MXPA00011351A - Preparation of zeolite l - Google Patents

Abstract

A method is disclosed for preparing crystalline aluminosilicate zeolite L from a reaction mixture containing only sufficient water to produce zeolite L. In one embodiment, the reaction mixture is self-supporting and may be shaped if desired. In the method, the reaction mixture is heated at crystallization conditions and in the absence of an added external liquid phase, so that excess liquid need not be removed from the crystallized product prior to drying the crystals.

Description

PREPARATION OF ZEOLITE FIELD OF THE INVENTION • The present invention describes a process for producing crystalline aluminosilicate L zeolite from a reaction mixture containing only enough water to form zeolite L. Background of the invention The foregoing methods of the art of The preparation of crystalline zeolite L typically produces finely divided crystals which can be separated from an excess of liquid in which the zeolite is crystallized. The liquid, in turn, must be treated for reuse or be discarded, with consequences potentially harmful environmental. The commercially useful preparation of the catalytic materials that • Contain the powdered zeolite also usually require ligatures and additional training stages. Typically, the zeolite powder as crystallized should be mixed with a binder material and then formed into particular particles or agglomerates, using methods such as extrusion, agglomeration, porous drying, and the like.

REF. DO NOT. 125269 greatly increase the complexity of the manufacture of the catalysts involving the zeolitic materials. The additional steps can also have an adverse effect on the catalytic performance of the zeolite Y in this way bound and formed. The U.S. patent No. 3,094,383, published June 18, 1963 for Dzierzanows i et al. describes a method for the manufacture of type A zeolites in the form of coherent polycrystalline aggregates by the formation reaction masses consisting of a mixture of sodium aluminate, a siliceous material and water, wherein the molar ratio of H20 / Na20 it is from 5 to 25. The mass is stabilized while remaining out of contact with an external aqueous liquid phase that prevents the mass from dehydration. The maturation step can include maintaining the dough at 100 ° F (38 ° C) for, for example, 18 hours, followed by heating to 200 ° F (93 ° C) for, for example, 24 hours. The U.S. patent No. 3,119,659, published on January 28, 1964 for Taggart et al. discloses a method for producing an aluminosilicate zeolite in a preformed body by providing an unreacted preformed body containing a reactive kaolin type clay and an alkali metal hydroxide, and reacting the preformed body in an aqueous reaction mixture until the crystals of the zeolite are formed in the body. The preformed body aggregate and the aqueous reactant mixture have a molar ratio of H20 / Na20 of at least 20. It is established that the zeolite can be manufactured in this manner. The U.S. Patent No. 3,216,789, published November 9, 1965 for Breck et al., Describes zeolite L. Zeolite L is prepared from reaction mixtures whose compositions, expressed in terms of molar ratios of oxides, fall within the ranges: or The U.S. Patent No. 4,058,586, published November 15, 1977 to Chi et al., Discloses a method for preparing zeolitic aluminosilicates, particularly those which are characterized by pores of sizes from 4 to 10 Angstroms which are designated Zeolites A and X, wherein the compact of Zeolites A and X, the mixture of metakaolin clay is subjected to a crystallization at a temperature of 200 ° to 700 ° F (93 ° to 371 ° C). The crystallization is carried out in a calcining oven or other drying equipment. Normally, the particles formed provide all the liquid needed for crystallization, although the current can be added during the crystallization process. The U.S. patent No. 5,064,630, published on November 12, 1991 to Verduijin, describes the preparation of zeolite L in a very small crystalline form, in which an alkaline reaction mixture comprising water, a source of silicon, an alkali metal source and a source of aluminum or gallium is heated to a temperature of at least 80 ° C, for a period of time long enough to form the zeolite L, the composition of the reaction mixture has the following molar proportions (expressed as oxides) : Where M is potassium or a mixture of potassium and one or more alkali metals. WO 94/13584, published on June 23, 1994, describes a method for the preparation of a crystalline aluminosilicate zeolite of a reaction mixture containing only sufficient water so that the reaction mixture can be formed if desired . In the method, the reaction mixture is heated to crystallization conditions and in the absence of an external liquid phase, so that the excess liquid does not need to be removed from the crystallized material prior to the drying of the crystals.

