JPH0159965B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides oxygen-containing organosilicon, aluminum,
A titanium or zirconium compound is mixed in a solution containing a polar compound with polydentate or bridging coordination ability to form a homogeneous solution, and then through a gelation process in which the entire sol is gelled from a homogeneous sol by hydrolysis. After drying the gel at low temperature, a heat treatment step is performed to scatter the polar compounds remaining in the gel, thereby changing the polydentate or crosslinking coordination ability of the polar compound and its structure to the target silicon, A method for producing homogeneous amorphous silicon, aluminum, titanium, or zirconium oxide, which is used for homogeneous amorphization, pore design, or surface design of aluminum, titanium, or zirconium oxide. It is related to. Amorphous silicon, aluminum, titanium, or zirconium oxides have many uses, such as catalysts, adsorbents, sensors, optical semiconductors, and magnetic materials, and there are correspondingly various synthesis methods. Other than this, the synthesis methods can be summarized into the following two methods. In other words, there are two methods: precipitating metal oxides or metal hydroxides by adding acid or alkali to an aqueous solution of inorganic metal salts, and dissolving metal alkoxides in ethanol, propanol, etc. and adding water to the solution. This method involves hydrolysis to obtain metal oxides or metal hydroxides. Although the former method is simple, it has the disadvantage that it is difficult to eliminate impurities contained in the raw materials, and salts used to generate precipitation are easily incorporated as impurities. In the latter method, the metal alkoxide can be easily purified by distillation or sublimation, so it is relatively easy to eliminate impurities, but it is not easy to make it porous or control the expansion of the surface area. When silicon, aluminum, titanium, or zirconium oxides are used as catalysts, adsorbents, or sensors, the surface area and pores of the oxides are always important issues. Methods for controlling the surface area and pore structure include adding polyethylene glycol, polyvinyl alcohol, polyacrylamide, or cellulose ether to the gel immediately after hydrolysis or drying, washing the gel with monohydric alcohol, acid treatment, etc. There are methods such as water treatment and firing treatment, each of which has its own advantages. However, these methods are limited to special materials such as alumina, and it is difficult to control over a wide range using only individual methods. may change. Other controlled porosity methods include methods for producing porous glass. With this method, the pore diameter can be changed from tens of angstroms to several thousand angstroms by heat treatment and acid treatment.
The scope of application is extremely narrow, as it is limited to the production of composite metal oxides. The present inventors kept the above points in mind and conducted various studies to produce homogeneous and amorphous silica, alumina, titania, or zirconia with controlled surface area and pores, and as a result, the present invention was achieved. It has been reached. The present invention provides a method for treating one or more oxygen-containing organosilicon, aluminum, titanium, or zirconium compounds at a temperature of 10°C to 100°C.
One of the polar compounds with polydentate or bridging coordination ability
A homogeneous solution is obtained by mixing a species or two or more species in a solution, followed by a gelation process in which the entire sol is transformed from a homogeneous sol into a gel by hydrolysis, and the gel remains in the gel after drying at low temperature. Uniform amorphization of silicon, aluminum, titanium, or zirconium oxides for the purpose of polydentate or crosslinking coordination ability and structure of polar compounds by applying a heat treatment step to scatter polar compounds;
Homogeneous amorphous silica, alumina, which is characterized by its use in pore design or surface area design.
The present invention provides a method for producing titania or zirconia. That is, since the first step in preparing homogeneous silica, alumina, titania, or zirconia is to create a homogeneous solution, oxygenated organosilicon, aluminum, titanium, or zirconium compounds and polydentate or cross-linked It is important to keep in mind that the polar compound having potential becomes a homogeneous solution without forming a precipitate. For this purpose, oxygenated organosilicon, aluminum, titanium,
Alternatively, the combination of a zirconium compound and a polar compound having polydentate or crosslinking coordination ability, and the mixing temperature are often important issues. For example, oxygen-containing organometallic compounds such as aluminum, titanium, and zirconium, especially alkoxides, produce precipitates that are insoluble in ethylene glycol and propanediol. It is necessary to select alcohols and oxygen-containing compounds with a high degree of branching (dihydric alcohols, keto alcohols, oxycarboxylic acids). On the other hand, oxygen-containing organometallic compounds of silicon, especially these alkoxides, do not have this problem, and almost all dihydric alcohols, amino alcohols, keto alcohols, ketocarboxylic acids, oxycarboxylic acids, dicarboxylic acids, etc. can be used. can. If the mixing temperature is too high, an abnormal reaction may occur between the polar compound used and the oxygen-containing organosilicon, aluminum, titanium, or zirconium compound, resulting in the formation of an insoluble precipitate, so it is necessary to avoid excessive heating. Temperature: 10℃~100℃, preferably 20℃~80℃
