Patent Description:
Crystalline materials are classified by the Structure Commission of the International Zeolite Association according to the rules of the IUPAC Commission on Zeolite Nomenclature. According to this classification, framework type zeolites and other crystalline microporous crystalline materials, for which a structure has been established, are assigned a three letter code and are described in the <NPL>).

One known crystalline material for which a structure has been established is the material designated with MFI framework-type, most notably including ZSM-<NUM>. Crystalline ZSM-<NUM> and its conventional preparation using tetrapropylammonium cations as a structure directing agent, are taught by <CIT> and <CIT>, Conventional ZSM-<NUM> has a distinctive X-ray diffraction pattern which distinguishes it from other known crystalline materials and is a highly versatile catalyst useful in a variety of organic conversion reactions.

Another known crystalline material structure is MEL, also known as ZSM-<NUM>, which is described in detail in <CIT>, MFI and MEL framework-type crystalline materials have similar structures and are frequently co-produced in zeolite synthesis processes as intergrown or disordered materials.

For some acid-catalyzed reactions over zeolites, it is beneficial to reduce diffusion lengths of the reagent and/or product molecules by employing a zeolite with a reduced crystal size and hence an increased external surface area. This may have the effect of reducing the shape selective effects of the zeolite, but for reactions that require only strong activity this may not be important. For example, the increased external surface area permits reactions with larger molecules that cannot enter the pores of the zeolite. In addition, in some processes it has been observed that the rate of deactivation is reduced when the external surface area of the ZSM-<NUM> zeolite is increased. See, for example, <NPL> <NPL>). Increased external surface area has also been reported to improve the propylene yields in methanol conversion. See, for example, <NPL>.

An example of small crystal ZSM-<NUM> is disclosed in <CIT>, in which the ZSM-<NUM> is in the form of platelets having first and second major dimensions of at least about <NUM> micron, preferably at least about <NUM> micron, and a minor third dimension of less than about <NUM> micron, preferably less than about <NUM> micron. The ZSM-<NUM> has a mesitylene sorption capacity of at least <NUM> weight % and is produced using precipitated silica as the silica source either in the absence of an organic directing agent or using n-propylamine as the directing agent.

In addition, in <NPL>et al. claim synthesizing ZSM-<NUM> crystals as small as <NUM> to <NUM> using a dual template of tetrapropylammonium (TPA) ions and phenylaminopropyltrimethoxysilane. In this method, the silanizing agent is introduced after the synthesis gel is pre-heated for short periods of time before the onset of zeolite crystallization. <FIG> of Serrano et al. shows a schematic representation of the crystallized products, whereas <FIG> shows TEM images of the product. Although these TEM images show very small particles, the peaks in the powder XRD of the product from this work are consistent with crystals exceeding <NUM> to <NUM> in their dimensions.

Ryoo and coworkers have reported in "<NPL>), the synthesis of a single unit cell-thick version of ZSM-<NUM> by using a single templating agent composed of a <NUM>-carbon atom alkyl chain and two quaternary ammonium groups separated by a methylene chain of <NUM> carbon atoms. Here the quaternary ammonium groups are located within the single-unit cell nanosheets, which are separated from one another by the long alkyl chains. <FIG> of Ryoo et al. shows a schematic of the unilamellar and multilamellar version of the ZSM-<NUM> crystals that are a single unit cell in thickness.

<CIT> describes a crystalline material designated as EMM-<NUM> and having the framework structure of ZSM-<NUM> comprising crystals having an external surface area in excess of <NUM><NUM>/g (as determined by the t-plot method for nitrogen physisorption) and a unique X-ray diffraction pattern. The crystalline material may be synthesized in the presence of an organic structure directing agent (Q) selected from one or more of <NUM>,<NUM>-bis(N-pentylpyrrolidinium)butane dications, <NUM>,<NUM>-bis(N-pentylpyrrolidinium)pentane dications, or <NUM>,<NUM>-bis(N-pentylpyrrolidinium)hexane dications.

In <NUM>, Zhang et al. reported the synthesis of a "self-pillared" MFI or MFI/MEL-type materials using tetrabutylphosphonium hydroxide (TBPOH) and/or tetrabutylammonium (TBAOH) as the structure-directing agent (SDA). See "<NPL>. TEM of the reported products shows a morphology composed of thin sheets of zeolite that are about <NUM> unit cell in width. The thin sheets interpenetrate one another at right angles to form a cross-hatched network of crystals with mesopores between them that are <NUM>-<NUM> in size. The resulting "house-of-cards" arrangement of the nanosheets creates a permanent network of <NUM>- to <NUM>-nanometer mesopores, which, along with the high external surface area and reduced micropore diffusion length, account for higher reaction rates for bulky molecules relative to those of other mesoporous and conventional MFI zeolites. The publication reported only materials with gel Si/Al ≥ <NUM>.

Despite these advances, a need still exists for new ultra-small crystal forms of MFI and MEL framework-type crystalline materials with higher external surface areas and to extend the Si/Al range over which these materials can be synthesized.

According to the invention, it has now been found that, although the self-pillaring effect observed by Zhang et al. is difficult to reproduce particularly at gel Si/Al ratios < <NUM>, high surface area MFI and/or MFI/MEL framework-type crystalline materials can still be produced at low Si/Al ratios using TBPOH and TBAOH as the SDA by reducing the water content and/or the Group <NUM> cation level of the gel. In fact, in some cases it has been possible to produce MFI and/or MFI/MEL framework-type crystalline materials with external and/or total surface areas higher than previously reported.

Thus, in a first aspect, the invention resides in a process for producing a crystalline material having the MFI and/or MFI/MEL framework-type, the process comprising: (i) preparing a synthesis mixture capable of forming the crystalline material, the mixture comprising a source of an oxide of a tetravalent element Y, a source of a trivalent element X, a source of an alkali and/or alkaline earth metal (M), water, and a directing agent (Q<NUM>) comprising tetrabutylammonium cations, and/or tetrabutylphosphonium cations, wherein X includes aluminum and Y includes silicon, and wherein the synthesis mixture has at least one of (a) H<NUM>O/YO<NUM> molar ratio of less than <NUM>, and (b) YO<NUM>/X<NUM>O<NUM> molar ratio of at least <NUM> and less than <NUM>, and (c) MI YO<NUM> molar ratio of <NUM> or less; (ii) heating the mixture under crystallization conditions including a temperature of from <NUM> to <NUM> and a time from <NUM> hours to <NUM> days until crystals of the crystalline material are formed; and (iii) recovering the crystalline material from step (ii).

