JP2011110494A - Si-Fe BASED COMPOSITE OXIDE AND METHOD FOR MANUFACTURING THE SAME - Google Patents
Si-Fe BASED COMPOSITE OXIDE AND METHOD FOR MANUFACTURING THE SAME Download PDFInfo
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- 239000002131 composite material Substances 0.000 title claims abstract description 48
- 229910018619 Si-Fe Inorganic materials 0.000 title claims abstract description 31
- 229910008289 Si—Fe Inorganic materials 0.000 title claims abstract description 31
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000002002 slurry Substances 0.000 claims abstract description 22
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 20
- 230000003197 catalytic effect Effects 0.000 claims abstract description 16
- 238000001914 filtration Methods 0.000 claims abstract description 16
- 238000005406 washing Methods 0.000 claims abstract description 16
- 238000010335 hydrothermal treatment Methods 0.000 claims abstract description 15
- 238000001035 drying Methods 0.000 claims abstract description 14
- 239000011164 primary particle Substances 0.000 claims abstract description 13
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 10
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 10
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 10
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 9
- 230000008569 process Effects 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052742 iron Inorganic materials 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 4
- 230000003647 oxidation Effects 0.000 claims abstract description 3
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 3
- 239000002245 particle Substances 0.000 claims description 23
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 11
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 claims description 7
- 239000003054 catalyst Substances 0.000 abstract description 14
- 238000010304 firing Methods 0.000 abstract description 10
- 229910044991 metal oxide Inorganic materials 0.000 abstract description 7
- 150000004706 metal oxides Chemical class 0.000 abstract description 7
- 230000015572 biosynthetic process Effects 0.000 abstract 2
- 238000011109 contamination Methods 0.000 abstract 1
- LITYQKYYGUGQLY-UHFFFAOYSA-N iron nitric acid Chemical compound [Fe].O[N+]([O-])=O LITYQKYYGUGQLY-UHFFFAOYSA-N 0.000 abstract 1
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 24
- 239000007858 starting material Substances 0.000 description 11
- 239000012855 volatile organic compound Substances 0.000 description 10
- 238000000354 decomposition reaction Methods 0.000 description 9
- 239000011575 calcium Substances 0.000 description 5
- 239000013078 crystal Substances 0.000 description 5
- 238000001878 scanning electron micrograph Methods 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 238000007084 catalytic combustion reaction Methods 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000003917 TEM image Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002736 metal compounds Chemical class 0.000 description 2
- 229910000510 noble metal Inorganic materials 0.000 description 2
- 239000010412 oxide-supported catalyst Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 239000005749 Copper compound Substances 0.000 description 1
- 229910002554 Fe(NO3)3·9H2O Inorganic materials 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000003463 adsorbent Substances 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001880 copper compounds Chemical class 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011238 particulate composite Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 210000002268 wool Anatomy 0.000 description 1
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- Exhaust Gas Treatment By Means Of Catalyst (AREA)
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Abstract
Description
本発明は、ＳｉとＦｅとを含む複合酸化物であって、かつ、粒子状である新規なＳｉ−Ｆｅ系複合酸化物およびその製造方法に関する。 The present invention relates to a novel Si—Fe based composite oxide which is a composite oxide containing Si and Fe and is in the form of particles, and a method for producing the same.
近年、環境汚染などに関する問題意識の向上の観点から、工場などから排出される揮発性有機化合物（ＶＯＣ：Volatile Organic Compound）を除去するための手段が種々開発されている。一般的なＶＯＣ除去方法としては、ＶＯＣを燃焼して分解する方法の他、活性炭、シリカゲルなどの吸着剤などを用いて排出ガス中のＶＯＣを吸着除去する方法などが知られている。中でも、比較的低温でＶＯＣを酸化分解できるため、触媒活性を有する物質を用いてＶＯＣを燃焼する触媒燃焼法が注目されている。 In recent years, various means for removing volatile organic compounds (VOC) discharged from factories and the like have been developed from the viewpoint of improving awareness of problems related to environmental pollution. As a general VOC removal method, there are known a method in which VOC in an exhaust gas is adsorbed and removed using an adsorbent such as activated carbon and silica gel, in addition to a method in which VOC is burned and decomposed. Among them, since a VOC can be oxidatively decomposed at a relatively low temperature, a catalytic combustion method in which VOC is burned using a substance having catalytic activity has attracted attention.
