JPH0753219A - Niobic acid particle and its production - Google Patents
Niobic acid particle and its productionInfo
- Publication number
- JPH0753219A JPH0753219A JP5225230A JP22523093A JPH0753219A JP H0753219 A JPH0753219 A JP H0753219A JP 5225230 A JP5225230 A JP 5225230A JP 22523093 A JP22523093 A JP 22523093A JP H0753219 A JPH0753219 A JP H0753219A
- Authority
- JP
- Japan
- Prior art keywords
- aqueous solution
- niobate particles
- acid
- particles
- mixed solution
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000002245 particle Substances 0.000 title claims abstract description 158
- 239000002253 acid Substances 0.000 title claims abstract description 64
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 230000002378 acidificating effect Effects 0.000 claims abstract description 51
- 238000012360 testing method Methods 0.000 claims abstract description 16
- 239000007864 aqueous solution Substances 0.000 claims description 97
- 239000011259 mixed solution Substances 0.000 claims description 55
- 150000002822 niobium compounds Chemical class 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 21
- 238000002156 mixing Methods 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 23
- 239000011973 solid acid Substances 0.000 abstract description 22
- 239000003054 catalyst Substances 0.000 abstract description 15
- 239000000203 mixture Substances 0.000 abstract description 10
- 239000010955 niobium Substances 0.000 abstract description 6
- 229910052758 niobium Inorganic materials 0.000 abstract description 6
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 abstract description 6
- 230000009467 reduction Effects 0.000 abstract description 5
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 18
- XNHGKSMNCCTMFO-UHFFFAOYSA-D niobium(5+);oxalate Chemical compound [Nb+5].[Nb+5].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O XNHGKSMNCCTMFO-UHFFFAOYSA-D 0.000 description 17
- 239000007788 liquid Substances 0.000 description 14
- 239000000243 solution Substances 0.000 description 14
- 239000000047 product Substances 0.000 description 11
- 239000002994 raw material Substances 0.000 description 11
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 8
- 238000005341 cation exchange Methods 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- -1 halogen ions Chemical class 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 238000007796 conventional method Methods 0.000 description 5
- 238000001914 filtration Methods 0.000 description 5
- 238000010304 firing Methods 0.000 description 5
- 229910052736 halogen Inorganic materials 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 4
- 238000006555 catalytic reaction Methods 0.000 description 4
- 150000001768 cations Chemical class 0.000 description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 description 4
- 239000011707 mineral Substances 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000012670 alkaline solution Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 150000002367 halogens Chemical class 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 235000006408 oxalic acid Nutrition 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 238000003916 acid precipitation Methods 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910001854 alkali hydroxide Inorganic materials 0.000 description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 238000007654 immersion Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- LDPWMGUFXYRDRG-UHFFFAOYSA-I niobium(5+) pentaacetate Chemical compound [Nb+5].CC([O-])=O.CC([O-])=O.CC([O-])=O.CC([O-])=O.CC([O-])=O LDPWMGUFXYRDRG-UHFFFAOYSA-I 0.000 description 2
- 150000007524 organic acids Chemical class 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 description 1
- 238000006237 Beckmann rearrangement reaction Methods 0.000 description 1
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 229910001413 alkali metal ion Inorganic materials 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 235000015165 citric acid Nutrition 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 235000011087 fumaric acid Nutrition 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000001630 malic acid Substances 0.000 description 1
- 235000011090 malic acid Nutrition 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910000484 niobium oxide Inorganic materials 0.000 description 1
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 description 1
- 238000001139 pH measurement Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 239000011975 tartaric acid Substances 0.000 description 1
- 235000002906 tartaric acid Nutrition 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Catalysts (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はニオブ酸粒子及びその製
造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to niobate particles and a method for producing the same.
【０００２】[0002]
【従来の技術】現在、化学工業においては、硫酸、塩
酸、リン酸等の鉱酸を触媒とするプロセスが数多く実施
されている。これらのプロセスでは、その鉱酸の分離回
収や廃酸処理の問題の他、その鉱酸に起因する装置腐食
及び製品着色等の問題がある。一方、これらの問題に対
処するために、鉱酸に代えて、分離回収の容易な固体酸
を用いる方法も提案されているが、一般に、固体酸は水
の存在する高温反応系では安定に存在することができ
ず、その固体酸機能を失活してしまうという問題があ
る。従来、ニオブ酸が固体酸として作用することは知ら
れているが、このものは水の存在する高温反応系ではそ
の固体酸機能を失活する。その原因としては、従来のニ
オブ酸粒子は不安定のため、水の存在下で加熱されると
他の物質に変質してしまうことが考えられている。ニオ
ブ酸粒子の安定性を向上させるためには、ニオブ粒子を
水の不存在下で高温で熱処理する方法が有効であるが、
この場合には、得られるニオブ酸粒子は固体酸機能が消
失してしまったもので、固体酸触媒としは使用できなく
なる。また、ニオブ酸粒子にリン酸を含浸させて使用す
る方法（特開昭６１−５４２４１号）も提案されている
が、この場合には、そのニオブ酸粒子の使用に際し、そ
のリン酸がニオブ酸粒子から離脱し、ニオブ酸粒子が再
び不安定化されるという問題がある。2. Description of the Related Art At present, in the chemical industry, many processes using a mineral acid such as sulfuric acid, hydrochloric acid or phosphoric acid as a catalyst are carried out. In these processes, in addition to the problem of separating and recovering the mineral acid and the treatment of waste acid, there are problems such as equipment corrosion and product coloring caused by the mineral acid. On the other hand, in order to deal with these problems, a method of using a solid acid that can be easily separated and recovered instead of the mineral acid has been proposed, but generally, the solid acid is stable in a high temperature reaction system in the presence of water. However, there is a problem that the solid acid function is deactivated. Conventionally, it is known that niobic acid acts as a solid acid, but this deactivates the solid acid function in a high temperature reaction system in the presence of water. As a cause for this, it is considered that conventional niobate particles are unstable, so that when they are heated in the presence of water, they are transformed into other substances. In order to improve the stability of the niobate particles, a method of heat treating the niobium particles at high temperature in the absence of water is effective,
In this case, the obtained niobate particles have lost the solid acid function and cannot be used as a solid acid catalyst. In addition, a method of impregnating niobate particles with phosphoric acid (Japanese Patent Application Laid-Open No. 61-54241) has also been proposed. In this case, when the niobate particles are used, the phosphoric acid is niobate. There is a problem that the niobate particles are released from the particles and destabilize the niobate particles again.
【０００３】従来、ニオブ酸粒子を得るために、シュウ
酸ニオブ水溶液に対し、アルカリ水溶液を添加する方法
が知られている（「Ｃａｔａｌｙｓｉｓ Ｔｏｄａ
ｙ」、Ｖｏｌ １６、２９１〜２９５（１９９３））。
このような従来法で得られるニオブ酸粒子は、シュウ酸
ニオブ粒子を含む微細なもので、その平均粒径は、通
常、１μｍより小さいものである。従って、このような
ニオブ酸粒子は、水中で容易にコロイド化し、その濾過
による分離は非常に困難であり、取扱い性の非常に悪い
ものである。また、このような従来法で得られるニオブ
酸粒子の耐水熱性は非常に悪く、３５０℃の耐水熱性試
験後には、そのＨｏが−３．０以下の酸量の１０％以上
が消失してしまう。従って、前記従来法で得られるニオ
ブ酸粒子は、そのままでは水の存在する高温反応系で用
いる固体酸触媒として適用することのできないものであ
る。Conventionally, in order to obtain niobate particles, a method of adding an alkaline aqueous solution to a niobium oxalate aqueous solution is known (“Catalysis Toda”).
y ", Vol 16, 291-295 (1993)).
