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A General Method for the Ion Exchange of Zeolites Utilizing the Volatility of Thallous Compounds as Leaving Products Karl Seff† Department of Chemistry, UniVersity of Hawaii, Honolulu, Hawaii 96822 ReceiVed: February 17, 2010; ReVised Manuscript ReceiVed: June 12, 2010
A new method of ion exchange entitled “thallous ion exchange” (TIE) is proposed without experimental confirmation. First, a zeolite or other porous solid is fully ion exchanged with Tl+ from aqueous solution and fully dehydrated. It is then exposed to the anhydrous vapor of a halide MXn where Mn+ is the incoming cation. The volatile product TlX(g) is easily removed, leaving behind, when successful, the fully cation exchanged material with no other content. During the Mn+ exchange step, the zeolite is in contact only with gases and its container. The Tl+ exchanged zeolite may also be used in solid state ion exchange to yield TlX(g). Although Tl+ is best for this, some other metal cations may be used. Although the halides offer much versatility with relative safety, oxides and organometallic compounds may be used because the Tl2O and R3Tl products are also volatile. 1. Introduction 1.1. The Range of the Method. The method of ion exchange proposed herein, “thallous ion exchange” (TIE), is applicable to all porous solids with ion exchange capacity; they may, however, need to be at least somewhat refractory. Thus it includes zeolites and mesoporous materials. It addresses zeolites as representative of the group and because it may have its greatest utility with regard to them. The method utilizes Tl+ as the leaving cation primarily because its ion exchange from aqueous solution is generally complete and many of its compounds (halides, oxides, etc.) are relatively volatile. However, a few other metal cations may be used instead. For the introduction of the incoming cation, its halides present the most versatility with relative safety, but a few oxides, many organometallic compounds, and others may find use. 1.2. The Chronic Difficulties of Ion Exchange from Solution. One or more of the following problems are usually associated with the ion exchange of zeolites from solution. Often ion exchange is incomplete. Often H+, OH-, or both, arising from the hydrolysis of the incoming cation, generally enhanced within the zeolite, accompany the incoming cation into the zeolite. Often excess molecules of the salt of the incoming cation are accepted into the zeolite (imbibition), and often impurity cations selectively concentrate in the zeolite. Also, the low solution pH that results from the hydrolysis of some cations can destroy a low silica zeolite. Finally, the cations of many elements do not have salts (nitrates for example) that dissolve simply in water to give suitable ion-exchange solutions. The problems of hydrolysis and pH cannot be avoided by using nonaqueous solvents; ion exchange from several zeolitically dry polar nonaqueous solvents has been shown to be unsuccessful.1,2 Partly because of these limitations, many fewer than half of the cations in the periodic table have ever been studied without unwanted complication as extraframework cations in zeolites. As can be seen above, water itself is involved in most of these problems. It is of course present when ion exchange is done using aqueous solutions, but it is also present when nonaqueous solutions that have not been rigorously dried are †
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used. Similarly it is present in solid state ion exchange (SSIE) unless the materials involved have been fully dehydrated; this is generally not done. 1.3. The Promise of TIE. It is expected that many or all of the chronic difficulties presented above can be avoided by using TIE. In addition, TIE should allow many heretofore inaccessible ion exchanged compositions to be prepared. Possible examples are Zn6-LTA, Be48-LSX (FAU), Fe2+-X (FAU), V3+-Y (FAU), and Cu+-MFI. All would have no content other than that shown in the formula as written, no other cations including no H+, no guest molecules including no H2O, and no anions such as OH-, O2-, or halide. Complete and stoichiometric ion exchange may readily be achieved in many instances. “Complete” is used here to mean that all of the exchangeable cations in the starting zeolite have exited the zeolite and have been replaced by the cations of a single element. “Fully” is synonymous with “complete.” Stoichiometric” is used here to mean more: that the exchange has occurred without complication such that the cations present in the product zeolite are all in the same oxidation state as introduced. 