Patent GB 2,160,517 A, published on December 24, 1985, describes a preformed synthetic zeolite selected from the group consisting of Y, omega zeolite, ofretite, erionite, zeolite L and ferrite whose ranges of atomic ratio of Si / Al are 1.5 at 100, the preformed zeolite is obtained from a preformed aluminosilicic material whose atomic ratio of Si / Al is less than that of the product and ranges from 0.5 to 90 when treating the material with a product containing silica in the presence of at least an organic or inorganic base.

BRIEF DESCRIPTION OF THE INVENTION It is a purpose of the invention to provide a method for preparing crystalline zeolite L using a minimum of liquid for crystallization. It is a further purpose of the invention to provide a method for preparing crystalline L zeolite while minimizing aqueous wear. It is a further purpose of the invention to provide a method for preparing the zeolite L in the absence of the added binder substance. It is also a purpose of this invention to prepare the crystalline L zeolite in the form of a body. It is a further purpose of the invention to provide a method for preparing the zeolite L in commercially useful forms without any of the subsequent steps of formation of • crystallization. It is a further purpose of the invention to provide a method for preparing zeolite L having a small crystallite size. It is a further purpose of the invention to provide a method for preparing the zeolite L at the costs of the reduced raw materials. Thus, according to the present invention, there is provided a method for preparing crystalline zeolite L, said method comprising the preparation of a self-supporting reaction mixture comprising at least one source active silica, at least one active source of alumina and a source of hydroxide in sufficient quantities to • produce the zeolite L, and enough water to produce the zeolite L, where the reaction mixture has a molar ratio of 0H ~ / SiO2 from 0.20 to 0.40 and the heating said reaction mixture at a temperature of about 100 ° C. at about 200 ° C. under crystallization conditions and in the absence of an additional external liquid phase for a sufficient time to form the crystals of the zeolite L. The reaction mixture is extrudable and capable of maintaining a form. The present invention also provides a method for preparing crystalline zeolite L, said method comprising the preparation of a reaction mixture comprising at least one active source of silica, at least one active source of alumina and a hydroxide source in sufficient amounts to producing the zeolite L, and sufficient water to form said mixture, wherein the reaction mixture has a molar ratio OH ~ / SiO2 of 0.20 to 0.40, said reaction mixture forming in a body; and heating said reaction mixture at a temperature of about 100 ° C to about 200 ° C. under crystallization conditions and in the absence of an additional external liquid phase for a sufficient time to form zeolite L crystals. The reaction mixture is extrudable and capable of maintaining a form. It is important, in the preparation of the reaction mixture of the present process, that the amount of water present in the reaction mixture, prepared for the crystallization step, be sufficient to produce the zeolite L. In this way, the reaction mixture provides by itself all the water needed to crystallize the zeolite.

This amount of water is less than the amount of water required in the conventional processes for the preparation of the zeolites. This is an amount that is not • substantially larger than that required to produce the zeolite L. For example, the amount of water used in the present invention is less than that required to dissolve the components of the reaction mixture, or, if these are not dissolved, less that required to submerge the components of the reaction mixture in the water. A) Yes, • 10 during the crystallization stage according to the present process, there is no separation, the added external liquid phase present which must be removed from the crystallized material at the end of the crystallization stage by, for example, filtering or decanting, before drying of the crystals This absence of an added external liquid phase distinguishes the present invention from the methods for the manufacture of the zeolite L wherein the crystals of the zeollta L are formed from a solution or where the solid reactants are heated in an aqueous solution until the crystals of zeolite L are formed. While it is not a requirement to form the mixture in a body before the mixture is subject to crystallization conditions, it may be desirable in many cases to do so. In this case, the amount of water present in the reaction mixture is sufficient to form the reaction mixture in a body, but insufficient to cause the reaction mixture formed to collapse or "melt", ie, once the reaction mixture is formed in the desired form containing the desired amount of water, the resulting form is self-supported. Among other factors, the present invention is based on the discovery of a method for crystallizing the crystalline L zeolite from a reaction mixture which contains only enough water to form the zeolite L. In addition, the zeolite L prepared by the methods described above It is produced as very small crystallites. As discussed during the aforementioned intervention, the molar ratio 0H ~ / SiO2 is critical in the Applicant's claimed method for manufacturing the zeolite L. The applicant has discovered that this molar ratio affects both the physical properties of the reaction mixture as well as the degree of crystallization achieved. A critical balance can be carried out so that the reaction mixture has the desired physical properties, for example, it will be maintained self-supporting and capable of being formed, while at the same time providing an acceptable degree of crystallization. It has also been found that if the molar ratio OH ~ / Si02 becomes very high, the mixture of • reaction takes undesirable physical properties. On the other hand, if the molar ratio OH_ / SiO2 is too low, the crystallization is inadequate.

