BACKGROUND OF THE INVENTION Both natural and synthetic crystalline aluminosilicates are known and may generally be described as alumino-silicates of ordered internal structure having the following general formula: M2/nO : A1203 : YSiO2 : ZH20 where M is a cation, n is its valence, Y the moles of silica, and Z the moles of the water of hydration.

When water of hydration is removed from the crystalline aluminosilicates, highly porous crystalline bodies are formed which contain extremely large adsorption areas inside each crystal. Cavities in the crystal structure lead to internal pores and form an interconnecting network of passages. The size of the pores is substantially constant, and this property has led to the use of crystalline aluminosilicates for the separation of materials according to molecular size or shape. For this reason, the crystalline aluminosilicates have sometimes been referred to as molecular sieves.

The crystalline structure of such molecular sieves consists of basically of three-dimensional frameworks of Sied and Al04 tetrahedra. Isomorphous substitution of boron or gallium for aluminum in a zeolite framework may be achieved. The tetrahedra are cross-linked by the sharing of oxygen atoms, and the electrovalence of the tetrahedra containing aluminum is balanced by the inclusion in the crystal of a cation, e. g., alkaki metal or alkaline earth metal ions or other cationic metals and various combinations thereof. These cations are generally readily replaced by conventional ion-exchange techniques.

The spaces in the crystals between the tetrahedra ordinarily are occupied by water. When the crystals are treated to remove the water, the spaces remaining are available for adsorption of other molecules of a size and shape which permits their entry into the pores of the structure.

Molecular sieves have found application in a variety of processes which include ion exchange, selective adsorption and separation of compounds having different molecular dimensions such as hydrocarbon isomers, and the catalytic conversion of organic materials, especially catalytic cracking processes.

Faujasite is arguably the most valuable of the zeolite molecular sieves. Faujasite zeolites have been synthesized with a wide range of compositions, from a low-silica zeolite X with a Si/Al ratio of 1.0 to zeolite Y with Si/Al ratio as high as 5. Y zeolites with even higher Si/Al ratios have been obtained by dealumination such as by steam or other chemical treatments. Faujasites have been used widely in such applications such as adsorption, ionic exchange and

catalysis and, accordingly, the utility of faujasite in these areas cannot be overstated.

Faujasite forms into two possible polymorphs, cubic and hexagonal. Cubic faujasite has long been known and is by far, the most known and utilized of the two polymorph forms.

Substantial work has gone into preparing high silica versions of hexagonal faujasite in order to rival the widely utilized high silica cubic faujasite employed in catalytic cracking. While results of academic interest have been obtained for hexagonal faujasite, the synthesis of hexagonal faujasite in high silica form has proven impractical.

Delprado, et. al. have disclosed the formation of hexagonal faujasite with Si/Al ratios between 3 to 5 in which the use of organic structure directing agents such as 18-crown-6 ether have been added to the sources of alumina and silica, Zeolites, 10 (1990) 546. U. S. Patent No. 5,098,686 broadly discloses formation of hexagonal faujasite with Si/Al ratios greater than 1.0 formed with the crown ether templates, but no example of hexagonal faujasites. with Si/Al ratios less than 3.7 are provided.

Recently, researchers have reported the preparation of low silica intergrowths of hexagonal and cubic faujasite in order to prepare alternatives to widely employed high aluminum cubic faujasite adsorbents and ion-exchange materials. Low silica zeolites have potential uses in laundry detergents and air separation adsorbents, both of which benefit from the highest possible ion-exchange capacity of zeolites. In the cubic form, low silica faujasite is widely referred to as zeolite X.

In an article entitled,"Synthesis and Characterization of VPI-6"by Mark E. Davis, Molecular Sieves, (1992), pp.

60-69, a crystalline zeolite having a cubic and hexagonal

intergrowth in the faujasite structure is disclosed. The synthesis of the zeolite involves aging a solution for twenty-four hours and the article indicates that aging is an important criteria of the synthesis. The utility of the VPI-6 zeolite is recited to be as an adsorbent or ion- exchange medium. Silica to alumina ratios of greater than 2 to 3 are disclosed. The article states that they were unable to crystallize VPI-6 with a framework composition of Si02/Al203 equal to 2.

