JP5750662B2 - Cerium oxide nanoparticle-zeolite composite, its production method and use as ultraviolet shielding material - Google Patents
Cerium oxide nanoparticle-zeolite composite, its production method and use as ultraviolet shielding material Download PDFInfo
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- 229910000420 cerium oxide Inorganic materials 0.000 title claims description 120
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 title claims description 119
- 229910021536 Zeolite Inorganic materials 0.000 title claims description 109
- 239000010457 zeolite Substances 0.000 title claims description 109
- 239000002131 composite material Substances 0.000 title claims description 48
- 238000004519 manufacturing process Methods 0.000 title claims description 21
- 239000000463 material Substances 0.000 title claims description 13
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 87
- 238000005342 ion exchange Methods 0.000 claims description 68
- 239000002105 nanoparticle Substances 0.000 claims description 58
- 239000002245 particle Substances 0.000 claims description 57
- 229910044991 metal oxide Inorganic materials 0.000 claims description 45
- 150000004706 metal oxides Chemical class 0.000 claims description 45
- 239000006104 solid solution Substances 0.000 claims description 35
- 239000013078 crystal Substances 0.000 claims description 33
- 150000002500 ions Chemical class 0.000 claims description 23
- 229910052751 metal Inorganic materials 0.000 claims description 20
- 239000002184 metal Substances 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 17
- 150000003839 salts Chemical class 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 9
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 7
- 150000002739 metals Chemical class 0.000 claims description 7
- 239000002253 acid Substances 0.000 claims description 6
- 229910052779 Neodymium Inorganic materials 0.000 claims description 5
- 229910052772 Samarium Inorganic materials 0.000 claims description 5
- 230000001590 oxidative effect Effects 0.000 claims description 5
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 4
- 239000003513 alkali Substances 0.000 claims description 4
- 239000002537 cosmetic Substances 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 4
- 239000004033 plastic Substances 0.000 claims description 4
- 229920003023 plastic Polymers 0.000 claims description 4
- 230000006866 deterioration Effects 0.000 claims description 3
- 239000003973 paint Substances 0.000 claims description 3
- 238000010304 firing Methods 0.000 claims description 2
- 230000003647 oxidation Effects 0.000 claims description 2
- 238000007254 oxidation reaction Methods 0.000 claims description 2
- 239000002585 base Substances 0.000 claims 1
- 238000004898 kneading Methods 0.000 claims 1
- 238000000465 moulding Methods 0.000 claims 1
- 230000007935 neutral effect Effects 0.000 claims 1
- 239000007787 solid Substances 0.000 claims 1
- 230000000475 sunscreen effect Effects 0.000 claims 1
- 239000000516 sunscreening agent Substances 0.000 claims 1
- 238000000034 method Methods 0.000 description 21
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 17
- 239000010419 fine particle Substances 0.000 description 17
- 229910052684 Cerium Inorganic materials 0.000 description 15
- 238000002441 X-ray diffraction Methods 0.000 description 10
- 239000000126 substance Substances 0.000 description 9
- -1 cerium ions Chemical class 0.000 description 8
- 239000000377 silicon dioxide Substances 0.000 description 8
- 239000003054 catalyst Substances 0.000 description 7
- 239000000243 solution Substances 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 7
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 230000003197 catalytic effect Effects 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 238000001354 calcination Methods 0.000 description 4
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 4
- 229910021645 metal ion Inorganic materials 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001027 hydrothermal synthesis Methods 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- XQTIWNLDFPPCIU-UHFFFAOYSA-N cerium(3+) Chemical compound [Ce+3] XQTIWNLDFPPCIU-UHFFFAOYSA-N 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011246 composite particle Substances 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 150000002484 inorganic compounds Chemical class 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 229910001414 potassium ion Inorganic materials 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 238000012552 review Methods 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910001415 sodium ion Inorganic materials 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 150000000703 Cerium Chemical class 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 229910052693 Europium Inorganic materials 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 229910052771 Terbium Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- JYIBXUUINYLWLR-UHFFFAOYSA-N aluminum;calcium;potassium;silicon;sodium;trihydrate Chemical compound O.O.O.[Na].[Al].[Si].[K].[Ca] JYIBXUUINYLWLR-UHFFFAOYSA-N 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 150000001785 cerium compounds Chemical class 0.000 description 1
- DRVWBEJJZZTIGJ-UHFFFAOYSA-N cerium(3+);oxygen(2-) Chemical class [O-2].[O-2].[O-2].[Ce+3].[Ce+3] DRVWBEJJZZTIGJ-UHFFFAOYSA-N 0.000 description 1
- ITZXULOAYIAYNU-UHFFFAOYSA-N cerium(4+) Chemical compound [Ce+4] ITZXULOAYIAYNU-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
- UNJPQTDTZAKTFK-UHFFFAOYSA-K cerium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Ce+3] UNJPQTDTZAKTFK-UHFFFAOYSA-K 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910001902 chlorine oxide Inorganic materials 0.000 description 1
- 229910001603 clinoptilolite Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 150000004696 coordination complex Chemical class 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000003925 fat Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002159 nanocrystal Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 1
- 238000009931 pascalization Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000001699 photocatalysis Effects 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000000634 powder X-ray diffraction Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 238000004876 x-ray fluorescence Methods 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
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- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Cosmetics (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
Description
本発明は、ゼオライト結晶構造内に酸化セリウムのナノ粒子が分散した状態で存在する、酸化セリウムナノ粒子−ゼオライト複合体と、その製造方法とに関する。この複合体としては、とりわけ、ゼオライトとして板状の結晶形態をもつものを使用して得られる、酸化セリウムナノ粒子−板状ゼオライト複合体が重要である。 The present invention relates to a cerium oxide nanoparticle-zeolite composite in which cerium oxide nanoparticles are dispersed in a zeolite crystal structure, and a method for producing the same. Of particular importance as this composite is a cerium oxide nanoparticle-plate-like zeolite composite obtained by using a zeolite having a plate-like crystal form.
本発明はまた、酸化セリウムにセリウム以外の金属の酸化物を固溶体として共存させた金属酸化物固溶酸化セリウムが、ゼオライト結晶構造内にナノ粒子の形で分散した状態で存在する、ナノ粒子−ゼオライト複合体と、その製造方法にも関する。 The present invention also relates to a nanoparticle in which metal oxide solid solution cerium oxide in which a metal oxide other than cerium coexists in cerium oxide as a solid solution is present in the form of nanoparticles dispersed in a zeolite crystal structure. The present invention also relates to a zeolite composite and a method for producing the same.
本発明はさらに、上記の酸化セリウムナノ粒子−板状ゼオライト複合体または金属酸化物固溶酸化セリウムナノ粒子−板状ゼオライト複合体から分離取得した、ナノメータレベルの微細で均一な粒径分布を有する、酸化セリウムナノ粒子または金属酸化物固溶酸化セリウムナノ粒子それ自体と、その製造方法とに関する。 The present invention further provides an oxide having a fine and uniform particle size distribution at a nanometer level obtained separately from the cerium oxide nanoparticle-plate-like zeolite composite or the metal oxide solid solution cerium oxide nanoparticle-plate-like zeolite composite. The present invention relates to a cerium nanoparticle or a metal oxide solid solution cerium oxide nanoparticle itself and a production method thereof.
