrich-Wilhelms-Universität, Bonn (Germany) http://anorg.chemie.uni-bonn.de/akglhome email:
[email protected]
Contents 1. Basic ideas and problems about solid state reactions 2. Phase diagrams – Reading and understanding 3. Crystal Growth from a melt 4. Crystal Growth from a flux 5. Hydrothermal/solvothermal syntheses 6. Electrochemical Syntheses 7. Chemical Vapour Transport / Chemical Vapour Deposition 8. Purification of Solids 9. Commercial processes http://za0510pc5.chemie.uni-bonn.de/akglhome
Reactivity of Solids I. dx x = (k' · t) –1/2 = k · x –1 dt parabolic growth Interface MgO / MgAl2O4: 2Al3+ – 3Mg2+ + 4MgOs = MgAl2O4,s
Interface MgAl2O4,s / Al2O3,s: 3Mg2+ – 2Al3+ + 4Al2O3,s = 3 MgAl2O4,s
Overall reaction: MgOs + Al2O3,s = MgAl2O4,s interdiffusion layer, thickness x A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Spinel MgIIAlIII2O4 cubic, a = 8,081 Å; building units: [MgIIO4] and [AlIIIO6]
O2–
Al/Cr3+
Mg2+
chromophor [CrO6] http://anorganik.chemie.uni-bonn.de/akglhome
M. C. Escher: Fishes to Birds
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1999.
Reactivity of Solids II. dx = k · x –1 dt
x = (k' · t) –1/2
x2 = k'' · t parabolic growth Wagner mechanism Interface NiO / NiAl2O4: 2Al3+ – 3Ni2+ + 4NiOs = NiAl2O4,s
Interface NiAl2O4,s / Al2O3,s: 3Ni2+ – 2Al3+ + 4Al2O3,s = 3 NiAl2O4,s
formation of NiAl2O4,s
Overall reaction: NiOs + Al2O3,s = NiAl2O4,s
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Reactivity of Solids III. Problems: high activation temperature required for migration (diffusion) of atoms (ions) in a solid low thermal stability of some reaction products
Solutions: application of high temperatures („shake and bake“; „heat and beat“; brute force methods) providing large surface areas and short diffusion paths for a solid state reaction to happen use of reactive precursor materials Solid state reactions via more mobile phases (liquid or gas phase: reactions in melts, hydrothermal synthesis, CVT) A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
An Example: Synthesis of Na3N Problem:
3Nal + 1/2N2,g ≠ Na3Ns very high activation temperature for the educts low thermal stability of the reaction product (Tdecomp ≤ 360°C)
Solution: Intimidly mixed atoms have to be reacted! Co-condensation of Na- and N-atoms Na3N: anti-ReO3 structure type T = 4K, followed by slow heating
M. Jansen, Angew. Chem. 2002, 114, 3897.
Gibbs Phase Triangles I.
Gibbs phase triangle for system Ti / P / O
http://za0510pc5.chemie.uni-bonn.de/akglhome
Gibbs Phase Triangles II.
Ternary phase diagrams A / B / C showing different homogeineity regions
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Gibbs Phase Triangles II. Co II : Co, Co3(PO4)2, Co2P Co IV: Co2P, Co2P2O7, CoP
A B C D E F G H I J K
III V I
II
IV
VI
CoO Co3(PO4)2 Co2P2O7 Co2P4O12 CoP4O11 P4O10 P4O6 Co2P CoP CoP2 CoP3
Gibbs phase triangle for system Co / P / O (T = 800°C)
A. Schmidt, Dissertation, JLU Gießen, 2002. M. Blum, geplante Dissertation, Uni Bonn.
Oxygen Coexistence Pressure I. 1. Aufstellen der Zersetzungsgleichung :
2 / 7 Co2P2O7,s = 4 / 7 CoPs + O2,g 2. Thermodynamik :
?
