WO2006048400A1 - Volume-doped titanium dioxide composites - Google Patents

Volume-doped titanium dioxide composites Download PDF

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Publication number
WO2006048400A1
WO2006048400A1 PCT/EP2005/055583 EP2005055583W WO2006048400A1 WO 2006048400 A1 WO2006048400 A1 WO 2006048400A1 EP 2005055583 W EP2005055583 W EP 2005055583W WO 2006048400 A1 WO2006048400 A1 WO 2006048400A1
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WIPO (PCT)
Prior art keywords
titanium dioxide
composites
volume
dioxide composites
photocatalytic
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PCT/EP2005/055583
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German (de)
French (fr)
Inventor
Christian Sattler
Lamark De Oliveira
Christian Jung
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Deutsches Zentrum für Luft- und Raumfahrt e.V.
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Publication of WO2006048400A1 publication Critical patent/WO2006048400A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/16—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes
    • B01J31/18—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes containing nitrogen, phosphorus, arsenic or antimony as complexing atoms, e.g. in pyridine ligands, or in resonance therewith, e.g. in isocyanide ligands C=N-R or as complexed central atoms
    • B01J31/1805—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes containing nitrogen, phosphorus, arsenic or antimony as complexing atoms, e.g. in pyridine ligands, or in resonance therewith, e.g. in isocyanide ligands C=N-R or as complexed central atoms the ligands containing nitrogen
    • B01J31/181—Cyclic ligands, including e.g. non-condensed polycyclic ligands, comprising at least one complexing nitrogen atom as ring member, e.g. pyridine
    • B01J31/1825—Ligands comprising condensed ring systems, e.g. acridine, carbazole
    • B01J31/183—Ligands comprising condensed ring systems, e.g. acridine, carbazole with more than one complexing nitrogen atom, e.g. phenanthroline
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/39—Photocatalytic properties
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/30—Treatment of water, waste water, or sewage by irradiation
    • C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/80—Type of catalytic reaction
    • B01D2255/802—Photocatalytic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/26—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof
    • C02F2103/28—Nature of the water, waste water, sewage or sludge to be treated from the processing of plants or parts thereof from the paper or cellulose industry
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/10—Photocatalysts
    • 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
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/30—Wastewater or sewage treatment systems using renewable energies
    • Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy

Definitions

  • the invention relates to volume-doped titanium dioxide composites, a process for their preparation and their use.
  • AOP advanced oxidation methods
  • Titanium dioxide and zinc oxide are the most widespread photocatalysts because they are inexpensive, non-polluting and reusable. Both have been successfully used to eliminate non-biodegradable pollutants from aqueous environments. In studies on the degradation of organic compounds significant reductions of the pollutants were detected in a short time. In many cases, a complete mineralization of the organic constituents was found. The use of photocatalysis for the decomposition of inorganic substances has also been reported. This toxic heavy metal compounds were converted into less toxic.
  • Titanium dioxide is recognized as currently the most efficient photocatalytic agent for solving environmental problems.
  • Titanium dioxide requires UV-A radiation with wavelengths less than about 385 nm to be photocatalytically active.
  • the energy of this light corresponds to the bandgap between its valence and conduction band. Therefore, at sea level only about 5% of solar radiation can be used to stimulate it.
  • the prior art has already proposed a photobleach for detergents.
  • An association between the action of the phthalocyanine and the TiO 2 was not established.
  • the state The technology corresponding catalysts are not very active.
  • the known catalysts have disadvantages, because they can convert only a small part (about 5%) of the solar spectrum into chemical energy.
  • WO 2004/089525 A2 describes the coating of titanium dioxide particles with zinc phthalocyanine in DMSO and subsequent drying of the surface-coated particles.
  • No. 5,238,581 A describes a catalytic process for reducing complexed cyanides in wastewater by, for example, phthalocyanine as catalyst, which can be adsorbed on a carrier material.
  • This support material may be selected from coal, silicates or aluminum compounds.
  • the object of the present invention is to provide new photochemical catalysts for photochemical processes and in particular for the decontamination of the environment.
  • the present invention provides volume-doped titanium dioxide composites containing zinc phthalocyanine.
  • the photosensitizer zinc phthalocyanine is distributed over the entire volume of titanium dioxide composites and not just at the surface.
  • the composites contain 0.5 to 20 wt .-%, in particular 1 to 10 wt .-% zinc phthalocyanine based on titanium dioxide.
  • the components according to the invention may also optionally contain further photosensitizers, in particular those with low solubility in aqueous media. In this sense, it is possible to use metallated phthalocyanines.
  • the photocatalytic efficiency of the compound (composite) according to the invention is significantly higher than previously titanium dioxide (both Anatas and Degussa ® P25) is superior.
  • P25 is the most widely prepared semiconductor photocatalyst known for its excellent properties for reducing a significant number of pollutants.
  • titanium dioxide with a photosensitizing dye of the present invention can absorb radiation and excite electron transfer in a wavelength range which can not be utilized by the pure photocatalyst. This results in a unique improvement in the photocatalyst activity.
  • the durability of the catalyst is increased, in which the dye is also localized in the volume and not only on the surface of the titanium dioxide particles. It is a combination of titanium dioxide and a photosensitizing dye that allows electron transfer to enhance the photocatalytic activity of titanium dioxide, as a wider wavelength range of light is available than in any of the known catalysts. Examples of usage are:
  • the combination produced in various proportions of dye and titanium dioxide, can be used as a heterogeneous catalyst (composite catalyst) for the purification of water (e.g., industrial effluents, etc.) and other fluids containing poorly or even non-biodegradable substances.