J. L. Lievens, et. al. in an article,"Cation Site Energies In Dehydrated Hexagonal Faujasite", appearing in ZEOLITES, 1992, Vol. 12, July/August, pp. 698-705, reviews properties of hexagonal faujasite designated as EMT.

FAU/EMT intergrowths were also discerned in the studied EMT materials. Sodium was the cation which was involved in the cation site studies, and Si/Al ratios of 4.6 were specified.

U. S. Patent No. 5,116,590 discloses a zeolitic structure, ECR-35, which has a Si/Al ratio of 2: 1 to 12: 1, preferably 4. ECR-35 is an intergrowth of faujasite and Breck Structure Six (a nomenclature for hexagonal faujasite, subsequently EMT). Cation sites are occupied by tetraethylammonium and methyltriethylammonium cations.

Recently, U. S. Patent Nos. 5,573,745; 5,562,756 and 5,567,407, assigned to Air Products and Chemicals Co., Inc. have attempted to develop hexagonal faujasite (EMT) structures with Si/Al ratios of less than 1.4 for use in air separation. The patents describe lithium exchanged structures. While there is broad mention of forming the low silica EMT structures, the structures formed in these patents are EMT/FAU intergrowths in which the hexagonal faujasite portion is less than 50%. The adaption of high aluminum, hexagonal faujasite in the lithium cation

exchanged form as disclosed in these Air Products patents is logical inasmuch as the lithium cationic exchanged form of zeolite X (cubic faujasite) represents the current state of the art for air separation adsorbents.

Researchers have encountered substantial difficulty in elevating the aluminum content of hexagonal faujasite to its maximum theoretical level, as well as difficulty in making the relatively pure hexagonal polymorph of the material.

Both VPI-6 and the EMT/FAU structures disclosed in the Air Products patents are not structures in which the predominant polymorph of the faujasite is hexagonal. While the Air Products patents, in particular U. S. Patent No. 5,567,407, claims a crystalline metallosilicate composition comprising an EMT structure with a Si/X ratio of less than 1.4, none of the examples in this patent or any of the other related patents produce an EMT structure wherein a majority of the hexagonal phase was present as determined by XRD scrutiny.

In both the Davis article (VPI-6) and the Air Products patents, hexagonal faujasite with Si/Al ratios below 1.2 were never observed. This compositional"wall"at Si/Al ratios of 1.2 is analogous to the synthesis of cubic faujasite where such a barrier existed between X and low silica X for many years. Cubic faujasite approaching 1/1 Si/Al is still widely considered difficult to make. Li and Armor, Microporous Materials 9 (1997), pp. 51-57, in an article entitled"Low-Silica EMT/FAU Intergrowth Zeolites With Si/Al Equal 1.0" report the preparation of a low-silica EMT/FAU intergrowth. However, the intergrowth, is predominantly cubic (FAU) and made by an impractical recrystallization of template-formed materials using the process of Delprado, et. al., described above. Even the Air Products patents mentioned above use a complicated process

for preparing the EMT/FAU intergrowths involving the formation of separate gels and the mixture of the gels prior to additional heat treatment.

The prior art has failed to provide a crystalline aluminosilicate zeolite in the form of substantially pure hexagonal faujasite wherein the Si/Al is less than 1.2.

Further, the prior art has not yet provided a simplified method for the synthesis of hexagonal faujasite whether as substantially pure hexagonal faujasite or hexagonal faujasite/cubic faujasite intergrowths.

