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WO2012123184A1 - Particules d'oxyde de fer enrobées - Google Patents

Particules d'oxyde de fer enrobées Download PDF

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Publication number
WO2012123184A1
WO2012123184A1 PCT/EP2012/051827 EP2012051827W WO2012123184A1 WO 2012123184 A1 WO2012123184 A1 WO 2012123184A1 EP 2012051827 W EP2012051827 W EP 2012051827W WO 2012123184 A1 WO2012123184 A1 WO 2012123184A1
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WO
WIPO (PCT)
Prior art keywords
region
particles
temperature
maghemite
magnetite
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.)
Ceased
Application number
PCT/EP2012/051827
Other languages
German (de)
English (en)
Inventor
Stipan Katusic
Peter Kress
Harald Herzog
Uwe Paulmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Evonik Operations GmbH
Original Assignee
Evonik Degussa GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Evonik Degussa GmbH filed Critical Evonik Degussa GmbH
Publication of WO2012123184A1 publication Critical patent/WO2012123184A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/0018—Mixed oxides or hydroxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
    • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
    • C09C1/22—Compounds of iron
    • C09C1/24—Oxides of iron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area

Definitions

  • the invention relates to processes for the preparation of silica-coated iron oxide particles.
  • Adhesive composites or for the crosslinking of polymers It has proven to be advantageous to use coated magnetic particles.
  • the shell is attributed the function, on the one hand to improve the incorporation into the networks and on the other to prevent unwanted growth of the magnetic phases.
  • WO03 / 58649 discloses a process for the preparation of silica
  • coated iron oxide having a content of silicon of less than 20 wt .-% disclosed in which a silicate separation from water glass or silica sol on the iron oxide particles.
  • DE-A-102006054173 discloses a process for the preparation of porous magnetic silica particles.
  • a pH-value modifier and an organic pore-forming agent are added to a liquid reaction mixture which contains magnetic particles and at least one compound serving as the silica source, and the resulting reaction mixture is subsequently spray-dried.
  • WO02 / 09125 there is disclosed an oil dispersion crosslinking process for preparing spherical pore size magnetic silica particles comprising silica hydrosol formed by acid-catalytic hydrolysis of an aqueous silane dispersion and comprising a magnetic colloid or ferrofluid or Magnetic particles is mixed, in a water-immiscible dispersed organic phase and crosslinked during the dispersion process by adding a base.
  • EP-A-961653 discloses a process for the preparation of low Curie temperature core-shell particles wherein the shell is silica and the core is superparamagnetic iron oxides wherein a silica precursor is added to a dispersion of the core material, and subsequently by adding acid, the pH is lowered to 6 to 9.
  • WO2010 / 063557 discloses iron-silicon oxide particles having a core-shell structure having a BET surface area of 10 to 80 m 2 / g, a shell thickness of 2 to 30 nm and an iron oxide content of 60 to 90 Wt .-%, wherein the core is crystalline and the iron oxides comprises hematite, magnetite and maghemite, the shell consists of amorphous silica and between shell and core at least partially present one or more compounds consisting of the elements silicon, iron and oxygen , It is obtained by a flame oxidation / flame hydrolysis process in which a mixture of an aerosol of a
  • Iron oxide precursor and a vaporous silicon compound burns under defined conditions in a flame.
  • the technical object of the present invention is to provide further methods resulting in coated magnetic particles.
  • the core as in the case of the disclosed in WO2010 / 063557 gas phase method, in addition to magnetic iron oxides, also contain the non-magnetic hematite, since obviously the combination of magnetic iron oxides and hematite represents a particularly advantageous composition for inductive heating.
  • a first object of the invention is a process for the production of particles with an envelope of amorphous silica and a core containing hematite and at least one further iron oxide selected from magnetite and maghemite, wherein at a temperature of 800 to 1200 ° C, preferably from 900 to 1 100 ° C, comprising a stream
  • the temperatures of 800 to 1200 ° C required in this process according to the invention can be provided for example in the form of an external heating.
  • they are formed by a flame resulting from the ignition of a mixture containing at least one hydrogen-containing fuel gas and an oxygen-containing gas.
  • hydrogen-containing fuel gases are hydrogen, methane, ethane and / or propane, wherein
  • Hydrogen is particularly preferably used.
  • the molar ratio of O 2 in the oxygen-containing gas / hydrogen-containing fuel gas is preferably 0.8 to 1.5, and more preferably 1.05 to 1.3.
  • an internal flame the reaction of the starting materials, iron oxide or iron oxide and Siliciumdioxidprecursor, in the presence of the flame or their
  • Reaction products such as water in the case of a hydrogen / oxygen flame. In an external flame, this only provides the temperature for the implementation of
  • the starting materials are ready while the reaction products are conducted separately from the reaction or are only subsequently combined with the products of the reaction.
  • Water vapor is formed by the reaction of the hydrogen-containing fuel gas and the oxygen-containing gas. This may be part or all of the amount needed in the process of the invention
