JP2013199406A - Lower order titanium oxide, and method for producing the same - Google Patents
Lower order titanium oxide, and method for producing the same Download PDFInfo
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Description
本発明は、光触媒用途、酸素吸収剤用途などに有用な低次酸化チタンおよびその製造方法に関する。 The present invention relates to low-order titanium oxide useful for photocatalyst use, oxygen absorbent use, and the like, and a method for producing the same.
酸化チタンは、隠ぺい力、耐候性に優れた白色顔料として永らく用いられてきたが、近年では光触媒としての機能が注目を集めている。光触媒は、紫外線が表面に照射されたときに発生するラジカル物質（ヒドロキシラジカル、スーパーオキシドアニオン）により、有害物質（アルデヒド類等）の吸着、酸化分解、悪臭物質（悪臭防止法で規制されている物質）の消臭分解、防汚、滅菌などの機能を持つ物質である。近年、この光触媒をコートすることにより、これらの機能を利用する展開が図られている。多くの金属酸化物が光触媒として利用できるが、これらの中でも活性が高いアナターゼ型酸化チタンが多く利用されている。 Titanium oxide has long been used as a white pigment having excellent hiding power and weather resistance, but in recent years, its function as a photocatalyst has attracted attention. Photocatalysts are regulated by the adsorption of harmful substances (aldehydes, etc.), oxidative decomposition, and offensive odor substances (Odor Control Law) by radical substances (hydroxy radicals, superoxide anions) that are generated when the surface is irradiated with ultraviolet rays The substance has functions such as deodorizing decomposition, antifouling, and sterilization. In recent years, the coating of this photocatalyst has been developed to utilize these functions. Many metal oxides can be used as photocatalysts, and among these, anatase-type titanium oxide having high activity is often used.
Ｔｉ２Ｏ３等に代表される低次酸化チタン（組成式：ＴｉＯｘ（式中のｘは、０＜ｘ＜２の範囲である））は、上記した光触媒用途（特許文献１参照）に加えて、黒色顔料用途（特許文献２参照）、酸素吸収剤用途（特許文献３参照）などへの利用が検討されている。また、帯電防止剤用途（非特許文献１参照）、二次電池電極材料用途（特許文献４参照）などの導電性材料用途が検討されている。 Low-order titanium oxide represented by Ti 2 O 3 and the like (compositional formula: TiO x (where x is in the range of 0 <x <2)) is used for the above-described photocatalyst use (see Patent Document 1). In addition, utilization for black pigment applications (see Patent Document 2), oxygen absorbent applications (see Patent Document 3), and the like has been studied. In addition, conductive material applications such as antistatic agent applications (see Non-Patent Document 1) and secondary battery electrode material applications (see Patent Document 4) are being studied.
このうち、酸素吸収剤用途、光触媒用途などでは比表面積を大きくすることが望ましい。 Of these, it is desirable to increase the specific surface area for oxygen absorber applications, photocatalyst applications, and the like.
低次酸化チタンの製造方法として、二酸化チタンを還元する方法が知られている。また、チタン含有電極を含む２つの電極を用いて水中にプラズマ放電することで低次酸化チタンが生成することも開示されている（非特許文献２、特許文献５参照）。 As a method for producing low-order titanium oxide, a method for reducing titanium dioxide is known. Moreover, it is also disclosed that low-order titanium oxide is generated by performing plasma discharge in water using two electrodes including a titanium-containing electrode (see Non-Patent Document 2 and Patent Document 5).
このうち、二酸化チタンを還元する方法では、二酸化チタンの粒子径や、粒子表面と粒子内部とで還元反応に要する時間や、酸化数が異なる場合があり、均一な低次酸化チタンを得るのが困難である。また還元反応の条件によっては、粒子が凝集する場合があり、小粒径の低次酸化チタンを得るのが困難であることから、低次酸化チタンの比表面積を大きくすることも困難である。 Among these, in the method of reducing titanium dioxide, the particle diameter of titanium dioxide, the time required for the reduction reaction between the particle surface and the inside of the particle, and the oxidation number may differ, and it is possible to obtain uniform low-order titanium oxide. Have difficulty. Depending on the conditions of the reduction reaction, the particles may agglomerate, and it is difficult to obtain a low-order titanium oxide having a small particle size. Therefore, it is difficult to increase the specific surface area of the low-order titanium oxide.
またプラズマ放電による方法では、得られる低次酸化チタンの比表面積を大きくする方法は知られていない。 In addition, as a method using plasma discharge, there is no known method for increasing the specific surface area of the obtained low-order titanium oxide.
本発明の目的は、上記のような従来技術の問題点に鑑みて、５０ｍ２/ｇ以上の比表面積を有する低次酸化チタンを工業的規模で安定的に製造できる方法を提供することにある。 An object of the present invention is to provide a method capable of stably producing low-order titanium oxide having a specific surface area of 50 m 2 / g or more on an industrial scale in view of the problems of the prior art as described above. .