SUMMARY OF THE INVENTION The present invention is directed to novel, low silica faujasites comprising substantially pure hexagonal polymorph, as well as mixed intergrowths of cubic and hexagonal faujasite comprising a majority of the hexagonal polymorph. Surprisingly, these low silica, hexagonal faujasites may be prepared in a high silica environment in which the Si/Al ratio in the reaction mixture is in excess of unity. Moreover, unlike the complicated multi-step processes of the prior art for producing hexagonal faujasites, this invention is directed to a novel, simplified method involving a one-step addition to water of a silica source, an alumina source, an optional electrolyte, and an alkali metal hydroxide and then crystallizing faujasites from the resultant highly alkaline/high silica environment. The low silica hexagonal faujasites have high ion-exchange capacity and show extreme promise as water softening agents and detergent builders, and may find other applications in complexing multivalent cations such as in the removal of calcium from sugars and fatty oils or in

removing heavy metals such as lead from various fluid streams.

The novel low silica, hexagonal faujasites of this invention and designated ECZ are substantially pure hexagonal faujasite. Hexagonal faujasites having a Si/Al ratio of less than or equal to about 1.2 have been prepared.

The novel low silica intergrowths of cubic and hexagonal faujasite of this invention and designated EHX contain a majority of hexagonal faujasite, a minority of cubic faujasite, and have been prepared with Si/Al ratios of less than or equal to about 1.5.

Generally speaking, the novel, simplified methods of producing low silica hexagonal faujasite including low silica intergrowths of same comprise the steps of: combining in water, the ingredients comprising an alkali metal hydroxide, a solid aluminum source, a silica source, and an optional electrolyte; mixing the ingredients at slow speed in a container ; maintaining the pH at or above 12.0 for the pure hexagonal faujasite, at or above 8.0 for the hexagonal faujasite intergrowths; reacting the mixture at a temperature and for a period of time necessary to produce a faujasite; filtering the solid faujasite produced; washing the faujasite filtrate; and drying the washed faujasite filtrate overnight.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a graph correlating the concentration of silicate species vs. pH for sodium silicate solutions. The figure is a copy of the figure appearing in H. Van Bekkum, et. al. *"Introduction to Zeolite Science and Practice", Elsevier Science Publishers, 1991 (94).

FIG. 2 shows an X-Ray Diffraction (XRD) pattern of the inventive ECZ in degrees of from 0 to 40° (29) vs. intensity.

FIG. 3 shows an XRD pattern of the inventive ECZ in degrees of from 4.0 to 8.0° (20) vs. intensity.

FIG. 4 shows an XRD pattern of the inventive EHX in degrees of from 0 to 40° (26).

FIG. 5 shows an XRD pattern of the inventive EHX in degrees of from 4.0 to 8.0° (20).

DETAILED DESCRIPTION OF THE INVENTION It is now possible to obtain either low silica hexagonal faujasites or low silica mixed intergrowths of cubic and hexagonal faujasite, with Si/Al ratios previously found only in state of the art low silica cubic faujasites.

Surprisingly, the inventors have found that these low Si/Al ratios may be obtained when an excess of silica is used to form the inventive faujasites. Further, in contrast to the more complex prior art methods of producing hexagonal faujasites, including intergrowths of same, involving mixing separately prepared gels together, use of crown ethers as templates or extensive aging, the present inventors have found that hexagonal faujasites may be produced by a new, simplified method in which all of the reactants are added, mixed and heated in one step and without use of organic templates or required aging.

The synthesis of low silica zeolites is not unknown.

For example, the preparation of zeolite A having the maximum aluminum content has been well established. The high aluminum zeolite A has been employed as an ion-exchange agent, especially useful in water softening applications

such as detergent building. With a Si/Al ratio of 1.00, the lowest possible for a zeolite according to the Rule of Lowenstein, low silica zeolites such as zeolite A have been typically prepared in high aluminum environments. Contrary to such preparation methods, the present assignee has prepared zeolite A in high silica environments. U. S. Patent No. 5,948,383 is such an example.