  • the average residence time in the region of the reactor in which the temperature of 800 to 1200 ° C is preferably 10 ms to 1 s.
  • a second aspect of the invention is a process for producing particles comprising an amorphous silica shell and a core containing hematite and at least one further iron oxide selected from magnetite and maghemite, in which
  • reaction and optionally the reaction mixture leaving the second region brings to reaction and optionally the reaction mixture leaving the second region, preferably by feeding water, and subsequently separating the solid from gaseous or vaporous substances.
  • a third object of the invention is a process for the production of particles with an envelope of amorphous silica and a core containing hematite and at least one further iron oxide selected from magnetite and maghemite, in which
  • the region of the reactor brings to reaction and optionally in a second, the first subsequent, the region of the reactor at a temperature of 400 to 800 ° C, preferably 600 to 650 ° C, wherein the temperature in the second region is lower than in the first region, comprising a current
  • reaction and optionally the reaction mixture leaving the second region brings to reaction and optionally the reaction mixture leaving the second region, preferably by feeding water, and subsequently separating the solid from gaseous or vaporous substances.
  • the temperatures of 650 to 1000 ° C required in the process according to the invention can be provided for example in the form of an external heating.
  • they are formed by a flame resulting from the ignition of a mixture containing at least one hydrogen-containing fuel gas and an oxygen-containing gas.
  • hydrogen-containing fuel gases are hydrogen, methane, ethane and / or propane, wherein
  • Hydrogen is particularly preferably used.
  • the molar ratio of O 2 in the oxygen-containing gas / hydrogen-containing fuel gas is preferably 0.8 to 1.5, and more preferably 1.05 to 1.3.
  • an internal flame the reaction of the starting materials, iron oxide or iron oxide and Siliciumdioxidprecursor, in the presence of the flame or their
  • FIG. 1 shows schematically a method with an internal flame
  • FIG. 2 a method with an external flame.
  • Water vapor is formed by the reaction of the hydrogen-containing fuel gas and the oxygen-containing gas. This may be part or all of the amount needed in the process of the invention
  • the average residence time in the region of the reactor in which the temperature is from 650 to 1000 ° C. is preferably 10 ms to 2 s.
  • the average residence time in the region of the reactor in which the temperature is from 400 to 800 ° C. is preferably from 0.1 to 10 s.
  • the embodiment of the invention in which the silicon compound is introduced both in the temperature range of 650 to 1000 ° C as well as in the temperature range of 400 to 800 ° C, is preferably such that more than 50 mol% of
  • Silicon compound more preferably 60 to 90 mol%, are introduced in the temperature range of 400 to 800 ° C.
  • the magnetite and / or hematite particles can be used either in powder form or as a dispersion. Preferably, they are used as an aerosol, either as a solid / gaseous aerosol
  • the carrier gas used is generally air or nitrogen. If a dispersion of maghemite and / or magnetite particles is used, their content in the dispersion is generally from 0.5 to 25% by weight, preferably from 3 to 10% by weight.
  • the dispersion may contain dispersing additives such as polyacrylic acid and salts thereof. The simpler method variant, however, is the
  • maghemite and / or magnetite particles as powder.
  • Maghemite particles have, independently of each other, a middle one
  • the silicon compounds used in the process according to the invention are hydrolyzable and / or oxidizable compounds. These are preferably selected from the group consisting of SiCl 4 , CH 3 SiCl 3 , (CH 3 ) 2 SiCl 2 , (CH 3 ) 3 SiCl, HSiCl 3 , (CH 3 ) 2 HSiCl and CH 3 C 2 H 5 SiCl 2 , H 4 Si, Si (OC 2 H 5 ) 4, Si (OCH 3 ) 4 or mixtures of the abovementioned. Particularly preferably, SiCl 4 , and Si (OC 2 H 5 ) 4 can be used.
  • SiCl 4 can be used in the process steps which are carried out at the higher temperature, namely from 800 to 1200 ° C. or 650 to 1000 ° C.
  • Si (OC 2 H 5 ) 4 can be completely particularly preferably can be used in the process steps which are carried out at the lower temperature, namely from 400 to 800 ° C.
  • Maghemite particles and / or magnetite particles to the silicon compound calculated as Si0 2 , preferably 10:90 to 95: 5 amount.
  • Si0 2 preferably 10:90 to 95: 5 amount.
  • Induction temperatures sought so that a weight ratio of 60:40 to 95: 5 is to be regarded as particularly preferred.
  • the embodiment of the invention in which the silicon compound is introduced both in the temperature range of 650 to 1000 ° C as well as in the temperature range of 400 to 800 ° C, is preferably such that more than 50 mol% of
  • Silicon compound more preferably 60 to 90 mol%, are introduced in the temperature range of 400 to 800 ° C.
  • the particles produced according to the methods of the invention consist of a dense envelope of amorphous silica and a core containing hematite and at least one further iron oxide selected from magnetite and maghemite.
  • the processes according to the invention are preferably carried out such that the core contains magnetite, maghemite and hematite. Particularly preferred is a
  • the BET surface area of the particles is preferably 5 to 80 m 2 / g.
  • the thickness of the shell is preferably from 3 to 40 nm.
