JP2011046575A - Method for manufacturing mordenite - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing mordenite by performing a specific treatment under the condition for synthesizing an aluminosilicate, MCM-68. <P>SOLUTION: The mordenite is formed by properly fluidizing raw materials during crystallization in synthesizing the MCM-68. The method for manufacturing mordenite includes heating a mixture while fluidizing it in an autoclave, the mixture being composed of (1) a silica source, (2) a hydroxide or halide of N,N,N',N'-tetraalkylbicyclo[2.2.2]octo-7-ene-2,3:5,6-dipyrrolidinium (wherein, alkyl groups have 4 or less carbon atoms and may be the same or different), (3) a hydroxide of an alkali metal or a hydroxide of an alkaline-earth metal, and (4) water. The method for manufacturing mordenite further includes baking the mordenite as-synthesized. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing mordenite having an MOR structure.

Aluminosilicate MCM-68 is a relatively new zeolite synthesized by Mobil in 2000 (Patent Document 1). This zeolite has a structure in which large pores (12-membered ring pores) and medium pores (10-membered ring pores) intersect three-dimensionally. Since this type of zeolite generally has a large surface area and a large internal space, it is useful as a catalyst in petroleum refining and petrochemical processes, and is expected to be useful as a catalyst using a relatively bulky organic molecule as a substrate.
The manufacturing method of aluminosilicate MCM-68 by Mobil is to heat a gel obtained by mixing a template (template), colloidal silica, potassium hydroxide, aluminum hydroxide and water in an autoclave, and to fire the resulting crystals. It is synthesized by the so-called hydrothermal method.
On the other hand, mordenite, which is a kind of zeolite, has a square columnar skeleton structure, and a gel obtained by mixing a normal template (template), powdered silica, sodium hydroxide, aluminum chloride and water, It is synthesized by a hydrothermal method of heating in an autoclave and firing the resulting crystals (Non-patent Document 1).

Special Table 2002-535227 (International Publication WO00 / 43316)

Microporous and Mesoporous materials 95 (2006) 141-145

  Usually, MCM-68 was synthesized by leaving the autoclave to stand (Comparative Example described later).

However, the present inventors have found that when synthesizing MCM-68, mordenite is produced when the contents are fluidized by rotating the autoclave. Furthermore, it has been found that there is an optimum range for the number of revolutions that mordenite efficiently produces. That is, mordenite can be produced by using the same raw material as the synthesis of MCM-68 and appropriately flowing the raw material during crystallization.
That is, the present invention provides (1) silica source, (2) N, N, N ′, N′-tetraalkylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium. (However, the alkyl group has 4 or less carbon atoms and may be the same or different.) (3) Alkali metal hydroxide or alkaline earth metal hydroxide And (4) a process for preparing mordenite comprising heating the mixture in an autoclave while flowing the mixture, and mordenite comprising further calcining the as-synthesized mordenite. It is a manufacturing method.

The schematic of the synthesizer used in Example 1 is shown. A to D represent the rotation state of the autoclave. 2 is a diagram showing an X-ray diffraction pattern of mordenite obtained in Example 1. FIG. The upper figure is as synthesized and the lower figure is after firing. 1 is a scanning electron micrograph of as-synthesized mordenite obtained in Example 1. FIG. 2 is a diagram showing an X-ray diffraction pattern of a product obtained in Example 2. FIG. A shows the case where the rotational speed of the autoclave is 0 rpm (stationary), B shows the rotational speed of 20 rpm, C shows the rotational speed of 40 rpm, D shows the rotational speed of 60 rpm, and E shows the rotational speed of 80 rpm. It is a figure which shows the conversion rate of the cracking reaction of cumene of Example 3. 6 is a view showing an X-ray diffraction pattern of MCM-68 obtained in Comparative Example 1. FIG. The upper figure is as synthesized and the lower figure is after firing.

The mordenite of the present invention is an aluminosilicate having a structure in which 12- and 8-membered ring channels intersect two-dimensionally. The unit cell (unit cell) is an orthorhombic (rectangular) crystal system having a composition of RnSi48-nAlnO96 (R represents a cation).
Mordenite is given the three letter code “MOR” by the International Zeolite Association Structure Commission (IZA-SC) and has a topology that is uniquely determined by the atomic coordinates and crystallographic parameters shown in Table 1.
Note) Space group Cmcm (No. 63 space group defined by International Union of Crystallography (IUCr)) Lattice constant a = 18.25 Å, b = 20.51 Å, c = 7.50 Å

Hereafter, the manufacturing method of the mordenite of this invention is demonstrated in order.
(A) First, (1) silica source, (2) N, N, N ′, N′-tetraalkylbicyclo [2.2.2] oct-7-ene-2, 3: 5,6- as a template Hydroxides or halides of dipyrrolidinium (wherein the alkyl group has 4 or less carbon atoms and may be the same or different), (3) alkali metal hydroxide or alkaline earth metal water As-synthesized mordenite is synthesized by heating a mixture of the oxide and (4) water in an autoclave while flowing the mixture.