The present inventors have now found that low silica hexagonal faujasites can also be prepared in high silica- containing reaction mediums. For preparing high aluminum zeolites and achieving Si/Al ratios approaching 1.00 in the hexagonal faujasites of the present invention, the employment of a silica-enriched environment is counter- intuitive. While not wishing to be bound by any theory of operation, it appears that when a highly alkaline solution is employed for zeolite synthesis, silica is somewhat depolymerized to either its monomer, dimer, or trimer forms, depending upon the precise alkalinity and pH employed, while at the same time, repolymerization is inhibited (Fig. 1).

It appears that the high silica content also retards alumina polymerization. The combination of the two effects, silica depolymerization and inhibition of alumina polymerization, results in the formation of a great number of 1: 1 Si/Al chains. In the formation of the inventive hexagonal faujasite (ECZ) and inventive cubic/hexagonal faujasites (EHX), the pH and alkalinity can be adjusted and maintained at a level to yield a silica form which results in the formation of the desired zeolite. Thus, for preparation of ECZ, the pH and alkalinity are adjusted and maintained at a level such that the silica source exists substantially in the monomeric form. When the inventive mixed intergrowths of cubic and hexagonal faujasite (EHX) are desired, the pH

and alkalinity are adjusted and maintained at a level in which the silica exists substantially in the dimeric or trimeric forms.

After preparation in the high silica, highly alkaline environment, the resulting hexagonal faujasites exhibit Si/Al ratios lower than that exhibited by the prior art.

The Si/Al ratios also compare favorably with the prior art cubic faujasites.

It has also been discovered that the elevation of the electrolyte concentration in faujasite synthesis mixtures beyond that inherent to the caustic necessary for synthesis results in enhancement of the reaction kinetics for preparation of the inventive faujasites. The present assignee discloses this phenomenon in copending U. S. Serial No. 09/533,707, the entire content of which is herein incorporated by reference. Such salt addition has also been found to result in the formation of smaller crystals.

The novel low silica faujasites will now be discussed in greater detail.

The crystalline zeolite hexagonal faujasites of this invention, ECZ, representing the substantially pure hexagonal polymorph and EHX representing the hexagonal/cubic intergrowth structure preferably have the chemical composition: M2/nO : Al203 : (2.0 to 3.0) Si02 : (0-10) H20 wherein M equals one or more metal cations having a valence of n. Although not preferred, the aluminum can be replaced with gallium or boron. The metal cation M can typically be sodium, potassium, lithium, magnesium, zinc, nickel, manganese and mixtures thereof.

The substantially pure hexagonal faujasite of this invention (ECZ) has a structure substantially equivalent to the hexagonal character of the synthetic faujasite recognized as EMT. EMT is a recognized zeolitic crystal structure of the Structure Commission of the International Zeolite Association. EHX is an intergrowth of the hexagonal zeolite ECZ and the cubic faujasite structure which has been designated under the code as FAU. ECZ structure consists of sodalite cages that join through double 6-ring pores in a hexagonal symmetry. The FAU structure consists of sodalite cages joined through double 6-ring pores in a cubic symmetry. The EHX intergrowths are formed when the cubic faujasite and ECZ phases stack to each other within the zeolite crystal, wherein the domain sizes and composition of each phase can vary. In accordance with the present invention, the intergrowths EHX can be made in which the hexagonal phase predominates.

Substantially pure hexagonal faujasite ECZ with silica to alumina ratios of less than or equal to 1.2 and intergrowth structures of hexagonal/cubic faujasite in which the crystal contains a majority of the hexagonal polymorph and having a silica to alumina ratio of less than or equal to 1.5 have not previously been synthesized. An important aspect in obtaining the substantially pure hexagonal polymorph and the intergrowth in which a majority of the hexagonal polymorph is obtained is the synthesis method which is utilized.