The niobate particles obtained by such a conventional method are fine particles containing niobium oxalate particles, and the average particle diameter thereof is usually smaller than 1 μm. Therefore, such niobate particles are easily made into a colloid in water, their separation by filtration is very difficult, and their handleability is very poor. Further, the hydrothermal resistance of the niobate particles obtained by such a conventional method is very poor, and after the hydrothermal resistance test at 350 ° C., 10% or more of the acid amount having a Ho of −3.0 or less disappears. . Therefore, the niobate particles obtained by the conventional method cannot be applied as they are as a solid acid catalyst used in a high temperature reaction system in which water is present.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、水の存在下
での熱安定性が著しく向上した、固体酸触媒としてすぐ
れた機能を有するニオブ酸粒子及びその製造方法を提供
することをその課題とする。DISCLOSURE OF THE INVENTION It is an object of the present invention to provide niobate particles having excellent function as a solid acid catalyst, which has significantly improved thermal stability in the presence of water, and a method for producing the same. And
【０００５】[0005]
【課題を解決するための手段】本発明者らは、前記課題
を解決すべく鋭意研究を重ねた結果、本発明を完成する
に至った。The present inventors have completed the present invention as a result of intensive studies to solve the above problems.
【０００６】即ち、本発明によれば、１μｍ以上の平均
粒径を有するとともに、酸度関数Ｈｏ：−３．０以下の
酸量Ａを０．３５ｍｍｏｌ／ｇ以上有し、その酸量Ａの
うちの５０％以上が、Ｈｏ：−５．６以下の強酸量であ
り、かつ３５０℃の耐水熱性試験後の酸量Ａ減少率が１
０％以下であるニオブ酸粒子が提供される。That is, according to the present invention, in addition to having an average particle size of 1 μm or more and an acid amount A having an acidity function Ho: −3.0 or less of 0.35 mmol / g or more, of the acid amount A, 50% or more has a strong acid amount of Ho: -5.6 or less, and the acid amount A reduction rate after the hydrothermal resistance test at 350 ° C is 1
Niobate particles are provided that are 0% or less.
【０００７】また、本発明によれば、ニオブ化合物を溶
解する又は溶解していない１１より大きいｐＨのアルカ
リ性水溶液に、ニオブ化合物を溶解したｐＨ５以下の酸
性水溶液を撹拌下で混合液の平均ｐＨ降下率が０．２／
分以下になるように徐々に添加混合して、平均粒径が１
μｍ以上のニオブ酸粒子を含むｐＨ５．５〜１１．０の
混合液を得ることを特徴とするニオブ酸粒子の製造方法
が提供される。さらに、本発明によれば、平均粒径が１
以上のニオブ酸粒子を含むｐＨ５．５〜１１．０の混合
液に対し、ｐＨ５以下の酸性水溶液を添加混合する工程
と、１１より大きいｐＨのアルカリ性水溶液を添加混合
する工程をその混合液のｐＨを５．５〜１１．０の範囲
に保持しながら交互に繰返し行い、平均粒径が１μｍ以
上のニオブ酸粒子を含む混合液を得ることを特徴とする
ニオブ酸粒子の製造方法が提供される。さらにまた、本
発明によれば、平均粒径が1μｍ未満のニオブ酸粒子を
含むｐＨ５．５〜１１．０の混合液に対し、ｐＨ５以下
の酸性水溶液を添加混合する工程と、１１より大きいｐ
Ｈのアルカリ性水溶液を添加混合する工程を、その混合
液のｐＨを５．５〜１１．０の範囲に保持しながら交互
に繰返し行い、その際、前記アルカリ性水溶液及び酸性
水溶液の少なくとも一方にニオブ化合物を溶解させて、
平均粒径が１μｍ以上のニオブ酸粒子を含むｐＨ５．５
〜１１．０の混合液を得ることを特徴とするニオブ酸粒
子の製造方法が提供される。以下、本発明によるニオブ
酸粒子の製造方法について詳述する。Further, according to the present invention, the average pH drop of the mixed solution is obtained by stirring an acidic aqueous solution having a pH of 5 or less in which the niobium compound is dissolved in an alkaline aqueous solution having a pH of more than 11 in which the niobium compound is not dissolved. Rate is 0.2 /
Gradually add and mix so that the average particle size is 1 or less.
There is provided a method for producing niobate particles, which comprises obtaining a mixed solution having a pH of 5.5 to 11.0 and containing niobate particles having a size of not less than μm. Furthermore, according to the present invention, the average particle size is 1
The pH of the mixed solution includes a step of adding and mixing an acidic aqueous solution having a pH of 5 or less and a step of adding and mixing an alkaline aqueous solution having a pH of more than 11 to the mixed solution having a pH of 5.5 to 11.0 containing the above niobate particles. Are alternately repeated while maintaining the range of 5.5 to 11.0 to obtain a mixed solution containing niobate particles having an average particle diameter of 1 μm or more. . Furthermore, according to the present invention, a step of adding and mixing an acidic aqueous solution having a pH of 5 or less to a mixed solution having a pH of 5.5 to 11.0 containing niobate particles having an average particle size of less than 1 μm, and a p value greater than 11
The step of adding and mixing the alkaline aqueous solution of H is alternately repeated while maintaining the pH of the mixed solution in the range of 5.5 to 11.0, in which case at least one of the alkaline aqueous solution and the acidic aqueous solution contains a niobium compound. Dissolve
PH 5.5 including niobate particles having an average particle diameter of 1 μm or more
A method for producing niobate particles is provided, which is characterized by obtaining a mixed solution of 11.0. Hereinafter, the method for producing niobate particles according to the present invention will be described in detail.
【０００８】（第１の方法）本発明による第１のニオブ
酸粒子の製造方法は、ニオブ化合物を溶解する又は溶解
していない１１より大きいｐＨのアルカリ性水溶液に対
し、ニオブ化合物を溶解したｐＨ５以下の酸性水溶液を
徐々に添加する混合工程を含むものである。この場合、
原料ニオブ化合物は少なくとも酸性水溶液に溶解させる
ことが必要である。また、アルカリ性水溶液は、そのｐ
Ｈが１１より大きい範囲に保持される限り、このアルカ
リ性溶液にもニオブ化合物を好ましく溶解させることが
できる。そして、アルカリ性水溶液にニオブ化合物をあ
らかじめ溶解させることにより、少ない酸性水溶液量に
よって良好な性状のニオブ酸粒子を得ることができる。
また、アルカリ性水溶液に対する酸性水溶液の混合は、
最終的に得られる混合液のｐＨが５．５〜１１．０、好
ましくは６．０〜１０．０の範囲になるように行う。ア
ルカリ性水溶液としては、１１より大きいｐＨ、好まし
くは１１．５より大きいｐＨを有するアルカリ性を示す
溶液であればどのようなものでも使用可能であるが、一
般的には、水酸化ナトリウムや水酸化カリウム等の水酸
化アルカリの水溶液が用いられる。この場合、アルカリ
性水溶液中の水酸化アルカリの濃度は特に制約されない
が、一般には０．１〜１５規定、好ましくは０．２〜１
２規定である。本発明の好ましい１つの態様において
は、前記したように、アルカリ性水溶液にニオブ化合物
を溶解させるが、この場合のニオブ化合物としては、前
記アルカリ性水溶液に溶解し得るものであればどのよう
なものでも使用可能である。このようなニオブ化合物と
しては、例えば、ニオブ酸の他、シュウ酸ニオブや酢酸
ニオブ等の有機酸ニオブ等を挙げることができる。アル
カリ性水溶液中のニオブ化合物の濃度はその飽和濃度以
下であればよく、特に制約されないが、一般的には１〜
５０重量％、好ましくは２〜２０重量％である。(First Method) The first method for producing niobate particles according to the present invention comprises: a niobium compound-dissolved or undissolved alkaline aqueous solution having a pH of more than 11; It includes a mixing step of gradually adding the acidic aqueous solution. in this case,
The raw material niobium compound needs to be dissolved at least in an acidic aqueous solution. In addition, the alkaline aqueous solution is
The niobium compound can be preferably dissolved in this alkaline solution as long as H is maintained in the range of more than 11. Then, by preliminarily dissolving the niobium compound in the alkaline aqueous solution, it is possible to obtain niobate particles having good properties with a small amount of the acidic aqueous solution.
