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WO2014008953A1 - Photocatalytically active material for purifying air - Google Patents

Photocatalytically active material for purifying air

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Publication number
WO2014008953A1
WO2014008953A1 PCT/EP2012/065968 EP2012065968W WO2014008953A1 WO 2014008953 A1 WO2014008953 A1 WO 2014008953A1 EP 2012065968 W EP2012065968 W EP 2012065968W WO 2014008953 A1 WO2014008953 A1 WO 2014008953A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
photocatalyst
preferably
nm
light
material
Prior art date
Application number
PCT/EP2012/065968
Other languages
German (de)
French (fr)
Inventor
Thomas RETTENMOSER
Original Assignee
Anlarop Development Ag
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

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D49/00Separating dispersed particles from gases, air or vapours by other methods
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2255/00Catalysts
    • B01D2255/20Metals or compounds thereof
    • B01D2255/207Transition metals
    • B01D2255/20792Zinc
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2255/00Catalysts
    • B01D2255/20Metals or compounds thereof
    • B01D2255/209Other metals
    • B01D2255/2094Tin
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2255/00Catalysts
    • B01D2255/80Type of catalytic reaction
    • B01D2255/804Enzymatic
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2259/00Type of treatment
    • B01D2259/45Gas separation or purification devices adapted for specific applications
    • B01D2259/4508Gas separation or purification devices adapted for specific applications for cleaning air in buildings

Abstract

The invention relates to a method for the fine dust reduction using a photocatalyst and to a photocatalyst which is also active in the absence of UV light.

Description

Photocatalytic active material for air purification Description

The invention relates to a method for reducing fine dust by using a photocatalyst and a photocatalyst that is active even in the absence of UV light

Photocatalysts are excited in a photo-assisted catalytic reaction. This is for example to be used to generate on the surface of photocatalysts oxygen radicals, which in turn oxidize pollutants and thus make harmless can. A known photocatalytically active material is titanium dioxide (Ti0 2). For the excitation of titanium dioxide ultraviolet light is necessary.

An object of the present invention is to use photocatalytic effects for new applications and also provide new photocatalysts that are photocatalytically active even in the absence of UV light.

This object is inventively achieved by a method for reducing fine dust, which is characterized in that fine dust is separated from a gaseous medium by means of a photocatalytic material.

In particular, the invention relates to a method for reducing fine dust, which is characterized in that fine dust is separated from a gaseous medium by means of a photocatalytic material in daylight.

In particular, the invention relates to a method for reducing fine dust, which is characterized in that fine dust is separated from a gaseous medium by means of a photocatalytic material with no UV light.

According to the invention it has been found that by use of the photo-assisted catalytic reaction of photocatalytic materials is an electrostatic attraction of fine dust, which can thus be separated from gaseous media, in particular air. In this case, the photocatalytic material is displaced by the action of light of a suitable wavelength to an excited state catalyst. In this case, to maintain the reaction continued light exposure is required.

Photocatalytic material is referred to herein as photocatalytically active material.

The present invention can be used photocatalytic materials preferably include a photocatalyst, and optionally other materials such as binders. The photocatalyst may also be referred to as a photocatalytically-active substance, preferably has semiconductor characteristics. In a photocatalytically active semiconductor, electrons can be shifted to a higher energy state by excitation by light photons. Is the energy of the incident photon is sufficiently large, an electron from an energy state, for example, from an energetic ground state change at room temperature in the energy state of the conduction band. a defect electron or hole, thus a positive charge carriers generated at the original Steep the electron (negative charge carriers). At this point, a neighboring electron can move. In this process again positive hole is created, etc. As a result, the positive and negative charge carriers spread and can diffuse to the surface of the material. There is now specific charge distributions emerge. These charge distributions induce an electrostatic attraction, through which particulate matter may be separated from air. This effect was first observed by the inventors of the present application. More particularly, the present invention can be deposited on the photocatalytically active surface particulate matter through the existing charge distributions.

