DE19746343A1 - Method for photo chemical and biological reactions - Google Patents

Abstract

Method for photo chemical and biological reactions in which in order to apply solar energy to a photo reactor (10), containing a photo absorber and a reaction medium, the solar rays striking the system are passed to a medium which shifts the wavelength and absorbs at least part of the solar rays to give radiated energy in a different wavelength. The radiated energy is passed to the photo reactor either directly or after further conversion. An Independent claim is also included for the apparatus used, where the rays passed to the photo reactor (10) match the absorption spectrum of the photo absorber, to give a photonic conversion with a high quantum yield. The photo absorber flows in and out with the reaction medium or is a component part of the photo reactor. The wavelength shift is through a shaped polymer body (15) or at least one embedded polymer layer with an embedded fluorescent additive, or a number of additives with different absorption and emission behaviors. The radiation is fed to the photo reactor, together with part of the solar rays. The medium to shift the wavelength is after the reaction medium, in the ray path, in direct contact or separated by a transparent or semi-transparent wall. The photo reactor has at least one serpentine channel, with its wide side against the solar rays. The photo reactor can hold inserted photo absorbers in a transparent matrix body with a fluorescent additive. The solar rays can be concentrated at the medium to shift the wavelength.

Description

The invention relates to a method and a Vorrich device for introducing solar radiation energy into one Photoreactor to carry out photochemical or photobiological reactions with sunlight.

To activate a photochemical or photobiolo Reaction must electromagnetic radiation be sorbed. On the one hand, it can be from a stock part - e.g. B. a functional group - the Reak tion to be brought chemical compound or from a Cell or part of a cell, on the other hand also from a sensitizer, the energy or one Charge to the system to be reacted carries, or from a catalyst that after activation through which radiation controls the course of the reaction,  be absorbed. Such a component, Sensibi lizer, catalyst or the like is in connection with this invention hereinafter as "photo absorber" be draws.

From the light of a broadband emitter - especially from sunlight - can often only one Part of the radiation for that photochemical or photobiological reaction can be used. Kurzwel Light in some reactions can cause unwanted Ne cause ben reactions or cell damage. light Larger wavelengths is for the electronic type excitement not energetic enough. But there are also cases le in which short-wave radiation is a desirable photochemical or photobiological effect partially calls him while longer-wave radiation or completely reversed again. Within the for the photochemical or photobiological reaction ge suitable wavelength range is the light of some Partial areas absorbed to a higher degree than light other areas.

The success of a particular photochemical or photo biological reaction depends to a large extent on the selection of a suitable light source and the spectral selection of the light. In particular, the quality of a photochemical or photobiological reaction, which can be expressed by conversion, selectivity, space-time yield and the desired photobiological effect against an accompanying undesirable effect, by the arrangement of the radiation source, its power and its spectral distribution to be influenced. Advances in the technical execution of photochemical and photobiological applications are therefore taking place in parallel with the development of suitable radiation sources and methods for the selection and amplification of the desired spectral range. An overview of the state of the art in solar photochemical and photocatalytic technology was recently published. It also identified the most important problems to be solved in order to initiate commercialization (K.-H. Funken, DM Blake, M. Romero, I. Spiewak, Recent Developments in Solar Photochemistry: Status and Perspektives, in: M. Becker , M. Böhmer (eds) Proc. 8 ^th Int.Symp.Sol.Sentrentrating Technol., October 6-11, 1996, Köln, Germany, CF Mül ler Verlag Heidelberg (1997) vol. 3 1325-1336).

To the photo realized on an industrial scale chemical processes with the aim of producing Chemicals include photohalogenations, photosul chlorination, photosulfoxidation, photonitrosia stanchions, photoisomerizations, photohydrodimerization stations, photodesulfonations, photosulfonylations and photo oxygenations. But there are also more Reak not yet carried out on an industrial scale tion types known under the influence of elec tromagnetic radiation with great selectivity lead refined products.

