JP2534871B2 - Method for synthesizing zeolite ZSM-5 - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for synthesizing zeolite ZSM-5 useful as a catalyst and the like in the field of petrochemistry.

(Prior Art) As a method for synthesizing zeolite ZSM-5, a method using various nitrogen-containing organic compounds as templates has been proposed. For example, a method using various quaternary ammonium salts [Zeolite Molecular Sieves, 304-312; DWBrec
H., Wiley Inter Science (1974)], a method using amides (USP 4,472,366) and the like. The present applicant has also previously proposed a method using a lower alkylurea as a method for producing ZSM-5 at low cost and with high purity (Japanese Patent Laid-Open No. 36017/1987).

On the other hand, in recent years, some methods for synthesizing ZSM-5-like zeolite without using organic substances have been proposed (Japanese Patent Publication No. 56-49851).
No. 56-37215, Japanese Patent Publication No. 61-59246).

(Problems to be Solved by the Invention) In the method using various nitrogen-containing organic compounds, a large amount of organic compounds are usually used, and thus a large amount of organic substances are contained in the produced ZSM-5. Since these organic substances cannot be removed by a commonly used ion exchange method, it is usually necessary to remove them by air calcination at a high temperature of 500 ° C. or higher before ion exchange. However, such high temperature calcination has a problem that dealumination from the zeolite lattice occurs, resulting in deterioration of catalyst performance. On the other hand, instead of high-temperature calcination, a method has been proposed in which an organic substance is oxidized and removed from a zeolite containing a certain organic substance in a liquid phase using an oxidizing agent such as permanganate or hydrogen peroxide (JP 57-135718). However, even in this method, it is difficult to completely remove the nitrogen-containing organic compound, so that there is a problem in that the catalytic performance is deteriorated.

Further, when the amount of these organic compounds used is reduced, there is a problem that zeolite ZSM-5 is not produced or a large amount of by-products are produced, and it is not possible to obtain a catalyst having a satisfactory activity. I couldn't do it.

On the other hand, the synthetic method without using an organic substance has an advantage that an oxidation removal step is not essentially required, but this system has a problem that mordenite is very easily produced as a by-product, and ZS produced in the early stage
There is a problem that M-5 changes rapidly to mordenite and α-quartz sequentially.

(Means for Solving Problems) The inventors of the present invention have conducted diligent studies to solve the above problems, and as a result, in a system using a lower alkylurea as a template, the raw material has a limited composition. Range and pH
According to the above, it was found that the amount of lower alkyl urea used can be made extremely small, and ZSM-5 with high purity and stability can be obtained, and the present invention has been completed.

That is, according to the present invention, when an aqueous mixture containing a silica source, an alumina source and an alkali metal source is heated and crystallized in the presence of a lower alkylurea to synthesize zeolite ZSM-5, the pH of the aqueous mixture is 10 to 10. It also provides a method for synthesizing zeolite ZSM-5, which is characterized in that the composition is 12 and the composition thereof is in the following range.

SiO ₂ / Al ₂ O ₃ = 20 to 40 H ₂ O / SiO ₂ = 7 to 100 M ₂ O / SiO ₂ = 0.1 to 1.0 A / SiO ₂ = 0.00025 to 0.005 (where M is an alkali metal and A is lower) Alkylurea is expressed, and gram mols of oxides other than A are converted, and A is expressed in gram mol.) According to the method of the present invention, ZSM-5 having high crystallinity can be increased by using an extremely small amount of lower alkylurea. It can be obtained in purity. This is advantageous in terms of simplification of wastewater treatment and economic efficiency. Further, the advantage of the present invention is that
Even if a small amount of lower alkyl urea is used, the produced ZSM-5 still contains nitrogen-containing organic compounds.
Surprisingly, most of the nitrogen-containing organic compounds contained in this product can be removed from the zeolite by an ion exchange operation. This means that the usual firing at high temperature or the oxidation removal step using an oxidizing agent in the liquid phase is not necessary, which is not only advantageous in terms of process simplification and economy, It is also extremely advantageous in that the deterioration of the catalyst performance in the removal step is eliminated. It is not clear why the organic matter can be removed only by such an ion exchange operation, but it is considered that this is due to the combination of the lower alkyl urea template and the use of an extremely small amount thereof.

On the other hand, the present invention has another feature. that is,
Despite the very low amount of lower alkyl urea,
This is because the phase of ZSM-5 produced is extremely stable and the sequential conversion to mordenite or α-quartz is extremely slow as compared with the system using no organic matter. This means that high-purity ZSM-5 can be easily obtained as a result, which is very advantageous for industrial implementation.

