JPS58161916A - Manufacture of mordenite having high content of silica - Google Patents

Abstract

PURPOSE:To manufacture mordenite with high silica content for enabling a selective hydrocarbon converting reaction and having a specified content or strength distribution of a solid acid by hydrothermally treating mordenite and by bringing it into contact with a strong acid. CONSTITUTION:Mordenite as a starting material is converted into a hydrogen exchanger or a precursor of a hydrogen exchanger by an exchange method using an acid soln. or an exchange method using an ammonium salt, and it is hydrothermally treated at >=600 deg.C in the presence of steam. AlOH<2+> separated from the skeleton structure of the mordenite by the hydrothermal treatment and present in cavities and metallic Al present at a relatively weak part of the skeleton structure are then treated with an acid such as >=4N hydrochloric acid or nitric acid. Thus, the ratio of silica/alumina in the mordenite is adjusted to 50-200, and mordenite with high silica content for enabling a selective hydrocarbon converting reaction and having a specified content or strength distribution of a solid acid is manufactured.

Description

[Detailed Description of the Invention] Technical Field This invention relates to a method for increasing the silica/alumina molar ratio of a crystalline aluminone silicate zeolite having a mordenite crystal structure and controlling its solid acid number and solid acid strength distribution. More specifically, the present invention relates to a method for producing a high silica-containing mordenite having a specific amount of solid acid or solid acid strength distribution while increasing the silica/alumina molar ratio to 50 or more.

BACKGROUND ART Mordenite, a type of crystalline aluminosilicate, has a network structure centered on a three-dimensional skeleton in which tetrahedrons of 5104 and AlO2 are cross-linked by sharing oxygen atoms. The charge balance of the aluminum-containing tetrahedra is also balanced by the inclusion of cations, such as alkali metal cations or alkaline earth metal cations, in the crystal. In addition to natural products, mordenite 1 can be obtained chemically.When the alkali metal cation is sodium, it is generally represented by a unit cell shown in the following formula.

4Na20''4A403・40Si02'2JH20 Generally, in order to effectively use such mordenite as a catalyst for hydrocarbon conversion, most of the contained cations must be replaced with cations that exchange ions with catalytically active metal cations or hydrogen ions. It is necessary to develop the properties as a solid acid and increase the reaction activity through exchange treatment.

Since mordenite itself has a relatively high silica/alumina ratio from the beginning, conversion to hydrogen-type mordenite by this cation exchange operation can be performed by ordinary ammonium ion exchange with ammonium chloride and treatment with a relatively weak acid. can be achieved. Furthermore, when treated with a relatively strong acid, not only the cation exchange reaction but also the aluminum in the crystal lattice is removed, the silica/alumina ratio in mordenite is further increased, and when used as a catalyst, hydrogen cracking and thermal decomposition isomerization It is known that it exhibits high activity in hydrocarbon conversion reactions such as oxidation and disproportionation.

Conventional methods for increasing the silica/alumina ratio in mordenite include a method of producing aluminum-deficient mordenite with an extremely high silica/alumina ratio by treating it with mineral acids under relatively severe conditions of temperature and contact time (
(Japanese Patent Publication No. 46-14334), in order to enhance the extraction effect of aluminum with acid, hydrogen exchange type or its precursor is calcined and then aluminum is leached with acid.
Method for obtaining mordenite with lyca/alumina ratio
6-57166), a method of increasing the molar ratio of 7 Lika/alumina in crystalline aluminosilicate by carrying out an alternating multiple circulation operation of steam treatment and acid extraction (Japanese Patent Publication No. 57166),
15DOO Publication) is known.

However, although these operations can increase the silica/alumina ratio in mordenite, catalysts with controlled solid acid amount or solid acid strength distribution that are selectively active in reactions of various hydrocarbons cannot be obtained. It wasn't.

That is, when the conventional method is used to increase the silica/alumina ratio of mordenite, the amount of solid acid is either too large or too small, making it impossible to control the amount of solid acid.

Summary of the Invention The present inventors investigated a method for controlling solid acid 1 in crystalline aluminosilicate, and found that mordenite was heat-treated in the presence of water vapor by contacting hydrothermally treated gold with a strong acid. The present inventors have discovered a method for producing a high silica-containing mordenite having a specific solid acid amount or solid acid strength distribution that enables a silica/alumina ratio of 50 to 200 and a selective hydrocarbon conversion reaction. It is something.

That is, the present invention is prepared by converting mordenite into a hydrogen exchange type or a hydrogen exchange type precursor, treating it at a temperature of 600°C or higher in the presence of water vapor, and then bringing it into contact with an acid. This is a method for producing high-silica-containing mordenite.