しかしながら従来、触媒燃焼法に用い得る触媒としては、白金などの高価な貴金属を用いる必要があり、このような高価な貴金属に代わる、安価でかつ実用的な触媒材料の開発が求められている。たとえば特開２００３−１２６６９６号公報（特許文献１）には、カルシウム塩、非晶質シリカおよび銅化合物を含むＶＯＣ分解用燃焼触媒が開示されている。またたとえば特開２００５−２３８１９２号公報（特許文献２）には、担体に触媒となる金属化合物が担持された金属酸化物担持触媒であって、ＢＥＴ比表面積が５０〜５００ｍ2／ｇ、且つＪＩＳ Ｋ６２６０に準拠した吸油量が５０〜５５０ｍｌ／１００ｇの多孔質珪酸カルシウムからなる担体に、金属化合物を担持させた金属酸化物担持触媒が開示されている。 However, conventionally, it is necessary to use an expensive noble metal such as platinum as a catalyst that can be used in the catalytic combustion method, and the development of an inexpensive and practical catalyst material to replace such an expensive noble metal is required. For example, Japanese Laid-Open Patent Publication No. 2003-126696 (Patent Document 1) discloses a combustion catalyst for VOC decomposition containing a calcium salt, amorphous silica and a copper compound. Further, for example, Japanese Patent Application Laid-Open No. 2005-238192 (Patent Document 2) discloses a metal oxide-supported catalyst in which a metal compound serving as a catalyst is supported on a carrier, having a BET specific surface area of 50 to 500 m 2 / g and JIS. A metal oxide-supported catalyst in which a metal compound is supported on a support made of porous calcium silicate having an oil absorption amount of 50 to 550 ml / 100 g according to K6260 is disclosed.
触媒燃焼法においては、より低い温度で効率よくＶＯＣを燃焼する観点からは、金属酸化物触媒の触媒活性は高ければ高いほどよく、従来よりも触媒活性が改善された新規な金属酸化物触媒の開発が求められている。 In the catalytic combustion method, from the viewpoint of efficiently burning VOC at a lower temperature, the higher the catalytic activity of the metal oxide catalyst, the better, and a novel metal oxide catalyst with improved catalytic activity compared to the conventional ones. Development is required.
本発明は、上記課題を解決するためになされたものであって、その目的とするところは、従来よりも触媒活性が改善された新規な金属酸化物触媒およびその製造方法を提供することである。 The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a novel metal oxide catalyst having improved catalytic activity as compared with the prior art and a method for producing the same. .
本発明は、ＳｉとＦｅとを含む複合酸化物であって、Ｆｅを含む一次粒子の粒径が１００ｎｍ以下、かつ、アスペクト比が２．０以下である、酸化触媒作用を有するＳｉ−Ｆｅ系複合酸化物に関する。 The present invention is a composite oxide containing Si and Fe, wherein the primary particles containing Fe have a particle size of 100 nm or less and an aspect ratio of 2.0 or less, and have an oxidation catalytic action. The present invention relates to a composite oxide.
本発明のＳｉ−Ｆｅ系複合酸化物において、Ｆｅの含有組成は酸化鉄として３０〜５０重量％であることが、好ましい。 In the Si—Fe-based composite oxide of the present invention, the Fe-containing composition is preferably 30 to 50% by weight as iron oxide.
本発明のＳｉ−Ｆｅ系複合酸化物において、ＢＥＴ比表面積が１００ｍ2／ｇ以上であることが好ましい。 In the Si—Fe based complex oxide of the present invention, the BET specific surface area is preferably 100 m 2 / g or more.
本発明はまた、水酸化カルシウムとシリカと硝酸鉄とを配合し、純水を加えて混濁させスラリーを生成するスラリー生成工程と、生成したスラリーを水熱処理する水熱処理工程と、水熱処理後の複合物をろ過・洗浄するろ過・洗浄工程と、ろ過・洗浄後の複合物を乾燥させる乾燥工程と、乾燥後の複合物を焼成する焼成工程とを含むＳｉ−Ｆｅ系複合酸化物の製造方法についても提供する。 The present invention also includes a slurry generation step in which calcium hydroxide, silica, and iron nitrate are blended and turbidized by adding pure water to generate a slurry; a hydrothermal treatment step in which the generated slurry is hydrothermally treated; Filtration / washing step for filtering / washing composite, drying step for drying composite after filtration / washing, and method for producing Si-Fe-based composite oxide comprising firing step for firing composite after drying Also provide about.