? ∆RHT = (4/7∆BHT(CoPs) + ∆BHT(O2,g)) - 2/7 ∆BHT(Co2P2O7,s)
Van`t Hoff :
∆ RG ln K = − RT ∆ R H ∆ RS ln K = − + RT R M. Blum, geplante Dissertation, Uni Bonn.
Oxygen Coexistence Pressure II. CoP und Co2P2O7 sind Feststoffe, also ist Kp = p(O2) Somit folgt aus :
∆ H ∆ S R T R T log(K ) = − + P 4.567 ⋅ T 4.567
∆ R H1053 − 29.028 = 4.567
und log (p(O2))= -29.028 • 1/T + 7.614
und
∆ R S1053 7,614 = 4.567
∆ R H1053 = 132,6kcal / mol ∆ R S1053 = 34,77cal / mol ⋅ K M. Blum, geplante Dissertation, Uni Bonn.
Oxygen Coexistence Pressure IIIa.
Messprinzip M. Blum, geplante Dissertation, Uni Bonn.
Oxygen Coexistence Pressure IIIb. Vorgeschaltete Messzelle Ar mit 1000ppm H2
H2/H2O
O2 I
T
U
H2/H2O
O2
Nachgeschaltete Messzelle
p(O2)=f(T)
H2/H2O
Messprinzip
I
T
U
M. Blum, geplante Dissertation, Uni Bonn.
Oxygen Coexistence Pressure IV. Trägergas : Argon mit 1000ppm Wasserstoff 1. Messzelle
Reaktor mit Probe 2. Messzelle
Befeuchtung (opt.)
Flußkontrolle ( 5l / h )
Messapparatur K.Teske, H. Ullmann, N. Trofimenko, J. Thermal Anal., 49 ( 1997 ) S.1211-1220
Oxygen Coexistence Pressure V. -16
-16
Beispiel : CoIV (Co2P, Co2P2O7, CoP)
log(p(O2)) (p(O2) in atm)
-18
log (p(O2))= 29.028 • 1/T + 7.614
-18
-20
-20
-22
-22
-24
-24
0,0008
0,0009
0,0010
0,0011
1/T [1/K] Co4blm1; Auswertung mit I
04. 02. 01
M. Blum, geplante Dissertation, Uni Bonn.
Phase Diagrams I.
incongruent melting of AB and various solid solutions A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Phase Diagram MgO – Al2O3
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Crystal Growth Techniques I. pulling direction
O2 + powder (e.g.: Al2(SO4)3 + Cr2(SO4)3) O 2 + H2
growing crystal
flame droplets
melt crucible
growing crystal crystal support
heater coil
Czochralski
Verneuil A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
ca. 250 cm
Verneuil‘s Technique
powder particel melt in the flame of an H2/O2 burner and crystallize on a crystal seedling; ruby and saphire are grown on an industrial scale applying Verneuil‘s technique W. J. Moore, Der feste Zustand, Vieweg, 1977.
Synthetische Kristalle
Synthetische Kristalle besitzen die gleiche chemische Zusammensetzung wie natürlich gewachsene. W. Schumann, „Edle Steine“, BLV Verlagsges. 1993.
Crystal Growth Techniques II. Stockbarker
Bridgman
zone melting purification and crystallisation of metals A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Flux Growth Techniques I. Reasons for application of the technique: 1) Desired material does not melt or has very high m.p. 2) Lowering of crystallization temperature 3) Improvement of crystal quality 4) Avoiding non-stoichiometry
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Flux Growth Techniques II. Choice of a flux: 1) High solubility for desired compound 2) High temperature coefficient of solubility 3) No miscibility with the compound to be crystallized 4) Inertness towards dissolved material and crucible
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Flux Growth Techniques III. Selected Examples - Oxides
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Flux Growth Techniques IV. Means of achieving crystallization from fluxed melts: A,B,C: slow cooling
Ostwald-Miers-Region
AD: evaporation of solvent EF: temperature gradient (transport)
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Flux Growth Techniques V. Temperature profile (pendulum) for seed reduction:
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Flux Growth Techniques VI. Modified flux growth
cfg. zone melting
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Flux Growth Techniques VII. elements, borides, carbides, pnictides from metallic fluxes
K.-Th. Wilke, J. Bohm, Kristallzüchtung, DVW 1988.