Raw mordenite The raw mordenite used in the present invention may be either natural or synthetic. In addition, the mordenite is converted into a hydrogen ion type or hydrogen ion precursor before hydrothermal treatment, but the raw material mordenite may bind an alkali metal or alkaline earth metal cation, and the type of mordenite may be any metal cation. good.

Hydrogen exchange type or hydrogen exchange type precursor The hydrogen exchange type or hydrogen exchange type precursor can be prepared by an exchange method using the above raw material mordenite with an acid solution or an ammonium salt. Mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid are used. The concentration of this acid is preferably 0.5 normal or more. The hydrogen ion exchange reaction is usually preferably carried out at a temperature range from room temperature to 100°C, and heating is desirable because the conversion reaction is accelerated. Furthermore, the conversion reaction can be promoted by replacing the solution with fresh solution during the reaction.

Hydrothermal treatment The hydrothermal treatment in the present invention is a heat treatment in the presence of steam, and by appropriately selecting the steam partial pressure and treatment temperature, the mordenite with a high silica/alumina ratio produced by acid extraction can be heated. The amount of solid acid can be controlled.

The water vapor during hydrothermal treatment is the gas used for the treatment, preferably the water vapor partial pressure in the air is 1% to 100%, especially 5% to 40%.
%, and the treatment temperature is preferably 600°C to 1000°C, particularly 650°C to 750°C. If the treatment is carried out at a temperature below this range or in the absence of water vapor, solid rancidity cannot be controlled, and only mordenite with large solid rancidity is obtained, which cannot be used as a catalyst for selective hydrocarbon conversion reactions.

The hydrothermal treatment can be carried out for 1 to 10 hours, preferably 2 to 5 hours, to fully demonstrate its effects.

In this way, the control of the amount of solid acid in the present invention is closely related to the water vapor partial pressure, treatment temperature, and treatment time in the hydrothermal reaction, and the desired specific amount and strength of solid acid can be achieved by combining these. A high silica content mordenite with a distribution can be obtained. In this case, the higher the water vapor partial pressure and the higher the treatment temperature, the smaller the solid sour.

Generally, water vapor-containing gases are obtained by bubbling Papler air immersed in a bath maintained at a constant temperature. When using equipment such as natural gas or liquefied petroleum gas reactors, the necessary water vapor partial pressure can be obtained by adjusting the excess air.

Acid Extraction Treatment Hydrothermal treatment removes the AtOH''+ existing in the cavity from the mordenite skeleton structure and aluminum metal located in a relatively weak skeleton structure is eluted and removed by the acid treatment of the present invention.

The acids used in this treatment are hydrochloric acid and nitric acid.

Inorganic acids such as sulfuric acid and phosphoric acid, and organic acids such as acetic acid, acetic chloride, acetic trichloride, citric acid, tartaric acid, and oxalic acid can be used. Among these, inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid are preferably used. Furthermore, when using these acids for extraction treatment, it is preferable to use those with a concentration of 1N or higher, preferably 6N or higher.

The acid extraction treatment is preferably carried out at a temperature ranging from room temperature to 100°C. By acid extraction of mordenite obtained by hydrothermal treatment under the above conditions, silica/
Mordenite with an alumina ratio of 50 to 200 is obtained.

Furthermore, this acid extraction treated mordenite is 400 l, -t
The mordenite, which is in an unstable crystalline state, is stabilized by performing the hydrothermal treatment at relatively milder conditions than the hydrothermal treatment conditions, preferably at 50° C. to 600° C.

According to the present invention, it is possible to obtain a mordenite having a high degree of crystallinity and having a silica/alumina ratio of 50 to 200, preferably 70 to 180, by controlling the amount of solid acid.

Solid Acid Amount and Solid Acid Strength Distribution The solid acid content and solid acid strength of the highly silica-containing mordenite obtained by the present invention are measured by a temperature programmed desorption method. That is, the amount of adsorption is determined by adsorbing a basic substance onto a solid or a point, then increasing the temperature and quantifying the basic substance that is desorbed. The adsorption amount of this basic substance is directly related to the amount of solid acid, and the temperature at which the basic substance is desorbed is directly related to the strength of the solid acid, so it is possible to know the relative amount of solid acid and solid acid strength distribution. be able to.

The basic substances used in this temperature programmed desorption method include ammonia, pyridine, n-butylamine, etc. Among them, the amount of pyridine desorbed can be easily quantified using a hydrogen ion detection method. This is preferable because it adsorbs to Bronsted acid, which is an acid site, as a pyridinium ion, and to a Lewis acid site, as a coordinate bond pyridine, so that the amount of acid can be analyzed relatively accurately.