As the silica source used in the present invention, sodium silicate, water glass, silica sol, silica gel, silicic acid anhydride and the like which are usually used for zeolite synthesis can be used, but water glass is preferable.

As the alumina source used in the present invention, aluminum sulfate, aluminum sulfate, sodium aluminate, aluminum hydroxide, alumina and the like which are usually used for zeolite synthesis are used.

As the alkali metal source used in the present invention, sulfates, nitrates, halides, hydroxides, aluminates and the like of alkali metals usually used in zeolite synthesis can be used, but hydroxides are preferred. Among the alkali metals, sodium is preferable.

The lower alkyl urea in the present invention has the general formula In expressed, to 1 of R _1, R _2, R ₃ 2 is an alkyl group having 3 or less carbon atoms, a compound remainder consisting of hydrogen atoms. Preferred lower alkyl urea is methyl urea,
1,3-dimethylurea, 1,1-dimethylurea, ethylurea,
1,1-diethylurea, 1,3-diethylurea, n-propylurea, i-propylurea, 1-methyl-1-ethylurea, 1-methyl-3-ethylurea and the like can be mentioned. Most preferred is dimethylurea.

The composition of the silica source, the alumina source, the alkali metal source, and the lower alkyl urea source in the aqueous mixture in the present invention is in the following range.

SiO ₂ / Al ₂ O ₃ = 20 to 40 H ₂ O / SiO ₂ = 7 to 100 M ₂ O / SiO ₂ = 0.1 to 1.0 A / SiO ₂ = 0.00025 to 0.005 (where M is an alkali metal and A is lower) Alkylurea, except for A, converted to gram moles of oxides, A is expressed in gram moles.) When the SiO ₂ / Al ₂ O ₃ molar ratio is less than 20, there are many mordenite by-products, and more than 40. Then, the by-product of α-quartz increases.

If the H ₂ O / SiO ₂ molar ratio is less than 7, the viscosity of the aqueous mixture will be too high and the composition of the raw gel will be non-uniform, and if it exceeds 100, the reaction rate will decrease. Productivity is low.

When the M ₂ O / SiO ₂ molar ratio is less than 0.1, it is difficult to obtain crystals, and when it exceeds 1.0, α-quartz becomes a by-product.

When the A / SiO ₂ molar ratio is less than 0.00025, Z is generated.
The change of SM-5 to mordenite is fast, and as a result, there are many by-products of mordenite, and when it exceeds 0.005, the nitrogen-containing organic compound contained in the produced ZSM-5 cannot be removed only by ion exchange.

The pH of the aqueous mixture in the present invention needs to be adjusted to 10-12. When the pH is lower than 10, it is difficult to obtain crystals, and when the pH is higher than 12, the mordenite by-product is increased. The preferred pH is 10.4-11.5. The pH adjustment of this aqueous mixture is adjusted by the amount of acid and alkali. Examples of the acid used in that case include inorganic acids such as sulfuric acid, hydrochloric acid and nitric acid, with sulfuric acid being preferred.

Seed crystals or seed slurry can be made to coexist in the aqueous mixture in the present invention, if necessary. When these substances coexist, there are advantages that the synthesis time is shortened and fine particle crystals are obtained.
On the contrary, it is disadvantageous to obtain a large crystal. When a seed crystal or seed slurry is used, the composition of the aqueous mixture refers to the composition including these.

The synthesis temperature in the present invention is 90 to 250 ° C, preferably 100 to 200 ° C, more preferably 130 to 190 ° C. The pressure may be any pressure as long as the reactant remains in the liquid phase, but it is preferably carried out under the self-generated pressure of steam. The synthesis time is not particularly limited because it depends on the temperature, but it is usually in the range of 5 to 100 hours.

In the present invention, it is preferable to carry out the synthesis under stirring.

The zeolite ZSM-5 synthesized in the present invention is ion-exchanged with a proton or various metal cations by a known method, if necessary, to give various cation-type ZSM-5.
Can be In particular, when it is used as a solid acid, it is preferably ion-exchanged with an inorganic acid such as nitric acid, sulfuric acid or hydrochloric acid to form the H type.

The zeolite ZSM-5 synthesized by the present invention can be used as a catalyst in various reactions. For example, hydration reaction of olefin or cycloolefin, synthesis of hydrocarbon from methanol, synthesis of aromatic from paraffin or olefin, and the like can be mentioned.