In a second aspect, the present disclosure includes a process for producing a crystalline material having the MFI and/or MEL framework-type, the process comprising: (i) preparing a synthesis mixture capable of forming the crystalline material, said mixture comprising a source of an oxide of a tetravalent element Y, optionally a source of a trivalent element X, optionally a source of an alkali or alkaline earth metal (M), water, and a directing agent (Q<NUM>) comprising1,<NUM>-bis(N-tributylammonium)pentane dications, and/or <NUM>,<NUM>-bis(N-tributylammonium)hexane dications; (ii) heating the mixture under crystallization conditions including a temperature of from <NUM> to <NUM> and a time from <NUM> day to <NUM> days until crystals of the crystalline material are formed; and (iii) recovering the crystalline material from step (ii).

In a third aspect, the present disclosure includes a crystalline material having within its pore structure <NUM>,<NUM>-bis(N-tributylammonium)pentane dications, and/or <NUM>,<NUM>-bis(N-tributylammonium)hexane dications.

In a fourth aspect, the present disclosure includes a crystalline material having the MFI and/or MEL framework-type and a chemical composition comprising the molar relationship (n)YO<NUM>:X<NUM>O<NUM>, wherein n is a number of at least <NUM> and less then <NUM>, for example less than <NUM>, X is a trivalent element and Y is a tetravalent element and wherein the crystalline material comprises crystals having a total surface area (as determined by the t-plot method for nitrogen physisorption) in excess of <NUM><NUM>/g and/or an external surface area (as determined by the t-plot method for nitrogen physisorption) in excess of <NUM><NUM>/g.

In a fifth aspect, the present disclosure includes an organic nitrogen compound comprising a dication having formula (I) or (II):
<CHM>
<CHM>.

Described herein are processes of producing crystalline materials having an MFI and/or MFI/MEL framework-type and to small crystal forms of such crystalline materials having uniquely high external and/or total surface areas.

In some embodiments, the crystalline phase of the crystalline material produced by the present process comprises substantially MFI framework-type material, particularly ZSM-<NUM>. In some embodiments, the crystalline phase of the crystalline material may contain non-trivial quantities of MEL framework-type material, particularly ZSM-<NUM>, such as at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt%, or at least <NUM> wt% of MEL framework-type material. In some embodiments, the crystalline phase of the crystalline material produced by the present process can comprise substantially entirely MEL framework-type material, particularly ZSM-<NUM>.

As conventionally synthesized, for example in the presence of tetrapropylammonium cations as taught by <CIT> and <CIT>, a typical preparation of ZSM-<NUM> has an X-ray diffraction pattern including the characteristic lines listed in Table <NUM> below:.

As conventionally synthesized, for example in the presence of tetrabutylammonium cations as taught by <CIT>, a typical preparation of ZSM-<NUM> has an X-ray diffraction pattern including the characteristic lines listed in Table <NUM> below:.

The crystalline material produced by the inventive process may have X-ray diffraction peaks solely associated with ZSM-<NUM> (MFI) and/or with ZSM-<NUM> (MEL) materials. In particular, the crystalline material produced by the inventive process may, in its as-synthesized form, exhibit an X-ray diffraction pattern including the characteristic peak maxima listed in Table <NUM> below:.

The X-ray diffraction data reported herein were collected with a Panalytical X'Pert Pro™ diffraction system with an Xcelerator™ multichannel detector, equipped with a germanium solid state detector, using copper K-alpha radiation. The diffraction data were recorded by step-scanning at ∼<NUM> degrees two-theta, where theta is the Bragg angle, and using an effective counting time of ~<NUM> seconds for each step. The interplanar spacings, d-spacings, were calculated in Angstrom units, and the relative intensities of the lines, I/Io, represents the ratio of the peak intensity to the intensity of the strongest line, above background. The intensities are uncorrected for Lorentz and polarization effects. The relative intensities are given in terms of the symbols vs=very strong (<NUM>-<NUM>), s=strong (<NUM>-<NUM>), m=medium (<NUM>-<NUM>) and w=weak (<NUM>-<NUM>). In certain embodiments, one, some, or all of the relative intensities indicated as including w (weak) can be non-zero values.

It is known that certain lines in the X-ray patterns of zeolites can tend to broaden as the relevant dimension of the zeolite crystal decreases, so that adjacent lines may begin to overlap and thereby appear as only partially resolved peaks or as unresolved broad peaks. In certain embodiments of the crystalline materials described herein, particularly the ultra-small crystal materials described below, this line broadening may result in there being only a single diffuse composite feature in the two-theta range from about <NUM>° to about <NUM>° (d-spacing range from ∼<NUM>. 13Å to ~<NUM>. 42Å) of the X-ray pattern. In such cases, the maximum of the composite peak near <NUM> ± <NUM> degrees two-theta and the maximum of the composite peak near <NUM> ± <NUM> degrees two-theta can either appear as shoulders or can form part of a large diffuse composite peak with a maximum near <NUM> (± <NUM>) degrees two-theta.

In a powder XRD pattern of a typical (larger crystallite) ZSM-<NUM> sample, the composite peak with a maximum near <NUM> degrees two-theta and the composite peak near <NUM> degrees two-theta can intersect to form a clearly visible local minimum [see <FIG>]. In these typical ZSM-<NUM> preparations, the ratio of the relative background-subtracted intensity of this local minimum (Imin) to the relative background-subtracted intensity of the composite peak near <NUM> degrees two-theta (Imax) can be less than <NUM> in both the as-made and calcined forms of the zeolite product. In some embodiments of the present ultra-small crystal material, the local minimum may still be clearly discerned from the composite peak near <NUM> degrees two-theta, even where the Imin/Imax ratio can be at least about <NUM>. In certain embodiments, the crystals can become so small and the peaks so severely broadened that the peak maximum near <NUM> degrees two-theta either can appear as an inflection point of the large diffuse composite peak with a maximum near <NUM> (± <NUM>) degrees two-theta or can evidence no local maximum or inflection point for the composite peak near <NUM> (± <NUM>) degrees two-theta. In these extreme cases, the Imin/Imax ratio can approach <NUM>.

