WO2019049905A1 - Method of manufacturing metal oxide-porous body composite, and composite of porous carbon material and metal oxide - Google Patents

Abstract

The present invention relates to a method for manufacturing a metal oxide-porous body composite by causing a metal oxide to be carried in fine pores of a porous body. The method comprises: a step (1) of placing a porous body under reduced pressure and heating the porous body to a decomposition temperature of a metal oxide precursor; a step (2) of intermittently repeatedly supplying the metal oxide precursor to the porous body under reduced pressure and being heated to cause a decomposed material of the precursor to become precipitated in the fine pores of the porous body; and, after step (2), a step (3) of preparing a metal oxide-porous body composite by heating the porous body, with the precursor and/or the decomposed material thereof having been precipitated in the fine pores, under inert atmosphere and at a temperature higher than in step (1) and (2). With the method, it becomes possible to relatively easily prepare a composite of a porous carbon and a metal oxide in which the metal oxide is uniformly precipitated in the interior of a nanostructure. The present invention relates to a composite of a porous carbon material and a metal oxide in which the metal oxide is partly or entirely present in the fine pores of the porous carbon material. The composite is a composite of a porous carbon and a metal oxide in which the metal oxide is precipitated uniformly in the interior of a carbon nanostructure.

Description

Method of producing metal oxide-porous composite and composite of porous carbon material and metal oxide

The present invention relates to a method for producing a metal oxide-porous composite and a composite of a porous carbon material and a metal oxide.
This application claims the priority of Japanese Patent Application No. 2017-170669 filed on September 5, 2017, the entire description of which is incorporated herein by reference in particular.

Titanium dioxide (TiO ₂ ) is expected to be used as a negative electrode active material of next-generation lithium ion capacitors because the electrolyte can be charged and discharged at a stable potential. However, since titanium dioxide is poor in conductivity, complexation with a conductive substance such as carbon and the like at the nano level has been studied for use as an electrode (patent documents 1 to 3, non-patent document 1).

Patent Document 1: Japanese Patent Application Publication No. 2008-147612 Patent Document 2: Japanese Patent Application Publication No. 2016-538709 Patent Document 3: Japanese Patent Application Publication No. 2016-518023

Non-patent document 1: H.P. Sohn et al., RSC Adv. 2016, 6, 39484-39491
The entire disclosures of Patent Documents 1 to 3 and Non-Patent Document 1 are specifically incorporated herein by reference.

In Patent Document 1 and Non-patent Document 1, a precursor of lithium titanate or titanium oxide is complexed with a carbon material by a wet method to complex titanium oxide and the carbon material. However, in the wet method, it is difficult to composite titanium oxide uniformly to the inside of the nano-structure of the pores of the carbon material.

The problem to be solved in the present invention is to relatively easily prepare a composite of porous carbon and metal oxide in which metal oxide such as titanium dioxide is uniformly deposited to the inside of the complex carbon material nanostructure. It is an object of the present invention to provide a method which can be done and to solve this problem. Furthermore, another object of the present invention is to provide a composite of porous carbon and metal oxide in which metal oxide such as titanium dioxide is uniformly deposited to the inside of complicated carbon nanostructure.

The present inventors can provide a low-cost, mass-producible method if metal oxides such as titanium oxide can be complexed by a vapor phase method to an inexpensive carbon material having a nano structure such as porous carbon. I thought. However, for that purpose, it is necessary to use a metal-containing compound such as a gasifiable titanium compound. For example, in the case of a titanium compound, the gasified titanium compound is often highly reactive and has a low vapor pressure. Therefore, it has been difficult to deposit metal oxides such as titanium oxide uniformly to the inside of complicated carbon nanostructures in the existing gas phase process.

We have developed a new method. In this method, the reaction tube provided with porous carbon is heated under reduced pressure, and the liquid of the titanium compound is instantaneously evaporated by introducing it in the form of a pulse, and can not be obtained by a general flow type source gas introduction method A high concentration of titanium compound vapor is generated near the porous carbon. The pressure difference inside and outside the pore becomes a driving force, and this vapor diffuses smoothly into the deaerated pore, thermally decomposing due to heat conduction from the pore wall, and the decomposition product of the titanium compound precipitates in the pore . Since the excess gas is degassed (exhausted) from the reaction tube, precipitation of decomposition products of the titanium compound out of the pores is relatively small. By repeating this operation any number of times, it is possible to control the deposition amount of the decomposition product of the titanium compound. Thereafter, the porous carbon on which the decomposition product of the titanium compound is precipitated is heated at a higher temperature in an inert atmosphere to release the organic group remaining in the decomposition product of the titanium compound, and the crystallinity By raising it, for example, it becomes anatase type titanium dioxide. It was confirmed that the resulting composite was a uniform dispersion of nanolevel titanium dioxide in carbon pores. Furthermore, using the same method, it was confirmed that a composite in which oxides of metals other than titanium were uniformly dispersed at the nano level in carbon pores was obtained, and the method of the present invention was completed.

Furthermore, the composite obtained by the method of the present invention is one in which metal oxides such as titanium dioxide at nano level are uniformly dispersed in carbon pores. Therefore, in the case of a composite with a metal oxide used as an electrode active material such as titanium dioxide and tin oxide, it is found that there is a sufficient conductive path to the metal oxide, which is a material capable of providing high electrode characteristics. The Furthermore, in the case of a complex with a metal oxide such as vanadium oxide used as a catalyst, the metal oxide is uniformly dispersed at the nano level in carbon pores, and high activity as a catalyst is expected. It found and completed the complex of the present invention.