2. Thallous Ion Exchange (TIE) In TIE, a fully Tl+ exchanged zeolite is treated with a compound of the incoming metal ion. The resulting Tl+ compound is volatile and is therefore easily removed, leaving behind the pure ion exchanged zeolite. 2.1. Selection of the Thallous Ion. Tl+ has been selected for these experiments for the following six reasons. a. All of its halides, TlF, TlCl, TlBr, and TlI, are volatile at temperatures that are commonly used to dehydrate zeolites, ca. 350 to 450 °C. See Table 1. b. Tl+ exchange from aqueous solution is easy and quantitative. This has been seen in zeolites with a broad range of structures and Si/Al ratios, from LTA8 to FAU (X9 and Y10) to MFI (ZSM-5).11 These zeolites prefer Tl+ to the alkali metal cations, often Na+, that are to be exchanged out of the zeolite; the result is complete Tl+ exchange. Donald Breck noted this high selectivity for Tl+ in LTA, X, Y, and CHA.12 It remains
10.1021/jp101477k 2010 American Chemical Society Published on Web 07/15/2010
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TABLE 1: Vapor Pressures of the Thallous Halides (TlXs) at Various Temperaturesa 0.0075 Torr
0.075 Torr
b
TlF TlClc TlBrd TlIe ZnCl2f CdI2f
305(l) 296(s)
356(l) 344(s)
0.75 Torr
7.5 Torr
414(l)
509(l) 504(l) 509(l) 520(l)
419(l) 406(l)
497(l) 498(l)
a Temperatures are given in °C. The phase of each salt at each temperature is given. b Reference 3. c References 4 and 5. d References 5 and 6. e References 5 and 7. f ZnCl2 and CdI2 are the two halides, of the many given in ref 5, whose vapor pressures are closest to those of the thallous halides. From the values given for ZnCl2 and CdI2, the unavailable values for the TlXs can, without precision, be estimated. The melting points of the four Tl salts are 326, 430, 460, and 442 °C, respectively, so they are likely to be solids at all or most of the missing values in this table. CdI2 melts at 387 °C, so, like the TlXs, it also changes phase in the vapor pressure range given. It can be seen that TlX vapor pressures of ca. 0.1-1.0 Torr, entirely suitable for the mass transport of TlX from the zeolite, are readily achieved at temperatures at which zeolites are customarily dehydrated, from ca. 350 to 450 °C.
possible that Tl+ exchange into some smaller pore zeolites may be incomplete. c. Tl+ shows a negligible tendency to hydrolyze.13 In this sense, its chemistry in aqueous solution is remarkably like that of the alkali metal ions. Accordingly, the concentrations of TlOH and H+ due to hydrolysis are negligible and neither complicates the Tl+ exchange reaction. d. No imbibition of Tl+ salts from aqueous solution has been observed. That is excess Tl+ ions, together with charge balancing anions such as NO3- or OH-, do not enter the zeolite. (However, to avoid possible imbibition, Tl+ exchange has been done only with aqueous TlNO3 in these laboratories.8–11) e. Complete dehydration is easily achieved without undesirable side reactions. Tl+ does not disproportionate to other oxidation states nor does it react with the zeolite framework to give, for example, Tl(s) and O2(g). f. Finally, the thallous halides are stable at temperatures used to dehydrate zeolites. As leaving products, they do not decompose nor rearrange to deposit Tl(s) or Tl(III) halides. Other cations that also quantitatively replace Na+ have some of the problems enumerated in section 1. For example, Cd2+, whose halide salts also have moderate vapor pressures at zeolite dehydration temperatures, often brings hydroxide and/or halide ions with it into the zeolite from aqueous solution (imbibition).14 Ag+ reacts with oxide ions of the zeolite framework when vacuum dehydration is attempted,15,16 and the silver halides are neither volatile nor stable. Pb2+ exchange often shows imbibition unless the pH is kept low,17–19 and its halides, PbX2, are all somewhat less volatile than TlX.5 In specific instances some of these problems can be overcome and these and other metals may find use. 2.2. Thallous Vapor Phase Ion Exchange (TVPIE). One general advantage of TVPIE is that it naturally avoids the concentration of trace amounts of unwanted cations Cm+ from the exchange medium into the zeolite during Mn+ exchange. In contrast, when solutions of ultrapure salts, or the salts themselves in SSIE, are brought into contact with a zeolite, trace ions such as Na+ from the ion exchange salts, even if ultrapure, can selectively exchange into the zeolite. The compound of Cm+ with the anion of the Mn+ used generally either will not be volatile at the temperature of the experiment and thus cannot