(Effects of the Invention) According to the method of the present invention, zeolite ZSM-5 can be synthesized with extremely high selectivity, and even when it is used as a catalyst, direct ion exchange can be performed without going through an oxidation removal step of organic substances. Therefore, a highly active catalyst can be obtained. These things
It is very advantageous for industrial implementation.

EXAMPLES Next, the present invention will be described with reference to examples. However, the present invention is not limited to these examples.

Example 1 Water glass (SiO ₂ 25.2% by weight, Al ₂ O ₃ 0.065% by weight, Na
₂ O 7.35 wt%, H ₂ O 67.5 wt%) (The same water glass is used in the following examples and comparative examples) 129 g, NaOH 0.64 g and H ₂
The solution was added _{O133g, Al 2 (SO 4)} 3 · 16H 2 O 9.7g and 1,3
A solution of 0.1 g of dimethylurea in 230 g of H ₂ O was added with stirring, and 139.4 g of 4.6 wt% sulfuric acid was added to obtain a homogeneous gel. The composition of this gel is the following values,
The pH was 10.6.

SiO ₂ / Al ₂ O ₃ = 35 H ₂ O / SiO ₂ = 52 Na ₂ O / SiO ₂ = 0.29 1,3-Dimethylurea / SiO ₂ = 0.0029 This raw material gel was placed in an autoclave of 1 at 185 ° C. and 6
Crystallized with stirring for 0 hours. The X-ray diffraction pattern after the obtained crystals were washed excessively and dried at 120 ° C. for 4 hours is shown in FIG. From FIG. 1, this product is ZSM-5.
Therefore, it was found that mordenite and α-quartz were scarcely contained. In addition, SiO ₂ / Al ₂ obtained by fluorescent X-ray analysis
The O ₃ ratio was 28, and the size of the crystal measured by a scanning electron microscope was a plate crystal having a thickness of about 1 micron and a width of about 3 micron. The amounts of carbon and nitrogen in the product obtained by elemental analysis were 0.10% by weight of carbon and 0.15% by weight of nitrogen.

This ZSM-5 was subjected to ion exchange in 1N HNO ₃ for 4 hours at room temperature, then washed, washed and dried at 120 ° C. for 4 hours to obtain H-ZSM-5.
I got Regarding the amounts of carbon and nitrogen determined by the elemental analysis of H-ZSM-5, carbon was not detected and nitrogen was 0.02% by weight. From this, it can be seen that most of the nitrogen-containing organic compounds were removed from the zeolite by ion exchange. Furthermore, the acidity of this H-ZSM-T was measured by the liquid phase ion exchange-alkali titration method (Fifth International Conference).
on Zeolites, 1980, P335), the acidity was 1.03 mmol / g, which was very close to the theoretical acid amount of 1.10 mmol / g calculated from the SiO ₂ / Al ₂ O ₃ ratio. .

Comparative Example 1 A homogeneous gel was obtained by using the raw materials having the same composition as in Example 1 except that 1.0 g of 1,3-dimethylurea was used. The composition of this gel had the following values and pH was 10.8.

SiO ₂ / Al ₂ O ₃ = 35 H ₂ O / SiO ₂ = 52 Na ₂ O / SiO ₂ = 0.29 1,3-Dimethylurea / SiO ₂ = 0.029 This gel was placed in an autoclave of 1 and heated to 185 ° C.
It was crystallized for 60 hours.

X-ray diffraction analysis after the obtained crystals were washed, washed and dried at 120 ° C. for 4 hours revealed that the product was ZSM-5 and contained almost no mordenite or α-quartz. In addition, the SiO ₂ / Al ₂ O ₃ ratio determined by fluorescent X-ray analysis is 28.
The size of the crystal obtained by measurement with a scanning electron microscope was a plate crystal having a thickness of about 1 micron and a width of about 3 micron. The amounts of carbon and nitrogen in the product obtained by elemental analysis were 0.5% by weight of carbon and 0.8% by weight of nitrogen.

HZ obtained by subjecting this ZSM-5 to ion exchange in 1N HNO ₃ for 4 hours at room temperature, then rinsing, washing and drying at 120 ° C. for 4 hours
The amount of carbon and nitrogen determined by elemental analysis of SM-5
It was 0.2% by weight and nitrogen was 0.3% by weight. The acidity determined by measuring the acidity was 0.80 mmol / g.