Similarly, in typical ZSM-<NUM> preparations, the composite peak with a maximum near <NUM> (± <NUM>) degrees two-theta and the composite peak with a maximum near <NUM> (± <NUM>) degrees two-theta can intersect to form a clearly visible local minimum [see <FIG>], in which the ratio of the relative background-subtracted intensity of this local minimum (Imin) to the relative background-subtracted intensity of the composite peak near <NUM> degrees two-theta (Imax) can be less than <NUM> in both the as-made and calcined forms of the zeolite. In contrast, in the calcined version of the inventive ultra-small crystal material, the Imin/Imax ratio can be at least <NUM>, or greater than <NUM>. In certain situations (with the inventive ultra-small crystals), the Imin/Imax ratio can be at least <NUM>. It should be borne in mind that, in cases where preferred orientation effects may be present, care should be taken to reduce/minimize their effects on X-ray patterns.

Most of the syntheses described herein produce MFI and/or MEL framework-type crystalline materials having a small crystal, such that the total surface area of the crystalline phase can be at least about <NUM><NUM>/g and external surface area can be at least about <NUM><NUM>/g. However, in certain ultra-small crystal embodiments of the present invention, the crystalline materials described herein can comprise crystals having a total surface area of least about <NUM><NUM>/g, for example at least about <NUM><NUM>/g or at least about <NUM><NUM>/g, such as from about <NUM><NUM>/g to about <NUM><NUM>/g. Alternatively or additionally, the ultra-small crystalline materials described herein may comprise crystals having an external surface area of at least <NUM><NUM>/g, for example at least about <NUM><NUM>/g or at least about <NUM><NUM>/g, such as from about <NUM><NUM>/g to about <NUM><NUM>/g or from about <NUM><NUM>/g to about <NUM><NUM>/g. Such values are believed to be higher than any previously reported for MFI and MEL framework-type crystalline materials. All surface area values given herein are determined from nitrogen physisorption data using the t-plot method. Details of this method can be found in <NPL>).

Because the syntheses described herein produce such ultra-small crystal sizes (e.g., less than <NUM> microns), any crystal size measurements/distributions should be (and are herein) done using a transmission electron microscope (TEM) in transmission mode. Average crystal size (diameter) measurements represent a mean of size (diameter) measurements made on at least <NUM> different crystals. Thus, in certain ultra-small crystal embodiments of the present invention, the crystalline materials described herein can comprise crystals having average sizes (diameters) of about <NUM> or less (e.g., about <NUM> or less, about <NUM> or less, about <NUM> or less, about <NUM> or less, or about <NUM> or less) and optionally at least about <NUM> (e.g., at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>). Additionally or alternatively, the crystalline materials described herein can comprise crystals having an average size (diameter) distribution with substantially no sizes (diameters) above about <NUM> (e.g., above about <NUM>, above about <NUM>, above about <NUM>, above about <NUM>, above about <NUM>, or above about <NUM>). In this context of size distribution, "substantially no" should be understood to mean <NUM>% or less, e.g., <NUM>% or less, <NUM>% or less, <NUM>% or less, or completely no.

It should be appreciated that, with such ultra-small crystal materials, X-ray diffraction may not be fully sufficient to identify the material as having the MFI or MEL structure, in which case other analytical methods, such as high resolution transmission electron microscopy and electron diffraction, may be necessary to confirm the identity of the material as MFI and/or MEL framework type.

The MFI and/or MEL framework type crystalline materials described herein can have a composition comprising the molar relationship:.

wherein X is an optional trivalent element, such as boron, aluminum, iron, and/or gallium, desirably at least including aluminum, Y is a tetravalent element, such as silicon, germanium, tin, titanium, and/or zirconium, desirably at least including silicon, and n is at least about <NUM>, for example at least about <NUM> or at least about <NUM>. In some embodiments, in which the trivalent element is present, n may be about <NUM> or less, for example about <NUM> or less or about <NUM> or less. In a particularly advantageous embodiment, n can be less than about <NUM>, optionally in tandem with one or more minimum values of n discussed hereinabove.

In certain process embodiments of the present invention, MFI and/or MFI/MEL framework type crystalline materials, including ultra-small crystal size forms thereof, may be produced in the presence of tetrabutylammonium cations and/or tetrabutylphosphonium cations as a structure directing agent (Q<NUM>). In these embodiments, a synthesis mixture can be produced containing a source of the Q<NUM> cations, such as the hydroxide and/or the halide (e.g., fluoride, chloride, bromide, and/or iodide, optionally excluding the fluoride in some embodiments), together with a source of an oxide of the tetravalent element Y, a source of the trivalent element X, a source of an alkali and/or alkaline earth metal (M), and water, such that the synthesis mixture has a molar composition comprising: (a) H<NUM>O/YO<NUM> molar ratio of less than <NUM>, for example at least <NUM>, such as from <NUM> to <NUM>; and (b) YO<NUM>/X<NUM>O<NUM> molar ratio of at least <NUM> and less than <NUM>, such as from <NUM> to <NUM>.

The synthesis mixture also has an M/YO<NUM> molar ratio of <NUM> to less than <NUM>, for example <NUM> to <NUM>, from greater than <NUM> to less than <NUM>, or from greater than <NUM> to <NUM>.

In particular, as will be demonstrated by the following Examples, it is found that the production of small crystal materials with high total and external surface areas can be favored when the H<NUM>O/YO<NUM> molar ratio and/or the M/YO<NUM> molar ratio are reduced.

In addition, the synthesis mixture may have a molar composition comprising the following:.

In other process embodiments of the present disclosure, MFI and/or MEL framework-type materials, including ultra-small crystal size forms thereof, may be produced in the presence of <NUM>,<NUM>-bis(N-tributylammonium)pentane dications, and/or <NUM>,<NUM>-bis(N-tributylammonium)hexane dications. as a structure directing agent (Q<NUM>). Such diquats are believed to be novel and have formulas (I) and (II) respectively:
<CHM>
<CHM>.

The materials of formulas (I) and (II) can readily be produced by reaction of tributylamine with <NUM>,<NUM>-dibromopentane or <NUM>,<NUM>-dibromohexane.

