PREPARATION OF ZEOLITE BETA

Abstract: This invention relates to a new method for synthesis of zeolite Beta, to the zeolithe Beta product of that new method and to use of said zeolite Beta prepared in accordance herewith as a catalyst for organic compound, e.g. hydrocarbon com­ pound, conversion.

Description: PREPARATION OF ZEOLITE BETA This invention relates to a new method for synthesis of zeolite Beta, to the crystalline silicate product of that new method and to use of that crystalline silicate as a catalyst for organic compound, e.g. hydrocarbon compound, conversion. Crystalline zeolite Beta, which is identified by its x-ray diffraction pattern, and its conventional preparation are disclosed in US-A-3,308,069. According to the invention a method for preparing zeolite Beta comprises forming a reaction mixture containing sources of alkali metal oxide, an oxide of aluminum, an oxide of silicon, dimethylbenzylamine, benzyl halide and water and having a composition, in terms of mole ratios, within the following ranges: Broad Preferred SiO2/A1203 less than 60 to 300 80 to 200 OH-/SiO2 0.09 to 0.37 0.1 to 0.2 H2O/OH- 70 to 200 80 to 170 (R'+R")/(R'+R"+M) 0.2 to 1.0 0.4 to 0.8 wherein R' is dimethylbenzylamine, R" is benzyl halide, e.g. chloride, bromide or iodide, and M is an alkali metal ion, and maintaining the mixture until crystals of the crystalline zeolite Beta are formed. The quantity of OB- is calculated only from the inorganic sources of alkali without any organic base contribution. Thereafter, the crystals are separated from the liquid and recovered. Reaction conditions required consist of heating the foregoing reaction mixture to a temperature of from about 1000C to about 150QC for a period of time of from about 24 hours to about 12W days. A more preferred temperature range is from about 1300C to about 140 C with the amount of time at a temperature in such range being from about 24 hours to about 22 days. The solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water washing. eolite Beta synthesized in accordance with the present method exhibits a wide range of silica/alumina mole ratios and significant catalytic activity for certain conversions of interest, including low pressure hydrocracking, hydroisomerization and dewaxing. The particular effectiveness of the presently required combination of dimethylbenzylamine and benzyl halide, when compared with other directing agents, is believed due to the ability of their reaction product, in aitur to function as a template in the nucleation and growth of zeolite Beta crystals. The reaction product is believed to be the halide salt of dibenzyldimethylammonium. The reaction mixture composition can be prepared from materials which supply the appropriate oxide. Such compositions include aluminates, alumina, silicates, silica hydrosol, silica gel, silicic acid and hydroxides. Each oxide component utilized in the reaction mixture for preparing the zeolite can be supplied by one or more essential reactants and they can be mixed together in any order. For example, any oxide can be supplied by an aqueous solution, sodium hydroxide or by an aqueous solution of a suitable silicate; the organic cation can be supplied by the directing agent compound of that cation, such as, for example, the hydroxide or a salt, e.g. halide, such as chloride, bromide or iodide. The reaction mixture can be prepared either batchwise or continuously. Crystal size and crystallization time will vary with the nature of the reaction mixture employed. The molar ratio of dimethylbenzylamine to benzyl halide should be within the range of 0.3 to 0.6 in the reaction mixture, and preferably about 0.5. The present method for zeolite Beta synthesis is economically desirable when compared to prior art methods, since it avoids costly use of quaternary ammonium compounds. The amine and halide for use herein are less expensive than a quaternary salt. In the reaction mixture required of the present invention, the mole ratios of SiO2/A1203 and OH-/SiO2 are critical, as is the temperature maintained during crystallization. If the SiO2/A1203 mole ratio is above 300 and the OH-/SiO2 mole ratio is below 0.05, a silicate other than zeolite Beta forms as the predominant product. If the crystallization temperature is maintained above 1750C, undesirable side products are formed. The lower temperature requirement is another cost advantage of the present process. Zeolite Beta freshly synthesised in accordance with the invention will usually conform with the formula in terms of mole ratios of oxides and in the anhydrous state: (1 to 25)R20:(0 to 0.8)M2/nO:A12O3:(X)SiO2 