酸化セリウムの特性の向上、とくに触媒特性の向上を目的とした、ナノ粒子化技術が開発されている。従来の酸化セリウムの製造方法は、セリウム塩の水溶液に塩素および水酸化ナトリウムを加えて水酸化セリウムの沈殿を生成させ、それを焼成、粉砕することによって行われてきたが、その方法では、粒子の形態および粒径を制御することができなかった。ナノ粒子化技術として提案された方法のひとつは、有機溶媒の存在下で酸化セリウム前駆体を製造し、水熱反応により約３０〜３００ｎｍの粒径を有する酸化セリウムナノ粒子を製造する方法（特許文献１）である。この技術で得られる酸化セリウムは粒径の分布が広いから、均一な粒径の酸化セリウムを得ることはできない。いまひとつの技術は、有機溶媒中での合成反応により、平均粒径が１００ｎｍ以下の酸化セリウムナノ粒子を製造する方法（特許文献２）であるが、この技術も、酸化セリウムの粒度分布が広く、均一な粒径の製品を提供することはできない。 Nanoparticulation technology has been developed for the purpose of improving the properties of cerium oxide, especially the catalytic properties. A conventional method for producing cerium oxide has been carried out by adding chlorine and sodium hydroxide to an aqueous solution of cerium salt to form a precipitate of cerium hydroxide, which is calcined and pulverized. It was not possible to control the morphology and particle size of One of the methods proposed as a nanoparticulate technique is a method of producing a cerium oxide precursor in the presence of an organic solvent and producing cerium oxide nanoparticles having a particle size of about 30 to 300 nm by a hydrothermal reaction (Patent Literature). 1). Since cerium oxide obtained by this technique has a wide particle size distribution, it is not possible to obtain cerium oxide having a uniform particle size. Another technique is a method for producing cerium oxide nanoparticles having an average particle diameter of 100 nm or less by a synthesis reaction in an organic solvent (Patent Document 2). This technique also has a wide cerium oxide particle size distribution and is uniform. It is not possible to provide a product with a small particle size.
酸化セリウムに限らず、金属酸化物から１〜２００ｎｍの範囲内の粒度を有する微粒子を製造する方法として、機械的な微粉砕処理を工程に含む技術が開発された（特許文献３）。しかし機械的な処理は、原理的に考えても均一な粒径の金属酸化物粉末を与えない。これと異なる技術として、金属酸化物固溶体の製造を、反応混合物を加圧下に連続的に反応させることにより行なうことが考案された（特許文献４）。高圧装置を必要とするうえ、高圧処理のため作業性が悪いという不利がある。 As a method for producing fine particles having a particle size within a range of 1 to 200 nm from metal oxides, not limited to cerium oxide, a technique including mechanical pulverization treatment in the process has been developed (Patent Document 3). However, mechanical treatment does not give a metal oxide powder with a uniform particle size even in principle. As a technique different from this, it has been devised to produce a metal oxide solid solution by continuously reacting a reaction mixture under pressure (Patent Document 4). In addition to requiring a high-pressure device, there is a disadvantage that workability is poor due to high-pressure processing.
均一な粒径をもった酸化セリウムのナノ結晶を製造することが可能な技術として、無水性の、および有水性の、ゾル・ゲル反応を行なう方法が提案された（特許文献５）。ただしこの方法は、有機溶媒を使用し、操作が煩雑である。やはり狭い粒度分布をもった金属酸化物ナノ粒子を合成する方法として、金属塩または金属錯体を含む溶液に、紫外線領域波長レーザーを照射する方法も提案された（特許文献６）。これも、合成に特殊な装置を必要とする。 As a technique capable of producing cerium oxide nanocrystals having a uniform particle size, an anhydrous and hydrous sol-gel reaction method has been proposed (Patent Document 5). However, this method uses an organic solvent and is complicated in operation. As a method for synthesizing metal oxide nanoparticles having a narrow particle size distribution, a method of irradiating a solution containing a metal salt or metal complex with an ultraviolet region wavelength laser has also been proposed (Patent Document 6). This also requires special equipment for synthesis.
一方、ゼオライトは、そのキャビティ（細孔）内に種々の金属元素をイオン交換により均一に分散させることが容易であることから、ゼオライトを母結晶ないし原料に用いたイオン交換体が、蛍光体の製造をはじめとして、さまざまな分野で試作されている。ゼオライトをセリウムイオンで交換したものは、とくに触媒として有用であって、たとえば、β型ゼオライトをセリウムイオンでイオン交換したものを、排気ガス浄化用触媒として使用するという提案がある（特許文献７）。ただし、これは酸化セリウムを合成する技術ではない。排気ガス浄化用触媒に関しては、ゼオライトをセリウムイオンでイオン交換するとともに、酸化セリウムに担持される化合物を含有する触媒を製造する技術がある（特許文献８）が、ゼオライトの構造内に酸化セリウムのナノ粒子を合成するものではない。 On the other hand, since zeolite can easily disperse various metal elements uniformly in its cavity (pore) by ion exchange, an ion exchanger using zeolite as a mother crystal or raw material is a phosphor. It has been prototyped in various fields including manufacturing. The one obtained by exchanging zeolite with cerium ions is particularly useful as a catalyst. For example, there is a proposal to use β-type zeolite ion exchanged with cerium ions as an exhaust gas purifying catalyst (Patent Document 7). . However, this is not a technique for synthesizing cerium oxide. As for the exhaust gas purifying catalyst, there is a technology for producing a catalyst containing a compound supported on cerium oxide while performing ion exchange of zeolite with cerium ions (Patent Document 8). It does not synthesize nanoparticles.
近年、オゾン層の破壊の問題を契機として、人体に対する紫外線の有害さが懸念されている。樹脂や塗料も、日光に暴露されると紫外線の影響を受け、経時的に劣化し、変色したり亀裂が生じたりするという問題がある。そこで、こうした害を防ぐ対策の一つとして、種々の有機系や無機系の紫外線遮蔽材が開発されつつある。酸化セリウムの微粒子は、二酸化チタン、酸化亜鉛、酸化鉄のような金属酸化物の微粒子とともに、紫外線遮蔽効果の大きい物質として知られ、無機系紫外線遮蔽材として有力な物質である。 In recent years, there has been concern about the harmfulness of ultraviolet rays on the human body triggered by the problem of ozone layer destruction. Resins and paints are also affected by ultraviolet rays when exposed to sunlight, and there is a problem that they deteriorate over time, causing discoloration or cracks. Therefore, various organic and inorganic ultraviolet shielding materials are being developed as a measure for preventing such damage. The fine particles of cerium oxide, together with fine particles of metal oxides such as titanium dioxide, zinc oxide, and iron oxide, are known as substances having a large ultraviolet shielding effect, and are effective substances as inorganic ultraviolet shielding materials.
ところが一方で、酸化セリウムをはじめとする金属酸化物の微粒子は、光触媒作用あるいは熱触媒作用を有しており、単に化粧品や塗料の材料、プラスチックなどに配合した場合、その中の有機物質成分を劣化させ、変質させる可能性があるという問題がある。また、紫外線の遮蔽効率を向上させるには、粒子をできるだけ小さくすることが望ましいが、一般的にこれら金属酸化物の微粒子はきわめて凝集しやすく、それを添加すべき物質中に均一に分散させることは困難であり、そのために、本来もっている紫外線遮蔽効果が十分に発揮できないという悩みもあった。 On the other hand, fine particles of metal oxides such as cerium oxide have photocatalytic or thermal catalytic action, and when they are simply blended into cosmetics, paint materials, plastics, etc., the organic substance components in them are contained. There is a problem that there is a possibility of deterioration and alteration. In order to improve the shielding efficiency of ultraviolet rays, it is desirable to make the particles as small as possible. In general, however, these metal oxide fine particles are very likely to aggregate and should be uniformly dispersed in the substance to be added. For this reason, there was a problem that the inherent ultraviolet shielding effect could not be fully exhibited.