In addition, the mixing of the acidic aqueous solution with the alkaline aqueous solution,
The pH of the finally obtained mixed solution is adjusted to 5.5 to 11.0, preferably 6.0 to 10.0. As the alkaline aqueous solution, any alkaline solution having a pH of more than 11, preferably a pH of more than 11.5 can be used. Generally, sodium hydroxide or potassium hydroxide is used. An aqueous solution of alkali hydroxide is used. In this case, the concentration of alkali hydroxide in the alkaline aqueous solution is not particularly limited, but is generally 0.1 to 15 N, preferably 0.2 to 1
There are two rules. In a preferred embodiment of the present invention, as described above, the niobium compound is dissolved in the alkaline aqueous solution, but any niobium compound may be used as long as it is soluble in the alkaline aqueous solution. It is possible. Examples of such niobium compounds include niobate, and niobium oxalate and niobium acetate. The concentration of the niobium compound in the alkaline aqueous solution is not particularly limited as long as it is equal to or lower than its saturation concentration, but generally 1 to
It is 50% by weight, preferably 2 to 20% by weight.
【０００９】酸性水溶液としては、ｐＨ５以下の酸性を
示す溶液であればどのような溶液でも使用可能である
が、一般的には、硫酸、硝酸、リン酸等の無機酸や、シ
ュウ酸、酢酸、酒石酸、クエン酸、リンゴ酸、フマール
酸等の有機酸の水溶液が用いられる。また、ハロゲンを
含有する酸を用いた場合には、ハロゲンイオンが製品中
に残留することがあるので注意が必要である。酸性水溶
液中の酸濃度は特に制約されないが、一般には０．１〜
１５規定、好ましくは０．２〜１２規定である。本発明
においては、この酸性水溶液にニオブ化合物を溶解させ
るが、この場合のニオブ化合物としては、前記酸性水溶
液に溶解し得るものであればどのようなものでも使用可
能である。このようなニオブ化合物としては、例えば、
ニオブ酸の他、シュウ酸ニオブや酢酸ニオブ等の有機酸
ニオブ等を挙げることができる。酸性水溶液中のニオブ
化合物の濃度はその飽和濃度以下であればよく、特に制
約されないが、一般的には０．５〜３０重量％、好まし
くは１〜２０重量％である。As the acidic aqueous solution, any solution can be used as long as it shows an acidity of pH 5 or less. Generally, inorganic acids such as sulfuric acid, nitric acid and phosphoric acid, oxalic acid and acetic acid are used. An aqueous solution of an organic acid such as tartaric acid, citric acid, malic acid and fumaric acid is used. Further, when an acid containing halogen is used, caution is required because halogen ions may remain in the product. The acid concentration in the acidic aqueous solution is not particularly limited, but generally 0.1 to
It is 15 normal, preferably 0.2 to 12 normal. In the present invention, the niobium compound is dissolved in this acidic aqueous solution. In this case, any niobium compound can be used as long as it can be dissolved in the acidic aqueous solution. As such a niobium compound, for example,
In addition to niobate, niobium oxalate, niobium acetate, and other organic acid niobium can be used. The concentration of the niobium compound in the acidic aqueous solution is not particularly limited as long as it is equal to or lower than its saturation concentration, but is generally 0.5 to 30% by weight, preferably 1 to 20% by weight.
【００１０】本発明においては、ニオブ化合物を溶解す
る又は溶解していないアルカリ性水溶液に対し、ニオブ
化合物を溶解した酸性水溶液を撹拌下で混合し、ニオブ
酸沈殿溶液からなる混合液を得るが、この場合の混合液
のｐＨは、ニオブ酸の沈殿形成領域内の５．５〜１１．
０、好ましくは６．０〜１１．０の範囲に調整する。ま
た、この場合の混合液のｐＨ調整は、混合液のｐＨが高
い方から低い方に変化するように行うことが必要であ
る。このためには、アルカリ性水溶液に酸性水溶液を徐
々に添加すればよい。アルカリ性水溶液に酸性水溶液を
一時に加えてしてしまうと、ニオブ酸の成長とは別に新
しいニオブ酸の核が生成してしまうとともに、混合液中
に、ニオブ酸の沈殿領域よりも低いｐＨ範囲（ｐＨ５．
５未満）の部分が局部的に生じ、所望するニオブ酸粒子
以外のニオブ化合物の粒子、例えば、酸性水溶液として
シュウ酸ニオブ水溶液を用いるときには、そのシュウ酸
ニオブが微粒子として析出する。そして、このようなシ
ュウ酸ニオブ微粒子を含むニオブ酸粒子は、耐水熱性の
良い製品を与えない。本発明においては、酸性水溶液の
添加速度は、混合液の平均ｐＨ降下率が０．２／分以
下、好ましくは０．０１〜０．１／分の範囲になるよう
に、酸性水溶液の添加速度を調整するのがよい。混合液
の温度は常温〜１００℃、好ましくは常温〜９５℃に保
持するのがよい。In the present invention, an alkaline aqueous solution in which the niobium compound is dissolved or not dissolved is mixed with an acidic aqueous solution in which the niobium compound is dissolved under stirring to obtain a mixed solution consisting of a niobate precipitation solution. In this case, the pH of the mixed solution is 5.5 to 11.
It is adjusted to 0, preferably 6.0 to 11.0. Further, in this case, it is necessary to adjust the pH of the mixed solution so that the pH of the mixed solution changes from a higher value to a lower value. For this purpose, the acidic aqueous solution may be gradually added to the alkaline aqueous solution. If an acidic aqueous solution is added to the alkaline aqueous solution at a time, new niobic acid nuclei are generated in addition to the growth of niobic acid, and a pH range lower than the precipitation region of niobic acid (pH 5.
(Less than 5) locally occurs, and particles of niobium compounds other than the desired niobate particles, for example, when an aqueous niobium oxalate solution is used as the acidic aqueous solution, the niobium oxalate precipitates as fine particles. The niobate particles containing such fine niobium oxalate particles do not give a product having good hydrothermal resistance. In the present invention, the addition rate of the acidic aqueous solution is such that the average pH drop rate of the mixed solution is 0.2 / min or less, preferably 0.01 to 0.1 / min. It is better to adjust. The temperature of the mixed solution is maintained at room temperature to 100 ° C, preferably room temperature to 95 ° C.
【００１１】また、本発明においてアルカリ性水溶液に
酸性水溶液を添加混合する場合、その混合によって得ら
れた混合液（ニオブ酸沈殿溶液）に対して、ニオブ化合
物を溶解したｐＨ５以下の酸性水溶液及び／又はニオブ
化合物を溶解する又は溶解していない１１より大きいア
ルカリ性水溶液を、その混合液のｐＨをｐＨ５．５〜１
１．０のニオブ酸沈殿領域に保持しながら、添加するこ
とができる。このようにして、ニオブ酸粒子の成長した
粒子サイズの大きいニオブ酸粒子を得ることができる。
この場合の酸性水溶液及びアルカリ性水溶液の添加は、
混合液の平均ｐＨ降下率が０．２／分以下になるように
行うのがよい。When an acidic aqueous solution is added to and mixed with an alkaline aqueous solution in the present invention, an acidic aqueous solution having a pH of 5 or less in which a niobium compound is dissolved is added to a mixed solution (niobic acid precipitation solution) obtained by the mixing. An alkaline aqueous solution having a niobium compound dissolved or not dissolved therein and having a pH of 11 or more is adjusted to pH 5.5 to 1
It can be added while being maintained in the niobate precipitation region of 1.0. In this way, niobate particles having a large particle size obtained by growing niobate particles can be obtained.
In this case, the addition of the acidic aqueous solution and the alkaline aqueous solution is
It is preferable that the average pH drop rate of the mixed solution is 0.2 / min or less.