  • a heterogeneous catalyst composite catalyst for the purification of water (e.g., industrial effluents, etc.) and other fluids containing poorly or even non-biodegradable substances.
  • the composite catalyst according to the invention can also be used to remove pollutants from gases such as air (toxic compounds, odors).
  • the composite catalyst according to the invention can also be used for the photocatalytic cleaning of soiled surfaces (eg degradation of oil films on water or solid materials).
  • the composite catalyst of the invention can prevent their contamination as a coating on surfaces.
  • Another embodiment of the present invention relates to the preparation of the composites defined above. These are obtained by dissolving the photosensitizer in a solvent and then with a precursor of titanium dioxide, in particular titanium tetra alcoholate, the mixture stirred for a few hours, dried, added distilled water and then neutralized.
  • a precursor of titanium dioxide in particular titanium tetra alcoholate
  • the mixture thus obtained is allowed to rest, for example, for 24 hours at a constant temperature of about 70 0 C, after which the supernatant is removed after removal of water and then the precipitate is washed with distilled water, the salts, which in the process by Neutralization of the acid have formed, be removed. It is then dried, for example, at a constant temperature of 80 0 C, until complete evaporation of the liquid contained in the dry mass, in particular water and alcohol. Following this, a calcination may possibly follow.
  • Alternative aftertreatments include, for example, a rest followed by the mixing process with and without the addition of water or acid (in particular sulfuric acid) or alkali (in particular sodium hydroxide solution) and / or other solvents various constant or non-constant temperatures (especially 40 to 95 ° C, especially 60 to 80 0 C) for different periods of time (2 to 72 hours, especially 2 to 12 hours).
  • water or acid in particular sulfuric acid
  • alkali in particular sodium hydroxide solution
  • solvents various constant or non-constant temperatures (especially 40 to 95 ° C, especially 60 to 80 0 C) for different periods of time (2 to 72 hours, especially 2 to 12 hours).
  • Resting may be accompanied by evaporation (partial or dry) or non-evaporation.
  • a separation following the quiescent phase in the case of non-evaporation, for example by filtration or sedimentation, washing with water or acids (preferably sulfuric acid) / bases (preferably sodium hydroxide solution) for neutralization and / or with other solvents (including organic such as alcohols, in particular Ethanol) as well as the non-washing of the filter cake can also be carried out according to the invention.
  • acids preferably sulfuric acid
  • bases preferably sodium hydroxide solution
  • other solvents including organic such as alcohols, in particular Ethanol
  • the composites according to the invention can be prepared according to the following summary description:
  • the Synthesis of the titanium dioxides doped with photosensitizing dye by dissolving the dye (zinc phthalocyanine), for example, in an alcohol and / or polyhydric alcohol and / or an ether and / or a polyether, in particular methanol and / or ethanol and / or tetrahydrofuran) and an organic acid such as formic acid and / or a mineral acid such as sulfuric acid instead.
  • titanium tetraalcoholate in particular titanium tetraisopropylate
  • another titanium dioxide precursor is used as, in particular, alcoholic and / or ethereal solution for preparing the compound in one of its mixtures (1.0, 2.5, 5.0, 7.5; 10.0% m / m) was added slowly with vigorous stirring. Then, if necessary, the mixture is either stirred for several hours, allowed to stand in the air, dried and crushed, or distilled water is added with vigorous stirring, the acid is neutralized with sodium hydroxide, for example, in case a mineral acid is used, and the batch is allowed to stand for a few days , dried and crushed. If an organic acid is used, the acid may also preferably be evaporated instead of the neutralization, so that a salt-free catalyst is formed.
  • titanium tetraalcoholate in particular titanium tetraisopropylate
  • another titanium dioxide precursor is used as, in particular, alcoholic and / or ethereal solution for preparing the compound in one of its mixtures (
  • the compound is preferably calcined at 100 to 600 0 C, in particular at 300 to 600 0 C for several hours.
  • the calcination can also be carried out in a closed vessel under vacuum or under pressure in the presence of inert gas such as nitrogen or argon.
  • the titanium dioxide absorbs UV light below 385 nm. This results in an excess of electrons in the conduction band (e bc ) and holes in the valence band (h + bv ).
  • UV-A light (320-400 nm) was used. Similar experiments with solar radiation at a mean 50 W / m 2 (UV-A) but with a compound with 5% m / m photocatalyst led to a two fold faster degradation of a mixture of lignin fragments or lignosulfonate compared to P25 and two and a half times faster degradation in the Comparison to anatase (99.9%, Acros).
  • the photosensitizing dye enables the use of the solar spectrum to activate the oxide semiconductor.
  • a diffuse reflection spectrum shows that the dye absorbs very effectively above 500 nm, where the solar radiation reaches its maximum intensity.
  • volume-doped photocatalyst carries the same chromophore as the already proposed photocatalyst, comparable absorption and similar photocatalytic degradation properties can be expected. Incorporation of the chromophore into the catalyst volume also provides better protection against loss of activity due to bleeding and, because of the dye's isolation from high energy UV radiation, also provides greater protection against fading.
  • titanium dioxide makes larger surfaces accessible than, for example, P25.

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Abstract

The invention relates to volume-doped titanium dioxide composites, a method for production and use thereof.