DETAILED DESCRIPTION OF THE INVENTION - PREPARATION OF THE REACTION MIXTURE • The reaction mixture of where and in which the zeolite L is crystallized comprises at least one active source of silica, at least one active source of alumina, and sufficient water to form zeolite L. This amount of water is considerably less than that required in the processes to prepare the zeolite L. The amount of water required in the reaction mixture of the present invention is the amount which is necessary to adequately mix the mixture. Thus, the reaction mixture is prepared by mixing water with sources Active zeolite to form a uniform mass preferably having a consistency similar to a heavy paste. The active sources will be in a form that can easily be mixed in a uniform mass, and can be, for example, powders, hydrated particles, or concentrated aqueous solutions. Sufficient water is added to moisten all the powders during mixing and molding stages. Alternatively, sufficient water 5 is added so that the powders can be molded into a uniform and generally homogeneous mixture that can be formed. It is not necessary for all active sources to be readily soluble in water during molding, since the water added to the active sources will be sufficient to • 10 produce a fluid type mixture. The amount of water added depends on the mixing devices and on the active sources used. Those familiar with the technique can quickly determine without undue experimentation the amount of liquid required to mix properly the active sources of the zeolite. For example, the hydrated sources of the zeolite can • require relatively less water, and dry sources may require relatively more. Although it is preferred that the mixture be combined and molded until the mixture has In a homogeneous and uniform appearance, the period of time spent molding the mixture is not critical in the present invention.

The water content of the reaction mixture after mixing and molding can be further adjusted, for example, by drying or adding water. When it is desired that the reaction mixture be formed in a body, adjusting the amount of water can facilitate the formation of the reaction mixture and ensure that it will be maintained by itself, that is, the body will not collapse or "melt" due to an excess of water in the reaction mixture. Typical sources of silicon oxide (SI02) include silicates, silica hydrogel, silicic acid, colloidal silica, fumed silica, hydroxides, silica, tetraalkyl orthosilicates, precipitated silica and clay. Typical sources of aluminum oxide (Al20) include aluminates, alumina, and aluminum compounds such as A1C13 A12 (S04) 3, aluminum hydroxide (Al (OH3)), and kaolin clay. An advantage of the present invention is that the sources of silicon oxide and aluminum oxide can all be non-zeolitic. Salts, particularly alkali metal halides such as sodium chloride, can be added to or formed in the reaction mixture. They are described in the literature as assistants in the crystallization of zeolites while preventing the occlusion of the silica in the grating. The reaction mixture also contains one or more active sources of potassium oxide. Any potassium compound which does not harm the crystallization process is suitable here. Non-limiting examples include oxides, hydroxides, nitrates, sulfates, halides, oxalates, citrates and acetates. Potassium is generally employed in an amount such that the alkali metal / aluminum ratio is at least 1/1, preferably greater than 1/1. Mixtures of potassium with one or more other alkali metals can also be used. The reaction mixture may contain the following components in the indicated amounts (expressed in molar ratios of oxides equal although the actual starting materials may not be oxides): It can be noted that the reaction mixture described above does not include an organic compound that serves as a model to form the zeolite (typically called an "organic model"). In fact, the reaction mixture used in this invention are free organic models. As used herein, the term "free organic model" means that the reaction mixture does not contain, or contains very small amounts of an organic model which is capable of forming the zeolite. If a small amount of a compound that can serve as an organic model for the zeolite is present in the reaction mixture, it must be in a quantity substantially less than that required to form the zeolite. FORMATION OF THE BODIES An advantage of the present invention is that the reaction mixture can be formed in a desired body before the crystallization step, thereby reducing the number of process steps required to prepare catalytic materials containing the zeolite resulting. Prior to the formation of the reaction mixture, it may be necessary to change the liquid content of the reaction mixture, either by drying or by adding more liquid, in order to provide a formable mass which retains its shape. In general for most training methods, water will generally comprise from about 20 percent to about 60 weight percent, and preferably closely • from 30 percent to about 50 percent by weight of the reaction mixture. The reaction mixture is formed in a body, for example, particles. Methods for preparing such bodies are well known in the art, and include, for example, extrusion, spray drying, granulation, • 10 agglomeration and similar l. When the body is in the form of particles, they are preferably of a desired size and shape for the final catalyst, and may be in the form of, for example, extrudates, cylinders, spheres, granules, agglomerates and nuggets. The particles will generally have a cross-sectional diameter between about 1/64 of an inch and about 1/2 of an inch, and preferably between about 1/32 of an inch and 1/4 of an inch, ie, the particles will be a size that will be retained in a 1/64 inch screen, and preferably of 1/32 inch and will pass through a 1/2 inch screen, and preferably through a 1/4 inch screen.