そこで、こうした問題を解決する手段として、金属酸化物の微粒子を、触媒活性のない無機化合物で被覆することや、形態を制御することが試みられてきた。その一例は、紫外線遮蔽機能を有する金属または金属酸化物を、シリカによって内包した複合化粒子の提案である（特許文献９）。この複合化粒子は、一次粒子が鱗片板状の形状であることを特徴としているが、水熱合成によって製造したものであり、金属または金属酸化物の分散状態は明らかでない。 Therefore, as means for solving such problems, attempts have been made to coat metal oxide fine particles with an inorganic compound having no catalytic activity and to control the form. One example is a proposal of composite particles in which a metal or metal oxide having an ultraviolet shielding function is encapsulated with silica (Patent Document 9). The composite particles are characterized in that the primary particles have a scale-plate shape, but are produced by hydrothermal synthesis, and the dispersion state of the metal or metal oxide is not clear.
シリカで被覆した金属酸化物粒子に関しては、ゾル−ゲル反応を応用して変性シリカ被覆粒子を製造する方法がある（特許文献１０）。ところが、被覆粉体を粉砕する過程を必要とするため、形態および粒径を制御するという観点からは、有力でない。水熱合成により酸化セリウム微粒子、セリウム含有複合酸化物微粒子を、不定形または結晶性の無機化合物で被覆した紫外線遮蔽材が考えられた（特許文献１１）が、水熱合成は粒子の形態および粒径を制御するには適しない。 Regarding metal oxide particles coated with silica, there is a method of producing modified silica-coated particles by applying a sol-gel reaction (Patent Document 10). However, since a process of pulverizing the coated powder is required, it is not effective from the viewpoint of controlling the form and particle size. An ultraviolet shielding material in which cerium oxide fine particles and cerium-containing composite oxide fine particles are coated with an amorphous or crystalline inorganic compound by hydrothermal synthesis has been considered (Patent Document 11). It is not suitable for controlling the diameter.
金属酸化物微粒子をシリカで被覆することは引き続き試みられており、シリカからなる粒径が２０〜１００nmの粒子の内部に、１個または複数個の酸化セリウムまたは酸化チタンを含有させた構造を有する微粒子が提案された（特許文献１２）。この技術は、粒子の形態や粒径の制御には及んでない。膜厚が０．１〜１００nmであるシリカで金属酸化物粉末を被覆したものを、シリカ被膜形成用組成物に金属酸化物粉を接触させて表面にシリカを選択的に沈着させる、という手法で製造することも行われた（特許文献１３）。しかしながらこの技術でも、製品のシリカ被膜金属酸化物の形態や粒径を、はっきり制御することはできない。 It has been continuously attempted to coat metal oxide fine particles with silica, and has a structure in which one or a plurality of cerium oxides or titanium oxides are contained in particles having a particle diameter of 20 to 100 nm made of silica. Fine particles have been proposed (Patent Document 12). This technique does not extend to the control of particle morphology and particle size. In a technique in which a metal oxide powder is coated with silica having a film thickness of 0.1 to 100 nm, the silica is selectively deposited on the surface by bringing the metal oxide powder into contact with the composition for forming a silica film. It was also manufactured (Patent Document 13). However, even with this technique, the form and particle size of the silica-coated metal oxide of the product cannot be clearly controlled.
セリウム化合物、とりわけセリアすなわち酸化セリウムのさまざまな分野における広範な用途については、最近の総説（非特許文献１）にまとめられている。
本発明の目的は、第一に、ナノレベルの微細な粒径を有し、しかも粒径が均一な酸化セリウムのナノ粒子がゼオライト中に分散した形で存在する、酸化セリウムナノ粒子−ゼオライト複合体を提供することにある。この複合体を製造する方法を提供することも、本発明の目的に含まれる。 The object of the present invention is, firstly, a cerium oxide nanoparticle-zeolite composite having nano-scale fine particle diameters and having cerium oxide nanoparticles having a uniform particle diameter dispersed in zeolite. Is to provide. Providing a method for producing this complex is also included in the object of the present invention.
本発明の目的は、第二に、ナノレベルの微細な粒径を有し、しかも粒径が均一な酸化セリウムのナノ粒子が、Ｃｅ以外の金属、すなわち、Ｃａ，Ｐｒ，Ｎｄ，ＳｍまたはＧｄの酸化物を固溶体として取り込んだ粒子としてゼオライト中に分散した形で存在する、金属酸化物固溶酸化セリウムナノ粒子−ゼオライト複合体を提供することにある。この複合体を製造する方法を提供することも、本発明の目的に含まれる。 Secondly, the object of the present invention is that nano-level cerium oxide nanoparticles having a fine particle size and uniform particle size are made of a metal other than Ce, that is, Ca, Pr, Nd, Sm or Gd. It is an object of the present invention to provide a metal oxide solid solution cerium oxide nanoparticle-zeolite composite which exists in a form dispersed in zeolite as particles in which the oxide is incorporated as a solid solution. Providing a method for producing this complex is also included in the object of the present invention.
本発明の目的は、第三に、上記した酸化セリウムナノ粒子−ゼオライト複合体または金属酸化物固溶酸化セリウムナノ粒子−ゼオライト複合体から分離取得した、ナノレベルの微細な粒径を有し、しかも粒径が均一な、酸化セリウムナノ粒子または金属酸化物固溶酸化セリウムナノ粒子を提供することにある。これらのナノ粒子を製造する方法を提供することも、本発明の目的に含まれる。 Thirdly, the object of the present invention is to obtain a nano-sized fine particle diameter separated from the cerium oxide nanoparticle-zeolite composite or metal oxide solid solution cerium oxide nanoparticle-zeolite composite described above, The object is to provide cerium oxide nanoparticles or metal oxide solid solution cerium oxide nanoparticles having a uniform diameter. Providing a method for producing these nanoparticles is also included in the object of the present invention.
本発明の応用面における目的は、上記した形態の酸化セリウムナノ粒子−ゼオライト複合体もしくは金属酸化物固溶酸化セリウムナノ粒子−ゼオライト複合体を提供することによって、または、酸化セリウムナノ粒子もしくは金属酸化物固溶酸化セリウムナノ粒子を提供することによって、一般に凝集性が強いというナノ粒子に共通の取り扱いにくさを解決し、紫外線遮蔽材としてのすぐれた性能を十分に発揮させるとともに、表面被覆により触媒活性を抑制した物質を提供することにある。 The purpose of the application of the present invention is to provide a cerium oxide nanoparticle-zeolite composite or metal oxide solid solution cerium oxide nanoparticle-zeolite composite of the above-described form, or cerium oxide nanoparticle or metal oxide solid solution. By providing cerium oxide nanoparticles, it is difficult to handle the common handling of nanoparticles, which are generally strong in cohesion, and they exhibit excellent performance as an ultraviolet shielding material, while suppressing the catalytic activity by surface coating. To provide a substance.