Description

Volumendotierte Titandioxid-Komposite Volume-doped titanium dioxide composites
Gegenstand der Erfindung sind volumendotierte Titandioxid-Komposite, ein Verfahren zu ihrer Herstellung und ihre Verwendung.The invention relates to volume-doped titanium dioxide composites, a process for their preparation and their use.
Zur Verbesserung der Wirtschaftlichkeit von photokatalytischen Reaktionen sowohl zur Synthese von Chemikalien, als auch zum Abbau von Schadstoffen in Fluiden sind leistungsfähige Katalysatoren notwendig. Besonders bei Nutzung von Solarstrahlung muss der Katalysator über einen möglichst weiten Bereich des Sonnenspektrums aktiv sein.To improve the efficiency of photocatalytic reactions both for the synthesis of chemicals, as well as the degradation of pollutants in fluids powerful catalysts are necessary. Especially when using solar radiation, the catalyst must be active over as wide a range of the solar spectrum.
Unter den verschiedenen Technologien zur Lösung von Umweltpro¬ blemen sind die fortgeschrittenen Oxidationsmethoden (AOP) die derzeit leistungsfähigsten. Sie basieren auf der Erzeugung von Hydroxyl- radikalen als Oxidationsmittel. Im Gegensatz zu den traditionellen Reinigungsprozessen, bei denen die Umweltbelastung häufig nur verlagert wird, zielen die AOPs auf die vollständige Eliminierung der Schadstoffe aus der Umwelt ab.Among the various technologies for solving environmental problems are the advanced oxidation methods (AOP) which are currently the most efficient. They are based on the generation of hydroxyl radicals as oxidizing agents. Unlike traditional cleaning processes, where environmental pollution is often relocated, AOPs aim to completely eliminate environmental pollutants.
Halbleiteroxide werden als Katalysatoren in photochemischen Prozessen zur Dekontaminierung von Schadstoffen verwendet. Diese Prozesse werden sowohl durch solare als auch durch künstliche Strahlung angeregt. Titandioxid und Zinkoxid sind als Photokatalysatoren am weitesten verbreitet, da sie preisgünstig, nicht umweltgefährdend und wieder verwendbar sind. Beide wurden erfolgreich zur Eliminierung von biologisch nicht abbaubaren Schadstoffen aus wässrigen Umgebungen eingesetzt. In Studien zum Abbau organischer Verbindungen wurden bedeutende Reduktionen der Schadstoffe in kurzer Zeit nachgewiesen. In vielen Fällen wurde eine vollständige Mineralisierung der organischen Bestandteile festgestellt. Es wurde auch über den Einsatz der Photokatalyse zum Abbau anorganischer Stoffe berichtet. Dabei wurden toxische Schwermetallverbindungen in weniger toxische überführt.Semiconductor oxides are used as catalysts in photochemical processes for the decontamination of pollutants. These processes are stimulated by both solar and artificial radiation. Titanium dioxide and zinc oxide are the most widespread photocatalysts because they are inexpensive, non-polluting and reusable. Both have been successfully used to eliminate non-biodegradable pollutants from aqueous environments. In studies on the degradation of organic compounds significant reductions of the pollutants were detected in a short time. In many cases, a complete mineralization of the organic constituents was found. The use of photocatalysis for the decomposition of inorganic substances has also been reported. This toxic heavy metal compounds were converted into less toxic.
Titandioxid ist als derzeit effizientestes photokatalytisches Agens zur Behebung von Umweltproblemen anerkannt.Titanium dioxide is recognized as currently the most efficient photocatalytic agent for solving environmental problems.
Titandioxid benötigt UV-A-Strahlung mit Wellenlängen kleiner etwa 385 nm, um photokatalytisch aktiv zu sein. Die Energie dieses Lichts entspricht der Bandlücke zwischen seinem Valenz- und Leitungsband. Daher können auf Meereshöhe nur etwa 5% der solaren Strahlung zu seiner Anregung genutzt werden.Titanium dioxide requires UV-A radiation with wavelengths less than about 385 nm to be photocatalytically active. The energy of this light corresponds to the bandgap between its valence and conduction band. Therefore, at sea level only about 5% of solar radiation can be used to stimulate it.
Der Elektronentransfer von einem Farbstoff auf einen Halbleiter wurde ebenfalls intensiv untersucht, um Sonnenenergie effizienter nutzen zu können. Insbesondere wurde bereits die Adsorption von Zink- Phthalocyanin an der Oberfläche kommerziell erhältlicher Titandioxidqualitäten untersucht.The electron transfer from a dye to a semiconductor has also been intensively studied to make more efficient use of solar energy. In particular, the adsorption of zinc phthalocyanine on the surface of commercially available titanium dioxide grades has already been investigated.
Im Stand der Technik wurde bereits ein Photobleichmittel für Waschmittel vorgeschlagen. Ein Zusammenhang zwischen der Wirkung des Phthalocyanins und des Tiθ2 wurde nicht hergestellt. Dem Stand der Technik entsprechende Katalysatoren sind wenig aktiv. Besonders für eine solare Anwendung besitzen die bekannten Katalysatoren Nachteile, weil sie nur einen kleinen Teil (ca. 5%) des solaren Spektrums in chemische Energie umwandeln können.The prior art has already proposed a photobleach for detergents. An association between the action of the phthalocyanine and the TiO 2 was not established. The state The technology corresponding catalysts are not very active. Especially for a solar application, the known catalysts have disadvantages, because they can convert only a small part (about 5%) of the solar spectrum into chemical energy.