The present invention is as follows.
[1]
A method for producing a metal oxide-porous composite by supporting a metal oxide in pores of a porous body, comprising the steps of:
Placing the porous body under reduced pressure and heating to the decomposition temperature of the metal oxide precursor (1),
Step (2) of intermittently and repeatedly supplying a liquid metal oxide precursor to a porous body under reduced pressure and under heating, and depositing a decomposition product of the precursor in pores of the porous body, and a step After intermittent repetitive supply in (2), the porous body in which the precursor and / or the decomposition product thereof is precipitated in the pores is heated at a temperature higher than in steps (1) and (2) under reduced pressure or an inert atmosphere. And preparing a metal oxide-porous composite (3),
Said method.
[2]
The manufacturing method according to [1], wherein the number of intermittent repetitive supply in the step (2) is in the range of 10 to 1000 times.
[3]
The intermittent repetitive supply in step (2) consists of repetition of precursor supply time and precursor supply stop time, and the precursor supply time is in the range of 0.01 to 2 seconds, precursor supply stop time Is a range of 1 to 600 seconds, [1] or [2].
[4]
The manufacturing method according to any one of [1] to [3], wherein the reduced pressure in the steps (1), (2) and (3) is in the range of 0.1 hPa (10 Pa) to 1 kPa (1000 Pa).
[5]
The production method according to any one of [1] to [4], wherein the precursor is a metal alkoxide or a metal chloride.
[6]
The production method according to any one of [1] to [5], wherein the amount of the metal oxide supported based on the metal oxide-porous composite is in the range of 1 to 90% by mass.
[7]
The manufacturing method according to any one of [1] to [6], wherein the metal of the metal oxide is at least one selected from Ti, Si, Ni, V, Sn, Zr, Ta, and Ge.
[8]
The porous body according to any one of [1] to [7], wherein the pore volume is in the range of 0.1 to 10 cm ³ (g-carbon) ^-1 and the average pore diameter is in the range of 1 to 500 nm Manufacturing method.
[9]
The method according to any one of [1] to [8], wherein the porous body is a porous carbon material.
[10]
A composite of a porous carbon material and a metal oxide,
The above complex, wherein a part or all of the metal oxide is present in the pores of the porous carbon material.
[11]
The porous carbon material has a pore volume in the range of 0.1 to 10 cm ³ (g-carbon) ^-1 , an average pore diameter in the range of 1 to 500 nm, and a metal oxide based on the complex The complex according to [10], wherein the loading amount of is in the range of 1 to 90% by mass.
[12]
The complex according to [10] or [11], wherein the metal of the metal oxide is at least one selected from Ti, Si, Ni, V, Sn, Zr, Ta, and Ge.
[13]
The complex according to [10] or [11], wherein the metal oxide is anatase type titanium dioxide.
[14]
The composite according to any one of [10] to [13], which is used as a negative electrode material.
[15]
The composite according to [14], which is used as a material for a lithium ion capacitor negative electrode.
[16]
The complex according to any one of [10] to [13], which is used as a catalyst.

According to the present invention, it is relatively easy to prepare a composite of porous carbon and metal oxide in which metal oxide such as titanium dioxide is uniformly deposited to the inside of the complex carbon material nanostructure. it can. Furthermore, according to the present invention, it is possible to provide a composite of porous carbon and metal oxide in which metal oxide is uniformly deposited to the inside of a complex carbon nanostructure. When the metal oxide is titanium dioxide, tin dioxide or the like, this complex has high electrode properties, and when the metal oxide is vanadium oxide, titanium dioxide or the like, this complex has excellent catalytic activity.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic of the VLP-CVD experiment apparatus used in the Example is shown. BRIEF DESCRIPTION OF THE DRAWINGS The schematic explanatory drawing of the method (depressurized liquid pulse CVD (VLP-CVD) method) of this invention is shown. The measurement results of the electron micrographs and TiO ₂ deposition amount shows the appearance of each complex. The heat processing result of a composite body (CNovel MJ (4) 150) is shown. The change of the product by the difference in pore is shown. The measurement result of the influence of heat processing is shown. Application evaluation: LIC negative electrode characteristics (per TiO ₂ weight) Measurement results are shown. The measurement result of the rate cycle characteristic of Cnovel MJ (4) 150 / TiO ₂ nanocomposite is shown. It shows a TEM image of different TiO ₂ / C nanocomposite of CVD conditions in Reference Examples 1 and 2. Showing the electrode characteristics of different TiO ₂ / C nanocomposite of CVD conditions in Reference Examples 1 and 2. The measurement results of the electron micrographs and SnO ₂ precipitation amount shows the appearance of each complex. The measurement results of the rate cycle characteristics of TiO ₂ nanocomposite. The measurement results of the electron micrographs and V ₂ O ₅ deposition amount shows the appearance of the complex.

<Method for producing metal oxide-porous composite>
A first aspect of the present invention is a method of producing a metal oxide-porous composite by supporting a metal oxide in the pores of a porous body. This method is
Placing the porous body under reduced pressure and heating to the decomposition temperature of the metal oxide precursor (1),
Step (2) of intermittently and repeatedly supplying a liquid metal oxide precursor to a porous body under reduced pressure and under heating, and depositing a decomposition product of the precursor in pores of the porous body, and a step After intermittent repetitive supply in (2), the porous body in which the decomposition product of the precursor has been deposited in the pores is heated at a temperature higher than steps (1) and (2) under reduced pressure or an inert atmosphere, Preparing a metal oxide-porous composite (3),
including.

