WO2015126236A1

WO2015126236A1 - Method for obtaining a composite aluminosilicate material containing alumina and nanozeolite

Info

Publication number: WO2015126236A1
Application number: PCT/MX2015/000034
Authority: WO
Inventors: Sergio FUENTES MOYADO; Andrey Efimov; Vitalii PETRANOVSKII
Original assignee: Universidad Nacional Autónoma de México
Priority date: 2014-02-18
Filing date: 2015-03-18
Publication date: 2015-08-27
Also published as: MX2014001908A; MX366920B

Abstract

The invention relates to a method for producing a composite aluminosilicate material containing alumina and zeolite. The composite is obtained by means of hydrothermal zeolite synthesis in a macroheterogeneous system in the presence of alumina, which serves as both a reaction component and a support for the resulting zeolite. In the case of the zeolite faujasite (Y) the material obtained is characterised in that it contains a high proportion of zeolite, retaining the large volume of mesopores in the hierarchical porosity of the composite, and nanozeolite crystals that have a high SiO₂/Al₂O₃ ratio.

Description

METHOD OF OBTAINING A COMPOSITE ALUMINOSILICATE MATERIAL CONTAINING ALUMIN AND NANOZEOLITE

FIELD OF THE INVENTION

The present invention relates to composite zeolite-alumina materials and the process for obtaining them, and more particularly, is linked to a process for the production of an aluminosilicate composite material containing alumina and zeolite which is obtained by means of the hydrothermal synthesis of zeolite in a macro-heterogeneous system in the presence of alumina, which simultaneously serves as a reaction component and as a support for the resulting zeolite.

BACKGROUND OF THE INVENTION

The aluminosilicate material composed of the alumina-grown zeolite is prepared from a mixture of reagents for the synthesis of zeolite, to which gamma-alumina powder is added. Subsequently, an in-situ hydrothermal crystallization of the zeolite is performed.

The process for the preparation of different aluminosilicate composite materials with a variety of zeolites can be modified by changing the composition of the reactant mixture and the conditions for synthesis.

The zeolites belong to a family of crystalline aluminosilicates, whose structure is a regular network of channels and micropores with a cross-section of 0.3-1.0 nm, depending on the type of zeolite. With a high adsorption capacity, zeolites also show selectivity, which is determined by the size and identical shape of the pores. The "molecular sieve" effect is used in adsorption, separation and catalysis. Although the zeolites have been used recently As matrices for the creation of new materials (photoelectronics, sensors, etc.), catalysis remains the most important area of application of zeolites. More than 40% of the catalysts in the modern chemical industry are zeolites, mainly in the processes of purification, oil cracking and organic synthesis.

The success of zeolite applications is also based on their properties, such as the ion exchange capacity, acidity and stability of the crystalline structure. The structure of the zeolites is constituted by an aluminosilicate framework, composed of oxygen tetrahedra centered with a Si or Al ion, with the formula Si (AI) 0 ₄ . The presence of trivalent aluminum ions within the tetrahedron AI0 ₄ implies the formation of a negative charge, which is compensated by the presence of cations outside the crystalline network (in most cases by Na ⁺ ), producing a large capacity of ion exchange In some cases, a proton form of the zeolites can be prepared, which have, in addition to the Lewis-type acid centers, Bronsted-type acid centers. Depending on the type of structure and composition of the zeolite (the proportion of silicon and aluminum) the acidity strength can vary significantly. The properties of zeolite, including redox, can be modified by the incorporation of transition metals, as charge-compensating ions, or by the incorporation of complex compounds, as well as directly by the isomorphic substitution of Al in the crystalline lattice. of the zeolite

Zeolites, especially zeolites Y (faujasite family, FAU), as well as type β or ZSM-5, are widely used in catalysts of hydrocracking, fluidized catalytic cracking (FCC), alkylation and transalkylation of aromatic compounds, or catalytic disintegration because they have a large internal surface (microporosity), with a uniform and complex system of channels, high adsorption capacity, high thermal and hydrothermal stability, and pronounced selectivity in catalysis as can be seen in publications A. Corma, Chem. Rev. 97 (1997) 2373; A. Corma, Chem. Rev. 95 (1995) 559 and ME Davis, Nature

417 (2002) 813.

For the catalytic cracking process, zeolite Y is one of the main active ingredients in the catalyst. This is mainly due to its properties, such as the large area provided by the channels and pores with a diameter of 7.4 A, the presence of strong Bronsted acid centers (in its H ⁺ form), good thermal stability, and low cost.

The relatively small and uniform micropores present in zeolites such as Y, beta, ZSM-5, greatly limit the transfer of mass in catalysis, which affects their performance. In particular, the large molecules of the reagents cannot come into contact with the active centers in these small micropores [4-6]. Therefore, the presence exclusively of microscopic pores ≤1.5 nm is a limiting factor for the efficacy of zeolite-based catalysts, (especially for cracking conditions (FCC)), set forth in articles P. Kortunov, et. al., J. Am. Chem. Soc. 127 (2005) 13055-13059 and J. García-Martínez, e. al., Chem. Commun. 48 (2012) 11841-11843.

For certain industrial catalytic applications (cracking of catalytic oil, hydrocracking, alkylating alkynes and aromatic compounds, hydroisomerization, etc.) it has been shown that the presence of mesopores in the zeolite crystals (used as catalyst or catalyst support) is necessary to facilitate reagents access to active centers, reducing steric and diffusion limitations, typical of microporous materials (M. Tromp, et.al. 190 (2000) 209-214 and S. van Don, et. al. 204 (2001) 272-280.

To prepare zeolites with high mesoporosity, or with the so-called "hierarchical" porosity, the template method set forth in X. Meng, et.al., Nano Today 4 (2009) 292-301 is used.

An attractive method for developing mesoporosity in a synthesized zeolite is the use of porous carbon or nanotubes or carbon fibers by introduction to the gel for the synthesis exposed in /. Schmidt, et.al., Chem. Mater. 13 (2001) 4416-4418; Y. Tao, et. al., J. Phys. Chem. B 109 (2005) 194-199; and, A. H. Janssen, et. al., Micropor. Mesopor. Mater. 65 (2003) 59-75.

Recently, mesoporous zeolites with good crystallinity were successfully prepared by using a mesometric scale template during the synthesis of K. Egeblad, et. al., Chem. Mater. 20 (2008) 946; and J. Pérez-Ramírez, et.al., Chem. Soc. Rev. 37 2008) 2530.

