JP4113943B2 - Tubular structure made of amorphous aluminum silicate, method for producing the same, and adsorbent using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel amorphous aluminosilicate tubular body having excellent adsorption ability and a method for producing the same.
Furthermore, the present invention is superior in adsorption function, affinity with water or ion exchange capacity due to its high surface activity, and by utilizing the high specific surface area and pores and its form, it can reduce the storage of natural gas and the humidity of the living environment. The present invention relates to an adsorbent composed of amorphous tubular aluminum silicate applicable to autonomously controlled humidity control materials, harmful pollutant adsorbents, deodorizing materials, quick-drying desiccants, and the like, and a synthesis method thereof.
[0002]
[Prior art]
Tubular aluminum silicate is naturally produced as imogolite, but not only is the area of soil producing natural imogolite limited, but the production is extremely small. From such a background, a method for synthesizing a high-purity tubular aluminum silicate using a specific inorganic substance solution has been studied and has already been developed (JP 2001-64010 A, JP 2001-220129 A). Issue gazette).
[0003]
Although the above synthesis method has been established, in order to obtain a tubular aluminum silicate, it becomes an inhibiting factor for the tube elongation reaction from a solution prepared by mixing an inorganic silicon compound solution and an inorganic aluminum compound solution. After removing the coexisting ions, there is a problem that heat treatment at 100 ° C. for 2 days is required to grow the material form from the precursor into a tube shape. Furthermore, the obtained tubular aluminum silicate is not suitable as a material that requires a quick response to the adsorption / desorption reaction because it is not easy to move the adsorbed substance from the opening of the tube to the inside. It was.
[0004]
[Problems to be solved by the invention]
This invention is made | formed in view of the above-mentioned actual condition in a prior art. That is, an object of the present invention is to provide a tubular body made of an excellent amorphous aluminum silicate capable of rapidly adsorbing and desorbing various substances at low cost. Another object of the present invention is a tubular amorphous aluminosilicate having high surface activity and excellent adsorption capacity, affinity with water or ion exchange capacity, and having a high specific surface area and a large number of fine pores. To provide an adsorbent comprising:
[0005]
[Means for Solving the Problems]
As a result of further earnest research toward the development of a novel inorganic adsorbing material based on a new aluminum silicate having a good adsorbing ability, the present inventors have found that the basic properties of adsorbing substances are minimal. It is sufficient that the unit structure is a tubular body that is repeated at a certain cycle, and it is confirmed that the unit is hardly affected by the length of the tube. The inventors have found that a tubular body made of an acid salt can be obtained, and have completed the present invention.
[0006]
That is, the present invention is a tubular structure made of amorphous aluminum silicate having fine pores. The amorphous aluminum silicate has a pore having a diameter of 0.5 to 50 nm, preferably a pore having a diameter of 0.5 to 2.0 nm, and has no specific peak in X-ray diffraction. It shows an amorphous diffraction pattern.
[0007]
Also, manufacturing methods of the tubular structure consisting of an amorphous aluminum silicate having fine pores in the present invention, forming a precursor tubular aluminum silicate by mixing an inorganic silicon compound solution and an inorganic aluminum compound solution Then, by increasing the anion concentration of the precursor solution, the growth of the precursor in the subsequent heating process is suppressed.
[0009]
Furthermore, the adsorbent of the present invention is characterized by using a tubular structure made of amorphous aluminum silicate having fine pores. When this adsorbent is disposed in a high humidity room, water vapor in the room can be easily adsorbed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The tubular structure of the present invention is formed of amorphous aluminum silicate, and generally has an outer diameter of 2.2 to 2.8 nm, an inner diameter of 0.5 to 1.2 nm, and a length of 20 nm. It consists of the following tube-shaped hollow bodies, and the tube-shaped body has a lot of micropores with a nanometer (nm) diameter. The diameter of the micropore is 0.5 to 5.0 nm, preferably 0.5 to 2.0 nm.