【００１２】（第２の方法）本発明による第２のニオブ
酸粒子の製造方法は、ニオブ酸粒子を含むｐＨ５．５〜
１１．０の混合液に対し、混合液のｐＨを５．５〜１
０．５のニオブ酸沈殿領域内に保持しながら、アルカリ
性水溶液を添加混合する工程と酸性水溶液を添加混合す
る工程を交互に繰返し行う操作を含む。このような操作
によって、粒子サイズの均一なニオブ酸粒子を得ること
ができる。この場合のアルカリ性水溶液と酸性水溶液の
交互添加による混合液のｐＨ変動は２以上、好ましくは
４以上に変動させるのがよい。また、この場合の酸性水
溶液及びアルカリ性水溶液の添加速度は特に制約されな
い。(Second Method) A second method for producing niobate particles according to the present invention is a method of producing niobate particles containing a pH of 5.5 to 5.5.
The pH of the mixed solution is 5.5 to 1 with respect to the mixed solution of 11.0.
An operation of alternately repeating the step of adding and mixing the alkaline aqueous solution and the step of adding and mixing the acidic aqueous solution while maintaining the niobic acid precipitation region of 0.5 is included. By such an operation, niobate particles having a uniform particle size can be obtained. In this case, the pH fluctuation of the mixed solution by alternate addition of the alkaline aqueous solution and the acidic aqueous solution should be changed to 2 or more, preferably 4 or more. Further, the addition rates of the acidic aqueous solution and the alkaline aqueous solution in this case are not particularly limited.
【００１３】前記ニオブ酸粒子を含む原料混合液は、ア
ルカリ性水溶液に酸性水溶液を添加混合する方法で得ら
れたものであれば、各種の方法で得られたものであるこ
とができる。この場合、原料混合液中のニオブ酸粒子の
粒径は特に制約されない。本発明で用いる原料混合液
は、前記した第１の方法で得られた平均粒径が１μｍ以
上のニオブ酸粒子を含む混合液であることができる。こ
のような原料混合液に対してアルカリ性水溶液と酸性水
溶液を交互に繰返し添加混合すると、粒径の揃ったニオ
ブ酸粒子を得ることができる。また、原料混合液に対し
て添加するアルカリ性水溶液及び酸性水溶液の少なくと
も一方にニオブ化合物を溶解させることにより、原料混
合液に含まれるニオブ酸粒子より大きな粒径に粒子成長
した粒径分布のシャープなニオブ酸粒子を得ることがで
きる。また、本発明で用いる原料混合液は、平均粒径が
１μｍ未満のニオブ酸粒子を含む混合液であることがで
きる。このような混合液は、混合するアルカリ性水溶液
と酸性水溶液の少なくとも一方にニオブ化合物を溶解さ
せたものを用い、アルカリ性水溶液に対して酸性水溶液
を添加混合することによって得ることができる。この場
合、アルカリ性水溶液に対する酸性水溶液の添加速度は
特に制約されない。このような平均粒径が１μｍ以下の
ニオブ酸粒子を含む混合液に対してアルカリ性水溶液と
酸性水溶液を交互に添加する場合、それらの水溶液の少
なくとも一方にニオブ化合物を溶解させることにより、
原料混合液に含まれるニオブ酸粒子よりも大きな粒径に
粒子成長し、しかも粒径の揃った平均粒径が１μｍ以上
のニオブ酸粒子を得ることができる。The raw material mixed solution containing the niobate particles can be obtained by various methods as long as it is obtained by a method of adding and mixing an acidic aqueous solution to an alkaline aqueous solution. In this case, the particle size of the niobate particles in the raw material mixture is not particularly limited. The raw material mixed solution used in the present invention can be a mixed solution containing niobate particles having an average particle size of 1 μm or more obtained by the above-mentioned first method. By repeatedly adding and mixing an alkaline aqueous solution and an acidic aqueous solution to such a raw material mixture, niobic acid particles having a uniform particle size can be obtained. Further, by dissolving the niobium compound in at least one of the alkaline aqueous solution and the acidic aqueous solution to be added to the raw material mixed solution, the niobate particles contained in the raw material mixed solution have a larger particle size than the niobate particles contained in the raw material mixed solution, resulting in a sharp particle size distribution. Niobate particles can be obtained. The raw material mixture used in the present invention can be a mixture containing niobate particles having an average particle size of less than 1 μm. Such a mixed solution can be obtained by using a solution of a niobium compound dissolved in at least one of an alkaline aqueous solution and an acidic aqueous solution to be mixed, and adding and mixing the acidic aqueous solution to the alkaline aqueous solution. In this case, the addition rate of the acidic aqueous solution to the alkaline aqueous solution is not particularly limited. When an alkaline aqueous solution and an acidic aqueous solution are alternately added to a mixed solution containing niobate particles having an average particle diameter of 1 μm or less, by dissolving the niobium compound in at least one of the aqueous solutions,
It is possible to obtain niobate particles having a particle size larger than that of the niobate particles contained in the raw material mixture and having an average particle size of 1 μm or more.
【００１４】図１に混合液のｐＨ変動を伴うｐＨ変動法
によるニオブ酸粒子製造工程のフローシートの一例を示
す。図１において、１及び２は容器を示し、３及び４は
混合器を示し、５及び６はポンプを示す。この図１に示
したフローシートに従ってニオブ酸粒子を製造するに
は、先ず容器１にｐＨ７．５〜１１．０のアルカリ性に
保持されたニオブ酸粒子を含む混合液（ニオブ酸沈殿溶
液）をライン１５を介して充填する。次に、この混合液
を移送ポンプ５により、流量調節弁７で流量を制御し、
混合器３に供給する。他方、同時に酸性水溶液供給ライ
ン１３より、酸性水溶液を酸性側ｐＨ制御弁１１を通し
て混合器３に供給し、アルカリ性混合液に対して均一に
混合する。この場合の酸性水溶液の添加速度は特に制約
されない。均一に混合された２液はこれを酸性側ｐＨ検
出器９によってｐＨ測定し、その混合液のｐＨを酸性側
ｐＨ制御弁１１により所定のｐＨに制御し、酸性側容器
２に送る。酸性側にｐＨ調節された混合液は容器２にお
いて一定時間保持される。この場合の保持時間は系内の
ｐＨが均一になる時間で、通常０．５〜３０分、好まし
くは１〜１０分であり、その保持温度は常温〜１００
℃、好ましくは常温〜９５℃である。次に、容器２に保
持された酸性側にｐＨ調節された混合液は、これを移送
ポンプ６により流量調節弁８で流量制御し、混合器４に
供給する。一方、同時にアルカリ性水溶液をアルカリ性
水溶液供給ライン１４よりアルカリ性側ｐＨ制御弁１２
を通じて混合器４に供給し、２液を均一に混合する。こ
の場合のアルカリ性水溶液の添加速度は特に制約されな
い。この混合液のｐＨはアルカリ性側ｐＨ検出器１０に
よってｐＨ測定し、アルカリ性側ｐＨ制御弁１２によっ
て所定のｐＨ値に制御する。そして、このアルカリ性側
にｐＨ調節された混合液は容器１において一定時間保持
される。この場合の保持時間は系内のｐＨが均一になる
時間で通常０．５〜３０分、好ましくは１〜１０分であ
り、その保持温度は常温〜１００℃、好ましくは常温〜
９５℃である。次に、このアルカリ性側にｐＨ調節され
た混合液は前記と同様にライン１３からの酸性水溶液に
よって酸性側にｐＨが調節され、容器２に移送される。
このサイクルを繰返すことによって粒子サイズの揃った
ニオブ酸粒子が製造される。ニオブ酸粒子を含む混合液
は、これをライン１６を介して回収する。また、前記ア
ルカリ性溶液と酸性溶液の少なくとも一方にニオブ化合
物を溶解させることにより、粒子成長した、粒子サイズ
の揃ったニオブ酸粒子を得ることができる。FIG. 1 shows an example of a flow sheet of a niobate particle production process by a pH variation method involving pH variation of a mixed solution. In FIG. 1, 1 and 2 are containers, 3 and 4 are mixers, and 5 and 6 are pumps. In order to produce niobate particles according to the flow sheet shown in FIG. 1, first, a container 1 is lined with a mixed solution (niobate precipitation solution) containing niobate particles kept alkaline at pH 7.5 to 11.0. Fill via 15. Next, the flow rate of this mixed solution is controlled by the transfer pump 5 and the flow rate control valve 7,
Supply to the mixer 3. On the other hand, at the same time, the acidic aqueous solution is supplied from the acidic aqueous solution supply line 13 to the mixer 3 through the acidic pH control valve 11 to uniformly mix the alkaline mixed solution. The addition rate of the acidic aqueous solution in this case is not particularly limited. The two liquids that have been uniformly mixed are subjected to pH measurement by an acidic pH detector 9, the pH of the mixed liquid is controlled to a predetermined pH by an acidic pH control valve 11, and then sent to the acidic container 2. The mixed solution whose pH is adjusted to the acidic side is held in the container 2 for a certain period of time. The holding time in this case is a time for the pH in the system to become uniform, and is usually 0.5 to 30 minutes, preferably 1 to 10 minutes, and the holding temperature is from room temperature to 100.