reach the zeolite or (less often) will have volatilized away with residual moisture as the MXn is brought to temperature. Section 5 is a glossary of the ion exchange (IE) acronyms used in this report. 2.2.1. Thallous Volatile Halide Ion Exchange (TVHIE). A versatile method for achieving complete ion exchange while avoiding complications (section 1.2) is TVHIE. In this procedure, the zeolite sample is in contact with no liquid and no solid other than its container. Because of this, interphase ion exchange selectivity coefficients, which generally vary with (are complicating functions of) the degree of ion exchange, are not a concern. It employs the volatile MXn halides, both the salts and the more covalent molecular compounds, where Mn+ is to be exchanged into the zeolite. The use of other volatile compounds is discussed in sections 2.2.2-2.2.4. Initial TVHIE experiments are in progress. To do TVHIE, the zeolite is first fully exchanged with Tl+ from aqueous solution and fully dehydrated; vacuum dehydration at 350 °C is adequate. An inert zeolitically dry carrier gas would generally be used to bring the MXn vapor to the fully Tl+ exchanged zeolite and to carry the product TlX vapor away. By mass action, the pure anhydrous fully ion-exchanged zeolite M-Z should remain. The ion exchange reaction is a metathesis reaction.
AB + CD f AD + CB
(1)
MXn(g) + Tl-Z f M-Z + TlX(g)
(2)
Specifically
(p/nMXn(g) + Tlp-Z f Mp/n-Z + pTlX(g) is a balanced reaction) (3) • MXn(g) is the vapor of the halide of the incoming cation. • Mn+ is the incoming cation. • X is F-, Cl-, Br-, or I-. • n ) 1, 2, 3, .... • Tl-Z is the fully Tl+-exchanged, fully dehydrated zeolite. Its unit cell formula may be used in the above reaction. • M-Z is the fully dehydrated zeolite product. The reactions above assume that it has been stoichiometrically exchanged; other outcomes are possible (section 2.4.2). • TlX(g) is the thallous halide vapor that leaves the zeolite. Many MXn compounds, like the TlX salts in Table 1, have adequate vapor pressures near or below (sometimes well below) the temperatures at which the TlXs are volatile. This may be attributed to their covalent character and resulting tendency to form solids that are more molecular than ionic. A selection of these TlX halides is given in Table 2. As an example of a TVHIE reaction, anhydrous SnCl2 vapor may be brought into contact with fully dehydrated Tl+exchanged zeolite Y (FAU) to give anhydrous Sn2+-Y.
27SnCl2(g) + Tl54-Y f Sn27-Y + 54TlCl(g) per unit cell (4) The SnCl2 source would provide an adequate vapor pressure of SnCl2(g) at ca. 300 °C and the product TlCl would be sufficiently volatile to leave the zeolite sample if the latter was maintained at ca. 425 °C.
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TABLE 2: Some MXn Halides Suitably Volatile for TVHIEa cation atomic nos. 4-13 BeCl2 AlCl3
cation atomic nos. 22-26 339 121
TiCl3 VBr3 FeI2 FeCl3
cation atomic nos. 29-33 598b 456c 604d 229
CuI ZnI2 GaCl3 AsI3
cation atomic nos. 46-51 636 488 72e 187
PdCl2 CdI2 InBr3 InCl SnCl2 SbI3
cation atomic nos. 80-83 651f 498 329 370g 381 215
HgI2 PbI2 BiCl3
198 558 249
a The data presented were found in ref 5 unless otherwise indicated. At the temperature (°C) given for each salt, its vapor pressure is 7.5 Torr. At somewhat lower temperatures, which might be more experimentally convenient for some of the above, the vapor pressures would still be adequate. For each cation above, only one halide is given; some or all of its other halides may have similar vapor pressures as can be seen for the halides of Tl+ in Table 1. Only MXn compounds that are volatile, much like the thallium halides or more so, are suited to TVHIE. Only cations with valences of 3 or less have been included in this table. b Reference 20. The vapor pressure formula provided is valid from 455 to 550 °C. The temperature given above, 598 °C, is therefore an extrapolation. c Reference 20. The vapor pressure formula provided is valid from 314 to 427 °C. The temperature given above, 456 °C, is therefore an extrapolation. d Reference 20. e Reference 21. f Reference 20. The vapor pressure formula provided is valid from 680 to 857 °C. The temperature given above, 651 °C, is therefore an extrapolation. g By comparison with SnCl2 whose boiling point is similar. Esd ca. 20 °C.