These include mesoscale templates such as cationic polymers and organosilanes. Mesoporous zeolites exhibit better catalytic properties compared to conventional zeolites as set forth in F.- S. Xiao, et. to the. Chem., Int. Ed. 45 (2006) 3090; S. Liu, et. to the. Coll. Suri. A 318 (2008) 269;

R. Srivastava, et. to the. Chem. Commun. 43 (2006) 4489; and, V.N. Shetti, et. al., J. Catal. 254 (2008) 296.

After combustion of these templates at elevated temperatures, the pores remain in the zeolite matrix. Although a considerable variety of pore systems can be obtained, the procedure is neither simple nor reproducible with precision, and generates problems derived from the crystallinity of zeolites. In addition, due to its high cost, it is doubtful that this method will expand on a large scale (JC Groen, LAA Peffer, JA Moulijn, J. Perez-Ramirez, Chem. Eur. J., 11 (2005) 4983-4994).

Hydrothermal steam treatment and acid leaching of zeolites are common methods to obtain a higher mesoporosity of crystals, for example of zeolite Y, as set forth in US 5,601,798; US 5,069,890; US 5, 112,473; US 4,269,815; RU 2, 127,227; and, RU 2213055.

In many cases, during its preparation, the zeolite undergoes several stages of processing with a view to its stabilization and desalumination. As a result of this process, the zeolite produced has a reduced value of the unit cell constant (at ₀ ) and an increase in the Si / Al ratio. Three kinds of stabilized Y zeolite are known: ultrastable Y zeolite ("USY"), superultrable Y zeolite ("VUSY") and ultrastable super-skimmed Y zeolite ("SDUSY"). These stabilized zeolites, as well as the Y zeolites in their initial form, have a large number of pores with a diameter greater than 2 nm, the so-called "mesopores", typically with a diameter of 2 to 50 nm. A limited volume of mesopores can be a serious disadvantage in the processes in which coke is formed on such catalysts. Examples of these processes are cracking or hydrocracking heavy crudes.

The first product of the synthesis of zeolite Y (simply referred to in the text Y) shows mesopores of volume <at 0.05 cm ³ / g. In USY type materials, <0.17 cm ³ / g; in VUSY type materials, <0.22 cm ³ / g and in SDUSY type materials, <0.25 cm ³ / g. A synthesis method of USY, for example, described in US Patent 5,069,890 of 1991, consists of a calcination of zeolite Y, previously misaligned with steam at high temperatures for a long period, usually 16 to 24 hours. Since the zeolites and desaluminadas are prepared by simple or multiple steam calcination, to obtain a product with a slightly larger volume of secondary pores, steam calcination is required at least twice. It is observed that after this processing the ratio Si0 ₂ / Al ₂ 0 _{3 is increased} .

In another method, in US Pat. No. 5,112,473, which comprises an acid treatment of the skimmed Y zeolite with values of a ₀ = 24.3-24.5A, a small increase similar to the previous one in the volume of the secondary pores is reported.

However, the method does not allow a substantial increase in said pores.

It is important to mention that steam and acid treatments can lead to loss of crystallinity and significantly reduce the surface area available for reagents and the volume of micropores. This as a result of the removal of aluminum atoms from the zeolite network, which causes their destruction. Very often, these procedures also result in unwanted precipitation of material within the micro- and mesopores (S. Mintova, et. Al. Chem., Int.

Ed. 38 (1999) 3201-3204).

The above has stimulated the development of other methods of obtaining the mesoporous zeolitic material. The method proposed here is through the direct synthesis of zeolite crystallites in alumina. An alternative method for eliminating the limitations of diffusion in the microporosity of zeolites is the use of nanoscale zeolite crystals. Normally, the crystal size of synthetic zeolites is a few you love The reduction of the size of the crystals in orders of magnitude (up to 100 nm or less) results in a very significant reduction of the mean free path of the reagent molecules within the crystal. At the same time it leads to a substantial increase in the external surface of the crystals, which in some cases plays a particular role in the catalytic process, due to the presence in it of multiple active acid sites (for example, network defects, surface hydroxyl groups and oxo groups).

Several research groups have developed the synthesis conditions that produce small zeolite crystals, as is the case described in the publications: L. Tosheva, et. al., Chem. Mater. 17 (2005) 2494-2513; S. Mintova, et. to the. Chem., Int. Ed. 38 (1999) 3201-3204; Y. C. Kim, et. al., J. Por. Mater. 16 (2008) 299-306; O. Larlus, et. to the. Micropor. Mesopor. Mater. 96 (2006) 405-412; and, Holmberg, et. to the. Micropor. Mesopor. Mater. 59 (2003) 13-28. The variables that affect the size of the crystal of Y, are the temperature, the aging time, the alkalinity and the water content as can be read in the previously mentioned articles S. Mintova, et. to the. Chem., Int. Ed. 38 (1999) 3201-3204 and O. Larlus, S. Mintova, T. Bein, Micropor. Mesopor. Mater. 96 (2006) 405-412.

Zeolite nano-crystals are usually synthesized through hydrothermal processes that use transparent aluminosilicate solutions, commonly in the presence of organic additives as templates. The nano-crystalline faujasite zeolite (FAU) has been synthesized using tetramethylammonium (TMA) as a template. Said synthesis procedures are set forth in the articles: S. Mintova, et. al., Chem., Int. Ed. 38 (1999) 3201-3204; O. Larlus, S. Mintova et. al., Micropor. Mesopor. Mater. 96 (2006) 405-412; BJ Schoeman et. to the. Zeolites 14 (1994) 110; NB Castagnola and PK Dutta, J. Phys. Chem. B, 102 (1998) 1696; G. Zhu, et. to the. Chem. Mater. 10 (1998) 1483; and S. Mintova and V. Valtchev, Stud. Surf. Sci. Catal. 125 (1999) 141. Silicalite zeolites (purely siliceous form of ZSM-5), ZSM-5, and Y have been synthesized with discrete crystal sizes of tens of nanometers, as described in the ME Davis literature, Nature 417 (2002) 813.

Synthetic methods employ different molecules as templates, such as tetrapropylammonium hydroxide (TPAOH) for silicalite and ZSM-5, and tetramethylammonium hydroxide (TMAOH) for zeolite Y. The TMA template, applied for the synthesis of Y, can be used. also for the growth of zeolite A.

The template acts as the structure's directing agent and is subsequently removed (postsynthesis) by high temperature calcination, in the air or in pure oxygen. Crystallization conditions are carefully controlled so that nucleation is favored over crystal growth. This is generally achieved through low temperatures of synthesis. On the other hand, low temperatures also slow down the two processes, nucleation and crystal growth, and, therefore, the synthesis time is prolonged and the yields are low.

All synthesis conditions have to be precisely controlled in order to obtain single phase crystals of FAU. In addition, calcination to eliminate templates can cause irreversible aggregation of the nano-crystals, forming larger solid particles.