C., preferably room temperature to 95.degree. Next, the pH of the mixed liquid held in the container 2 and adjusted to the acidic side is controlled by the transfer pump 6 by the flow control valve 8 and supplied to the mixer 4. On the other hand, at the same time, the alkaline aqueous solution is fed from the alkaline aqueous solution supply line 14 to the pH control valve 12 on the alkaline side.
To the mixer 4 to uniformly mix the two liquids. In this case, the addition rate of the alkaline aqueous solution is not particularly limited. The pH of this mixed solution is measured by the alkaline pH detector 10 and controlled by the alkaline pH control valve 12 to a predetermined pH value. Then, the mixed solution whose pH is adjusted to the alkaline side is held in the container 1 for a certain period of time. The holding time in this case is usually 0.5 to 30 minutes, preferably 1 to 10 minutes when the pH in the system becomes uniform, and the holding temperature is room temperature to 100 ° C., preferably room temperature to
95 ° C. Next, the pH of the mixed solution whose pH has been adjusted to the alkaline side is adjusted to the acidic side by the acidic aqueous solution from the line 13 as described above, and is transferred to the container 2.
By repeating this cycle, niobate particles having a uniform particle size are manufactured. The mixed liquid containing niobic acid particles is recovered via the line 16. Further, by dissolving a niobium compound in at least one of the alkaline solution and the acidic solution, it is possible to obtain niobate particles having a uniform particle size and having grown particles.
【００１５】本発明において、混合液のｐＨを変動させ
る回数（ｐＨ変動回数）、即ち、混合液を、容器１から
容器２に移送した後、再び容器１に移送させる操作サイ
クルの回数は、少なくとも１回、通常、２〜５０回であ
る。操作サイクルの回数は、得られるニオブ酸粒子の粒
子径、細孔径及び細孔容積に影響を与える。一般的にｐ
Ｈ変動回数の増加に伴い、得られるニオブ酸の粒子径は
均一になり、かつ細孔径が大きくなる。従ってｐＨ変動
の回数は所望するニオブ酸粒子の性状によって適宜選択
する。極めて大細孔径のニオブ酸粒子を得る場合には、
５０回以上となることもあり得る。前記のようにして得
られるニオブ酸粒子を含む混合液は、これを固液分離処
理して、ニオブ酸粒子を回収する。この場合、固液分離
処理に供する混合液は、ニオブ酸粒子が最も安定に存在
するｐＨ領域である６．０〜１０．０の範囲のｐＨに調
節するのが好ましい。固液分離法としては、慣用の方
法、例えば、濾過法や、沈降法、遠心分離法等を採用す
ることができる。In the present invention, the number of times the pH of the mixed solution is changed (the number of pH changes), that is, the number of operation cycles for transferring the mixed solution from the container 1 to the container 2 and then again to the container 1 is at least Once, usually 2 to 50 times. The number of operation cycles affects the particle size, pore size and pore volume of the obtained niobate particles. Generally p
As the number of H fluctuations increases, the particle size of the obtained niobic acid becomes uniform and the pore size increases. Therefore, the number of pH changes is appropriately selected depending on the desired properties of the niobate particles. When obtaining niobate particles with an extremely large pore size,
It may be 50 times or more. The mixed solution containing niobate particles obtained as described above is subjected to solid-liquid separation treatment to recover niobate particles. In this case, it is preferable that the mixed liquid used for the solid-liquid separation treatment is adjusted to have a pH in the range of 6.0 to 10.0, which is the pH range in which the niobate particles are most stably present. As the solid-liquid separation method, a conventional method, for example, a filtration method, a sedimentation method, a centrifugation method or the like can be adopted.
【００１６】このようにして得られるニオブ酸粒子は慣
用の方法によって後処理され、固体酸としての機能を有
するニオブ酸粒子とされる。この固体酸機能を付与する
ためのニオブ酸粒子の後処理は、一般的には、固液分離
処理により得られるニオブ酸粒子を水洗する工程と、カ
チオン交換処理する工程を含む。カチオン交換処理は、
ニオブ酸塩としてニオブ酸粒子に結合しているアルカリ
金属イオンを水素イオンに交換する工程であり、これに
より固体酸としての機能を示すニオブ酸粒子を得ること
ができる。また、カチオン交換処理は、ニオブ酸粒子を
硝酸水溶液や、硫酸水溶液等の酸性水溶液と接触させる
ことによって行うことができる。この場合、酸性水溶液
にハロゲンを含む酸を用いるとハロゲンイオンが残留す
ることがあるので注意が必要である。ニオブ酸粒子を水
洗する場合、洗浄水としては、必要に応じて４０〜１０
０℃に加温した加温水を用いることができ、好ましくは
沸騰水を用いる。また、ニオブ酸粒子をカチオン交換処
理する場合、酸性水溶液としては４０〜１００℃に加温
した溶液を用いることができる。水洗処理及びカチオン
交換処理されたニオブ酸粒子中に残留するアルカリの量
は、乾燥状態のニオブ酸粒子１ｇあたり、１万分の５モ
ル以下、好ましくは１０万分の５モル以下に規定するの
がよい。ニオブ酸粒子に残留するアルカリは、ニオブ酸
粒子の強い酸性点を中和し、ニオブ酸粒子の固体酸機能
を低減させる。また、ニオブ酸粒子中には、アンモニウ
ムイオンや、他の金属イオン等の水素イオン以外の陽イ
オンの存在も好ましくない。これらの陽イオンも、ニオ
ブ酸粒子の固体酸としての機能を低減させる。従って、
本発明で反応原料として用いる水、アルカリ性物質、酸
性物質等は、いずれも、他の金属イオンやアンモニウム
イオン等の不純物陽イオンの存在しない、ハロゲン含有
量の少ない高純度品を用いるのが好ましい。The niobate particles thus obtained are post-treated by a conventional method to give niobate particles having a function as a solid acid. The post-treatment of the niobate particles for imparting the solid acid function generally includes a step of washing the niobate particles obtained by the solid-liquid separation treatment with water and a step of cation exchange treatment. The cation exchange treatment is
This is a step of exchanging alkali metal ions bonded to niobate particles as niobate for hydrogen ions, whereby niobate particles exhibiting a function as a solid acid can be obtained. The cation exchange treatment can be performed by bringing the niobate particles into contact with an aqueous nitric acid solution or an acidic aqueous solution such as an aqueous sulfuric acid solution. In this case, when an acid containing halogen is used in the acidic aqueous solution, halogen ions may remain, so care must be taken. When the niobate particles are washed with water, the washing water may be 40 to 10 if necessary.