In these other process embodiments using Q<NUM> as the structure directing agent, a synthesis mixture is produced containing a source of the Q<NUM> cations, such as the hydroxide and/or the halide (e.g., fluoride, chloride, bromide, and/or iodide, optionally excluding the fluoride in some embodiments), together with a source of an oxide of the tetravalent element Y, optionally a source of the trivalent element X, optionally a source of an alkali or alkaline earth metal (M), and water such that the synthesis mixture has a molar composition comprising the following ratios:.

Again, it has been unexpectedly found that the production of small crystal materials with high total and external surface areas can be favored when the H<NUM>O/YO<NUM> molar ratio and/or the M/YO<NUM> molar ratio are reduced. Thus, in some embodiments, the H<NUM>O/YO<NUM> mole ratio may be about <NUM> or less, for example about <NUM> or less. Additionally or alternatively, M/YO<NUM> mole ratio of the synthesis mixture may be about <NUM> or less, for example about <NUM> or less or about <NUM> or less.

Suitable sources of the tetravalent element Y in the synthesis mixture described above include colloidal suspensions of silica, fumed silicas, precipitated silicas, alkali metal silicates, tetraalkyl orthosilicates, the like, or a combination thereof. Suitable sources of aluminum can include, inter alia, hydrated alumina and/or water-soluble aluminum salts, such as aluminum nitrate. Combined sources of aluminum and silicon may include clays and/or treated clays, such as metakaolin. Other combined sources of X and Y, including aluminosilicates such as zeolite Y, may additionally or alternatively be used.

In some embodiments, the synthesis mixture may comprise seeds of a crystalline material, such as ZSM-<NUM> from a previous synthesis, desirably in an amount from about <NUM> wppm to about <NUM> wppm, such as from about <NUM> wppm to about <NUM> wppm, based on the weight of the synthesis mixture.

Crystallization of MFI and/or MFI/MEL framework type crystalline materials from the above synthesis mixtures can be carried out at static, tumbled, or stirred conditions in a suitable reactor vessel, e.g., polypropylene jars or Teflon™-lined or stainless steel autoclaves, at a temperature of about <NUM> to about <NUM>, for example about <NUM> to about <NUM>, for a time sufficient for crystallization to occur at the temperature used, e.g., from about <NUM> hours to about <NUM> days, from about <NUM> hours to about <NUM> days, or from about <NUM> day to about <NUM> days. Thereafter, the crystals can be separated from the liquid and recovered.

To the extent desired and depending on the X<NUM>O<NUM>/YO<NUM> molar ratio of the material, any alkali and/or alkaline earth metal cations in the as-synthesized material can be replaced in accordance with techniques well known in the art, e.g., by ion exchange with other cations. Exemplary replacing cations can include metal ions, hydrogen ions, hydrogen ion precursors (e.g., ammonium ions), or mixtures thereof. In certain embodiments, particularly preferred cations can include those with which the catalytic activity can be specifically tailored for certain hydrocarbon conversion reactions. These can include, but are not necessarily limited to, hydrogen, rare earth metals, metals of Groups <NUM> to <NUM> of the Periodic Table of the Elements, and combinations thereof. As used herein, the numbering scheme for the Periodic Table Groups is as disclosed in <NPL>).

The as-synthesized crystalline material may further be subjected to treatment to remove all or part of the organic directing agent(s) Q1/Q2 used in its synthesis. This can be conveniently achieved/attempted by thermal treatment, for example, in which the as-synthesized material can be heated at a temperature of at least about <NUM> for at least <NUM> minute and generally not longer than <NUM> hours. While subatmospheric pressure can be employed for the thermal treatment, atmospheric and/or superatmospheric pressures can typically desired for reasons of convenience. The thermal treatment can be performed at a temperature up to about <NUM>. Alternatively, the organic directing agent(s) Q1/Q2 can be removed by treatment with ozone (see, e.g.,<NPL>). The organic-decomposed/-free product, especially in its metal, hydrogen, and/or ammonium forms, can be particularly useful in the catalysis of certain organic (e.g., hydrocarbon) conversion reactions.

The inventive crystalline material can be intimately combined with a hydrogenating component, such as comprising molybdenum, rhenium, nickel, cobalt, chromium, manganese, and/or a noble metal (such as platinum and/or palladium), where a hydrogenation-dehydrogenation function can be desired. Such component can be in the composition by way of co-crystallization, exchanged into the composition to the extent a Group IIIA element (e.g., aluminum) is in the structure, impregnated therein, or intimately physically admixed therewith. Such component can be impregnated into/onto it such as, for example, in the case of platinum, by treating the silicate with a solution containing a platinum metal-containing ion. Thus, suitable platinum compounds for this purpose can include chloroplatinic acid, platinous chloride, and/or various compounds containing a platinum-amine complex.

The present crystalline material, when employed either as an adsorbent or as a catalyst, should be at least partially dehydrated. This can be done by heating to a temperature, e.g., in the range of <NUM> to about <NUM> in an atmosphere such as air, nitrogen, etc., and at atmospheric, subatmospheric, or superatmospheric pressures for a sufficient time, e.g., between <NUM> minutes and <NUM> hours. Dehydration can additionally or alternatively be performed at room temperature merely by placing the crystalline material in a vacuum, but a longer time may be required to obtain a sufficient amount of dehydration.

The crystalline materials described herein can be used as an adsorbent or, particularly in its aluminosilicate form, as a catalyst to facilitate one or more of a wide variety of organic compound conversion processes, including many of present commercial/industrial importance. Examples of chemical conversion processes which could be effectively catalyzed by the inventive crystalline materials can advantageously those where relatively high acid activity and large surface area can be important.

As in the case of many catalysts, it may be desirable to incorporate the inventive crystalline materials with another material resistant to the temperatures and other conditions employed in organic conversion processes. Such materials can include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica, and/or other metal oxides such as alumina. The latter may be naturally occurring or in the form of gelatinous precipitates or gels including mixtures of silica and other metal oxides. Use of a material in conjunction with the inventive crystalline materials (i.e., combined therewith or present during synthesis of the new crystal), which are in their active form(s), can tend to change the conversion and/or selectivity of the catalyst in certain organic conversion processes. Inactive materials can suitably serve as diluents to control the amount of conversion in a given process, so that products can be obtained in an economic and orderly manner without employing other means for controlling the rate of reaction. These materials may be incorporated into naturally occurring clays, e.g., bentonite and kaolin, to improve the crush strength of the catalyst under commercial operating conditions. Said materials (i.e., clays, oxides, etc.) can function as binders for the catalyst. It can be desirable to provide a catalyst having good crush strength, because, in commercial use, it can be particularly desirable to prevent the catalyst from attrition into powder-like materials. These clay and/or oxide binders have been employed normally primarily for the purpose of improving the crush strength of the catalyst.

