MXPA96005638A - Halide free process for the synthesis of ets - Google Patents

Abstract

The present invention relates to a process for the preparation of ETS-10 molecular sieve, which is characterized in that it comprises preparing a halide-free reaction mixture containing a source of titanium, a source of silica, an alkali metal source and water , said reaction mixture having a composition in terms of molar ratios that are within the following ranges: SiO2 / Ti 2-20, H2O / SiO2 2-200, Mn / SiO2 0.05-10 in which M indicates valence cations n , alkali metal hydroxide derivatives and / or halide-free alkali metal salts, maintain the reaction mixture at a temperature of about 100 ° C to 300 ° C for a period of time ranging from about 1 hour to 40 days to a pH of 8.5 to 12 and recover said ETS- molecular sieve

Description

HALIDE FREE PROCESS FOR THE SYNTHESIS OF ETS-10 DESCRIPTION This invention relates to a novel process for the preparation of ETS-10, which is a large pore crystalline titanium molecular sieve zeolite described and claimed in U.S. 4,853,202. It is also related to a novel form of ETS-10, in which the individual crystals are characterized by a uniform morphology. The present invention eliminates the use of halide reagents, which have previously been employed in the preparation of ETS-10 so that it results in a wide choice with respect to the reaction vessels, as well as the production of a product which It has a uniform crystal size, which is controlled by seeding techniques that use ETS-10 as the seed source. BRIEF DESCRIPTION OF THE DRAWINGS The only Figure containing four scanning electron photomicrographs in two different amplifications of the products obtained from Examples 1 and 2. The present invention is directed towards crystalline titanium molecular sieve zeolites, which have a size of pore of approximately 8 Angstrom units and ~ p * s have a molar ratio of titanium to silica in the range of 2.5 to 25. ETS-10 molecular sieves are described and claimed in the US. 4,853,202, the description of which is incorporated herein by reference and have a crystal structure and an X-ray powder diffraction pattern having the following significant lines: TABLE 1 10 XRD Powder Pattern of ETS-10 (0 -40 ° theta) d-Significant Space (Angs.) I Io 14.7 ± .35 -M 7.20 ± .15 WM 4.41 ± .10 WM 3.60 ± .05 VS 3.28 ± .05 WM 20 In the previous table: VS = 60-100 S = 40-60 M = 20-40 Values previous ones were determined by means of normal techniques. The radiation was the copper doublet of K-alpha, and a scintillation counter spectrometer was used. The peak heights, I, and positions as a function of 2 times theta, where theta is the Bragg angle, were read from the spectrometer chart. From this, the relative intensities, 100 L / I, where IQ is the intensity of the strongest line or peak, and d (obs.), The interplane space in A, which corresponds to the registered lines, were calculated. It should be understood that the X-ray diffraction pattern is characteristic of all species of the ETS compositions. The exchange of ions of sodium ions and potassium ions, with cations, reveals substantially the same pattern with minor changes in interplane space and variation in relative intensity. Other minor variations may occur depending on the silicon to titanium ratio of the particular sample, as well as if it has been subjected to thermal treatment. Several forms of ETS cation exchange have been prepared and their X-ray powder diffraction patterns contain the most significant lines set out in Table 1. The U.S. No. 4,853,202 discloses a method for the preparation of ETS-10, in which corrosive halides, i.e., chloride and / or fluoride reagents, are used. The current commercial methods for synthesis require the use of expensive titanium or Hastelloy® crystallization vessels. Eliminating halides from reagents could allow the synthesis to be conducted in more readily available and less expensive containers, resulting in reduced capital investment. The term "halide-free" as used in the specification and claims, is intended to mean no deliberate addition of halide. However, very small amounts of halide may be present due to the presence of impurity levels in the reagents employed. As noted in column 5, line 20 of the U.S.