Warmed water heated to 0 ° C. can be used, and boiling water is preferably used. When the niobate particles are subjected to cation exchange treatment, a solution heated to 40 to 100 ° C. can be used as the acidic aqueous solution. The amount of alkali remaining in the niobate particles which have been washed with water and subjected to cation exchange treatment is preferably 5 mol / 10,000 or less, and more preferably 5 mol / 100,000 or less, per 1 g of dry niobate particles. . The alkali remaining on the niobate particles neutralizes the strong acid points of the niobate particles and reduces the solid acid function of the niobate particles. The presence of cations other than hydrogen ions such as ammonium ions and other metal ions in the niobate particles is also not preferable. These cations also reduce the function of the niobate particles as a solid acid. Therefore,
As the water, alkaline substance, acidic substance and the like used as the reaction raw material in the present invention, it is preferable to use a high-purity product having a small halogen content and free of impurity cations such as other metal ions and ammonium ions.
【００１７】ニオブ酸粒子は、通常の方法により、球
状、ペレット状、筒状、ハニカム状等の各種の形状に成
形することができる。このニオブ酸粒子の成形は、前記
した水洗処理やカチオン交換処理の前又は後に行うこと
ができる他、ニオブ酸粒子の乾燥後あるいは焼成後等の
任意の時点において行うことができる。ニオブ酸粒子又
はその成形品は、その中に含まれている水分を除去し、
脱水物を得るために、乾燥あるいは焼成することができ
る。この場合の乾燥は、室温〜１８０℃の温度におい
て、減圧乾燥や送風乾燥により行うことができる。ま
た、焼成は、１８０〜５００℃、好ましくは２００〜４
５０℃の温度で行うことができる。この場合の焼成は空
気中で行うことができる。焼成温度が５００℃を超える
と、ニオブ酸粒子が酸化ニオブへの相変化が起り、その
酸点が消失するので、５００℃以下の焼成温度の使用が
好ましい。The niobate particles can be formed into various shapes such as a spherical shape, a pellet shape, a cylindrical shape, and a honeycomb shape by a usual method. The molding of the niobate particles can be performed before or after the above-mentioned water washing treatment or cation exchange treatment, and can be performed at any time after the niobate particles are dried or calcined. Niobate particles or molded articles thereof remove the water contained therein,
It can be dried or calcined to obtain the dehydrated product. Drying in this case can be performed by vacuum drying or blast drying at a temperature of room temperature to 180 ° C. The firing is performed at 180 to 500 ° C., preferably 200 to 4
It can be carried out at a temperature of 50 ° C. The firing in this case can be performed in air. When the firing temperature exceeds 500 ° C., the niobate particles undergo a phase change to niobium oxide and the acid sites disappear, so it is preferable to use a firing temperature of 500 ° C. or lower.
【００１８】本発明により得られるニオブ酸粒子は、従
来のニオブ酸粒子とは異なり、粒径の大きなもので、そ
の平均粒径は、１μｍ以上、通常、２〜５０μｍの範囲
にある。従って、本発明のニオブ酸粒子は、混合液から
の分離回収が容易である上、その水洗処理やカチオン交
換処理も容易であるという利点を有する。従来のニオブ
酸粒子は、その平均粒径が、通常、１μｍ未満という微
細なもので、水中ではコロイド化してしまい、その固液
分離や、水洗処理、カチオン交換処理に大きな困難を伴
うが、本発明によるニオブ酸粒子の場合には、このよう
な困難を生じない。本発明のニオブ酸粒子は、１μｍ目
開きの濾紙によって濾過分離可能である。特にｐＨ変動
法で得られるニオブ酸粒子はこれを１μｍ目開きの濾紙
によって濾過するときに、濾液側へのニオブ酸粒子の流
出は全く観察されなかった。The niobate particles obtained by the present invention have a large particle size, unlike conventional niobate particles, and their average particle size is 1 μm or more, usually in the range of 2 to 50 μm. Therefore, the niobate particles of the present invention have an advantage that they can be easily separated and recovered from the mixed solution, and can be easily washed with water or cation exchanged. Conventional niobate particles have a fine average particle size of usually less than 1 μm and are colloided in water, which causes great difficulties in solid-liquid separation, water washing treatment, and cation exchange treatment. In the case of the niobate particles according to the invention, such difficulties do not occur. The niobate particles of the present invention can be separated by filtration with a filter paper having an opening of 1 μm. In particular, when the niobate particles obtained by the pH variation method were filtered through a filter paper having an opening of 1 μm, no outflow of the niobate particles to the filtrate was observed.
【００１９】また、本発明のニオブ酸粒子は、水の存在
下における熱安定性において著しく向上したもので、耐
水熱試験によっても、結晶粒子の変質はなく、その固体
酸としての機能が低下するようなことはない。本発明の
ニオブ酸粒子の酸度関数であるＨｏ（ハメット指数）が
−０．３以下の酸量Ａは３００℃焼成において０．３５
ｍｍｏｌ／ｇ以上、通常、０．３５〜０．７０ｍｍｏｌ
／ｇと多く、しかもその酸量Ａに対するＨｏが−５．６
以下の強酸量Ｂの割合は５０％以上、通常、５５〜８５
％であるが、３５０℃の耐水熱試験後においてもその酸
量Ａの低減は、通常、１０％以下と極くわずかである。
なお、本明細書におけるＨｏ（ハメット指数）は、酸度
関数で、触媒学会編「触媒実験ハンドブック」（１９８
６年出版、講談社サイエンティフィク）、第１７２頁に
記載の「Ｂｅｎｅｓｉ法」により測定されたものであ
る。この場合、Ｈｏが小さい程酸強度が大きいことを意
味する。本明細書では、Ｈｏが−３．０以下の酸量をニ
オブ酸粒子の酸量とし、Ｈｏが−５．６以下の酸量を強
酸量とした。Further, the niobate particles of the present invention are remarkably improved in thermal stability in the presence of water, and even in the hydrothermal resistance test, the crystal particles are not deteriorated and their function as a solid acid is lowered. There is no such thing. The acid amount A having a Ho (Hammett index), which is an acidity function of the niobate particles of the present invention, of -0.3 or less is 0.35 at 300 ° C. firing.
mmol / g or more, usually 0.35 to 0.70 mmol
/ G, and Ho for the acid amount A is -5.6.
The ratio of the following strong acid amount B is 50% or more, usually 55 to 85
%, The decrease in the acid amount A even after the hydrothermal resistance test at 350 ° C. is usually as small as 10% or less.
In addition, Ho (Hammett index) in the present specification is an acidity function, and is referred to as "catalyst experiment handbook" (198) edited by The Catalysis Society of Japan.
6 years, Kodansha Scientific), page 172, "Benesi method". In this case, the smaller Ho means the higher acid strength. In the present specification, an acid amount having Ho of −3.0 or less is defined as an acid amount of niobate particles, and an acid amount of Ho being −5.6 or less is defined as a strong acid amount.
【００２０】本発明のニオブ酸粒子は、前記したよう
に、その平均粒径は１μｍ以上と大きいものであり、ま
たそのＨｏが−３．０以下の酸量Ａも３００℃焼成にお
いて０．３５ｍｍｏｌ／ｇ以上と大きい値を示すもので
ある。本発明において、ｐＨ変動法により得られるニオ
ブ酸粒子は、シャープな粒径分布を有し、固体酸触媒と
して特にすぐれた性能を有する。As described above, the niobate particles of the present invention have a large average particle size of 1 μm or more, and the acid amount A of which Ho is −3.0 or less is 0.35 mmol when calcined at 300 ° C. / G or more, which is a large value. In the present invention, the niobate particles obtained by the pH variation method have a sharp particle size distribution and have particularly excellent performance as a solid acid catalyst.