本発明によれば、従来よりも触媒活性が改善された新規な金属酸化物触媒およびその製造方法が提供される。 ADVANTAGE OF THE INVENTION According to this invention, the novel metal oxide catalyst by which the catalyst activity was improved compared with the past, and its manufacturing method are provided.
本発明のＳｉ−Ｆｅ系複合酸化物は、ＳｉとＦｅとを含む複合酸化物であって、Ｆｅを含む一次粒子の粒径が１００ｎｍ以下、かつ、アスペクト比が２．０以下であることを特徴とする。このように特定の一次粒子の粒径およびアスペクト比を兼ね備えた、いわば「粒子状」の本発明のＳｉ−Ｆｅ系複合酸化物によれば、実験例にて詳細に上述するように優れた触媒活性が発揮される。水酸化カルシウムとシリカを出発物質とする複合体の場合、通常、板状または針状の（すなわち、アスペクト比が２．０を超える）結晶構造体となる。今回、本発明者らにより初めて、水酸化カルシウムとシリカに加え、出発物質として硝酸鉄をさらに用いる新規な製造方法が開発され、粒子状の（すなわち、アスペクト比が２．０以下の）複合体が得られた。 The Si—Fe-based composite oxide of the present invention is a composite oxide containing Si and Fe, wherein the primary particles containing Fe have a particle size of 100 nm or less and an aspect ratio of 2.0 or less. Features. Thus, according to the so-called “particulate” Si—Fe-based composite oxide of the present invention having both the particle size and the aspect ratio of specific primary particles, an excellent catalyst as described in detail in the experimental examples. Activity is demonstrated. In the case of a complex using calcium hydroxide and silica as starting materials, it usually has a plate-like or needle-like (that is, the aspect ratio exceeds 2.0) crystal structure. This time, for the first time, the inventors have developed a novel production method that further uses iron nitrate as a starting material in addition to calcium hydroxide and silica, and a particulate composite (that is, an aspect ratio of 2.0 or less). was gotten.
本発明のＳｉ−Ｆｅ系複合酸化物において、Ｆｅを含む一次粒子の粒径が１００ｎｍ以下である。Ｆｅを含む一次粒子の粒径が１００ｎｍを超えてしまうと、触媒活性が極端に減少してしまう。このような触媒活性の極端な減少を防ぐ観点から、本発明のＳｉ−Ｆｅ系複合酸化物におけるＦｅを含む一次粒子の粒径は７０ｎｍ以下であることが好ましい。また、本発明のＳｉ−Ｆｅ系複合酸化物は、粒径がより小さくなるほど触媒活性は向上する傾向にあるため、Ｆｅを含む一次粒子の粒径の下限値は特に制限されるものではないが、２ｎｍ以上であることが好ましく、５ｎｍ以上であることがより好ましい。なお、このＦｅを含む一次粒子の粒径は、ＴＥＭ画像を用いた解析手法により測定された値を指す。 In the Si—Fe composite oxide of the present invention, the primary particles containing Fe have a particle size of 100 nm or less. If the particle size of the primary particles containing Fe exceeds 100 nm, the catalytic activity is extremely reduced. From the viewpoint of preventing such an extreme decrease in catalytic activity, the primary particles containing Fe in the Si—Fe based composite oxide of the present invention preferably have a particle size of 70 nm or less. In addition, since the Si—Fe based composite oxide of the present invention tends to improve the catalytic activity as the particle size becomes smaller, the lower limit value of the particle size of the primary particles containing Fe is not particularly limited. The thickness is preferably 2 nm or more, and more preferably 5 nm or more. The particle size of the primary particles containing Fe indicates a value measured by an analysis method using a TEM image.
また本発明のＳｉ−Ｆｅ系複合酸化物において、アスペクト比は２．０以下である。アスペクト比が２．０を超えてしまうと、触媒活性が極端に減少してしまう。このような触媒活性の極端な減少を防ぐ観点から、本発明のＳｉ−Ｆｅ系複合酸化物におけるアスペクト比は１．５以下であることが好ましい。また、本発明のＳｉ−Ｆｅ系複合酸化物におけるアスペクト比の下限値は特に制限されるものではないが、０．２以上であることが好ましく、０．５以上であることがより好ましい。なお、このアスペクト比は、ＴＥＭ画像を用いた解析手法により測定された値を指す。 In the Si—Fe composite oxide of the present invention, the aspect ratio is 2.0 or less. When the aspect ratio exceeds 2.0, the catalytic activity is extremely reduced. From the viewpoint of preventing such an extreme decrease in catalytic activity, the aspect ratio of the Si—Fe based composite oxide of the present invention is preferably 1.5 or less. Further, the lower limit of the aspect ratio in the Si—Fe based composite oxide of the present invention is not particularly limited, but is preferably 0.2 or more, and more preferably 0.5 or more. In addition, this aspect ratio points out the value measured by the analysis method using a TEM image.