Hydrothermal Synthesis I. p, T diagram of water
temperature
liquid phase two phase
gas phase
critical point
density volume
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Hydrothermal Synthesis II. p, T diagram of water constant volume various percentages % of filling of an autoclave
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Hydrothermal Synthesis III. Solubilities under hydrothermal conditions 1a) 1b) 2a) 2b) 3) 4a) 4b) 5a) 5b) 6)
SiO2 – NaOH 450°C SiO2 – Na2CO3 450°C Al2O3 – NaOH 430°C Al2O3 – Na2CO3 430°C LiGaO2 – NaOH 400°C ZnO – NaOH 360°C ZnO – KOH 360°C ZnS – KOH 450°C ZnS – KOH 360°C KTa0.65Nb0.35O3 – KOH 650°C
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Hydrothermal Synthesis IV.
Steel autoclaves A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Hydrothermal Synthesis V. Solubilitiy of SiO2 in water (left) and NaOH (right) 1000 atm
solubility
750 atm
500 atm
250 atm temperature
0,5n NaOH (80% filling) A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Hydrothermal Synthesis VI.
B. R. Pamplin, Crystal Growth, Pergamon Press, 1975.
α - β Transition for Quartz Structural relationship P 62 2 2
t2
P 32 2 1
α-SiO2 ↔ β-SiO2, TT = 573°C (2nd order) H. Bärnighausen, Commun. Math. Chem. 1984, 9, 139.
Chemical Vapour Transport I. Chemical Vapour Transport: Migration of an otherwise immobile solid in a chemical potential gradient via a mobile phase (gas or liquid) Migration in a temperature gradient
transport agent
T(source)
Fe2O3,s
Cl2,g T(sink)
isothermal transport; short distance transport; mineralisation effects; hydrothermal syntheses http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport II. Chemical Transport
Physical Transport (Destillation, Sublimation)
needs a transport agent (but: autotransport)
without transport agent
migration from hot to cold (T2 6 T1) as well as from cold to hot (T1 6 T2) possible
direction always from hot to cold (T2 6 T1)
Applications: van Arkel / de Boer - Method purification of solids halogen lamps crystal growth mineral formation / Geology
Applications: purification of solids and liquids freeze drying
http://za0510pc5.chemie.uni-bonn.de/akglhome
Natural Hematite Fe2O3
http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport III. Questions: Which solids can be “transported”? Optimum experimental conditions (TA; T)? Speed of the migration (deposition); migration rate?
transport agent Fe2O3,s
Cl2,g FeCl3,g; O2,g
transporting species Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g
“transport reaction” http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport IV. Thermodynamics Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g
“transport reaction”
The migration direction is determined by the sign of the reaction enthalpy of the transport reaction: endothermic, ∆RHT > 0 Y T2 6 T1 (Def.: T1 < T2) exothermic, ∆RHT < 0 Y T1 6 T2 Examples: Oxides / chlorine Chlorides, bromides / Al2X6 Si (Ti, Fe and other metals) / iodine
endotheric exothermic
Estimation of the sign of the reaction enthalpy by consideration of bond energies of educts and products http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport V. Thermodynamics Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g
“transport reaction” “transport equilibrium”
P 2 ( FeCl3 ) ⋅ P 3/ 2 (O2 ) KP = P 3 (Cl2 )
(favorable: KP . 1; ∆RG . 0)
∆ R GT = ∆ R H T − T ⋅ ∆ R S T
Gibbs-Helmholtz-equation (selection of T)
∆ R HT ∆ R ST log K P (T ) = − + 4,567 ⋅ T 4,567
van t’Hoff-equation
http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport VI. Experimental setting and definitions ampoule dimensions: l .11cm; q . 2,0 cm2; V . 22 cm3 V(source) : V(sink) . 2 : 1 V(sink)
T(source)
SBK ABK V(source)
T(sink)
Diffusion length s: 8 - 10 cm http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport VII. Calculation of partial pressures for CVT of Fe2O3,s using chlorine: P(Cl2)T1, T2; P(FeCl3)T1, T2; P(O2)T1, T2; ΣPT1, T2 (8 unknown) Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g P 2 ( FeCl3 ) ⋅ P 3/ 2 (O2 ) KP = P 3 (Cl2 )
P( FeCl3 ) =
4 3
P(O2 )
(2 Gl.) (2 Gl.)