For example, in N. Taufiqurrahmi, A. Rahman Mohamed, S. Bhatia. IOP Conf. Series: Materials Science and Engineering 17 (2011) 012030. Conference on Advanced Materials and Nanotechnology (CAMAN 2009), 3-5 November 2009, Kuala Lumpur, Malaysia The preparation of the transparent solution for the synthesis of zeolite nanocrystals And the method described by Mintova et al. Chem., Int. Ed. 38 (1999) 3201-3204 and Larlus, et. to the. Micropor. Mesopor. Mater. 96 (2006) 405-412.

A solution of 0.05 N NaOH was diluted with deionized water. After that, a solution of tetramethylammonium hydroxide and aluminum isopropoxide was added, in that order, and stirred vigorously until the solution became clear. Tetraethylorthosilicate was added dropwise to the clear solution. This final mixture was aged for 3 days under vigorous stirring at room temperature. The final molar composition was: 0.72 (TMA) ₂ 0: 0.0094 Na ₂ 0: 0.29 Al ₂ 0 ₃ : 1 Si0 ₂ : 108.82 H ₂ 0.

The crystallization of the zeolite is carried out in a stainless steel autoclave coated with Teflon. After being filled with the transparent solution prepared, the autoclave is completely sealed and heated to 100 ° C. The crystallization time is 6 days. The solid product is recovered by centrifugation, washed several times with distilled water, dried overnight at 80 ° C and calcined in air at 550 ° C for 8 h, to burn the organic template. Unfortunately, the use of organic templates in the form of hydroxides, for example, tetramethylammonium hydroxide (TMAOH), tetraethylammonium (TEAOH), tetrabutylammonium (TBAOH) or tetrapropylammonium (TPAOH), makes the synthesis of colloidal zeolites a very expensive process . On the other hand, the crystalline yield of nanometer-sized zeolites is typically low (O. Larlus, et. Al. Micropor. Mesopor. Mater. 96 (2006) 405-412. For these reasons, the production of nano-sized zeolites without organic templates and, at the same time, with high production performance is a challenge for both scientific and practical reasons.

There are examples of the development of new synthesis routes of ultrafine FAU zeolites without organic additives. Article f-Z Zhan, MA White, KN Robertson, TS Cameron, M. Gharghouri, Chem. Commun., 37 (2001) 1176-1177. It presents an efficient synthesis, free of organic NaX zeolite additives with particle sizes in the range of 20-100 nm. Hydrothermal synthesis was carried out on a stirrer with a temperature controller. Aluminosilicate gel was prepared by mixing freshly prepared aluminate and silicate solutions in the molar ratio 5.5 Na ₂ 0: 1.0 Al ₂ 0 ₃ : 4.0 Si0 ₂ : 190 H ₂ 0. The NaAI0 ₂ was freshly prepared from AI (OH) ₃ and NaOH. The SM-30 solution of colloidal silica (Aldrich), silica fume (Sigma), and TEOS (tetraethyl orthosilicate, Aldrich) were chosen as the silicate sources, without a significant difference observed in the final particle size.

Hydrothermal crystallization was carried out at 60 ° C for 2-4 days on a stirrer with a rotation speed of 250 rpm. In a control experiment, larger FAU zeolite particle sizes were synthesized with exactly the same aluminosilicate gel composition, but hydrothermal crystallization was carried out at 90 ° C for 2 days, without stirring.

The significant decrease in the particle size of NaX-micro and NaX-nano indicates that low crystallization temperatures and conditions of intense agitation are key factors in the control of the size of the zeolite crystals obtained, since together they accelerate the nucleation process and reduce the growth rates of the crystals. By controlling the crystallization temperature, stirring time and silicate source, taking into account the size of its particles, several samples of NaX zeolite with average particle size from 20 nm to 1 miera were successfully synthesized.

Article S. Sang, Z. Liu, P. Tian, Z. Liu, L Qu,. Y. Zhang. Mater. Lett. 60 (2006) 1131-1133 proposes a two-stage variable temperature program for the synthesis of NaY zeolite, producing small uniform crystals, without adding templates, structure-agent director, and without planting crystals or other additives.

All syntheses were carried out according to the following gel composition: 10Na ₂ O: 1.0AI ₂ O ₃ : 15 Si0 ₂ : 300H ₂ O (molar ratio). The initial precursor was prepared by mixing the required amounts of aluminum isopropoxide, sodium hydroxide, colloidal silica and distilled water, and then transferred to an autoclave. Crystallization controlled by a two-stage variable temperature program was carried out at 313 K for 24 h, and subsequently, at 333 K for 48 h.

The two-stage variable temperature program promotes the synthesis of NaY zeolite. The particle size distribution of the synthesized sample is 0.12 ~ 0.85 microns. The lower temperature in the initial stage is favorable for rapid nucleation of NaY zeolite with insignificant crystal growth, and the subsequent higher temperature is beneficial for crystal growth.

To compare with the NaY variable temperature synthesis, the isothermal synthesis of the same zeolite was performed. Crystallization at 393 K induces the formation of zeolite P instead of zeolite Y. When the temperature was lowered to 313 K, only an amorphous solid was produced. An investigation described in W. Bo, M. Hongzhu. Micropor. Mesopor. Mater. 25 (1998) 131-136 was carried out to determine the effects of time and temperature of aging and crystallization on the synthesis of micronized NaY zeolite. The gels were prepared by adding a solution of sodium silicate to an initial solution of aluminosilicate, stirring until a clear mixture formed. Next, aluminum sulfate and sodium aluminate solutions were added in sequence. After stirring for 1 h, the gels with the composition Na ₂ 0: Al ₂ 0 ₃ : Si0 ₂ : H ₂ 0 = 3.01: 1.00: 7.50-10.0: 200 were aged at fixed temperature and time, and then crystallized at 100 ° C

It was found that the crystallization rate and the composition of the crystalline products depend largely on the aging time and the temperature. Compared to the non-aged sample, the average particle size of the aged products decreased from 2.8 to 0.25 m and the general particle distribution decreased from the range 0.5-5 μηι to 0.05-0.8 μητι.

In many cases, the desired balance between the activity of the acid sites and the characteristics of the catalyst surface is achieved through the use of composite materials. In the case of zeolite, the composite material may be a mixture of this with other oxides. In particular, they may be mixtures of zeolite with alumina and / or silica. The latter are also widely used independently as inert, or active substrates, when the main components of a catalyst are transition metal compounds, somehow attached to the support. A catalyst formed by a combination of all these elements (aluminum oxide and (or) silicon, together with zeolite, other transition metal compounds) has a multifunctional nature and has both acid-base and redox activity; furthermore, it shows the inherent properties of sorption and molecular sieve, thus having a certain specific and selective activity.

The most common method of producing a compound composed of oxide and zeolite is by a mechanical mixture of the components, for example, in powder form. To obtain a homogeneous product, a preliminary grinding is preferably applied, or some other method of homogenizing the dispersion of the components. Next, the minimum amount of water necessary to add a consistency composition required for the subsequent extrusion, granulation, tabletting or other process formation process, followed by drying and annealing, is added to the dry mixture. Completing this process, it is considered that the porous zeolites and laminar oxides have enough adsorbed water.