wherein N is at least one cation having a valence n, R, usually in excess in the as synthesized composition, is the cation derived from the ia situ reaction product of the dimethylbenzylamine and the benzyl halide reaction mixture components, and X is from greater than about 10 to about 300. The original cations can be replaced, at least in part, by calcination and/or ion exchange with another cation. Thus, the original alkali metal cations are exchanged into a hydrogen or hydrogen ion precursor form or a form in which the original cation has been replaced by a metal of Groups TIA, lilA, IVA, IB, IIB, IIIB, IVB, VIB or VIII of the Periodic Table. Thus, for example, it is contemplated to exchange the original cations with ammonium ions or with hydronium ions. Catalytically active forms of these would include, in particular, hydrogen, rare earth metals, aluminum, metals of Groups II and VIII of the Periodie Table and manganese. The x-ray diffraction pattern of zeolite Beta has the characteristic lines shown in Table 1. TABLE 1 Interplanar d-Spacing (A) Relative Intensity (IiI 11.5 + 0.4 M-S 7.4 + 0.2 W 6.6 + 0.15 W 4.15 + 0.10 W 3.97 i 0.10 VS 3.00 + 0.07 W 2.05 + 0.05 W These values were determined by standard technique. The radiation was the K-alpha doublet of copper, and a diffraction equipped with a scintillation counter and a strip chart pen recorder was used. The peak heights, I, and the positions as a function of two times theta, where theta is the Bragg angle, were read from the spectometer chart. From these, the relative intensities, 100 I/Io where Io is the intensity of the strongest line or peak, and d (obs.), the interplanar spacing in Angstrom units (A) corresponding to the recorded lines, were calculated. In Table 1 the relative intensities are given in terms of the symbols W=weak, M=medium, S=strong and VS=very strong. Ion exchanged forms of the zeolite manifest substantially the same pattern with some minor shifts in interplanar spacing and variation in relative intensity. Other minor variations can occur depending on the silicon to aluminum ratio of the particular sample and its thermal history. While the crystalline silicate of the present invention may be used in a wide variety of organic compound, e.g. hydrocarbon compound, conversion reactions, it is notably useful in the processes of low pressure hydrocracking, hydroisomerization dewaxing and cracking. Other conversion processes for which improved zeolite Beta may be utilized in one or more of its active forms include, for example, hydrocracking and converting light aliphatics to aromatics such as in US-A-3,760,024. Zeolite Beta prepared in accordance herewith can be used either 1n the organic nitrogen-containing and alkali metal containing form, the alkali metal form and hydrogen form op another univalent or multivalent cationic form. It can also be used in intimate combination with a hydrogenating component such as tungsten, vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese, or a noble metal such as platinum or palladium where a hydrogenation-dehydrogenation function is to be performed. Such components can be exchanged into the composition, impregnated therein or physically intimately admixed therewith, for example by, in the case of platinum, treating the zeolite with a platinum metal-containing ion. Suitable platinum compounds for this purpose include chloroplatinic acid, platinous chloride and various compounds containing the platinum amine complex. Combinations of metals and methods for their introduction can also be used. Zeolite Beta, when employed either as an adsorbent or as a catalyst, should be dehydrated at least partially, suitably by heating to a temperature in the range of from about 2000C to about 6000C in an inert atmosphere, such as air, nitrogen, etc. and at atmospheric or subatmospheric pressures for between 1 and 48 hours. Dehydration can also be performed at lower temperature merely by placing the zeolite in a vacuum, but a longer time is required to obtain a particular degree of dehydration. The organic cations of freshly synthesized zeolite Beta can be decomposed by heating to a temperature up to about 5500C for from 1 hours to about 48 hours. As above mentioned, zeolite Beta prepared in accordance herewith can have the original cations associated therewith replaced by a wide variety of other cations according to techniques well known in the art. Typical replacing cations include hydrogen, ammonium and metal cations including mixtures thereof. Of the replacing metallic cations, particular preference is given to cations of metals such as rare