The prepared body of the reaction mixture will contain enough water to retain a desired body. Additional water is not required in the mixture in order to initiate or maintain the crystallization within the reaction mixture formed. Indeed, it may be preferable to remove some of the excess water from the reaction mixture formed prior to crystallization. Conventional methods for drying wet solids may be used to dry the reaction mixture, and may include, for example, drying with air or an inert gas such as nitrogen or helium at temperatures below about 200 ° C. and subatmospheric pressures of about 5 atmospheres of pressure. Clays of natural origin, for example, bentonite, kaolin, montmorillonite, sepiolite and attapulgite, are not required, but can be included in the reaction mixture prior to crystallization to provide a product that has a good resistance to the pressure. Such clays can be used in the natural state as originally extracted or they can be initially subjected to calcination, acid treatment or chemical modification. Microcrystalline cellulose has also been found to improve the physical properties of particles.

CRYSTALLIZATION OF THE ZEOLITE 5 According to the present process, the zeolite is crystallized either within the reaction mixture or within the body produced from the reaction mixture. In each case, the composition of the mixture from which the zeolite is crystallized has the ranges of molar composition • 10 established below. It is preferable that the total volatile content of the reaction mixture during crystallization is in the range of between about 20% by weight and about 60% by weight, and preferably between about 30% by weight and about 60% by weight by weight, based on the weight of the reaction mixture, where the total volatile content is the measurement of the • total volatile liquid, including water, in the reaction mixture. It is an aspect of the present process that no additional liquid is required beyond that required for produce the zeolite L than that required for the crystallization of the zeolite. The crystallization of the zeolite takes place in the absence of an additional external liquid phase, ie, in the absence of a liquid phase separated from the reaction mixture. In general, it is not detrimental to the present processes if some liquid water is present in contact with the reaction mixture during crystallization, and it can be expected that some water may be on the surface of the reaction mixture during crystallization, or that some water can be expelled from the reaction mixture and can be collected in or near the reaction mixture as the reaction progresses. However, it is a purpose of the present invention to provide a method of crystallizing the zeolite in such a way that the amount of water that can be treated and / or discarded following the crystallization is minimized. In this term, the present method provides a method of synthesis of zeolite that does not require more water for crystallization than the sufficient one required to form the zeolite L. The crystallization is conducted at an elevated temperature and usually in an autoclave since the reaction mixture is subject to autogenous pressure until the zeolite crystals are formed. The temperatures during the hydrothermal crystallization steps are typically maintained from about 90 ° C, to about 200 ° C, preferably from about 100 ° C to about 170 ° C. The crystallization is conducted under conditions that • prevent dehydration of the reaction mixture. This can be performed by exposing the reaction mixture to a small amount of water vapor or vapor during crystallization. The crystallization time required to form the crystals will typically be in the range of about 1 hour to • 10 about 10 days, and more often from about 3 hours to about 4 days. Under certain circumstances, crystallization times of less than 24 hours are required to prepare the crystallized material of high crystallinity. In the present method, the crystallized material collected followed by the crystallization step will typically comprise at least about 50% by weight of crystals. The crystallized material contains at least about 80% by weight of crystals, and at level with at least about 90% by weight of crystals, can be prepared using e present method. Before the crystals of zeolite are formed, the crystals can be washed with water and then dried, for example, from 90 ° C to 150 ° C for 8 to 24 hours, the drying step can be carried out at atmospheric and subatmospheric pressures.

