LIGHT RECACTOR AND METHOD FOR SYNTHETIC MATERIAL PROCESSING BY MEANS OF LIGHT IRRITATION

Description

[0001] The present invention relates to a light reactor for the synthetic production and / or photochemical treatment of substances, comprising a receiving chamber for receiving substances to be processed and / or a reaction vessel for the substances to be irradiated, at least one light source, and optics for redirecting the light from the light source onto the receiving chamber. The invention further relates to a method for the synthetic production and / or treatment of substances using such a light reactor.

[0002] More recently, attempts have been made to synthesize hydrogen in light reactors. In this process, water, along with a substrate and one or more catalysts, is irradiated with light in a receiving chamber of a light reactor. A chromophore, i.e., a dye or color carrier, absorbs the light and transfers the light energy to the water via a water reduction catalyst, resulting in the conversion to H₂. The chromophore and other substances used are capable of repeating this reaction, thus identifying them as catalysts.

[0003] However, the aforementioned light reactors are also used for other photochemical treatments and production processes, whereby the substances to be irradiated are usually placed in a reaction vessel such as a glass flask or a transparent vial in the receiving chamber of the container, in order to be selectively irradiated with light, which can cause or initiate the desired reaction.

[0004] For example, the document WO 2018 / 098189 A1 describes a light reactor whose reactor housing has an opening through which a vial containing the substances to be irradiated can be inserted into a receiving chamber inside the housing. A UV light source located outside the housing shines light through a second opening into the housing. Inside the housing, this light is deflected by several mirrors to selectively irradiate the receiving chamber and the vials located there. However, the efficiency of this known reactor is limited. Firstly, the radiation field in the receiving chamber is not very homogeneous. Secondly, the power density in the area of ​​the inserted glass bulbs is relatively low, so that certain synthetic applications cannot be initiated at all or at least take an excessively long time.At the same time, it is time-consuming to be able to adjust the required or useful spectral range for different reactions and to convert the light reactor accordingly.

[0005] From German patent application DE 11 2010 005 248 T5, it is known to use LED strips with cluster-like distributed LEDs for photoinduced curing processes, with the patent expecting to achieve a more uniform radiation intensity through such a cluster-like LED array. However, such uniformity is likely to be limited to the large-area photographic papers or plates to be treated. For a reactor with a receiving chamber in which various substances to be treated are positioned, preferably in glass bulbs or similar reactor vessels of varying dimensions, the LED strips are unsuitable and hardly capable of directing the emitted light precisely onto a defined reaction space.

[0006] The present invention is based on the objective of providing an improved light reactor and an improved method for the synthetic treatment and / or production of substances using such a light reactor of the aforementioned type, avoiding the disadvantages of the prior art and advancing the latter in an advantageous manner. In particular, efficient irradiation of the substances in the receiving chamber with high power density and uniformity is to be achieved, which is easily adaptable to different reaction types and can be precisely controlled.

[0007] According to the invention, the aforementioned problem is solved by a light reactor according to claim 1, a method for synthetically treating and / or producing substances by light irradiation according to claim 13, and the use of a light reactor according to claim 15. Preferred embodiments of the invention are the subject of the dependent claims.

[0008] It is therefore proposed to distribute a multitude of light sources and associated optical elements in a ring around the receiving chamber of the light reactor in order to illuminate the receiving chamber simultaneously from different directions. According to the invention, the multitude of light sources and the multitude of optical elements are arranged in several rows distributed around the receiving chamber, with each optical element being configured to direct the captured light onto the receiving chamber located at the center of the ring-shaped light source and optical element arrangement.The optical elements, with their main emission axes, are arranged at different angles from row to row relative to the longitudinal axis of the annular area in which they are distributed around the recording area. This tilting causes the light beams formed by the optical elements to collectively create a constricted radiation space, narrowed between two cone apexes and centered in the central region of the recording area. The radiation space formed by the light beams constitutes a body that is at least approximately rotationally symmetric. Its circumferential surface is formed by the multiple rows of optical elements, while its end faces are formed by two virtual cones extending coaxially to the aforementioned longitudinal axis of the annular area. These cones' apexes point towards each other, and the apexes may touch or be positioned very close to one another.The radiation space formed jointly by the light beams is thus constricted in an approximately hourglass or hourglass shape, contoured like a shell that encloses the constricted area of ​​an hourglass. The virtual cones that delimit the radiation space between them need not have an exact conical shape in the mathematical sense, although they can, but can form two approximately conical points or two mountain peaks, whose possibly rounded or flattened tips are arranged at least approximately coaxially towards each other.