本発明の、酸化セリウムのナノ粒子がゼオライト中に分散した形で混在する酸化セリウムナノ粒子−ゼオライト複合体は、Ｋ 2 Ｏ・Ａｌ 2 Ｏ 3 ・２ＳｉＯ 2 ・ｘＨ 2 Ｏの組成を有し六角板状の結晶形態をもつ「リンデＱ」型ゼオライト中に、Ｋ 2 Ｏ・Ａｌ 2 Ｏ 3 ・２ＳｉＯ 2 ・ｘＨ 2 Ｏの組成を有し六角板状の結晶形態をもつ「リンデＱ」型ゼオライト中に、
粒径１〜２０ｎｍの酸化セリウムＣｅＯ２ナノ粒子が分散した形で存在する複合体である。複合体のゼオライトは、本来の結晶構造を維持しているものであってもよいし、たとえば加熱されて結晶構造が崩壊したものであってもよいし、その中間の、ミクロ構造は破壊されたものの、外見上の結晶形態は維持されている、という段階のものであってもよい。
Of the present invention, cerium oxide particles cerium oxide nanoparticles are mixed with dispersed form in the zeolite - zeolite complex, a hexagonal plate having a composition of K 2 O · Al 2 O 3 · 2SiO 2 · xH 2 O with Jo crystalline form in "Linde Q" type zeolite, K 2 O · Al 2 O 3 · 2SiO 2 · xH 2 O "Linde Q" with hexagonal plate-like crystal form having a composition of zeolite in In addition,
This is a composite in which cerium oxide CeO 2 nanoparticles having a particle diameter of 1 to 20 nm are dispersed. The composite zeolite may be the one that maintains the original crystal structure, or may be one that has been destroyed by heating, for example, or the intermediate microstructure has been destroyed. However, it may be in a stage where the apparent crystal form is maintained.
本発明の、酸化セリウムのナノ粒子がＣｅ以外の金属の酸化物を固溶体として取り込んだ粒子としてゼオライト中に分散した形で存在する金属酸化物固溶酸化セリウムナノ粒子−ゼオライト複合体は、同じくＫ2Ｏ・Ａｌ2Ｏ3・２ＳｉＯ2・ｘＨ2Ｏの組成を有し六角板状の結晶形態をもつ「リンデＱ」型ゼオライト中に、粒径１〜２０ｎｍの酸化セリウムＣｅＯ２ナノ粒子が、Ｃａ，Ｐｒ，Ｎｄ，ＳｍまたはＧｄの酸化物を固溶体として取り込んだ粒子としてゼオライト中に分散した形で存在する複合体である。この場合も、上記と同様に複合体のゼオライトは、本来の結晶構造を維持しているものであってもよいし、たとえば加熱されて結晶構造が崩壊したものであってもよいし、その中間の段階のものであってもよい。
The metal oxide solid solution cerium oxide nanoparticle-zeolite complex, which is present in the form in which the cerium oxide nanoparticles of the present invention are dispersed in zeolite as a solid solution of a metal oxide other than Ce, is also K 2. O · Al 2 O 3 · 2SiO with hexagonal plate-like crystal form having a composition of 2 · xH 2 O in "Linde Q" type zeolite bets, cerium oxide CeO 2 nanoparticles having a particle size of 1 to 20 nm, It is a composite that exists in a form dispersed in zeolite as particles in which an oxide of Ca, Pr, Nd, Sm, or Gd is incorporated as a solid solution. Also in this case, the composite zeolite may maintain the original crystal structure, as described above, or may be, for example, a material whose crystal structure has been destroyed by heating, It may be of the stage.
本発明の、粒径１〜２０ｎｍの酸化セリウムのナノ粒子がゼオライト中に分散した形で存在する酸化セリウムナノ粒子−ゼオライト複合体を製造する方法は、Ｃｅの可溶性塩の水溶液にゼオライトを浸漬し、１００℃以下の温度でゼオライト中のＫ＋とＣｅ３＋イオンとのイオン交換を行なって、少なくとも１０％の交換率でＣｅイオンを存在させたのち、酸化性の雰囲気下に、８００℃以上１０００℃未満の温度で焼成することにより、酸化セリウムＣｅＯ２ナノ粒子を形成させることからなる。
Of the present invention, cerium oxide particles cerium oxide nanoparticles having a particle size 1~20nm are present in dispersed form in the zeolite - process for producing a zeolite composite, immersing the zeolite in an aqueous solution of a soluble salt of Ce, After performing ion exchange between K + and Ce 3+ ions in the zeolite at a temperature of 100 ° C. or lower to make Ce ions exist at an exchange rate of at least 10%, 800 ° C. or higher and 1000 ° C. in an oxidizing atmosphere. It comprises forming cerium oxide CeO 2 nanoparticles by firing at a temperature below .
本発明の、粒径１〜２０ｎｍの酸化セリウムのナノ粒子がＣｅ以外の金属の酸化物を固溶体として取り込んだ粒子としてゼオライト中に分散した形で存在する金属酸化物固溶酸化セリウムナノ粒子−ゼオライト複合体を製造する方法は、Ｃｅの可溶性塩と、Ｃｅ以外の金属すなわちＣａ，Ｐｒ，Ｎｄ，ＳｍおよびＧｄの可溶性塩から選んだ少なくとも１種の塩とを混合して含有する水溶液にゼオライトを浸漬し、１００℃以下の温度でゼオライト中のＫ＋とＣｅ３＋イオンおよびＣｅ以外の金属のイオンとのイオン交換を行なって、少なくとも１０％の交換率でＣｅイオンおよびＣｅ以外の金属のイオンを存在させたのち、酸化性の雰囲気下に、８００℃以上１０００℃未満の温度で焼成することにより、Ｃｅ以外の金属の酸化物を固溶体として取り込んだ酸化セリウムＣｅＯ２ナノ粒子を形成させることからなる。
Metal oxide solid solution cerium oxide nanoparticle-zeolite composite in which cerium oxide nanoparticles having a particle diameter of 1 to 20 nm of the present invention are present in a form dispersed in zeolite as particles incorporating a metal oxide other than Ce as a solid solution A method for producing a body includes immersing zeolite in an aqueous solution containing a mixture of a soluble salt of Ce and at least one salt selected from metals other than Ce, ie, soluble salts of Ca, Pr, Nd, Sm and Gd. Then, ion exchange between K + and Ce 3+ ions and ions of metals other than Ce in zeolite is performed at a temperature of 100 ° C. or less, and Ce ions and ions of metals other than Ce are present at an exchange rate of at least 10%. After is, a solid solution under an oxidizing atmosphere and calcined at temperatures below 800 ° C. or higher 1000 ° C., the oxide of a metal other than Ce To consists in forming a cerium oxide CeO 2 nanoparticles captured.