No. 4,853,202, the source of titanium oxide is a trivalent compound such as titanium trichloride. In addition, an alkali metal fluoride is usually included in the crystallization mixture, that is, see column 4, line 43, although the patent makes it clear that this is necessary, that is, see Example 6 of the U.S. 4,853,202. The ETS-10 molecular sieves prepared according to the novel process of this invention are crystallized from a reaction mixture containing a titanium source without halide such as titanium sulfate. Other sources of titanium may be used, such as titanium oxysulfate and titanium alkoxides. It is preferred that the titanium be in a tetravalent state as opposed to the trivalent state.

The present invention prepares ETS-10 by forming a reaction mixture containing a source of halide-free titanium, for example, such as titanium sulfate, a source of silica, a source of alkalinity, such as an alkali metal hydroxide and water, having a composition in terms of oxides in moles of relations falling within the following ranges. TABLE 2 Wide Preferred Very Preferred sio2 / ti 2-20 3-10 4-7 H20 / Si02 2-200 5-100 10-50 M2 / Si02 .05-10 .2-5 .5-3 where M indicates the valence cations, n derived from the alkali metal hydroxide and / or halide-free alkali metal salts used to prepare the titanium silicate according to the invention. The reaction mixture is heated to a temperature of about 100 ° C to 300 ° C or more, for a period ranging from about 1 hour to 40 days, or longer. The hydrothermal reaction is carried out until they form crystals and the resulting crystalline product is then separated from the reaction mixture, cooled to room temperature, filtered and washed with water. The reaction mixture can be stirred, although it is not necessary. It has been found that when gels are used, agitation is unnecessary but can be used. When titanium sources are used, which are solid, agitation is beneficial. The preferred temperature range is 150 ° C to 250 ° C for a period ranging from about 1 hour to 4 days. The crystallization is carried out in a continuous or intermittent form under autogenous pressure in an autoclave, static pump reactor or through flow reactor. Following the washing step with water, the crystalline ETS can be dried at temperatures of 15 to 426 ° C (60 ° to 800 ° F) or more for periods of up to 30 hours. The method for preparing ETS compositions comprises the preparation of a reaction mixture consisting of silica sources, titanium source, alkalinity sources such as sodium and / or potassium oxide and water having a molar ratio reagent composition as set forth in Table 2. The silica source includes the majority of the reactive silicon source such as silica, silica hydrosol, silica gel, silicic acid, silicon alkoxides, alkali metal silicates, preferably sodium or potassium, or mixtures of the above. As previously noted, the titanium oxide source is preferably a tetravalent titanium compound such as titanium sulfate. In any case, halides are not used. The source of alkalinity is preferably an aqueous solution of an alkali metal hydroxide, such as sodium hydroxide, which provides a source of alkali metal ions to maintain electrovalent neutrality and control the pH of the reaction mixture within the range from 9.0 to 11.5 ± 0.5. The alkali metal hydroxide serves as a source of sodium oxide, which can also be supplied by means of an aqueous solution of sodium silicate. It is preferred that the crystallization gel mixture contain ETS-10 seeds, which serve to improve the rate of crystallization. The amount of seeds added ranges from about 0.01 to about 150 pounds of seed / 1,000 pounds of gel. The particle size of the seed determines the actual amount added with a larger amount added with seeds with a larger particle size. The crystalline titanium silicate as synthesized, may have its original components replaced by a wide variety of others according to the well-known techniques. Typical replacement components could include hydrogen, ammonium, alkylammonium and arylammonium and metals, including mixtures thereof. The hydrogen form can be prepared, for example, by replacing the original sodium with ammonium or by direct exchange with mineral acid. The composition is then calcined at a temperature of, for example, 537 ° C (1,000 ° F), provoking the evolution of ammonia and hydrogen retention in the composition, that is, hydrogen and / or decationized form. Of the replacement metals, it is preferably according to the metals of Groups II, IV and VIII of the Periodic Table, preferably the rare earth metals. The crystalline titanium silicates are then preferably washed with water and dried at a temperature ranging from 15 ° C to about 426 ° C (60 ° F to about 800 ° F) and then calcined in air or other inert gas at temperatures ranging from 260 ° C to 815 ° C (500 ° F to 1500 ° F) for periods ranging from 1 to 48 hours or more. Regardless of the synthesized form of titanium silicate, the spatial arrangement of atoms, which form the basic crystal lattice structures, remain essentially unchanged through the replacement of sodium or other alkali metal or by the presence in the initial reaction mixture. of metals other than sodium, as determined by means of an X-ray powder diffraction pattern of the resulting titanium silicate. The X-ray diffraction patterns of such products are essentially the same as those set forth in Table 1 above. The crystalline titanium silicates prepared according to the invention are formed in a wide variety of particular sizes. Generally, the particles may be in the form of a powder, a granule, or a molded product such as an extrusion product having a particle size sufficient