Zeolites and Zeolitic Materials Molecular sieves = highly organized matrices of tunable pore shape, size, and polarity for separation, recognition, and organization of molecules with precision of about 1 Á. detergent builders adsorbents size-shape selective catalysts supramolecular chemistry nanotechnology Chemical composition Silica Si02 Aluminosilicates MxIAlxSi2.x04. nH20 Aluminophosphates A1P04 (isoelectronic with Si204) Metallophosphates MP04 Silicoaluminophosphates M^SixAlP^ 04 Pores Channels ZSM-5[01Q] BgU [100] Zeolites and Zeolitic Materials >40 naturally occurring zeolites >139 structure types many hundreds of zeolite compounds Nomenclature www.iza-structure.org/databases Structure types - three capital letter codes (Most well known zeolite archetypes: SOD, LT A, FAU, MOR, MFI ) Four-connected frameworks Interrupted frameworks (denoted by a hyphen: -CLO, cloverite) Structure types do not depend on: chemical composition, element distribution, cell dimensions, symmetry Several zeolite compounds can belong to the same structure type: FAU - faujasite, Linde X, Y, Beryllophosphate-X, SAPO-37, Zincophosphate-X Zeolites and Zeolitic Materials Names of zeolite materials: trivial names - Alpha, Beta, Rho chemical names - Gallogermanate-A mineral names - Chabazite, Mordenite, Stilbite, Sodalite codes - A1P04-5, 8,11,..., 54, ZSM-4,18, 57,... brand names - Linde A, D, F, L, N, Q , R, T, W, X, Y university names VPI-5 (Virginia Polytechnical Institute) ULM (University Le Mans) 4 Zeolites and Zeolitic Materials Primary building units: A1(III)04, P(V)04 and Si(IV)04 tetrahedra Isoelectronic relationship (Si02); [AlSi04 ]- A1PO, Secondary (Structural) Building Units (SBU) t> 3R 4R 5R 6R ^1 > spiro-5 D4R D6R 4-1 4=1 4-2 8R \ D8R 4-4=1 R^ \ R1 / Al , /UR2 ° R1-Ai^o-| g ^ 9 O I / ^R2 \K-mi^o-|' R1 5-1 5-2 5-3 6-2 2-6-2 6E1 (C6R) Chain composite building units (a) zig-zag unbranched single chain, periodicity of two (b) sawtooth unbranched single chain, periodicity of three (c) crankshaft unbranched single chain, periodicity of four (d) natrolite branched single chain (e) double crankshaft chain, an unbranched double chain (f) narsarsukite chain, a branched double chain (g) a pentasil chain HCl doubt 4-mg (tMfíl Polyhedral composite building units [ 1 Linde A (LTA) Si/Al = 1 ZK-4 (LTA) Si/Al = 2.5 ZSM-5 Si/Al = 20 - 00 Pure Si02 Si/Al = oo Pentasils ZSM-5 Zeolite Synthesis Synthesis - an empirical and heuristic process, new phases are often discovered by serendipity Aluminosilicates - high pH Ô Mixing NaAl(OH)4(aq) + Na2Si03(aq) + NaOH(aq), 25 °C, condensation-polymerization, gel formation Ô Ageing Na(H20)n+ template effect -^ Naa(A102)b(Si02)c.NaOH.H20(gel) -^ 25-175 °C Ô Hydrothermal crystallization of amorphous gel, 60-200 °C Nax(A102)x(Si02)rzH20(crystals) Ô Separation of the solid product by filtration Ô Calcination - occluded water, removed by 25-500 °C vacuum thermal dehydration -template removal - calcination in 02 at 400-900 °C removes the guest molecules from the framework without altering it - extraction (neutral templates) Zeolite Synthesis Structure of the zeolite product depends on: - Composition - Concentrations and reactant ratios - Order of mixing - Temperature - Ageing time (hours to weeks) - Crystallization time (days to weeks, kinetics of the structure-directing process is slow) -pH - Stirring/no stirring - Pressure - Seeding - Reactor material (PTFE, glass, steel) - Templates Templates: Organic cationic quaternary alkylammonium salts, alkylamines, aminoalcohols, crownethers, structure-directing, space-filling, charge-balancing Vary the template - discover new structures ! T ■ * . „ Templates Template or guest compounds A Three levels of the guest action with increasing structure-directing