JPH10158033A - Porous crystalized glass having cuti2(po4)3 crystal as skeleton and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous crystallized gals having a large specific surface area without increasing a pseudo-specific surface area by a physical pulverizing method, by melting a source material containing copper oxide, titanium oxide and phosphoric acid, cooling at specified temp. and forming crystal nuclei of CuTi2 (PO4 )3 and Cu3 (PO4 )2 . SOLUTION: A source material containing 21.8 to 29.3wt.% copper oxide, 5.9 to 10.0wt.% titanium oxide, and 64.8 to 67.3wt.% phosphoric acid is fused and rapidly cooled at >=800 deg.C/sec cooling rate to crystallize. The obtd. glass is kept at 450 to 500 deg.C for >=10 hours to form crystal nuclei of CuTi2 (PO4 )3 and Cu3 (PO4 )2 , and heat treated to grow the two kinds of crystal nuclei. Then Cu3 (PO4 )2 is completely eluted and removed by using >=0.1 N acid such as hydrochloric acid and sulfuric acid at room temp. to obtain a porous crystallized glass having >=10m<2> /g specific surface area and CuTi2 (PO4 )3 crystal as a skeleton.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to CuTi ₂ (PO ₄ )
_{The present} invention relates to a method for producing a porous crystallized glass having a _three- crystal structure. More specifically, CuT, which is expected to have antibacterial properties and catalytic action
The present invention relates to a production method capable of efficiently and inexpensively producing a porous crystallized glass using i ₂ (PO ₄ ) ₃ crystal as a skeleton.

[0002]

2. Description of the Related Art Porous materials are widely used, such as catalyst carriers, various filters, gas sensors, and packing materials for chromatography. The features required for each of these applications are different. For example, when used as a high-temperature gas filter, it is necessary to select a material that does not react with the passing gas and have a structure with a small pore diameter and a small pressure loss that can reliably catch a substance to be collected. Therefore, the material composition and the manufacturing method of the porous material differ depending on the application. For example, CuTi ₂ (PO ₄ ) ₃ containing Cu (I) can be considered as a crystal expected to have a catalytic action for the decomposition of nitrogen oxides. When used as a catalyst, a very important point is how efficiently the substance to be treated can contact the catalyst at the same time as the material itself has a catalytic action. Therefore, various methods for increasing the specific surface area of the catalyst itself have been studied. However, it is possible to produce a material having a CuTi ₂ (PO ₄ ) ₃ crystal structure by a powder sintering method, but its specific surface area is almost equal to 0 m ² / g. This is because the composition ratio of copper oxide, titanium oxide, and phosphoric acid as raw materials for obtaining a CuTi ₂ (PO ₄ ) ₃ crystal structure. When a CuTi ₂ (PO ₄ ) ₃ crystal whose specific surface area obtained by the powder sintering method is almost 0 m ² / g is used, a method of pulverizing the material is used in order to increase the specific surface area in a pseudo manner. . However, there is no other method than the physical pulverization of the material other than physical pulverization, and furthermore, there is a limit in the physical refinement, and it is difficult to improve the specific surface area to a desired level. When the finely divided powder is used as a porous material, it is used by filling it in a container such as a column.However, the finer the particles of the powder to be filled, the higher the filling rate in the container and the pressure loss. There is a problem that it becomes large. As a countermeasure,
Various methods for producing porous crystalline materials have been attempted.
For example, in the powder sintering method, there is a method in which a low melting point raw material other than the target composition raw material is compounded at the time of compounding the raw material, and the low melting point raw material is eluted during sintering to form voids. However, in this case, there are problems that continuous pores cannot be obtained due to poor dispersibility of the low-melting-point raw material component, and deformation during firing or fusion to a furnace material occurs due to a large amount of a flux component. Further, as another method, a production method has been developed in which a glassy matrix component is removed after firing to form voids while leaving only a crystalline skeleton component, that is, a phase separation phenomenon of glass. This is because Na ₂ O—O—B ₂ O ₃ —S
After phase separation by glass treatment of an iO ₂ (SiO ₂ : 70 wt%), a component soluble in acid (Na ₂ O—B)
₂ O ₃ ) is eluted to form a porous silica glass body, but requires a high temperature treatment, resulting in a high treatment cost.
Since the material component is limited to silica-based glass, there is a problem that other crystals, that is, a material made of CuTi ₂ (PO ₄ ) ₃ cannot be formed.

[0003]

SUMMARY OF THE INVENTION The present invention relates to CuTi
_An object of the present invention is to efficiently and inexpensively produce a porous, high specific surface area crystallized glass having a ₂ (PO ₄ ) ₃ crystal structure and having no need to increase a pseudo specific surface area by physical grinding. .