M may be H. The anhydrous acids HX(g) may be used to produce zeolites in their pure acid forms. For example, using the same zeolite as above
54HX(g) + Tl54-Y f H54-Y + 54TlCl(g) per unit cell (5) The H54-Y zeolite would contain no other exchangeable cations and, of course, no anions nor guest molecules. When partial rather than complete ion exchange is desired with the simplicity offered above, it is readily achievable. Instead of Tl-Z, the TVHIE experiment can begin with Tl,L-Z where Lm+ is the cation of an element that will not participate in the TVHIE reaction (because its halide is sufficiently nonvolatile and it is sufficiently electropositive); Na+, K+, and Cs+ are such cations. For example
4CuCl(g) + Na8Tl4-LTA f Na8Cu4-LTA + 4TlCl(g) per pseudo unit cell (6) The full range of ion exchange, from slight to complete, may be achieved by adjusting the Tl+ content of the starting zeolite. The nonparticipating cation Lm+ may be chosen so that it does not compete successfully for sites that a resulting cluster might occupy. For example, the reaction sequence
Cs8Tl64-FAU + 32FeCl2(g) f Cs8Fe32-FAU + 64TlCl(g) (7) Cs8Fe32-FAU + 32H2S(g) f Cs8(Fe4(SH)44+)8H32-FAU (8) might yield eight “cubic” Fe4(SH)44+ clusters per unit cell, filling the eight sodalite cavities. Toward this end, the Cs+ ions might be large enough to comfortably occupy sites that the clusters do not prefer and thus not interfere with their formation. If this reaction sequence had begun with Tl72-Y, the nine resulting clusters would exceed the capacity of the sodalite cavities and a second kind of Fe,S,H structure would need to form. If Cs22Tl32-FAU, which has a framework composition typical of commercial zeolite Y, had been the starting zeolite, the above reactions would have yielded Fe4(SH)44+ in exactly half of the sodalite cavities.
2.2.1.1. CaVeats Regarding the Vapors of Salts. For some salts at elevated temperatures, the species in the vapor phase are not the same as the formal formula of the salt. As examples, when CuCl2(s) is heated, it decomposes to give a vapor of CuCl(g) (dimers or higher oligomers are possible) and Cl2(g).22 The vapor above FeCl3(s) consists of Fe2Cl6(g) and Cl2(g) with comparable equilibrium pressures23 as FeCl2(s) forms. The vapors of the aluminum(III), gallium(III), and indium(III) chlorides, bromides, and iodides are equilibrium mixtures of MX3 and M2X6.24 The vapor pressure data available for inorganic compounds, halides in this case, are incomplete and of variable reliability. Accordingly, other halides with suitable vapor pressures may be found. Reference 5 appears to be the most complete compilation, and it provides a discussion of the reliability of the vapor pressure data that it presents. 2.2.1.2. A Shortage of Low Energy Cation Sites Can Lead to Disproportionation. When the lower energy cation sites within a zeolite are filled, any remaining cations must occupy higher energy, less suitable sites. The entire zeolite might then lower its energy by cation disproportionation.25,26 If the charge of the cations is concentrated onto fewer cations, they could all occupy the lower energy sites. In this way, the distribution of site energies in a zeolite can lead to disproportionation. The reduced atoms could migrate out of the zeolite structure or remain as members of cationic clusters. Disproportionation cannot occur if the cations are already in their highest oxidation states. Such disproportionation and cluster formation have been seen in the structures of the fully indium exchanged zeolites LTA,25 X (FAU),26 and Y (FAU, awaiting publication). For example, if Cu+-Y is prepared using a FAU sample with 32 or fewer Al3+ ions per unit cell in its framework, it should have 0 < n e 32 Cu+ ions, all which can be expected to find suitable three-coordination at site