specificity: ■ Space-filling - the least specific, observed, for example, in the synthesis of AlP04-5,23 different, structurally unrelated compounds, could be employed, they pack in the channels of the structure thereby increasing its stability. ■ Structure-directing - a higher degree of specificity, only tetramethylammonium hydroxide is effective in the synthesis of AIPO4-2O -elongated molecules, such as linear diamines, initiate the formation of channels -nondirectional-shaped guests leads to the formation of cage-like cavities, the size of these cavities correlates with the size of freely rotating guests ■ True templating - very rare, it requires even more precise host-guest fit which results in the cessation of the free guest-molecule rotation A curiosity: aluminophosphate VPI-5 does not require any guest for its formation! 23 Templates The ratio T02/(C + N + O) is a measure of space-fillin of the framework by the guest molecules, characteristic for a specific guest and structure. Existence of primary and secondary units in a synthesis mixture 4R, 6R, 8R, D4R, D6R, 5-1, cubooctahedron Zeolite Synthesis Mechanisms (a) gel dissolution and solution mediated crystallization (SBU in solution) a % (b) "in situ" rearrangement of the gel 25 Zeolite Synthesis Mechanisms I Mechanism of structure-directing action of the TPA template X soluble silicate species I v< J»-* rf5 0 26 Crystallization Mechanism Induction Crystallization chemical evolution of the system j no further changes in the chemical composition of the solid initial gel containing nuclei gel Iransformation cr)?ta] aggregates 100-300 nm 100-300 nm emlvddetJ in an aggregates of I ft-20 aggregates of 4G-5ÍI amorphous matrix nm i, i> sUillnes nm crystallites í N « crystal Motion ľ j« propagation cr^ s t alli/ »t ion r/c/ ■p a««lonieration ♦í -:| &* T Ostwald ripening > 0 (after homogen i zati on) 10 12 14 17 lime, day crystallization mechanism of FAU-type zeolite under ambient conditions 27 Zeolites and zeolitic materials Wide range of solid state characterization methods for zeolites: diffraction, microscopy, spectroscopy, thermal, adsorption and so forth Zeolite post modification for controlling properties of zeolites Tailoring channel, cage, window dimensions: -^Cation choice (Ca exchanged for Na ) -^Larger Si/Al decreases unit cell parametrs, window size decreases number of cations, free space increases hydrophobicity -^Reaction temperature, higher T, larger pores 28 Stability Rules Löwenstein rule: never Al-O-Al Dempsey rule: Al-0-Si-O-Si-O-Al is more stable than Al-0-Si-O-Al NNN-principle Bronsted Acidity Tuning Bronsted acidity: Ion exchange for NH4+ Pyrolysis to expel NH3 Calcination to expel H20 Solid acid for the hydrocarbon cracking The larger the Si/Al ratio,the more acidic is the zeolite Na 0 Na © O. Si 0^0 ,0 0.0. Al Si /\ o o .0 0.o. Al ,0 Si /\ O o Ion Exchange 0 +NH4 0 NH4 O. .0.0.0. Si Al o^o J\ 0 -Na 0 NH4 O. © ^O. .0 Si Al Si A„ „A A 0 0 0 0 0 0 Heating H °-si-0-!i-° o^o 0A0 0 Ni' A o o -NH3 Bronsted acid H -O. © .0 0 ,0 Al Si nA A oooo Calcination 600 »C -H20 Lewis acid O. ,0. Si 0^0 Al 0A0 v A o o o 0/0> Al ,o Si /\ O o 30 Brensted Acidity Protonation of hydrocarbons 121 Size- Size-shape selective catalysis, separations, sensing Selectivity at: •Reactants •Products •Transition state hape Selectivity REACTANT ______________________________ h^c CH ^zzzzzzzzzzz^ 3V2%h2 H3C CH2-S CH, OH OH----------- CH2 CH2 CH2^CH3 OH 3\ / \* CH2 CH3 h3c, S*3?