This tubular structure is a porous body having a large amount of micropores through which water molecules and the like can enter and exit, has a high surface activity, and has a large surface area, so that it has a good adsorption capacity and desorption capacity. Because of its excellent affinity and ion exchange capacity, it can be used as a humidity control material that autonomously controls the humidity of the living environment, storage of natural gas, adsorbents of harmful pollutants, deodorizing materials, and quick-drying desiccants. Applicable.
[0011]
In the method for producing a tubular structure of the present invention, an inorganic silicon compound and an inorganic aluminum compound are used as raw materials. The reagent used as the silicon source may be a monosilicate compound, and specific examples thereof include sodium orthosilicate, sodium metasilicate, amorphous colloidal silicon dioxide (such as Aerosil) and the like. On the other hand, the aluminum source to be bonded to the silicate molecule may be an aluminum ion, and specifically includes aluminum compounds such as aluminum chloride and aluminum nitrate. These silicon sources and aluminum sources are not limited to the above compounds, and can be used in the same manner as long as they have the same effect.
[0012]
In the present invention, each of these raw materials is dissolved in an appropriate aqueous solution to prepare a solution having a predetermined concentration. Next, these solutions are mixed and reacted. At that time, even if they are mixed at an arbitrary ratio, there is no problem in the formation of the precursor, but preferably the silicon / aluminum ratio is 0.5 to 1.0. Mix to become. The concentrations of the silicon compound solution and the aluminum compound solution are the precursors produced by synthesis from any concentration, but suitable concentrations include 1 to 500 mmol / l silicon compound solution and 1 to 1000 mmol / l aluminum compound solution. It is preferable to mix.
After mixing a silicon compound solution with this aluminum compound solution, an alkaline solution is dropped, and the pH is adjusted from weakly acidic to near neutral to form a precursor.
[0013]
Examples of the alkaline solution used for the neutralization reaction in the precursor generation step include solutions of sodium hydroxide, potassium hydroxide, ammonia, and the like. Examples of the acidic solution in which the precursor is dispersed include hydrochloric acid, sulfuric acid, nitric acid, perchloric acid and the like. The amorphous tubular aluminum silicate is preferably synthesized in the range where the pH of the solution at the time of heating is about 3-6.
[0014]
Next, after removing the coexisting ions in the solution from the solution containing the precursor using an appropriate means such as centrifugation, filtration or membrane separation, the recovered precursor is dispersed in pure water or acidic aqueous solution. . Thereafter, the obtained precursor dispersion is aged by heating.
In the present invention, in order to suppress the growth due to elongation of the obtained aluminum silicate precursor, when the dispersion solution is heated and aged, 1) the ion concentration in the solution is set high, and 2) the heating time is set. 3) At least one means selected from shortening the heating temperature, that is, an operation of any one of these 1) to 3) or a combination of two or more thereof. Thereby, the tubular body of the target amorphous aluminum silicate can be obtained as solid content.
[0015]
In the present invention, when increasing the ion concentration in the solution before the heat aging process, it is particularly important to increase the anion concentration, and the anion concentration in the solution is 10 mmol / l or more. An anion concentration of 100 mmol / l is preferred. The material used to make the dispersion solution have a high ion concentration is not particularly limited, and specific examples include hydrochloric acid, sodium chloride, potassium chloride and the like.
[0016]
When adjusting the reaction conditions in the heating and aging process, when shortening the heating time, heating is performed for 48 hours or less, preferably 3 to 12 hours in a temperature range of 95 to 120 ° C. Moreover, when making heating temperature low, it heats for 1 hour or more in the temperature range of 40-60 degreeC, However, The heating for 5 days or more is preferable. These heating methods and heating conditions are not particularly limited, but specifically, it is preferable to heat using a mantle heater or an autoclave.
[0017]
The aluminum silicate tubular body obtained by the above method is a tubular hollow body made of an amorphous material and having a short length, a large specific surface area, and a large number of fine pores. Therefore, it can be used as an adsorbent for various substances, utilizing its excellent properties such as adsorptivity, collecting and storing substances, dehumidifying, drying moisture, removing harmful substances, storing flammable substances and It can be used for deodorization and the like, and particularly when placed in a high humidity room, it can be used as an adsorbent for easily adsorbing water vapor in the room.