n°(Cl2) = [(VT1/R@T1)(P(Cl2)T1 + 3/2 P(FeCl3)T1] + [(VT2/R@T2)(P(Cl2)T2 + 3/2 P(FeCl3)T2]
Σ PT1, T2 = P(Cl2)T1, T2 + P(FeCl3)T1, T2 + P(O2)T1, T2
(2 Gl.)
Σ PT1 = Σ PT2 http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport VIII. Partial pressure calculation for CVT of Fe2O3,s using chlorine: P(Cl2)T1, T2; P(FeCl3)T1, T2; P(O2)T1, T2; ΣPT1, T2 (8 unknown pressures) Exp. conditions:
Fe2O3,s -196,8 20,9
+
V = 22cm3; V(source) : V(sink) = 2 : 1 P°(Cl2) = 1 atm bei 298 K; n° = 0,982 mmol 3 Cl2,g 3 x 0,0 3 x 53,3
=
2 FeCl3,g 2 x -60,6 2 x 82,2
+
3/2 O2,g 3/2 x 0,0 3/2 x 49,0
∆RH298 = 75,6 [kcal / mol] ∆RS298 = 57,1 [cal / mol@K] http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport IX. Partial pressures as a function of temperature: Partial pressures as a function of temperature: 5.000 4.000 3.000 2.000 1.000 0 Quelle T(source) P(gesamt) P(Cl2,g) P P(Cl2) total
Senke T(sink) P(FeCl3,g) P(FeCl3)
P(O2)
P(O2,g)
http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport X. Prerequisit for the application of the diffusion model: Diffusion between source and sink is the rate determining step of the whole migration/deposition process migration / deposition: 1.) Reaction of ABK with transport agent (mechanism) 2.) evaporation of volatile species (1. phase transfer reaction) 3.) “migration” from source to sink 4.) seed formation 5.) Crystal growth (2. phase transfer reaction)
http://za0510pc5.chemie.uni-bonn.de/akglhome
Chemical Vapour Transport XI. Transport formula derived by Harald Schäfer
i ∆ PC T 0,8 ⋅ q n A = ⋅ ⋅ ⋅ D0 ⋅ 1,8 ⋅ 10 − 3 j ΣP s nA i, j ∆Pc ΣP T q s D0
[mol ]
Mole transported solid stoichiometric coefficients partial pressure difference [atm] total pressure[atm] average temperature of diffusion path [K] cross section of diffusion path [cm2] length of diffusion path [cm] mean diffusion coefficient; 0,1 [cm2@sec-1] http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Metals I. Purification of Zirconium following van Arkel / de Boer: Zrs + 4 Ig = ZrI4,g;
280
1450°C
(similarly: Ni, Cu, Fe, Cr, Si, Ti, Hf, Th, V, Nb, Ta, U) Mos + 5/2 Cl2,g (5 Clg) = MoCl5,g;
400
Ws + 3 Cl2,g (6 Clg) = WCl6,g; 400 (thermal stability of halogenide)
1400°C 1400°C
Purification of Nickel using the Mond-process: Nis + 4 COg = Ni(CO)4,g;
80
200°C
(vgl. H. Schäfer, Chemische Transportreaktionen, Verlag Chemie (1962)) http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Metals II. Transport of Fe and Ni using halogens (exothermic): e. g.: Ms + 2 Clg = MCl2,g;
800
1000°C
Transport of Fe and Ni using hydrogen halides (endothermic): e. g.: Ms + 2 HClg = MCl2,g + 2 H2,g; 1000 800°C (vgl. H. Schäfer et al., Z. anorg. allg. Chemie 286 (1956) 42.)