^ Q CH CH2 CH3 ^^^ ČH3 OH OH HjC gH3 CH3 OH Y/rr////////Y777X CH^ CH3 4V PRODUCT OH jrr-k <■ H3C-f V CH2-CH3 *—' OH 77777/77, H£C=OH2 F/V7777 TRANSITION STATE /77-xylene |A/VV/ / / / //^ 7 jjJJ^ OH H^CH3 H3C<^iH OH H3C- CH3 -^- * no toluene, OH no trimethyl- benzenes Separation of xylene isomers by pervaporation thru a MFI membrane 33 Zeolite Applications Odor control, adsorbents Ion exchange capacity, water softening, detergents (25wt% zeolite) Host-guest inclusion, atoms, ions, molecules, radicals, organometallics, coordination compounds, clusters, polymers (conducting, insulating) Nanoreaction chambers Advanced zeolite devices, electronic, optical, magnetic applications, nanoscale materials, size tunable properties, QSEs HRTEM ' * • 35 Aquaculture Ammonia filtration in fish hatcheries Biofilter media Agriculture Odor control Confined animal environmental control Livestock feed additives Horticulture Nurseries, Greenhouses Floriculture Vegetables/herbs Foliage Tree and shrub transplanting Turf grass soil amendment Reclamation, revegetation, landscaping Silviculture (forestry, tree plantations) Medium for hydroponie growing Household Products Household odor control Pet odor control Industrial Products Absorbents for oil and spills Gas separations Radioactive Waste Site remediation/decontamination Water Treatment Water filtration Heavy metal removal Swimming pools Wastewater Treatment Ammonia removal in municipal sludge/wastewater Heavy metal removal Septic leach fields Aluminophosphates "f Isoelectronic relationship of A1P04 to (Si02)2 +Ionic radius of Si4+ (0.26 Á) is very close to the average of the ionic radii of Al3+ (0.39 Á) and P5+ (0.17 Á) Many similarities between aluminosilicate and A1P04 molecular sieves Dense A1P04 phases are isomorphic with the structural forms of Si02: quartz, tridymite, and cristobalite Aluminosilicate framework charge balanced by extraframework cations Aluminophosphate frameworks neutral (A102~)(P02+) = A1P04 Aluminophosphates Some A1P04 structures are analogous to zeolites while other are novel and unique to this class of molecular sieves. Only even-number rings = the strict alternation of Al and P atoms Incorporation of elements such as Si, Mg, Fe, Ti, Co, Zn, Mn, Ga, Ge, Be, Li, As, and B into the tetrahedral sites of A1P04 gives a vast number of element-substituted molecular sieves (MeAPO, MeAPSO, SAPO) important heterogeneous catalysts M1+, M2+, and M3+ incorporate into the Al sites M5+ elements incorporate into the P sites This substitution introduces a negative charge on these frameworks. Si4+, Ti4+, and Ge4+ can either replace P and introduce a negative charge or a pair of these atoms can replace an Al/P pair and retain the charge neutrality. 38 Aluminophosphates Aluminophosphate Synthesis Aluminophosphates prepared by the hydrothermal synthesis Source of Al: pseudoboehmite, Al(0)(OH), Al(0/-Pr)3 Mixing with aqueous H3P04 in the equimolar ratio - low pH ! Forms an A1P04 gel, left to age One equivalent of a guest compound = template Crystallization in a reactor Separated by filtration, washed with water Calcination Other zeolite materials Oxide and non-oxide frameworks, sulfides, selenides Coordination frameworks, supramolecular zeolites The quest for larger and larger pore sizes 40 Cobalto-Aluminophosphate ACP-l (Co/AI 8.0) bcc arrangement of the double 4-ring units (D4R) Ethylenediamine molecules are located inside 8-ring channels At the centre of each D4R, there is a water molecule, 2.31 Á away from four metal sites Al(0-iPr)3, CoC03.H20, 85% H3P04, ethylene glycol, ethylenediamine, pH 8.4 Heated in a Teflon-coated steel autoclave at 180 °C for 4 d 41 Synthesis of Double 4-ring Units (D4R) *&^\ v /°"/P / \ l R1 / -Al /UR2 *R^ R^ 'R1 °- V° 0 1 Ö Sc 9 flP-o Q. q Sví O b 1 O-Äc-O 0 1MB ft-"0 l*-^ o On ŕJ PK) O CUT) b 5Sf CT2t\ci4l jft-o 42 Metallo-Organic Framework (MOF) Structures 4000 structures known (2008), 1000 new per year Metal centers • Coordiantive bonds • Coordination numbers 3-6 • Bond angles Polytopic Ligands Organic spacers Flexible - rigid Variable length 43 Polytopic Organic Linkers Polytopic N-bound Organic Linkers Cationic framework structures Evacuation of guests within the pores usually results in collapse of the host framework Molecular Complexes Extended Solids a • + oo © 1 ii-%^4, ^/i-^xVT/^ -S3 Expanded Framework A + — ar Angular Unit Linear Unit (A) It) Solvent /\ => / \ £---i TriinsttíA1^»,) f SO- v A Siii-vi-nL Square (A1«!1«} Suhciu S(iu»rt (AJlA1,l SolvcM »•^ +^S .