本発明の、粒径１〜２０ｎｍの微細な粒径を有し、しかも粒径が均一な酸化セリウムナノ粒子を製造する方法は、上記の酸化セリウムナノ粒子−ゼオライト複合体に対して酸またはアルカリを作用させてゼオライトを溶解し、溶解せずに残った酸化セリウムナノ粒子を濾過により分離取得することからなる。本発明の、粒径１〜２０ｎｍの微細な粒径を有し、しかも粒径が均一な金属酸化物固溶酸化セリウムナノ粒子を製造する方法は、これと同様に、上記の金属酸化物固溶酸化セリウムナノ粒子−ゼオライト複合体に対して酸またはアルカリを作用させてゼオライトを溶解し、溶解せずに残った金属酸化物固溶酸化セリウムナノ粒子を濾過により分離取得することからなる。
The method for producing a cerium oxide nanoparticle having a fine particle diameter of 1 to 20 nm and having a uniform particle diameter according to the present invention acts by applying an acid or an alkali to the cerium oxide nanoparticle-zeolite composite. Then, the zeolite is dissolved, and the cerium oxide nanoparticles remaining without being dissolved are separated and obtained by filtration. Of the present invention have a fine particle size having a particle size of 1 to 20 nm, yet how the particle size to produce a uniform metal oxide solid solution cerium oxide nanoparticles, like this, the metal oxide solid solution It consists of dissolving the zeolite by allowing acid or alkali to act on the cerium oxide nanoparticle-zeolite complex, and separating and obtaining the metal oxide solid solution cerium oxide nanoparticles remaining without being dissolved.
本発明の酸化セリウムナノ粒子は、ゼオライトに、そのＫ＋またはＮａ＋イオンとセリウムイオンＣｅ３＋とのイオン交換により与えたセリウム（III）が、酸化性雰囲気下での焼成によりセリウム（IV）の酸化物となるという機構により、形成されたものである。一般に、金属イオンでイオン交換したゼオライトを加熱すると、ゼオライト構造が分解した後、通常はアルミノケイ酸金属塩やアルミン酸金属塩が生成し、イオン交換された金属の酸化物が生成することはない。本発明は、これまで当業者がもっていた知見からは予想できなかった新規な経路により、はじめて酸化セリウムナノ粒子を実現したものである。ゼオライトとセリウムイオンＣｅ３＋とのイオン交換も、その焼成も簡単な操作であって、格別の装置も操作も必要なく、本発明は低コストで容易に実施することができる。 In the cerium oxide nanoparticles of the present invention, cerium (III) given to zeolite by ion exchange between K + or Na + ions and cerium ions Ce 3+ oxidizes cerium (IV) by calcination in an oxidizing atmosphere. It is formed by the mechanism of becoming an object. In general, when a zeolite ion-exchanged with metal ions is heated, after the zeolite structure is decomposed, usually an aluminosilicate metal salt or an aluminate metal salt is produced, and an ion-exchanged metal oxide is not produced. The present invention realizes cerium oxide nanoparticles for the first time by a novel route that could not be predicted from the knowledge that those skilled in the art had so far. The ion exchange between the zeolite and the cerium ion Ce 3+ and the calcination thereof are simple operations, and no special apparatus or operation is required, and the present invention can be easily implemented at low cost.
これまでに知られている酸化セリウムの微粒子は、その粒径の制御が困難であるばかりか、微粒子にすると凝集しやすく、分散性が不十分なものしか得られなかった。本発明によって、ゼオライト中に良好な分散状態で混在する酸化セリウムナノ粒子が得られ、所望であれば、ゼオライトの結晶形態や粒径を維持したままで、その中に酸化セリウムナノ粒子が分散した複合体が得られるから、酸化セリウムのもつ触媒性能を抑制した状態で紫外線遮蔽効果を発揮する、微粉末状の添加剤を提供することができる。 The fine particles of cerium oxide known so far are difficult to control the particle size, and when they are made fine particles, they tend to aggregate and only those having insufficient dispersibility can be obtained. According to the present invention, cerium oxide nanoparticles mixed in a well-dispersed state in zeolite are obtained, and if desired, a composite in which cerium oxide nanoparticles are dispersed therein while maintaining the crystal form and particle size of zeolite. Therefore, it is possible to provide an additive in the form of a fine powder that exhibits an ultraviolet shielding effect in a state where the catalytic performance of cerium oxide is suppressed.
後記する実施例にみるとおり、リンデＱゼオライトを使用して得た本発明の複合体を透過型電子顕微鏡により観察すると、六角板状形態の粒子内部に数１０ｎｍのナノサイズ結晶粒子が分散していることが確認でき、その粒径はきわめて均一である。得られた試料の光反射率を測定したところ、紫外領域において優れた遮蔽能を示すことが確認できた。 As seen in the examples described later, when the composite of the present invention obtained using Linde Q zeolite is observed with a transmission electron microscope, nano-sized crystal particles of several tens of nanometers are dispersed inside the hexagonal plate-like particles. The particle size is extremely uniform. When the light reflectance of the obtained sample was measured, it was confirmed that excellent shielding ability was exhibited in the ultraviolet region.
このように、酸化セリウムのナノ粒子がゼオライト中に分散した形で存在する本発明の複合体は、紫外線遮蔽材として役立つほか、前記の最近発表された総説（前掲非特許文献１）にあるように、研磨材、触媒、燃料電池電極材としての用途を有する。この複合体をプラスチック材料に添加したときは、その酸化を防止する作用を示すから、たとえば耐候性を向上させたプラスチックフィルムの製造に利用可能である。 As described above, the composite of the present invention in which nanoparticles of cerium oxide are dispersed in zeolite serves as an ultraviolet shielding material, and as described in the recently published review (Non-Patent Document 1). Furthermore, it has uses as an abrasive, a catalyst, and a fuel cell electrode material. When this composite is added to a plastic material, it exhibits the action of preventing its oxidation, and can be used, for example, in the production of a plastic film with improved weather resistance.
この事実は、酸化セリウムが、金属酸化物固溶体酸化セリウムである場合も同様である。酸化セリウムのナノ粒子がＣｅ以外の金属の酸化物を固溶体として取り込んだ粒子としてゼオライト中に分散した形で存在する本発明の複合体は、固溶した金属の種類に対応して、固有の特性をもつ。たとえば、ＰｒまたはＮｄがＣｅに固溶したものは、触媒としての性能が向上する。ＧｄまたはＳｍが固溶したものは、導電率が高まるし、Ｃａが固溶したものは、白色度が増し、かつ、触媒性能は低下して油脂などの有機物を分解させる傾向が低くなるため、とりわけ化粧品における紫外線遮蔽材として好適なものとなる。 This fact is the same when the cerium oxide is a metal oxide solid solution cerium oxide. The composite of the present invention in which cerium oxide nanoparticles are dispersed in zeolite as particles in which a metal oxide other than Ce is incorporated as a solid solution has unique characteristics corresponding to the type of the solid solution metal. It has. For example, when Pr or Nd is dissolved in Ce, the performance as a catalyst is improved. When Gd or Sm is dissolved, the conductivity is increased, and when Ca is dissolved, the whiteness is increased, and the catalyst performance is decreased, and the tendency to decompose organic substances such as fats and oils is reduced. In particular, it is suitable as an ultraviolet shielding material in cosmetics.
所望であれば、本発明の酸化セリウムまたは金属酸化物固溶体酸化セリウムのナノ粒子を、ゼオライトとの複合体から分離して単体として取得することができ、得られた単体ナノ粒子は、それらが本来有する性能を利用して、前述の諸用途に向けることができる。 If desired, the nanoparticles of the cerium oxide or metal oxide solid solution cerium oxide of the present invention can be obtained as a simple substance by separating from the complex with the zeolite. The performances possessed can be used for the various applications described above.