【００２１】[0021]
【発明の効果】本発明のニオブ酸粒子は、すぐれた固体
酸機能を有し、固体酸触媒として各種の反応に用いるこ
とができ、特に、通常の固体酸を用いることができない
高温で水が関与する反応系に用いる固体酸触媒として有
利に用いることができる。また、本発明のニオブ酸粒子
は、複合触媒の一成分として用いることができる。例え
ば、本発明のニオブ酸粒子は、エチレン等のオレフィン
の水和によるアルコール合成用触媒又はその触媒成分と
して有利に用いられる他、加水分解反応、エステル化反
応、ベックマン転移反応における触媒又は触媒成分とし
て用いることができる。本発明によるニオブ酸粒子の製
造方法によれば、前記した固体酸触媒としてすぐれた機
能を有するニオブ酸粒子を効率よく得ることができる。INDUSTRIAL APPLICABILITY The niobate particles of the present invention have an excellent solid acid function and can be used in various reactions as a solid acid catalyst. It can be advantageously used as a solid acid catalyst used in the reaction system involved. Further, the niobate particles of the present invention can be used as one component of a composite catalyst. For example, the niobate particles of the present invention can be advantageously used as a catalyst for alcohol synthesis by hydration of olefins such as ethylene or a catalyst component thereof, and also as a catalyst or catalyst component in hydrolysis reaction, esterification reaction, Beckmann rearrangement reaction. Can be used. According to the method for producing niobate particles of the present invention, it is possible to efficiently obtain niobate particles having an excellent function as the solid acid catalyst described above.
【００２２】[0022]
【実施例】次に本発明を実施例によりさらに詳細に示
す。EXAMPLES The present invention will now be described in more detail by way of examples.
【００２３】実施例１ 水５リットルにシュウ酸１２５ｇを溶解させたシュウ酸
水溶液（ｐＨ：１．０）にシュウ酸ニオブ２５０ｇを溶
解させた後、不純物を濾過分離してシュウ酸ニオブ水溶
液（ｐＨ：１．２）を調製した。次に、このシュウ酸ニ
オブ水溶液５リットルを、撹拌下（ｒｐｍ：２００）に
おいて、４Ｎの水酸化カリウム水溶液（ｐＨ：１４）
１．３５リットルに添加し、ｐＨ７．９８の混合液（沈
殿溶液）を得た。この場合、シュウ酸ニオブ溶液の添加
は徐々に行い、混合液の平均ｐＨ降下が０．２／分以下
になるように添加した。このようにして得た混合液中に
含まれる沈殿物を濾別回収した後、得られた沈殿物を
０．１Ｎの硝酸５リットルを用いて２回浸漬洗浄し、次
いで５リットルの煮沸水を用いて２回浸漬洗浄した。こ
のようにして得られたニオブ酸粒子の平均粒径は３μｍ
であった。このものを１１０℃で乾燥後、３００℃で空
気中で焼成して、ニオブ酸粒子の脱水物を得た。Example 1 250 g of niobium oxalate was dissolved in an aqueous solution of oxalic acid (pH: 1.0) in which 125 g of oxalic acid was dissolved in 5 liters of water, and then impurities were separated by filtration to remove niobium oxalate solution (pH). : 1.2) was prepared. Then, 5 liters of this niobium oxalate aqueous solution was stirred (rpm: 200) while stirring with a 4N potassium hydroxide aqueous solution (pH: 14).
It was added to 1.35 liters to obtain a mixed solution (precipitation solution) having a pH of 7.98. In this case, the niobium oxalate solution was gradually added so that the average pH drop of the mixed solution was 0.2 / min or less. After the precipitate contained in the thus obtained mixed solution was collected by filtration, the obtained precipitate was washed by immersion in 5 L of 0.1 N nitric acid twice, and then 5 L of boiling water was added. It was used for immersion cleaning twice. The average particle size of the niobate particles thus obtained is 3 μm.
Met. This was dried at 110 ° C. and then calcined at 300 ° C. in air to obtain a dehydrated product of niobate particles.
【００２４】次に、このようにして得たニオブ酸粒子の
脱水物について、その酸量、及びその耐水熱性試験後の
酸量及び酸量減少率を以下のようにして求めた。その結
果を表１に示す。 （酸量）酸量の測定は、触媒学会編「触媒実験ハンドブ
ック」（１９８６年出版、講談社サイエンティフィク）
第１７２頁に記載のＢｅｎｅｓｉ法により行った。この
場合、Ｈｏが−３．０以下の酸量を固体酸量Ａとし、Ｈ
ｏが−５．６以下の酸量を強酸量Ｂとした。 （耐水熱性試験）内径が９．５ｍｍのステンレス製パイ
プに、試料１０ｇを充填して充填層を作り、この充填層
に対し、３５０℃に加熱したスチームを１５リットル／
時間の流速で２４時間流通させた後、その試料を取出
し、その酸量Ａ及び強酸量Ｂを測定するとともに、酸量
Ａ減少率を求めた。この場合の酸量Ａ減少率は次式によ
って算出した。 酸量Ａ減少率＝｛Ａ（Ｉ）−Ａ（II）／Ａ（Ｉ）｝×１
００（％） Ａ（Ｉ）：耐水熱性試験前の試料の酸量 Ｂ（II）：耐水熱性試験後の試料の酸量 なお、本明細書で言う耐水熱試験とは、前記の試験を意
味するものである。Next, the acid content of the dehydrated niobate particles thus obtained and the acid content and the acid content reduction rate after the hydrothermal resistance test were determined in the following manner. The results are shown in Table 1. (Amount of acid) The amount of acid can be measured by "Catalysis Experiment Handbook" edited by The Catalysis Society of Japan (Published in 1986, Kodansha Scientific).
The Benesi method described on page 172 was used. In this case, the acid amount having Ho of −3.0 or less is defined as the solid acid amount A, and H
The amount of acid having o of -5.6 or less was defined as the strong acid amount B. (Hydrothermal resistance test) A stainless steel pipe having an inner diameter of 9.5 mm was filled with 10 g of a sample to form a packed layer, and 15 liter of steam heated to 350 ° C. was added to the packed layer.
After flowing at a flow rate of 24 hours, the sample was taken out, the acid amount A and the strong acid amount B were measured, and the acid amount A decrease rate was obtained. The rate of decrease of the acid amount A in this case was calculated by the following equation. Acid amount A decrease rate = {A (I) -A (II) / A (I)} × 1
00 (%) A (I): Acid amount of sample before hydrothermal resistance test B (II): Acid amount of sample after hydrothermal resistance test The hydrothermal resistance test referred to in the present specification means the above test. To do.
【００２５】[0025]
【表１】 [Table 1]
【００２６】実施例２ 実施例１において、シュウ酸ニオブ水溶液の添加速度を
種々変化させた以外は同様にして実験を行った。表２に
ニオブ酸粒子の平均粒径及びその脱水物の耐水熱性試験
前後の酸量Ａを示す。Example 2 An experiment was conducted in the same manner as in Example 1 except that the addition rate of the niobium oxalate aqueous solution was changed variously. Table 2 shows the average particle size of the niobate particles and the acid amount A before and after the hydrothermal resistance test of the dehydrated product.
【００２７】[0027]
【表２】 [Table 2]
【００２８】実施例３ 実施例１で示したシュウ酸ニオブ水溶液（ｐＨ１．２
０）１．１リットルを、実施例１で示したＫＯＨ水溶液
（ｐＨ１４．００）０．６２５リットルに添加混合し
て、ｐＨ１４の透明液を得た。次に、この混合液に対し
て、シュウ酸ニオブ水溶液（ｐＨ１．２０）とＫＯＨ水
溶液（ｐＨ１４．００）を表３に示す添加量で交互に添
加混合して、最終的にｐＨ７．８５の混合液（沈殿物溶
液）を得た。この場合、シュウ酸ニオブ水溶液およびＫ
ＯＨ水溶液の添加は、すみやかに行った。また、添加後
それぞれのｐＨで３分間保持した。表３には、シュウ酸
ニオブ水溶液とＫＯＨ水溶液の添加後の混合液のｐＨを
あわせて示す。Example 3 The niobium oxalate aqueous solution (pH 1.2) shown in Example 1 was used.
0) 1.1 liter was added and mixed with 0.625 liter of the KOH aqueous solution (pH 14.00) shown in Example 1 to obtain a transparent liquid having pH 14. Next, to this mixed solution, niobium oxalate aqueous solution (pH 1.20) and KOH aqueous solution (pH 14.00) were alternately added and mixed at the addition amounts shown in Table 3, and finally mixed at pH 7.85. A liquid (precipitate solution) was obtained. In this case, niobium oxalate solution and K
The addition of the OH aqueous solution was promptly performed. After addition, each pH was maintained for 3 minutes. Table 3 also shows the pH of the mixed solution after addition of the niobium oxalate aqueous solution and the KOH aqueous solution.