I′ or site II, which have similar energies. Whichever of these two sites they select, these Cu+ ions would be equivalent except for the disorder in the Al3+ positions. If 32 < n e 64, Cu+ ions may be expected to occupy both positions. If n > 64, the excess (n - 64) Cu+ ions must occupy less suitable sites and may correct this difficulty by disproportionating to form Cu2+ and Cu0; the Cu atoms might leave the zeolite. If they do not, they may be incorporated into cationic clusters if the zeolite can provide suitable coordination for them, in a cavity for example. The cation site energy distribution is less likely to lead to disproportionation in high silica zeolites where the cation sites
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are all of similar energy. Also, local charge balance is better achieved with cations of lower charge in these zeolites. Independent of the above, disproportionation may also occur as a result of heating. Indeed, it may be possible to raise the oxidation states of all nonframework cations within a zeolite to their maximum value in this way. 2.2.1.3. Experimental Considerations. The experimental apparatus for performing TVHIE will depend on the MXn used, its physical state, its melting point if it is a solid, and the temperature at which its vapor pressure is high enough for effective mass transport. The MXn and the zeolite may need to be maintained at two different temperatures during the experiment. Because the MXn, the zeolite sample, and the apparatus that contains them should all be dry, some or all of the above will need to be baked out, preferably in situ. If a carrier gas is used, it should be zeolitically dry. Because the product TlX(g) is highly toxic (LD50 for TlCl ) 24 mg/kg), as the excess MXn(g) might also be, provision for their safe condensation and collection must be made. If imbibition is to be minimized, the MXn(g) source could be removed (for example by cooling) at the end of the exchange experiment while the zeolite sample remains at high temperature. Thus any excess MXn might be baked out. If imbibition is to be maximized, to prepare intrazeolitic nanoclusters for example, the M-Z zeolite and the MXn(g) source could be slowly cooled together, perhaps with a small temperature difference between them so that MXn does not condense onto the zeolite. A general discussion of experimental considerations important to zeolite chemistry is available.27 2.2.2. Thallous Volatile Oxide Ion Exchange. The vapor pressure of Tl2O is about 7.6 Torr at 627 °C.28 Its vapor pressure should therefore be high enough at ca. 500 °C to flow readily out of the zeolite as a gas. This allows the above discussion of TVHIE to be extended from halides to oxides. For example
M2O3(g) + Tl-Z f M-Z + Tl2O(g)
(9)
(p/6M2O3(g) + Tlp-Z f Mp/3-Z + p/2Tl2O(g) is a balanced reaction) (10) Metal oxides, however, are generally insufficiently volatile for this reaction to occur. As2O3 and Sb2O3 are two semimetal oxides that can be used; their vapor pressures are 7.5 Torr at 236 and 610 °C, respectively.5 However, because the introduction of As3+ and Sb3+ as their halides has already been presented (Table 2), this observation does not extend the number of cations that may be introduced into a zeolite beyond those possible by TVHIE. Also, some metal oxides, like halides (section 2.2.1.1), decompose upon heating. For example, the vapor above Tl2O3(s) consists entirely of Tl2O(g) and O2(g).28 As with halides, additional oxides with adequate vapor pressures may be identified. 2.2.3. Thallous Volatile Nitrate Ion Exchange. TlNO3 boils (with decomposition) at 450 °C.29 Thus its vapor pressure will be high enough at temperatures well below 450 °C for it to be a suitable leaving vapor for ion exchange. However, the nitrates of other metals are generally not very volatile and they usually decompose well below their boiling points, so few examples of stable nitrates of potential incoming cations can be found. Also, there is a danger that the zeolite will catalyze an explosive event. 2.2.4. Thallous Volatile Organometallic Ion Exchange. There are many volatile organometallic compounds such as diethyltellurium or dimethylzinc that could be used to give