One can also be high through photobiological implementations win refined products. Areas of application for the products made from phototrophic cyanobacteria, Algae and microalgae are available in medicine, pharmacy, cosmetics, the farmer society, nutrition and the environment technology. For example, dyes and coloring foods (e.g. phycocyanins, phycobili  proteins and carotenoids), polyunsaturated fat acids (especially arachidonic acid, eicosapentaen and Docosahexaenoic acid), antioxidants (e.g. tocopherol), Produce proteins and polysaccharides. Also pharma ecologically active substances (antibactericides and anti fungicides) were identified in different microalgae fected.

In the field of environmental technology, photochemical and photobiological process developed to by harmful Water contaminated with substances and / or microorganisms or to detoxify and / or sterilize gas flows. Common to these processes is that under photo African excitation singlet oxygen, hydroxyl or other oxygen radicals that are formed then the pollutants to be broken down or those too inacti attack four microorganisms. That's how education is excited oxygen species possible and known by Energy transfer from an electronically excited Donor, by excitation of a semiconductor material, such as e.g. B. titanium dioxide or by photo-Fenton reagents.

To carry out the photochemical or photobiolo Different light sources are available for implementation available, e.g. B. gas discharge lamps, incandescent lamps, fluorescent lamps or tubes as well as lasers. Each these light sources have characteristic properties with regard to the type of spectrum emitted and the luminosity. The spectrum can only be limited tem scope by tampering with the lamp, such as. B. Use of different lighting media, doping or Changes in pressure. Furthermore, by Filter glasses or liquid filters (e.g. solutions be certain salts or organic components)  of the spectrum are absorbed. Such measures can however, shorten the life of the lamps or a higher expenditure on equipment and thus higher Cause costs. Also an increase in the luminosity is only possible to a limited extent and usually with a higher one Power consumption and an increase in lamp volume connected. With fluorescent additives in the lamps you can use the light provided Absorption characteristics of the photonic system fit, but it is disadvantageous that they are very dif fuse light sources and their light are not efficient can be focused on a reaction vessel. With Lasers can be intense radiation from a ge desired wavelength, but yours Installation and operation are so expensive connected that their use for economic reasons can only be justified in very special cases.

Instead of electrically powered light sources, too the solar radiation to carry out photochemical and photobiological implementations. since For a long time, the use of voluminous, transparent or even more open or through transparent covers reaction vessels shielded from the environment known to be exposed to solar radiation. In more recently, line or point focus has also become concentrators used to direct radiation to bundle the sun into the reaction apparatus.

In the patent DE 44 23 302 C1 a Vorrich device for coupling radiation energy into one Photoreactor described by holographic pre direction uses to derive from that of the respective only a part of the light source supplied  to bundle the inside of the reactor. This brings the Advantages that only the radiation in the reactor is directed to the photochemical in question Response is useful. So side reactions, that would be triggered by light that is too short, and an undesirable heating due to the absorption of too long-wave light, which leads to increased expenses for cooling would be avoided. Indeed is a use of the hidden radiation for the photoreaction of interest not possible.

For both photochemical and photobiological Applications are the cost of deploying the Light of considerable importance. With electrical be Driven light sources primarily involve high investments costs for lamps, power supply and security safety measures and operating costs for the Lampener set by the limited life of the lamps cooling and electrical current. A Another disadvantage is that usually only one often a small part of that emitted by the emitter Light can be used for the relevant implementation. With Systems powered by sunlight do not have all of these Disadvantages. In particular, the high In investment costs for lamps and power supply and operating costs for lamp replacement and electrical Electricity. The effort for cooling is also significant less than with lamp-powered systems. From The disadvantage compared to the lamp-operated systems is but that solar photochemistry and photobiology can only be carried out during the hours of sunshine. There is a chance that at suitable locations with Sunlight powered photochemical or photobiolo overall systems cost  work cheaper than those operated with artificial light. So are already some photobiological syntheses of highly refined products industrially with suns light done. It’s for solar photochemistry, but also disadvantageous for solar photobiology, that only a part of the solar spectrum affects the fende photonic implementation can be used. A the host would have better photonic efficiency sustainably increase profitability.