上記目的を実現するため、本発明は、
［１］組成式ＴｉＯｘ（式中ｘは、１．５＜ｘ＜２の範囲である）で表され、かつ比表面積が５０ｍ２／ｇ以上の低次酸化チタン；
［２］少なくとも一方がチタン含有電極である二つの電極間に水系媒体を流通させつつ、前記二つの電極から前記水系媒体にプラズマ放電する工程を含む、低次酸化チタンの製造方法；および
［３］前記二つの電極の少なくとも一方が中空部を有し、前記水系媒体を前記中空部を通じて注入及び／又は吸引する、［２］の低次酸化チタンの製造方法
を提供する。
In order to achieve the above object, the present invention provides:
[1] Low-order titanium oxide represented by a composition formula TiO x (wherein x is in a range of 1.5 <x <2) and having a specific surface area of 50 m 2 / g or more;
[2] A method for producing low-order titanium oxide, comprising a step of plasma discharging from the two electrodes to the aqueous medium while flowing the aqueous medium between two electrodes, at least one of which is a titanium-containing electrode; and [3 The method for producing low-order titanium oxide according to [2], wherein at least one of the two electrodes has a hollow portion, and the aqueous medium is injected and / or sucked through the hollow portion.
本発明で得られる低次酸化チタンは、５０ｍ２/ｇ以上の高い比表面積を有するので、酸素吸収剤用途、光触媒用途などに有用である。 Since the low-order titanium oxide obtained in the present invention has a high specific surface area of 50 m 2 / g or more, it is useful for oxygen absorbent applications, photocatalyst applications, and the like.
本発明の製造方法により、かかる低次酸化チタンを工業的規模で安定的に製造することができる。 Such a low-order titanium oxide can be stably produced on an industrial scale by the production method of the present invention.
低次酸化チタンの組成式ＴｉＯｘにおけるｘは、１．５＜ｘ＜２の範囲であり、１．６＜ｘ＜１．９の範囲であることが好ましい。ｘは低次酸化チタンを充分に乾燥した後、熱重量分析装置に入れ、大気中で５℃／分の昇温速度で１０００℃まで昇温することで二酸化チタンに酸化し、かかる酸化に伴う質量増加から求められる。なお、上記熱重量分析は、無作為にサンプリングした０．００１ｇ以上、好ましくは０．０１ｇ以上の低次酸化チタンを用いて測定する。また、低次酸化チタンは粒子状の組成物であることが好ましい。 X in the composition formula TiO x of the low-order titanium oxide is in the range of 1.5 <x <2, and preferably in the range of 1.6 <x <1.9. x, after sufficiently drying low-order titanium oxide, puts it in a thermogravimetric analyzer and oxidizes it to titanium dioxide by raising the temperature to 1000 ° C. at a temperature rising rate of 5 ° C./min in the atmosphere. Obtained from mass increase. In addition, the said thermogravimetric analysis is measured using 0.001 g or more of preferably randomly sampled low-order titanium oxide of 0.01 g or more. The low-order titanium oxide is preferably a particulate composition.
本発明の低次酸化チタンの比表面積は５０ｍ２／ｇ以上であり、７０ｍ２／ｇ以上であることがより好ましく、９０ｍ２／ｇ以上であることがさらに好ましい。比表面積が５０ｍ２／ｇ未満であると、低次酸化チタンを担持担体とした場合、担持物粒径が大きくなり、担持物性能が発揮できないことや、吸着材として使用する場合には、吸着量が小さくなるなど、実用上の課題の原因となる。本発明の低次酸化チタンの比表面積の上限値は特に制限されないが、通常２５０ｍ２／ｇ以下であり、より典型的には２００ｍ２／ｇ以下である。なお、低次酸化チタンの比表面積は、無作為にサンプリングした０．００１ｇ以上、好ましくは０．０１ｇ以上の低次酸化チタンを用いて吸着等温線を作製し、ＢＥＴ法によって解析することにより求められる。 The specific surface area of the low-order titanium oxide of the present invention is 50 m 2 / g or more, more preferably 70m 2 / g or more, and still more preferably 90m 2 / g or more. When the specific surface area is less than 50 m 2 / g, when the low-order titanium oxide is used as a carrier, the particle size of the carrier increases, and the performance of the carrier cannot be exhibited. This causes a practical problem such as a small amount. Although the upper limit of the specific surface area of the low-order titanium oxide of the present invention is not particularly limited, it is usually 250 m 2 / g or less, more typically 200 m 2 / g or less. The specific surface area of low-order titanium oxide is determined by preparing an adsorption isotherm using 0.001 g or more, preferably 0.01 g or more of low-order titanium oxide sampled at random, and analyzing it by the BET method. It is done.
本発明の低次酸化チタンは本発明の低次酸化チタンの製造方法によって、工業的規模で安定的に製造することができる。 The low-order titanium oxide of the present invention can be stably produced on an industrial scale by the method for producing low-order titanium oxide of the present invention.