As far as it is a material in which a photocatalyst is that even on irradiation with visible light, ie in particular in the absence of UV light, is active, the charge distributions arise even without irradiation of UV light. Such materials may thus also for fine dust reduction in indoors, for example, in residential interiors or car interiors, be used where no photo-assisted catalytic reaction occurs when using conventional photocatalysts such as titanium dioxide because of the absence of UV radiation

The process can be carried out in daylight. In particular, it is carried out in daylight without additional UV light. In a preferred embodiment, the method in daylight with a diminished proportion of UV light, in particular with an at least 20%, more preferably at least 30%, even more preferably at least 50% and especially at least 80%, most preferably at least 90% attenuated is proportion of light of wavelengths of <350 nm, preferably <380 nm, especially <390 nm performed. An example of such a preferred embodiment is to carry out indoors, in which the natural light must pass first through glass, for example window glass, which has only a partial transmission of light in the UV range, in a preferred embodiment, the method in daylight will no UV light components performed. This example, when sunlight passes through thicker glass and therefore the UV light component is completely separated. However, the method of the invention can also be carried out in artificial light, in particular artificial light with a wavelength of 380 nm to 800 nm, in particular from 400 to 700 nm. The inventive method may in particular also be carried out in environments where irradiated no additional UV light is, particularly in environments where no UV light is present. Thus, the method according to the invention particularly in the absence of light having a wavelength of <400 nm can, especially <380 nm can be performed even more preferably <350 nm.

According to the invention preferably comprises the photocatalyst, at least one of the elements Sn, Zn, Bi, Ga, Ge, In, Ta, Ti, V, W, Sb or ΤΊ, in particular at least one of the elements Sn, Zn, Ta, Bi, In, V, W, Sb, Ge, Ga, TI and / or titanium, and more preferably Sn and / or Zn.

In a preferred embodiment, the photocatalyst comprises Sn. In a further preferred Ausführungsförm the photocatalyst comprises Zn. In yet another preferred embodiment, the photocatalyst comprises Sn and Zn.

In the photocatalyst, the elements are preferably in the form of compounds having semiconductor characteristics, for example as oxides. More preferably, the photocatalyst tin oxide (Sn0 2) and / or zinc oxide (ZnO).

A preferred mixture according to the invention as a photocatalyst material is Sn0. 2 Sn0 2 has an energy band gap of 3.5 to 3.7 eV corresponding to a wavelength range of 354-335 nm.

SnO has an energetic laden * band gap of about 2.9 eV are excited corresponding to a wavelength of 428 nm. Thus, such a Sn0 2 by blue light in the electromagnetic spectrum of visible light.

A further preferred employed as a photocatalyst material is ZnO. 5 ZnO has a band gap energy of about 3.37 eV corresponding to a wavelength of 368 nm.

10-10: 1, more preferably from 1: In a particularly preferred embodiment, a mixture of Sn0 2 and ZnO is used as a photocatalyst, in particular in einemo weight ratio of 1 3 to 3: 1st

In order to increase the usability of the photocatalysts in the process of the invention further, preferably, the band gaps of the active particles used be reduced

5

According to the invention it is therefore preferred to use a photocatalyst which is doped with one or more elements, in particular selected from Co, C, N, P, S or H. a photocatalyst is preferably used, which is preferably doped with Co, C and / or N at meisteno with Co. On doping impurity atoms are incorporated into the molecular structure of the photocatalyst. By doping the band gap, and thus the activation energy is reduced.

Particularly preferred according to the invention is used as a photocatalyst with Co5 doped ZnO and / or Sn0 2, in particular with co-doped ZnO. The weight ratio of Zn: Co is preferably from 8: 1 to 15: 1, especially from 9: 1 to 11: 1 and even more preferably from 9.5: 1 to 10.5: 1. It has been found according to the invention, that Co is incorporated into the crystal structure of ZnO. In particular, about 100 nm could insbesondereo doped ZnO photocatalysts having particle sizes in a range of about 50 nm to 1.5 pm, be prepared to 1.2 pm. loaded with Co ZnO has energy band gaps at about 1, 8 eV and 2.7 eV, corresponding to a wavelength of 690 nm or 460 nm. Due to the displacement of the necessary activation energy in the visible wavelength range, these materials can as a photocatalyst also upon irradiation with light can be used without any UV component.

Doped photocatalysts can be obtained for example by wet chemical or thermal methods.