本発明で使用するゼオライトとしては、セリウムイオンをイオン交換によってその構造中に取り込むことが可能なものであれば、任意のゼオライトを選択することができる。紫外線遮蔽材などの用途にとって好適な板状の複合体を製造するには、クリノプチロライトなどの板状の結晶形態をもったゼオライトが好適である。なかでも、リンデＱゼオライトが好適である。リンデＱゼオライトは六角板状の結晶自形をもち、イオン交換容量が大きい。ゼオライトは、径０．５〜１０μｍ、厚さ１０〜２００ｎｍ、アスペクト比５以上のものが好ましい。 As the zeolite used in the present invention, any zeolite can be selected as long as it can incorporate cerium ions into its structure by ion exchange. In order to produce a plate-like composite suitable for applications such as an ultraviolet shielding material, zeolite having a plate-like crystal form such as clinoptilolite is suitable. Of these, Linde Q zeolite is preferred. Linde Q zeolite has a hexagonal plate-like crystal itself and a large ion exchange capacity. The zeolite preferably has a diameter of 0.5 to 10 μm, a thickness of 10 to 200 nm, and an aspect ratio of 5 or more.
ゼオライト中にあらかじめ存在するＫ＋イオンやＮａ＋イオンをＣｅ３＋イオンとイオン交換するには、セリウムの硝酸塩、塩化物等の可溶性塩の水溶液中にゼオライトを分散懸濁させ、１００℃以下の温度でイオン交換させる。イオン交換溶液のセリウムイオン濃度を選択することにより、ゼオライトのＣｅイオン交換率、すなわち、Ｃｅイオン含有量を制御することができる。 In order to exchange K + ions and Na + ions pre-existing in the zeolite with Ce 3+ ions, the zeolite is dispersed and suspended in an aqueous solution of a soluble salt such as cerium nitrate or chloride, and the temperature is below 100 ° C. Ion exchange with. By selecting the cerium ion concentration of the ion exchange solution, the Ce ion exchange rate of the zeolite, that is, the Ce ion content can be controlled.
イオン交換後、酸化性の雰囲気下で、または大気中でイオン交換体を焼成して、セリウム（III）→（IV）の酸化を行ない、酸化セリウムの粒子を生成させる。焼成温度を８００〜９００℃に選べば、酸化セリウムの生成と、ゼオライトの形態および粒径の維持とを両立させることが可能である。焼成温度を調節することにより、またそれに加えてイオン交換率を調節することにより、ゼオライト構造を維持した複合体を得ることもできるし、ゼオライトを分解させて非晶質とした複合体を得ることもできる。ゼオライト構造を維持する場合、所望であれば、イオン交換により、抗菌性を有する銀イオンなどの金属イオンを、その構造内に取り込ませることができる。 After the ion exchange, the ion exchanger is calcined in an oxidizing atmosphere or in the air to oxidize cerium (III) → (IV) to generate cerium oxide particles. If the calcination temperature is selected from 800 to 900 ° C., it is possible to achieve both the production of cerium oxide and the maintenance of the morphology and particle size of the zeolite. By adjusting the calcination temperature and additionally adjusting the ion exchange rate, it is possible to obtain a composite that maintains the zeolite structure, or to obtain a composite that is made amorphous by decomposing the zeolite. You can also. When maintaining the zeolite structure, if desired, metal ions such as silver ions having antibacterial properties can be incorporated into the structure by ion exchange.
以下の実施例において、試料のキャラクタリゼーションおよび性能の試験は、つぎのように行なった。
［イオン交換率の測定］
イオン交換試料を酸で分解し、誘導結合プラズマ発光分析装置（島津製作所製「ＩＣＰＳ−８０００」）によりＣｅおよびＫを定量して、イオン交換率を求める。
［イオン交換試料および加熱試料の結晶相の同定］
粉末Ｘ線回折（ＸＲＤ）（マック・サイエンスＭＸＰ３Ａ、理学電機ＲＩＮＴ−２５５０Ｈ）を使用。
［結晶形態の観察］
走査型電子顕微鏡（ＳＥＭ）（日本電子ＪＳＭ−６１００）および透過型電子顕微鏡（ＴＥＭ）（日本電子ＪＥＭ−２１００ＥＸ）により観察。
［反射特性］
自記分光光度計（日本分光Ｖ−５７０積分球付き）により、加熱試料の反射スペクトルを測定。
In the following examples, sample characterization and performance tests were performed as follows.
[Measurement of ion exchange rate]
An ion exchange sample is decomposed with an acid, and Ce and K are quantified with an inductively coupled plasma emission spectrometer (“ICPS-8000” manufactured by Shimadzu Corporation) to obtain an ion exchange rate.
[Identification of crystalline phases of ion exchange and heated samples]
Using powder X-ray diffraction (XRD) (Mac Science MXP3A, Rigaku Denki RINT-2550H).
[Observation of crystal morphology]
Observed with a scanning electron microscope (SEM) (JEOL JSM-6100) and a transmission electron microscope (TEM) (JEOL JEM-2100EX).
[Reflection characteristics]
The reflection spectrum of the heated sample is measured with a self-recording spectrophotometer (with JASCO V-570 integrating sphere).
酸化セリウムナノ粒子とゼオライトとの複合体（１）
平均粒径１．１７μｍ、厚さ約１００ｎｍの六角板状結晶形態を有するＫ型リンデＱゼオライト（Ｋ2Ｏ・Ａｌ2Ｏ3・２ＳｉＯ2・ｘＨ2Ｏ 以下、「リンデＱ」と略称する）を合成した。硝酸セリウムＣｅ(ＮＯ3)3の濃度を０．０２５，０．０５，０．１，０．１５，０．２および０．２５mol/Ｌに選んだ水溶液各６０ｍＬに、上記のリンデＱを８ｇずつ投入し、９０℃の恒温槽中に２４時間保持して、イオン交換処理を行なった。イオン交換をした試料をメンブレンフィルターにより濾過し、蒸留水で洗浄後、５０℃で乾燥して、セリウム交換リンデＱを得た。（以下、「イオン交換試料」という。）
Composite of cerium oxide nanoparticles and zeolite (1)
The average particle diameter of 1.17 .mu.m, K-type Linde Q zeolite having a hexagonal plate-like crystal form having a thickness of about 100nm (K 2 O · Al 2 O 3 · 2SiO 2 · xH 2 O hereinafter abbreviated as "Linde Q") Was synthesized. In each 60 mL of an aqueous solution in which the concentration of cerium nitrate Ce (NO 3 ) 3 was selected to be 0.025, 0.05, 0.1, 0.15, 0.2 and 0.25 mol / L, 8 g of the above Linde Q was added. Each was charged and kept in a constant temperature bath at 90 ° C. for 24 hours for ion exchange treatment. The ion-exchanged sample was filtered through a membrane filter, washed with distilled water, and then dried at 50 ° C. to obtain cerium-exchanged Linde Q. (Hereinafter referred to as “ion exchange sample”)
上記のイオン交換試料のイオン交換率を求め、イオン交換試料および加熱試料の結晶相を同定し、結晶形態を観察した。さらに、加熱試料の反射スペクトルを測定した。
表１に、イオン交換試料の定量分析結果を示す。リンデＱ内のＫ＋は、Ｃｅ３＋と交換することが確認された。
The ion exchange rate of the above ion exchange sample was determined, the crystal phases of the ion exchange sample and the heated sample were identified, and the crystal morphology was observed. Furthermore, the reflection spectrum of the heated sample was measured.
Table 1 shows the results of quantitative analysis of the ion exchange sample. It was confirmed that K + in Linde Q was exchanged with Ce 3+ .