Unexpectedly, the inventors have found that by reacting the appropriate amount of silica in excess of that required for the desired Si/A1 ratio of 1: 1 in the final zeolite product, one may obtain either low silica faujasite containing substantially pure hexagonal faujasite (ECZ), or

low silica intergrowths of cubic and hexagonal faujasite (EHX) containing a majority of hexagonal faujasite, both of which have a Si/Al ratio lower than that disclosed or taught by the prior art. Si/Al ratios provided in the reaction medium should be at least equal to or greater than 1.05, preferably equal to or greater than 1.25 to form low silica ECZ. Si/Al ratios in the reaction medium above 2.0 do not appear to provide any advantage. Preferred Si/Al ratios in the reaction medium are 1.1 to 1.35. The inventive hexagonal faujasite ECZ has been formed with zeolite Si/Al ratios of equal to or less than 1.2 with Si/Al ratios of less than 1.10 being typical. The example provided below illustrates the formation of ECZ with a Si/Al ratio of less than 1.05. Similarly, the inventive intergrowths of cubic and hexagonal faujasite EHX can be made from reaction solutions which have Si/Al ratios of from 1.2 to less than 5.00, preferably from 1. 25 to 1.60. The final EHX product which has been formed from such reaction solutions typically have Si/Al ratios of less than 1.5, preferably less than 1.25, still more preferably less than 1.15.

The novel simplified method for producing the inventive low silica faujasites will now be discussed in greater detail.

First, a source of solid alumina, an optional electrolyte, and a silica source (in excess of alumina), are combined with an alkali metal hydroxide, including aqueous solutions of an alkali metal hydroxide), and mixed together.

Mixing at slow speeds is preferred. Generally, slow speed means rotater speeds of less than 750 RPM, more typically at 500 RPM or less.

The solid alumina source may be selected from the group consisting of alumina, dried silica-alumina gels, bauxite,

gibbsite, boehmite, and clays such as calcined or raw uncalcined kaolin. The ability to use raw reactants such as uncalcined kaolin may substantively impact the economics of faujasite production. Among metakaolins, those low in iron and titania are preferred when color is a consideration.

For example, metakaolin having a Fe203 content below 1% by weight, preferably below 0.5% by weight, and a Ti02 content below 2% by weight, preferably below 1% by weight are useful. The metakaolin should be in powder form. These powders may be prepared by removing grit and coarse impurities from kaolin ores, usually by fractionating the degritted crude, drying the resulting slurry of fractionated hydrous kaolin, pulverizing the dried material, calcining in conventional manner to produce metakaolin (see, for example, U. S. Pat. No. 3,112,176), and pulverizing the metakaolin by means of a hammer mill or the like. Calcined kaolin pigments may be produced from acidic (bleached) filter cake of kaolin by steps including drying, pulverizing, calcining and repulverizing (see, for example, U. S. Pat. No.

3,014,836). In practice the calcination temperature of U. S.

Pat. No. 3,014,835 must be lowered to produced the desired metakaolin form of calcined clay. The kaolin ore may be upgraded by means such as froth flotation, magnetic purification, selective flocculation, mechanical delamination, grinding, or combinations thereof, before drying, pulverization, calcination and repulverization. In many commercial operations, a chemically dispersed slip of the kaolin is dried in a spray dryer, forming microspheres (see, for example, U. S. Pat. No. 3,586,523). The resulting microspheres of hydrous (uncalcined) kaolin are then pulverized, calcined and repulverized, as taught in U. S.

Pat. No. 3,586,523.

The silica source may be sodium silicate (including sodium orthosilicate, sodium disilicate, and sodium tetrasilicate). Generally, the silica source may be added in an amount as discussed above. The high amount of silica added not only unexpectedly yields a low Si/Al faujasite it also suppresses the formation of iron oxide, probably by the formation of uncolored iron silicate. This allows"white" faujasites to be grown. from natural reactants such as clays.

The alkali metal hydroxide or solution thereof may be selected from those containing lithium hydroxide, sodium hydroxide, or potassium hydroxide, with sodium hydroxide being preferred. The alkalinity and pH of the resultant aqueous mixture or the silica, alumina, optional electrolyte and alkali metal hydroxide (or solution thereof) are chosen depending upon the particular type of faujasite desired, i. e., hexagonal or mixed intergrowths of cubic and hexagonal. Preparation of the substantially pure hexagonal faujasite ECZ requires a pH of greater than or equal to about 12.0, in order to insure significant amounts of silica in the monomeric form. Preparation of the hexagonal faujasite intergrowths EHX requires a pH of greater than or equal to about 8.0 and less than or equal to about 12.0, in order to insure significant amounts of silica dimers and trimers.