In a further preferred embodiment, the photocatalyst with one or more elements, in particular selected from Pb, Au, Ag, Pt, Al, Cu, Sb, Mo, Cd, preferably selected from Au, Pt, Ag, Sb, Fe, Al, Cd, Cu or Pb loaded. Most preferred is a charge of Au and / or Pt. Particularly preferably, a loading of nanoparticles, in particular with nanoparticles that have a mean particle size of <10 nm, in particular <5 nm. In a particularly preferred embodiment, a loading with Au and / or R nanoparticles which have an average particle size -S auweisen 10 nm, in particular 5 s nm. At a loading smaller particles are caused by surface effects in a stable contact with larger particles by a loading, the bandgap and thus the activation energy of the active substance is decreased. In another preferred embodiment, different particles and / or different particle sizes are mixed for the photocatalyst. Preferably, for example, the mixture of ZnO, and Sn0 2. Furthermore, the same or different materials are preferably used in various particle sizes, for example in mixtures of particle sizes of <50 nm, in particle sizes of 50 to <150 nm and in particle sizes of 150 to 300 nm. It has been found that the particle size has an influence on the bandgap , Such small particles are particularly preferred. On the other hand, larger particles offer more potential attachment surface for fine dust. Thus, a mixture of different particle sizes is put to use according to the invention preferably

In a particularly preferred embodiment, the photocatalytic material used in the invention comprises

(I) a photocatalyst, and

(Ii) a binder.

The photocatalyst is preferably used in the form of small particles. Preferably, the photocatalytic material has a particle size of έ 1000 nm, more preferably £ 500 nm, even more preferably .s 300 nm, most preferably 150 nm and £ £ in particular 50 nm. With each particle size, the average particle diameter is herein, unless otherwise indicated, is meant.

Be particularly suitable silanes here have been placed as a binder. Particularly suitable are tetra-alkoxysilanes and (TEOS) in the specific Tetra-Ethyl-Ortho-silicates. The silanes preferably have a SiCVAnteil from 5 to 70 mol%, preferably from 10 to 50 mol% and especially from 15 to 30 mol% on.

in particular primary, secondary and tertiary alcohols and water and mixtures as a solvent, for example, for applying the photocatalytic material to a substrate are preferably alcohols thereof. Particularly preferred are primary alcohols, especially methanol, ethanol or propanol.

The measures provided for applying the photocatalytic material to a substrate compositions comprise further preferably surfactants. Such surfactants prevent agglomeration of the active particles so that the composition can be applied for example by spraying. Preferably, the process according to the invention in light is performed at a wavelength of 400 nm to 800 nm.

In a particularly preferred embodiment the inventive method for particulate matter reduction is carried out in an open system. An open system is especially characterized in that the normal air circulation is sufficient. The photocatalytic coatings come of it out with little to no UV light portion. Other requirements that must be met by an open system, are harmful to health of the coating as well as abrasion resistance.

In particular, an open system must be supplied to any external power and there is no force air streams, such that, in the case of closed systems, such as air conditioning. In closed systems are the photocatalytically active surfaces in the interior of a device. The pollutant-laden atmosphere, for example gases or bioaerosols are passed by forced air at these surfaces. The placement of the surfaces inside the machine in closed systems is there the advantage that they can be irradiated with a strong, physiologically harmful UV light. Such exposure is inventively but just not necessary. In summary it can be stated that the invention preferred open coating systems in contrast to conventional closed systems require no forced air flow and no irradiation with harmful to humans wavelengths and / or intensities of electromagnetic radiation.

By the present invention observed effect fine dust may be removed from gaseous media, in particular air. For particulate matter, these are particularly μιτι to particles present in air in limbo, so particular to particles having a mean particle diameter of £ 50th

Preferably, the particulate matter comprises particles having a size of 40 -S μπι on. According to the invention but also fine dusts having a particle size of <350 nm and ultra fine dust particles can be separated off with a particle size -S 100 nm. Especially with fine dust having a mean particle diameter of 100 nm £ excellent results could be obtained. Under fine pollen grains were understood according to the invention but which could also be successfully separated from air. Pollen grains typically have a mean particle diameter of from 10 pm to 30 pm.

the photocatalytic material is preferred for the inventive method applied to a substrate, which is then brought into contact with the gaseous medium. Suitable substrates include glass, plastic, textile structures, masonry, concrete, metal, ceramics, wood and / or composite materials. Particular preference is used as ground glass. By coating of glass sheets on the inside of a building or vehicle with a photocatalytic material which is active even without UV light, fine dust may be separated continuously and without further measures. The photocatalytic coatings are preferably indoors, such as private homes, public buildings, hospitals, schools, etc., or in vehicles such as buses, passenger compartments of cars and trucks, ships and aviation witnesses used.

