JPS6027646A - Manufacture of alumina formed body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for producing an alumina molded body.

Conventionally, heavy oils such as those left after distilling crude oil and tar sands oil are hydrotreated to make them lighter, but at the same time the sulfur compounds contained in the heavy oil are removed.

Efforts are being made to reduce nitrogen compounds, organometallic compounds, etc.

A catalyst is generally used in such hydrotreating.

Alumina carriers are well known as such carriers. Hydrogenation catalysts have been prepared by supporting active metals on alumina supports. As mentioned above, hydrotreating involves carrying out reactions such as hydrogenolysis, desulfurization, demetallization, denitrification, and deoxygenation in the presence of a catalyst, and the catalyst's activity, selectivity,
Lifespan and strength are the key factors. It is generally believed that the size and pore distribution of the pores of the catalyst play a major role in the characteristics of such catalysts.

Furthermore, the shape of the catalyst, whether it is spherical, pellet-like, or lattice-like, is also an important factor.

The field of application of tertiary alumina compacts is gas separation using ceramic membranes. Gas separation using a ceramic membrane uses an alumina membrane made by controlling the pore diameter and pore volume, and uses the difference in the mean free path of the mixed gas components of two or more mixed gases to separate each gas. It is called separation. In order to perform complete gas separation efficiently, it is necessary to take measures such as making the membrane tubular in shape.

From this viewpoint, various methods have been proposed for controlling the pore diameter and pore volume of an alumina carrier or a gas separation membrane. Typical methods include adding organic substances, alcohol treatment, and acid treatment. A conventional method for controlling the pore diameter and pore volume of an aluminum molded body will be explained below.

The alumina used for the catalyst carrier and gas separation membrane is mainly γ-alumina, which is one of intermediate aluminas. The manufacturing method is to neutralize or exchange decompose aluminum salts and aluminates, or to hydrolyze aluminum amalgams and aluminum alkoxides with water or steam to generate a total boehmite (AAOOH) sol, which is
It is fired at 00°C (generally 600°C).

The method of adding an organic substance to control the pore diameter and pore volume is a method of controlling by adding a water-soluble organic polymer f such as polyethylene glycol, polyvinyl alcohol, polyacrylamide, etc. The effect on pore distribution and pore volume when all of these are added differs depending on the type of additive. Furthermore, the effect differs depending on whether it is added immediately after the boehmite sol is produced or after it is dried. However, this method has the disadvantage that although it is effective for controlling the pore volume in %IIJ, it is not effective for controlling the pore size.

The alcohol treatment method is a method in which the boehmite sol immediately after generation is washed with various alcohols to control the pore diameter. In this case, ethyl alcohol, phlegm alcohol, and n-butyl alcohol are highly effective.3 However, when an alcohol with a larger molecular weight than hexyl alcohol is used, the effect is no longer observed. This method has a narrow controllable width for controlling the pore diameter, and it is not possible to create pores with a diameter of 150A or more.

The acid treatment method is a method in which acids are added to the generated boehmite sol, followed by dehydration, molding, drying, and firing to control the pore diameter. In this method, the pore distribution shifts towards smaller pores.

Conventionally, after drying the boehmite sol prepared as described above, a small amount of water is added or the water is gradually removed to make the sol a suitable viscosity for the molding equipment. Next, a molding device is used to mold the catalyst carrier into spheres, pellets, or lattice shapes, or into tubular shapes for gas separation membranes, and after drying and firing, the catalyst carrier or gas separation membrane is obtained. .

However, in this method, the boehmite sol exhibits peculiar behavior as a sol, which causes great difficulties at the time of molding, and it has been difficult to carry out the molding process constantly. In other words, when the amount of water is large relative to the boehmite sol, molding is easily performed. However, because it is soft, the shape of the molded items may be deformed, or the molded items may stick or stick to each other. On the other hand, when the amount of water is small, the mold becomes hard and the load on the molding machine increases. Furthermore, as heat is generated during molding, the water in the rubermite sol evaporates due to the heat, making it even harder, and eventually the load on the molding machine becomes so great that the molding machine has to stop.

When manufacturing using all boehmite sol, such as catalyst carrier or gas separation membrane, there were such major problems at the molding stage.