Naturally occurring clays that can be composited with the inventive crystalline materials can include the montmorillonite and kaolin family, which families include the subbentonites, and the kaolins commonly known as Dixie, McNamee, Georgia, and Florida clays or others in which the main mineral constituent is halloysite, kaolinite, dickite, nacrite, or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid treatment, or chemical modification. Other useful binders can include inorganic oxides, such as silica, zirconia, titania, magnesia, beryllia, alumina, and mixtures thereof.

In addition to the foregoing materials, the inventive crystalline materials can be composited with a porous matrix material such as silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania, or ternary compositions such as silica-alumina-thoria, silica-alumina-zirconia silica-alumina-magnesia, and silica-magnesia-zirconia.

The relative proportions of MFI and/or MEL framework-type crystalline material and inorganic oxide matrix may vary widely, with the sieve content ranging from about <NUM> wt% to about <NUM> wt% and more usually, particularly when the composite is prepared in the form of beads, in the range from about <NUM> wt% to about <NUM> wt% of the composite.

The invention will now be more particularly described with reference to the following Examples and the accompanying drawings.

An MFI synthesis similar to that reported by <NPL>; discussed above) was conducted using tetrabutylphosphonium hydroxide (TBPOH) as the structure directing agent (SDA) and with a molar gel composition of -<NUM> TBPOH:∼<NUM>. 0125NaOH:∼<NUM> Al<NUM>O<NUM>:~<NUM> SiO<NUM>:~<NUM><NUM>O: ~4EtOH. The presence of ethanol in this synthesis came from the use of tetraethylorthosilicate (TEOS) as the silica source - once hydrolyzed in water, each TEOS can produce approximately four molecules of ethanol. The alumina source was aluminum sulfate. After ~<NUM> days of heating under tumbling conditions at ∼<NUM>, this synthesis yielded a product with a very high total surface area of ∼<NUM><NUM>/g and an external surface area of ∼<NUM><NUM>/g. These high surface areas appear to be consistent with those expected for materials with very small crystals.

The powder XRD pattern of the as-synthesized product of Example <NUM> is shown in <FIG>, with SEM images of the product shown in <FIG>. At the magnification of the SEM, no faceted domains seem to be discernible. <FIG> shows HRTEM images of the same material. Several images were collected on different areas of the product, and no amorphous domains were observed. Unlike the products reported by Zhang et al. , the products here do not appear to exhibit an orderly "self-pillared" arrangement. However, there are many small crystals that are overlapping and arranged at different orientations relative to one another. The thicknesses of the various crystals do not appear to be uniform. In a few cases, crystals that appear -<NUM>-<NUM> units cell in thickness can be discerned - these are surrounded by transparent boxes. The fringes within these crystals appear to have characteristics of MFI and/or MEL materials. In the middle image, the pores of the MFI framework-type can be seen - the distance between the pores matches those in other MFI and/or MEL materials.

The synthesis of Example <NUM> was repeated using Ultrasil™ precipitated silica in place of TEOS and tetrabutylammonium hydroxide (TBAOH) as the structure directing agent (SDA). The molar composition of the gel was ∼<NUM> TBAOH: ~<NUM>. 010NaOH:~<NUM> Al<NUM>O<NUM>:∼<NUM> SiO<NUM>:~<NUM><NUM>O. No ethanol was added for this preparation. In this case, the synthesis appeared to be complete after ~<NUM> days of heating at ∼<NUM>. Without being bound by theory, although this synthesis used a different SDA and a different silica source, the faster crystallization time could be due to the absence of the ethanol rather than to the different nature of the silica sources. The total surface area of this material was ∼<NUM><NUM>/g and the external surface area was ~<NUM><NUM>/g. The total surface area was notably greater than the <NUM><NUM>/g measured for the unilamellar preparations by <NPL>; discussed herein) and is believed to be one of the highest surface areas reported for any MFI-type material.

<FIG> compares the powder XRD patterns of the products of Examples <NUM> and <NUM> and appears to show in each broad features characteristic of materials with very small crystals. After calcination, shown in <FIG> for the product of Example <NUM>, there appeared to be increases in the relative intensities of the low-angle features often observed in microporous materials. One apparent consequence of the small crystal dimensions can be that many of the distinct peaks from a "normal" ZSM-<NUM> appeared as shoulders or formed broad bumps with their neighboring peaks. Notably, the valley between the first low-angle peaks possesses an intensity greater than half the intensity of the peak around <NUM>° two-theta.

The synthesis of Example <NUM> was repeated in ~<NUM>-mL and ~<NUM>-mL tumbled autoclaves, using TEOS as the silica source and aluminum isopropoxide as the aluminum source. The molar composition of the gel was -<NUM> TBPOH: ~<NUM>. 0125NaOH:~<NUM> Al<NUM>O<NUM>:~<NUM> SiO<NUM>:~<NUM><NUM>O:~4EtOH. Because more aluminous preparations of ZSM-<NUM> can generally require more time than those with higher Si/Al ratios, a higher temperature of ~<NUM> was employed. After ∼<NUM> days of heating, and subsequent calcination at ~<NUM>, a product with ∼<NUM><NUM>/g total BET surface area and an external surface area of ∼<NUM><NUM>/g was obtained. When the product was analyzed in its uncalcined form, the same external surface area was measured, but no micropore volume was observed (presumably because the SDA remained within the micropores).

The synthesis of Example <NUM> was repeated on a larger scale in a ~<NUM>-mL, overhead-stirred autoclave. After ∼<NUM> days of heating, a product with only ∼<NUM><NUM>/g total BET and ∼<NUM><NUM>/g external surface area was obtained. These numbers are more representative of typical samples of ZSM-<NUM>. The features in the powder pattern of this material were much sharper than those of the material prepared from the tumbled reactors. Without being bound by theory, although a definitive explanation for the variation in crystal sizes is not currently available, the surface areas of products from the overhead-stirred systems can frequently appear lower than in tumbled systems.