From the above results, it can be seen that the nitrogen-containing organic compound contained in the product cannot be completely removed only by ion exchange in the system in which a large amount of the nitrogen-containing organic compound is used.

Example 2 To a solution prepared by adding 0.8 g of NaOH and 133 g of H ₂ O to 100 g of water glass, 9.7 g of Al ₂ (SO ₄ ) ₃ · 16H ₂ O and 0.0 of 1,3-dimethylurea were added.
A solution prepared by dissolving 5 g in 230 g of water was added with stirring, and 140 g of 4.6% by weight sulfuric acid was further added to obtain a homogeneous gel. The composition of this gel had the following values and the pH was 11.0.

SiO ₂ / Al ₂ O ₃ = 26.2 H ₂ O / SiO ₂ = 74 Na ₂ O / SiO ₂ = 0.31 1,3-dimethylurea / SiO ₂ = 0.00135 This gel was placed in an autoclave at 1 and at 190 ° C.
While stirring with, extract the slurry over time,
After washing and drying at 120 ° C., the change in crystal phase was followed by X-ray diffraction analysis. The results are shown in FIG.

As is clear from Fig. 2, in this system, the generated ZSM
-5 phase is extremely stable and very pure ZSM-
It turns out that 5 is obtained.

Comparative Example 2 Example 2 except that 1,3-dimethylurea was not used.
A homogeneous gel was obtained with the same composition as. The pH of this gel was 10.8. Charge this gel in 1 autoclave,
The change over time was followed under the same conditions as in Example 2. FIG. 3 shows the results.

As is clear from FIG. 3, in the system using no organic substance, the phase change of the produced ZSM-5 into mordenite and α-quartz suddenly occurs, which makes it difficult to obtain high-purity ZSM-5.

Example 3 (1) Seed slurry synthesis A solution of 8.06 kg of water glass and 0.04 kg of NaOH and 3.2 kg of H ₂ O was added to 0.606 kg of Al ₂ (SO ₄ ) ₃ · 16H ₂ O and 9.4 of 1,3-dimethylurea. A solution of g in H ₂ O 14.4 kg was added with stirring, and 4.6 wt% sulfuric acid 10.6 kg was added to obtain a homogeneous gel. Charge this gel in 50 autoclave, 250 rpm
The synthesis reaction was carried out at 200 ° C. for 3 hours under the stirring conditions of.

120 ℃ after washing a part of the obtained slurry
X-ray diffraction analysis was performed after drying for 4 hours. As a result, the product was ZSM-5 having a crystallinity of 20%.

(2) Synthetic water glass 5.65 kg of NaOH 0.028 kg and H ₂ O 2.21 kg was added to a solution in a 50 autoclave, which was sealed and stirred with a slurry pump using a seed slurry 10.5 synthesized in (1). Add kg. In addition, pump Al ₂ (SO ₄ ) ₃
A solution of 0.424 kg of 16H ₂ O and 10 g of 1,3-dimethylurea in 10.08 kg of H ₂ O was added, and finally, 6.12 kg of 4.6% by weight sulfuric acid was added. The composition of this raw material slurry is the following value, pH
Was 11.1.

SiO ₂ / Al ₂ O ₃ = 36.5 H ₂ O / SiO ₂ = 55 Na ₂ O / SiO ₂ = 0.21 1,3-Dimethylurea / SiO ₂ = 0.0035 This raw material slurry is stirred at 150 ° C. for 30 hours at 260 rpm. Crystallized below.

The cake obtained after being filtered and washed with a centrifugal separator was put into 1N nitric acid to make a 10 wt% slurry, and ion exchange was carried out for 4 hours. The ion-exchanged slurry was again passed through a centrifugal separator, washed, and then dried at 120 ° C. for 12 hours.

The X-ray diffraction pattern of the thus obtained crystal is shown in FIG.
From FIG. 4, it was found that the product was ZSM-5 and contained almost no mordenite. Further, the SiO ₂ / Al ₂ O ₃ ratio determined by fluorescent X-ray analysis was 29, and the amount of carbon and nitrogen in the product determined by elemental analysis was such that no carbon was detected and nitrogen was 0.03% by weight. And very few.

Furthermore, the liquid-phase ion exchange - I connexion determined acidity alkaline titration method is 1.01 mmol / g, shows a very close to the theoretical acid content 1.08 mmol / g calculated from SiO ₂ / Al ₂ O ₃ ratio It was

Also, the size of the crystal measured by the scanning electron microscope is
The rod-shaped crystals were thin rods of about 0.1 × 0.1 × 0.7 micron, and the rod-shaped crystals were aggregates of fine crystals of 0.1 micron or less.