本発明のＳｉ−Ｆｅ系複合酸化物において、Ｆｅの含有組成は酸化鉄として３０〜５０重量％であることが好ましく、３０〜３５重量％であることがより好ましい。Ｆｅの含有組成が酸化鉄として３０重量％未満である場合には、球状のＦｅ粒子がうまく発現しない傾向にあるためであり、また、Ｆｅの含有組成が酸化鉄として５０重量％を超える場合には、球状のＦｅ粒子の粒径が肥大化してしまう傾向にあるためである。なお、Ｓｉ−Ｆｅ系複合酸化物における酸化鉄の含有組成は、たとえば蛍光Ｘ線を用いた無機元素分析を用いて測定することができる。 In the Si—Fe-based composite oxide of the present invention, the Fe-containing composition is preferably 30 to 50% by weight as iron oxide, and more preferably 30 to 35% by weight. This is because when the Fe-containing composition is less than 30% by weight as iron oxide, spherical Fe particles tend not to develop well, and when the Fe-containing composition exceeds 50% by weight as iron oxide. This is because the particle size of the spherical Fe particles tends to be enlarged. In addition, the content composition of the iron oxide in Si-Fe type complex oxide can be measured, for example using the inorganic element analysis which used the fluorescent X ray.
また本発明のＳｉ−Ｆｅ系複合酸化物において、ＢＥＴ比表面積が１００ｍ2／ｇ以上であることが好ましく、１２０ｍ2／ｇ以上であることがより好ましい。ＢＥＴ比表面積が１００ｍ2／ｇ未満である場合には、触媒活性が減少してしまう傾向にあるためである。なお、一般的に金属酸化物触媒におけるＢＥＴ比表面積は大きければ大きいほどよいので、その上限値は特に制限されるものではない。なお、Ｓｉ−Ｆｅ系複合酸化物におけるＢＥＴ比表面積は、たとえば自動比表面積測定装置ジェミニ２３７５（マイクロメリティックス社製）を用いて測定することができる。 In the Si—Fe based composite oxide of the present invention, the BET specific surface area is preferably 100 m 2 / g or more, and more preferably 120 m 2 / g or more. This is because the catalytic activity tends to decrease when the BET specific surface area is less than 100 m 2 / g. In general, the larger the BET specific surface area of a metal oxide catalyst, the better. Therefore, the upper limit is not particularly limited. In addition, the BET specific surface area in Si-Fe type complex oxide can be measured using the automatic specific surface area measuring device Gemini 2375 (made by Micromeritics), for example.
本発明はまた、上述した本発明のＳｉ−Ｆｅ系複合酸化物の新規な製造方法も提供する。本発明のＳｉ−Ｆｅ系複合酸化物の製造方法は、水酸化カルシウムとシリカと硝酸鉄とを配合し、純水を加えて混濁させスラリーを生成するスラリー生成工程と、生成したスラリーを水熱処理する水熱処理工程と、水熱処理後の複合物をろ過・洗浄するろ過・洗浄工程と、ろ過・洗浄後の複合物を乾燥させる乾燥工程と、乾燥後の複合物を焼成する焼成工程とを含むことを特徴とする。なお、本発明のＳｉ−Ｆｅ系複合酸化物は、上述した特徴を有するものであればその製造方法は特に制限されるものではないが、本発明の方法によって製造されたものであることが好ましい。以下、本発明のＳｉ−Ｆｅ系複合酸化物の製造方法の各工程について詳細に説明する。 The present invention also provides a novel method for producing the above-described Si—Fe based composite oxide of the present invention. The method for producing a Si—Fe-based composite oxide of the present invention includes a slurry generation step of mixing calcium hydroxide, silica, and iron nitrate, adding pure water to turbidity to generate a slurry, and hydrothermally treating the generated slurry. A hydrothermal treatment step, a filtration / washing step for filtering / washing the composite after hydrothermal treatment, a drying step for drying the composite after filtration / washing, and a firing step for firing the dried composite It is characterized by that. In addition, although the manufacturing method in particular is not restrict | limited if the Si-Fe type complex oxide of this invention has the characteristic mentioned above, It is preferable that it was manufactured by the method of this invention. . Hereafter, each process of the manufacturing method of the Si-Fe type complex oxide of this invention is demonstrated in detail.