Ein bereits vorgeschlagener Photokatalysator, der durch Adsorption des Zink-Phthalocyanin an der Titandioxidoberfläche hergestellt wird, ist bezüglich seiner Haltbarkeit noch zu stark begrenzt.An already proposed photocatalyst, which is produced by adsorption of the zinc phthalocyanine on the titanium dioxide surface, is still too limited in its durability.
Exemplarisch werden im Folgenden einige bereits bekannte derartige Photokatalysatoren mit einer oberflächlichen Beschichtung aus Phthalocyanin auf Oxidpartikeln aufgeführt:By way of example, some already known such photocatalysts with a surface coating of phthalocyanine on oxide particles are listed below:
WO 2004/089525 A2 beschreibt die Beschichtung von Titandioxidpartikeln mit Zink-Phthalocyanin in DMSO und anschließender Trocknung der oberflächlich beschichteten Partikel.WO 2004/089525 A2 describes the coating of titanium dioxide particles with zinc phthalocyanine in DMSO and subsequent drying of the surface-coated particles.
US 4,520,072 A beschreibt die oberflächliche Beschichtung von Trägermaterialien mit photosensitiven Verbindungen.No. 4,520,072 A describes the superficial coating of support materials with photosensitive compounds.
US 5,238,581 A beschreibt ein katalytisches Verfahren zur Verminderung komplexierter Cyanide in Abwasser durch beispielsweise Phthalocyanin als Katalysator, welches auf einem Trägermaterial adsorbiert sein kann. Dies Trägermaterial kann ausgewählt sein aus Kohle, Silikaten oder auch Aluminiumverbindungen.No. 5,238,581 A describes a catalytic process for reducing complexed cyanides in wastewater by, for example, phthalocyanine as catalyst, which can be adsorbed on a carrier material. This support material may be selected from coal, silicates or aluminum compounds.
US 4,915,804 A beschreibt Titanate, die mit photosensitiven Verbindungen beschichtet sind. Phthalocyanine werden als besonders nachteilig erwähnt. US 4,806,514 A beschreibt Phthalocyanine in einer Polymermatrix, in der auch Oxidpartikel vorhanden sein können. Hierbei kommen die Phthalocyanine mit der Oberfläche der Oxidpartikel in Kontakt.US 4,915,804 A describes titanates which are coated with photosensitive compounds. Phthalocyanines are mentioned as particularly disadvantageous. No. 4,806,514 A describes phthalocyanines in a polymer matrix in which oxide particles may also be present. Here, the phthalocyanines come into contact with the surface of the oxide particles.
Die Aufgabe der vorliegenden Erfindung besteht in der Bereitstellung von neuen photochemischen Katalysatoren für photochemische Prozesse und insbesondere zur Dekontaminierung der Umwelt.The object of the present invention is to provide new photochemical catalysts for photochemical processes and in particular for the decontamination of the environment.
Gegenstand der vorliegenden Erfindung sind in einer ersten Ausführungsform volumendotierte Titandioxid-Komposite enthaltend Zink-Phthalocyanin.In a first embodiment, the present invention provides volume-doped titanium dioxide composites containing zinc phthalocyanine.
Im Gegensatz zum Stand der Technik ist der Photosensibilisator Zink- Phthalocyanin über das gesamte Volumen der Titandioxid-Komposite und nicht nur an der Oberfläche verteilt.In contrast to the prior art, the photosensitizer zinc phthalocyanine is distributed over the entire volume of titanium dioxide composites and not just at the surface.
Besonders bevorzugt im Sinne der vorliegenden Erfindung enthalten die Komposite 0,5 bis 20 Gew.-%, insbesondere 1 bis 10 Gew.-% Zink- Phthalocyanin bezogen auf Titandioxid.Particularly preferred according to the present invention, the composites contain 0.5 to 20 wt .-%, in particular 1 to 10 wt .-% zinc phthalocyanine based on titanium dioxide.
Neben dem Zink-Phthalocyanin können die erfindungsgemäßen Komponenten auch gegebenenfalls weitere Photosensibilisatoren, insbesondere solche mit geringer Löslichkeit in wässrigen Medien enthalten. In diesem Sinne ist es möglich metallierte Phthalocyanine einzusetzen.In addition to zinc phthalocyanine, the components according to the invention may also optionally contain further photosensitizers, in particular those with low solubility in aqueous media. In this sense, it is possible to use metallated phthalocyanines.
Es ist hervorzuheben, dass die photokatalytische Effizienz der erfindungsgemäßen Verbindung (Komposit) deutlich dem bisher untersuchten Titandioxid (sowohl Anatas als auch Degussa® P25) überlegen ist. P25 ist dabei der am weitest vorbereitete Halbleiterphotokatalysator und für seine exzellenten Eigenschaften zum Abbau einer beträchtlichen Anzahl von Schadstoffen bekannt.It should be emphasized that the photocatalytic efficiency of the compound (composite) according to the invention is significantly higher than previously titanium dioxide (both Anatas and Degussa ® P25) is superior. P25 is the most widely prepared semiconductor photocatalyst known for its excellent properties for reducing a significant number of pollutants.
Die erfindungemäße Kombination von Titandioxid mit einem photosensibilisierenden Farbstoff kann Strahlung absorbieren und einen Elektronentransfer anregen in einem Wellenlängenbereich, der von dem reinen Photokatalysator nicht genutzt werden kann. Daraus folgt eine einzigartige Verbesserung der Aktivität des Photokatalysators.The combination of titanium dioxide with a photosensitizing dye of the present invention can absorb radiation and excite electron transfer in a wavelength range which can not be utilized by the pure photocatalyst. This results in a unique improvement in the photocatalyst activity.