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a porous material having an inexpensive and highly efficient CuTi ₂ (PO ₄ ) ₃ crystal structure can be obtained by utilizing the phase separation phenomenon of glass. It has discovered a method for producing a crystallized glass. That is, two types of glasses containing the desired composition are obtained by spinodal decomposition. Neither of the two separated phases has a specific shape, and the glass has a structure in which the two phases are entangled, resulting in high efficiency. The raw materials used are copper oxide, titanium oxide, and phosphoric acid. Copper oxide 21.8
-29.3wt%, titanium oxide 5.9-10.9wt
%, Phosphoric acid 64.8-67.3 wt%. If each raw material is not in the mixing ratio, C
Two components of uTi ₂ (PO ₄ ) ₃ and Cu ₃ (PO ₄ ) ₂ are not generated. In order to rapidly cool and vitrify the molten material, the temperature decreasing rate is 800 ° C./sec or more, preferably 1000 ° C./s.
ec or more. If the temperature is lower than 800 ° C./sec, crystallization occurs and glass cannot be obtained. CuTi ₂ (PO ₄ )
_{Both 3} and Cu ₃ (PO ₄ ) ₂ do not vitrify by themselves, but a system using them as pseudo-two components has a significantly lower liquidus temperature and can be obtained as a stable glass. The resulting glass has a porosity of 0% and is not porous. Next, in order to generate crystal nuclei of CuTi ₂ (PO ₄ ) ₃ and Cu ₃ (PO ₄ ) _2, 1
Hold for at least 0 hours. When the temperature is lower than 450 ° C., no crystal nucleus is generated, and when the temperature is higher than 500 ° C., the growth of the generated nucleus is more rate-determining than the generation of the nucleus. The desired specific surface area is not obtained. If the holding time is less than 10 hours, a sufficient amount of nucleation cannot be obtained. Further, it is necessary to grow the generated nuclei. If the crystal growth is not sufficiently performed, an extremely large amount of amorphous (glass) portion remains, and a good skeleton cannot be obtained. By these heat treatments, CuTi ₂ (P
A crystallized product (crystallized glass) comprising two types of crystal phases of O ₄ ) ₃ and Cu ₃ (PO ₄ ) ₂ is obtained. By pickling the obtained crystallized product with an acid such as hydrochloric acid or sulfuric acid of 0.1 N or more, only the desired CuTi ₂ (PO ₄ ) ₃ crystal is obtained. That is, CuTi ₂ (PO ₄₎ never soluble in ₃ hydrochloric acid or acids such as sulfuric acid, is because Cu ₃ (PO _{4) 2} dissolves, the location after the melted of Cu ₃ (PO _{4) 2} It becomes a void and becomes a porous body. Acid concentration of 0.
If it is less than 1N, the elution efficiency will be significantly reduced. Preferably, 1N or more acid is used. The specific surface area of the porous body needs to be 10 m ² / g or more, and if it is less than 10 m ² / g, no surface activity can be obtained.

Next, an embodiment will be described in detail. (Example) A raw material according to the present invention, which was mixed and processed to have a composition of 29.3 wt% of copper oxide, 5.9 wt% of titanium oxide, and 64.8 wt% of phosphoric acid, was melted and held at 1250 ° C for 1 hour.
Thereafter, the glass was rapidly cooled in a nitrogen atmosphere to obtain glass. The cooling rate at this time was 1000 ° C./sec. Next, after holding the obtained glass at 480 ° C. for 20 hours, 520
C. for 12 hours to perform heat treatment. Then the resulting glass-ceramics was prepared immersed present invention product 3 days 0.5N-H ₂ SO ₄ aq at room temperature. Powder X of the obtained product of the present invention
When a line diffraction was performed, no Cu ₃ (PO ₄ ) ₂ crystal was detected, and only a CuTi ₂ (PO ₄ ) ₃ crystal was detected. When the specific surface area was measured by the BET method, 46 m ² /
g, and the target characteristics were obtained.

[0006]

Comparative Example 1 Copper oxide 31.9 wt%, titanium oxide 4.2
After adjusting wt% and 63.8 wt% of phosphoric acid, the mixture was kneaded at room temperature using an acrylic resin as a binder. Fill the kneaded material into a metal mold and 1000kg with a hydraulic press
A molded body was obtained at a pressure of / cm ² . Next, this molded body is
Sintering was performed at 300 ° C. for 24 hours to obtain Comparative Example 1. When powder X-ray diffractions of the example and comparative example 1 were performed,
It had only a Ti ₂ (PO ₄ ) ₃ crystal structure. The porosity and specific surface area of Example and Comparative Example 1 were measured. Example Comparative Example 1 Porosity (%) 52 2 Specific surface area (m ² / g) 46 1.