[0009] By constricting the radiation field in this way, the individual light beams overlap in the center of the receiving space, thereby achieving very high intensities. Such high light intensities enable non-linear reactions that could not be achieved with lower intensities, even with very long exposures. Similar to a dam breaking, exceeding a certain intensity can lead to the production of an alternative substance or the synthesis of a different synthetic substance, which could not be achieved below a certain intensity threshold, even with very long exposures. Such two-photon excitation, or non-linear optical excitation, can also be achieved with lower-power light sources, such as LEDs, thanks to the inventive design and arrangement of the optical elements, which generate the radiation field constricted between two cones in the manner described.

[0010] By using a variety of light sources and associated lighting elements, the required spectral range can be easily and variably adjusted. Simultaneously, the ring- or spherical distribution around the recording area creates a highly homogeneous radiation field in the central region of the system, thus maximizing reaction efficiency. This allows for high power densities, which significantly reduce the time required for the desired reaction.

[0011] In an advantageous embodiment of the invention, the light sources and / or optical elements can be arranged with their principal emission directions or axes in a matrix-like or cloud-like distribution. The aforementioned principal emission axes of the optical elements are aligned perpendicular to a common spherical surface around the center of the receiving space. In other words, the light beams formed by the optical elements, with their principal axes, fall approximately radially towards the center of the receiving space from different sides and directions onto the materials to be treated, so that the light beams incident from different sides converge in the receiving space.

[0012] Separate light beams are formed at the various optical elements. These beams do not yet overlap at the optical elements themselves, but then meet and overlap in the central area of ​​the recording chamber. The optical elements are arranged in a ring-shaped area around the recording chamber, ensuring uniform illumination and overlap of the light beams within the chamber, while simultaneously maintaining practical handling, such as inserting and removing a recording vessel.

[0013] The optical elements can be arranged in a point-symmetrical manner with respect to the center of the recording space, such that opposing pairs of optical elements have coaxial principal radiation axes, at least approximately. All principal radiation axes can intersect at a common point, which forms the center of the recording space. This common intersection point need not be a point in the mathematical sense, but can have a certain extent, so that the principal radiation axes of the optical elements essentially form a tangled point as their common intersection.

[0014] The light beams themselves can be constricted by the optical elements in an hourglass shape, so that the constriction of the light beam is located in the center of the recording space, whereby the optical elements arranged in several rows in a ring shape can be aligned in such a way that the constriction areas of the light beams overlap in the said center of the recording space.

[0015] The main emission axes of the optical elements arranged in a ring array can have the same tilt relative to the ring's longitudinal axis, while the tilt varies from row to row. For example, a central row of optical elements may have main emission axes extending perpendicular or radially to the ring's longitudinal axis, while the main emission axes of the optical elements in adjacent rows may be tilted at an acute angle α and an acute angle -α or -β relative to the longitudinal axis of the ring-shaped area. For instance, the main emission axes of the optical elements in an upper row might extend downwards at an angle of, say, 70° to 80° to the ring's longitudinal axis, and the main emission axes of the optical elements in a lower row might extend upwards at an angle of 70° to 80°.In other words, the main emission axes of the optical elements in one ring row can, for example, extend parallel to a plane perpendicular to the ring's longitudinal axis, while the main emission axes of the optical elements in another ring row can extend at an angle to said plane perpendicular to the ring's longitudinal axis. The angles of inclination can change stepwise from row to row, although the angles of inclination of the optical elements arranged in a row can be the same.