本発明で用いる低次酸化チタンは、少なくとも一方がチタン含有電極である二つの電極間で二つの電極間に水系媒体を流通させつつ、前記二つの電極から前記水系媒体にプラズマ放電することにより製造できる。プラズマ放電による低次酸化チタン生成のメカニズムは、水系媒体を挟んで対向した電極間に絶縁破壊電圧を超える電圧を印加することにより生じるプラズマにより溶融した電極中のチタンが水系媒体に放散し、放散したチタンが水と反応すると同時に急冷されて低次酸化チタンが生成すると推定している。二つの電極間に水系媒体を流通させつつ、前記二つの電極から前記水系媒体にプラズマ放電することにより、生成した低次酸化チタンは、水系媒体に分散されて放電場より速やかに排出されるので、小粒径となり、この結果、本発明の触媒中の低次酸化チタンの比表面積が５０ｍ２／ｇ以上となる。 The low-order titanium oxide used in the present invention is produced by performing plasma discharge from the two electrodes to the aqueous medium while flowing the aqueous medium between the two electrodes, at least one of which is a titanium-containing electrode. it can. The mechanism of low-order titanium oxide generation by plasma discharge is that the titanium in the electrode melted by the plasma generated by applying a voltage exceeding the breakdown voltage between the electrodes facing each other across the aqueous medium is diffused to the aqueous medium. It is estimated that the titanium reacted with water and rapidly cooled to produce low-order titanium oxide. Since the aqueous medium is circulated between the two electrodes and plasma discharge is performed from the two electrodes to the aqueous medium, the generated low-order titanium oxide is dispersed in the aqueous medium and quickly discharged from the discharge field. As a result, the specific surface area of the low-order titanium oxide in the catalyst of the present invention is 50 m 2 / g or more.
本発明の製造方法で用いるチタン含有電極の材料としては、金属チタン、チタン合金、酸化チタンが挙げられる。本発明の製造方法において、少なくとも一方の電極材料を、シリコン、錫などの典型金属；ジルコニウム、タングステンなどの遷移金属；などとの異種金属を含むチタン合金とすると、得られる低次酸化チタンに前記異種金属またはその酸化物を含有させることができる。 Examples of the material of the titanium-containing electrode used in the production method of the present invention include metal titanium, titanium alloy, and titanium oxide. In the production method of the present invention, when at least one electrode material is a titanium alloy containing a dissimilar metal such as a typical metal such as silicon or tin; a transition metal such as zirconium or tungsten; A different metal or its oxide can be contained.
電極の形状に特に制限はなく、例えば、棒状、針金状、板状、または中空部を有する形状などが挙げられる。中でも二つの電極間に水系媒体を流通させる観点から、少なくとも一方が中空部を有する形状であることが好ましく、チューブ状などの中空部を有する形状がより好ましい。２つの電極の形状や大きさは互いに異なっていてもよい。 There is no restriction | limiting in particular in the shape of an electrode, For example, the shape etc. which have rod shape, wire shape, plate shape, or a hollow part etc. are mentioned. Among these, from the viewpoint of circulating an aqueous medium between two electrodes, it is preferable that at least one has a shape having a hollow portion, and a shape having a hollow portion such as a tube shape is more preferable. The shapes and sizes of the two electrodes may be different from each other.
水系媒体を流通させる方向は特に制限されないが、水系媒体により排出された低次酸化チタンが放電場に戻ることを抑制するために、二つの電極間を一方向に向けて流通させてもよい。 The direction in which the aqueous medium is circulated is not particularly limited, but the low-order titanium oxide discharged by the aqueous medium may be circulated in one direction between the two electrodes in order to suppress the return to the discharge field.
また、水系媒体を流通させる方法としては、少なくとも一方の電極を、チューブ状などの中空部を有する形状の電極（以下、「中空電極」と称する）として、水系媒体を中空電極の中空部を通じて注入及び／又は吸引することが好ましい。反応器内に設置した中空電極の中空部を通じて外部から水系媒体を注入するか、反応器内の水系媒体を中空電極の中空部を通じて吸引し系外に放出することで、中空電極を中心とした放射状の流れを発生させることができる。また２つの中空電極を用いて、一方の中空電極の中空部を通じて水系媒体を供給し、他方の中空電極の中空部を通じて水系媒体を吸引し、系外に放出してもよい。反応場に低次酸化チタンを残留させない観点から、中空電極の中空部を通じて水系媒体を吸引し、系外に放出することが好ましい。 In addition, as a method of circulating the aqueous medium, at least one of the electrodes is formed as an electrode having a hollow part such as a tube (hereinafter referred to as “hollow electrode”), and the aqueous medium is injected through the hollow part of the hollow electrode. And / or suction. The aqueous medium is injected from the outside through the hollow part of the hollow electrode installed in the reactor, or the aqueous medium in the reactor is sucked through the hollow part of the hollow electrode and discharged out of the system, thereby centering on the hollow electrode. A radial flow can be generated. Alternatively, the two hollow electrodes may be used to supply the aqueous medium through the hollow part of one hollow electrode, suck the aqueous medium through the hollow part of the other hollow electrode, and discharge the aqueous medium out of the system. From the viewpoint of preventing low-order titanium oxide from remaining in the reaction field, it is preferable to suck the aqueous medium through the hollow portion of the hollow electrode and release it outside the system.