The invention has for its object a method and provide a device to better out use of the solar spectrum for photochemical and / or enable photobiological applications.

This object is achieved with the invention the method according to claim 1 and with the front direction according to claim 5.

The basic feature of the Lö according to the invention solution path is that either the entire Spectral range of solar radiation or one for that interesting photonic conversion not usable Part of the spectral range with a wavelength ver interacting pushing medium To emit radiation in the interested Spectral range lies. The shifting wavelength Medium absorbs part of the solar radiation and then in turn emits radiation which in another wavelength range. A typical one Wavelength-shifting medium is fluorescent Material. According to the invention in the previously be knew devices of unusable part of the suns radiation in the favorable for the photonic reaction  Spectral range shifted. Thus, the on integral radiation power of solar radiation bezo gene usable portion of the photonic energy clearly increased.

Fluorescent additives are generally used det, the short-wave light into longer-wave light transform such. B. UV radiation in blue, green nes, yellow or red light (down-conversion). Useful But is also interesting and interesting in the case of the suns the conversion of infrared light into the radiation visible spectral range (up-conversion). Cheaper the additives are chosen so that their Emis sion spectrum a most effective photonic Re action induced and the proportion of the response spectral ranges not required is small. The Emis sion spectrum of the additives falls favorably together with the absorption spectrum of the chromophore, especially in the area where the Ab sorption spectrum the highest possible extinction has coefficients, and in which on the other hand the pho Tonic implementation with the highest possible quantum yield he follows.

Due to the effect of the features of the invention compared to a significant increase in luminous flux the incident radiation in the for the desired Response required spectral range of solar radiation instead of at the expense of unwanted radiation. The Displacement of short-wave radiation, in particular of the UV component, can in certain cases be particularly their advantage in which they lead to side reactions or cause product damage. The postponement long-wave radiation, especially infrared  Share, can be particularly advantageous if it by components of the reaction mixture, absor would be without the desired photonic order lead, and thus in an unwanted Warming resulted.

The wavelength-shifting medium is preferred as made of polymer moldings and / or polymer layer systems into which fluorescent additives are incorporated were. The volume of the polymer and the concentration of the fluorescent additives can be chosen that a light conversion with regard to that for the photonic implementation with the cheapest spectral range high efficiency and a sufficiently high one Concentration of radiation is effected.

To increase the effectiveness of light conversion several fluorescent additives can be used, which differ in their absorption and emission properties distinguish and complement. There is also the possibility possibility to carry out a multi-stage light conversion, in the first stage, part of the solar spec is implemented on a first spectral range, and in a second stage the second spectral range is converted to a third spectral range.

A concentrator is expediently provided, which the solar radiation on the wavelength shifting Medium concentrated. Such a concentrator exists for example from a channel reflector, in particular a parabolic trough reflector, in the focal line of which Medium is arranged. When using a conc trators are much higher space-time yields of the Reactor feasible.  

The device can also be used with a holographic Combine device that is part of the Hides light that becomes an unwanted companion appearances, e.g. B. side and follow-up reactions or Er warming due to absorption of radiation and does not and does not contribute to the photoreaction economically sensible in the desired spectral spectrum can be moved richly.

The polymer moldings and / or polymer layer systems consist of the difference depending on the application most optical transparent polymer materials, such as B. polymethyl methacrylate, polymethacrylic acid esters, polymethacrylic acids, polyacrylic acids and their Esters, from copolymers of these materials, such as Polymethacrylic methylimides, methyl methacrylate acrylic nitrile vinyl esters, polymethylpentene, acrylic acid sty ren-acrylic acid-vinyl acetate copolymers, made of polystyrene, Polyvinyltoluen, polycarbonates, polyethylenes, poly proyls, cellulose derivatives, polyacetals, polyamides, fluorinated acrylic acid polymers, cycloolefin polymers ren, polyimides, polyallyl phthalates, acetate butyrates, Polyvinyl chloride, polyesters and copolymers of these Materials.

