Method for producing conductive mayenite compound powder
|発明の名称 （英語）||Method for producing conductive mayenite compound powder|
|発明の概要（英語）||If a conductive mayenite compound having a large specific surface area is obtained, the usefulness thereof in respective applications is remarkably increased. A conductive mayenite compound powder having a conduction electron density of 1015 cm3 or more and a specific surface area of 5 m2g-1 or more is produced by: (1) a step for forming a precursor powder by subjecting a mixture of a starting material powder and water to a hydrothermal treatment; (2) a step for forming a mayenite compound powder by heating and dehydrating the precursor powder; (3) a step for forming an activated mayenite compound powder by heating the compound powder in an inert gas atmosphere or in a vacuum; and (4) a step for injecting electrons into the mayenite compound through a reduction treatment by mixing the activated mayenite compound powder with a reducing agent.|
In the CaO, Al2 O3, SiO2 in the calcium aluminosilicate as a constituent component, there is a mineral entitled mayenite material, will be provided with crystal is of the same type crystal structure is referred to as "mayenite type compound" of the compound. There is known a report, the mayenite type compound has 12CaO·7Al2 O3 (hereinafter referred to as "C12A7") such a representative composition, C12A7 crystal has a specific crystal structure: contains 2 molecules present in the unit cell of the group consisting of oxygen ions to oxygen ions 66 2 "free oxygen" Inclusion in a manner that the space within the cage formed by the crystal framework (Non-Patent Document 1).
After 2003, the present invention has been revealed that the mayenite type compound free contained in the person may be a variety of anion replaces oxygen ions. In particular, it is maintained in a strong reducing atmosphere of C12A7, it can be replaced with electrons will all of the free oxygen ions. The free oxygen ions with electrons according to formula C12A7 a replacement can be written as [Ca24 Al28 O64 ]4+ (e-)4 (hereinafter referred to as " C12A7: e- "). In addition, this way will be referred to as a material obtained by anionic substituted for electrons "electronic product (electride) ", having a display good electron transfer characteristics of the electronic product features (Non-Patent Document 2).
The present invention has been found, using the following method can be obtained with 1x1019 cm-3 or more of the conduction electrons of the concentration of C12A7: e- and C12A7 is homocysteine with a compound (Patent Document 1): (a) to a single crystal of C12A7, fine powder is isostatically pressed molded article (molded article hydrostatic Ritz-pressure pu su) in an alkali metal or alkaline earth metal vapor at 600-800 °C method of storing under, (b) a non-reactive ions to an ion-Injected into C12A7 method of a thin film or (c) of the fine powder of C12A7 an isostatic pressing press-molded product was melted in a reducing atmosphere, directly from the melt of the curing method.
In addition, the present invention applied for a patent invention of a person to as follows: a good melt the raw material for the conductive mayenite compound, in a low oxygen partial pressure is kept in an atmosphere followed by cooling solidification of the invention according to the method (Patent Document 2), the raw material powder was subjected to elevated temperature is maintained and using solid-phase reaction for sintering resulting baked product, and the sinter was pulverized, grinding the resultant powder, the powder has a press-molded product or the molded was cultured at 1200-1350 °C in the sintered body obtained by baking the addition of carbon, Al, reducing agent such as Ti, to 600-1415 °C to a heat treatment so as to impart electrical conductivity (i.e., displacement of the free oxygen ions and electrons) of the invention according to the method (Patent Document 3, 4). Further, C12A7 single crystal in a titanium metal was (Ti) vapor was subjected to annealing, exhibiting a metallic electrically conductive C12A7 has been successfully acquired: e-, for their production methods and its use as an electron emission material related to the invention applied for a patent (Patent Document 5).
As a method for producing a conductive mayenite type compound, such as the method of the invention is related to the following patent applications: through the non-aqueous solution of the raw material in a 500-1500 °C for heat baking method is obtained from the master 12Ca1-x Srx O7 Al2 O3 (x=0-1) composite oxide represented by a film of 700-1500 °C heat and the method of the reduction treatment (Patent Document 6); the mixed raw material in a reducing atmosphere, an inert atmosphere or vacuum to an oxygen partial pressure atmosphere of not more than 1000Pa, to 1200-1415 °C method of the heat (Patent Document 7); the metal Al, a metal reducing agent such as Ca with the mixture of raw materials at 1200-1415 °C sintering, or at 1415-1600 °C molten method (Patent Document 8); mayenite type compound powder is calcined at will be 300-1200 °C heat to form a sintered body having open pores, the obtained sintered body in a reducing atmosphere at 1200-1450 °C method of the heat (Patent Document 9) and the like.
With regard to revealing that the metal electrically conductive C12A7: e-, 11:7 through may also be mixed in proportion to CaCO3 and the Al2 O3, 1300 °C and used to heat the metal product of Ca vapor atmosphere so as to directly heat the synthetic powder (Non-Patent Document 3). With respect to the conductive mayenite type compound, is applied to the electron emitters, field emission display device, a cold cathode fluorescent tube, flat lighting devices and electron emission material (Patent Document 10), a discharge lamp electrode (Patent Document 11) and the like.