〔１〕スラリー生成工程
スラリー生成工程ではまず、水酸化カルシウムとシリカと硝酸鉄とを配合し、純水を加えて混濁させスラリーを生成する。ここで、本発明においては、Ｆｅ粒子の粒径の肥大化を抑制するという理由から、出発物質として水酸化カルシウムを用いる。またＦｅ粒子を固定化させるという理由から、Ｓｉ源の出発物質としてシリカを用いる。さらに、溶液中に固溶化させる目的から、Ｆｅ源の出発物質として硝酸鉄を用いる。この際、上述したより好ましい本発明のＳｉ−Ｆｅ系複合酸化物を製造する観点からは、Ｆｅの含有組成が酸化鉄として３０〜５０重量％の範囲となるような比率で出発物質を配合することが好ましい。
[1] Slurry generation step In the slurry generation step, first, calcium hydroxide, silica, and iron nitrate are blended, and pure water is added to cause turbidity to generate a slurry. Here, in the present invention, calcium hydroxide is used as a starting material because it suppresses the enlargement of the particle size of Fe particles. Also, silica is used as a starting material for the Si source because Fe particles are immobilized. Further, iron nitrate is used as a starting material for the Fe source for the purpose of forming a solid solution in the solution. Under the present circumstances, from a viewpoint of manufacturing the more preferable Si-Fe type complex oxide of this invention mentioned above, a starting material is mix | blended in the ratio which the content composition of Fe becomes in the range of 30 to 50 weight% as iron oxide. It is preferable.
ここで、従来、水酸化カルシウムとシリカを出発物質とする複合体は、Ｓｉの集合体が凝集した際に発現しうる形態の、板状または針状の結晶構造体となっていた。本発明の製造方法では、出発物質として硝酸鉄を配合していることで、その詳細な理由は不明であるが、上述したような特定のＦｅを含む一次粒子の粒子径およびアスペクト比を有する複合体が得られる。なお、得られるＳｉ−Ｆｅ系複合酸化物のＦｅを含む一次粒子の粒子径およびアスペクト比は、その製造方法において出発物質である水酸化カルシウムの配合量を調整することで制御できる。 Heretofore, a complex using calcium hydroxide and silica as a starting material has conventionally been a plate-like or needle-like crystal structure that can be expressed when an aggregate of Si aggregates. In the production method of the present invention, since iron nitrate is blended as a starting material, the detailed reason is unknown, but the composite having the particle diameter and aspect ratio of the primary particles containing specific Fe as described above. The body is obtained. In addition, the particle diameter and aspect ratio of the primary particle containing Fe of the obtained Si—Fe composite oxide can be controlled by adjusting the blending amount of calcium hydroxide as a starting material in the production method.
本発明の製造方法において、当該工程で生成するスラリーは、ｐＨを２〜７の範囲内とすることが好ましい。スラリーのｐＨが２未満である場合には、水熱処理中に溶解してしまい、ろ過工程を経ても固形分を得ることはできない傾向にあり、また、スラリーのｐＨは７を超える場合には、比表面積が低下し、結晶子径が肥大化することで触媒活性が減少する傾向にあるためである。よって、高比表面積、且つ、結晶子径の小さいＳｉ−Ｆｅ系複合酸化物を得るために、スラリーのｐＨは２．０〜７．０の範囲内であることが好ましい。スラリーのｐＨは、たとえば出発物質に水酸化ナトリウムを滴下するというようにして調整することができる。 In the production method of the present invention, the slurry produced in this step preferably has a pH in the range of 2-7. When the pH of the slurry is less than 2, it is dissolved during the hydrothermal treatment, and there is a tendency that a solid content cannot be obtained even after passing through the filtration step. When the pH of the slurry exceeds 7, This is because the specific surface area is reduced and the crystallite diameter is enlarged so that the catalytic activity tends to decrease. Therefore, in order to obtain a Si—Fe based composite oxide having a high specific surface area and a small crystallite diameter, the pH of the slurry is preferably in the range of 2.0 to 7.0. The pH of the slurry can be adjusted, for example, by adding sodium hydroxide dropwise to the starting material.