Insbesondere wird die Haltbarkeit des Katalysators erhöht, in dem der Farbstoff auch im Volumen und nicht nur auf der Oberfläche der Titandioxid partikel lokalisiert wird. Es handelt sich um eine Kombination von Titandioxid und einem photosensibilisierenden Farbstoff, die einen Elektronentransfer ermöglicht, so dass die photokatalytische Aktivität des Titandioxids verstärkt wird, da ein größerer Wellenlängenbereich des Lichtes nutzbar ist als bei allen bekannten Katalysatoren. Beispiele für eine Nutzung sind:In particular, the durability of the catalyst is increased, in which the dye is also localized in the volume and not only on the surface of the titanium dioxide particles. It is a combination of titanium dioxide and a photosensitizing dye that allows electron transfer to enhance the photocatalytic activity of titanium dioxide, as a wider wavelength range of light is available than in any of the known catalysts. Examples of usage are:
• Die Kombination, die in verschiedenen Verhältnissen von Farbstoff und Titandioxid hergestellt wird, kann als heterogener Katalysator (Komposit Katalysator) zur Reinigung von Wasser (z.B. Industrieabwässer etc.) und anderen Fluiden eingesetzt werden, die schlecht bis gar nicht biologisch abbaubare Substanzen enthalten.The combination, produced in various proportions of dye and titanium dioxide, can be used as a heterogeneous catalyst (composite catalyst) for the purification of water (e.g., industrial effluents, etc.) and other fluids containing poorly or even non-biodegradable substances.
• Der erfindungsgemäße Komposit-Katalysator kann auch zur Entfernung von Schadstoffen aus Gasen wie etwa Luft (toxische Verbindungen, Geruchsstoffe) verwendet werden. • Der erfindungsgemäße Komposit- Katalysator kann auch zur photokatalytischen Reinigung von verschmutzten Oberflächen dienen (z.B. Abbau von Ölfilmen auf Wasser oder festen Materialien).The composite catalyst according to the invention can also be used to remove pollutants from gases such as air (toxic compounds, odors). The composite catalyst according to the invention can also be used for the photocatalytic cleaning of soiled surfaces (eg degradation of oil films on water or solid materials).
• Der erfindungsgemäße Komposit-Katalysator kann als Beschichtung auf Oberflächen deren Verschmutzung verhindern.The composite catalyst of the invention can prevent their contamination as a coating on surfaces.
Eine weitere Ausführungsform der vorliegenden Erfindung betrifft die Herstellung der oben definierten Komposite. Diese werden dadurch erhalten, dass man den Photosensibilisator in einem Lösungsmittel löst und anschließend mit einem Precursor (Vorläufer) von Titandioxid, insbesondere Titantetraalkoholat die Mischung einige Stunden rührt, trocknet, destilliertes Wasser zusetzt und anschließend neutralisiert.Another embodiment of the present invention relates to the preparation of the composites defined above. These are obtained by dissolving the photosensitizer in a solvent and then with a precursor of titanium dioxide, in particular titanium tetra alcoholate, the mixture stirred for a few hours, dried, added distilled water and then neutralized.
Im Anschluss daran wird die so erhaltene Mischung beispielsweise 24 Stunden bei einer konstanten Temperatur von etwa 70 0C ruhen gelassen, wonach nach Abtrennen des Überstandes Wasser entfernt wird und anschließend der Niederschlag mit destilliertem Wasser gewaschen wird, wobei die Salze, die sich im Verfahren durch Neutralisation der Säure gebildet haben, entfernt werden. Anschließend trocknet man beispielsweise bei einer konstanten Temperatur von 80 0C, und zwar bis zur vollständigen Verdampfung der in der trockenen Masse enthaltenen Flüssigkeit, insbesondere Wasser und Alkohol. Im Anschluss daran kann sich gegebenenfalls eine Calcinierung anschließen.Subsequently, the mixture thus obtained is allowed to rest, for example, for 24 hours at a constant temperature of about 70 0 C, after which the supernatant is removed after removal of water and then the precipitate is washed with distilled water, the salts, which in the process by Neutralization of the acid have formed, be removed. It is then dried, for example, at a constant temperature of 80 0 C, until complete evaporation of the liquid contained in the dry mass, in particular water and alcohol. Following this, a calcination may possibly follow.
Alternative Nachbehandlungen umfassen beispielsweise einen sich dem Mischvorgang anschließendes Ruhen lassen mit und ohne Zusatz von Wasser oder Säure (insbesondere Schwefelsäure) oder Lauge (insbesondere Natronlauge) und/oder anderen Lösungsmitteln bei verschiedenen konstanten oder nicht-konstanten Temperaturen (vor allem 40 bis 95°C, insbesondere 60 bis 800C) für verschiedene Zeitdauern (2 bis 72h, insbesondere 2 bis 12h).Alternative aftertreatments include, for example, a rest followed by the mixing process with and without the addition of water or acid (in particular sulfuric acid) or alkali (in particular sodium hydroxide solution) and / or other solvents various constant or non-constant temperatures (especially 40 to 95 ° C, especially 60 to 80 0 C) for different periods of time (2 to 72 hours, especially 2 to 12 hours).
Das Ruhen lassen kann mit Eindampfen (partiell oder zur Trockene) oder Nicht-Eindampfen einhergehen.Resting may be accompanied by evaporation (partial or dry) or non-evaporation.