to pass through a 2-mesh (Tyler) screen and be maintained over a sieve of 400 mesh (Tyler), in cases where the catalyst is molded such as by means of extrusion. The titanium silicate can be extruded before drying or drying or partially dried and then extruded. When used as a catalyst, it is desired to incorporate the new crystalline titanium silicate with another material resistant to the temperatures and other conditions employed in the organic processes. Such materials include active and inactive and synthetic materials and naturally occurring zeolites as well as inorganic materials such as clays, silica and / or metal oxides, the latter may be either occurring naturally or in the form of gelatinous precipitates or gels including mixtures of silica and metal oxides. The use of a material together with the new crystalline titanium silicate, ie, combined with it, which is active, tends to improve the conversion and / or selectivity of the catalyst in certain organic conversion processes. The inactive materials suitably serve as diluents to control the amount of conversion in a given process, that the products can be obtained economically and in an orderly manner without employing other means to control the reaction rate. Normally, crystalline materials have been incorporated into naturally occurring clays, for example, bentonite and kaolin to improve the compressive strength of the catalyst under commercial operating conditions. These materials, ie, clays, oxides, etc., function as binders for the catalyst. It is desirable to provide a catalyst having a good compressive strength, due to an oil refinery, the catalyst is usually subjected to strong handling, which tends to break the catalyst into powder-like materials, which causes problems in the processing. These clay binders have been used for the purpose of improving the compressive strength of the catalyst. Naturally occurring clays that can be composed of the crystalline titanium silicate described herein include the smectite and kaolin families, such families include montmorillonites such as sub-bentonites and the kaolins commonly known as Dixie, McNamee, Ga. and Florida or others in which the main constituent is halloysite, aolinite, dickite, nacrite or anauxite. Such clays can be used in the crude state as originally mined or initially subjected to calcination, acid treatment or chemical modification. In addition to the above materials, the crystalline titanium silicates can be composed of matrix materials such as silica-alumina, silica-magnesia, silica-zirconia, silica-toria, silica-berilis, silica-titania as well as ternary compositions, such as such as silica-alumina-toria, silica-alumina-zirconia, silica-alumina-magnesia and silica-magnesia-zirconia. The matrix can be in the form of a cogel. The relative proportions of the finely divided crystalline metal organosilicate and the organic oxide gel matrix can vary widely with the crystalline organosilicate content, ranging from about 1 to 90 weight percent and more usually in the range of about 2 to about 50 percent by weight of the mixed material. As is known in the art, it is desirable to limit the alkali metal content of materials used for acid catalyzed reactions. This is usually achieved by means of ion exchange with hydrogen ions or their precursors such as ammonium and / or metal cations, such as rare earths. Using the catalyst of this invention, which contains a hydrogenation component, heavy oil waste supplies, cycle supplies and other hydrodegradable charge supplies can be hydrodisintegrated at temperatures between 204 ° C and 440 ° C (400 ° F and 825 ° F). ) using molar ratios of hydrogen to hydrocarbon charge in the range between 2 and 80. The pressure used varies between 0.703 and 175.7 kg / cm2 (10 and 2,500 psig) and the space velocity per hour of liquid between 0.1 and 10. Using the catalyst of this invention for catalytic cracking, cracking supplies with hydrocarbon at a space velocity per hour of liquid between about 0.5 and 50, a temperature between about 287 ° C and 593 ° C (550 ° F and 1100 ° F) can be cracked. ), a pressure between approximately subatmospheric and several hundred atmospheres. Employing a catalytically active form of a member of the zeolite family of this invention which contains a hydrogenation component, reforming supplies can be reformed using a temperature between 371 ° C and 537 ° C (700 ° F and 1000 ° F) . The pressure may be between 7.03 and 70.3 kg / cm2 (100 and 1,000 psig), but is preferably between 14.06 to 49.21 kg / cm2 (200 to 700 psig). The space velocity per hour of liquid is generally between 0.1 and 10, preferably between 0.5 and 4 and the molar ratio of hydrogen to hydrocarbon is generally between 1 and 20, preferably between 4 and 12. The catalyst can also be used for the hydroisomerization of normal paraffins, when provided with a hydrogenation component, for example, platinum. The hydroisomerization is carried out at a temperature between 93 ° C and 371 ° C (200 ° F and 700 ° F), preferably from 148 ° C to 287 ° C (300 ° F to 550 ° F), with a high speed of space per hour of liquid between 0.01 and 2, preferably between 0.25 and 0.50, using hydrogen such that the molar ratio of hydrogen to hydrocarbon is between 1: 1 and 5: 1. Additionally, the catalyst can be used for the isomerization of olefin using temperatures between -1.1 ° C and 260 ° C (30 ° F and 500 ° F). EXAMPLE 1 This example illustrates the actual state of the preparation of the ETS-10 technique. It is taken directly from the pilot scale scale synthesis of ETS-10 for desiccant applications and involves several years of evolution of the methods described in U.S. 4,853,202.