〔２〕水熱処理工程
続く工程では、生成されたスラリーを水熱処理する。ここで、当該技術を使わず固相反応を行った場合には、固相内のイオン拡散により反応する。これに対し、水熱処理を行う場合には、イオンの溶解−析出機構によって反応が進行するため、水熱処理は通常の固相処理と比較して反応速度が速く、生成物組成の均一性が高く、形状制御が可能となる。このような理由により、本発明では水熱処理を採用する。水熱処理は、具体的には、オートクレーブを用いて行うことができ、その条件としては、圧力（飽和蒸気圧）が２００ｋＰａ以上、処理温度が１２０〜１９０℃の範囲内、処理時間が１〜２時間の範囲内とすることが好適である。
[2] Hydrothermal treatment step In the subsequent step, the produced slurry is hydrothermally treated. Here, when a solid-phase reaction is performed without using the technique, the reaction occurs by ion diffusion in the solid phase. On the other hand, in the case of hydrothermal treatment, the reaction proceeds by the ion dissolution-precipitation mechanism. Therefore, the hydrothermal treatment has a higher reaction rate than that of a normal solid phase treatment, and the uniformity of the product composition is high. , Shape control becomes possible. For these reasons, hydrothermal treatment is employed in the present invention. Specifically, the hydrothermal treatment can be performed using an autoclave. The conditions include a pressure (saturated vapor pressure) of 200 kPa or higher, a processing temperature in the range of 120 to 190 ° C., and a processing time of 1 to 2. It is preferable to be within the time range.
〔３〕ろ過・洗浄工程
続く工程では、水熱処理後の複合物をろ過・洗浄する。ろ過および洗浄の操作は、当分野における通常の手段を適宜用いて行うことができ、特に制限されるものではない。
[3] Filtration / washing step In the subsequent step, the composite after hydrothermal treatment is filtered and washed. Filtration and washing operations can be carried out by appropriately using ordinary means in this field, and are not particularly limited.
〔４〕乾燥工程
続く工程では、ろ過・洗浄後の複合物を乾燥させる。乾燥の操作は、当分野における通常の手段を適宜用いて行うことができ、特に制限されるものではない。乾燥の条件も特に制限されないが、８０〜１２０℃の範囲内の温度で、１０〜１５時間乾燥させる条件が好適である。
[4] Drying step In the subsequent step, the composite after filtration and washing is dried. The drying operation can be performed by appropriately using ordinary means in this field, and is not particularly limited. The drying conditions are not particularly limited, but conditions for drying at a temperature in the range of 80 to 120 ° C. for 10 to 15 hours are preferable.
〔５〕焼成工程
続く工程では、乾燥後の複合物を焼成する。焼成の操作も、当分野における通常の手段を適宜用いて行うことができ、特に制限されるものではない。焼成の条件も特に制限されないが、５５０〜６５０℃の範囲内の温度で、５時間空気雰囲気下で焼成させる条件が好適である。
[5] Firing step In the subsequent step, the dried composite is fired. The firing operation can also be carried out by appropriately using ordinary means in this field, and is not particularly limited. There are no particular restrictions on the firing conditions, but the preferred conditions are firing at a temperature in the range of 550 to 650 ° C. for 5 hours in an air atmosphere.
このような本発明の製造方法により、上述した本発明のＳｉ−Ｆｅ系複合酸化物を好適に製造できる。本発明のＳｉ−Ｆｅ系複合酸化物は、たとえばボールミルなど公知の手段を用いて粉砕し、適当な粒径範囲（好ましくは３００〜５００μｍ）のものを分級することで、ＶＯＣの触媒燃焼法に好適に用いられ得る金属酸化物触媒として供することができる。 By such a production method of the present invention, the above-described Si—Fe based composite oxide of the present invention can be suitably produced. The Si—Fe-based composite oxide of the present invention is pulverized using a known means such as a ball mill and classified into an appropriate particle size range (preferably 300 to 500 μm), so that it can be used in a VOC catalytic combustion method. It can serve as a metal oxide catalyst that can be suitably used.
以下、実験例を挙げて本発明をより詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, although an example of an experiment is given and the present invention is explained in detail, the present invention is not limited to these.