Further, Al of the conductive mayenite type compound underway on of the Ga or In C12A7 a portion of the mayenite type compound obtained by replacing applies for relevance to the invention, it is suitable for use as a PDP protective film material, an organic EL device in high-temperature heat treatment is required such as a charge-injecting material of an electrode material (Patent Document 12).
The present invention are as follows invention applied for a patent on the person, which has: on a conductive mayenite type compound is supported on a Ru, Fe or the like supporting a metal catalyst of the invention according to the ammonia synthesis reaction (Patent Document 13), using a conductive mayenite type compound and the carbon dioxide is reduced to carbon monoxide of the invention according to the method (Patent Document 14). In addition it is known, with respect to C12A7, even if the non-conductive material also serving as a catalyst, or the use of a catalyst support, for example, through a complex of a raw material solution was subjected to spray-drying was performed at 1300-1400 °C burn-in 2 hours or more to obtain soft olefin generating water vapor as a catalyst for decomposition catalyst (Patent Document 15). Recently there is proposed a through by a hydrothermal method, sol-gel approach for synthesis of a precursor followed by calcination method of obtaining a high specific surface area of the carrier of the method (Non-Patent Document 4, 5).
Also reported the following: moisture-containing atmosphere to be placed in a C12A7 sets the value of hydroxyl ions (OH-) for inclusion in the cage, even at elevated temperatures is not easily disengaged (non-Patent Document 6).
Prior Art Document
Patent Document 1:WO2005/000741
Patent Document 2:WO2005/077859
Patent Document 3:WO2006/129674
Patent Document 4:WO2006/129675
Patent Document 5:WO2007/060890
Patent Document 6: Japanese Laid-Open Publication No.2009-107858
Patent Document 7: Japanese Laid-Open Publication No.2010-132467
Patent Document 8: Japanese Laid-Open Publication No.2012-082081
Patent Document 9: Japanese Laid-Open Publication No.2012-126618
Patent Document 10:WO2006/112455
Patent Document 11:WO2011/024821
Patent Document 12: Japanese Laid-Open Publication No.2009-203126
Patent Document 13:WO2012/077658
Patent Document 14: Japanese Laid-Open Publication No.2012-025636
Patent Document 15: US Patent Specification No. No.6,696,614
Non-Patent Document 1: Von Hans Bartl und Thomas Scheller, "N.Jahrbuch F.Mineralogie.Monatshefte", 35,547-552, (1970)
Non-Patent Document 2: S.Matsuishi,Y.Toda,M.Miyakawa,K.Hayashi,T.Kamiya,M.Hirano,I.Tanaka and H.Hosono, "Science", 301,626-629, (2003)
Non-Patent Document 3: S.Matsuishi,T.Nomura,M.Hirano,K.Kodama,S.Shamoto and H.Hosono, "Chemistry of Materials", 21,2589-2591, (2009)
Non-Patent Document 4: L.Gong,Z.Lin,S.Ning,J.Sun,J.Shen,Y.Torimoto and Q.Li, "Material Letters", 64,1322-1324, (2010)
Non-Patent Document 5: C.Li,D.Hirabayashi and K.Suzuki, "Materials Research Bulletin", 46,1307-1310, (2011)
Non-Patent Document 6: K.Hayashi,M.Hirano and H.Hosono, "J.Phys.Chem.B", 109,11900-11906, (2005)
1. One conductive mayenite type compound, a concentration of conduction electrons 1x1015 cm-3 or more, characterized in, specific surface area of 5m2 g-1 or more.
2. Conductive mayenite type compound according to claim 1, characterized in, conduction electron concentration of 2.3x1021 cm-3 or less.
3. Conductive mayenite type compound according to claim 1, characterized in, specific surface area of 31m2 g-1 or less.
4. Conductive mayenite type compound according to claim 1, characterized in, has a primary particle diameter of not more than 100 nm in a powder form, or in the porous body having fine pores of the structure of the block.
5. A supported metal catalyst, wherein the metal supported on a support, characterized in, carrier is a conductive mayenite type compound, the conductive mayenite type compound of the conduction electrons at a concentration of 1x1015 cm-3 or more and specific surface area of 5m2 g-1 or more.
6. The supported metal catalyst according to claim 5, characterized in, metal is a transition metal.
7. The supported metal catalyst according to claim 6, characterized in, to an active transition metal with ammonia.
8. Claim 5-7 supported metal catalyst according to any one, characterized in, vector of the specific surface area of 31m2 g-1 or less.
9. The supported metal catalyst according to claim 5, characterized in, has a primary particle diameter of not more than 100 nm in a powder form, or in the porous body having fine pores of the structure of the block.
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