The syntheses of Examples <NUM> and <NUM> were repeated but using aluminum sulfate and Ultrasil™ as the aluminum and silica sources, respectively, under otherwise identical conditions. After ∼<NUM> days of heating under tumbled conditions, a product with ∼<NUM><NUM>/g total and ~<NUM><NUM>/g external surface area was obtained. When the synthesis was repeated in a ∼<NUM>-mL, overhead-stirred autoclave, the total and external surface areas were reduced to ∼<NUM><NUM>/g and ∼<NUM><NUM>/g (<NUM>/<NUM>), respectively. Again, the overhead-stirred system appeared to yield a product with lower surface area, but the differences were not as notable as observed in the system of Examples <NUM> and <NUM>, utilizing TEOS and aluminum isopropoxide.

A series of experiments were performed at different temperatures at a SiO<NUM>/Al<NUM>O<NUM> molar ratio of ~<NUM> in the aluminum sulfate/Ultrasil™ system. Each synthesis was carried out in a ~<NUM>-mL overhead stirred autoclave using TBPOH as the SDA and involving an H<NUM>O/SiO<NUM> molar ratio of ~<NUM>. After ~<NUM> days of heating at ~<NUM>, the product appeared to possess a relatively sharp powder XRD pattern. When the synthesis was repeated at ~<NUM> for ~<NUM> days, the product had total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g. At ~<NUM> for ~<NUM> days, the total/external surface areas increased to ∼<NUM>/∼<NUM><NUM>/g. At ~<NUM> for ~<NUM> days, the corresponding numbers were ∼<NUM>/∼<NUM><NUM>/g. Thus, the decrease in temperature from ~<NUM> to ~<NUM> did not appear to produce much change in the total measured BET surface areas, but the contribution of the external surface area appeared enhanced. <FIG> shows the broadening that occurred in the features of the powder XRD patterns of the products obtained, as synthesis temperature was decreased.

A series of experiments similar to Example <NUM> were conducted but with the gel compositions having a SiO<NUM>/Al<NUM>O<NUM> molar ratio of ∼<NUM>. The first experiment in a ~<NUM>-mL autoclave at ~<NUM> for ∼<NUM> days gave a product with total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g. When the experiment was repeated but only heated for ~<NUM> days, the surface area numbers increased to ∼<NUM>/∼<NUM><NUM>/g. In a ~<NUM>-mL tumbled autoclave heated at ~<NUM> for ~<NUM> days, the numbers increased further to ∼<NUM>/∼<NUM><NUM>/g. Another synthesis was performed in a ~<NUM>-mL overhead-stirred autoclave with a staged heating sequence in which the gel was heated at ~<NUM> for ~<NUM> days and then ~<NUM> for ~<NUM> more days. In that case, the total/external surface areas were ∼<NUM>/∼<NUM><NUM>/g, which was about the same as the product obtained from ~<NUM> days of heating at ~<NUM>.

When the experiments of Example <NUM> were repeated in tumbled ~<NUM>-mL reactors, there appeared to be a clear trend in the observed total/external surface areas: at ~<NUM> for ~<NUM> days, the resulting surface areas were ∼<NUM>/∼<NUM><NUM>/g; at ~<NUM> for ~<NUM> days, the resulting surface areas were ∼<NUM>/∼<NUM><NUM>/g; and at ~<NUM> for ∼<NUM> days, the resulting surface areas were ~<NUM>/~<NUM><NUM>/g.

The experiments of Example <NUM> were again repeated, but with lower SiO<NUM>/Al<NUM>O<NUM> molar ratios of ~<NUM> and ~<NUM>. The experiment with SiO<NUM>/Al<NUM>O<NUM> molar ratio of ~<NUM> employed TEOS and aluminum isopropoxide. The experiment with SiO<NUM>/Al<NUM>O<NUM> molar ratio of ~<NUM> employed Ultrasil™ and aluminum sulfate. After heating for at least ~<NUM> days at ~<NUM> and ~<NUM>, respectively, both experiments appeared to produce only amorphous phases. It was noted that he lower Si/Al ratios of the gel and in any resultant product typically correlate with a need for a higher concentration of sodium to assist in crystallization. The Na/SiO<NUM> molar ratio of the gels in these experiments remained low at ∼<NUM>.

When the experiments were repeated with gel SiO<NUM>/Al<NUM>O<NUM> molar ratio of ~<NUM> and an increased Na/SiO<NUM> molar ratio of ~<NUM>, relatively sharp, fully crystalline ZSM-<NUM> products were obtained after only ~<NUM> days of heating at both ~<NUM> and ~<NUM>. Even at ~<NUM>, a relatively sharp ZSM-<NUM> product was observed. Introducing extra sodium into the system can allow a more aluminous product to form, but the increased sodium level can also promote the formation of larger crystallites. Hence, in such systems where very small crystals are desired, it can be important to reduce and/or minimize the concentration of sodium, to prevent the formation of larger crystals.

A series of experiments were conducted at the ~<NUM>-mL scale with TBAOH as the SDA under concentrated conditions (H<NUM>O/Si ratio ≈ <NUM>). To obtain these low H<NUM>O/Si ratios, water was removed from the ∼<NUM>% TBAOH solution using a rotary evaporator at ~<NUM> to obtain a ∼<NUM>% TBAOH solution (∼<NUM> mmol/g). Typically, concentrating an SDA solution under elevated temperatures is not desirable, as it can lead to Hofmann elimination. In this case, although there was discoloration of the gel after the removal of the water, no degradation was observable by NMR analysis. Zeolite synthesis with a gel SiO<NUM>/Al<NUM>O<NUM> molar ratio of ~<NUM> at ~<NUM> for ~<NUM> days yielded a product with total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g. A similar preparation with an SiO<NUM>/Al<NUM>O<NUM> molar ratio of ~<NUM> at ~<NUM> for ~<NUM> days yielded a product with total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g.