[0007]

Comparative Example 2 Copper oxide 31.9%, titanium oxide 4.2%,
The batch adjusted to 63.9% phosphoric acid was dried at 120 ° C. for 6 hours, and then melted at 1250 ° C. for 1 hour. Thereafter, the glass was rapidly cooled in a nitrogen atmosphere to obtain glass. The cooling rate at this time was 1000 ° C./sec. Next, the obtained glass was kept at 480 ° C. for 20 hours, and then heat-treated at 520 ° C. for 12 hours. Thereafter, the obtained crystallized glass was immersed in 0.5 N—H ₂ SO ₄ aq at room temperature for 3 days to obtain Comparative Example 2. When the powder X-ray diffraction of the example and the comparative example 2 was performed, the example was only the CuTi ₂ (PO ₄ ) ₃ crystal, but the comparative example 2 was several types (T) other than the CuTi ₂ (PO ₄ ) ₃ crystal.
crystal of iO _2, etc.) has been confirmed.

[0008]

Comparative Example 3 After the raw material was adjusted and melted with the same composition as in the example,
Cooling was performed at a temperature lowering rate of 600 ° C./sec. The obtained Comparative Example 3 was subjected to powder X-ray diffraction. As a result, several types of crystals were confirmed instead of glass.

[0009]

Comparative Example 4 Raw material preparation, melting,
After cooling, it was kept at 400 ° C. for 20 hours to obtain Comparative Example 4.
X-ray powder diffraction of Comparative Example 4 obtained here did not confirm any crystals.

[0010]

Comparative Example 5 Raw material preparation, melting,
After cooling, the temperature was maintained at 550 ° C. for 20 hours, and then crystal growth and pickling were carried out in the same manner as in Example to obtain Comparative Example 5. The porosity and the specific surface area of Example and Comparative Example 5 were measured. Example Comparative Example 1 Porosity (%) 52 50 Specific surface area (m ² / g) 46 11.

[0011]

Comparative Example 6 Raw material preparation, melting,
After cooling and generation of crystal nuclei, Comparative Example 6 was obtained by performing an acid treatment without growing crystals. When X-ray powder diffraction of Comparative Example 6 obtained here was CuTi ₂ (PO ₄ ) ₃ , the yield was 2%.

[0012]

Comparative Example 7 Raw material preparation, melting, cooling,
After crystal nucleation and crystal growth, Comparative Example 7 was obtained by immersion in 0.05 N sulfuric acid for 3 days. X-ray powder diffraction of Comparative Example 7 obtained here confirmed not only CuTi ₂ (PO ₄ ) ₃ crystals but also Cu ₃ (PO ₄ ) ₂ crystals. As a result,
According to the present invention, the specific surface area is 10 m ² / g or more, and Cu
It has been found that a porous crystallized glass having only a Ti ₂ (PO ₄ ) ₃ crystal structure can be easily obtained.

[0013]

According to the present invention, CuTi ₂ (PO ₄₎ the effect of the catalytic action and the like can be expected inexpensively and efficiently by ₃ methods a porous crystallized glass having a crystal structure with phase separation of the glass Can be manufactured. Investigation of the antibacterial action shows an effect on algae and the like, and can be expected as an antibacterial material.

Claims (3)

[Claims] 1. 11.8-29.3% by weight of copper oxide, 5.9-10.9% by weight of titanium oxide and 64.8-6% of phosphoric acid
A raw material having a composition of 7.3 wt% is melted,
A porous crystallized glass using a CuTi ₂ (PO ₄ ) ₃ crystal as a skeleton, which is produced by cooling at 0 ° C./sec or more. 2. 450 ° C. using the glass according to claim 1.
Hold for at least 10 hours in the range of
_A method for producing crystallized glass, comprising forming crystal nuclei of ₂ (PO ₄ ) ₃ and Cu ₃ (PO ₄ ) ₂ and then growing the two crystals. 3. The method according to claim 1, wherein the crystallized glass is treated with CuN ₂ (PO ₄ ) ₃ and Cu ₃ (PO ₄ ) ₂ at room temperature using an acid such as hydrochloric acid or sulfuric acid of 0.1 N or more. C 3 characterized by having a specific surface area of 10 m ² / g or more by completely eluting and removing Cu ₃ (PO ₄ ) ₂ crystals contained in the crystallized glass.
A method for producing a porous crystallized glass using a uTi ₂ (PO ₄ ) ₃ crystal as a skeleton.