Ein sich der Ruhephase im Falle des Nicht-Eindampfens anschließendes Separieren, beispielsweise, durch Filtration oder Sedimentation, Waschen mit Wasser oder Säuren (bevorzugt Schwefelsäure)/Laugen (bevorzugt Natronlauge) zur Neutralisation und/oder mit anderen Lösungsmitteln (auch organischen wie Alkoholen, insbesondere Ethanol) sowie auch das Nicht-Waschen des Filterkuchens kann erfindungsgemäß ebenfalls durchgeführt werden.A separation following the quiescent phase in the case of non-evaporation, for example by filtration or sedimentation, washing with water or acids (preferably sulfuric acid) / bases (preferably sodium hydroxide solution) for neutralization and / or with other solvents (including organic such as alcohols, in particular Ethanol) as well as the non-washing of the filter cake can also be carried out according to the invention.
Ein sich der Ruhephase im Falle des Eindampfens anschließendes Waschen mit Wasser oder Säuren (bevorzugt Schwefelsäure)/Laugen (bevorzugt Natronlauge) zur Neutralisation und/oder mit anderen Lösungsmitteln (auch organischen wie Alkoholen, insbesondere Ethanol) sowie auch das Nicht-Waschen des Rückstandes ist ebenfalls Gegenstand der vorliegenden Erfindung.One of the rest phase in the case of evaporation subsequent washing with water or acids (preferably sulfuric acid) / bases (preferably sodium hydroxide) for neutralization and / or with other solvents (including organic such as alcohols, especially ethanol) and also the non-washing of the residue also the subject of the present invention.
Eine Calcinierung im unten beschriebenen Temperaturbereich für verschiedene Zeitdauern im Anschluss an die Vorbehandlungen sowie die Nicht-Calicinierung sind ebenfalls Gegenstand der vorliegenden Erfindung.A calcination in the temperature range described below for various periods following the pretreatments and the non-calicination are also the subject of the present invention.
Allgemein können die erfindungsgemäßen Komposite nach der folgenden zusammenfassenden Beschreibung hergestellt werden: Die Synthese des mit photosensibilisierendem Farbstoff volumendotierten Titandioxides findet durch Auflösen des Farbstoffs (Zink-Phthalocyanin) beispielsweise in einem Alkohol und/oder Polyalkohol und/oder einem Ether und/oder einem Polyether, insbesondere Methanol und/oder Ethanol und/oder Tetra hydrofu ran ) sowie eine organische Säure wie Ameisensäure und/oder eine Mineralsäure wie Schwefelsäure statt. Danach wird die erforderliche Menge von Titantetraalkoholat (insbesondere Titantetraisopropylat) oder eines anderen Titandioxid- Vorläufers als insbesondere alkoholische und/oder etherische Lösung zur Herstellung der Verbindung in einer ihrer Mischungen (1,0; 2,5; 5,0; 7,5; 10,0 % m/m) langsam unter starkem Rühren zugegeben. Danach wird die Mischung gegebenenfalls entweder einige Stunden gerührt, an der Luft stehen gelassen, getrocknet und zerkleinert oder unter heftigem Rühren destilliertes Wasser zugesetzt, die Säure beispielsweise mit Natriumhydroxid neutralisiert für den Fall, dass eine Mineralsäure eingesetzt wird, und der Ansatz einige Tage stehen gelassen, getrocknet und zerkleinert. Wird eine organische Säure eingesetzt, so kann die Säure auch statt der Neutralisation bevorzugt verdampft werden, so dass ein salzfreier Katalysator entsteht.In general, the composites according to the invention can be prepared according to the following summary description: The Synthesis of the titanium dioxides doped with photosensitizing dye by dissolving the dye (zinc phthalocyanine), for example, in an alcohol and / or polyhydric alcohol and / or an ether and / or a polyether, in particular methanol and / or ethanol and / or tetrahydrofuran) and an organic acid such as formic acid and / or a mineral acid such as sulfuric acid instead. Thereafter, the required amount of titanium tetraalcoholate (in particular titanium tetraisopropylate) or another titanium dioxide precursor is used as, in particular, alcoholic and / or ethereal solution for preparing the compound in one of its mixtures (1.0, 2.5, 5.0, 7.5; 10.0% m / m) was added slowly with vigorous stirring. Then, if necessary, the mixture is either stirred for several hours, allowed to stand in the air, dried and crushed, or distilled water is added with vigorous stirring, the acid is neutralized with sodium hydroxide, for example, in case a mineral acid is used, and the batch is allowed to stand for a few days , dried and crushed. If an organic acid is used, the acid may also preferably be evaporated instead of the neutralization, so that a salt-free catalyst is formed.
Anschließend wird die Verbindung vorzugsweise bei 100 bis 600 0C, insbesondere bei 300 bis 600 0C mehrere Stunden calciniert. Vorzugsweise kann die Calcinierung auch in einem geschlossenen Gefäß im Vakuum oder unter Druck auch in Gegenwart von Inertgas wie beispielsweise Stickstoff oder Argon erfolgen.Subsequently, the compound is preferably calcined at 100 to 600 0 C, in particular at 300 to 600 0 C for several hours. Preferably, the calcination can also be carried out in a closed vessel under vacuum or under pressure in the presence of inert gas such as nitrogen or argon.
Das Titandioxid absorbiert UV-Licht unterhalb 385 nm. Dadurch entsteht ein Elektronenüberschuss im Leitungsband (e bc) und Löcher im Valenzband (h+bv).
Figure imgf000010_0001
The titanium dioxide absorbs UV light below 385 nm. This results in an excess of electrons in the conduction band (e bc ) and holes in the valence band (h + bv ).