Examples of the silica source used in the present invention include water glass, colloidal silica, fumed silica, silicon alkoxide, and quartz, and preferably fumed silica.
The mold (template) used in the present invention has the following formula:
N, N, N ′, N′-tetraalkylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium represented by the formula: is there.
The alkyl groups in the formula (ie, R ¹ and R ² ) may be the same or different and have 1 to 4 carbon atoms. R ¹ and R ² may each be the same, or all alkyl groups (ie, R ¹ and R ² ) may be the same.
As this alkyl group, for example, CH _3- , CH ₃ CH _2- , CH ₃ CH ₂ CH _2- , (CH ₃ ) ₂ CH-, CH ₃ CH ₂ CH ₂ CH _2- , (CH ₃ ) ₂ CHCH _2- , (CH ₃ CH ₂ (CH ₃ ) CH-, (CH ₃ ) ₃ C- can be mentioned,
This compound (template) may be used as a hydroxide or halide (iodide, bromide, chloride, fluoride).

The alkali metal hydroxide or alkaline earth metal hydroxide used in the present invention is preferably an alkali metal hydroxide, for example, LiOH, NaOH, KOH, CsOH, Mg (OH) ₂ , Ca (OH) _2. , Sr (OH) ₂ or Ba (OH) ₂ , preferably NaOH. In the case of KOH, a purity of 85% or more is used. In other cases, a purity of 95% or more is used, diluted to 5 to 50% with deionized water, or previously diluted.
The water used is preferably high-purity water, for example, ion-exchanged water (deionized water).

  Each of the above components is 10 to 50 mol, more preferably 10 to 30 mol, and alkali metal hydroxide or alkaline earth metal hydroxide 1 to 30 mol, more preferably 100 mol of silica. 10-30 mol and water are used in a proportion of 500-10000 mol, more preferably 2000-7000 mol.

These raw materials are appropriately mixed and stirred to obtain a uniform aqueous reaction raw material composition, and then crystallized under conditions such that the raw material flows.
This produces mordenite.
The conditions for fluidizing the raw material can be created by, for example, a method of continuously changing the direction of the autoclave by rotating the autoclave containing the synthetic gel at a specific rotation speed (Example 2 described later). checking).
Such a preferable rotation condition is to rotate the autoclave at 10 to 60 rpm, preferably 20 to 30 rpm.
The heating temperature at this time is 120-200 degreeC, More preferably, it is 150-170 degreeC. The heating time is generally 120 to 400 hours, preferably 150 to 200 hours.

The as-synthesized mordenite obtained in this step is represented by the following composition formula.
_{R n Al n Si 48-n} O 96
(In the formula, n represents about 4 to 5.)
Si / Al is about 8.5-12.
R represents one obtained by removing the charge from the cation portion (R ²⁺ ) of the template.
The X-ray diffraction data includes the following values. (Peak with an intensity ratio of 10% or more)
2θ = 6.60 ± 0.10, 8.76 ± 0.10, 9.84 ± 0.05, 13.64 ± 0.05, 15.40 ± 0.10, 19.76 ± 0.10, 22.40 ± 0.10, 23.32 ± 0.10, 25.84 ± 0.10, 26.40 ± 0.10, 27.84 ± 0.10, 31.08 ± 0.10, 35. 84 ± 0.10

(B) Firing step The crystalline silicate is fired after being taken out of the autoclave. This firing is usually performed using a muffle furnace or a tubular furnace in an atmosphere of O ₂ : N ₂ = 0: 100 to 100: 0, preferably 20:80 to 30:70, and 0.1 to 100 ml / min. The flow is carried out for 1 to 12 hours at a flow rate. The temperature is 500 to 800 ° C, preferably 600 to 700 ° C.
Mordenite obtained in this step is represented by the following composition formula.
_{H n Al n Si 48-n} O 96 ( wherein, n represents 4-5.)
This crystalline porous silicate has the MOR structure described above and has a skeletal topology specified by the space group and atomic coordinates in Table 1 above.