The zeolite phase can be modified in one way or another (by cation content), both before and after the preparation of the compound and its formation.

Also, the microsphere preparation technique has been widely applied, in which the rounded shape and approximately equal size of the particles are achieved simultaneously with spray drying.

In patents RU 2362623 and US 6,762,143, a process for preparing a composite material consisting of a zeolite and an amorphous oxide (alumina or silica) is described. A hydrotreatment catalyst with zeolite and high mesoporosity has been described in Patent RU 2362623. The invention of this patent relates to a bifunctional catalyst having the functions of hydrogenation and acid. This method it forms a composite material that incorporates a zeolite into a non-crystalline inorganic oxide, with mesopores randomly interconnected with each other; In addition, the introduction into this composite material of at least one metal having a hydrogenating function produces a catalyst for the conversion of hydrocarbons.

For the introduction of zeolite into a porous inorganic oxide, preferred technology is described in patents RU 2362623 and US 6,762,143. An aqueous suspension is created by mixing a preformed and / or pretreated zeolite with water. Then, the suspension is mixed with an inorganic oxide or a chemical precursor of inorganic oxide, and at least one template organic compound, to form a mixture, the template is removed by extraction or decomposed by calcination in the last stage, to obtain a compound containing the zeolite incorporated in a non-crystalline and porous inorganic oxide. One method of preparing an amorphous porous inorganic oxide is to use complex compounds, such as, for example, silitranos, aluminatranos, titanatranos and especially trietanolamine compounds, which can be used as chemical precursors of porous and non-crystalline inorganic oxides. Therefore, it is clear that in these patents the preformed and / or pre-prepared zeolite is introduced into the composite material, and does not undergo any further modification. The porosity of the composite material is provided by the action of organic agents, such as glycols, in the amorphous oxide component. Through this method that reports a content of the zeolite in the composite material of about 95%, it is clear that the amount of mesopores formed exclusively by modification of only the amorphous oxide is insignificant. These observations make a fundamental difference with the method proposed in our patent application to obtain the compound. Our method proposes the synthesis of nanometric zeolite as a component of the composite material. It is carried out directly in the presence and partly by the aluminum oxide as a reactant, without having to use a template or a chelator, which makes the elimination by some method of these agents unnecessary and significantly facilitates the synthesis procedure.

The results described in several publications and patent applications indicate the possibility of a deep interaction between the oxide phase and the zeolite, which is not limited to adsorption phenomena on the interface surface.

For example, US 4,468,475 investigated the influence of hydrothermal treatment on the possibility of zeolite activation with a high Si / Al ratio in its alumina mixture. Activation is understood as an increase in acidity, determined by the "alpha" parameter. This parameter indicates the activity of the catalyst for cracking n-hexane in relation to the standard catalyst, which contains 10% alumina and 90% silica, with a first order rate constant for the conversion of n-hexane per unit of catalyst volume under the given conditions (538 ⁰ C) of k = 0.016 sec ^"1. The applied method of evaluation is described in JN M \ a \ ea, et. al., J. Catal. 6 (1966) 278 -287.

Hydrothermal treatment can be carried out in the presence of various amounts of water at different elevated temperatures in the range of 80 to 370 ° C, preferably at 130-170 ° C, for several tens of hours. As a result of this treatment, the composite material obtains a strong increase in cracking activity (5-40 times of the "alpha" parameter). The effect is explained by an increase in the acidity of the zeolite phase, due to the increase in the amount of aluminum in its trellis, which was confirmed by NMR. This increase leads to a greater number of acid sites in the H ⁺ form. The latter apparently is a consequence of the diffusion of the aluminum atoms of the alumina phase into the zeolite phase during the activation process. The effect was much more pronounced when the oxide was used in its hydrated form, α-phase (boehmite, AIO (OH)), and was also evident for less soluble compounds, such as gamma-alumina.

Although the mechanism of such transfer of aluminum between phases has not been accurately described, the fact that it has been confirmed several times, publication C. D. Chang, et. to the. J. Chem. Soc, Faraday Trans. 81 (1985) 2215-2224 indicates that alumina cannot be considered as an "inert" component of the composite.

A possible process of alumina action as a reactant, responsible for the aluminization of the zeolite, is the transfer of aluminum from the alumina phase in some form of hydrated species to the zeolite, during hydrothermal treatment, whereby aluminum is incorporates in place of the structural defects of the zeolitic network deficient in aluminum.

It can be assumed that a similar process is possible, and even more likely, when a germ of the zeolite phase, full of structural defects by definition, plays the role of the aluminum-deficient network. Alternatively, this same role is played by the gel shell with aluminum deficiency and excess silicon. Despite the low solubility of γ-ΑΙ ₂ 0 ₃ , it has a definite and finite value. Studies of the dissolution kinetics of γ-ΑΙ ₂ 0 ₃ in solutions in a pH range between 3 and 1 1 showed that up to 3% is in the dissolved state, forming some of its different possible species, both in the acidic conditions as in alkaline ones (F. Roelofs, W. Vogelsberger. J. Coll. Interf. Sci. 303 (2006) 450-459).

In addition, the most important thing is that the surface regeneration of γ-ΑΙ ₂ 0 ₃ is observed at a pH> 4.5. The bayerite phase AI (OH) _{3 appears} , which is naturally associated with the surface oxide layer. When this phase comes into contact with the solution, a fundamental reconstruction process of the structure occurs because tetrahedral aluminum disappears.

The interaction effect of the alumina phase with the zeolite results in the incorporation of additional aluminum in the crystalline lattice, which decreases its Si / Al ratio and increases its acidity. This is not always desirable, because low acidity is often required at the stage of applying a composite material as a catalyst. For example, in US Patent 5,500, 109, a technique is developed to minimize this effect on zeolite crystals by reducing the amount of defects associated with silanol groups, by means of a controlled pretreatment.

Therefore, the possibility of interaction between the phases in the case of hydrothermal conditions throughout all stages of the synthesis of the zeolite and alumina compound cannot be ignored. This should be considered and used in the preparation of materials composed of an oxide and zeolite. Of course, what type of aluminum oxide (or hydroxide), of its numerous existing phases, should be considered in each particular case, given that its structure, composition and physicochemical properties differ greatly. It should be noted that in US Patent 4,468,475 and in other sources the interaction of the zeolite with aluminum oxides is discussed, as well as the modifications of the zeolite crystals that already exist in the material. In contrast, in the present application, the preparation of a zeolite composite material based on the oxide is based on the interaction between the alumina phase with that of the sun and / or the germs of the zeolite phase. This transformation of the alumina phase not only leads to a change in the content of aluminum in the zeolite, but to the crystallization of the zeolite on the surface of the alumina, by transferring the required amount of aluminum from the alumina.