水系媒体を流通させる速度は、生成した低次酸化チタンが反応場に滞留しなければ、特に制限はなく、例えば、２つの電極の放電部の最短距離が０．１〜２ｍｍである場合は、１〜２００ｍｌ／分の範囲が好ましく、１０〜１５０ｍｌ／分の範囲がより好ましい。 The speed at which the aqueous medium is circulated is not particularly limited as long as the produced low-order titanium oxide does not stay in the reaction field. For example, when the shortest distance between the discharge portions of the two electrodes is 0.1 to 2 mm, A range of 1 to 200 ml / min is preferable, and a range of 10 to 150 ml / min is more preferable.
本発明の製造方法で用いる水系媒体は、水を５０質量％以上含むことが好ましい。通常、水単独又は水と水溶性有機溶媒との混合液を使用する。水溶性有機溶媒としては、例えばエチレングリコール、１，２−プロピレングリコール、１，３−プロピレングリコール、１，２−ブタンジオール、１，４−ブタンジオールなどのアルキレングリコール；ジエチレングリコール、テトラエチレングリコール、ポリエチレングリコールなどのポリアルキレングリコール；および前記アルキレングリコールまたはポリアルキレングリコールのモノアルキルエーテル（例えばモノメチルエーテル、モノエチルエーテル）等が挙げられる。水は、例えば、イオン交換水等を用いるのが好ましい。水系媒体は、本発明の目的を損なわない範囲であれば水溶性有機溶媒以外の成分を含有していてもよい。例えば、過酸化水素の添加や、水系媒体の温度により、得られる低次酸化チタンの組成を制御することができる。 The aqueous medium used in the production method of the present invention preferably contains 50% by mass or more of water. Usually, water alone or a mixture of water and a water-soluble organic solvent is used. Examples of water-soluble organic solvents include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,4-butanediol and other alkylene glycols; diethylene glycol, tetraethylene glycol, polyethylene And polyalkylene glycols such as glycol; and monoalkyl ethers (for example, monomethyl ether, monoethyl ether) of the alkylene glycol or polyalkylene glycol. For example, ion-exchanged water is preferably used as the water. The aqueous medium may contain components other than the water-soluble organic solvent as long as the object of the present invention is not impaired. For example, the composition of the low-order titanium oxide obtained can be controlled by the addition of hydrogen peroxide and the temperature of the aqueous medium.
水系媒体の使用量に特に制限はないが、発熱を制御できる量であることが好ましい。 Although there is no restriction | limiting in particular in the usage-amount of an aqueous medium, It is preferable that it is the quantity which can control heat_generation | fever.
２つの電極はプラズマ放電する位置（放電部）において２つの電極が最も近接するように配置することが好ましく、２つの電極の放電部の最短距離は、通常０．０１ｍｍ〜３ｍｍであり、好ましくは０．１〜２ｍｍである。またかかる放電部はいずれも水系媒体中にあるように配置する。プラズマ放電のため電極間に印加する電流は、直流電流または交流電流のどちらを用いてもよいが、操作性及び生産安定性の観点から、直流電流を用いることが好ましい。交流電流を用いる場合は、ダイオードを用いて整流してもよい。 The two electrodes are preferably arranged so that the two electrodes are closest to each other at the position (discharge portion) where plasma discharge occurs, and the shortest distance between the discharge portions of the two electrodes is usually 0.01 mm to 3 mm, preferably 0.1 to 2 mm. Further, such discharge parts are arranged so as to be in the aqueous medium. A direct current or an alternating current may be used as the current applied between the electrodes for plasma discharge, but it is preferable to use a direct current from the viewpoint of operability and production stability. When an alternating current is used, rectification may be performed using a diode.
二つの電極間でプラズマ放電する電流に制限はなく、１〜２００Ａの範囲が好ましく、低次酸化チタンの生成量、エネルギー効率の観点から、２〜１５０Ａの範囲がより好ましく、５〜１２０Ａの範囲がさらに好ましい。二つの電極間に印加する電圧に特に制限はないが、２０〜６００Ｖの範囲が好ましく、工業生産性の観点から、６０〜５００Ｖの範囲がより好ましく、８０〜４００Ｖの範囲がさらに好ましい。 There is no restriction | limiting in the electric current which plasma discharges between two electrodes, The range of 1-200A is preferable, The range of 2-150A is more preferable from a viewpoint of the production amount of low order titanium oxide, and energy efficiency, The range of 5-120A Is more preferable. Although there is no restriction | limiting in particular in the voltage applied between two electrodes, the range of 20-600V is preferable, the range of 60-500V is more preferable from a viewpoint of industrial productivity, and the range of 80-400V is further more preferable.