＜実験例１＞
最終生成物に含まれるＦｅ2Ｏ3重量組成がそれぞれ０重量％（サンプル１）、１０重量％（サンプル２）、３０重量％（サンプル３）、５０重量％（サンプル４）、７０重量％（サンプル５）となるように、秤量したＦｅ（ＮＯ3）3・９Ｈ2ＯとＣａ（ＯＨ）2とＳｉＯ2とをＣａ／Ｓｉのモル比が０．６となるように調整し、蒸留水を加え均一に攪拌し、スラリー（ｐＨ２．０）を生成させた。その後、オートクレーブにて飽和蒸気圧１９９ｋＰａ、１２０℃、１２時間の条件下で水熱処理を行った後、ろ過および洗浄した。これを１００℃、６時間の条件下で乾燥させた後、６００℃、５時間空気雰囲気下で焼成を行った。このようにしてＦｅ含有量を変動させたＳｉ−Ｆｅ系複合酸化物のサンプル１〜５を作製した。
<Experimental example 1>
The final composition of Fe 2 O 3 contained in the final product is 0% by weight (sample 1), 10% by weight (sample 2), 30% by weight (sample 3), 50% by weight (sample 4), 70% by weight ( Weighed Fe (NO 3 ) 3 · 9H 2 O, Ca (OH) 2, and SiO 2 so as to be sample 5) were adjusted so that the molar ratio of Ca / Si was 0.6, and distilled water Was added and stirred uniformly to produce a slurry (pH 2.0). Thereafter, hydrothermal treatment was performed in an autoclave under the conditions of saturated vapor pressure of 199 kPa, 120 ° C., and 12 hours, followed by filtration and washing. This was dried at 100 ° C. for 6 hours, and then fired at 600 ° C. for 5 hours in an air atmosphere. In this way, samples 1 to 5 of the Si—Fe based composite oxide with varying Fe content were prepared.
このようにして得られたサンプル１〜５をそれぞれボールミルで粉砕し、粒径３００〜５００μｍに分級した後、Ｓｉ−Ｆｅ系複合酸化物を、直径４ｍｍのＵ字管に充填し、上下をアルミナウールで固定した。その後、気化させたトルエン５０００ｐｐｍ、ＳＶ４００００／時間の相当流量に調整しつつＵ字管に送り、各２００〜７００℃で酸化分解反応させ、その分解物をＧＣ（島津製作所製）にかけ、トルエンの濃度（％）を測定し、トルエンの５０％が分解されたときの温度（Ｔ５０）を算出した。またサンプル１〜５について、ＴＥＭ画像を用いた解析手法によりＦｅを含む一次粒子の粒子径およびアスペクト比、窒素ガス吸着法を用いてＢＥＴ比表面積をそれぞれ測定した。結果を表１に示す。 The samples 1 to 5 thus obtained were each pulverized with a ball mill and classified to a particle size of 300 to 500 μm, and then a Si-Fe composite oxide was filled in a U-shaped tube having a diameter of 4 mm, and the upper and lower sides were alumina. Fixed with wool. Thereafter, the vaporized toluene is adjusted to an equivalent flow rate of 5000 ppm and SV40000 / hour, and sent to a U-shaped tube. (%) Was measured, and the temperature (T50) when 50% of toluene was decomposed was calculated. For Samples 1 to 5, the particle diameter and aspect ratio of primary particles containing Fe were measured by an analysis method using a TEM image, and the BET specific surface area was measured using a nitrogen gas adsorption method. The results are shown in Table 1.
ここで、図１は、実験例１で得られた各サンプルについての温度とトルエンの分解率との関係を示すグラフであり、縦軸は分解率（％）、横軸は温度（℃）である。また図２（ａ）はサンプル１、図２（ｂ）はサンプル２、図２（ｃ）はサンプル３、図２（ｄ）はサンプル４、図２（ｅ）はサンプル５についてのＳＥＭ画像写真である。Ｆｅ含有量３０〜５０重量％であるサンプル３、４は、Ｆｅ含有量が０％であるサンプル１と比較すると、ＢＥＴ比表面積が大きく増大し、トルエン分解温度が大きく低下する、すなわち、触媒活性が向上する結果となっていることが分かる。また、Ｆｅ含有量が０％であるサンプル１は、ＳＥＭ画像では板状の結晶状態となる（図２（ａ））が、Ｆｅを含むサンプル２〜５では、粒子状の結晶状態となり比表面積も大きく増大することが分かる（図２（ｂ）、（ｃ）、（ｄ）、（ｅ））。 Here, FIG. 1 is a graph showing the relationship between the temperature and the decomposition rate of toluene for each sample obtained in Experimental Example 1, the vertical axis is the decomposition rate (%), and the horizontal axis is the temperature (° C.). is there. 2A is a sample 1, FIG. 2B is a sample 2, FIG. 2C is a sample 3, FIG. 2D is a sample 4, FIG. 2E is a SEM image of the sample 5. It is. Samples 3 and 4 having an Fe content of 30 to 50% by weight greatly increase the BET specific surface area and greatly reduce the toluene decomposition temperature compared to Sample 1 having an Fe content of 0%, that is, catalytic activity. It can be seen that the result is improved. Sample 1 having an Fe content of 0% is in a plate-like crystal state in the SEM image (FIG. 2A), but samples 2 to 5 containing Fe are in a particle-like crystal state and have a specific surface area. (Fig. 2 (b), (c), (d), (e)).