CRYSTALS FOR SOWING The zeolite produced by the present process is crystallized on the reaction mixture comprising amorphous reagents. The crystalline material (ie "seeding" crystals of zeolite L) can be added to the mixture before the crystallization step, and the methods for increasing the crystallization of the zeolites by the addition of "seed" crystals are well known. However, the addition of starter crystals is not a requirement of the present process. Indeed, it is an important aspect of the present process that the zeolite can be crystallized within the reaction mixture in the absence of crystals added before the crystallization step.

DESCRIPTION OF ZEOLITE L Zeolite L and its X-ray diffraction patterns are described in U.S. Pat. No. 3,216,789, which is incorporated herein by reference in its entirety. It can be understood that to refer to U.S. Pat. Do not.

No. 3,216,789, it is intended that the identification of the zeolite L be resolved on the basis of its X-ray diffraction patterns. The present invention includes the preparation of the zeolite without consideration of its silica / alumina molar ratio. In this way, the reference to U.S. Pat. No. 3,216,789 is not constructed as a limitation of the present invention for the preparation of the zeolite L having the molar proportions of silica / alumina described in this patent. It is the crystal structure, as identified by the X-ray diffraction model, which establishes the identity of the zeolite L. The zeolite L is characterized by rings of 12 one-dimensional members that have pores of 7.1A. it is generally, but not necessarily, obtained in the form of potassium. Its X-ray diffraction (for the total potassium form) is provided in Table I below. In Table I, d is the distance between two lattice planes, and I / I0 is "the proportion expressed in percent, of the intensity of any given line (I) a to the intensity of the most intense line (lo). lines only considered are those with I / lo greater than 10. Surely the distances as well as the relative intensities can be subject to small variations according to the product analyzed.

Such variations do not indicate a change in structure but are suitable for the replacement of certain cations or for a deviation of the silica / alumina ratio. • TABLE 1 The zeolite produced by the present invention typically has a silica / alumina molar ratio of from about 5 to about 7, preferably from about 5.5 to about 7.0.

ZEOLITE CRYSTALLITE SIZE Typically, zeolite crystals are less than 10 microns in diameter as determined by the Electron Search Microscope.Since then small crystals are deble for certain catalytic applications, crystallization conditions can be custom made to produce zeolite crystals with diameters less than 10 micron. The crystal size of the zeolite can be determined by, for example, grinding the formed particles to separate the individual crystals. High resolution electron micrographs of the separated crystals can then be prepared, after the average size of the individual zeolite crystals can be determined by reference of standard length calibrations. An average crystal size can then be computed in several well-known ways, which include: Average number _ Where n, is the number of zeolite crystals where the minimum lengths fall over an LS interval. For purposes of this invention, the average crystal size differs from some manufacturing terms "zeolite particle size", later the average sizes of all particles, including both individual crystals and polycrystalline agglomerates, in the zeolite powder produced. Typically, the zeolite crystals are less than 10 microns in diameter as determined by the Electron Search Microscope. Since small crystals are desirable for certain catalytic applications, the crystallization conditions can be custom-made by, for example, reducing the crystallization temperature, by increasing the aluminum content in the reaction mixture, and / or by reducing the the water content in the reaction mixture or the particles formed before crystallization, to produce zeolite crystals with diameters less than 10 micron.