表１ Ｃｅ交換リンデＱゼオライトの化学分析値
図１に、イオン交換試料を８００℃に加熱した試料のＸＲＤパターンを示す。この図から、イオン交換率１１．３％の試料は、８００℃に加熱したときに構造が崩れはじめているが、イオン交換率２５．４％以上の試料は、ゼオライト構造を維持していることがわかる。リンデＱは、Ｅｕ３＋およびＴｂ３＋とのイオン交換によって熱安定性が向上することが知られているが、Ｃｅ３＋イオン交換においても同様に熱安定性が向上することが明らかになった。加熱試料の結晶性はイオン交換率により異なることから、リンデＱの熱安定性の向上の度合は、Ｃｅ含有量に依存することがわかった。 In FIG. 1, the XRD pattern of the sample which heated the ion exchange sample at 800 degreeC is shown. From this figure, the sample with an ion exchange rate of 11.3% is beginning to lose its structure when heated to 800 ° C., but the sample with an ion exchange rate of 25.4% or more maintains the zeolite structure. Recognize. Linde Q is known to have improved thermal stability by ion exchange with Eu 3+ and Tb 3+ , but it has been clarified that thermal stability is improved in Ce 3+ ion exchange as well. Since the crystallinity of the heated sample differs depending on the ion exchange rate, it has been found that the degree of improvement in the thermal stability of Linde Q depends on the Ce content.
図２に、８００℃に加熱した加熱試料のＳＥＭ写真を示す。試験したＣｅイオン交換率１１．３〜８０．５％の全範囲にわたり、８００℃加熱試料はすべて、リンデＱの六角板状形態を保持していることを確認した。 In FIG. 2, the SEM photograph of the heating sample heated at 800 degreeC is shown. It was confirmed that all the 800 ° C. heated samples maintained the hexagonal plate shape of Linde Q over the entire range of the tested Ce ion exchange rate of 11.3 to 80.5%.
次に、加熱温度の影響を、イオン交換率４７．６％の試料を用いて検討した。イオン交換試料を、５０〜１０００℃の範囲内の所定の温度に加熱した。図３に加熱試料のＸＲＤパターンを、図４にＳＥＭ観察像を示す。 Next, the influence of the heating temperature was examined using a sample having an ion exchange rate of 47.6%. The ion exchange sample was heated to a predetermined temperature in the range of 50-1000 ° C. FIG. 3 shows an XRD pattern of the heated sample, and FIG. 4 shows an SEM observation image.
イオン交換率４７．６％のＣｅイオン交換試料は、８００℃まで結晶構造を維持することがわかった。この熱安定性の向上は、ＥｕおよびＴｂ交換リンデＱとほぼ同様である。さらに、８５０℃の加熱において構造がこわれはじめるが、９００℃の加熱においても六角板状の形態は保たれていることが分かった。 １０００℃の加熱では、リンデＱの構造は完全に分解し、六角板状体が溶融した形態となった。また、８５０℃以上の加熱試料から、２８．６°，３３．１°，４７．５°および５６．３°付近に幅広いピークが現れ、酸化セリウムの生成が確認された。酸化セリウムの回折ピークは、加熱温度の上昇とともに強くなっており、結晶の生長が推測される。 The Ce ion exchange sample having an ion exchange rate of 47.6% was found to maintain the crystal structure up to 800 ° C. This improvement in thermal stability is almost similar to Eu and Tb exchanged Linde Q. Furthermore, although the structure began to break upon heating at 850 ° C., it was found that the hexagonal plate shape was maintained even at 900 ° C. heating. By heating at 1000 ° C., the structure of Linde Q was completely decomposed and the hexagonal plate was melted. A wide peak appeared in the vicinity of 28.6 °, 33.1 °, 47.5 °, and 56.3 ° from the heated sample at 850 ° C. or higher, confirming the formation of cerium oxide. The diffraction peak of cerium oxide becomes stronger as the heating temperature increases, and the growth of crystals is estimated.
表２に、回折ピーク幅から結晶子サイズを求めた結果を示す。酸化セリウムは、その結晶粒径が約１５〜３０nmであるナノ粒子であることが推測された。また、加熱温度が高くなるほど、そしてイオン交換率が高くなるほど、言い換えるとＣｅ含有量が大きくなるほど、酸化セリウムの結晶子すなわち完全結晶のサイズが大きくなることが分かった。 Table 2 shows the result of obtaining the crystallite size from the diffraction peak width. It was estimated that cerium oxide was a nanoparticle having a crystal grain size of about 15 to 30 nm. It has also been found that the higher the heating temperature and the higher the ion exchange rate, in other words, the larger the Ce content, the larger the size of the cerium oxide crystallite, that is, the complete crystal.
表２ 酸化セリウムの結晶子サイズ
次に、イオン交換率４７．６％の９００℃加熱試料についてのＴＥＭ観察像を、図５に示す。十数nmの酸化セリウム粒子が生成し、六角板状のリンデＱの構造内に分散して存在していることが明らかとなった。酸化セリウム粒子の粒径はよく揃っていて、分布はおおよそ±２nm程度であった。 Next, FIG. 5 shows a TEM observation image of a 900 ° C. heated sample having an ion exchange rate of 47.6%. It has been clarified that cerium oxide particles having a size of several tens of nanometers are formed and dispersed in the structure of the hexagonal plate-shaped Linde Q. The cerium oxide particles had a uniform particle size and a distribution of about ± 2 nm.
図６に、種々の交換率でイオン交換したイオン交換試料を、８００℃に加熱した試料の反射スペクトルを示す。Ｃｅイオン交換リンデＱの加熱試料は、紫外線を吸収することが確認された。さらに、Ｃｅイオン交換率が大きくなるほど、紫外線吸収率は高くなった。この紫外線吸収率の増大は、リンデＱ構造内に存在する酸化セリウムの含有量と相関があると思われる。これに対し、Ｃｅイオン交換率４７．６％のイオン交換試料を、２００℃〜１０００℃の種々の温度に加熱した試料について反射スペクトルを調べ、図７の結果を得た。 FIG. 6 shows reflection spectra of samples obtained by heating ion exchange samples ion-exchanged at various exchange rates to 800 ° C. It was confirmed that the heated sample of Ce ion-exchanged Linde Q absorbs ultraviolet rays. Furthermore, the higher the Ce ion exchange rate, the higher the ultraviolet absorption rate. This increase in UV absorption seems to correlate with the content of cerium oxide present in the Linde Q structure. On the other hand, the reflection spectrum of a sample obtained by heating an ion exchange sample having a Ce ion exchange rate of 47.6% to various temperatures of 200 ° C. to 1000 ° C. was obtained, and the result of FIG. 7 was obtained.