When the treatment method according to the present invention is used, a highly silica-containing mordenite with a pyridine adsorption amount of 0.04 mmol to a35 mmol per 1f of mordenite is obtained.

In hydrothermal treatment, if the steam partial pressure is increased and the treatment temperature is increased, the amount of solid acid will be less, but if the steam partial pressure is lowered and the treatment temperature is lowered, the amount of solid acid will be increased.

As described in the effect of the invention, among the high silica-containing mordenite whose solid oxygen is controlled by the present invention, those having an acid film with an adsorption amount of biridin of less than 5 mmol of mordenite fff1pα do not have any special acid activity. As mordenite,
It can be used for adsorption and fractionation treatment of various hydrocarbons.

Furthermore, by supporting metals with special reaction activity on mordenite, which has a low acidity, it has no effect on compounds that polymerize at high acidity, and can selectively perform certain reactions such as oxidative hydrogenation. It can be used to catalyze reactions that occur within the mordenite lattice and yield only specific isomers.

Moreover, those having an acid amount of 105 to 1.25 mmol can selectively react only a specific reaction of hydrocarbons or a specific compound in a hydrocarbon mixture. For example, when separating n-olefins and isoolefins, which have very similar boiling points, it is possible to selectively activate the tertiary carbon of the olefins to form carbonium ions and dimerize and remove only the isoolefins.

Further, those having an acid amount of α25 mmol or more are useful as catalysts for hydrocarbon conversion such as thermal cracking and hydrogen cracking.

Next, the present invention will be specifically explained using examples.

However, the present technology is not limited to the examples.

Example 1 100 f of commercially available highly crystalline sodium mordenite (manufactured by Two-Tone, trade name: Zeolon 90ONa, composition shown in Table 1) was mixed with 1N hydrochloric acid 500.
The sample was immersed in the liquid and stirred at 80° C. for 1 hour. After finishing, remove the acid solution by decanting method and add 50% fresh 1N hydrochloric acid.
0- was poured into the solution, and the mixture was stirred at 80° C. for 1 hour. After removing the hydrochloric acid solution, the sample was washed with warm water until no chlorine ions were detected. Next, hot air drying was performed at 110° C. to obtain a hydrogen ion exchange type precursor of mordenite (the composition is shown in Table 1).

The obtained hydrogen ion exchange type precursor was heated gradually from room temperature under 30% water vapor partial pressure and subjected to hydrothermal treatment at 650°C for 4 hours.

After cooling, reflux treatment was performed at 90° C. for 6 hours using 12N hydrochloric acid 500° C. to extract aluminum. After removing the hydrochloric acid solution, the sample was washed with warm water until no chlorine ions were detected, and then dried with hot air at 110°C. After air drying, it was fired at 650° C. for 3 hours using a Matsufuru furnace to obtain highly silica-containing mordenite. The obtained mordenite had the composition shown in Table 1.

Next, the starting material sodium type mordenite, the hydrogen ion exchange type precursor obtained as described above was calcined in a Matsufuru furnace at 600°C for 3 hours, and the solid acid l was obtained by pyridine adsorption on the hydrogen type mordenite and highly silica-containing type mordenite. and solid acid strength distribution were measured by the following method.

Each of the above three types of mordenite is pulverized into 30 to 100 meshes, calcined at 500°C for 1 hour to remove adsorbed moisture, etc., and 0.075 f is precisely weighed and charged into a reactor. On the other hand, a bubbler containing pyridine was immersed in a water bath maintained at a constant temperature of 15.5°C, and pyridine was adsorbed with nitrogen. Next, the temperature of the reactor was gradually raised to 300° C. under nitrogen flow, and the temperature was maintained at 300° C. until the physically adsorbed pyridine was desorbed. After confirming that pyridine desorption was no longer observed by gas chromatography, the reactor was heated from 300 to 950 °C at a rate of 10 °C/min, and the desorbed pyridine was detected by gas chromatography. I decided. The amount of pyridine desorbed is proportional to the amount of solid acid in mordenite, and the desorption temperature is correlated to the strength of the solid acid. The results are shown in Table 1.