【００２９】[0029]
【表３】 [Table 3]
【００３０】次に、前記のようにして得たｐＨ７．８５
の混合液を実施例１の場合と同様に後処理して、ニオブ
酸粒子及びその脱水物を得た。このように得られたニオ
ブ酸粒子は平均粒径３．０μｍでかつ１μｍ以下の微粒
子を全く含まないものであった。この脱水物の性状を表
４に示す。Next, the pH obtained as described above is 7.85.
The mixed solution of (1) was post-treated in the same manner as in Example 1 to obtain niobate particles and its dehydrated product. The niobate particles thus obtained had an average particle size of 3.0 μm and contained no fine particles of 1 μm or less. Table 4 shows the properties of this dehydrated product.
【００３１】[0031]
【表４】 [Table 4]
【００３２】比較例１ 実施例１で示したシュウ酸ニオブ水溶液５リットルに対
し、撹拌下、実施例１で示したＫＯＨ水溶液１．３５リ
ットルを混合液の平均ｐＨ上昇速度が０．２／分で徐々
に添加混合した。得られた混合液を実施例１と同様にし
て後処理し、ニオブ粒子の脱水物を得た。このものの耐
水熱性試験前後の酸量Ａ及び酸量Ａ減少率を測定した結
果、その試験前の酸量Ａは０．３０ｍｍｏｌ／ｇ、試験
後の酸量Ａは０．２４ｍｍｏｌ／ｇであり、酸量Ａ減少
率は２０％であった。Comparative Example 1 With respect to 5 liters of the niobium oxalate aqueous solution shown in Example 1, 1.35 liters of the KOH aqueous solution shown in Example 1 was stirred with an average pH increase rate of 0.2 / min. Was gradually added and mixed. The obtained mixed liquid was post-treated in the same manner as in Example 1 to obtain a dehydrated product of niobium particles. As a result of measuring the acid amount A and the acid amount A reduction rate before and after the hydrothermal resistance test of this product, the acid amount A before the test was 0.30 mmol / g, and the acid amount A after the test was 0.24 mmol / g, The acid amount A reduction rate was 20%.
【図１】ｐＨ変動法によりニオブ酸粒子を製造する方法
のフローシートの一例を示す。FIG. 1 shows an example of a flow sheet of a method for producing niobate particles by a pH fluctuation method.
１，２ 容器 ３，４ 混合器 ５，６ ポンプ 1, 2 containers 3, 4 mixers 5, 6 pumps
Claims (6)
に、酸度関数Ｈｏ：−３．０以下の酸量Ａを０．３５ｍ
ｍｏｌ／ｇ以上有し、その酸量Ａのうちの５０％以上が
Ｈｏ：−５．６以下の強酸量であり、かつ３５０℃の耐
水熱性試験後の酸量Ａ減少率が１０％以下であるニオブ
酸粒子。1. An acid amount A having an average particle size of 1 μm or more and an acidity function Ho: −3.0 or less is 0.35 m.
mol / g or more, 50% or more of the acid amount A thereof is a strong acid amount of Ho: -5.6 or less, and the acid amount A decrease rate after the hydrothermal resistance test at 350 ° C. is 10% or less. Some niobate particles.
ていない１１より大きいｐＨのアルカリ性水溶液に、ニ
オブ化合物を溶解したｐＨ５以下の酸性水溶液を撹拌下
で混合液の平均ｐＨ降下率が０．２／分以下になるよう
に徐々に添加混合して、平均粒径が１μｍ以上のニオブ
酸粒子を含むｐＨ５．５〜１１．０の混合液を得ること
を特徴とするニオブ酸粒子の製造方法。2. An average pH drop rate of a mixed solution of an alkaline aqueous solution having a pH of more than 11 in which a niobium compound is dissolved or not dissolved is 0.1. A method for producing niobate particles, characterized in that a mixed solution having a pH value of 5.5 to 11.0 containing niobate particles having an average particle size of 1 μm or more is obtained by gradually adding and mixing so as to be 2 / min or less. .
含むｐＨ５．５〜１１．０の混合液に対し、ｐＨ５以下
の酸性水溶液を添加混合する工程と、１１より大きいｐ
Ｈのアルカリ性水溶液を添加混合する工程をその混合液
のｐＨを５．５〜１１．０の範囲に保持しながら交互に
繰返し行い、平均粒径が１μｍ以上のニオブ酸粒子を含
む混合液を得ることを特徴とするニオブ酸粒子の製造方
法。3. A step of adding and mixing an acidic aqueous solution having a pH of 5 or less to a mixed solution having a pH of 5.5 to 11.0 and containing niobate particles having an average particle diameter of 1 μm or more, and a p value larger than 11
The step of adding and mixing the alkaline aqueous solution of H is alternately repeated while maintaining the pH of the mixed solution in the range of 5.5 to 11.0 to obtain a mixed solution containing niobate particles having an average particle diameter of 1 μm or more. A method for producing niobate particles, comprising:
性水溶液の少なくとも一方にニオブ化合物を溶解させる
請求項３の方法。4. The method according to claim 3, wherein the niobium compound is dissolved in at least one of an acidic aqueous solution and an alkaline aqueous solution added to the mixed solution.
含むｐＨ５．５〜１１．０の混合液に対し、ｐＨ５以下
の酸性水溶液を添加混合する工程と、１１より大きいｐ
Ｈのアルカリ性水溶液を添加混合する工程を、その混合
液のｐＨを５．５〜１１．０の範囲に保持しながら交互
に繰返し行い、その際、前記アルカリ性水溶液及び酸性
水溶液の少なくとも一方にニオブ化合物を溶解させて、
平均粒径が１μｍ以上のニオブ酸粒子を含むｐＨ５．５
〜１１．０の混合液を得ることを特徴とするニオブ酸粒
子の製造方法。5. A step of adding and mixing an acidic aqueous solution having a pH of 5 or less to a mixed solution having a pH of 5.5 to 11.0 and containing niobate particles having an average particle size of less than 1 μm, and a p value larger than 11
The step of adding and mixing the alkaline aqueous solution of H is alternately repeated while maintaining the pH of the mixed solution in the range of 5.5 to 11.0, in which case at least one of the alkaline aqueous solution and the acidic aqueous solution contains a niobium compound. Dissolve
PH 5.5 including niobate particles having an average particle diameter of 1 μm or more
A method for producing niobate particles, which comprises obtaining a mixed solution of 11.0.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5225230A JPH0753219A (en) | 1993-08-18 | 1993-08-18 | Niobic acid particle and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5225230A JPH0753219A (en) | 1993-08-18 | 1993-08-18 | Niobic acid particle and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0753219A true JPH0753219A (en) | 1995-02-28 |
Family
ID=16826033
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5225230A Pending JPH0753219A (en) | 1993-08-18 | 1993-08-18 | Niobic acid particle and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0753219A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100413580C (en) * | 2004-09-24 | 2008-08-27 | 中国石油化工股份有限公司 | Method for preparing catalyst for hydration of epoxy ethane to prepare ethandiol |
| US7925391B2 (en) * | 2005-06-02 | 2011-04-12 | The Boeing Company | Systems and methods for remote display of an enhanced image |
-
1993
- 1993-08-18 JP JP5225230A patent/JPH0753219A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100413580C (en) * | 2004-09-24 | 2008-08-27 | 中国石油化工股份有限公司 | Method for preparing catalyst for hydration of epoxy ethane to prepare ethandiol |
| US7925391B2 (en) * | 2005-06-02 | 2011-04-12 | The Boeing Company | Systems and methods for remote display of an enhanced image |
| US8874284B2 (en) | 2005-06-02 | 2014-10-28 | The Boeing Company | Methods for remote display of an enhanced image |
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