Figure imgf000010_0001
Diese besitzen für die Wirkung der Photokatalyse mit Halbleitern wichtigen Prozesse eine niedrige Quantenausbeute (φ » 0,05), wahrscheinlich aufgrund der effizienten Rekombination der Löcher des Valenzbandes und Elektronen des Leitungsbandes im Halbleiter.These have important low-quantum efficiency (φ »0.05) for the effect of photocatalysis with semiconductors, probably due to the efficient recombination of the holes of the valence band and electrons of the conduction band in the semiconductor.
Die photokatalytische Wirkung ist das Resultat der Wanderung der Löcher und der Elektronen zur Oberfläche des Katalysators wo sie wie folgt reagieren:The photocatalytic effect is the result of migration of holes and electrons to the surface of the catalyst where they react as follows:
h+bv +OrT→#OHh + bv + OrT → # OH
θ bc +O2 → O2 * θ bc + O 2 → O 2 *
2O2 * + 2H+ →2#OH + O2 2O 2 * + 2H + → 2 # OH + O 2
Es entstehen intermediär freie Radikale, die die vorhandenen Schadstoffe abbauen. Durch Zusatz von Wasserstoffperoxid steigt die Effizient des photokatalytischen Prozesses, da die Konzentration an freien Radikalen erhöht wird.Intermediate free radicals are formed, which degrade the existing pollutants. The addition of hydrogen peroxide increases the efficiency of the photocatalytic process by increasing the concentration of free radicals.
e"bc +H2O2VOH + "OH Durch volumendotierte Assoziation des photosensibilisierenden Farbstoffs an den oxidischen Halbleiter konnten durch die Anregung des Farbstoffs Anteile des sichtbaren Spektrums für den photokatalytischen Prozess benutzt werden. Durch die Anregung des Farbstoffs, werden Elektronen ins Leitungsband des oxidischen Halbleiters gehoben, wodurch die Effizienz des photokatalytischen Prozesses steigt.e " bc + H 2 O 2 VOH + " OH By volume-doped association of the photosensitizing dye with the oxide semiconductor, it was possible to use portions of the visible spectrum for the photocatalytic process by exciting the dye. By the excitation of the dye, electrons are lifted into the conduction band of the oxide semiconductor, whereby the efficiency of the photocatalytic process increases.
Bei der vorgeschlagenen Verwendung von oberflächendotierten Kompositen aus adsorbiertem Zink-Phthalocyanin konnte eine Erhöhung der Quantenausbeute, mit der Menge der Hydroxyl radikale, nachgewiesen werden. Erfindungsgemäß wird eine weitere Verbesserung angenommen.In the proposed use of surface doped composites of adsorbed zinc phthalocyanine, an increase in the quantum yield, with the amount of hydroxyl radicals, could be detected. According to the invention, a further improvement is assumed.
Bei Untersuchungen im Labormaßstab wurde ein Anstieg der Effizienz eines Abbauprozesses von organischen Substanzen in Papier- und Zelluloseabwasser beobachtet.In laboratory scale studies, an increase in the efficiency of a decomposition process of organic substances in paper and cellulose was observed.
Für diese Reaktion wurde UV-A-Licht (320-400 nm) benutzt. Ähnliche Experimente mit Solarstrahlung mit mittleren 50 W/m2 (UV-A) jedoch mit einer Verbindung mit 5 % m/m Photokatalysator führten zu einem zweifach schnelleren Abbau einer Mischung von Ligninfragmenten oder Lignosulfonat im Vergleich zu P25 und zu einem zweieinhalbfach schnelleren Abbau im Vergleich zu Anatas (99,9 %, Acros).For this reaction UV-A light (320-400 nm) was used. Similar experiments with solar radiation at a mean 50 W / m 2 (UV-A) but with a compound with 5% m / m photocatalyst led to a two fold faster degradation of a mixture of lignin fragments or lignosulfonate compared to P25 and two and a half times faster degradation in the Comparison to anatase (99.9%, Acros).
Die Erklärung dafür ist, dass der photosensibilisierende Farbstoff die Verwendung des solaren Spektrums zur Aktivierung des oxidischen Halbleiters ermöglicht. Ein diffuses Reflexionsspektrum zeigt, dass der Farbstoff sehr effektiv oberhalb 500 nm absorbiert, wo die Solarstrahlung ihre maximale Intensität erreicht.The explanation for this is that the photosensitizing dye enables the use of the solar spectrum to activate the oxide semiconductor. A diffuse reflection spectrum shows that the dye absorbs very effectively above 500 nm, where the solar radiation reaches its maximum intensity.
Da der volumendotierte Photokatalysator den gleichen Chromophor wie der bereits vorgeschlagene Photokatalysator trägt, sind jeweils vergleichbare Absorptions- und ähnliche photokatalytische Abbaueigenschaften zu erwarten. Die Inkorporation des Chromophors in das Katalysatorvolumen bietet darüber hinaus besseren Schutz vor Aktivitätsverlusten aufgrund von Ausbluten und wegen der Isolierung des Farbstoffs vor energiereicher UV-Strahlung auch einen stärkeren Schutz vor Ausbleichen.Since the volume-doped photocatalyst carries the same chromophore as the already proposed photocatalyst, comparable absorption and similar photocatalytic degradation properties can be expected. Incorporation of the chromophore into the catalyst volume also provides better protection against loss of activity due to bleeding and, because of the dye's isolation from high energy UV radiation, also provides greater protection against fading.