As is clear from Table 1, the amount of solid acid in the sodium-type mordenite used as the starting material is smaller than that in the high-silica-containing mordenite obtained by the present invention, and on the contrary, it is larger in the hydrogen-exchanged type mordenite. It can be seen that the solid acid amount and solid acid strength of mordenite are controlled. Furthermore, the results of X-ray powder diffraction analysis of the high-silica-containing type mordenite confirmed that it was a crystalline mordenite that was almost the same as the crystallinity of the IJ type mordenite used as the starting material. Furthermore, it is known that the interplanar spacing changes due to the removal of aluminum, and in the case of this example, for example, 2θ=30.
It was confirmed that the peak at 9° was shifted to 31.6° due to dealumination.

Comparative Example 1 Using the same sodium type mordenite as in Example 1 as a starting material, a hydrogen ion exchange type precursor was prepared in the same manner. After air drying, it was fired at 650° C. for 4 hours while gradually increasing the temperature in the absence of water vapor using a Matsufuru furnace. Thereafter, dealumination treatment with hydrochloric acid and calcination were performed in the same manner as in Example-1.

The composition of this mordenite and the results of pyridine adsorption 1 measured in the same manner as in Example 1 are shown in Table 1.

Examples 2 to 3 Hydrogen ion exchange precursors were prepared using the same starting materials and the same method as in Example 1. After air-drying, the precursor was filled into a tubular flow-type atmosphere firing furnace, and the temperature was raised to 120℃, and the steam partial pressure was 6.
At 5% and 100%, gradually increase the temperature to 650℃~700℃
Hydrothermal treatment was performed at ℃ for 3 hours. Thereafter, dealumination treatment with hydrochloric acid and calcination were performed in the same manner as in Example-1. Table 1 shows the composition of this mordenite and the adsorption amount of pyridine.

Examples 4 to 5 Mordenite was prepared using the same starting materials as in Example-1 and using the same method as in Example-1 except that nitric acid or sulfuric acid was used in place of hydrochloric acid.The acid concentration was also ion-exchanged. 1N was used, and in the case of aluminum extraction treatment, 12N was used. Table 2 shows the chemical analysis values and measurement results of pyridine adsorption amount.

Table 2 Example 6 67f of aluminum sulfate and 11g of concentrated sulfuric acid in 1500f of pure water
9.7f, dissolve sodium chloride 1402, add water glass (No. 3) 190f to it, and add 2.5 to Neo・A/aos・23S1・99min 0
An aqueous reaction mixture was obtained having a composition consisting of: After this mixture was aged at room temperature for about 1 hour, it was put into an autoclave, the temperature was rapidly raised, and the temperature was maintained at 180° C. for 20 hours. The obtained solid product was cooled to room temperature, filtered, thoroughly washed with water, and then dried at 110°C. Part of the product in the air7
The drained water calcined at 00°C was adsorbed at room temperature and chemically analyzed to obtain synthetic mordenite with the following composition.

800℃ ignition loss 10.0% by weight Sing
79. I IfAj203
5.96 ttNa20"
5.51 To ttSl/To AA (molar ratio)
It was confirmed by X-ray powder diffraction analysis that a part of the 22.61 product had a mordenite crystal structure based on its interplanar spacing.

The obtained synthetic mordenite) 100F was treated in exactly the same manner as in Example 1 to obtain a high-silica-containing mordenite. The composition and adsorption amount of pyridine were as follows.

800℃ scorching heat reduction 3.2 weight%5i
02 95.1 5kLx03
1.22 11Na pick-up
α11〃5IO2/A14o
! (molar ratio) 133 hyinodine 1 supported ii (m
mol)/f-87+ite)''-ゝTotal pyridi 2nd place
Q, 108aoo-soo℃ desorption amount 0.020500-600℃ desorption amount
0.033 Examples 7 to 8 A hydrogen ion exchange type precursor was prepared using the same starting material 100f as in Example-1 and using the same method.

After air drying, the obtained precursor was divided into equal parts, and one part was subjected to hydrothermal treatment at 700°C for 3 hours in the presence of 5% water vapor and the other part 20% water vapor. After cooling, each was diluted with 12N hydrochloric acid.
The aluminum was extracted by reflux treatment at 90° C. for an hour. Thereafter, each was thoroughly washed with 2,500 ml of hot water to remove chlorine ions. “After air drying, it was calcined for 3 hours at 700°C in a Ma-Sofle furnace to obtain a high-silica-containing mordenite.Table 6 shows the analytical values and the amount of pyridine adsorbed.

Table 5 Agent: 1) Akira Agent Ryo Hagi Hara -

Claims (1)

[Claims] A method for producing high-silica-containing mordenite, which comprises converting mordenite into a hydrogen exchange type or a hydrogen exchange type precursor, treating it at a temperature of 600° C. or higher in the presence of water vapor, and then contacting it with an acid.