The in the optically transparent polymer moldings and / or polymer layer systems embedded fluores decorative additives are, for example, p-terphenyls, p-quaterphenyls, p-quinquephenyls, oxadiazoles, oxazoles, Diphenylfurans, stilbenes, stryryle, stryrylpyrans, Coumarins, furans, fluoresceins, fuoroles, rhodamines, Uranines, pyrans, cyanine derivatives, cresyl violet, Malachite green, oxazones, oxazines, pyridines, carbazines, Benzoxanthene derivatives, thioxanthene derivatives,  Sulfaflavins, quinolones, azaquinolones, pyrromethenes, Benzimidazoles, diphenylanthracenes, thiophenes, phenyl vinylenes, perylenes, perylenimides, naphthalates, Naphthalimides, naphthols, phthalo- and naphthalocyanines, Porphyrins, 4-dicanomethylene-2-methyl-6-p- dimethylamino-styryl-4H-pyrone, perchlorates, iodides, such as e.g. B. DODC or DTTC iodides or other cataloged fluorescent substances such as B. IR-26, IR-125, IR-132, IR-140, IR-144, Kodak Dye 26, Nil Blue A Perchlorate, POPOP, HPTS, as well as DCM, HITCI, DOCI, DMETCI or Pyridinphenylborate (ASPT) and Aminophenylsul fonylstilbene (APSS).

In the following with reference to the drawing Solutions embodiments of the invention he closer purifies.

Show it:

Fig. 1 shows a first embodiment of a Vorrich tung with two-stage Spektralumsetzung,

Fig. 2 shows another embodiment with clas figer Spektralumsetzung and lateral line A of the wavelength-shifted radiation in the reactor,

Fig. 3 shows a third embodiment of the device having a meandering extending channel,

Fig. 4 shows a section along the line IV-IV of Fig. 3,

Fig. 5 shows an embodiment in which the solar radiation first passes through part of the reaction medium and then strikes the wavelength-shifting medium, and

Fig. 6 shows an embodiment in which the Photoab sorber consists of internals contained in the reactor.

In the exemplary embodiment according to FIG. 1, the photoreactor 10 consists of a reactor tube 11 through which the reaction medium flows. The reactor tube 11 is made of glass or another transparent Ma material. The reaction medium flowing in the reaction tube contains a (not shown) photoabsorber, which is pure, homogeneously dissolved in any solvent or dispersed heterogeneously in any fluid in the reaction medium in the liquid phase, as carrier gas carried particles or aerosols or as vapor clean or with a Carrier gas mixed is passed through the reactor 10 .

The reactor tube 11 is first immersed in the immersion process with a polycarbonate layer 12 , which contains 10 percent by weight of perylene red - based on the weight fraction of the polycarbonate. This is followed by coating with a layer 13 made of PMMA, which contains 8 percent by weight of a fluorescent coumarin or phthalimide as an additive. The layer thicknesses of the individual polymer layers are in the range between 10 µm and 1000 µm.

The solar radiation 14 first strikes the doped PMMA layer 13 , its UV component and radiation in the blue spectral range being transformed into longer wavelengths. The transformed radiation and original sun rays of higher wavelength then reach the doped polycarbonate layer 12 . After absorption, there is an emission in the red spectral range with high light amplification, the radiation intensity in the UV and blue as well as in the green and yellow spectral range being significantly reduced. So there is a two-stage spectral shift at.

In the embodiment of Fig. 2, the wel lenlängenverschiebes medium from a Polymerformkör by 15 in the form of a flat plate, on the upper side 16, the solar radiation 14 strikes. At the upper surface 16 , a small portion 17 of the solar radiation is reflected. This proportion can be reduced by applying an antireflective layer. The solar radiation reaches the transparent polymer molded body 15 with refraction of light at the boundary layer, where it continues at a different angle and strikes a fluorescent dye center Z. With a sufficiently large angle of incidence, the fluorescence emitted undirected by the dye center Z becomes light at the boundary layers between polymer molded bodies 15 and Air totally reflected and possibly hits the boundary layer 18 to the reaction space 20 of the photoreactor 10 after more total reflection. Due to the small difference in the refractive index, no total reflection takes place at the boundary layer 18 , so that the light can enter the reaction medium flowing in the photoreactor.