The aqueous alkaline mixture of alumina and silica should be reacted at a temperature and for a period of time necessary to produce the faujasite final product. The temperature may range from about 20°C to about 110°C, preferably from about 50°C to about 80°C, and most preferably from about 60°C to about 70°C. The reaction time may range from about 8-28, preferably about 12-24, and most

preferably about 16-18 hours. The need for an extensive aging period prior to reaction at elevated temperature is not required for producing either ECZ or EHX hexagonal faujasites.

After the mixture has been reacted, the solid product may be filtered and then washed to remove sodium and spurious silica from the faujasite crystal surfaces.

Preferably, it may be washed four times with deionized water, but solutions other than water may be used. After washing, the washed faujasite filtrate may be dried, preferably overnight at about 100°C.

The optional electrolyte may be a salt selected from nitrates, phosphates, bicarbonates, carbonates, borates, nitrites, sulfates, chlorides, etc. Specific, non-limiting examples include sodium carbonate, trisodium polyphosphate (TSPP), sodium borate, as well as sodium chloride, among others. The level of added salt into the reaction mixture can vary widely. Generally speaking, it has been found that amounts of electrolyte corresponding to about 10% to about 100% by weight based on the aluminum-containing reactant yields increased rate and/or improvement in zeolite surface area.

The present invention will now be exemplified by specific examples as set forth below. For the examples, the XRD powder patterns were obtained using a Phillips diffractometer (PW1710-based) equipped with a theta compensator. The theta compensator maintains a constant area of illumination on the sample, so X-ray intensities obtained from a theta compensated unit are not directly comparable to those of a non-compensated unit. Thus, all values mentioned in the specification and claims with regard

to ECZ and EHX were determined by said theta compensated X- ray equipment. The radiation was the K-alpha doublet of copper, and a scintillation counter spectrometer was used.

The peak heights (I) and the positions as a function of 2 times theta (theta = Bragg angle) were read from the spectrometer chart. From these, the relative intensities, 100 I/Io, corresponding to the recorded lines were calculated, where Io is the intensity of the strongest line or peak, I is the intensity of the peak being measured, and d (obs.) is the interplanar spacing in A.

EXAMPLE 1 ECZ was prepared by combining an alumina source, silica source, alkali metal hydroxide, water, and electrolyte in the following proportions: metakaolin 100g N-Brand Sodium Silicate 130g NaOH 324g H20 445g Na2CO3 25g Each of the foregoing ingredients were mixed together in a plastic jar at 500 rpm, and then reacted at 65°C for 17 hours. The mixture was then filtered, and the filtrate washed 4 times and dried at 100°C overnight.

Figure 2 illustrates the X-ray diffraction pattern of the faujasite which was formed. The XRD pattern indicates a substantially pure hexagonal faujasite with its main peak 10 centered at a d-spacing of 15.230.2. The remaining peaks are consistent with typical fajausite XRD patterns. Figure 3 is a magnification of the XRD of Figure 2 between 4° and 8° (26) abscissa. The magnification clearly shows the three peak pattern of pure hexagonal faujasite in which the main

peak 12 is centered at a d-spacing of 15.230.2.

Chemical analysis of the faujasite indicated an Si/Al ratio of 1. 03.

EXAMPLE 2 The intergrowth EHX was prepared by combining an alumina source, silica source, alkali metal hydroxide, water, and electrolyte in the following proportions: gibbsite 50g N-Brand 340g NaOH 340g H20 320g TSPP log Each of the foregoing ingredients were mixed in a plastic jar at 500 rpm, and then reacted at 65°C for 17 hours. The mixture was then filtered, and the filtrate washed 4 times and dried at 100°C overnight.