[0016] In particular, the optical elements can be arranged side by side or one above the other in a matrix-like or cloud-like distribution on a common, spherical surface and be essentially the same distance from the center of the recording space to be irradiated. However, it would also be possible, in principle, to arrange the optical elements at different distances from the center of the recording space to be irradiated, for example, by positioning them on two or three spherical surfaces with different diameters. The optical elements arranged in this staggered manner can nevertheless have their main emission axes oriented radially to the center of the recording space, or the multiple spherical surfaces of different diameters on which the optical elements are distributed can be concentric.

[0017] In particular, the light sources and / or optical elements are arranged in a densely packed configuration around the recording area. To achieve the densest possible arrangement on a common, curved – virtual – surface, the optical elements can be offset into the spaces between adjacent optical elements or nested within each other to make the best possible use of the spaces created by the outline contours of the optical elements. This allows for a high power density to be achieved in a compact design.

[0018] Advantageously, the light sources and / or optical elements can be arranged on an annular strip of a common spherical surface, the center of which forms the center of the recording space.

[0019] The light sources and / or optical elements can advantageously be arranged in at least two or three rows above and / or next to each other around the recording space, wherein the rows can each form a ring and / or the optical elements in different rows can have at least approximately the same distance from the center of the recording space.

[0020] In particular, the optical elements, which are arranged in different rows, can have main emission axes tilted relative to each other.

[0021] To enable the densest possible packing or arrangement of the optical elements around the recording space, the optical elements in adjacent rows can be offset from one another, so that an optical element in a first row is positioned approximately midway between two adjacent optical elements in an adjacent second row, naturally exhibiting a transverse offset corresponding to the row width. The offset of the optical elements in the first row relative to the optical elements in the second row is given in the longitudinal direction of the row and can be approximately half the division or half the distance between the centers of two adjacent optical elements in the adjacent row. For example, if 12 optical elements are arranged in a ring-shaped row such that the division between two adjacent optical elements is 360° / 12, i.e., 30°, the adjacent circular row of 12 optical elements can be rotated by 15° relative to the first row.

[0022] If three or more rows of optical elements are provided, the optical elements in the first and third rows can be arranged overlapping each other, or connecting lines can be defined between each pair of optical elements that are perpendicular to the longitudinal directions of both rows. Regardless of the exact orientation of the connecting lines through the nearest pairs of optical elements in the first and third rows, the optical elements in the second or intermediate row can be arranged approximately midway to the aforementioned connecting lines through the optical elements of the first and third rows.

[0023] Depending on the diameter of the optical elements, different numbers of rows of optical elements and / or different numbers of optical elements per row can be provided.

[0024] For example, 5 to 50, 10 to 40, or 15 to 30 optical elements can be arranged circumferentially around the recording space, with, for example, 2, 3, or 4 rows, each with a comparable number of optical elements of the aforementioned size, being arranged one above the other, so that, for example, with three rows, approximately 50 to 70 optical elements can form an approximately spherical field of optical elements.

[0025] Considering the overall approximately spherical optical element array, it defines a spherical contour that extends around the receiving chamber and is open towards an insertion opening of the receiving chamber. Specifically, the spherical optical element array can be open at both the top and bottom to allow for easy insertion of a reaction vessel into the receiving chamber from above, while also providing a base for the vessel from below. However, it would also be possible to design the spherical optical element array to be open only towards the receiving chamber opening and, for example, to close it at the bottom, such as when the reaction vessel can be held in the receiving chamber by a holder from above.

[0026] If one considers a cross-section of the spherical optical element field, the spherical ring segments can enclose a segment angle in the range of 30° to 90° or 40° to 70°, which provides a good compromise between high power density and easy insertion of the reaction vessel.

[0027] Advantageously, the optical elements can be rotationally symmetric and / or have a preferably circular circumferential contour, wherein the optical elements can be aligned with their axes of rotation towards a common center of the recording space.

[0028] If the optical elements have a polygonal cross-sectional contour, e.g., hexagonal, the strip-shaped circumferential sections can be aligned by rotating them accordingly around the axis of rotation. In particular, a circular circumferential contour can also be provided.