None of the documents of the state of the art suggest or motivate a person with expertise and average knowledge in the field to carry out a method of obtaining a composite of aluminosilicate that is carried out at low temperatures and no reagents are used. organic, or other materials, a method of obtaining a aluminosilicate compound containing alumina and nanozeolite that allows a great uniformity of the distribution of the zeolite and alumina phases is not disclosed prior to the present application; as well as the synthesis of zeolite crystals of nanometric size; and favors the "coalescence" between the zeolite and the alumina phase.

The present invention provides composite zeolite-alumina materials and the process for preparing them. The aluminosilicate composite material containing alumina and zeolite is obtained by means of the hydrothermal synthesis of zeolite in a macro-heterogeneous system in the presence of alumina, which serves at the same time as a reaction component and as a support for the resulting zeolite. As a result of the above, it has been sought to eliminate the inconveniences presented by the methods of synthesis and processes of the prior art, developing a method of obtaining an aluminosilicate composite material containing alumina and nanozeolite

OBJECTS OF THE INVENTION

Taking into account the implications of the prior art, it is an object of the present invention to provide a method of obtaining an aluminosilicate composite material containing alumina and nanozeolite.

It is also another object of the present invention to provide a method of obtaining an aluminosilicate composite material that is carried out at low temperatures and no organic reagents or other materials are used in order to minimize the size of the zeolites; or get the meso (macro) pores.

It is a further object of the present invention to provide a method of obtaining an aluminosilicate composite material that allows a great uniformity of the distribution of the zeolite and alumina phases; as well as the synthesis of zeolite crystals of nanometric size; and favors the "coalescence" between the zeolite and the alumina phase.

It is still a further object of the present invention to provide a method of obtaining an aluminosilicate composite material that allows obtaining the single phase of Y in the composite material; or by varying, under other conditions, the growth of other forms of zeolite, particularly KS01, in the composite. It is a further object of the present invention to provide a method of obtaining an aluminosilicate composite material, the following properties of which can be adjusted: the selected phase zeolite crystals with nanometric size, the hierarchical porosity (a combination of micro and mesopores), and acidity, that is, the Si / Al ratio.

It is even more an object of the present invention to provide a method of obtaining an aluminosilicate composite material, which consists of a hydrothermal method in a heterogeneous system, which consists of a mixture of aqueous solutions (aluminosilicate sol-gel), and solid alumina.

BRIEF DESCRIPTION OF THE FIGURES

The novel aspects that are considered characteristic of the present invention will be established with particularity in the appended claims. However, some modalities, characteristics and some objects and advantages thereof, will be better understood in the detailed description, when read in relation to the attached drawings, in which:

Figure 1 shows a Scanning Microscopy (SEM) image of the composite material obtained.

Figure 2 shows a graph showing the X-ray powder diffraction patterns of the composite material obtained, the graph shows Na Y + γΑΙ ₂ 0 ₃ (arrows)

Figure 3 shows Image of Transmission Microscopy (TEM) of the composite material obtained, the image shows Na Y with white arrows, and γΑΙ ₂ 0 ₃ with black arrows.

Figure 4 shows a Transmission Microscopy (TEM) image of the composite material obtained. Figure 5 shows a graph showing the adsorption-desorption isotherms of N ₂ of the composite material obtained.

Figure 6 shows a graph showing the distribution of pore sizes (adsorption-desorption data of N ₂ ) of the composite material obtained.

Figure 7 shows a Scanning Microscopy (SEM) image of the product obtained.

Figure 8 shows a graph showing the X-ray powder diffraction patterns of the product obtained. The image shows γ-ΑΙ ₂ 0 ₃ in gray arrows; Y (FAU) in dotted line arrows; and KS01 in black arrows.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method of obtaining an aluminosilicate composite material containing alumina and nanozeolite. The essence of the invention is the synthesis of a composite aluminosilicate material consisting of zeolite and alumina, and whose following properties can be adjusted: the selected phase zeolite crystals with nanometric size, the hierarchical porosity (a combination of micro and mesopores) , and acidity, that is, the Si / Al ratio.

The synthesis of the zeolite and alumina compound is carried out by the following hydrothermal method in a heterogeneous system. The alumina mentioned may be in poorly soluble form, for example, gamma, kappa, etc., preferably gamma-alumina; The mentioned method consists of the following steps: a) Prepare an aluminosilicate solution (sol), by slowly adding an aluminate solution containing crystals of aluminum sulfate hydrate AI ₂ (S0 ₄ ) ₃ -16 H ₂ 0 , H ₂ 0 distilled, and NaOH, to a silicate solution containing colloidal solution of silicon oxide and NaOH. b) Stir vigorously the aluminosilicate solution obtained in the previous stage for 1 hour to obtain a transparent sun.

c) Stop stirring and store for 85 hours without stirring

d) Gel the solution by slowly adding an aqueous solution of H ₂ S0 ₄

e) Stir vigorously for 1 hour the gel resulting from stage d) f) Prepare the reactant mixture for the synthesis of the composite material, mixing the gel from stage d) and subjected to stirring in stage e) with γ- powder At ₂ 0 ₃ in vigorous agitation for 2 hours.

g) Keep the mixture obtained in f) at 20 ° C for 18 hours.

h) Heat the resulting mixture of g) in a closed container and keep the temperature for 8 hours,

i) Suspend the mixture in distilled water,

j) Separate the solid phase by filtration

k) Wash and dry the filtrate

The filtrate is dried at temperatures between 110-130 ° C and, if necessary, calcined at temperatures between 350-550 ° C.

I) The resulting product, a composite material in powder form, contains a mixture of zeolite Y, and γ-0 ₂ 0 ₃ .

The aluminosilicate solution (sol-gel) indicated in the described method may contain the known components for the synthesis of zeolites, in particular, for the synthesis of zeolite faujasite, including NaY, with a ratio of principal components, expressed as ratio of alkali metal, silicon and aluminum oxides, from 3-25 / 5-30 / 1, respectively, mainly from 6-10 / 10-20 / 1, with the optimum ratio of 7-9 / 15-17 / 1; The solution (aluminosilicate sol-gel) described is prepared from certain sources of silicon and aluminum, which allow the formation of a homogeneous sol-gel system, which is stable under normal conditions and does not decompose with the precipitation of the solid phase of some aluminosilicate. For this purpose, it is advantageous to use the salts thereof as a source of soluble aluminum, in particular inorganic salts; In the optimal case, the most hydrated aluminum sulfate hydrate crystal. The source of silicon should preferably be some of its liquid forms, such as the alkali silicate solution (soluble glass or sodium silicate) and, optimally, the colloidal solutions (soles) of silica.