trimethylthallium as the leaving vapor. These ion exchange reactions could occur at moderate temperatures, perhaps even below ambient. However, there is much opportunity for competing reactions and even explosion, possibly catalyzed by the zeolite. These compounds as a group are very highly toxic and their relative volatility at ambient conditions adds to the danger. 2.3. Thallous Solid State Ion Exchange (TSSIE). A simple mixing of Tl-Z and MXn followed by heating would also exploit the volatility of the leaving TlX vapor. The MXn used would generally need to be less volatile than its corresponding TlX; this criterion is easily satisfied. Because a lack of volatility in the halide of the cation to be introduced is not a concern, many more cations than are listed in Table 2 may be introduced into zeolites by TSSIE. V2+, Cr2+, Ni2+, Mo3+, Pd2+, Pt2+, and U3+ are among them. Metal oxides may also be used. A metal oxide less volatile than Tl2O (nearly all are) can be mixed with Tl-Z and heated under vacuum. The Tl2O(g) product would volatilize away. Some cations that might be introduced by this method are Co2+, Ga2+, Ge3+, Rh3+, Pd2+, Ir3+, and Pt2+. As can be seen, TSSIE would allow a large new group of cations to be introduced into zeolites. TSSIE suffers some of the weaknesses of all SSIE procedures. The zeolite product would be more likely to show imbibition, and unwanted impurity cations might selectively enter the zeolite. Both of these concerns could be mitigated by using only stoichiometric amounts of highly purified halide or oxide. For best results, it will often be necessary to dehydrate the two reagents independently beforehand. 2.4. Anticipated Successes and Failures. 2.4.1. Successes. Essentially all of the elements in the periodic table, with the exception of those that are too nonmetallic to exist as cations within a zeolite and those in oxidation states that are so high that they would destroy the zeolite structure, may be introduced into zeolites by TIE. These ion exchanged zeolites would be fully dehydrated and would tend to show complete exchange and therefore have relatively simple compositions. The TVHIE method (section 2.2.1) should be the most versatile. The TVPIE methods (section 2.2, the broader category) should lead to the simplest, most ideal product compositions. TSSIE extends the range of cations that may be introduced into zeolites. 2.4.2. Failures. Despite the driving force of the leaving volatile halide, ion exchange may still be incomplete. In TVPIE some molecules, especially those whose cations have higher charge and smaller size, may simply be strongly sorbed and lack the mobility needed for the reaction to proceed to completion. The same is true for the incoming cations in TSSIE. These kinetic problems30 are encountered because, compared to aqueous ion exchange, the energy barriers for transition from one cationic site to another can be expected to be higher; without coordinating molecules, a far greater reduction in coordination number is required at the transition position. Imbibition may be observed: some anions may be retained together with additional Mn+ cations. When any of the above problems is encountered, it may be resolved by increasing the temperature of the zeolite unless its decomposition temperature is reached first. In some instances, the incoming cations may be incorporated into the zeolite framework. Thermodynamics, of course, governs. If ∆G is sufficiently positive, the reaction will not proceed at all. 3. Other Kinds of Vapor Phase Ion Exchange This section is not about TIE. It is included only to clarify the position of TIE within the realm of anhydrous vapor phase