At the end of the poly merform body 15 facing away from the photoreactor 10 there is a mirror layer 19 which ensures that the radiation is reflected back into the polymer molded body and does not emerge from it. However, a small part of the fluorescent light emitted by the dye centers Z emerges from the polymer molded body and is lost, which is indicated by the arrows 21 .

Another embodiment of the device is shown in FIGS. 3 and 4. Here, the poly merformkörper 15 consists of a plate made of polymethyl methacrylate (PMMA) or polycarbonate (PC) with an incorporated fluorescent additive of about 0.05 weight percent. The base area of the plate is, for example, 100 cm × 20 cm and the thickness is 20 mm. The polymer molded body 15 contains a meandering channel in the plat tenplane extending between two opposite side edges 31 he stretches. The side edges 31 are with light reflecting layers, z. B. made of silver or aluminum. The surface 32 facing the solar radiation is coated with an anti-reflection layer 33 . A reflective layer 34 is located on the underside of the molded polymer body 15 .

If the diffuse or direct solar radiation hits the surface 32 of the polymer molding, it arrives with the exception of reflection losses in the channel 30 , in the volume of the polymer molding and is absorbed there to a large extent and emitted with its wavelength shifted almost isotropically. Due to total reflection and reflection on the main surfaces of the molded polymer body, most of the radiation is guided in a wave-guiding manner in the molded polymer body 15 , where with sufficient geometric expansion of the main surfaces - in relation to the surfaces of the side edges 31 - a high concentration of radiation on the surfaces of the meandering channel 30 is reached. A concentration of the radiation on the channel 30 carrying the reaction mixture can thus be achieved almost by a factor of 10 if the dimensions D1 and D2 are approximately 70 mm, the dimensions D3 are approximately 10 mm and the thickness D4 of the polymer molding is approximately 18 mm. Any number of consecutive and / or parallel reactors can be put together to form a photoreactor.

The channel 30 carrying the reaction mixture can be formed by glass tubes. This has the advantage that reaction mixtures or solvents which are not resistant to PMMA can also be used. In its manufacture, the PMMA plate was doped with 0.02 percent by weight with the fluorescent dye perylene red 300.

Due to the presence of the fluorescent dye there is a light intensifier on the surfaces of the channel kung in the red spectral range above 600 nm Light emission can be advantageous for example photochemical reactions can be used by Be sensitized to methylene blue because the absorb tion maximum of methylene blue is 660 nm is of particular technical interest Methylene blue sensitized formation of singlet Oxygen. Terpene olefins react selectively and under high added value with singlet oxygen under bil formation of peroxides and hydroperoxides, the intermediate products for the manufacture of fragrances. Such terpene olefins include both acyclic ter  penes, which may contain hydroxyl groups (e.g. Citronellol, myrcene, myrceneol, nerol, geraniol, lina lool, lavandulol, ocimen), monocyclic terpenes (e.g. Limonene, α- and γ-terpinene, terpinolene, α- and β-phel landren) and bicyclic terpenes (e.g. α- and β-pinene, Camphen, Caren, α-Thujen). For example, the very selective reaction of singlet oxygen with Furfural or with furan-2-carboxylic acid for easy Synthesis of maleic aldehyde pseudo acid from technical Interest. The product can be used to synthesize a large Range of fine chemicals can be used.