  • Core constituents are preferably less than 100 nm. Particularly preferred is the crystallite size of hematite thus determined 40 to 70 nm, of magnetite 30 to 90 nm and of maghemite 20 to 40 nm. In contrast to those obtainable in the prior art with silica coated
  • Iron oxide particles allow the inventive method, the production of particles with particularly high heating rates. During production by the processes according to the invention, complex conditions occur at high temperatures
  • Transformations of the iron oxides which apparently lead to a particularly favorable arrangement of the core components, which are attached via chemical bonds to the amorphous silicon dioxide shell. Ensure magnetite and maghemite the electromagnetic coupling of the energy into the core, while hematite provides for a high thermal conductivity.
  • the content of iron oxide is determined by digestion with NaOH, dissolution in dilute H 2 S0 4 and subsequent iodometric titration.
  • the BET surface area is determined according to DIN 66131.
  • the hematite is clearly identifiable because of the freestanding reflexes.
  • the maghemite is significantly detectable by the reflexes (1 10) and (211) in the anterior area of the bowel.
  • a quantitative phase analysis is performed (error about 10% relative).
  • Quantitative phase analysis is performed using set 60 of the ICDD database PDF4 + (2010).
  • the quantitative phase analysis and the determination of the crystallite sizes are carried out with the Rietveld program SiroQuant®, Version 3.0 (2005).
  • the thickness of the outer shell is determined by transmission electron microscopy (TEM). In addition, it is checked whether the shell is tight. By this is meant that upon contact of the particles with hydrochloric acid less than 50 ppm of iron are detectable. At room temperature, 0.33 g of the particles are brought into contact with 20 ml of 1 N hydrochloric acid solution for 15 minutes. Part of the solution is subsequently analyzed for iron by means of suitable analysis techniques, for example ICP (inductively coupled plasma spectroscopy).
  • ICP inductively coupled plasma spectroscopy
  • the heating time up to a temperature of 100 ° C is determined in a silicone composition.
  • the silicone composition is obtained by mixing 33 g ELASTOSIL ® E50, Fa. Momentive Performance Materials, 13 g of silicone oil type M 1000, Fa. Momentive
  • Maghemite Auer-Remy, average particle size 20 to 50 nm, specific surface area> 30 m 2 / g, approximately spherical.
  • Magnetite Auer-Remy, average particle size 20 to 30 nm, specific surface area> 60 m 2 / g, spherical.
  • Examples 1 to 3 are carried out by means of indirect flame, examples 4 to 6 by means of direct flame.
  • EXAMPLE 1 In a first region of a flow-through reactor, a mixture of 1250 g / h of pulverulent maghemite and 4.5 Nm 3 / h of air is subjected to a temperature-controlled treatment in a high-temperature zone.
  • the high-temperature zone is formed by an external hydrogen / oxygen flame, which results from ignition of 6.5 Nm 3 / h of hydrogen and 30 Nm 3 / h of air.
  • the mean residence time of the reaction mixture in this first region is about 0.1 s.
  • the temperature 50 cm below the burner mouth is 825 ° C.
  • Reaction mixture in the second range is 0.9 s.
  • the temperature 20 cm above the point of addition is about 640 ° C.
  • reaction mixture is cooled and the resulting solid is deposited on a filter of the gaseous substances.
  • the solid has an iron oxide content, calculated as Fe 2 O 3 , of 89% by weight. Its BET surface area is 30 m 2 / g. The proportions by weight of maghemite,
  • Magnetite and hematite are 54, 9 and 37%.
  • the heating temperature after 60 s is 312 ° C. After treatment with hydrochloric acid, 15 ppm iron is detectable.
  • Example 2 is carried out analogously to Example 1, but the atomization of the magnetite takes place in a reducing atmosphere. Furthermore, the flame parameters are selected differently than in Example 1, so that the temperature in the first region is lower.
  • Example 3 is carried out analogously to Example 1, but a 1: 1 mixture, each 0.325 kg / h, of magnetite and maghemite is used.
  • Example 4 In a first region of a flow reactor, a mixture of 800 g / h of pulverulent maghemite and 4.5 Nm 3 / h of air are reacted in a hydrogen / oxygen flame. The flame results from the ignition of a
  • reaction mixture is cooled and the resulting solid is deposited on a filter of the gaseous substances.
  • the solid has an iron oxide content, calculated as Fe 2 O 3 , of 82% by weight. Its BET surface area is 30 m 2 / g. The proportions by weight of maghemite, magnetite and hematite are 20, 62 and 18%. The heating temperature after 60 s is 352 ° C. After treatment with hydrochloric acid, 25 ppm iron is detectable.
  • Example 5 is carried out analogously to Example 4, but magnetite is used instead of maghemite.
  • Example 6 is carried out analogously to Example 4, but a 1: 1 mixture of magnetite and maghemite is used and the atomization takes place in a reducing atmosphere.
  • the starting materials and reaction conditions as well as the physicochemical properties of the powders obtained are summarized in Table 1.
  • the examples show that it is possible by means of the processes according to the invention to produce silica-coated iron oxide particles.
  • the short-term high-temperature treatment makes it possible to modify the iron oxide particles used so that the core of the particles produced by the process according to the invention contains three iron oxide modifications, namely, irrespective of the iron oxide, magnetite, maghemite and hematite used.
  • the composition of the core can be varied as shown in the examples and leads to high temperatures during inductive heating. Table 1: Starting materials and reaction conditions; physicochemical data