=> Square {A^a'j} LM* A Sokwil A r -> Z7 Solvent V* \ i«. \ / A L k-^-r Pernatou f aWj) SflŕTtDI LtO' + I1Q- ŕ o Heapm tA'jA'j) -Os. . 130' + Soluni (*" >| Heuten (a'j/J Solvent Triangular Pri*« 78-M Solvent Octahedron (A^A1,) S*----Z^ Cube í a'iL'u) 1W* Solvent Cubwtabedron (A',L ,|) 46 Metallo-Organic Framework Structures 30 +- OTf i R^P-Pl-PRj RjP-Pt-PRj OTT 26R=Ei,ll=L 2TR=Pkn=2 Scheme A. Self-Assembly of Dodecahedra 20 /** CH^CJ^ acetone, rt ~I 60+ 60*OTf Et,n=t (W%j Ph,n=2 (W%) mm38*m?tt& Al Polytopic carboxylate linkers HH KHK 1 p4-benzenedicarboxylate (BDC) Y 1 ř4-azodibenzoate (ADB) VW 1,3,5-benzenetricarboxylate (BTC) m 1,3,5,7-adamantanetetracarboxylate (ATC) 48 Polytopic Carboxylate Linkers Aggregation of metal ions into M-O-C clusters form more rigid frameworks frameworks are neutral no need for counterions Molecular Complexes Extended Solids Decorated-Expanded Framework 49 MOF-5 Zn40(BDC)3.(DMF)8(C6H5Cl) •Zn(N03)2 + H2BDC in DMF/PhCl •Addition of TEA: deprotonation of H2BDC •Addition of Zn2+ • Addition of H202: formation of O2- in the cluster center Cavity diam. 18.5 Á Nature, 1999, 402, 276 a primitive cubic lattice MOF-5 MOF-5 Stable even after desolvation at 300 °C in air 1600 g 1200 | 800 I gas sorption isotherms for MOF-5 400 0 #* » ♦ ♦♦♦♦♦ ♦ i Ar N2 CCI, C6H( ♦ ♦ ♦ ♦ CHCI3 ♦ C6H12 0.2 0.4 0.6 P/P. MOF MOF MOF MOF MOF MOF MOF -2 -3 -4 -5 -6 -9 -11 8 140 14 12 2900 pore diameter 7 (á) surface area 270 (m2/g) pore volume 0.094 0.038 0.612 1.04 (cm3/g) 4 8 7 127 560 0.099 0.035 0.20 0.8 51 Interpenetration MOF-9 Interpenetration 53 Metallo-Organic Framework Structures Mwľä Mwľj * i r dl I llllíWIIMIH PiidS'^SSu !■■■ IIHIK^« Kl^Äj^^íjAÄW" ElOH vapour, RT 100 ftC 54 Basic Nets coordination coordination figtires net 3 triangle triangle SrSi2 a dt \idti 3 triangle triangle ThSi2 3 triangle triangle 63 honeycomb 3,4 triangle square Pt304 4 square square NbO 4 tetrahedron tetrahedron diamond (C) 4,4 square tetrahedron cooperite (PtS) 4 square square 44 square lattice Si nat of SrSÍ2 G octahedron octahedron primitive cubic ft cube cube body-cente red cubic «J Si rttlof"TnSÍ2 63 Honeycomb Pt304 Diamond (C) I,-------------1 i-------------1 i-------------1 41-------------11-------------U-------------1 II—(I—II—I II—II—II—I Cooperite (PtS) 44 Square lattice Primitive cubic Inorganic and Metallo-Organic Quartz 56 MIL-100 and MIL-101 MIL-101 Record Surface area 5 900 m2/g 57 Covalent Organic Frameworks (HO)2B—ŕ ^>—B(OH)2 COF-1 -H20 t? 1 ' 0 -B~° r~\ °~B 0 B—(7 VB O B-0 x=/ O-B 0 0 * /T^ P~Bs P~P /=\ - -H SV-B O O B—(v /VI-^^ O-B B-0 ^^ 0 0 B-O f=\ O-B B-0 ^^ O-B __/ \__ 0^ 0 "K VB, P 15 A P B-& M-•=/ O-B s. B-0 ^-ľ 0 ^0 q b—f Vb p b-o ^^ o-b' 0 0 X COF-1 ^V Solvents - reactants are poorly soluble (to slow down the reversible condensation) sealed pyrex tubes minimize defects by self-healing. COF-1 = microcrystalline, high yield, high structural order by XRD Solvent molecules are enclosed inside the pores, can be removed at 200 °C without collapse of the crystalline structure. surface area of 711 m2 g1 58 Covalent Organic Frameworks 3D frameworks COF-102, COF-103, COF-105, and COF-108 COF-108 - bor structure two different types of pores diameters of 15.2 and 29.6 Á. density 0.17 g cm3 surface area, m2 g1 COF102 3472 COF103 4210 CQ"-102 COF-1D5