＜実験例２＞
最終生成物に含まれるＦｅ2Ｏ3重量組成が３０重量％であり、仕込み時におけるＣａ／Ｓｉのモル比がそれぞれ０．３（サンプル６）、０．６（サンプル７）、０．９（サンプル８）、１．３（サンプル９）、２．０（サンプル１０）となるように出発物質を配合したこと以外は実験例１と同様にしてＳｉ−Ｆｅ系複合酸化物のサンプル６〜１０を作製した。実験例１と同様にして、トルエンの分解率（％）、Ｔ５０、粒子径、アスペクト比、ＢＥＴ比表面積を測定した。結果を表２に示す。
<Experimental example 2>
The Fe 2 O 3 weight composition contained in the final product is 30% by weight, and the molar ratio of Ca / Si at the time of charging is 0.3 (sample 6), 0.6 (sample 7), 0.9 ( Samples 6 to 10 of Si—Fe-based composite oxides in the same manner as in Experimental Example 1 except that the starting materials were blended so as to be Samples 8), 1.3 (Sample 9), and 2.0 (Sample 10). Was made. In the same manner as in Experimental Example 1, the decomposition rate (%) of toluene, T50, particle diameter, aspect ratio, and BET specific surface area were measured. The results are shown in Table 2.
ここで、図３は、実験例２で得られた各サンプルについての温度とトルエンの分解率との関係を示すグラフであり、縦軸は分解率（％）、横軸は温度（℃）である。また図４（ａ）はサンプル６、図４（ｂ）はサンプル７、図４（ｃ）はサンプル８、図４（ｄ）はサンプル９、図４（ｅ）はサンプル１０についてのＳＥＭ画像写真である。Ｃａ／Ｓｉのモル比が０．３〜０．９の範囲であるサンプル６〜８では、細かい粒子状の結晶状態を発現していることが確認されるが、Ｃａ／Ｓｉ比を１．３以上としたサンプル９、１０では、粒が大きくなり触媒活性の低下に繋がることが分かる。 Here, FIG. 3 is a graph showing the relationship between the temperature and the decomposition rate of toluene for each sample obtained in Experimental Example 2, the vertical axis is the decomposition rate (%), and the horizontal axis is the temperature (° C.). is there. 4A is a sample 6, FIG. 4B is a sample 7, FIG. 4C is a sample 8, FIG. 4D is a sample 9, and FIG. 4E is a SEM image of the sample 10. It is. In Samples 6 to 8 in which the molar ratio of Ca / Si is in the range of 0.3 to 0.9, it is confirmed that a fine particulate crystal state is expressed, but the Ca / Si ratio is 1.3. In Samples 9 and 10 as described above, it can be seen that the grains become large, leading to a decrease in catalytic activity.
今回開示された実施の形態および実験例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiments and experimental examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
Claims (4)
生成したスラリーを水熱処理する水熱処理工程と、
水熱処理後の複合物をろ過・洗浄するろ過・洗浄工程と、
ろ過・洗浄後の複合物を乾燥させる乾燥工程と、
乾燥後の複合物を焼成する焼成工程とを含む、Ｓｉ−Ｆｅ系複合酸化物の製造方法。 A slurry generation step of blending calcium hydroxide, silica and iron nitrate, adding pure water to turbidity to generate a slurry,
A hydrothermal treatment step of hydrothermally treating the produced slurry;
Filtration and washing process for filtering and washing the composite after hydrothermal treatment,
A drying process for drying the composite after filtration and washing;
The manufacturing method of Si-Fe type complex oxide including the baking process which bakes the composite after drying.
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