In the present invention, the porous body used for producing the composite is not particularly limited as long as it is a porous substance. From the viewpoint of supporting the metal oxide in the pores of the porous body, the porous body has a pore volume in the range of 0.1 to 10 cm ³ (g-carbon) ^-1 and an average pore diameter of, for example, 1 It can be in the range of ̃500 nm. However, it is not limited to this range. The porous body can be, for example, a porous carbon material.

The porous carbon material is not particularly limited, and examples thereof include microporous carbon, mesoporous carbon, macroporous carbon and the like. In IUPAC, pores of 2 nm or less are defined as micropores, pores of 2 to 50 nm as mesopores, and pores of 50 nm or more as macropores. As mesoporous carbon, for example, CNovel MH, CNovel MJ (4) 030 (manufactured by Toyo Carbon Co., Ltd.) can be mentioned, and as macroporous carbon, for example, C Novel MJ (4) 150 can be mentioned . Examples of microporous carbon include A-BAC PW15 (manufactured by Kureha Co., Ltd.) which is spherical activated carbon. In the present invention, carbon having pores of about 50 nm is referred to as meso-macroporous carbon, and examples of meso-macroporous carbon include carbon gel. Examples of the carbon gel include meso-macroporous carbon obtained by heating (for example, 1000 ° C.) resorcinol-formaldehyde resin (for example, see JP-A-2013-159515). Although not a porous carbon material, carbon nanofibers (CNF) can also carry metal oxides on the surface by the method of the present invention. Examples of carbon nanofibers (CNF) include nanofibers produced by a liquid pulse injection method (Japanese Patent Laid-Open No. 2012-246590). It is not the intention limited to these.

The precursor of the metal oxide is a substance that can be liquid at normal pressure (for example, liquid at normal temperature, or solid at normal temperature but liquid when heated) under reduced pressure in step (2) There is no particular limitation as long as it is a metal-containing compound that can be present as a gas phase by vaporization at. The metal contained in the precursor may be, for example, at least one of Ti, Si, Ni, V, Sn, Zr, Ta, and Ge. The precursor of the metal oxide can be, for example, a metal alkoxide or a metal chloride. Metal alkoxides and metal chlorides can be alkoxides or chlorides of these metals. The metal oxide of the complex can be, for example, at least one of oxides of Ti, Si, Ni, V, Sn, Zr, Ta, and Ge.

In step (1), the porous body is placed under reduced pressure and heated to the decomposition temperature of the metal oxide precursor. The reduced pressure in the step (1) can be appropriately determined in consideration of the type of porous material, the type of precursor of metal oxide, decomposition temperature, etc. For example, 0.1 hPa (10 Pa) to 1 kPa (1000 Pa) It can be a range. The heating temperature may be a temperature above the decomposition temperature of the precursor, and can be a temperature above the decomposition temperature of the metal alkoxide or metal chloride. Therefore, the temperature of heating can be suitably determined according to the type of precursor. For example, it may be in the range of 100 to 200 ° C., but it is not intended to be limited to this range.

In the step (2), the precursor of the metal oxide is intermittently and repeatedly supplied to the porous body under reduced pressure and under heating to precipitate the precursor and / or the decomposition product thereof in the pores of the porous body. The precipitate may be the case of the precursor alone, the case of both the precursor and the decomposition product thereof, and the case of the decomposition product alone depending on the kind of the precursor and the heating conditions. The reduced pressure in the step (2) can be, for example, in the range of 0.1 hPa (10 Pa) to 1 kPa (1000 Pa) as in the step (1). During the supply stop time of the precursor, the pressure reduction in the system proceeds, but when the precursor is supplied, the precursor is vaporized, and this vaporization temporarily causes a pressure fluctuation. The precursor supplied to the porous body under reduced pressure and heat is vaporized and / or decomposed to increase the pressure of the atmosphere surrounding the porous body, and the increase in pressure causes the vaporized and / or decomposed precursor to become It is presumed that it is easy to be taken into the pores of the porous body. Furthermore, the reduced pressure in the pores due to the reduced pressure at the precursor supply stop time is also presumed to be one of the factors that make it easy for the vaporized and / or decomposed precursor to be taken into the pores of the porous body. The number of times of intermittent repetitive supply in the step (2) is arbitrary and may be appropriately determined so as to prepare a desired complex, but can be, for example, in the range of 10 to 1000 times. However, it is not limited to this range. It is appropriately determined in consideration of the type and amount of porous material, the type and amount of precursor once supplied, the desired complex (the amount of metal oxide deposited), and the like.

The intermittent repetitive supply in step (2) consists of repeating the precursor supply time and the precursor supply stop time. For example, it can be carried out by introducing the precursor in a liquid state little by little at regular intervals, in the form of so-called pulses. The supply time of the precursor can be appropriately determined in consideration of the type of precursor, the supply amount of one time, etc., and can be, for example, in the range of 0.01 to 2 seconds, preferably 0.05 It can be in the range of 1 second. In addition, the supply stop time of the precursor may be appropriately determined in consideration of the degree of pressure reduction, heating temperature, type of precursor, etc., and the deposition rate of the metal oxide in the pores of the porous body, etc. For example, it can be in the range of 1 to 600 seconds, preferably in the range of 10 to 120 seconds. The amount of precursor supplied per time can be appropriately determined in consideration of the type and amount of porous material, the type of precursor, etc. For example, 0.01 to 0.1 mg per 1 g of porous material is a standard. be able to. This range is a guide only, and can be appropriately determined in consideration of the type and amount of porous material, the type of precursor, and the operating conditions (degree of pressure reduction, heating temperature, etc.). In the method of the present invention, the liquid raw material is intermittently supplied under reduced pressure to precipitate oxides, so the method of the present invention is called vacuum liquid pulse CVD (VLP-CVD) method. be able to.