An alkaline slurry was prepared by sequentially adding 174.3 g (384 pounds) of sodium silicate (28.8% Si02, 8.94% Na20), 49 g (108 pounds) of a sodium hydroxide solution (38.9% Na20), 50.8 g (112 pounds) of a solution of potassium fluoride (K20 at 32.4%) and 0.47 g (1.04 pounds) (dry weight) of ETS-10 seeds present as a slurry in 1.8 g (4 pounds) of deionized water. The mixture in the established order is mixed and homogenized. A solution consisting of 38.6 g (232 pounds) of deionized water, 32.9 g (72.6 pounds) of concentrated hydrochloric acid (33.7% HCl) and 36.6 g (85.2 pounds) of a solution of titanium oxychloride (Ti02 al 21.1%, HCl at 35.8%). The sludge and solution were mixed in equal proportions through simultaneous addition to a 5 gallon (18.5 liter) bucket equipped with an overhead shaker at 1700 rpm using a 10.16 cm (4 inch) Cowles high shear blade. ), then pumping to a large support tank. Through mixing, a gel pH of 10.2 ± 0.1 was typically maintained. The final pH of the fully mixed gel was 10.2 + 0.1. The gel is crystallized in a autoclave lined with 370 liters (100 gallons) titanium stirred at 215 ° C for 24 hours. The crystallized product is filtered and washed with deionized water.

The product is recovered and has the following X-ray diffraction data. D Spac I / Imax (Ana.) (%) 14.7552 24.37 7.1931 13.15 6.8268 1.69 4.9275 3.23 4.4055 27.05 4.2535 2.35 3.7318 3.58 3.5990 100.00 3.4461 24.68 3.3435 8.64 3.2735 22.23 3.1337 5.81 2.9811 11.16 2.8107 4.60 2.5372 11.02 2.5178 19.90 2.4612 10.19 2.4251 4.38 2.3550 5.61 The scanning electron micrographs (SEM) are presented in the Figure.