プラズマ放電の方式は、連続プラズマ放電であってもパルスプラズマ放電であっても構わない。プラズマ放電の方式により、生成するプラズマの環境が異なるため、得られる低次酸化チタンの組成分布、粒径分布、結晶形態に変化が起こる。 The plasma discharge method may be continuous plasma discharge or pulsed plasma discharge. Since the environment of the generated plasma differs depending on the plasma discharge method, the composition distribution, particle size distribution, and crystal form of the resulting low-order titanium oxide change.
パルスプラズマ放電を与える場合、放電間隔に特に制限はないが、通常、０．０１マイクロ秒〜１００ミリ秒が好ましく、０．１マイクロ秒〜５０ミリ秒がより好ましい。パルス間隔が短すぎると、生成する低次酸化チタンの分布がばらつく傾向となる。また、長すぎる放電間隔では、低次酸化チタンの生成量が著しく小さくなる傾向となる。 When pulsed plasma discharge is applied, the discharge interval is not particularly limited, but is usually preferably 0.01 microseconds to 100 milliseconds, and more preferably 0.1 microseconds to 50 milliseconds. If the pulse interval is too short, the distribution of the low-order titanium oxide produced tends to vary. Moreover, when the discharge interval is too long, the amount of low-order titanium oxide produced tends to be remarkably reduced.
パルスプラズマ放電１回あたりの放電持続時間は、電圧および電流によっても異なるが、通常１〜２０００マイクロ秒の範囲が好ましく、エネルギー効率の観点から、２〜１０００マイクロ秒の範囲がより好ましい。 The discharge duration per pulsed plasma discharge varies depending on the voltage and current, but is usually preferably in the range of 1 to 2000 microseconds, and more preferably in the range of 2 to 1000 microseconds from the viewpoint of energy efficiency.
パルスプラズマ放電におけるパルス形状としては、正弦波、矩形波、三角波などが挙げられ、エネルギー効率の関連から、矩形波であるのが好ましい。 Examples of the pulse shape in the pulsed plasma discharge include a sine wave, a rectangular wave, a triangular wave, and the like. From the viewpoint of energy efficiency, a rectangular wave is preferable.
プラズマ放電させる際の水系媒体の温度は、１０〜１００℃の範囲が好ましい。１００℃より高いと、水系媒体の蒸気圧が上がり、プラズマ放電が困難となる場合がある。また、１０℃より低いと、水系媒体の粘度が上昇して、反応性が下がるだけでなく、生成する低次酸化チタンの拡散性が低下する場合がある。 The temperature of the aqueous medium during plasma discharge is preferably in the range of 10 to 100 ° C. When the temperature is higher than 100 ° C., the vapor pressure of the aqueous medium increases and plasma discharge may be difficult. On the other hand, when the temperature is lower than 10 ° C., the viscosity of the aqueous medium increases and the reactivity decreases, and the diffusibility of the low-order titanium oxide produced may decrease.
本発明の低次酸化チタンの製造方法は、減圧下、加圧下、常圧下のいずれの状態でも実施できる。安全性、操作性の観点から、窒素、アルゴンなどの不活性ガス雰囲気下で実施することが好ましい。 The method for producing low-order titanium oxide of the present invention can be carried out in any state under reduced pressure, increased pressure, or normal pressure. From the viewpoint of safety and operability, it is preferably carried out in an inert gas atmosphere such as nitrogen or argon.
本発明の製造方法により生成する低次酸化チタンは、水性媒体中に分散した分散体として得られるので、当該分散体を、例えば、ろ過、遠心分離、水洗、乾燥することで、本発明の低次酸化チタンを単離できる。 Since the low-order titanium oxide produced by the production method of the present invention is obtained as a dispersion dispersed in an aqueous medium, the dispersion can be obtained by, for example, filtering, centrifuging, washing with water, and drying. Titanium suboxide can be isolated.
以下、実施例により本発明を詳細に説明するが、本発明はかかる実施例により何ら制限されない。 EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not restrict | limited at all by this Example.
下記の実施例１、２及び比較例１において、低次酸化チタンの組成式ＴｉＯｘにおけるｘの値は、低次酸化チタンを充分に乾燥した後、熱重量分析装置に入れ、大気中で５℃／分の昇温速度で１０００℃まで昇温することで二酸化チタンに酸化し、かかる酸化に伴う質量増加から求めた。
低次酸化チタンの比表面積は、窒素ガスの吸着等温線を測定し、ＢＥＴ法で解析することにより求めた。具体的には、約０．１gの試料を入れたサンプル管を、減圧下、２００℃、１２時間乾燥させ、乾燥後の質量を測定した。次いで試料を比表面積計（日本ベル（株）製、BELSORP-miniII）に装着して液体窒素に浸漬し、冷却完了後、吸着ガスとして窒素を用い、吸着等温線を測定した。得られた吸着等温線をＢＥＴ等温線に変換し、ＢＥＴ等温線の近似直線の傾きと質量から比表面積を算出した。
In the following Examples 1 and 2 and Comparative Example 1, the value of x in the composition formula TiO x of the low-order titanium oxide is 5% in the atmosphere after the low-order titanium oxide is sufficiently dried and then put into a thermogravimetric analyzer. It was oxidized to titanium dioxide by raising the temperature to 1000 ° C. at a temperature increase rate of ° C./min, and obtained from the mass increase associated with the oxidation.