Thallous Ion Exchange ion exchange reactions; many have been reported. They are not TIE reactions because the product vapor is not a volatile metal compound. For example, the vapors of an electropositive metal such as Zn31–33 or Cs can be brought to a zeolite in its H+ form, H-Z, to give the corresponding fully ion exchanged zeolite and H2(g). Vapors of Cs or Rb can be reacted with a zeolite containing the cations of a less electropositive metal such as Na.34–38 Similarly, Zn(g) can react with a Tl+-39,40 or a Cd2+containing41 zeolite. In all of these examples,31–41 although complete ion exchange was usually achieved (the cations initially in the zeolite had all been replaced), the result was something other than stoichiometric ion exchange. Sometimes extra incoming metal atoms were retained by the zeolite to give reduced cations, cationic clusters, or cationic continua. In the remaining cases, some of the product atoms remained in the zeolite as members of bimetallic cationic clusters. Stoichiometric exchange may be more reliably achieved by TIE methods. 4. Hydrogen (H+) Solid State Ion Exchange (HSSIE) Like section 3, this section is also not about TIE. It is included to acknowledge that catalytic quantities of many cations including Fe,42,43 Co,42 Cu,42 Zn,30 Ga44,45 Cd,30 and In46–51 have been successfully exchanged into zeolites using HSSIE. For this, H+ ions were first introduced into a high silica zeolite such as MFI, MOR, or BEA. The resulting H-Z was then mixed and reacted with M,30,43,49,50 MXn,42,49 or MmOp44–51 (or MmOp + H2) to give a volatile product, H2(g), HX(g), or H2O(g), respectively. As with thallous compounds in TIE, these reactions are driven toward completion by the removal of these volatile products. M or Mn+ can change oxidation state in these processes. When elemental M is oxidized, the process has been named oxidative SSIE (OSSIE);30,43,49,50 in the other half reaction, the H+ in H-Z is reduced to H2. When the cation M in MmOp is reduced, by decomposition or by the use of H2, the process has been named reductive SSIE (RSSIE);44–51 in the other half reaction, H2O and sometimes O2 is produced. Without change of oxidation state but by simple replacement using their chlorides, Fe,42 Co,42 Cu,42 and In49 have been introduced into MFI. Because low silica zeolites usually decompose upon H+ exchange, high silica zeolites must be used for HSSIE. Except for RSSIE where water is a necessary product of the reaction, the HSSIE reactions may be anhydrous. Although the problems associated with the presence of H2O (section 1.2) and HCl, and SSIE (section 2.3), may be substantial, complete and stoichiometric ion exchange may have been achieved in some cases. 5. Glossary of Ion Exchange (IE) Acronyms Used TIE TVPIE
TVHIE TSSIE SSIE HSSIE OSSIE RSSIE
thallous ion exchange, includes TVPIE and TSSIE thallous vapor phase ion exchange, includes TVHIE and TIE with volatile oxides, nitrates, and organometallic compounds thallous volatile halide ion exchange thallous SSIE solid state ion exchange hydrogen (H+) SSIE, includes OSSIE, RSSIE, and HSSIE with metal halides oxidative SSIE reductive SSIE
References and Notes (1) Ho, K.; Lee, H. S.; Leano, B. C.; Sun, T.; Seff, K. Zeolites 1995, 15, 377.