In the step (3), after intermittent repetitive supply in the step (2), the porous body in which the precursor and / or the decomposition product thereof is precipitated in the pores is treated under reduced pressure or under an inert atmosphere, the steps (1) and (2) Heating at a higher temperature to prepare a metal oxide-porous composite. The heating temperature can be appropriately determined according to the type of precursor and the type of metal oxide formed from the precursor, and the organic group in the decomposition product of the precursor precipitated in the pores of the porous body is The temperature can be selected from the temperature which promotes desorption and / or the crystallization of the oxide. The reduced pressure in the step (3) can be, for example, in the range of 0.1 hPa (10 Pa) to 1 kPa (1000 Pa) as in the step (2). The inert containing atmosphere can be, for example, nitrogen, helium, argon. When the metal is titanium, the temperature of the heat treatment is, for example, in the range of 600 to 800 ° C., preferably in the range of 650 to 750 ° C., without degrading the carbon material and containing crystallized titanium oxide. It is preferable from the viewpoint that an oxide-porous composite is obtained. In the case of titanium oxide, there are anatase type, rutile type and the like, but it is preferable to set heating conditions appropriately so as to obtain a desired crystal structure. However, when the porous body is a carbon material, depending on the temperature and the atmosphere, shrinkage of the pores in the carbon material may occur, so the heating atmosphere and temperature are selected in consideration of this point. The heating time can be, for example, about 1 minute to 2 hours. However, it is not the intention limited to this range.

A schematic of the experimental apparatus is shown in FIG. 1 and the operating situation is shown in FIG. As shown in FIG. 1, the experimental apparatus includes a reaction tube for installing a carbon material, a syringe for storing and supplying a precursor which is a raw material liquid on the upstream side of the reaction tube, and intermittent and repetitive supply. And a vacuum pump on the downstream side. An electric furnace for heating is disposed around the reaction tube.

The operation is performed by placing a porous carbon material in a reaction tube, reducing the pressure in the reaction tube with a vacuum pump, and raising the temperature to the thermal decomposition temperature of the precursor to be used using a heating device. Next, liquid precursor is intermittently and repeatedly supplied into the reaction tube while the vacuum pump is continuously operated. By intermittent and repetitive supply, the precursor and / or the decomposition product thereof is precipitated in the pores of the porous body. The precursor and / or the decomposition product thereof enters the pore as a driving force due to the pressure difference (inner <outer) inside and outside the pore and precipitates on the inner surface of the pore. After intermittent repetitive supply, the porous carbon material is heated under an inert atmosphere to release and / or crystallize the organic group in the precursor and / or the decomposition product of the precursor deposited on the inner surface of the pore. Facilitate. FIG. 2 schematically shows a state in which fine particles of TiO ₂ are precipitated on the inner surface of the pore.

The supported amount of the metal oxide based on the metal oxide-porous composite is not particularly limited and can be appropriately determined according to the desired composite, and is, for example, in the range of 1 to 90% by mass. be able to. However, it is not limited to this range.

<Complex of porous carbon material and metal oxide>
A second aspect of the present invention is a composite of a porous carbon material and a metal oxide. In this composite, at least a part of the metal oxide is present in the pores of the porous carbon material. The porous carbon material is the same as that described in the above-mentioned production method. The supported amount of the metal oxide is not particularly limited and can be appropriately determined depending on the desired complex, and can be, for example, in the range of 1 to 90% by mass. The metal of the metal oxide can be, for example, at least one of Ti, Si, Ni, V, Sn, Zr, Ta, and Ge. The complex of the present invention can be anatase type titanium oxide when the metal oxide is titanium oxide.

It is preferable that the composite of the porous carbon material and the metal oxide has pores even after the metal oxide is supported, for example, when used as an electrode material, etc. The composite after supporting the metal oxide The body can have a pore volume, for example, in the range of 0.1 to 10 cm ³ (g-carbon) ⁻¹ and an average pore size in the range of 1 to 500 nm.

The porous carbon material has a pore volume in the range of 0.1 to 10 cm ³ (g-carbon) ^-1 , an average pore diameter in the range of 1 to 500 nm, and a metal oxide based on the complex The loading amount of can be in the range of 1 to 90% by mass. The porous carbon material preferably has a pore volume in the range of 1 to 5 cm ³ (g-carbon) ^-1 , an average pore diameter in the range of 2 to 300 nm, and metal oxide based on the complex. The loading amount of the substance is in the range of 10 to 60% by mass. More preferably, the porous carbon material has a pore volume in the range of 2 to 4 cm ³ (g-carbon) ^-1 , an average pore diameter in the range of 10 to 200 nm, and a metal based on the complex. The amount of oxide supported is in the range of 20 to 50% by mass.

The composite of the present invention in which the metal oxide is anatase type titanium oxide can be used as an electrode material, for example, as a negative electrode material. More specifically, the composite of the present invention is used as a material for a lithium ion capacitor negative electrode.

When the metal oxide is tin oxide SnO ₂ , the conductivity can be improved by nano level compounding with a carbon material. SnO ₂ is expected to be a high capacity negative electrode material for lithium ion batteries because it has about 3 times the theoretical capacity of a general graphite negative electrode.

When the metal oxide is vanadium oxide V ₂ O ₅ , V ₂ O ₅ is known as an organic substance or an oxidation catalyst such as sulfur dioxide. By supporting on a porous carbon material support, metal oxide catalysts such as V ₂ O ₅ are expected to increase the surface area of the catalyst and improve the handling.