earths, Mn, Ca, Mg, Zn, Cd, Pd, Ni, Cu, Ti, Al, Sn, Fe and Co. Typical ion exchange technique would be to contact the synthetic zeolite with a salt of the desired replacing cation or cations. Although a wide variety of salts can be employed, particular preference is given to chlorides, nitrates and sulfates. Catalysts comprising zeolite Beta prepared according to the invention may be formed in a wide variety of particle sizes. Generally speaking, the particles can be in the form of a powder, a granule, or a molded product, such as extrudate having particle size sufficient to pass through a 2 mesh (Tyler) screen and be retained on a 400 mesh (Tyler) screen. In cases where the catalyst is molded, such as by extrusion, the crystalline silicate can be extruded before drying or dried or partially dried and then extruded. In the case of many catalysts it is desirable to composite a zeolite with another material resistant to the temperatures and other conditions employed in certain organic conversion processes. Such matrix materials include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica and/or metal oxides, e.g. alumina and are described in our EP-A-1695. Employing a catalytically active form of the composition of this invention containing a hydrogenation component, reforming stocks can be reformed employing a temperature between 3700C and 540 C. The pressure can be between 100 and 1000 psig (7.9 to 70 bar), but is preferably between 200 and 700 psig (14.8 to 49.3 bar). The liquid hourly space velocity is generally between 0.1 and 10 hr"l, preferably between 0.5 and 4 hr-l and the hydrogen to hydrocarbon mole ratio is generally between 1 and 20, preferably between 4 and 12. The catalyst can also be used for hydroisomerization of normal paraffins, when provided with a hydrogenation component, e.g. platinum. Hydroisomerization is carried out at a temperature between 900C to 3700C, preferably 1400C to 2900C, with a liquid hourly space velocity between 0.01 and 2 hr'l, preferably between 0.25 and 0.50 hr'l, employing hydrogen such that the hydrogen to hydrocarbon mole ratio is between 1 and 5. Additionally, the catalyst can be used for oleo in or aromatics isomerization employing temperatures between OOC and 3700C. The catalyst can also be used for reducing the pour point of gas oils. This process is carried out at a liquid hourly space velocity between about 10 and about 30 hr'l and a temperature between about 4000C and about 5400C. Other reactions which can be accomplished employing the catalyst of this invention containing a metal, e.g. platinum, include hydrogenation-dehydrogenation reactions and desulfurization reactions, oleo in polymerization (oligomerization), and other organic compound conversions such as the conversion of alcohols (e.g. methanol) to hydrocarbons. The following examples illustrate the invention. In the examples, whenever adsorption data are set forth for comparison of sorptive capacities for water, cyclohexane and n-hexane, they were determined as follows: A weighed sample of the calcined adsorbant was contacted with the desired pure adsorbate vapor in an adsorption chamber, evacuated to 1 mm and contacted with 12 mm Hg of water vapor or 20 mm Hg of n-hexane, or cyclohexane vapor, pressures less than the vapor-liquid equilibrium pressure of the respective adsorbate at room temperature. The pressure was kept constant (within about + 0.5 mm) by addition of adsorbate vapor controlled by a monostat during the adsorption period, which did not exceed about 8 hours. As adsorbate was adsorbed by the sorbant material, the decrease in pressure caused the monostat to open a valve which admitted more adsorbate vapor to the chamber to restore the above control pressures. Sorption was complete when the pressure change was not sufficient to activate the monostat. The increase in weight was calculated as the adsorption capacity of the sample in go100 g of calcined adsorbant. EXAMPLEl A solution of 0.42 grams of sodium aluminate (43.3% A1203 and 32.2% Na2O), 2.0 grams NaOH and 20.0 grams of water was added to 90.0 grams of colloidal silica (30% solution). To this was then added 5.7 grams of dimethylbenzylamine and 5.5 grams of benzyl chloride. The total was then thoroughly mixed. The mixture, which had the composition in mole ratios: SiO2/A1203 = 252 OH-/SiO2 = 0.12 H2O/OH- = 84.8 (R'+R")/(R'+R"+Na) = 0.61 wherein R' is dimethylbenzylamine and R" is benzyl chloride, was then allowed to crystallize in a glass-lined stainless steel autoclave at 1250C for 21 days. The crystalline product was separated from the remaining mixture, filtered, washed with water and dried at 1350C. Chemical analysis showed the composition of the crystalline product to be: 10.7 wt.