The present invention has been made in view of this point, and provides a method for producing an alumina molded body that can easily produce a catalyst carrier or a gas separation membrane having a predetermined performance.

That is, the present invention' is a method for producing an alumina molded body in which a boehmite sol and a fired boehmite sol are uniformly mixed, then molded, dried, and fired.

Here, pemai and tosil are, for example, aluminum salts,
It can be obtained by neutralizing or exchange decomposing an aluminate, or by hydrolyzing an aluminum amalgam or aluminum alkoxide with water or steam.

The present inventors have completed the present invention by paying attention to the following points. That is, normal catalyst carriers or gas separation membranes are fired at 500°C to 900°C (generally 600°C). At this temperature, the boehmite sol becomes γ-alumina, which is intermediate alumina. The r-alumina transferred from the boehmite sol functions as a catalyst carrier or a gas separation membrane. r-alumina does not exhibit stickiness even when beimito sol and diluted water are added.

In the present invention, boehmite sol and boehmite sol are preliminarily calcined at a temperature of 500 to 600° C. to form γ-alumina, and then finely ground γ-alumina is uniformly mixed. Next, this is formed into a spherical, pellet or lattice shape in the case of a catalyst carrier using a molding device. In the case of a gas separation membrane, it is formed into a tubular shape, then dried and fired. As a result, in the catalyst carrier or gas separation membrane obtained by the method of the present invention, the viscosity of the boehmite sol is not affected by the amount of water and is maintained in a state convenient for molding in a molding device, making molding very easy. Since it is easy to manufacture, manufacturing efficiency can be improved. Further, the catalyst carrier or gas separation membrane produced according to the present method has performance equivalent to that of a catalyst carrier or gas separation membrane obtained by molding only boehmite sol.

Examples of the present invention will be described below.

Aluminum isoproposite AlIC0CB H,)
200 parts by weight of No. 8 was dissolved in 1000 parts by weight of distilled water kept at 80° C. to perform hydrolysis. After that, this f:15
After hydrothermal treatment at 0°C for 12 hours, hydrochloric acid was added at a molar ratio of 0.05 to Ai and treated at 95°C for 24 hours.
Boehmite sol was obtained by time peptization.

Next, the boehmite sol was dried and then calcined at 500° C. for 2 hours to form γ-alumina, which was then finely pulverized to obtain γ-alumina powder. An attempt was made to manufacture the above-mentioned porous pipe for gas separation using a push-pull molding machine in which this alumina powder and the boehmite sol from which water had been removed were thoroughly mixed. In this case, the moisture content was easily controlled, and porous tubes of a predetermined shape could be manufactured at a rate of approximately 100%.

Next, the porous tube thus obtained was heated at a heating rate of 100° C./hour from room temperature to 600° C., maintained at 600° C. for 2 hours, and then left to cool to obtain a fired porous tube product.

The pore size distribution and pore volume of the fired porous tubes were measured using the mercury intrusion method.

Comparative Example 1 In order to compare with Example 1, a boehmite sol similar to that used in Example 1 was kept in a dry state at 110°C to remove moisture. Then extrusion molding it-
Using this method, an attempt was made to manufacture a porous tube for gas separation with a diameter of 4-1, a wall thickness of 10 mm, and a length of 30 mm. In this case, it was difficult to control the moisture content, and the rate at which porous tubes with a predetermined shape could be obtained was only 1/10.

Figure 1 shows the fine details of the porous tube fired product of Comparative Example 1 containing only boehmite sol and the porous tube fired product of Example 1 containing boehmite sol and γ-alumina powder at a mixing weight ratio of 50%. FIG. 3 is a diagram showing the relationship between pore radius and pore volume.

In FIG. 1, the horizontal axis shows the pore radius, and the vertical axis shows the pore volume.

Figure 1 shows data for a porous tube made of a single boehmite sol, and ■ shows data for a porous tube made of a mixture of boehmite sol and γ-alumina powder. Almost no difference was observed between the two in terms of pore size distribution and pore volume.