Hereinafter, the present invention will be described in more detail based on examples. However, the examples are illustrative of the present invention, and the present invention is not intended to be limited to the examples.

Example 1 Preparation of TiO ₂ -Carbon Complex
1.1 Experimental Device A schematic diagram of the experimental device is shown in FIG. A quartz tube was used as a reaction tube, which was inserted vertically into an electric furnace to perform temperature control. A syringe was inserted from the top of the reaction tube via a solenoid valve, and a vacuum pump was attached to the bottom of the reaction tube. In this device, when the reaction tube is in a degassed state, the pressure difference becomes a driving force by opening the solenoid valve, and the raw material in the syringe is introduced into the reaction tube.

・ Reaction tube (quartz tube)
Inner diameter: 13 mm
Length: 600 mm
Fix the quartz filter at 25 cm from the top, and place this quartz filter at the center of the electric furnace

1.2 Raw materials
Ti source: titanium tetraisopropoxide (Wako Pure Chemical Industries, Ltd.)
Carbon support:
Meso-macroporous carbon carbon gel (GC)
Macroporous carbon C Novel MJ (4) 150 (Toyo Carbon Co., Ltd.)
Mesoporous carbon C Novel MJ (4) 030 (Toyo Carbon Co., Ltd.)
Mesoporous carbon CNovel MH (Toyo Carbon Co., Ltd.)
Microporous carbon A-BAC PW15 (Kureha Corporation)
Nonporous carbon carbon nanofiber (CNF) (reference example)

CG production method (refer to JP 2013-159515A)
reagent
R: Resorcinol (Wako Pure Chemical Industries, Ltd.)
F: Formaldehyde solution (Wako Pure Chemical Industries, Ltd., concentration 36-38%)
C: Sodium carbonate (Wako Pure Chemical Industries, Ltd.)
TBA: t-Butyl alcohol (Wako Pure Chemical Industries, Ltd.)

Water, R, F and C were mixed to prepare a solution of R / C = 1000 mol mol ⁻¹ , R / W = 0.5 mol mol ⁻¹ , R / F = 0.5 mol mol ⁻¹ . After stirring for 2 h with a stirrer, it was allowed to stand for 2 days in an incubator maintained at 30 ° C. and then for 3 days at 60 ° C. It was confirmed that the sample was gelled, and the water in the gel was removed by soaking in an excess amount of TBA for 3 days. After prefreezing, lyophilization was performed for 2 days by degassing with a vacuum pump at −10 ° C. The dried sample was heated to 1000 ° C. at 5 ° C. min ⁻¹ in a nitrogen atmosphere, and carbonized at this temperature for 4 h to obtain CG.

1.3 Experimental operation
(1) Precipitation of TiO ₂
1) Place a carbon sample (about 200 mg) on the quartz filter of the reaction tube.
2) The reaction tube was evacuated by a vacuum pump, and the temperature was raised at a heating rate of 10 ° C. min ^-1 .
3) After confirming that the temperature had been raised to the set temperature (180 ° C.), the solenoid valve open / close program (60 s closed, 0.1 s open) was started to introduce the raw material liquid. The introduction amount under this condition is 100 times (50 ml in total) (50 ml in total) (total 5 ml). By this, the intermittent supply of the raw material was performed.
4) After stopping the vacuum pump, the temperature controller was turned off and the reaction tube was cooled.
5) After confirming cooling to about 100 ° C., the reaction tube was taken out and the product on the quartz filter in the center of the reaction tube was recovered.

(2) Heat treatment of sample
1) The sample on which TiO ₂ was precipitated by the operation of (1) was placed on a ceramic boat and placed in a quartz tube (outside diameter 1 inch, length 60 cm) installed in a horizontal tubular furnace (Asahi Rika Seisakusho, ARF-30K) Introduced in the center of the
2) While flowing nitrogen at 100 mL min ^-1 , the temperature was raised to 700 ° C. at 5 ° C. min ^-1 and maintained at this temperature for 1 h.
3) After cooling to room temperature, the heat-treated sample was recovered from the reaction tube.

2. Evaluation method
2.1 Observation of product The obtained product is a field emission scanning electron microscope (FE-SEM, JSM-6600F; JEOL), a transmission electron microscope (TEM, JEM-2010). Observed by JEOL).
For FE-SEM observation, a carbon tape was attached to a sample stand, and a thin sample was placed thereon. This sample stand was inserted into FE-SEM, and observation was performed at an applied voltage of 15.0 kV.

For TEM observation, the sample was dispersed in ethanol by ultrasonication, and several drops were dropped on a microgrid (Nisshin EM Co., Ltd., 200 mesh Cu), and then dried. The sample grid was inserted into a TEM and observed at an applied voltage of 200 kV.

TiO ₂ content of the measurement TiO ₂ composite sample of 2.2 TiO ₂ content thermogravimetric analysis (TGA, Shimadzu; TGA-50H); was measured by the (DTA-50 DTG, Shimadzu). Place the sample in a platinum cell (3 mm in height, 6 mm in diameter) at approximately 10 mg, heat to 800 ° C. at a heating rate of 5 ° C. min ^-1 in an air stream of 20 mL min ^-1 and then 800 ° C. The mixture was kept for 1 h, and after cooling it was recovered and the remaining weight was defined as TiO ₂ weight.