℃ is good. In addition, when the mixing temperature is high, hydroxyl groups are easily etherified and carboxyl groups are easily esterified, and in this case, the multidentate and crosslinking coordination abilities of polar compounds are significantly reduced. is preferably 20°C to 80°C. Next, the amount of polar compounds to be used is an important issue in order to compensate for the decrease in polar compounds due to unavoidable etherification and esterification, and to ensure smooth solization and gelation. The amount of polar compounds with polydentate or cross-linking coordination ability is important for the pore and surface design of the final metal oxide, but if it is too small, gelation will not proceed smoothly and problems may occur during hydrolysis. It often causes precipitation and takes a long time. If the amount used is too large, the gel will not be uniformly gelled, and the gel will float in the solution, and also in this case, gelation will take a long time. Therefore, the amount of the compound with polydentate or cross-linking coordination ability should be determined from oxygen-containing organic silicon, aluminum, titanium,
Alternatively, the molar ratio is preferably from 0.01 to 15, particularly preferably from 0.1 to 5, relative to the amount of the zirconium compound used. The amount of water used is also important for gelation; if the amount is too small, gelation will take several days or more, and if it is too large, uniform gelation will be difficult. For example, if an oxide precipitate is formed without gelation, the absolute amount of polydentate or crosslinking polar compounds in the metal oxide will decrease, and eventually porosity and surface area expansion will proceed smoothly. do not have. Therefore, the amount of water used during hydrolysis is in a molar ratio of 0.5 to 20 with respect to the oxygen-containing organosilicon, aluminum, titanium, or zirconium compound;
1 to 10 are particularly suitable. The oxygen-containing organosilicon, aluminum, titanium, or zirconium compounds used in the present invention are sometimes difficult to hydrolyze depending on the metal species and ligands. In such a case, if a hydrolysis accelerator such as an acid or an alkali is used, hydrolysis can proceed quickly and gelation can be smoothly performed.
As the hydrolysis accelerator, any ordinary inorganic acid, organic acid, inorganic alkali, or organic alkali can be used as long as it is soluble, but if you do not want the hydrolysis accelerator to remain in the final metal oxide, ,
Hydrolysis accelerators include organic acids (carboxylic acids, ketocarboxylic acids, oxycarboxylic acids, etc.) or organic alkalis (amines, amino alcohols, etc.) such as formic acid, cilic acid, tartaric acid, malonic acid, succinic acid, ethanolamine, propanolamine, etc. It is better to use By the methods and operations described above, a homogeneous gel can generally be smoothly produced within several hours. Next, the jelly-like or agar-like gel is ground to an appropriate size and dried at a temperature of 80°C to 110°C under reduced pressure for several hours to 30 hours. The amorphous metal oxide is completed by performing heat treatment after drying and scattering the remaining polydentate or polar compounds with cross-linking coordination ability. The temperature and atmosphere may be set in the range of 200 to 700°C depending on the intended use of the oxide. In this case, all usual heat treatment methods can be employed, and it is also possible to combine several heat treatment methods. For example, heat treatment can be performed only in a hydrogen atmosphere, or in oxygen or air. Furthermore, after heat treatment in oxygen, air, or inert gas, it is also possible to further heat treat in a hydrogen stream. The silicon, aluminum, titanium, or zirconium oxides produced by the methods described above are confirmed to be amorphous and homogeneous by powder X-ray diffraction and electron microscopy, and
Surface area measurement by BET method and methylpentane and n
- Surface area and pore distribution were determined by measuring pores using a pulse adsorption method using adsorption of hexane, etc., and it was confirmed that surface area and pores were controlled by the manufacturing method. That is,
For silica, the surface area depends on the polar compound used.
The pore size is 150 to 1000 m ² /g, the pore diameter is distributed below 50 Å, and the pore volume is 0.01 to 0.4 cm ³ /g. Also,
For alumina, the surface area varies from 50 to 850 m ² /g, depending on the polar compound used, and for titania, it varies from 0.4 to 60 m 2 /g.
In the case of m ² /g zirconia, control was possible between 0.4 and 15 m ² /g. Such control of surface area and pores, particularly over a wide range of silica and alumina, is extremely difficult with conventional manufacturing methods, and has been made possible by the present invention. The amorphous silicon, aluminum, titanium, or zirconium oxides obtained in this way are highly homogeneous and can be used as adsorbents, sensors, optical semiconductors, etc.