The optimization of the results of the synthesis, preferably with the use of the reagents mentioned above, is achieved by the sequence of steps of preparation of the solution (sol-gel) in stages: in the first phase, highly alkaline solutions of aluminum sulfate and silicon oxide sol, which mix and homogenize; the composition of the solution (sol) obtained in this stage is expressed by the ratio of oxides Na ₂ 0/15 15 17 17 Si0 _2/1 Al ₂ O ₃ / H ₂ 200 300 0. In the second phase, solution (sun) is stored for aging for a period of a few hours up to 30 days, preferably 5-8 days, at temperatures below the temperature that will be applied in the subsequent synthesis, in particular between 4-60 ° C, preferably between 18-25 ° C. In the gelling step by gradual addition of acid, preferably sulfuric acid, to obtain the corresponding to the optimum ratio of components composition specified above: 7-9 Na ₂ 0 / Si0 15-17 _2/1 Al ₂ 0 ₃ / 400-500 H ₂ 0 / 10-12 Na ₂ S0 ₄ .

The heterogeneous system for the synthesis of the composite material is prepared by mixing aluminosilicate (the sol solution, or gel), preferably the gel as described with the appropriate amount of solid aluminum oxide, preferably gamma-alumina, preferably in powder form, with Active mechanical agitation or other method to achieve maximum uniformity of the distribution of solid alumina particles in the gel volume. The optimization of the synthesis result is achieved thanks to the storage (with continuous stirring or not) of the phase obtained above, for a period of several hours to several days, preferably 15-30 hours, at temperatures below the subsequent synthesis temperature, in particular at room temperature (18 -25 ° C).

The relationship between the weight of the aluminosilicate solution (sol gel) and the solid aluminum oxide in a heterogeneous synthesis mixture can vary widely if the conditions for a uniform distribution are guaranteed, which provides the mutual interaction of the particles of the solid phase with the liquid phase; the limits of this relationship are between the amount of solution (gel) corresponding to the conditions of complete wetting, and, on the other hand, that which coincides with the complete alumina solution during hydrothermal synthesis. Optimization of the result of the synthesis of the composite material, in particular, the type of zeolite and the size of its crystals, is achieved with a nanoscale gamma-alumina and zeolite NaY composition with a ratio between the weight of aluminosilicate gel and solid alumina within the range of 5-30 to 1, preferably 10-20 to 1.

The active (high temperature) stage of the hydrothermal synthesis of the composite material is characterized by the crystallization of the zeolite on the surface of the solid alumina, accompanied by the partial dissolution of the latter and its consumption as an additional source of aluminum in addition to the gel. The active stage can be carried out at temperatures between 60-90 ° C without autoclave, or higher when an autoclave is used, for a period of several hours to several days, preferably 6 to 48 hours, the optimum period being 7- 10 hours for the gamma-alumina and zeolite nano NaY compound;

To achieve the desired result in the hydrothermal synthesis of zeolites, that is, the predominant type of zeolite and the purity of its crystalline phase and / or the control of the size of the crystals, the preparation of aluminosilicate gel (sol) is used in stages. The first stage begins with the preparation of a preformed seed gel (seed gel, ZSDA "zeolite structure-directing agent", "zeolite structure directing agent"), which is one of the components of the final gel used in the stage of crystallization at elevated temperature. This method is distinguished from others to prepare the zeolite from the gel, such as the use of seed crystals in the synthesis, and the use of a cation and / or templates (structure directing agent) that contribute to stabilization. of elements of the aluminosilicate structure during the early stages of appearance of the solid phase. In the proposed method, the seed gel does not contain templates and the organic compounds are removed from the synthesis process.

The desired effect of this stage of the method proposed here is achieved by the ratio of the components of the seed gel, which promotes nucleation, but at the same time inhibits crystallization, that is, the growth of crystals.

Typically, the composition of the seed gels has high alkalinity and a relatively higher silica / alumina ratio than the final gel in which the crystallization of the zeolite is achieved.

Thus, for the growth of a zeolite Y, a composition from 15 to 17 of Na ₂ 0: 14 to 16 Si0 ₂ : Al ₂ 0 ₃ : 285-357 H ₂ 0 was used for the seed gel, while for the gel Finally, a composition of 3 to 6 Na ₂ 0: 8 to 12 Si0 ₂ : Al ₂ 0 ₃ : 120 to 200 H ₂ 0 was used. The starting materials were silicate and sodium aluminate.

In, the precursor gel was prepared in two stages: first, the preparation of ZSDA and, second, the preparation of the gel in general. ZSDA with a molar ratio of 16Na ₂ O / 16SiO ₂ / 1AI ₂ O ₃ / 210H ₂ O was prepared by adding a mixture of aluminum sulfate-18-hydrate, granules of sodium hydroxide and deionized water, to a mixture from silica sol and sodium hydroxide. Finally, an appropriate amount of sulfuric acid (99%, Dalian Chemical Reagent Plant) diluted in deionized water was added to the ZSDA, under vigorous stirring to form the final gel with a molar ratio of 7.8Na ₂ 0 / AI ₂ 0 ₃ / 16SiO ₂ / 400H ₂ O.

One way to reduce the size of the zeolite crystals is the addition of salts to the reaction mixture (synthesis gel), especially sodium salts. The effect is attributed to the fact that hydrated ions, particularly Na ⁺ cations, are known as "the structuring agents" (structure directing agents) in the formation of a self-sustaining crystalline structure of zeolite, that is, those elements ( centers), around which the fragments of the crystalline structure of the aluminosilicate are born, which is the same as nuclei of the zeolite phase. Therefore, the number of nuclei and the rate of nucleation predominate over the growth rate of the crystals, which leads to a decrease in their average size. In the absence of electrolyte inputs, alkali cations play the role of nucleation centers. However, the increase in the ionic bottom of the gel and the additional sodium cations can be achieved by using as an aluminum source an aluminum salt, in particular, hydrated aluminum sulfate. Alkaline cations that are initially introduced into the sun remain in the system after partial neutralization and gelation with a mineral acid.

The increase in ionic content can also help overcome the repulsion in the microheterogeneous system between aluminate and silicate particles, which in an alkaline medium have the same sign on surface charges, due to the violation of their double layer electrical, which also contributes to the formation of zeolite nuclei in the aluminosilicate phase. This is more pronounced in the case of synthesis in a macro-heterogeneous system, for example, in a system in which one of the sources is the solid phase of aluminum oxide. The increase in ionic content can lead to the aggregation of submicron zeolites, with each other, as with the present or residual alumina phase. This type of effect can be considered beneficial as noted. Under these agglomeration conditions, the resulting particles (of a few microns) retain the typical advantageous properties of the submicro- and nano-crystals of the zeolites, such as increased diffusion and accelerated ion exchange kinetics. Simultaneously, advantages are obtained for the use of these agglomerates in the industrial catalytic processes associated with their relatively large size and solidity. An important element of the methodology is the aging of the gel

(sun) of seed. Generally the aging of the gel comprises the period between the mixture of reagents to form a phase of the gel and the application of high temperatures to begin its recrystallization and form the zeolite or another phase. Aging always takes place at relatively low temperatures compared to the crystallization temperature.