[0029] In a further development of the invention, an optical element can be assigned to each approximately point-like light source, wherein the light source can in particular be an LED or an LED cluster with preferably different colored individual LED elements. For example, a cluster-like LED module with 2, 3 or 4 individual LED elements arranged directly next to each other and mounted on a common carrier board can be provided and assigned to an optical element that captures the emitted light of the LED cluster and directs it to the center of the receiving space.

[0030] Advantageously, the aforementioned LEDs can be aligned radially with their main emission axes to a common spherical surface and / or directed towards the center of the recording space. Regardless of whether the main emission axis is radial or directed towards a common center, the LEDs can advantageously be oriented so that the emitted direct light is directed towards the center of the recording space. In other words, the LEDs can be oriented into the recording space.

[0031] The optical elements can be designed in fundamentally different ways, whereby lenses in particular can be provided as optical elements which can advantageously capture the light of the respective assigned light source completely and form it into a beam of light that is directed towards the center of the recording space.

[0032] Alternatively or additionally, at least one or more light sources can also be assigned a reflector as an optical element, which captures the emitted light of the light source and forms it into a beam of light that is directed towards the center of the recording space.

[0033] It is also possible to design part of the optical elements as a lens and another part of the optical elements as a reflector.

[0034] Alternatively or additionally, hybrid forms of lenses and reflectors are also possible, for example in such a way that a reflector collar is molded onto a lens and / or a lateral surface of a lens is coated with a reflective material.

[0035] Advantageously, light sources of different colors can be provided, so that different colors or spectral distributions can be achieved by controlling the light sources differently. Different colored light sources can be assigned to different optical elements. If LED clusters with individual LEDs of different colors are used in the aforementioned manner, different colors can also be generated at a single optical element.

[0036] Advantageously, light sources of the same color are arranged on opposite sides of the recording space, in particular arranged opposite each other in a point-mirror symmetrical manner with respect to the center of the recording space, in order to create a homogeneous radiation field for the respective color channel and to facilitate sensor-based in-situ control or detection.

[0037] Advantageously, light sources of at least one color can be designed or controlled to be dimmable, in order to enable multispectral illumination of the recording space and / or to have greater variability in adjusting the light spectra.

[0038] The invention is explained in more detail below with reference to a preferred embodiment and the accompanying drawings. The drawings show: Fig. 1: a perspective view of a light reactor according to an advantageous embodiment of the invention, wherein the reactor has a closable opening on its upper side for inserting a reaction vessel, Fig. 2: a perspective view of the receiving chamber of the light reactor and the optical elements arranged around it for irradiating a reaction vessel positioned in the receiving chamber, Fig. 3: a schematic representation of the spherical array of optical elements around the receiving chamber, wherein Fig. 3athe point-symmetrically arranged, opposite, different color channels are presented in perspective and Fig. 3b a sectional view of the spherical arrangement of the optical elements shows and Fig. 3c Fig. 4 shows the radiation space constricted between two cones, which the light beams of all emitters form together, Fig. 4: a representation of the energy field distribution in the center of the receiving space orthogonal to the central radiation axis of a respective light beam, and Fig. 5: a schematic representation of an embodiment in which daylight supply to the optical elements is provided via light guides and the ends of the light guides function as light sources.

[0039] How Figure 1 As shown, the light reactor 1 comprises a closed or lockable housing 2, which can, for example, be essentially cylindrical and can stand upright on the ground with a base.

[0040] The reactor housing 2 has a closable filling opening 3, which is closed by a cover 4.

[0041] Inside the housing 2, an optical element array 5 is provided, comprising a multitude of optical elements 6 and extending in a ring shape around a receiving space 7, which is accessible through the aforementioned filling opening 3 of the housing 2 and into which a reaction vessel 8, for example in the form of vials or glass bulbs, is inserted through the aforementioned filling opening 3 - for example from above.

[0042] How Figure 2As shown, a mounting bracket 11 for holding or securing the reaction vessels 8 can be provided in the receiving chamber 7. Alternatively, it would also be possible to simply place the reaction vessels 8 on a base 13 or a platform-like surface inside the housing 2. It is also possible to suspend the reaction vessel 8 from a ceiling of the receiving chamber 7, for example from the lid 4.