It can be fully used as a catalyst, and in particular, it can be effectively used as a catalyst for oxidation, isomerization, cracking, hydration, hydrogenation, etc. Next, the present invention will be explained in more detail with reference to Examples. Example 1 Put 4 g of methanol containing 10% hydrogen chloride in a 200 ml beaker, add 50 g of ethylene glycol and 63.3 g of tetraethoxylan, and add 65
Stir at ℃ for 3 hours. Next, 11.5 g of water was added and stirred for another hour at the same temperature, and then 12 g of water was added again and stirred at the same temperature to obtain a gel in which the entire solution solidified into agar-like form. After the gel was left at the same temperature for 1 hour, it was further left at 25°C overnight. Next, crush the gel to an appropriate size, place it in a 200 ml eggplant-shaped flask, and dry it in a rotary evaporator at 100°C under reduced pressure for 24 hours. Yield: 25.6g (approximately 1.4 times the calculated value of _SiO2 ). The dried gel was pulverized, spread in a quartz tube, and heat-treated at 400°C for 8 hours in a hydrogen stream. Silica was obtained in exactly the same manner using various diols instead of ethylene glycol.
Table 1 shows the physical property values. Example 2 Put 15 ml of tert-butanol in a 300 ml beaker, add 50 g of pinacol, and warm at 45°C to completely dissolve. Next, 9.3 g of aluminum sec-butoxide was added, and after warming at 65°C for 2 hours with stirring, tert containing 5.5 g of water was added.
- Add 100ml of butanol solution and add 2 more at the same temperature.
Warm while stirring for an hour. Furthermore, when 50 ml of tert-butanol containing 5.5 g of water is added and stirred at the same temperature, it solidifies into agar-like form. The subsequent operations are the same as in Example 1. In addition, similar operations were performed using various polar compounds instead of pinacol.
Various aluminas were obtained. Table 2 shows the physical property values. Example 3 Put 15 ml of ethanol in a 50 ml beaker, add 1 g of methanol containing 10% hydrogen chloride,
Furthermore, 17.4 g of titanium iso-propoxide was added and heated at 80°C for 20 minutes. Next, add 45 ml of ethanol containing 1.5 g of water and warm at the same temperature for 2 hours, then add 20 ml of ethanol containing 1.5 g of water again.
ml and while stirring at the same temperature, it gels into a jelly. The subsequent operations were carried out in the same manner as in Example 1, except that the heat treatment temperature was 300°C. Surface area 50.2m ² /g. Example 4 Put 15 ml of ethanol in a 300 ml beaker, add 50.1 g of pinacol, and dissolve by heating at 45° C. for 30 minutes. To this solution, 50.7 g of zirconium n-propoxide and 2 g of methanol containing 10% hydrogen chloride were added, and the mixture was heated at 65° C. for 3 hours with stirring. Next, 60 ml of an ethanol solution containing 5.5 g of water is added, and while stirring at the same temperature, it becomes a gel. The subsequent operations were the same as in Example 1 except that the heat treatment was performed at 350°C. Surface area 13m ² /
g.

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Claims (1)

[Claims] 1. Oxygen-containing organosilicon, aluminum, titanium, or zirconium compounds are mixed with one or more polar compounds having polydentate or crosslinking coordination ability at a temperature of 10°C to 100°C. A homogeneous solution is obtained by mixing the sol in a solution containing the sol, followed by a gelation process in which the entire sol is gelled from a homogeneous sol by hydrolysis, and after drying the gel at a low temperature, the polar compounds remaining in the gel are dispersed. By applying a heat treatment process, the polydentate or cross-linking coordination ability of a polar compound and its structure are utilized for homogeneous amorphization, pore design, or surface design of the target inorganic oxide. A method for producing homogeneous porous silica, alumina, titania, and zirconia. 2 Oxygen-containing organosilicon, aluminum, titanium,
and the zirconium compound is one or a mixture of two or more of alkoxides, ketoalcohol compounds, diketone compounds, ketocarboxylic acid compounds, oxycarboxylic acid compounds, and carboxylic acid compounds. 3. A patent claim in which the polar compound having polydentate or crosslinking coordination ability is one or a mixture of two or more of dihydric alcohols, amino alcohols, keto alcohols, diketones, ketocarboxylic acids, oxycarboxylic acids, and dicarboxylic acids. Method of scope 1. 4. The method according to claim 3, wherein the dihydric alcohol is one or a mixture of two or more diols having 14 or less carbon atoms. 5 The mixing ratio of a polydentate or polar compound having crosslinking coordination ability and an oxygen-containing, organosilicon, aluminum, titanium, or zirconium compound is from 0.01 to 15 in terms of molar ratio (polar compound/organometallic compound).
The method according to claim 1. 6. The method according to claim 1, wherein the mixing ratio is from 0.1 to 5 in molar ratio. 7 Mixing and hydrolysis temperature of raw material compounds is 20℃
80°C. 8. Claim 1, wherein the amount of water used during hydrolysis is 0.5 to 20 in molar ratio (water/oxygen-containing organometallic compound) to the oxygen-containing organosilicon, aluminum, titanium, or zirconium compound. Section method. 9. The method according to claim 1, wherein the molar ratio during the hydrolysis is from 1 to 10. 10. The method according to claim 1, wherein the heat treatment temperature is from 200°C to 700°C.