In the case of step synthesis, for each intermediate gel, for example, for the seed gel, the aging period ends at the moment when the aged gel is mixed with other components to prepare a subsequent or final gel and perform thus the synthesis of the desired product. In the aging stage, the gel restructuring processes occur, including the nucleation of the crystalline phases. Therefore, the highest energy barrier, associated with the appropriate conditions to form the crystals within the actual time intervals, is not reached under the established aging conditions, and, therefore, the nucleation process in certain measure is separated from the crystal growth process.

The aging conditions of gels, such as temperature, time, mixing conditions, other conditions being equal, determine not only the performance of the crystalline product, but also its type, morphology and crystal size.

In general, aging is considered:

- Increases the number of germ nuclei and, subsequently, the nucleation rate of the precursor phase of the zeolite;

- Reduces the induction period and the duration of crystallization;

- Increase the population of crystals (crystalline product yield);

- Reduce the size of the crystals.

It has also been established that in certain cases of faujasite-type zeolite synthesis, insufficient or excessive aging of the final gel leads to the crystallization of other phases and other types of zeolites (sodalite, chabazite, analcime, gismondin). Therefore, it is required to optimize the aging conditions for each gel (sol), including intermediate compositions (for example, seed gel), which allows to achieve the purity of the zeolite and minimize the size of the crystals. The process stage associated with the aging of the mixture of aluminosilicate gel and solid alumina (preferably in powder form), at temperatures relatively lower than the crystallization temperature of the zeolite phase, favors the preferential nucleation of the zeolite in the surface of alumina particles, which provides a more efficient formation of the zeolite phase in the form of numerous nanometric crystals fused directly to the surface of the alumina phase.

In addition, the growth of zeolite crystals on the surface of the alumina is not only due to the recrystallization of the gel skeleton, but also to the consumption of aluminum from the alumina during its partial dissolution, when it interacts with the liquid phase of the silicate rich gel, and the recrystallization of the predetermined zeolite, whose nuclei appeared during the previous nucleation process. The high silica content in the gel promotes this process. In addition, the higher silicon content in the gel promotes the synthesis of a zeolite with a high modulus (Si / Al ratio), which is desirable in many cases, and often one of the objectives to be obtained. In particular in the synthesis of zeolite Y, the high modulus induces an increased and reinforced thermal and hydrothermal stability of such zeolites.

EXAMPLES

The present invention will be better understood from the following examples, which are presented for illustrative purposes only to allow full understanding of the preferred embodiments of the present invention, without implying that there are no other non-illustrated modalities that may be implemented based on the detailed description previously made. The following examples are illustrative of the properties, capabilities and scope of the invention, but are not limiting of its true scope. As an example of the application and performance of the method of obtaining an aluminosilicate composite material containing alumina and nanozeolite already described, the following data and experimental results are described, this in order to provide the necessary elements to carry out the invention, more They are not limiting the scope of it:

The following examples illustrate the present invention; they represent embodiments thereof, without limiting it to these examples.

Example 1.

(1) An aluminate solution, A, is prepared containing 3.95 g of crystals of aluminum sulfate hydrate AI ₂ (S0 ₄ ) ₃ -16 H ₂ 0, 12.34 g of distilled H ₂ 0, and 3.16 g of NaOH .

(2) A silicate solution, B, is prepared containing 20.03 g of the colloidal solution of silicon oxide (Ludox 30, 30% Si0 ₂ by weight) and 6.49 g of NaOH.

(3) A solution of aluminosilicate (sol), C, is prepared by slowly adding solution A to solution B with vigorous stirring for 1 hour.

(4) the clear sol is made with composition C 16.3 Na ₂ 0 / Si0 ₂ 16.0 / Al ₂ 0 _3/273 H ₂ 0 / Na ₂ S0 ₄ 3, and stored for 85 hours without stirring.

(5) Sol C is gelled by the slow addition of 22 ml of an aqueous solution of H ₂ S0 ₄ (concentration 2.31 M).

(6) The resulting gel, D, of composition 8.16 Na ₂ O / 16.05 Si0 ₂ / Al ₂ 0 _3/462 H ₂ 0 / Na ₂ S0 ₄ 11.14 stirred vigorously for 1 hour. (7) The reactant mixture is prepared for the synthesis of the composite material, mixing 42.00 g of D gel and 2.00 g of γ-ΑΙ ₂ 0 ₃ powder (SA 6173 Norton Chemical Process Product Corporation) with vigorous stirring for 2 hours.

(8) The mixture is maintained at 20 ° C for 18 hours.

(9) The resulting mixture is heated to 90 ° C in a closed container made of polypropylene and maintained at this temperature for 8 hours.

(10) The product obtained is suspended in excess of distilled water, the solid phase is filtered off through a synthetic membrane using a vacuum pump, washed in the filter until it reaches pH 8 and then the filtrate is dried during 24 hours at 120 ° C.

(11) The resulting product, a powder-shaped composite material, contains a mixture of zeolite Y, and γ-0 ₂ 0 ₃ .

The composite material has been characterized by the following methods:

- X-ray diffraction;

- scanning electron microscopy;

- EDS microanalysis (energy dispersion spectroscopy);

- transmission electron microscopy (TE);

- the N ₂ physical adsorption technique that describes the characteristics of the porosity.

An image obtained by SEM (Figure 1) shows that the product is a combination of pseudo-spherical agglomerated particles with a size of about 200 nm.

According to the EDS analysis, the Si / Al atomic ratio has the value equal to 2.02 in the composite and 2.75 in the zeolite. According to X-ray diffraction, the composite material consists exclusively of zeolite Y (FAU) and γ-ΑΙ ₂ 0 ₃ (Figure 2). There are no other phases. The estimation of the size of the zeolite Y crystals by expanding reflections applying the Scherrer equation gives a value of 45 nm.

The evaluation of the quantitative proportions of the components in the composite material according to the EDS and X-ray diffraction data shows that about 27% of aluminum oxide is in an alumina phase, corresponding approximately to a ratio in weight of γ-ΑΙ ₂ 0 ₃ and zeolite from 1 to 10. Analysis of the images obtained by the TEM (Figures 3 and 4) confirms that the composite particles are agglomerated that have alumina particles in the center that express poor crystallinity , coated with well-formed and densely fused nanoscale zeolite crystals (20-100 nm). The characteristics of the surface and pores of the composite material have been determined by the nitrogen adsorption method.