The specific surface area of the low-order titanium oxide was determined by measuring the adsorption isotherm of nitrogen gas and analyzing it by the BET method. Specifically, the sample tube containing about 0.1 g of the sample was dried under reduced pressure at 200 ° C. for 12 hours, and the mass after drying was measured. Next, the sample was attached to a specific surface area meter (BELSORP-miniII, manufactured by Nippon Bell Co., Ltd.) and immersed in liquid nitrogen. After completion of cooling, the adsorption isotherm was measured using nitrogen as an adsorption gas. The obtained adsorption isotherm was converted into a BET isotherm, and the specific surface area was calculated from the slope and mass of the approximate straight line of the BET isotherm.
（実施例１）
反応器（幅１５０ｍｍ、奥行き７０ｍｍ、高さ５０ｍｍ）の底部に金属チタン（純度９９％以上）からなる板状電極（幅１５ｍｍ、長さ１００ｍｍ、厚み１ｍｍ）を固定した。板状電極の上部０．５ｍｍの位置に金属チタン（純度９９％以上）からなる中空電極（外径６ｍｍ、内径４ｍｍ、長さ１００ｍｍ）を設置した。板状電極の上部端面から少なくとも２０ｍｍ上が液面になるように反応器に８０℃の水をいれた。反応器を恒温バスに浸漬し、水温を８０℃で保持した。あらかじめ８０℃に予熱した水を反応器に２０ｍｌ／分で供給した。一方、中空電極の中空部を通じて２０ｍｌ／分（液線速１５．９ｍｍ／分）で反応器内の水を吸引し、放電場の水を置換できるようにした。
電極間に３２０Ｖの矩形電圧を印加し、放電時間２マイクロ秒、放電間隔１０２４マイクロ秒、放電電流５Ａでパルスプラズマ放電させた。パルスプラズマ放電開始後、中空電極の中空部を通じて吸引した水に黒色粒子が含まれることを確認した。パルスプラズマ放電を２時間行い、得られた黒色粒子を含む水をろ過し、黒色粒子を回収した。
水７０ｍｌを入れた１００ｍｌビーカーに回収した黒色粒子を入れ、超音波分散器を用いて分散させた後、３０分間静置し、沈殿した大きな粒子をデカンテーションで取り除いた。浮遊していた黒色粒子をろ過で回収し、６０℃にて３時間熱風乾燥し、黒色粒子１．３２ｇを得た。
得られた黒色粒子の熱重量分析を行ったところ、低次酸化チタン（組成式：ＴｉＯｘ（ｘ＝１．７６）であることが確認できた。図１に示すＸ線回折スペクトル（縦軸は強度、横軸は２θである）では、亜酸化チタンに特徴的なピークが観察された。得られた低次酸化チタンのＴＥＭ写真を図２に示す。得られた低次酸化チタンは粒子径が５〜２０ｎｍであった。図３に得られた低次酸化チタンの窒素ガスの吸着等温線を示す（縦軸は窒素の吸着量（標準状態（０℃、１atm）において吸着した量の窒素が占める体積（ｃｍ３(STP)ｇ-1））、横軸は平衡圧力を飽和蒸気圧で割った相対圧（P/P0）である）。この吸着等温線をＢＥＴ法で解析した結果、比表面積は９２ｍ２／ｇであった。
Example 1
A plate electrode (width 15 mm, length 100 mm, thickness 1 mm) made of titanium metal (purity 99% or more) was fixed to the bottom of the reactor (width 150 mm, depth 70 mm, height 50 mm). A hollow electrode (outer diameter 6 mm, inner diameter 4 mm, length 100 mm) made of titanium metal (purity 99% or more) was placed at a position 0.5 mm above the plate electrode. Water at 80 ° C. was poured into the reactor so that the liquid level was at least 20 mm above the upper end surface of the plate electrode. The reactor was immersed in a constant temperature bath, and the water temperature was kept at 80 ° C. Water preheated to 80 ° C. was fed to the reactor at 20 ml / min. On the other hand, water in the reactor was sucked through the hollow part of the hollow electrode at a rate of 20 ml / min (liquid linear velocity of 15.9 mm / min) so that the water in the discharge field could be replaced.