The mordenite X-ray diffraction data after the firing treatment includes the following values. (Peak with an intensity ratio of 10% or more)
2θ = 6.60 ± 0.10, 8.86 ± 0.10, 9.88 ± 0.05, 13.56 ± 0.05, 15.40 ± 0.10, 19.76 ± 0.10, 22.36 ± 0.10, 23.32 ± 0.10, 25.80 ± 0.10, 26.40 ± 0.10, 27.84 ± 0.10, 31.08 ± 0.10, 35. 84 ± 0.10
The mordenite after firing is a fine particle having a length L in the major axis (c-axis) direction of 80 to 100 nm, and a length L in the major axis (c-axis) direction and a length in the minor axis (a- or b-axis) direction. The ratio of D (aspect ratio: L / D) is 1.0 to 2.0.

The following examples illustrate the invention but are not intended to limit the invention.
In this example, X-ray diffraction was measured under the following conditions.
Equipment used: MX-Labo powder X-ray analyzer manufactured by MAC Science Co., Ltd. X-ray source: CuKα = 1.5405A, applied voltage: 40 kV, tube current: 20 mA
Measuring range: 2θ = 2.040 ~ 52.000deg
Scan speed: 2.000 deg./min, Sampling interval: 0.040 deg.
Diverging slit: 1.00 deg, Scattering slit: 1.00 deg, Receiving slit: 0.30 mm
Using vertical goniometer and monochromator Measurement method Continuous method, normal method

Production Example 1
In this synthesis example, the template used in the examples described later was synthesized.
First, N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-tetracarboxydiimide was synthesized as shown in the following formula.
Bicyclo [2.2.2] oct-7-ene-2,3: 5,6-tetracarboxylic dianhydride (manufactured by Aldrich) 15.7 g (63 mmol) to ethylamine (Kanto Chemical) (70 wt% in water) 100 ml (1.26 mol) was added and stirred at room temperature for 2 hours. Distilled water (46 ml) was added thereto, and the mixture was stirred at 70 ° C. for 24 hours and then at 100 ° C. for 20 hours. After allowing to cool, concentrated hydrochloric acid (11 ml) was slowly added dropwise until the pH reached about 2. This was subjected to suction filtration, washed with distilled water (500 ml), and the solid obtained was dried. The yield of the product (N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-tetracarboxydiimide) was 17.1 g (90% yield).

Next, N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidine was synthesized.
6.2 g (164 mmol) of lithium aluminum hydride (LiAlH ₄ , manufactured by Wako Pure Chemical Industries, Ltd.) was added to a 1000 ml two-necked flask in an N ₂ atmosphere, and 300 ml of tetrahydrofuran (THF) was added while stirring, and stirring was started. The diimide body 16.0 g (53 mmol) obtained above was added little by little here, and it washed in with THF (240 ml). Thereafter, the mixture was stirred for 68 hours under reflux. After allowing to cool, distilled water (6.2 g), 15 wt% NaOH (6.2 g), and distilled water (18.7 g) were added slowly in order at intervals of about 30 minutes with sufficient stirring to decompose excess LiAlH _4. Stir for 2 hours. Next, after suction filtration using a glass filter (G3), the solid matter on the filter was thoroughly washed with THF (120 mL), and the filtrate and the washing solution were combined and concentrated under reduced pressure. Water was completely removed from the obtained oily substance to obtain an oily product (N, N′-diethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidine). The yield was 12.1 g (93% yield).

Next, N, N, N ′, N′-tetraethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium diiodide was synthesized.
12.1 g (49 mmol) of the dipyrrolidine compound synthesized above was dissolved in 90 mL of ethanol (EtOH), and 17 ml (212 mmol) of ethyl iodide (EtI) was added dropwise with stirring, followed by stirring under reflux for 157 hours. After allowing to cool, 100 ml of acetone was added, and this was suction filtered through a glass filter (G3) to obtain a crystalline product. The crystalline product was washed by heating with acetone (80 ml × 2), allowed to cool, then washed successively with acetone (50 ml) and benzene (40 ml) and dried in vacuo. The yield of the product (N, N, N ', N'-tetraethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium diiodide) is 19.4 g (71% yield) Met.
The analytical value of the product is shown below.
¹ H NMR (400 MHz, D ₂ O) δ: 1.25 (12H, t, J = 7.2Hz, -CH ₃ ), 2.82 (8H, s, CH-C H ₂ -N ⁺ ), 2.89 (2H, s , -CH = CH-), 3.28 (8H, q, J = 7.5Hz, CH ₃ -C H ₂ -N ⁺ ), 3.78 (4H, d, CH-C H -CH ₂ ), 6.42 (2H, t , J = 3.8 Hz, -C H -CH =)
¹³ C NMR (100 MHz, D ₂ O) δ: 8.14, 8.99, 33.71, 40.59, 53.32, 56.24, 65.05, 134.75