A series of experiments were conducted using <NUM>,<NUM>-bis(N-tributylammonium)pentane hydroxide as the SDA. This C5-diquat was produced by adding ∼<NUM> tributylamine to ~<NUM> acetonitrile, followed by addition of ∼<NUM> of <NUM>,<NUM>-dibromopentane. The mixture was then heated for ~<NUM> days at ~<NUM> inside of a sealed Teflon™ container. The product was then isolated by rotary evaporation of the solvent, rinsing the oil with ether, decanting the ether, and then rotary evaporating under vacuum (reduced pressure) at ~<NUM> until solids appeared to form. The solids were then slurried in an acetone/ether mixture, isolated by filtration, and allowed to dry. The purity of the product was verified by <NUM>H and <NUM>C NMR. The solid was then exchanged into its hydroxide form using Dowex™ exchange resin.

The resultant SDA solution was concentrated by rotary evaporation to about <NUM>% by mass and was then used to prepare a gel having a molar composition of ∼<NUM> C5-Diquat:∼<NUM>. 0125NaOH:∼<NUM> Al<NUM>O<NUM>:∼<NUM> SiO<NUM>:~<NUM><NUM>O. After ~<NUM> days of heating at ~<NUM>, the gel yielded a product with total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g. When the experiment was repeated with the H<NUM>O/SiO<NUM> ratio increased to ∼<NUM>, the product obtained after ~<NUM> days of heating at ~<NUM> had total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g. In another experiment, another portion of the gel with the H<NUM>O/SiO<NUM> ratio of ∼<NUM> was heated at ~<NUM> for ∼<NUM> days and yielded a product with total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g.

In certain experiments, the C5-diquat SDA appeared to need more time and/or higher temperatures to provide similar structural products than for the TBAOH SDA.

A series of experiments similar to those of Example <NUM> were conducted but using <NUM>,<NUM>-bis(N-tributylammonium)pentane hydroxide as the SDA. This C6-diquat was produced in the same way as the C5-diquat but by substituting <NUM>,<NUM>-dibromohexane for the <NUM>,<NUM>-dibromopentane. Again the resultant SDA solution was concentrated by rotary evaporation to about <NUM>% by mass before being used in the synthesis reactions below.

The first syntheses with the C6-diquat were done at ~<NUM> for ∼<NUM> days. At an H<NUM>O/SiO<NUM> ratio of ∼<NUM>, the product had total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g, and, at an H<NUM>O/SiO<NUM> ratio of ∼<NUM>, the product had total/external surface areas of ~<NUM>/~<NUM><NUM>/g. When the synthesis at the H<NUM>O/SiO<NUM> ratio of ~<NUM> was repeated at ~<NUM> for ∼<NUM> days, the total/external surface areas were ∼<NUM>/∼<NUM><NUM>/g. Next, the syntheses were repeated with H<NUM>O/SiO<NUM> ratios of ~<NUM> at ~<NUM> and ~<NUM> using seeds. After ~<NUM> days of heating at ~<NUM>, the product had measured total/external surface areas of ~<NUM>/~<NUM><NUM>/g, and, after ~<NUM> days of heating at ~<NUM>, the product had measured total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g.

Without being bound by theory, the significantly reduced crystallization times with the C6-diquat, as compared with the C5-diquat, suggest that the distances between the N centers of the C6 diquat may be a good match to that distance between the intersections of the product framework-type structure. Moreover, although the crystallization can be accomplished quicker, the ability to produce materials with small crystals appeared to have been retained.

The products of the preparations in highly concentrated media have typically been isolated by centrifugation, followed by washing, because the particles are typically filtered through the fritted funnels. An experiment was therefore conducted to test whether the centrifugation/washing steps could be avoided by simply drying the crystallized gel and then calcining the entire product (to remove the SDA). Such a simplified finishing process could be advantageous for larger scale production. One potential concern for such a streamlined process is that excess alkali cations could degrade the zeolite during calcination, if they function as basic species. However, this was unlikely to occur in the inventive syntheses, which were run at relatively low sodium/Si ratios. Another potential concern for such a streamlined process is that, in most systems, a non-trivial amount of silica generally remains dissolved in solution - calcination of such a dried product with could likely result in amorphous material or in other undesirable high-silica phases/diluents. However, this too was unlikely to occur in the inventive syntheses, because, in relatively low water-to-silica systems, there is little excess water, and much of what excess water exists is typically bound to the surface are of the very small crystallite products, causing the yields in these concentrated systems to be relatively high (close to <NUM>%, or at least ><NUM>%).

Thus, a portion of the as-synthesized product of Example <NUM> generated at ~<NUM> for ~<NUM> days was run without washing the product. The XRD spectrum of this product is shown in the lower portion of <FIG>. The unwashed product was then calcined to ~<NUM> and again analyzed by XRD. The resultant pattern is shown in the top portion of <FIG>, and no significant amorphitization of the product was observed. <FIG> shows the <NUM>Al NMR before and after calcination of the product to ~<NUM> to remove the SDA. Before calcination, all of the aluminum can be in a tetrahedral environment. Surprisingly, after calcination, ion-exchange, and subsequent re-calcination, only about <NUM>-<NUM>% of the aluminum becomes octahedral. Contrarily, in typical ZSM-<NUM> materials, at least <NUM>% of the aluminum becomes octahedral after calcination.

The process of Example <NUM> with the C6-diquat was repeated at a gel SiO<NUM>/Al<NUM>O<NUM> molar ratio of ~<NUM> and a H<NUM>O/SiO<NUM> molar ratio of ~<NUM> without the addition of any sodium and in the presence of ~<NUM> wt% ZSM-<NUM> seeds. After about five days of heating at ~<NUM>, a crystalline product was obtained with total/external surface areas of ~<NUM>/~<NUM><NUM>/g. By not using sodium in this synthesis, the product could be directly calcined, without requiring either a prior or a subsequent ion-exchange to convert the zeolite to its fully acidic form.