EXAMPLE 2 This example demonstrates this invention. An alkaline solution containing 330 grams of potassium hydroxide (85%) in 3.250 grams of deionized water is prepared. To the solution are added 5.512 grams of sodium silicate (28.8% Si02, 8.94% Na20) and 2,000 grams of a sodium hydroxide solution (38.9% Na20) and the mixture was mixed until a clear solution resulted. An acid solution containing 5,000 grams of deionized water and 4.305 grams of titanium sulfate (9.3% Ti02, 37.8% H2SO4) is prepared and added to the base solution with agitation at 2,500 rpm using a top mixer equipped with a doctor blade. high shear stress. The pH of the gel at this point was 11.0. The pH is reduced to 10.13 using sulfuric acid. Then 10 grams are mixed (dry weight) of ETS-10 seeds in 500 grams of deionized water, in the gel using the same top mixer. The final pH of this gel portion was 10.2 ± 0.1. The gel at this point has a mass of 21.92 kg. A 17.00 kg portion of the gel is separated and 2,000 grams of deionized water are added to this portion and stirred for 10 minutes using the top mixer. This portion of the gel is crystallized in a 18.5 liter (5 gallon) autoclave by shaking at 225 ° C for 24 hours. The crystallized product is filtered and washed with deionized water. The crystalline product is washed and the product is recovered and has the following XRD data. D Spac I / Imax (Ang.) (%) 14.6634 21. .87 11.6459 6, .04 8.8847 1, .91 7.2063 11. .38 6.8202 2, .05 4.9295 3, .32 4.4071 27, .92 3.7376 3, .03 3.6047 100. .00 3.4478 28, .34 3.2780 22, .72 3.1382 7, .43 2.9874 14, .52 2.8890 4, .04 2.8102 5, .80 2.6742 2, .41 2.5397 12, .27 2.5202 20, .14 2.4656 11, .04 2.4261 5.99 2.3554 7.11 2.2738 2.29 Scanning electron micrographs (SEM) are presented in the Figure. As can be seen, the XRD data of the product of Example 1 and Example 2 are substantially identical and both result in the preparation of ETS-10. The scanning electron microscopic images of the product in Examples 1 and 2 demonstrate the dramatic differences in the uniformity of the individual particles between the samples. In the Figure, the left column illustrates the particle size of the ETS-10 crystals of Example 1 at amplifications of 5.03 KX (upper) and 20.4 KX (lower). The column on the right illustrates the particle size of the ETS-10 crystals of Example 2 at amplifications of 5.03 KX (upper) and 20.4 KX (lower). The product of Example 2 contains clear individual crystals of uniform morphology, which are easily processed with substantially no loss during filtration. Uniformity of morphology also implies uniformity of chemical properties, a critical parameter for any application including cyclic desiccation.

The term "uniform morphology" is intended to represent individual blocking crystals of uniform size and shape, wherein any given preparation of crystals is characterized by a narrow unimodal Gaussian distribution with the average crystal size for any given preparation being between 0.1-20 microns in its smallest dimension, for example, as determined by means of microscopic evaluation.

Claims (7)

1. CLAIMS 1. A process for the preparation of ETS-10, which is characterized in that it comprises preparing a halide-free reaction mixture containing a source of titanium, a source of silica, an alkali metal source and water, having a composition in terms of molar ratios that are within the following ranges: Si02 / Ti 2-20 H20 / Si02 2-200 Mn / Si02 0.05-10 in which M indicates valence n cations derived from alkali metal hydroxides and / or halide-free alkali metal salts, which maintain the reaction mixture at a temperature of about 100 ° C to 300 ° C for a period of time ranging from about 1 hour to 40 days at a pH of 8.5 to 12 and recovering the ETS-10.
2. 2. The process according to claim 1, characterized in that the molar ratios fall within the following ranges: Si02 / Ti 3-30 H20 / SiO2 5-100 Mn / SiO2 0.2-5
3. 3. The process according to claim 1, characterized in that ETS-10 has molar ratios that fall within the following ranges: Si02 / Ti 4-7 H20 / Si02 10-50 Mn / Si02 0.5-3
4. 4. The process in accordance with claims 1, 2 or 3, characterized in that the source of titanium is titanium sulfate.
5. 5. The process according to claim 1, 2 or 3, characterized in that M is a mixture of sodium and potassium.
6. 6. The process according to claim 1, 2 or 3, characterized in that the seeds of ETS-10 are added to the reaction mixture.
7. 7. ETS-10 having the X-ray diffraction lines established in Table 1 and characterized by crystals which have a uniform morphology.