Transport of noble metals: thermal instability of halides, e. g.: Rhs + 3/2 Cl2,g = RhCl3,g(s) (Y no transport) increased volatility of halides by gas complex formation, e. g.: Rhs + 3/2 Cl2,g + Al2Cl6,g = RhAl2Cl9,g; 600 800°C (vgl. H. Schäfer et al., Z. anorg. allg. Chemie 414 (1975) 137.)
http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Oxides I. Chlorine as transport agent: Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g; TiO2,s + 2 Cl2,g = TiCl4,g + 2 O2,g;
1000
900
MoO3,s + Cl2,g = MoO2Cl2,g + 1/2 O2,g; Nb2O5,s + 3 Cl2,g = 2 NbOCl3,g + 3/2 O2,g;
900°C
800°C 900 1000
800°C 900°C
Problem: a) frequently unfavourabel equilibria; b) transport of lower (stronly reducing oxides) is impossible Y Oxidation Solution: avoiding “free” oxygen; using non-oxidising transport agents (HCl, TeCl4, TaCl5, PI3) http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Oxides II. Non-oxidising transport agents: Fe2O3,s + 6 HClg = 2 FeCl3,g + 3 H2Og;
900
Ti3O5,s + 12 HClg = 3 TiCl4,g + 5 H2Og + H2,g; MoO3,s + TeCl4,g = MoO2Cl2,g + TeOCl2,g; Ta2O5,s + 3 TaCl5,g = 5 TaOCl3,g; 3 TiO2,s + 4 PI3,g = 3 TiI4,g + P4O6,g;
800°C 900
900
800°C 800°C
1000
900°C
900
800°C
Problems: occuring of solid (condensed) binary (halides) and ternary (tantalates; phosphates) phases http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Complex Oxides
I.
Transport behaviour similar to binary components: CoNb2O6,s + 5/2 Cl 2,g = CoCl2,g + NbOCl3,g + 5/2 O2,g NiTiO3,s + 3 Cl2,g = NiCl2,g + TiCl4,g + 3/2 O2,g (Co1-xZnx)Os + Cl2,g = (1-x) CoCl2,g + x ZnCl 2,g + 1/2 O2,g Stabilisation of binary componenten by formation of the ternary phase leeds to lower solubility in the gas phase of the ternary phase in comparison to the binary phases. lower solubility generally means lower solubility difference (lower migration rate) http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Complex Oxides
II.
Chemical Vapour Transport of anhydrous sulfates: ZnSO4,s + Cl2,g = ZnCl2,g + SO2,g + 1/2 O2,g Fe2(SO4)3,s + 3 Cl2,g = 2 FeCl3,g + 3 SO3,g + 3/2 O2,g Fe2(SO4)3,s + 3 Cl2,g = 2 FeCl3,g + 3 SO2,g + 3 O2,g FeSO4,s + 2 HClg = FeCl3,g + SO2,g + H2Og + O2,g NiSO4,s NiSO4,s
(formation of Fe2O3,s) + PbCl2,g = PbSO4,s + 2 NiOs + SO2,g + Cl2,g + Cl2,g = NiCl2,g + SO3,g + 1/2 O2,g
Al2(SO4)3,s + 3 SOCl2,g = 2 AlCl3,g + 6 SO2,g 2 VO(SO4)s + 3 Cl2,g = 2 VOCl3,g + 2 SO3,g + O2,g http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Halides
I.