The application of the photocatalytic material to the substrate can be carried out by conventional methods, for example by spraying, rolling, painting, spraying, dip coating, or vapor deposition. The present invention further comprises a photocatalyst which is active without UV light. The photocatalyst comprises one or more elements selected from Sn, Zn, Ta, Bi, In, V, W, Sb, Ge, Ga, Tl and / or Ti, in particular Sn and / or Zn. Particularly preferred is a photocatalyst which Sn0 2, ZnO or mixtures thereof. Particularly preferred is a photocatalyst, P, S or H is doped with one or more elements selected from Co, C, N. Particularly preferred is a photocatalyst which is most preferably doped with Co, C and / or N Co.

In a particularly preferred embodiment, the photocatalyst according to the invention with co-doped ZnO has. The weight ratio of Zn: Co is preferably from 8: 1 to 12: 1, particularly 9: 1 to 11: 1st

be instead of or in addition to the doping elements, the photocatalyst of the invention may with one or more elements, in particular selected from Au, Ag, Pt, Al, Cu, Sb, Mo, or Cd loaded. Most preferred is a charge of Au and / or Pt.

Particularly preferred is a photocatalytic material comprising such a photocatalyst and a binder, wherein the binder is selected from silanes. Preferably, the binder tetra- alkoxysilanes and especially tetra-ethyl-ortho-silicate comprises (TEOS). The S1O2- proportion of the silane is preferably 5 to 70 mol%, preferably 10 to 50 mol% and in particular 15 to 30 mol%. in a particularly favorable embodiment of the method for reducing fine dust from air fine dust is separated from air by means of an applied on glass photocatalytic material without UV light. For this application, the form of the photocatalyst preferably has particle sizes of less than 300 nm to be transparent to the human eye. The invention is further illustrated by the attached figures and the following examples.

1 shows XRD analysis of SnQrProben.

2 shows XRD analyzes of ZnO samples.

3 shows an XRD measurement of Co-doped ZnO. Clearly, the incorporation of Co in the crystal structure of ZnO can be seen.

Figure 4 shows a scanning electron microscopy image of Co-doped ZnO particles.

Examples

example 1

Co-doped ZnO

With two different methods, namely wet-chemical and thermal, ZnO doped with Co. Zn the proportion by weight: Co was in each case 10: 1. agent energiedisperser X-ray analysis (EDX), it was found that the mass ratio of the elements in the doped photocatalyst value continuously so Zn mass ratio of the reactants, a ratio: Co = 10: 1, corresponded. By UV / Vis-NIR analysis it was found that with co-doped ZnO having at least two active bandgap at about 1.8 eV (690 nm) and 2.7 eV (460 nm). The particle sizes of the photocatalyst obtained in a range of about 100 nm to 1.2 μπι (average particle diameter), as based on scanning electron microscopy (SEM) was determined (see Figure 4). On the basis of conducted Kathodolumineszenzmessungen was confirmed that almost all of ZnO was implemented. The two-doped ZnO photocatalytic materials (even a wet chemical and once thennisch doped) were applied as coatings to substrates fine dust reduction measurements showed a reduction of fine particles after 30 minutes to 8% or 6.35%. In control measurements without the inventive photokataiytisch active material of the corresponding end value was significantly higher, at 15.84%. This shows that with the inventive photokataiytisch active coatings air cleaning processes can be speeded up considerably.