A rectangular voltage of 320 V was applied between the electrodes, and pulse plasma discharge was performed at a discharge time of 2 microseconds, a discharge interval of 1024 microseconds, and a discharge current of 5 A. After starting the pulse plasma discharge, it was confirmed that black particles were contained in the water sucked through the hollow portion of the hollow electrode. Pulse plasma discharge was performed for 2 hours, and the resulting water containing black particles was filtered to collect black particles.
The recovered black particles were placed in a 100 ml beaker containing 70 ml of water, dispersed using an ultrasonic disperser, and allowed to stand for 30 minutes, and the precipitated large particles were removed by decantation. The suspended black particles were collected by filtration and dried with hot air at 60 ° C. for 3 hours to obtain 1.32 g of black particles.
When the obtained black particles were subjected to thermogravimetric analysis, they were confirmed to be low-order titanium oxide (composition formula: TiOx (x = 1.76). The X-ray diffraction spectrum shown in FIG. (A strength and a horizontal axis are 2θ), a characteristic peak of titanium suboxide was observed, and a TEM photograph of the obtained low-order titanium oxide is shown in Fig. 2. The obtained low-order titanium oxide has a particle size of 3 shows a nitrogen gas adsorption isotherm of the low-order titanium oxide obtained in Fig. 3 (the vertical axis represents the amount of nitrogen adsorbed (the amount of nitrogen adsorbed in the standard state (0 ° C, 1 atm)). (Cm 3 (STP) g -1 )), and the horizontal axis is the relative pressure (P / P 0 ) obtained by dividing the equilibrium pressure by the saturated vapor pressure.) Results of analyzing this adsorption isotherm by the BET method The specific surface area was 92 m 2 / g.
（実施例２）
反応器（幅１５０ｍｍ、奥行き７０ｍｍ、高さ５０ｍｍ）の底部に金属チタン（純度９９％以上）からなる板状電極（幅１５ｍｍ、長さ１００ｍｍ、厚み１ｍｍ）を固定した。板状電極の上部０．５ｍｍの位置に金属チタン（純度９９％以上）からなる中空電極（外径６ｍｍ、内径４ｍｍ、長さ１００ｍｍ）を設置した。板状電極の上部端面から少なくとも２０ｍｍ上が液面になるように反応器に２５℃の水をいれた。反応器を恒温バスに浸漬し、水温を２５℃で保持した。あらかじめ２５℃に調整した水を、反応器に２０ｍｌ／分で供給し、一方、中空電極の中空部を通じて２０ｍｌ／分で反応器内の水を吸引し、放電場の水を置換できるようにした。
電極間に３２０Ｖの矩形のパルス電圧を印加し、放電時間１０２４マイクロ秒、放電間隔１０２４マイクロ秒、放電電流は５Ａでパルスプラズマ放電を行った。放電開始後、中空電極の中空部を通じて吸引した水に黒色粒子が含まれることを確認した。パルスプラズマ放電を２時間行い、得られた黒色粒子を含む水をろ過し、黒色粒子を回収した。水７０ｍｌを入れた１００ｍｌビーカーに回収した黒色粒子を入れ、超音波分散器を用いて分散させた後、３０分間静置し、沈殿した大きな粒子をデカンテーションで取り除いた。浮遊する黒色粒子をろ過で回収し、６０℃にて３時間熱風乾燥し、黒色粒子１．６７ｇを得た。
得られた黒色粒子の熱重量分析を行ったところ、低次酸化チタン（組成式：ＴｉＯｘ（ｘ＝１．８８）であることが確認できた。図４に示すＸ線回折スペクトル（縦軸は強度、横軸は２θである）では亜酸化チタンに特徴的なピークが観察された。図５に得られた低次酸化チタンの窒素ガスの吸着等温線を示す（縦軸、横軸は実施例１と同様である）。この吸着等温線をＢＥＴ法で解析した結果、比表面積は９９ｍ２／ｇであった。
(Example 2)
A plate electrode (width 15 mm, length 100 mm, thickness 1 mm) made of titanium metal (purity 99% or more) was fixed to the bottom of the reactor (width 150 mm, depth 70 mm, height 50 mm). A hollow electrode (outer diameter 6 mm, inner diameter 4 mm, length 100 mm) made of titanium metal (purity 99% or more) was placed at a position 0.5 mm above the plate electrode. Water at 25 ° C. was poured into the reactor so that the liquid level was at least 20 mm above the upper end surface of the plate electrode. The reactor was immersed in a constant temperature bath and the water temperature was kept at 25 ° C. Water previously adjusted to 25 ° C. was supplied to the reactor at 20 ml / min, while water in the reactor was sucked at 20 ml / min through the hollow part of the hollow electrode so that the water in the discharge field could be replaced. .
A 320 V rectangular pulse voltage was applied between the electrodes, a pulse plasma discharge was performed at a discharge time of 1024 microseconds, a discharge interval of 1024 microseconds, and a discharge current of 5A. After the start of discharge, it was confirmed that black particles were contained in the water sucked through the hollow part of the hollow electrode. Pulse plasma discharge was performed for 2 hours, and the resulting water containing black particles was filtered to collect black particles. The recovered black particles were placed in a 100 ml beaker containing 70 ml of water, dispersed using an ultrasonic disperser, and allowed to stand for 30 minutes, and the precipitated large particles were removed by decantation. The floating black particles were collected by filtration and dried with hot air at 60 ° C. for 3 hours to obtain 1.67 g of black particles.