Caveat: migration in a temperature gradient frequently must be regarded as distillation or sublimation! Transport via higher halogenides (TR accompanied by oxidation): 800 700°C CrCl3,s + 1/2 Cl2,g = CrCl4,g; MoBr2,s + HgBr2,g = MoBr4,g; 1000 900°C MoBr3,s + MoBr5,g = 2 MoBr4,g; 475 250°C Transport via formation of gaseous complexes using AlCl3, AlI3, FeCl3 as complexing agent: 2 AlCl3,g = Al2Cl6,g ∆DimH298 = -30,1 [kcal / mol];
∆DimS298 = -36,9 [cal / mol@K]
(vgl. H. Schäfer, Z. anorg. allg. Chemie 414 (1975) 137.) http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Halides
II.
Dissoziation behaviour of Al2Cl6,g 1.0 0.9
AlCl3,g
0.8 0.7 0.6 0.5 0.4 0.3
Al 2Cl6,g
0.2 0.1 0.0 400
600
800
1000
1200
1400
1600
temperature [K]
(compare also dimerisation of CoCl2,g and other halides) http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Halides
III.
Compositions of gaseous complexes: MCl · AlCl3; n MCl · n AlCl3; MCl2 · AlCl 3; MCl2 · 2 AlCl3; MCl3 · AlCl3; MCl3 · 3 AlCl3; MCl4 · 2 AlCl3; MCl5 · AlCl 3;
(vgl. H. Schäfer, Angew. Chemie 88 (1976) 775.) http://za0510pc5.chemie.uni-bonn.de/akglhome
Transport of Halides
IV.
Examples (synthesis of crystaline, anhydrous halogenides): 2 CrCl3,s + 3 Al2Cl6,g = 2 CrAl3Cl12,g 450 CrCl2,s + Al2Cl6,g = CrAl2Cl8,g; CoBr2,s + Al2Br6,g = CoAl2Br8,g; 400
350°C 300°C
( H. Schäfer, Angew. Chemie 88 (1976) 775.)
Pt (excess) + Br2,s + Al2Br6,g Y PtBr3,g; 400
350°C
But: Pd (excess) + I2,s + Al2I6,g Y Pd2Als + I2,g; T: 350 - 600°C 600°C Transport of Pd2Als: 375 ( H. Schäfer et al., J. Less-Common Met. 61 (1978) 47.) http://za0510pc5.chemie.uni-bonn.de/akglhome
Zeolithe M2/zO · Al2O3 · x SiO2 · y H2O
Zeolithe M2/zO · Al2O3 · x SiO2 · y H2O
Zeolithe M2/zO · Al2O3 · x SiO2 · y H2O
[TO4]-Gruppen als Bausteine
Linde X/Y, Faujasit
4
Sodalith
Linde A
Ein molekularer Baukasten
Ein molekularer Baukasten
Löcher mit SiO2 drumherum
Sodalith
Linde A
Linde X/Y, Faujasit
Zeolithe besitzen Hohlräume, in die Moleküle oder Ionen eingelagert werden können.
Synthese von Zeolithen SiO2 haltige Verbindungen z.B. Wassergläser, Kieselsole
Al2O3 haltige Verbindungen z.B. Aluminiumhydoxide, Aluminate, Kaoline
+ Natronlauge, Temperatur > 50°C, hydrothermale Reaktionsbedingungen
Zeolith
Anwendungen von Zeolithen Eigenschaft
Anwendung
Adsorption
Isolierglas Kühlmittel
Dynamische Adsorption
Trocknung und Reinigung von Erdgas, Spaltgas; Luftzerlegung
Trenneigenschaften
Alkane / Isoalkane Trennung,
Ionenaustausch
Waschmittel, Abwasserreinigung
Katalyse
Fließbettcracken, Hydrocracken, Methanolumwandlung