2.3 Crystal structure analysis The crystal structure was analyzed by a powder X-ray diffraction measurement apparatus (sample horizontal-type multipurpose X-ray diffractometer Ultima IV: Rigaku). The detailed measurement conditions are shown in Table 1.

2.4 Analysis of Pore Structure The analysis of the pore structure of the sample was performed using an adsorption measurement apparatus (Microtrack Bell; BELSORP mini II). As pretreatment of the sample before adsorption measurement, the sample was held at 250 ° C. for 4 h under nitrogen flow to remove moisture and the like contained in the sample. The measurement was carried out with an adsorption measurement temperature of -196 ° C. and an adsorbate of N ₂ .

Table 2 shows the change in the amount of precipitated TiO ₂ due to the difference in pore volume. In addition, CNF did not have a pore and was mentioned as a reference example.

In the composite of the present invention, the content of the metal oxide such as titanium oxide can be determined from the weight change when carbon is burned by heating the composite in an oxygen atmosphere. The amount of precipitation of the metal oxide changes depending on the pore structure of the porous carbon used, and the amount of precipitation tends to be larger when the pore diameter and the pore volume are larger (see Table 2).

The appearance of the composite is shown in FIG. FIG. 4 shows XRD and transmission electron micrographs before and after heat treatment. The pore size distribution calculated from the nitrogen adsorption measurement result is shown in FIG. From FIG. 3, scanning electron microscope observation of the obtained composite shows that almost no precipitates are observed on the outer surface of the porous carbon, and FIG. 4 shows that titanium oxide is precipitated in the pores. It was done. This is also confirmed from the pore size distribution shown in FIG. 5 from the fact that the mesopore volume decreases after precipitation, and it is also confirmed that the TiO ₂ deposition amount changes according to the pore volume. According to the transmission electron microscope observation and X-ray diffraction measurement of FIG. 4, TiO ₂ precipitated in an amorphous form becomes a fine anatase crystal having a particle size of 5 nm or less by the heat treatment (improvement of crystallinity), and in porous carbon pores It was observed that they were uniformly supported.

Example 2 Preparation of electrode
1) The sample prepared in Example 1: Carbon black (Denki Kagaku Kogyo Co., Ltd. Denka Black): Polyvinylidene fluoride (Kureha Co., Ltd., KF polymer L # 1120) was weighed so as to be 8: 1: 1. .
2) Add a few drops of 1-methyl-2-pyrrolidone (Wako Pure Chemical Industries, Wako special grade, 99.0%) to the mixture, and use Awatori Neritaro (Sinky, AR-100) for 3 min. Planetary mixing was performed to prepare a slurry.
3) The slurry was placed on a copper foil and stretched to a thickness of 5 mil using a baker-type applicator (Tester Co., Ltd., SA-201).
4) The copper foil coated with the slurry was dried in air at 80 ° C for 1 h with a hot plate (As One Corp., NINOS ND-2), and cut into a circle with an electrode punching device (Hozumi, 16 mm in diameter) .
5) The manufactured electrode was vacuum-dried at 120 ° C. for 10 h in a glove box pass box, and then placed in an Ar atmosphere glove box.
6) Assembled the tripolar cell in the glove box.

Used reagents and materials Counter electrode and reference electrode: Lithium metal (Honjo Metal Co., Ltd., 0.2 mm thick)
Separator: CELGARD 2400, Polypore Co., Ltd., Cut into a diameter of 24 mm and use electrolyte: LiPF ₆ 1 mol / L EC: DEC (1: 1 v / v%), Kishida Chemical Co., Ltd.
Measurement cell: Tripolar cell, Toyo System Co., Ltd.

Charge / discharge measurement The assembled three-pole cell is connected to a battery charge / discharge device (Hokuto Denko Co., Ltd., HJ-1010mSM8 (s)), and 1.0 to 2.5 V (vs. Li / Li) in an incubator maintained at 25 ° C. ^The constant current charge / discharge measurement was performed in the potential range of ( ⁺ ).

The results of the electrochemical evaluation are shown in FIGS. As shown in FIG. 6, it can be seen that the heat treatment in the nitrogen atmosphere performed in Example 1 improves the discharge capacity. From the electrode characterization of composites using various porous carbons, composites prepared from mesoporous carbon and macroporous carbon fully utilize the discharge capacity of TiO _{2 and} are around 200 mAh / g per TiO ₂ weight. capacity is obtained (Fig. 7), also found to be excellent high-speed charge-discharge characteristics, it was confirmed TiO ₂ in the complex that has sufficient conductivity path. The sample with larger pore size showed higher rate characteristics. In particular, the composite using macroporous carbon (Cnovel MJ (4) 150 / TiO ₂ nanocomposite) retains a capacity of about 80% even after 10000 cycles, and it is about at a current density as high as 15000 mA / g. From the fact that half the capacity was available (FIG. 8), it was found to have long life and excellent high-speed charge and discharge performance.

The volume calculation method per TiO ₂ weight in FIG. 7 is as follows.

Reference Example 1 (continuous flow CVD)
A carbon sample C Novel MJ (4) 150 (about 200 mg) was placed on a quartz filter of a reaction tube similar to the experimental apparatus used in Example 1, and the temperature in the reaction tube was raised to a set temperature (180 ° C.) After that, nitrogen was continuously circulated at 100 mL / min from above the reaction tube, and titanium tetraisopropoxide as a raw material liquid was introduced into the reaction tube high temperature part at 50 μL / min for 100 minutes with a microfeeder. Thereafter, heat treatment was performed at 700 ° C. for 1 hour under nitrogen flow of 100 mL / min to recover the product on the quartz filter. The observation of the product and the measurement of the TiO ₂ content were carried out in the same manner as in 2. Evaluation method of Example 1. The TEM photograph and the supported amount (content) of TiO _2- are shown in FIG. 9 (A). As a comparison, FIG. 9 (C) shows the TiO ₂ -carbon material composite of the present invention prepared by the VLP-CVD of FIG. 4 (a). The TEM photograph shows that the particle size of TiO ₂ is large (10 to 20 nm) and agglomerated.