Next, N, N, N ′, N′-tetraethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium dihydroxide was synthesized.
In an Erlenmeyer flask, N, N, N ′, N′-tetraethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium diiodide obtained in Production Example 1 (8.83 g, 15.8 mmol) was dissolved in distilled water (100 ml). To this, an ion exchange resin (Mitsubishi Chemical, DIAION, SA10A, OH form) (45 g) and distilled water (100 ml) were added and gently stirred at room temperature for 48 hours. This was filtered, concentrated under reduced pressure to 16.5 g, diluted to 28.7 g with distilled water, and N, N, N ′, N′-tetraethylbicyclo [2.2.2] oct-7-ene-2 3,5,6-dipyrrolidinium dihydroxide was obtained. As a result of titration with 0.05 M HCl, the concentration (as R ²⁺ ) was 0.516 mmol / g, and the exchange rate was 93.6%.
¹ H NMR (400 MHz, D ₂ O) δ: 1.21 (12H, t, J = 7.3Hz, -CH ₃ ), 2.77 (8H, s, CH-C H ₂ -N ⁺ ), 2.84 (2H, s , -CH = CH-), 3.24 (8H, q, J = 7.5Hz, CH ₃ -C H ₂ -N ⁺ ), 3.73 (4H, d, CH-C H -CH ₂ ), 6.37 (2H, t , J = 3.8 Hz, -C H -CH =)
¹³ C NMR (100 MHz, D ₂ O) δ: 7.93, 8.81, 33.62, 40.54, 53.17, 56.16, 64.95, 134.61

Example 1
In a 90 ml fluororesin (PFA) container, add 3.00 g of colloidal silica (DuPont, LUDOX (registered trademark) HS-40, SiO ₂ : 40 wt%), add 8.20 g of ultrapure water (milliQ) and stir for 10 minutes. did. Next, 0.156 g of aluminum hydroxide (Al (OH) ₃ , Pfaltz & Bauer) was dissolved and stirred for 10 minutes. After that, 1.23 g of potassium hydroxide (8 mol L-1 KOH solution: 6.097 mmol g-1, Wako) was added and stirred for 30 minutes, and the template synthesized in Production Example 1 N, N, N ′, N ′ -Tetraethylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium diiodide was added and stirred for 4 hours. Transfer the prepared gel to a 23 ml fluororesin container and use an autoclave (external dimensions 10 cm x 5 cmφ, internal dimensions 3.8 cm x 2.8 cmφ, internal volume 23 ml) at 160 ° C for 16 days (384 hours), rotation conditions Synthesis was performed at (20 rpm). The apparatus used for the synthesis is shown in FIG. The distance from the rotation axis center to the autoclave center is 8.4 cm.
After the synthesis, the autoclave was taken out and allowed to cool, followed by centrifugation (4000 rpm, 60 minutes × 5 times) using distilled water until the liquid became neutral. Thereafter, it was dried overnight in a 100 ° C. oven to obtain a white powder (as-synthesized).
Thereafter, firing was performed at 650 ° C. for 10 hours in an air atmosphere.
The obtained crystal was mordenite having an MOR structure (three letter code by IZA-SC) as shown in FIG. 2 in the X-ray diffraction pattern.
The obtained crystal was a microcrystal having a uniform shape having a length in the c-axis direction of about 100 nm and an aspect ratio of about 1.0, as shown in the scanning electron micrograph of FIG. .

Example 2
In this example, the product was observed by rotating the autoclave under the same conditions as in Example 1 and changing the rotation speed of the autoclave.
The heating temperature and time were fixed at 160 ° C. and 7 days (168 hours), respectively, and the rotation speed of the autoclave was changed to 0 (standing), 20, 40, 60, and 80 rpm. As a result, the product was amorphous at 0 rpm (stationary) and 80 rpm, and MOR (mordenite) at 20, 40 and 60 rpm. Mordenite was not synthesized outside the range of 20 to 60 rpm.
The X-ray diffraction pattern of the obtained product is shown in FIG. B (rotational speed 20 rpm), C (rotational speed 40 rpm) and D (rotational speed 60 rpm) showed X-ray diffraction patterns characteristic of the MOR structure (mordenite), but A (rotational speed 0 rpm, There are no peaks in the X-ray diffraction patterns of (stationary) and E (rotation speed of 80 rpm), indicating that crystals were not obtained (that is, amorphous was obtained).