[0018]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.
Example 1
125 ml of sodium orthosilicate aqueous solution diluted with pure water was adjusted so that the SiO ₂ concentration was 100 mmol / l. Separately from this, aluminum chloride was dissolved in pure water to prepare 125 ml of 150 mmol / l aqueous solution.
Next, the sodium orthosilicate aqueous solution was mixed with the aluminum chloride aqueous solution and stirred with a magnetic stirrer. The silicon / aluminum ratio at this time is 0.67. Furthermore, 22 ml of 1N sodium hydroxide aqueous solution was dropped into this mixed solution to adjust the pH to around 6.
The precursor was recovered from this solution by centrifugation, and the precursor was further washed by centrifugation three times with pure water, and then dispersed in 2 l of pure water.
6 ml of 5N hydrochloric acid was added to 2 l of this precursor suspension, and then heated at 100 ° C. for 2 days using a mantle heater. After heating, ammonia was added to the product to obtain a gel product, which was then recovered and dried in a dryer at 40 ° C. for about 2 days to obtain a tubular aluminum silicate.
[0019]
As shown in FIG. 1, the obtained aluminum silicate exhibited an X-ray diffraction pattern indicating that it was amorphous without specific peaks in powder X-ray diffraction. The pore distribution curve has a peak at a pore radius of about 0.6 nm as shown in FIG. 2, and this pore corresponds to a pore inside the tube. Further, as shown in FIG. 2, the water vapor adsorption isotherm adsorbed about 18% by weight of water vapor at 20% relative humidity and about 27% by weight at 96% relative humidity.
[0020]
【The invention's effect】
Since the tubular body made of the amorphous aluminum silicate of the present invention is made of a hollow inorganic substance having a length of about 20 nm having a large number of fine pores having a nanometer diameter, water molecules, low molecular weight inorganic substances and Since organic substances can be used as adsorbents that can quickly adsorb and desorb in large quantities, it can be used in a wide range of industrial fields as moisture adjustment such as humidity adjustment, removal of harmful substances, storage of adsorbed substances and desiccants Is. Further, according to the production method of the present invention, a tubular body made of amorphous aluminum silicate having the above-described excellent adsorption characteristics can be synthesized at a low cost.
Therefore, the present invention is a technology that can easily provide a high-performance porous material, and is extremely significant in contributing to the industrial world.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction pattern of a synthetic amorphous aluminum silicate obtained in an example of the present invention.
FIG. 2 is a pore diameter distribution curve of a synthetic amorphous aluminum silicate obtained in an example of the present invention.
FIG. 3 shows a water vapor adsorption isotherm using a synthetic amorphous aluminum silicate obtained in an example of the present invention.

Claims (6)

  A tubular structure made of amorphous aluminum silicate having fine pores.   The tubular structure according to claim 1, wherein the amorphous aluminum silicate has fine pores having a diameter of 0.5 to 50 nm and exhibits an amorphous diffraction pattern in X-ray diffraction.   The tubular structure according to claim 1 or 2, wherein the micropore has a diameter of 0.5 to 2.0 nm. After the inorganic silicon compound solution and the inorganic aluminum compound solution are mixed to form a tubular aluminum silicate precursor, the precursor solution is grown in the subsequent heating process by increasing the anion concentration of the precursor solution. A method for producing a tubular structure made of amorphous aluminum silicate having fine pores, wherein From the amorphous tubular aluminum silicate having micropores according to claim 4, wherein the inorganic silicon compound solution and the inorganic aluminum compound solution are mixed so that the molar ratio of silicon / aluminum is 0.5 to 1.0. A method for producing a tubular structure.   An adsorbent characterized by using a tubular structure made of amorphous aluminum silicate having fine pores.

Images