Reference Example 2 (Decompression Continuous Introduction CVD)
A carbon sample C Novel MJ (4) 150 (about 200 mg) was placed on a quartz filter of a reaction tube similar to the experimental apparatus used in Example 1, and the temperature in the reaction tube was raised to a set temperature (180 ° C.) Thereafter, the reaction tube was degassed with a vacuum pump from below, and titanium tetraisopropoxide as a raw material solution was introduced into the reaction tube high temperature part at 50 μL / min for 100 minutes with a microfeeder. Thereafter, heat treatment was performed at 700 ° C. for 1 hour under continuous nitrogen flow of 100 mL / min to recover the product on the quartz filter. The observation of the product and the measurement of the TiO ₂ content were carried out in the same manner as in 2. Evaluation method of Example 1. The TEM photograph and the supported amount (content) of TiO _2- are shown in FIG. 9 (B). As a comparison, FIG. 9 (C) shows the TiO ₂ -carbon material composite of the present invention prepared by the VLP-CVD of FIG. 4 (a). The TEM photograph shows that the particle size of TiO ₂ is large (10 to 20 nm) and agglomerated.

A comparison of TEM photographs of reference examples 1 and 2 and example 1 (FIG. 4 (a)) shows that the general CVD method shown in reference examples 1 and 2 supports minute TiO ₂ nanoparticles in pores. Although it is difficult, it is understood that TiO ₂ nanoparticles with a particle diameter of several nm can be supported in the pores of the carbon material by using the method of the present invention.

Reference Example 3 (charge / discharge measurement)
An electrode was produced in the same manner as in Example 2 using the TiO ₂ -carbon material composite prepared in Reference Examples 1 and 2, and constant current charge / discharge measurement was performed under the same conditions as in Example 2. FIG. 10A shows a charge / discharge curve, and FIG. 10B shows a rate characteristic evaluation result. These results, compared to Reference Example 1 and TiO ₂ / C nanocomposite obtained in typical continuous introduction CVD shown in 2, TiO ₂ / C nanocomposite of the present invention prepared in VLP-CVD method It can be understood that high capacity and high speed charge and discharge are possible.

Example 3
3.1 Experimental operation
(1) Precipitation of SnO ₂
1) Place a carbon sample C Novel MJ (4) 030 or C Novel MJ (4) 150 (about 200 mg) on a quartz filter of a reaction tube.
2) The reaction tube was evacuated by a vacuum pump to a pressure of 500 Pa, and the temperature of the reaction tube was raised at a temperature rising rate of 10 ° C. min ^-1 .
3) After confirming that the temperature has been raised to the set temperature (80 ° C or 100 ° C), start the solenoid valve open / close program (60s closed, 0.1s open) to start tin (IV) isopropoxy which is the raw material liquid Introduced the de The introduction amount under this condition is 50 μL, 50 times or 100 times (total 2.5 mL or 5 mL) at one time.
4) After stopping the vacuum pump, the temperature controller was turned off and the reaction tube was cooled.
5) After confirming cooling to about 100 ° C., the reaction tube was taken out and the product on the quartz filter in the center of the reaction tube was recovered.

(2) Heat treatment of sample
1) The sample on which SnO ₂ was deposited by the operation of (1) was placed on a ceramic boat and placed in a quartz tube (outside diameter 1 inch, length 60 cm) installed in a horizontal tubular furnace (Asahi Rika Seisakusho, ARF-30K) Introduced in the center of the
2) While flowing nitrogen at 100 mL min ^-1 , the temperature was raised to 700 ° C. at 5 ° C. min ^-1 and maintained at this temperature for 1 h.
3) After cooling to room temperature, the heat-treated sample was recovered from the reaction tube.

3.2 Evaluation method The observation of the product and the measurement of the SnO ₂ content were carried out in the same manner as in 2. Evaluation method of Example 1. The TEM photograph of the SnO ₂ -carbon material composite and the supported amount (content) of SnO _2- obtained with the temperature rising set temperature set to 100 ° C. and the introduction amount of tin (IV) isopropoxide being a total of 5 mL. It is shown in FIG. A composite was obtained in which minute SnO ₂ nanoparticles of 10 nm or less were uniformly supported in the pores of (A) porous carbon having a pore diameter of 150 nm and (B) porous carbon having a diameter of 30 nm.

3.3 charge and discharge measurement
An electrode was produced in the same manner as in Example 2 using the SnO ₂ -carbon material composite prepared in 3.1, and constant current charge / discharge measurement was performed under the same conditions as in Example 2. FIG. 12 shows the result of the electrochemical evaluation. (A) is the charge-discharge characteristics of the composite obtained from different porous carbons (reaction temperature: 100 ° C., raw material introduction amount: 5 mL), and (B) is the charge-discharge of the composite obtained at different reaction temperature It is a characteristic (porous carbon: CNovel 150, raw material introduction amount: 2.5 mL). The result of (A) shows that, when using CNovel 150 having a large pore diameter, which can utilize the capacity of SnO ₂ in any of the complexes, as the carrier, high capacity and high rate characteristics are obtained despite the small amount of SnO ₂ supported. Indicates that there is. The result of (B) indicates that the reaction temperature is higher at 80 ° C. than at 100 ° C., and a high capacity can be obtained. As shown in (A) ((N), it can be seen that the heat treatment in a nitrogen atmosphere performed in Example 1 improves the discharge capacity. According to the VLP-CVD method of the present invention, the SnO ₂ nanoparticles are also supported It is possible that the SnO ₂ nanoparticle-supported carbon material composite can be expected to be used as a high capacity negative electrode material of a lithium ion battery.