一方、Ｃｅイオン交換率４７．６％のイオン交換試料を２００℃に加熱して得た試料についてＴＥＭ観察し、図８の写真を得た。このＴＥＭ像には、酸化セリウムの結晶が明確には見えない。図３のＸＲＤパターンもまた、酸化セリウム結晶の生成を示してはいない。しかし、図７の反射スペクトルにみるように、この試料は紫外線を吸収する性能はある。これらの事実から、この２００℃加熱の試料においては、酸化セリウムは生成したものの、結晶が発達するに至っていないものと解される。つまり、Ｃｅ−Ｏの結合が紫外線を吸収していると考えられる。要するに本発明の複合体における酸化セリウムとは、明確な結晶が生成した場合に限らず、この例のように結晶が発達していない場合であっても、Ｃｅ−Ｏの結合が存在するものをすべて包含する趣旨の語である。 On the other hand, a TEM observation was performed on a sample obtained by heating an ion exchange sample having a Ce ion exchange rate of 47.6% to 200 ° C. to obtain a photograph of FIG. In this TEM image, cerium oxide crystals are not clearly visible. The XRD pattern of FIG. 3 also does not show the formation of cerium oxide crystals. However, as shown in the reflection spectrum of FIG. 7, this sample has the ability to absorb ultraviolet rays. From these facts, it is understood that in the sample heated at 200 ° C., cerium oxide was generated, but crystals did not develop. That is, it is considered that the Ce—O bond absorbs ultraviolet rays. In short, the cerium oxide in the composite of the present invention is not limited to the case where a clear crystal is formed, and even in the case where the crystal is not developed as in this example, the cerium oxide is one having a Ce-O bond. It is a word that encompasses all.
酸化セリウムナノ粒子とゼオライトとの複合体（２）
Ｎａ型ゼオライトＸ（Ｎａ2Ｏ・Ａｌ2Ｏ3・２．５ＳｉＯ2・ｘＨ2Ｏ）をテフロン（登録商標）密閉容器に８ｇ量り取り、Ｃｅ(ＮＯ3)3イオン交換溶液（Ｃｅ(ＮＯ3)3濃度：０．１mol/Ｌ）を６０ml加え、９０℃の恒温槽中で、２４時間イオン交換処理を行なった。イオン交換試料は、濾過および洗浄の後、５０℃で乾燥した。イオン交換によって得られたイオン交換試料を、大気中で９００℃に１時間加熱し、加熱試料を得た。
Composite of cerium oxide nanoparticles and zeolite (2)
Na zeolite X (Na 2 O · Al 2 O 3 · 2.5SiO 2 · xH 2 O) Teflon sealed container to 8g weighed, Ce (NO 3) 3 ion exchange solution (Ce (NO 3 ) 3 concentration: 0.1 mol / L) was added in an amount of 60 ml, and ion exchange treatment was performed in a thermostat at 90 ° C. for 24 hours. The ion exchange sample was dried at 50 ° C. after filtration and washing. An ion exchange sample obtained by ion exchange was heated to 900 ° C. for 1 hour in the air to obtain a heated sample.
この加熱試料をＸ線回折分析により観察したところ、ゼオライトＸのピークは失われて、ゼオライト構造が完全に崩壊していることがわかった。それに代わって、２８．６°，３３．１°，４７．５°および５６．３°付近に幅広いピークが現れ、酸化セリウムが生成していることが確認された。 When this heated sample was observed by X-ray diffraction analysis, it was found that the zeolite X peak was lost and the zeolite structure was completely destroyed. Instead, broad peaks appeared in the vicinity of 28.6 °, 33.1 °, 47.5 °, and 56.3 °, confirming the formation of cerium oxide.
他の金属酸化物を固溶した酸化セリウムナノ粒子
Ｃｅ(ＮＯ3)3の濃度を０．１mol/Ｌとして用意したイオン交換用の溶液に、Ｃｅ以外の金属のイオン（Ｃａイオン、Ｐｒイオン、Ｎｄイオン、ＳｍイオンまたはＧｄイオン）をそれぞれ内割で２０モル％添加することによって、２種の金属イオンが混合した溶液を調製した。Ｋ型リンデＱ（Ｋ2Ｏ・Ａｌ2Ｏ3・２ＳｉＯ2・ｘＨ2Ｏ）をテフロン（登録商標）密閉容器に８ｇ量り取り、上記混合溶液を６０mＬ加え、９０℃の恒温槽中で２４時間、イオン交換処理を行なった。イオン交換試料は、濾過し洗浄した後、５０℃で乾燥し、セリウム−他の金属イオン複合交換ゼオライトを得た。このイオン複合交換ゼオライトを、大気中で９００℃に１時間加熱し、加熱試料を得た。
In a solution for ion exchange prepared at a concentration of 0.1 mol / L of cerium oxide nanoparticles Ce (NO 3 ) 3 in which other metal oxides are dissolved , ions of metals other than Ce (Ca ions, Pr ions, Nd Ion, Sm ion, or Gd ion) was added in an internal ratio of 20 mol% to prepare a solution in which two kinds of metal ions were mixed. 8 g of K-type Linde Q (K 2 O.Al 2 O 3 .2SiO 2 .xH 2 O) is weighed into a Teflon (registered trademark) sealed container, 60 mL of the above mixed solution is added, and it is kept in a constant temperature bath at 90 ° C. for 24 hours. The ion exchange treatment was performed. The ion exchange sample was filtered and washed, and then dried at 50 ° C. to obtain a cerium-other metal ion composite exchange zeolite. This ion composite exchanged zeolite was heated to 900 ° C. for 1 hour in the air to obtain a heated sample.
これらの加熱試料をＸ線回折により分析したところ、９００℃以上の加熱によってリンデＱの構造は完全に崩壊したことがわかった。この場合も、リンデＱのピークに代わって、２８．６°，３３．１°，４７．５°および５６．３°付近に幅広いピークが現れ、酸化セリウムが生成していることが確認された。走査型電子顕微鏡で観察した結果、すべての混合溶液から得られた試料が、六角板状の形態を維持していることがわかった。 When these heated samples were analyzed by X-ray diffraction, it was found that the structure of Linde Q was completely destroyed by heating at 900 ° C. or higher. Also in this case, instead of the Linde Q peak, a wide range of peaks appeared around 28.6 °, 33.1 °, 47.5 °, and 56.3 °, confirming the formation of cerium oxide. . As a result of observation with a scanning electron microscope, it was found that samples obtained from all the mixed solutions maintained a hexagonal plate shape.
走査型電子顕微鏡に付属のエネルギー分散型蛍光Ｘ線分析により組成分析を行なったところ、下記のデータが得られ、いずれの試料も、セリウムと他の金属が共存していることが確認された。
表３ 金属酸化物固溶酸化セリウムナノ粒子の蛍光Ｘ線分析
Table 3 X-ray fluorescence analysis of metal oxide solid solution cerium oxide nanoparticles
酸化セリウムナノ粒子の分離
実施例１において得た、リンデＱゼオライトに７１．４％のイオン交換率でＣｅをイオン交換したものを、９００℃に加熱した。得られた酸化セリウム−ゼオライト複合体０．１ｇに、４６％ＨＦ溶液５ｍＬと３６％ＨＣｌ溶液５ｍＬとを加え、加熱してゼオライトを溶解した。いったん蒸発乾固したのち、水１０ｍＬと少量のＨＣｌを加えて、可溶性の成分を溶解して除いた後、濾過洗浄した。得られた酸化セリウムナノ粒子単体をＴＥＭ観察して、図９の写真を得た。
Separation of cerium oxide nanoparticles The Linde Q zeolite obtained in Example 1, which was ion exchanged with Ce at an ion exchange rate of 71.4%, was heated to 900C. To 0.1 g of the obtained cerium oxide-zeolite composite, 5 mL of 46% HF solution and 5 mL of 36% HCl solution were added and heated to dissolve the zeolite. After evaporation to dryness, 10 mL of water and a small amount of HCl were added to dissolve and remove soluble components, followed by filtration and washing. The obtained cerium oxide nanoparticles alone were observed with a TEM to obtain a photograph of FIG.
図は、いずれも本発明の実施例のデータであって、それぞれ下記の内容である。
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