The type of adsorption-desorption isotherms is characteristic for a material with a hierarchical pore structure, with a developed outer surface, and which has mesopores (Figure 5). Despite the fact that the zeolite phase prevails in the composite material, it is a compound that differs fundamentally from the conventional zeolite sample, for which the surface of the mesopores and external is insignificant. Table 1 shows the data calculated by the BET and t-plot methods in the surface area and the pore volume of the composite material obtained. For comparison, data for a typical sample of the synthesized zeolite Y are shown. Table 1

In particular, the total surface area of the composite material was 372 g / m ² , which gives a value less than that of zeolite, but 2 times greater than the value of the initial total surface area of γ-ΑΙ ₂ 0 ₃ . Although the composite material has a microporous surface smaller than zeolite, this material has mesopore volumes tens of times larger than zeolite.

Example 2

(1) An aluminate solution, A, is prepared containing 5.79 g of crystals of aluminum sulfate hydrate AI ₂ (S0 ₄ ) ₃ -16 H ₂ 0, 15.83 g of distilled H ₂ 0 and 3.16 g NaOH.

(2) 28.90 g of the colloidal solution of silicon oxide (Ludox 30, 30% Si0 ₂ by weight) is taken, it is solution B.

(4) The composition transparent sol C 15.93 Na ₂ 0 / Si0 ₂ 15.79 / Al ₂ 0 _3/269 H ₂ 0 / Na ₂ S0 ₄ 3 is stored for 85 hours without stirring.

(5) The aged C sun is gelled by the slow addition of 35.2 ml of an aqueous solution of H ₂ S0 ₄ (concentration 2.31 M). (6) The resulting gel, D, of composition 7.04 Na ₂ 0 / Si0 ₂ 15.79 / Al ₂ 0 _3/475 H ₂ 0 / Na ₂ S0 ₄ 11.88 stirred vigorously for 1 hour.

(7) The reactant mixture for the synthesis of the composite material is prepared with 16.04 g of D gel and 2.93 g of γ-ΑΙ ₂ 0 ₃ powder (SA 6173 Norton Chemical Process Product Corporation) with vigorous stirring for 2 hours.

(8) The obtained mixture is kept at 20 ° C for 18 hours.

(11) The resulting product, a powder-shaped composite material contains a mixture of zeolite KS01, zeolite Y, and γ-0 ₂ 0 ₃ .

The composite material has been characterized by the following methods:

- X-ray diffraction;

- scanning electron microscopy;

- EDS mycroanalysis (energy dispersion spectroscopy).

An image obtained by SEM (Figure 7) shows that the product is a combination of pseudo-spherical agglomerated particles with a size in the range of 0.5 to 1.0 microns, which in turn are agglomerated of the smallest particles.

According to the EDS analysis, the Si / Al atomic ratio has the value in the composite material of 1.69.

According to the X-ray diffraction, the composite material consists of a predominant amount of zeolite KS01 (described Ref. [66]), of γ-ΑΙ ₂ 0 ₃ and zeolite Y (Figure 8). The estimation of the size of zeolite Y crystals by extension of reflections applying the Scherrer equation gives a value of 15 nm and, therefore, we conclude that the material synthesized by this method has a high content of zeolite Y nanoscale crystals. Although certain embodiments of the invention have been illustrated and described, it should be emphasized that numerous modifications to it, such as different concentrations or inclusion of new active substances, are possible to the present invention but such modifications would not represent a departure from the true scope of the invention. Therefore, the present invention should not be considered as restricted except as set forth in the prior art, as well as by the scope of the appended claims.

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Claims

NEWS OF THE INVENTION CLAIMS

1. - A hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite, characterized in that it comprises the following stages:

a) Prepare an aluminosilicate solution (sol), by slowly adding an aluminate solution to a silicate solution

b) Vigorously shake the aluminosilicate solution obtained in the previous stage to obtain a transparent solution.

c) Stop stirring and store without stirring

d) Gel the solution by slowly adding an aqueous acid solution e) Vigorously shake the gel resulting from step d)

f) Prepare the reactant mixture for the synthesis of the composite material, mixing the gel from stage d) and subjected to stirring in stage e) with γ-powder.

At ₂ 0 ₃ with vigorous stirring.

g) Maintain the mixture obtained in f) at a temperature of 18 °C to 25 °C.

h) Heat the mixture resulting from g) and maintain temperature,

i) Suspend the mixture in distilled water,

j) Separate the solid phase by filtration

k) Wash and dry the filtrate

I) The resulting product, a composite material in powder form, contains a mixture of zeolite Y, and γ-ΑΙ ₂ 0 ₃ .

2. - The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 further characterized in that the aluminate solution contains aluminum sulfate hydrate crystals AI ₂ (S0 ₄ ) ₃ - 16 H ₂ 0, distilled H ₂ 0, and NaOH.

3.- The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 further characterized in that the silicate solution contains colloidal solution of silicon oxide and NaOH.

4 - The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 further characterized in that the alumina can be in a poorly soluble form, selected from the group consisting of gamma, kappa, etc.

5. - The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 4 further characterized in that the alumina is preferably gamma-alumina.

6. - The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite in accordance with claim 1 further characterized in that the aluminosilicate solution obtained in step a) is expressed by the ratio of oxides 15 17 Na ₂ 0/15 17 Si0 ₂ /1 AI ₂ O ₃ /200 300 H ₂ 0.

7 - The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 further characterized in that the aluminosilicate solution in step c) is stored to achieve aging for a period of up to 30 days. .

8.- The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 7 further characterized in that the aluminosilicate solution in step c) is stored to achieve aging for a period of preferably 5 to 8 days

9. - The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 further characterized in that the aqueous acid solution used to gel the aluminosilicate solution in step d) is preferably aqueous acid solution of H ₂ S0 ₄ .

10. - The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 or 9 further characterized in that the gelled aluminosilicate solution of step d) has a component ratio of 7- 9 Na ₂ 0/15-17 Si0 ₂ /1 Al ₂ 0 ₃ /400-500 H ₂ O/10-12 Na ₂ S0 ₄ .

11.- The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 further characterized in that heating the solution in step h) is carried out at temperatures of 60 °C to 90 ° C; in a time interval of 6 to 48 hours.

12.- The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1 further characterized in that heating the solution in step h) is carried out in a time interval preferably from 7 to 10 hours.

13.- The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite in accordance with claim 1 further characterized in that in step k) the filtrate is dried at temperatures between 110-130 °C and, if necessary, it is calcined at temperatures between 350 - 550 °C.

14.- The hydrothermal process for the production of an aluminosilicate composite material containing alumina and zeolite according to claim 1, further characterized in that it allows obtaining uniformity of the distribution of the zeolite and alumina phases, as well as zeolite crystals of nanometer size; and favors the "coalescence" between the zeolite and the alumina phase.