POST-TREATMENT OF ZEOLITE A crystallized material containing zeolite crystals is prepared in the process as described • previously. The zeolite can be used as synthesized 5 or can be heat treated (calcined). It may be desirable to partially remove the potassium cation by an ion exchange and replace it with hydrogen, ammonium, or any desired metal ion including other alkali metal cations. It is important, however, that no • All alkali metal is removed or replaced, as this may cause the L zeolite to fall apart. Likewise, zeolite L should not be evaporated. The zeolite can be used in intimate combination with hydrogenated components, such as tungsten, vanadium, molybdenum, Rhenium, nickel, cobalt, chromium, manganese, or a noble metal, such as palladium or platinum, for these applications where a function of hydrogenation / dehydrogenation is desired. Typical replacement cations may include metal cations, for example, rare earth metals, Group IA, Group IIA and Group VIII, as well as their mixtures. Of the replacement metal cations, the cations of metals such as rare earths, Mn, Ba, Sr, Ca, Mg, Cs, Rb, Zn, Ga, Cd, Pt, Pd, Ni, Co, Ti, Al, Sn, Faith, and Co are particularly preferred. Hydrogen, ammonium, and metal components can be exchanged in the zeolite. The zeolite can also be impregnated with the • metals, or metals can be intimately mixed with the zeolite using standard methods known in the art. The metals can be clogged in the glass lattice by having the desired metals present as ions in the reaction mixture where the zeolite is prepared. • 10 Typical ion exchange techniques involve contacting the synthetic zeolite with a solution containing a cation salt or desired replacement cations. While a wide variety of salts can be employed, chlorides and other halides, nitrates, and sulphates are particularly preferred. Representative ion exchange techniques are described in a wide variety of patents including U.S. patents. 3,140,251; 3,14,0,249 and 3,140,253. the ion exchange can take place either before or after the zeolite is calcined.

The contact followed with the salt solution of the desired replacement cation, the zeolite is typically washed with water and dried at temperatures in the range of 65 ° C to about 315 ° C. After washing, the zeolite can be calcined in air or inert gas at temperatures in the range of about 200 ° C to about 820 ° C for periods of time in the range of 1 48 hours, or more, to produce a catalytically active product especially useful in hydrocarbon conversion processes. Despite the cations present in the synthesized form of the zeolite, the spatial arrangement of the atoms forming the basic crystal lattice of the zeolite remnants are essentially not charged. He • 10 exchange of cations has a small, if any, effect on the lattice structures of the zeolite. The zeolite can be used in a catalyst, without additional form, if the reaction mixture has been formed in a body that is of a size and shape desired for the final catalyst. Alternatively, the zeolite can be composed of other materials resistant to • temperatures and other conditions employed in organic conversion processes, using techniques such as spray drying extrusion and the like. Such matrix materials includes active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica and metal oxides. It can then naturally occur or be in the form of gelatinous precipitates, sols, or gels, which include mixtures of silica and metal oxides. The use of an active material in conjunction with the synthetic zeolite, that is, combined with this, tends to improve the conversion and selectivity of the catalyst in certain organic conversion processes. The inactive materials can suitably serve as diluents for controlling the amount of conversion in a given process so that the products can be obtained economically without using other means to control the speed of the reaction. Frequently, zeolite materials have been incorporated into clays of natural origin, for example, bentonite and kaolin. These materials, that is, clays, oxides, etc. they work, partly as links for the catalyst. It is desirable to provide a catalyst that has good pressure resistance, because in the refining of petroleum the catalyst is often subject to rough handling. This tends to pass the catalyst down into the powders causing problems in the process. The clays of natural origin which can be compounded with the synthetic zeolite of this invention include the families of montmorolithite and kaolin, the families including the sub-bentonites and kaolins-commonly known as Dixie, McNamee, the clays of Giorgia and Florida u others where the constituent • Main mineral is haloisite, kaolinite, dickite, 5 nacrite, or anauxite. Fibrous clays such as sepolite and attapulgite can be used as supports. Said clays can be used in the raw state as originally extracted or can be initially provided by calcination, acid treatment or ^ 10 chemical modification. In addition to the above materials, the zeolite prepared by the present method can be composed of porous matrix materials and mixtures of matrix materials such as silica, alumina, titania, magnesia, Silica-alumina, silica-magnesia, silica-zirconia, silica-tories, silica-berilia, silica-titania, titania-zirconia as well as tertiary cmposicones such as silica-alumina- toria, silica-alumina-zirconia, silica-alumina- magnesia and silica-magnesia-zirconia. The matrix can be in the form co-gel. The zeolite can also be composed of other zeolites such as synthetic and natural faujosites (for example X and Y), and heroinites. They can be compounded with purely synthetic zeolites such as those from the ZSM, SSZ, KU, FU, and UN series. The combination of the > Zeolites can also be composed in a matrix Porous inorganic F. The zeolite prepared in the present invention is useful in hydrocarbon conversion reactions. Hydrocarbon conversion reactions are catalytic and chemical processes where the carbon-containing compounds are loaded in different compounds that contain F 10 carbon. Examples of the hydrocarbon conversion reactions include the aromatization of Ce paraffins to benzene products and reformed C6 to Cg hydrocarbons to increase their octane. The zeolite can be used to prepare a reformed catalyst as described in U.S. Patent No. 4,104,320, published August 1, 1978 for Bernard et al., And U.S. Pat. No. 4,634,518 published on January 6, 1978 for Buss et al. both of which are incorporated herein by reference in their entirety. EXAMPLE 1 150 grams of silica (Hi-Sil 233, a hydrated silica manufactured by PPG) is placed in a Baker-Perkins mixer. 40 grams of NaA102 are added to the mixer and the two are mixed for 10 minutes. Then 75 grams of a 50% aqueous solution of KOH is slowly added to the • mixer and mix continuously for about 3 hours. 5 Deionized water (180 grams) is then slowly added to the mixer to form a paste-like mixture. Heat (about 60-66 ° C) is applied to the mix to dry it lightly and make an extrudable. The mixture is extruded through a 1/12 punch • 10 inches and the extuidos are divided into four parts (A, B, C and D). Parts A and B contain 50% volatiles, and parts C and D are air dried with 43% volatiles. The molar compositions of the extrudates are as follows: Si02 / Al203 = 10 15 (Na20 + 'K20) / Si02 = 0.25 K20 / (Na20 + K20) = 0.59 OH "/ Si02 = 0.29 The ratio of H20 / Si02 is 5.0 for parts A and B and 3.8 for parts C and D. 20 Each of parts A, B, C and D are placed in their own one-quarter Teflon bottle with a hole in the cover, and each bottle is sealed in an autoclave which contains 12 cc of water outside the bottles to prevent drying of the samples when they are heated (especially small samples in large large autoclaves) At the end of the crystallization, there is still close • of 12 cc of water outside the bottles, so that the consumption of this water is negligible. The bottles containing parts A and C are then heated to 110 ° C, for four days, and the bottles containing parts B and D are heated to 150 ° C for four days. The resulting extrudates are washed with water deionized, filtered, dried in a vacuum oven at 120 ° C throughout the night. The extrudates are analyzed by X-ray diffraction and determined to contain no L zeolite with other crystalline phases. The percentage of crystals, when compared to a reference of 100% L zeolite are shown in Table II.