% C 0.90 wt.% N 0.14 wt.% Na 0.83 wt.% A12O3 83.4 wt.% SiO2 86.7 wt.% Ash 171 SiO2/A1203 molar ratio X-ray analysis indicated crystalline zeolite Beta, with a trace of non-Beta crystalline material. A quantity of the product was calcined at 5500C for 16 hours in air, and then tested for sorption properties. The results were: 9.6 wt.% cyclohexane sorbed, 8.1 wt.% n-hexane sorbed, and 11.3 wt.% water sorbed. EXAMPLE 2 A solution of 0.46 grams of sodium aluminate (43.3% A1203 and 32.28 Na20), 2.48 grams NaOH and 161.0 grams of water was added to 36.8 grams of colloidal silica (30% solution). To this was then added 15.5 grams of dimethylbenzylamine and 14.5 grams of benzyl chloride. The total was then thoroughly mixed. The mixture, which had the composition in mole ratios: SiO2/Al2o3 = 92.3 OS¯/SiQ2 = 0.37 2 / ff- = 155 (R'+B"b/(R'+R"+Na) = 0.77 wherein R' is dimethylbenzylamine and RW is benzyl chloride, was then allowed to crystallize in a polypropylene jar under static conditions at 1000C for 35 days. The crystalline product was separated from the remaining mixture, filtered, washed with water and dried at 1350C. Chemical analysis showed the composition of the crystalline product to be: O.ll wt.% Na 1.9 wt.% A1203 72.7 wt.% SiO2 75.3 wt.% Ash 65.1 SiO2/A1203 molar ratio The crystalline product was dried at 1100C in air and subjected to x-ray analysis. Its diffraction pattern conformed with that set forth in Table 1 and indicated 60% crystallinity of the zeolite Beta relative to a reference standard. A quantity of the product was calcined at 5400C for 16 hours in air, and then tested for sorption properties. The results were: 22.4 wt.% cyclohexane sorbed, 17.2 wt.% n-hexane sorbed, and 25.5 wt.% water sorbed. EXAMPLE3 A solution of 0.74 grams of sodium aluminate (43.3% A1203 and 32.2% Na2O), 30 grams NaOH and 116 grams of water was added to 80.0 grams of colloidal silica (30% solution). To this was then added 9.93 grams of dimethylbenzylamine and 9.3 grams of benzyl chloride. The total was then thoroughly mixed. The mixture, which had the composition in mole ratios: SiO2/A12O3 = 127 OH-/SiO2 = 0.22 H20/OH- = 109 (R+R")/(R'+R"+Na) = 0.63 wherein R' is dimethylbenzylamine and R" is benzyl chloride, was then allowed to crystallize in a polypropylene jar under static conditions at 1000C for 115 days. The crystalline product was separated from the remaining mixture, filtered, washed with water and dried at 1350C and submitted for chemical and x-ray diffraction analysis. Chemical analysis showed: 1.3 wt.% A1203 74.9 wt.% SiO2 97.9 SiO2/A1203 molar ratio The x-ray results indicated a 55% crystalline zeolite Beta (relative to standard) with a minor amount of non-Beta crystalline material.

Claims: CLAIMS 1. A method for synthesizing zeolite Beta which comprises preparing a mixture containing sources of alkali metal (M) oxide, an oxide of aluminum, an oxide of silicon, dimethylbenzylamine (R'), benzyl halide (R") and water and having a composition, in terms of mole ratios, within the following ranges: SiO2/A1203 = 60 to 300 OH-/SiO2 = 0.09 to 0.37 H2O/OH- = 70 to 200 (R'+R")/(R'+R"+M) = 0.2 to 1.0 and maintaining the mixture at a temperature of 1000C to 1500C until crystals of the zeolite are formed. 2. The method of claim 1 wherein said mixture has a composition, in terms of mole ratios, as follows: SiO2/A12O3 = 80 to 200 OH-/SiO2 = 0.1 to 0.2 H2O/OH- = 80 to 170 (R'+R")/(R'+R"+M) = 0.4 to 0.8 3. The method of claim 1 or claim 2 wherein said benzyl halide is the chloride, bromide or iodide. 4. Zeolite Beta having the composition, in the anhydrous state, expressed in terms of mole ratios of oxides, as follows: (1 to 25)R20:(0 to 0.8)M2/nO:Al2O3:(X)SiO2 wherein N is at least one alkali metal cation having the valence n, R is a cation derived from the reaction product of dimethylbenzylamine and benzyl halide and X is from 10 to 300. 5. The zeolite of claim 4 wherein M is sodium. 6. A zeolite according to claim 4 wherein the cations n and/or R have been replaced by hydrogen and/or metals of Groups IIA, lilA, IVA, IB, IIB, IIIB, IVB, VIB and/or VIII of the Periodic Table. 7. A. process for catalytic conversion of an organic compound which comprises contacting said compound under conversion conditions with a catalyst comprising zeolite Beta prepared in accordance with any of claims 1 to 3.

Inventors: RUBIN, MAE KOENIG
Applicants: MOBIL OIL CORPORATION
Application year: 1985
Main classification: C01B33
IPC codes: C01B39, C07C1, C10G49, B01J29, C07C67, C07C5, C07C9