Example 4
4.1 Experimental operation
(1) Precipitation of V ₂ O ₅
1) Place the carbon sample C Novel MJ (4) 150 (about 200 mg) on the quartz filter of the reaction tube.
2) The reaction tube was evacuated by a vacuum pump to a pressure of 500 Pa, and the temperature of the reaction tube was raised at a temperature rising rate of 10 ° C. min ^-1 .
3) After confirming that the temperature has been raised to the set temperature (100 ° C), start the solenoid valve open / close program (60 s closed, 0.1 s open) to start vanadium (V) oxytriisopropoxide as the raw material liquid Introduced. The amount introduced under this condition is 50 μL at a time, for a total of 1 mL 20 times.
4) After stopping the vacuum pump, the temperature controller was turned off and the reaction tube was cooled.
5) After confirming cooling to about 100 ° C., the reaction tube was taken out, and the product on the quartz filter in the center of the reaction tube was recovered.

(2) Heat treatment of sample
1) A sample obtained by depositing V ₂ O ₅ by the operation of (1) is placed on a ceramic boat, and a quartz tube (outer diameter 1 inch, length 60 cm) installed in a horizontal tubular furnace (Asahi Rika Seisakusho, ARF-30K) Introduced in the center of the
2) While flowing nitrogen at 100 mL min ^-1 , the temperature was raised to 700 ° C. at 5 ° C. min ^-1 and maintained at this temperature for 1 h.
3) After cooling to room temperature, the heat-treated sample was recovered from the reaction tube.

4.2 Evaluation method The observation of the product and the measurement of the V ₂ O ₅ content were carried out in the same manner as in 2. Evaluation method of Example 1. The TEM photograph of the obtained SnO ₂ -carbon material composite and the supported amount (content) of V ₂ O _5- are shown in FIG. A composite was obtained in which minute V ₂ O ₅ nanoparticles of 10 nm or less were uniformly supported in the pores of porous carbon with a pore diameter of 150 nm. The resulting complex is expected to be used as a catalyst.

The present invention is useful in the field of porous-metal precursor composites and in the field of electrode materials of lithium ion capacitors.

Claims (16)

1. A method for producing a metal oxide-porous composite by supporting a metal oxide in pores of a porous body, comprising the steps of:
   Placing the porous body under reduced pressure and heating to the decomposition temperature of the metal oxide precursor (1),
   Step (2) of intermittently and repeatedly supplying a liquid metal oxide precursor to a porous body under reduced pressure and under heating, and depositing a decomposition product of the precursor in pores of the porous body, and a step After intermittent repetitive supply in (2), the porous body in which the precursor and / or the decomposition product thereof is precipitated in the pores is heated at a temperature higher than in steps (1) and (2) under reduced pressure or an inert atmosphere. And preparing a metal oxide-porous composite (3),
   Said method.
2. The production method according to claim 1, wherein the number of intermittent repetitive feedings in step (2) is in the range of 10 to 1000 times.
3. The intermittent repetitive supply in step (2) consists of repetition of precursor supply time and precursor supply stop time, and the precursor supply time is in the range of 0.01 to 2 seconds, precursor supply stop time The method according to claim 1 or 2, wherein is in the range of 1 to 600 seconds.
4. The method according to any one of claims 1 to 3, wherein the reduced pressure in the steps (1), (2) and (3) is in the range of 0.1 hPa (10 Pa) to 1 kPa (1000 Pa).
5. The method according to any one of claims 1 to 4, wherein the precursor is a metal alkoxide or a metal chloride.
6. The production method according to any one of claims 1 to 5, wherein the loading amount of the metal oxide based on the metal oxide-porous composite is in the range of 1 to 90% by mass.
7. The method according to any one of claims 1 to 6, wherein the metal of the metal oxide is at least one selected from Ti, Si, Ni, V, Sn, Zr, Ta, and Ge.
8. The production according to any one of claims 1 to 7, wherein the porous body has a pore volume in the range of 0.1 to 10 cm ³ (g-carbon) ^-1 and an average pore diameter in the range of 1 to 500 nm. Method.
9. The method according to any one of claims 1 to 8, wherein the porous body is a porous carbon material.
10. A composite of a porous carbon material and a metal oxide,
    The above complex, wherein a part or all of the metal oxide is present in the pores of the porous carbon material.
11. The porous carbon material has a pore volume in the range of 0.1 to 10 cm ³ (g-carbon) ^-1 , an average pore diameter in the range of 1 to 500 nm, and a metal oxide based on the complex The complex according to claim 10, wherein the loading amount of is in the range of 1 to 90% by mass.
12. The composite according to claim 10, wherein the metal of the metal oxide is at least one selected from Ti, Si, Ni, V, Sn, Zr, Ta, and Ge.
13. The complex according to claim 10 or 11, wherein the metal oxide is anatase type titanium dioxide.
14. The composite according to any one of claims 10 to 13, which is used as a negative electrode material.
15. The composite according to claim 14, which is used as a material for a lithium ion capacitor negative electrode.
16. The complex according to any one of claims 10 to 13, which is used as a catalyst.

Images