When the obtained black particles were subjected to thermogravimetric analysis, they were confirmed to be low-order titanium oxide (compositional formula: TiOx (x = 1.88). The X-ray diffraction spectrum shown in FIG. Intensity, the horizontal axis is 2θ), a characteristic peak was observed for titanium suboxide, and the nitrogen gas adsorption isotherm of the low-order titanium oxide obtained is shown in Fig. 5 This is the same as Example 1. As a result of analyzing this adsorption isotherm by the BET method, the specific surface area was 99 m 2 / g.
（比較例１）
反応器（幅１５０ｍｍ、奥行き７０ｍｍ、高さ５０ｍｍ）の底部にチタン金属（純度９９％以上）からなる板状電極（幅１５ｍｍ、長さ１００ｍｍ、厚み１ｍｍ）を固定した。板状電極の上部にチタン金属（純度９９％以上）の棒電極（直径５ｍｍ、長さ１００ｍｍ）を設置した。板状電極の上部端面から少なくとも２０ｍｍ上が液面になるように反応器に水をいれた。反応器を恒温バスに浸漬し、水温を８０℃で保持した。電極間に３２０Ｖの矩形のパルス電圧を印加し、放電時間２マイクロ秒、放電間隔１０２４マイクロ秒、放電電流５Ａでパルスプラズマ放電させた。放電開始後、電極間に黒色粒子が生成することを確認した。パルスプラズマ放電を２時間行い、得られた黒色粒子を含む水をろ過し、黒色粒子を回収した。水７０ｍｌを入れた１００ｍｌビーカーに回収した黒色粒子を入れ、超音波分散器を用いて分散させた後、３０分間静置し、沈殿した大きな粒子をデカンテーションで取り除いた。浮遊する黒色粒子をろ過で回収し、６０℃にて３時間熱風乾燥し、黒色粒子１．０１ｇを得た。
得られた黒色粒子の熱重量分析を行ったところ、低次酸化チタン（組成式：ＴｉＯｘ（ｘ＝１．７７））であることが確認できた。図６に示すＸ線回折スペクトル（縦軸は強度、横軸は２θである）では亜酸化チタンに特徴的なピークが観察された。図７に得られた低次酸化チタンの窒素ガスの吸着等温線を示す（縦軸、横軸は実施例１と同様である）。この吸着等温線をＢＥＴ法で解析した結果、低次酸化チタンの比表面積は１６ｍ２／ｇであった。
(Comparative Example 1)
A plate electrode (width 15 mm, length 100 mm, thickness 1 mm) made of titanium metal (purity 99% or more) was fixed to the bottom of the reactor (width 150 mm, depth 70 mm, height 50 mm). A rod electrode (diameter 5 mm, length 100 mm) of titanium metal (purity 99% or more) was placed on the plate electrode. Water was poured into the reactor so that the liquid surface was at least 20 mm above the upper end surface of the plate electrode. The reactor was immersed in a constant temperature bath, and the water temperature was kept at 80 ° C. A 320 V rectangular pulse voltage was applied between the electrodes, and a pulse plasma discharge was performed with a discharge time of 2 microseconds, a discharge interval of 1024 microseconds, and a discharge current of 5 A. After starting the discharge, it was confirmed that black particles were generated between the electrodes. Pulse plasma discharge was performed for 2 hours, and the resulting water containing black particles was filtered to collect black particles. The recovered black particles were placed in a 100 ml beaker containing 70 ml of water, dispersed using an ultrasonic disperser, and allowed to stand for 30 minutes, and the precipitated large particles were removed by decantation. The floating black particles were collected by filtration and dried with hot air at 60 ° C. for 3 hours to obtain 1.01 g of black particles.
As a result of thermogravimetric analysis of the obtained black particles, it was confirmed that it was low-order titanium oxide (composition formula: TiO x (x = 1.77)). In the X-ray diffraction spectrum shown in FIG. 6 (vertical axis is intensity, horizontal axis is 2θ), a peak characteristic of titanium suboxide was observed. FIG. 7 shows the adsorption isotherm of nitrogen gas of the low-order titanium oxide obtained (the vertical axis and the horizontal axis are the same as in Example 1). As a result of analyzing this adsorption isotherm by the BET method, the specific surface area of the low-order titanium oxide was 16 m 2 / g.
本発明によれば、光触媒用途、酸素吸収剤用途などに有用な低次酸化チタンを、工業的規模で安定的に製造し得る。 ADVANTAGE OF THE INVENTION According to this invention, the low-order titanium oxide useful for a photocatalyst use, an oxygen absorber use, etc. can be manufactured stably on an industrial scale.
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