Comparative Example 3 A homogeneous gel was obtained by using the raw materials having the same composition as in Example 3 except that the amount of sulfuric acid was changed to adjust the pH to 9.5 and 12.3. This raw material was crystallized under the same conditions as in Example 1.

The obtained product was filtered, washed, dried at 120 ° C. for 4 hours, and then subjected to X-ray diffraction analysis.

As a result, the pH 9.5 system did not crystallize at all. In addition, in the system of pH 12.3, mordenite is 60% and the rest is
ZSM-5 was 20% and α-quartz was 20%.

Example 4 0.028 kg of NaOH and 2.21 kg of H ₂ O were added to 5.65 kg of water glass,
With stirring, 10.5 kg of the seed slurry obtained in Example 3 was added. Furthermore, a solution of 0.6 kg of Al ₂ (SO ₄ ) ₃ / 16H ₂ O and 15 g of 1,3-diethylurea in 10 kg of H ₂ O was added, followed by 2.9
6.0 kg of weight% sulfuric acid was added to obtain a homogeneous gel. The composition of this gel had the following values and the pH was 10.6.

SiO ₂ / Al ₂ O ₃ = 28.2 H ₂ O / SiO = 53 NaO / SiO ₂ = 0.24 1,3-diethylurea / SiO ₂ = 0.004 This gel was placed in an autoclave at 50 ° C.
Crystallization was performed for 0 hours under stirring conditions of 120 rpm.

The product obtained was filtered, washed, and dried at 120 ° C. for 4 hours, and then X-ray diffraction analysis revealed that the product was ZSM-5 and substantially free of mordenite.

This ZSM-5 was ion-exchanged in 1N HNO ₃ for 4 hours at room temperature, then filtered, washed, and dried for 4 hours at 120 ° C. The amount of carbon and nitrogen determined by elemental analysis was 0.01% by weight of carbon. ,
Nitrogen was 0.05% by weight.

Example 5 Using H-ZSM-5 obtained in Example 1, a hydration reaction of cyclohexene was carried out under the following conditions.

Charged capacity Cyclohexene 26 cc H ₂ O 174 cc Catalyst amount 40 g Reaction temperature 120 ° C. Pressure Self-generated pressure Stirring speed 800 rpm Equipment Glass autoclave Concentration of cyclohexanol in the oil phase 10 minutes after the start of reaction was 9% by weight.

Example 6 Using H-ZSM-5 obtained in Example 3, Example 5
Hydration reaction of cyclohexene was carried out under the same conditions as above.

10 minutes after the start of the reaction, the concentration of cyclohexanol in the oil phase was 12.3% by weight.

Comparative Example 4 Using H-ZSM-5 obtained in Comparative Example 1, a hydration reaction of cyclohexene was performed under the same conditions as in Example 5.

The concentration of cyclohexanol in the oil phase 10 minutes after the start of the reaction was 6.9% by weight.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction pattern of the composition obtained in Example 1, 2
FIG. 3 is a graph showing the results of investigating changes in the crystal phase by X-ray diffraction analysis in Examples, and FIG. 3 is a graph showing the results of investigating changes in the crystal phase by X-ray diffraction analysis in Comparative Example 2. FIG. 4 is an X-ray diffraction pattern of the product obtained in Example 3.

Claims (2)

(57) [Claims] 1. When synthesizing zeolite ZSM-5 by heat crystallization of an aqueous mixture containing a silica source, an alumina source and an alkali metal source in the presence of a lower alkylurea, the pH of the aqueous mixture is 10 to 12. And a composition thereof is within the following range: A method for synthesizing zeolite ZSM-5. SiO ₂ / Al ₂ O ₃ = 20 to 40 H ₂ O / SiO ₂ = 7 to 100 M ₂ O / SiO ₂ = 0.1 to 1.0 A / SiO ₂ = 0.00025 to 0.005 (where M is an alkali metal and A is lower) Alkylurea is represented, and gram moles of oxides other than A are converted, and A is represented by gram moles.) 2. A lower alkyl urea is methyl urea, 1,3-dimethyl urea, 1,1-dimethyl urea, ethyl urea, 1,1-diethyl urea, 1,3-diethyl urea, n-propyl urea,
The method according to claim 1, which is i-propylurea, 1-methylethylurea, or 1-methyl-3-ethylurea.