Durch die erfindungsgemäße Synthese des Titandioxides sind größere Oberflächen als beispielsweise beim P25 zugänglich. The synthesis of titanium dioxide according to the invention makes larger surfaces accessible than, for example, P25.

Claims

Patentansprüche: claims:
1. Volumendotierte Titandioxid-Komposite, enthaltend Zink- Phthalocyanin.1. Volume-doped titanium dioxide composites containing zinc phthalocyanine.
2. Komposite nach Anspruch 1, dadurch gekennzeichnet, dass die Komposite 0,5 bis 20 Gew.-%, insbesondere 1 bis 10 Gew.-% Zink- Phthalocyanin, bezogen auf Titandioxid, enthalten.2. A composite according to claim 1, characterized in that the composites 0.5 to 20 wt .-%, in particular 1 to 10 wt .-% zinc phthalocyanine, based on titanium dioxide.
3. Komposite nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass diese weitere Photosensibilisatoren enthalten.3. A composite according to claim 1 or 2, characterized in that they contain further photosensitizers.
4. Verfahren zur Herstellung von Kompositen nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass man den Photosensibilisator in einem Lösungsmittel löst und anschließend einen Titandioxidprecursor, insbesondere Titantetraalkoholat zugibt, die Mischung einige Stunden rührt, trocknet, destilliertes Wasser zusetzt und anschließend neutralisiert.4. A process for the preparation of composites according to any one of claims 1 to 3, characterized in that dissolving the photosensitizer in a solvent and then a Titandioxidprecursor, especially Titantetraalkoholat admits, the mixture stirred for a few hours, dried, added distilled water and then neutralized.
5. Verwendung der Titandioxid-Komposite nach einem der Ansprüche 1 bis 4 in photokatalytischen Verfahren, wobei die Komposite in Form von wässrigen Suspensionen verwendet werden, die mit einem zu behandelnden Ausfluss vereinigt werden.5. Use of the titanium dioxide composites according to one of claims 1 to 4 in photocatalytic processes, wherein the composites are used in the form of aqueous suspensions, which are combined with an effluent to be treated.
6. Verwendung der Titandioxid-Komposite nach einem der Ansprüche 1 bis 4, wobei die Komposite in einer Form, in der sie an innere Kontaktoberflächen von photochemischen Reaktoren fixiert sind, für die Behandlung sowohl flüssiger als auch gasförmiger Ausflüsse verwendet werden. 6. Use of the titanium dioxide composites according to one of claims 1 to 4, wherein the composites are used in a form in which they are fixed to inner contact surfaces of photochemical reactors, for the treatment of both liquid and gaseous effluents.
7. Verwendung der Titandioxid-Komposite nach Anspruch 6 in photokatalytischen Verfahren, wobei der Katalysator an einer Oberfläche entweder durch Abscheiden auf derselben oder durch Reaktion mit einer Oberfläche, insbesondere durch Derivatisierung, fixiert ist.7. Use of the titanium dioxide composites according to claim 6 in photocatalytic processes, wherein the catalyst is fixed to a surface either by deposition on the same or by reaction with a surface, in particular by derivatization.
8. Verwendung der Titandioxid-Komposite nach einem der Ansprüche 1 bis 6 in photokatalytischen Verfahren, wobei die Komposite in wässrigen Suspensionen verwendet werden, die in Reaktoren vom Typ CPC (Compound Parabolic Collector) verwendet werden, wobei sie unter starkem Rühren zu den flüssigen Ausflüssen, die behandelt werden sollen, gegeben werden, und das Rühren während der gesamten Zeitspanne, in der die Photokatalyse erfolgt, beibehalten wird.8. Use of the titanium dioxide composites according to any one of claims 1 to 6 in photocatalytic processes, wherein the composites are used in aqueous suspensions used in CPC (Compound Parabolic Collector) type reactors, wherein they with vigorous stirring to the liquid effluents which are to be treated, and stirring is maintained throughout the period of photocatalysis.
9. Verwendung der Titandioxid-Komposite nach einem der Ansprüche 1 bis 8 in photokatalytischen Verfahren zur Dekontaminierung von Abwässern und zum Entfernen von Gerüchen der Umgebung dienen, insbesondere in Form der heterogenen Photokatalyse. 9. Use of the titanium dioxide composites according to one of claims 1 to 8 in photocatalytic processes for the decontamination of waste water and for removing odors of the environment serve, in particular in the form of heterogeneous photocatalysis.
PCT/EP2005/055583 2004-11-04 2005-10-26 Volume-doped titanium dioxide composites WO2006048400A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4806514A (en) * 1986-10-02 1989-02-21 Canadian Patents And Development Limited -Societe Canadienne Des Brevets Et D'exploitation Limitee Composite photocatalyst for refractory waste degradation
WO2004089525A2 (en) * 2003-04-11 2004-10-21 Conselho Nacional De Desenvolvimento Científico E Tecnológico - Cnpq Composites of zinc phthalocyanine and titanium oxide, for use in photocatalytical processes, and method for their obtention

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4806514A (en) * 1986-10-02 1989-02-21 Canadian Patents And Development Limited -Societe Canadienne Des Brevets Et D'exploitation Limitee Composite photocatalyst for refractory waste degradation
WO2004089525A2 (en) * 2003-04-11 2004-10-21 Conselho Nacional De Desenvolvimento Científico E Tecnológico - Cnpq Composites of zinc phthalocyanine and titanium oxide, for use in photocatalytical processes, and method for their obtention

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