In the embodiment of FIG. 5, a reaction tube 11 is seen as in the first embodiment. A concentrator 40 in the form of a parabolic reflector concentrates the sunlight on the central area of the reactor tube 11 made of transparent material. In this central area, the wavelength-shifting medium and the photo-absorber are located in a polymer molding 41 . The light is first passed through the reaction medium 42 with absorption of some of the light. The non-absorbed part of the light interacts with the wavelength-shifting medium, which is located in the polymeric molded body 41 . The wavelength-shifted radiation then emitted by this medium enters the reaction medium 42 and is absorbed therein.

In the embodiment of FIG. 6, a photoreactor 10 in the form of a transparent reactor tube 11 is also present. A concentrator 40 in the form of a parabolic trough reflector is also provided, which concentrates the solar radiation on the center of the reactor tube. The reactor tube 11 contains a coaxial longitudinal rod 45 . Both on the inner wall of the reactor tube 11 and on the rod 45 there are photoabsorbers 46 in the form of internals which are an integral part of the photoreactor. These internals consist of platelets, which are connected to the wall of the reactor tube or the inner rod 45 by webs. The photo absorber, which consists of internals of the reactor and flows around the reaction medium, can also be chemically bound to the surface of the reactor facing the medium. He can also on the surface of a bed of filler bodies of any geometry, a structure of any geometry, for. B. a network, braid or foam. The wavelength-shifted medium is not shown in FIG. 6. It can be made of a coating on the outside of the reactor tube 11 be.

Claims (16)

1. A method for introducing solar radiation energy in a photoreactor ( 10 ) containing a Photoab sorber and a reaction medium, characterized in that the incident solar radiation is supplied to a wavelength-shifting medium which absorbs at least part of the solar radiation and in radiated energy from different wavelength than that of the absorbed radiation converts, the emitted radiation being passed directly or after another conversion into the photoreactor. 2. The method according to claim 1, characterized in that the radiation guided into the photoreactor ( 10 ) is adapted to the absorption spectrum of the photo absorber, so that photonic conversion takes place with a high quantum yield. 3. The method according to claim 1 or 2, characterized records that the photo absorber in the reaction medium is included. 4. The method according to claim 1 or 2, characterized records that the photo absorber is part of the Is photoreactor.   5. Device for introducing solar radiation energy in a photoreactor that has a photoab sorber and contains a reaction medium, thereby characterized that a wavelength shifting Medium is provided, which is the incident solar receives radiation and at least part of it Absorbs solar radiation and radiates in Energy of a wavelength other than that of absorbed radiation, and that the photo reactor is arranged such that it is the abge emitted radiation directly or after repeated Implementation receives. 6. The device according to claim 5, characterized in that the wavelength-shifting medium is a polymer molded body ( 15 ) or a polymer layer system ( 12 , 13 ) with at least one embedded fluorescent additive. 7. The device according to claim 6, characterized in net that the polymer molded body or the polymer layer system several fluorescent additives contains, which are in their absorption and emis differentiate. 8. Device according to one of claims 5-7, characterized characterized in that the radiated radiation along with a solar radiation portion of one same spectral range in the photoreactor entry.   9. Device according to one of claims 5-7, characterized in that the wavelength-shifting medium ( 41 ) is arranged behind the reaction medium ( 42 ) in the radiation path of the solar radiation. 10. Device according to one of claims 5-9, characterized characterized in that the reaction medium in direk contact with the wavelength shifting Medium is. 11. The device according to any one of claims 5-9, characterized characterized in that the reaction medium by a transparent or semi-transparent wall of that wavelength-shifting medium is separated. 12. Device according to one of claims 5-11, characterized in that the photoreactor holds at least one meandering channel ( 30 ) ent, the broad side of which is exposed to solar radiation. 13. Device according to one of claims 5-12, characterized in that the photoreactor contains the Photoab sorber ( 46 ) in the form of internals. 14. The apparatus according to claim 13, characterized net that the photo absorber in a transparent Body matrix is included.   15. The apparatus according to claim 13, characterized net that the photo absorber in a body matrix is included, the fluorescent additives ent holds. 16. Device according to one of claims 5-15, characterized in that a concentrator ( 40 ) is provided which concentrates the solar radiation onto the wavelength-shifting medium.