Next, a gas separation test was conducted on each of the porous tubes of Example 1 and Comparative Example 1, which were produced using the entire gas separation test apparatus. The gas composition on the inlet side is 50% hydrogen and 50% nitrogen, the inlet side pressure is 3 Ky/d%, the outlet side pressure is IK? kd
,! : Measured by

As a result of the test, the gas composition on the outlet side was 69% hydrogen for both.
It was found that a sample containing 31% nitrogen exhibited the same separation performance.

Example 2 Aluminum sulfate (Ai2 (SO4) s) 10
0 parts by weight were dissolved in 1000 parts by weight of distilled water, and IN sodium hydroxide was added to adjust the pH to 10. Boehmite sol kumquats were prepared, dried, and further calcined at 500° C. for 2 hours. Next, after mixing the fired product and boehmite sol at a solid weight ratio of 50:50, 1.
Extrusion granulation was carried out to 6Uφ, and after drying, it was calcined at 600° C. for 2 hours, and an alumina catalyst carrier was prepared as a prototype, and the pore size distribution and total pore volume were measured.

Comparative Example 2 The following comparative example was conducted for comparison with Example 2. That is, aluminum sulfate (A4 (SO41m) 100
Part by weight was dissolved in 1000 parts by weight of distilled water, and the pH was adjusted to pH by adding IN sodium hydroxide.

A boehmite sol was obtained by preparing the following.

Thereafter, extrusion granulation was performed to a size of 1.61L11φ, and after drying, it was calcined at 600° C. for 2 hours to prepare an alumina catalyst carrier, and the pore size distribution and pore volume were measured.

In this case, granulation was difficult.

The measurement results of the pore size distribution and pore volume of Example 2 and Comparative Example 2 are shown in FIG. In FIG. 2, the horizontal axis shows the pore radius, and the vertical axis shows the pore volume. In the figure, ■ is a granulated product of only the boehmite sol of Comparative Example 2, and IV is a granulated product of a mixture of the boehmite sol and the fired product of Example 2. No significant difference was observed in pore size distribution and pore volume between the two.

Example 3 Sodium aluminate (NaA10t) 1000 Ji
' was dissolved in 101% distilled water, and then all of the IN sulfuric acid was added to make the solution acidic with sulfuric acid to a pH of 4 to obtain a boehmite sol. Next, IN sodium hydroxide was added to adjust the pH to 9. This was autoclaved for 10 hours under saturated steam pressure at 180°C. Then, the boehmite sol was completely dried at 500°C.
After firing, the powder was pulverized and autoclaved. This boehmite sol was mixed at a solid weight ratio of 50=50, extruded into pellets of 1.2.0 IIJIφ, dried, and dried at 600°C.
An alumina carrier was obtained by firing for a period of time.

Granulation in this case was easy.

Comparative example 3 The following comparative example was conducted for comparison with Example 3.

Sodium aluminate (NaA70t) 10001!
k10! After dissolving in distilled water, IN sulfuric acid was added to make it acidic with sulfuric acid to a pH of 4 to obtain a boehmite sol.Next, IN sodium hydroxide was added to adjust the pH to 9. After autoclaving this for 10 hours under saturated steam pressure at 180°C, water molecules up to 25% were removed.2. O
The pellets were extruded into Mφ pellets and dried. Thereafter, it was fired at 600° C. for 2 hours to obtain an alumina carrier.

Extrusion granulation was difficult with this method.

The results of measuring the pore size distribution and pore volume of Example 3 and Comparative Example 3 are shown in FIG. In FIG. 3, the horizontal axis shows the pore radius, and the vertical axis shows the pore volume. Also, in the same figure, ■ is an alumina carrier made only from boehmite sol, and ■ is an alumina carrier made from boehmite sol and a fired product. The pore size distribution and pore volume of both cases were in good agreement, and there was no discernible difference due to the manufacturing method of the alumina carrier.

As explained above, according to the method for producing an alumina molded body according to the present invention, a catalyst carrier or a gas separation membrane having a predetermined performance can be easily obtained.

[Brief explanation of the drawing]

FIGS. 1 to 3 are characteristic diagrams showing the relationship between the pore volume and the pore radius of the alumina porous tube and the alumina carrier. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A method for producing an alumina molded body, which comprises uniformly mixing boehmite sol and a fired boehmite sol, followed by shaping, drying, and firing.