The reason why mordenite was synthesized only in the range of the rotational speed of 20 to 60 rpm when the apparatus of FIG. 1 was used in this way is considered as follows.
The center (center of gravity) of the autoclave makes a uniform circular motion with a period of 1 / (rotational speed). The autoclave changes its direction as A to D by the rotational movement around the rotation axis. When the orientation of the autoclave changes in this way, the viscosity of the gel in the autoclave is high, so the gel moves in the opposite direction to gravity in the changed autoclave, and the entire gel is stirred (ie, the crystallization process). The reactants will fluidize.) However, if the rotational speed is too high, the movement of the gel cannot follow the rotational movement, and the entire gel is not stirred (that is, the reactant does not fluidize during the crystallization process). The effect of such agitation is a function of the rotation speed or the rotation period and can be defined by these. That is, the reactant can be flowed during crystallization by rotating the autoclave at a specific rotation speed and rotation cycle.

Example 3
In this example, a cumene cracking reaction was performed using the microcrystalline mordenite obtained in Example 1 (the following formula).
1 μL of substrate cumene (manufactured by TCI) was added to the reaction solution in pulses, and the benzene yield was measured for each pulse. The catalyst was used at 10 mg and 25 mg, and the reaction was carried out at 250 ° C. For the analysis of the product, a gas chromatograph apparatus (GC-8A manufactured by Shimadzu Corporation) equipped with a thermal conductivity detector (TCD) was used.
For comparison, a commercially available mordenite (catalyst society reference catalyst JRC-Z-HM20, length L 120-240 nm in the major axis (c-axis) direction, aspect ratio (L / D) 2.0-2.5) is used. The reaction was conducted in the same manner.
The conversion rate of cumene is shown in FIG. The microcrystalline mordenite of the present invention was found to have a smaller particle size, higher catalytic activity, and longer life compared to commercially available mordenite (JRC-Z-HM20).

Comparative Example 1
Crystallization was performed in the same manner as in Example 1 except that hydrothermal synthesis was performed under static conditions (0 rpm) using the same raw materials as in Example 1. The obtained X-ray diffraction pattern is shown in FIG. Mordenite with MOR structure was obtained under rotating conditions, while MCM-68 with MSE structure (three letter code by IZA-SC) was obtained under stationary conditions. Although amorphous was obtained under the stationary conditions of Example 2 (0 rpm, 168 hours), MCM-68 can be obtained by further increasing the synthesis time (384 hours).

Claims (3)

(1) Silica source, (2) N, N, N ′, N′-tetraalkylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium (provided that the alkyl group is The number of carbon atoms is 4 or less, and may be the same or different.) (3) Alkali metal hydroxide or alkaline earth metal hydroxide, and (4) a mixture of water, a comprises heating in flowing the mixture in an autoclave synthesized remained (as-synthesized) mordenite process, the mordenite composition formula _{R n Al n Si 48-n} O ₉₆ (wherein n represents 4 to 5 and R represents N, N, N ′, N′-tetraalkylbicyclo [2.2.2] oct-7-ene-2,3: 5,6-dipyrrolidinium. (However, the alkyl group has 4 or less carbon atoms and is the same. And may be different.) Represented by representative.) And synthesized remained (the as-Synthesized) preparation of mordenite having an X-ray diffraction pattern including the following values.
2θ (unit: degree) = 6.60 ± 0.10, 8.76 ± 0.10, 9.84 ± 0.05, 13.64 ± 0.05, 15.40 ± 0.10, 19.76 ± 0.10, 22.40 ± 0.10, 23.32 ± 0.10, 25.84 ± 0.10, 26.40 ± 0.10, 27.84 ± 0.10, 31.08 ± 0 .10, 35.84 ± 0.10 A method of producing mordenite comprising calcining as-synthesized mordenite obtained in claim 1, wherein the mordenite has the composition formula H _n Al _n Si _48-n O ₉₆ (wherein n represents 4 to 5), and a process for producing mordenite having an X-ray diffraction pattern including the following values.
2θ (unit: degree) = 6.60 ± 0.10, 8.86 ± 0.10, 9.88 ± 0.05, 13.56 ± 0.05, 15.40 ± 0.10, 19.76 ± 0.10, 22.36 ± 0.10, 23.32 ± 0.10, 25.80 ± 0.10, 26.40 ± 0.10, 27.84 ± 0.10, 31.08 ± 0 .10, 35.84 ± 0.10 The process according to claim 1 or 2, wherein flowing the mixture in the autoclave is rotating the autoclave at 20 to 60 rpm.