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • Inorganic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Composite Materials (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Compounds Of Iron (AREA)

Abstract

L'invention concerne la production de particules constituées d'une enveloppe de dioxyde de silicium amorphe et d'un noyau qui contient de l'hématite et au moins un autre oxyde de fer choisi parmi la magnétite et la maghémite. Dans ce procédé, on fait réagir à haute température les particules de magnétite et/ou les particules de maghémite, un gaz contenant de l'oxygène ou un gaz contenant de l'hydrogène, de la vapeur d'eau et un composé de silicium, que l'on refroidit par la suite le cas échéant et on sépare la matière solide des matières à l'état de gaz ou de vapeurs.
PCT/EP2012/051827 2011-03-14 2012-02-03 Particules d'oxyde de fer enrobées Ceased WO2012123184A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE201110005489 DE102011005489A1 (de) 2011-03-14 2011-03-14 Umhüllte Eisenoxidpartikel
DE102011005489.8 2011-03-14

Publications (1)

Publication Number Publication Date
WO2012123184A1 true WO2012123184A1 (fr) 2012-09-20

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WO (1) WO2012123184A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110167886B (zh) * 2017-01-09 2022-05-24 赢创运营有限公司 借助喷雾热解法制备金属氧化物的方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4280918A (en) * 1980-03-10 1981-07-28 International Business Machines Corporation Magnetic particle dispersions
DE102008044384A1 (de) * 2008-12-05 2010-06-10 Evonik Degussa Gmbh Eisen-Silicium-Oxidpartikel mit einer Kern-Hülle-Struktur

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69810080T2 (de) 1997-01-21 2003-10-09 Grace W R & Co Siliciumdioxidadsorbent auf magnetischem träger
DE10035953A1 (de) 2000-07-21 2002-01-31 Fraunhofer Ges Forschung Sphärische, magnetische Silica-Partikel mit einstellbarer Teilchen- und Porengröße sowie einstellbarem Magnetgehalt für die Aufreinigung von Nukleinsäuren und anderen Biomolekülen
DE10201084A1 (de) 2002-01-14 2003-07-24 Bayer Ag Siliziumhaltige Magnetpartikel, Verfahren zu deren Herstellung und Verwendung der Partikel
DE102006054173A1 (de) 2006-11-16 2008-05-21 Qiagen Gmbh Verfahren zur Herstellung von magnetischen Kieselsäurepartikeln

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4280918A (en) * 1980-03-10 1981-07-28 International Business Machines Corporation Magnetic particle dispersions
DE102008044384A1 (de) * 2008-12-05 2010-06-10 Evonik Degussa Gmbh Eisen-Silicium-Oxidpartikel mit einer Kern-Hülle-Struktur

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