The process of Example <NUM> was repeated with SiO<NUM>/Al<NUM>O<NUM> molar ratios of ~<NUM> (Example <NUM>) and ∼<NUM> (Example <NUM>) at a temperature of ~<NUM>. After heating for ∼<NUM> and ∼<NUM> days, respectively, products were obtained with total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g and ∼<NUM>/∼<NUM><NUM>/g. Decreasing the temperature appeared to result in a large increase in surface area of the product, but more time appeared to be required for the crystallization. <FIG> shows powder XRD patterns of the products of Example <NUM> taken after different heating periods. Between ∼<NUM> and ∼<NUM> days, there appeared only a slight sharpening of the mid-angle features, indicating that the synthesis may have been complete at ∼<NUM> days. <FIG> shows a comparison of the XRD patterns of the as-made and calcined products of Example <NUM> obtained after ∼<NUM> days of heating at ~<NUM>. <FIG> shows TEM images of the calcined product of Example <NUM> obtained after ∼<NUM> days of heating at ~<NUM>, and <FIG> shows a bar graph of the crystal size distribution. Because the crystals are believed to be in the form of thin plates, these distributions may represent only the larger crystal dimensions (diameters). The distribution in <FIG> represents crystal size measurements made by TEM in transmission mode. Random areas of each TEM grid/holder containing the sample were used. The number of random areas can be varied, based on the number of resolvable particles in any given area, such that at least <NUM> particles can be measured in all areas for each sample. To eliminate any bias, it is best practice to use at least <NUM> random areas. For each particle under visual inspection, the appropriate magnification was used to capture an average dimension (diameter) for each resolvable particle. The mean of the size distribution of all measured particles was used herein to represent the "average" crystal dimension (diameter).

The results of Examples <NUM>-<NUM> demonstrated that even relatively small concentrations of sodium can have dramatic effects on the crystallization time and on the final product morphologies. To investigate the potential influence of the anion associated with the aluminum source, two otherwise identical syntheses were conducted, one using aluminum chloride (Example <NUM>) as the aluminum source and the other using aluminum nitrate (Example <NUM>). In each case, the synthesis gel employed the C6-diquat of Example <NUM> and had the following molar composition: ~1SiO<NUM>: ~<NUM>. 04Al+<NUM>:~<NUM><NUM>O:~<NUM> SDA(OH)<NUM>:~<NUM>. Each synthesis was carried out in a new Teflon™ liner, to avoid the potential influence of different concentrations of sodium from used liners (which are typically cleaned in sodium hydroxide after each use). Both syntheses were placed inside the same oven at the same time under tumbling conditions and then removed after heating for the same period of time (∼<NUM> days at ~<NUM>). <FIG> compares the XRD powder patterns of the products. The spectrum of the product from the synthesis with aluminum chloride appeared to have somewhat broader peaks than that prepared from aluminum nitrate. Its total surface area was negligibly higher (∼<NUM> vs ∼<NUM><NUM>/g), but its external surface area was almost <NUM><NUM>/g higher. These isolated results suggest that the nature and concentration of the anions in the synthesis also have an influence on the morphologies of their respective products.

The process of Example <NUM> was repeated with the C6-diquat/SiO<NUM> molar ratio reduced from ∼<NUM> to ∼<NUM> and the H<NUM>O/SiO<NUM> molar ratio increased to ∼<NUM>∼<NUM>. In addition, Alcoa C-<NUM>™ aluminum (aluminum trihydrate) was used as the aluminum source. After heating for ~<NUM> days at ~<NUM>, a product was obtained with total/external surface areas of ∼<NUM>/∼<NUM><NUM>/g.

A series of experiments similar to those of Example <NUM> were conducted but using <NUM>,<NUM>-bis(N-tributylammonium)butane hydroxide as the SDA. This C4-diquat was produced in the same way as the C5-diquat but by substituting <NUM>,<NUM>-dibromobutane for <NUM>,<NUM>-dibromopentane.

The C4 diquat preparations did not appear to produce any crystalline phases after several weeks of heating at ~<NUM> under H<NUM>O/Si ratios of ∼<NUM> and ∼<NUM>.

A series of borosilicate analogues of the materials produced in the preceding Examples were produced using boric acid as the boron source and the C6 diquat of Example <NUM> as the SDA. The first synthesis (Example <NUM>) used an Na/SiO<NUM> ratio of ∼<NUM> and was conducted at ∼<NUM> for ~<NUM> days. After the product was calcined, it possessed a total/external surface area of ∼<NUM>/∼<NUM><NUM>/g. Without being bound by theory, it was speculated that this lower-than-expected surface area could be due to the sodium in the synthesis and subsequent product. When the synthesis was repeated with no alkali cations (Example <NUM>), with heating at ~<NUM> for ∼<NUM> days, the surface areas increased to ~<NUM>/~<NUM><NUM>/g. <FIG> shows the powder XRD patterns of the as-made products of each of these preparations. As was observed previously in the aluminosilicate systems, the absence of sodium appeared to implicate longer crystallization times, but its absence also appeared to produce products with broader powder diffraction peaks (indicating much smaller crystals).

The preparations of Examples <NUM> and <NUM> were repeated using TBAOH rather than the C6 diquat as the SDA. After ∼<NUM> days at ~<NUM>, the synthesis mixture with a SiO<NUM>/Al<NUM>O<NUM> molar ratio of ∼<NUM> (Example <NUM>) yielded a product with a total/ external surface area of ∼<NUM>/∼<NUM><NUM>/g, while, after -<NUM> days at ~<NUM>, the synthesis mixture with a SiO<NUM>/Al<NUM>O<NUM> molar ratio of ∼<NUM> (Example <NUM>) yielded a product with a total/external surface area of ∼<NUM>/∼<NUM><NUM>/g.

Claim 1:
A process for producing a crystalline material having the MFI framework-type or the MFI and MEL framework-type, the process comprising:
(i) preparing a synthesis mixture capable of forming the crystalline material, the mixture comprising a source of an oxide of a tetravalent element Y, a source of a trivalent element X, a source of an alkali and/or alkaline earth metal M, water, and a directing agent (Q<NUM>) comprising tetrabutylammonium cations and/or tetrabutylphosphonium cations, wherein X includes aluminum, and Y includes silicon, and wherein the synthesis mixture has a composition comprising:
(a) H<NUM>O/YO<NUM> molar ratio of <NUM> or less; and
(b) YO<NUM>/X<NUM>O<NUM> molar ratio of at least <NUM> and less than <NUM>; and
(c) M/YO<NUM> molar ratio of <NUM> or less;
(ii) heating the mixture under crystallization conditions including a temperature from <NUM> to <NUM> and a time from <NUM> hours to <NUM> days until crystals of the crystalline material are formed; and
(iii) recovering the crystalline material from step (ii).