J. Phys. Chem. C, Vol. 114, No. 31, 2010 13299 (2) Bae, D.; Seff, K. Zeolites 1996, 17, 444. (3) Keneshea, F. J.; Cubicciotti, D. J. Phys. Chem. 1967, 71, 1958. (4) Cubicciotti, D. J. Phys. Chem. 1964, 68, 1528. (5) Handbook of Chemistry and Physics, 90th ed.; Lide, D. R., Ed.; CRC Press: Boca Raton, FL, 2009; p 6-72. (6) Cubicciotti, D. J. Phys. Chem. 1964, 68, 3835. (7) Cubicciotti, D. J. Phys. Chem. 1965, 69, 1410. (8) Riley, P. E.; Seff, K.; Shoemaker, D. P. J. Phys. Chem. 1972, 76, 2593. (9) Kim, Y.; Han, Y. W.; Seff, K. Zeolites 1997, 18, 325. (10) Lim, W. T.; Seo, S. M.; Wang, L.; Lu, G. Q.; Heo, N. H.; Seff, K. Microporous Mesoporous Mater. 2010, 129, 11. (11) Heo, N. H.; Kim, C. W.; Kwon, H. J.; Kim, G. H.; Kim, S. H.; Hong, S. B.; Seff, K. J. Phys. Chem. C 2009, 113, 19937. (12) Breck, D. W. Zeolite Molecular SieVes; Wiley: New York, 1974; p 529. (13) Baes, C. F., Jr.; Mesmer, R. E. The Hydrolysis of Cations; Krieger: Malabar, FL, 1986; p 328. (14) McCusker, L. B.; Seff, K. J. Am. Chem. Soc. 1978, 100, 5052. (15) Kim, Y.; Seff, K. J. Am. Chem. Soc. 1978, 100, 175. (16) Kim, S. Y.; Kim, Y.; Seff, K. J. Phys. Chem. B 2003, 107, 6938. (17) Ronay, C.; Seff, K. J. Phys. Chem. 1985, 89, 1965. (18) Yeom, Y. H.; Kim, Y.; Seff, K. J. Phys. Chem. B 1997, 101, 5314. (19) Shibata, W.; Seff, K. Zeolites 1997, 19, 87. (20) Lange’s Handbook of Chemistry, 16th ed.; Speight, J. G., Ed.; McGraw Hill: New York, 2005; p 10-29. (21) Handbook of Chemistry and Physics, 33rd ed.; Hodgman, C. D., Ed.; The Chemical Rubber Co.: Cleveland, OH, 1951; p 1937. (22) Hammer, R. R.; Gregory, N. W. J. Phys. Chem. 1964, 68, 3229. (23) Hammer, R. R.; Gregory, N. W. J. Phys. Chem. 1962, 66, 1705. (24) Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochmann, M. AdVanced Inorganic Chemistry, 6th ed.; Wiley: New York, 1999; p 180. (25) Heo, N. H.; Choi, H. C.; Jung, S. W.; Park, M.; Seff, K. J. Phys. Chem. B 1997, 101, 5531. (26) Heo, N. H.; Park, J. S.; Kim, Y. J.; Lim, W. T.; Jung, S. W.; Seff, K. J. Phys. Chem. B 2003, 107, 1120. (27) Seff, K. Comments Inorg. Chem. 2007, 28, 173. (28) Holstein, W. L. J. Phys. Chem. 1993, 97, 4224. (29) Handbook of Chemistry and Physics, 90th ed.; Lide, D. R., Ed.; CRC Press: Boca Raton, FL, 2009; p 4-90. (30) Onyestyak, Gy.; Lonyi, F.; Valyon, J. J. Therm. Anal. Calorim. 2005, 79, 561. (31) Peapples-Montgomery, P. B.; Seff, K. J. Phys. Chem. 1992, 96, 5962. (32) Seff, K. J. Phys. Chem. B 2005, 109, 13840. (33) Seff, K. Microporous Mesoporous Mater. 2005, 85, 351. (34) Sun, T.; Seff, K.; Heo, N. H.; Petranovskii, V. P. Science 1993, 259, 495. (35) Sun, T.; Seff, K.; Heo, N. H.; Petranovskii, V. P. J. Phys. Chem. 1994, 98, 5768. (36) Heo, N. H.; Seff, K. J. Am. Chem. Soc. 1987, 109, 7986. (37) Song, S. H.; Kim, U. S.; Kim, Y.; Seff, K. J. Phys. Chem. 1992, 96, 10937. (38) Lee, S. H.; Kim, Y.; Seff, K. J. Phys. Chem. B 2000, 104, 11162. (39) Zhen, S.; Bae, D.; Seff, K. J. Phys. Chem. B 2000, 104, 515. (40) Zhen, S.; Bae, D.; Seff, K. J. Phys. Chem. B 2001, 105, 12222. (41) Zhen, S.; Seff, K. J. Phys. Chem. B 1999, 103, 6493. (42) Abu-Zied, B. M.; Schwieger, W.; Unger, A. Appl. Catal., B 2008, 84, 277. (43) Frey, A. M.; Mert, S.; Due-Hanson, J.; Fehrmann, R.; Christensen, C. H. Catal. Lett. 2009, 130, 1. (44) Price, G. L.; Kanazirev, V. J. Catal. 1990, 126, 267. (45) Kanazirev, V.; Dimitrova, R.; Price, G. L.; Khodakov, A. Yu.; Kustov, L. M.; Kazansky, V. B. J. Mol. Catal. 1991, 70, 111. (46) Kanazirev, V.; Valtchev, V.; Tarassov, M. P. J. Chem. Soc., Chem. Commun. 1994, 1043. (47) Beyer, H. K.; Mihalyi, R. M.; Minchev, Ch.; Nienska, Y.; Kanazirev, V. Microporous Mater. 1996, 7, 333. (48) Mihalyi, R. M.; Pal-Borbely, G.; Beyer, H. K.; Michev, Ch.; Nienska, Y.; Karge, H. G. React. Kinet. Catal. Lett. 1997, 60, 195. (49) Schmidt, C.; Sowade, T.; Loffler, E.; Birkner, A.; Grunert, W. J. Phys. Chem. B 2002, 106, 4085. (50) Solt, H.; Lonyi, F.; Mihalyi, R. M.; Valyon, J.; Guttierrez, L. B.; Miro, E. E. J. Phys. Chem. C 2008, 112, 19423. (51) Mihalyi, R. M.; Schay, Z.; Szegedi, A. Catal. Today 2009, 143, 253.
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