• Table II EXAMPLE 2 150 grams of Hi-Sil 233 are placed in a Baker-Perkins mixer. To this is added 30 grams of NaA102 and 7 • grams of NaN0 and the resulting mixture is mixed for about 5 of 10 minutes. To this is added slowly 75 grams of an aqueous solution of KOH and this mixture is mixed for 3 hours. Then, 100 grams of deionized water are slowly added to pass the mixture to a paste. The mixture is then heated to 66 ° C to dry the mixture to • 10 return it to an extrudable form. The mixture is extruded through a 1/12 inch die. A portion of the extrudate is dried with air for 46% volatiles. The molar composition of the extruded portion is as follows: Si02 / Al203 = 13 15 - (Na20-K20) / Si02 = 0.24 K20 / (Na20 + K20) = 0.61 OH ~ / Si02 = 0.29 H20 / SiO2 = 4.2 The extruded is placed in a Teflon bottle of a quart in a stainless steel autoclave and heated to 150 ° C for four days and at a pressure autogenous. The extrudate is washed with water adjusted to pH 12 using an aqueous KOH solution, filtered, and dried overnight in a vacuum oven at 120 ° C. The extrudate is finally calcined in air at 593 ° C for six hours. The extrudate is analyzed by x-ray diffraction and is found to contain the zeolite L as only the zeolite phase.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the one that is clear from the present description of the invention. Having described the invention as above, the content of the following is claimed as property: fifteen twenty

Claims (26)