Claims

claims
A method for reducing fine dust,
characterized,
that fine particles from a gaseous medium is separated by means of a photocatalytic material.
A method for reducing fine dust,
characterized,
that fine particles from a gaseous medium by means of a photocatalytic material is separated in daylight.
The method of claim 1 or 2,
characterized,
that fine dust is separated from a gaseous medium by means of a photocatalytic material without UV light.
Method according to one of the preceding claims,
characterized,
that the photocatalytic material comprises a photocatalyst and a binder
Method according to one of the preceding claims,
characterized,
the photocatalyst, at least one of the elements Sn, Zn, Bi, Ga, Ge, In, Ta, Ti, V, W, Sb, or comprises Tl.
Method according to one of the preceding claims,
characterized,
the photocatalyst Sn and / or comprises Zn.
7. The method according to any one of the preceding claims,
characterized,
that the photocatalytic material comprises silanes as a binder.
5 8. A method according to any one of the preceding claims,
characterized,
the photocatalyst with one or more elements, eye selects Co, C, N, P, S or H is doped. lo 9. The method according to any one of the preceding claims,
characterized,
the photocatalyst with one or more elements selected from Pb, Au, Ag, PL AI, Cu, Sb, Mo, Fe or Cd is loaded i5 10. The method according to any one of the preceding claims,
characterized,
that the photocatalytic material is applied to a substrate, in particular on glass, metal, building materials and / or ceramic.
30. 1 Method according to one of the preceding claims,
characterized,
that the method is carried out for reducing fine dust in an open system. s 12. The method according to any one of the preceding claims,
characterized,
that it is carried out in the absence of light with a wavelength <350 nm. o 13. The method according to any one of the preceding claims,
characterized,
that it is in the particulate matter by particles having a mean particle diameter of £ 50 pm, is particularly £ 100 nm. Photocatalyst is active without UV light,
characterized,
Photokataiysator that the one or more elements selected from Sn, Zn, Ta, Bi, In, V, W, Sb, Ge, Ga, Tl and / or includes Ti.
15. photocatalyst according to claim 14,
characterized,
that it comprises tin oxide and / or zinc oxide.
10
16. photocatalyst according to claim 14 or 15,
characterized,
is that the photocatalyst with one or more elements, eye selects Co, C, N, P, S or H, doped, or the i5 photocatalyst with one or more elements selected from
Is loaded Pb, Au, Ag, PL AI, Cu, Sb, Mo, Fe or Cd.
Photocatalytic material comprising a photocatalyst, in particular a Photokataiysator according to any one of claims 14 to 16, and a binder,
characterized,
that it is the binding agent is a silane.
A method for reducing fine dust from air,
characterized,
fine dust from air that is separated by an applied on glass photocatalytic material without UV light.
19. The method according to claim 18,
0 characterized in
that the photocatalyst has particle sizes of <300 nm.
PCT/EP2012/065968 2012-07-11 2012-08-15 Photocatalytically active material for purifying air WO2014008953A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP12175952.6 2012-07-11
EP12175952 2012-07-11
EP12178074 2012-07-26
EPEP12178074 2012-07-26

Publications (1)

Publication Number Publication Date
WO2014008953A1 true true WO2014008953A1 (en) 2014-01-16

Family

ID=49915425

Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
WO (1) WO2014008953A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6387844B1 (en) * 1994-10-31 2002-05-14 Akira Fujishima Titanium dioxide photocatalyst
US20090093359A1 (en) * 2004-10-27 2009-04-09 Suminoe Textile Co., Ltd. Fiber Fabric Having VOC Removing Function
US20090192032A1 (en) * 2008-01-29 2009-07-30 Seoul National University Industry Foundation Visible light-responsive photocatalyst composition containing tungsten-based oxides and method of producing the same
US20110142725A1 (en) * 2009-12-10 2011-06-16 Honeywell International Inc. Air purification apparatus and method of forming the same
EP2407236A1 (en) * 2010-07-13 2012-01-18 Theta Chemicals Limited Photocatalyst comprising a doped material

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6387844B1 (en) * 1994-10-31 2002-05-14 Akira Fujishima Titanium dioxide photocatalyst
US20090093359A1 (en) * 2004-10-27 2009-04-09 Suminoe Textile Co., Ltd. Fiber Fabric Having VOC Removing Function
US20090192032A1 (en) * 2008-01-29 2009-07-30 Seoul National University Industry Foundation Visible light-responsive photocatalyst composition containing tungsten-based oxides and method of producing the same
US20110142725A1 (en) * 2009-12-10 2011-06-16 Honeywell International Inc. Air purification apparatus and method of forming the same
EP2407236A1 (en) * 2010-07-13 2012-01-18 Theta Chemicals Limited Photocatalyst comprising a doped material

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

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