Figure 4 sets forth the XRD pattern for the zeolite which was formed. The XRD pattern is consistent with the intergrowth EMT/FAU such as described in the Air Products and Chemicals, Inc. patents discussed above. Thus, a multiple peak system with two primary peaks 20,22 are provided at respective d-spacings of 15.140.2 and 14.61.02. This twin peak system can best be seen in Figure 5 as peaks 24,26. The remaining peaks in the XRD of Figure 4 are consistent with a typical faujasite. The intensity of peak 24 in Figure 5 is consistent with a faujasite containing a major portion of hexagonal polymorph.

Chemical analysis of the EHX intergrowth indicated an Si/Al ratio of 1.10.

Example 3 An ECZ sample was prepared by mixing 136.0 grams of N- Brand sodium silicate with 600.0 grams of water and 173.0 grams of solid NaOH pellets in a half-gallon plastic jar.

The mixture was stirred until all NaOH was dissolved and the solution appeared clear. At this point 200.0 grams of Metamax@ metakaolin was added to the alkaline silicate solution and mixed until it was dispersed into an apparently homogeneous suspension. This reactant mixture was placed in a constant temperature bath set at 60 degrees C. and stirred with an overhead stirrer to keep the solid particles in suspension for a period of 18 hours. The resultant crystalline product was vacuum filtered, washed repeatedly with deionized water and dried at 100 degrees C. An XRD powder pattern spectrum of the resultant product indicated that ECZ was the dominant component with a small amount 10%) of an aluminum-rich analog of Zeolite P and a trace (perhaps 1%) Zeolite A.

Example 4 The metakaolin-alkali silicate mixture of Example 3 was duplicated and reacted at 60 degrees C. for 18 hours without stirring. The crystalline product was found to be essentially pure Zeolite ECZ with no Zeolite P analog and a trace (perhaps 1%) Zeolite A.

Examples 3 and 4 demonstrate that Zeolite ECZ may be easily and quickly synthesized at relatively low temperature without autoclaving pressure from simple, inexpensive reactants in both stirred and static reactors.

Examples 5 through 11 demonstrate the breadth of the synthesis regime. In each case, a predetermined amount of Metamax0 metakaolin was mixed with a solution containing 600 grams of water, 181 grams of NaOH and 136 grams sodium silicate. The resultant mixtures were stirred and crystallized in a constant temperature bath at 60 degrees C. for 16 to 18 hours. The resultant products were washed and filtered with deionzied water, dried at 100 degrees C. and subjected to XRD powder pattern analysis.

Example 5 400 grams metakaolin was subjected to the above procedure. Low angle XRD analysis indicate that the primary product was classical faujasite (Zeolite X) with a peak centering at 14.3 angstroms.

Example 6 The metakaolin content of the above procedure is lowered to 350 grams. XRD analysis shows a central peak at 14.3 angstroms characteristic of Zeolite X. A shoulder at 15.2 angstroms is much more pronounced than found in Example 5. The zeolite formed is EHX.

Example 7 The metakaolin content of the above procedure is further lowered to 300 grams. XRD peaks at 14.3 and 15.2 angstroms are of nearly equivalent intensity. This represents an EHX intergrowth in which the hexagonal polymorph is clearly the major product.

Example 8 The metakaolin content of the above procedure is further lowered to 250 grams. The XRD peaks at 14.3 and 15.2 angstroms found are of essentially equivalent intensity. This Example provided the EHX intergrowth with the majority polymorph as hexagonal.

Examples 9,10 and 11 The metakaolin content of the above procedure is lowered to 100,75 and 50 grams respectively. In all three Examples, XRD shows a major peak centered at 15.2 angstroms distinctive for ECZ and hexagonal faujasite.

Once given the above disclosure, many other features, modifications, and improvements will become apparent to the skilled artisan. Such other features, modifications, and improvements are, therefore, considered to be a part of this invention, the scope of which is to be determined by the following claims.