1. CLAIMS 1. A method for the preparation of crystalline zeolite L, said method is characterized in that it comprises: • (a) the preparation of a self-supporting reaction mixture comprising at least one active source of silica, at least one active source of alumina and a source of hydroxide in amounts sufficient to produce the zeolite L, and sufficient water to produce the zeolite L, wherein the reaction mixture has a molar proportion of • 10 OHVSi02 from 0.20 to 0.40 and (b) heating said reaction mixture to a temperature of about 100 ° C. at about 200 ° C. under conditions "of crystallization and in the absence of an additional external liquid phase for a sufficient time for 15 form the crystals of zeolite L.
2. 2. The method according to claim 1 characterized in that said reaction mixture has a molar ratio of water / silica during crystallization of not greater than about 6.
3. 3. The method according to claim 2 characterized in that said reaction mixture during crystallization has a molar ratio of water / silica of between about 2 to about 5.
4. 4. The method according to claim 1 characterized in that said reaction mixture has the following ranges of molar composition: H.H
5. 5. The method according to claim 4 characterized in that said reaction mixture has the 10 following ranges of molar composition:
6. 6. The method according to claim 1 characterized in that the molar ratio of silica / alumina is from about 5 to about 10. •
7. 7. The method according to claim 6, characterized in that the molar ratio of silica / alumina is from about 5.5 to about 7.
8. 8. The method according to claim 1 • characterized in that said reaction mixture further comprises at least one active source of a Group VIII metal.
9. 9. The method according to claim 8 characterized in that said Group VIII metal is selected from platinum, palladium and a combination thereof.
10. 10. The method according to claim 1 characterized in that the molar ratio in the product of the zeolite is from about 5 to about 7.
11. 11. The method according to claim 1 characterized in that the molar ratio in the product of the zeolite is from about 5.5 to about 7.0. •
12. 12. The method according to claim 1, characterized in that the reaction mixture is extrudable and capable of retaining a body.
13. 13. A method for the preparation of zeolite • Crystalline L, said method is characterized in that it comprises: (a) the preparation of a self-supporting reaction mixture comprising at least one active source of silica, at least one active source of alumina and a source of 15 hydroxide in amounts sufficient to produce the zeolite L, and sufficient water to produce the zeolite L, wherein the reaction mixture has a molar ratio of OH "/ SiO2 from 0.20 to 0.40 and (b) the formation of said reaction mixture in a body; 20 and (c) heating said reaction mixture to a temperature of about 90 ° C. at about 200 ° C. under crystallization conditions and in the absence of an additional external liquid phase for a sufficient time to form the crystals of zeolite L.
14. 14. The method according to claim 13 characterized in that said reaction mixture has a molar ratio of water / silica during crystallization of not greater than about 6.
15. 15. The method according to claim 14 characterized in that said reaction mixture during crystallization has a molar ratio of water / silica of between about 2 to about 5.
16. 16. The method according to claim 13 characterized in that said reaction mixture has the following ranges of molar composition:
17. 17. The method according to claim 16 characterized in that said reaction mixture has the following ranges of molar composition: • # 5
18. 18. The method according to claim 13, characterized in that the molar ratio of silica / alumina is from about 5 to about 7.
19. 19. The method according to claim 18 characterized in that the molar ratio of silica / alumina is from about 5.5 to about 7.
20. 20. The method according to claim 13, characterized in that said reaction mixture further comprises at least one active source of a Group VIII metal.
21. 21. The method according to claim 20 characterized in that said Group VIII metal is selected from platinum, palladium and a combination of the • same.
22. 22. The method according to claim 13 characterized in that the crystalline zeolite formed is a cylindrical or spherical particle having a cross sectional diameter of between 1/64 of an inch and about 1/2 • 10 inch.
23. 23. The method according to claim 22 characterized in that the crystalline zeolite formed is a cylindrical or spherical particle having a diameter of 15 cross section between 1/32 inch and about 1/4 inch.
24. 24. The method according to claim 13 characterized in that the molar ratio in the product of the zeolite is from about 5 to about 7.
25. 25. The method according to claim 13 characterized in that the molar ratio in the product of the zeolite is from about 5.5 to about 7.0. •
26. 26. The method according to claim 13 characterized in that the reaction mixture is extrudable and capable of retaining a body. 10 fifteen twenty