[0043] As the Figure 2 and 3 As shown, the optical element field 5 is designed in the overall manner of a spherical ring, which is open on one side towards the bottom 13 of the housing 2 and on the other side towards the filling opening 3 of the housing 2.

[0044] In particular, the optical elements 6 can be arranged in a matrix-like distribution on a spherical surface 9, such that the optical elements 6 each look towards the center of the recording space 7 or are aligned with the main emission axes towards the center 10 of the recording space 7 inside the optical element field 5.

[0045] The optical elements 6 mentioned above can advantageously be designed as lenses, which can be injection-molded from transparent silicone, for example, or manufactured in another way, for example from another plastic or from glass. The optical elements 6 mentioned above can be rotationally symmetrical and have their axis of rotation directed towards the center 10 of the receiving space 7. For example, circular or polygonal, for example hexagonal, lenses and / or reflectors can be provided in cross-section. If, for example, hexagonal reflectors and / or lenses are provided, a practically gapless, very dense packing of the optical elements 6 on the arrangement surface 9 can be achieved.

[0046] When arranged on the spherical surface 9, the optical elements 6 are essentially the same distance from the center of the recording space 7.

[0047] As the Figure 2 and 3As shown, the optical elements 6 can be arranged in several ring-shaped rows on the spherical surface 9, wherein the optical elements 6 in one row can be offset from the optical elements 6 in the other row in order to be able to arrange the optical elements 6 as densely packed as possible overall.

[0048] For example, if one considers connecting lines through the centers of each pair of optical elements 6 stacked on top of each other in the top row and in the bottom row, the optical elements 6 in the middle, intervening row are arranged centrally between said connecting lines. In other words, the rows of optical elements 6 can be rotated relative to each other by half the division between any two adjacent optical elements 6 in a row. If, for example, 20 optical elements 6 are provided in the middle row, the upper and lower rows can each be rotated by one-fortieth of 360° relative to the middle row, cf. Figure 3 .

[0049] This allows the space between two adjacent lenses in a row to be used for positioning the optical elements of the adjacent rows. Accordingly, the distance between two rows, measured between the row's central longitudinal lines, can be smaller than the diameter of the optical elements 6.

[0050] The optical elements 6 can have identical contours to each other, in particular all be rotationally symmetric and have circular outline contours, cf. Figure 2 and Figure 3 .

[0051] Light sources 14, preferably configured as LEDs or LED clusters, can be arranged on an outer surface of the optical elements 6. Regardless of whether the light sources 14 are configured as LEDs, each optical element 6 can be assigned its own light source, and the plurality of light sources 14 can advantageously also be arranged distributed on a spherical surface, the center of which can coincide with the center 10 of the receiving space 7, in particular such that the main emission axes of the light sources 14 are directed towards the center 10 of the receiving space 7.

[0052] Considering a section plane 15, which can form the principal axis of the spherical optical element field 5 by means of a longitudinal section, the optical element field 5 can, when considered as a whole, extend over a spherical sector with a sector angle 16 in the range of 30° to 90°, cf. Figure 3b .

[0053] The aforementioned light sources 14 can emit different colored light. It would be possible, in principle, to assign a multicolored LED cluster as a light source 14 to each optical element 6 in order to generate 6 different light colors at each optical element. Alternatively, it may also be sufficient to provide 6 different light colors at different optical elements, where, advantageously, the possible color channels are arranged in a point-mirror symmetrical arrangement opposite each other in order to generate a homogeneous energy field for the individual color channel and to facilitate sensor-based in-situ control.

[0054] For example, the optical element array 5 can be subdivided into V-shaped color channel segments, with color channel segments of the same color opposite each other and aligned in a point-mirror symmetry. For example, a green color channel segment G 1, or rather its optical elements 6, can form an upright triangle, while the opposite green segment G 2 forms an inverted triangle, cf. Figure 3a .

[0055] The optical elements 6 are configured to generate a very uniform energy field in the center of the recording space 7.

[0056] Figure 4 shows the uniform energy field distribution in the center, with, for example, partial view a of the Figure 4 The energy field distribution of the cold white channel in the center of recording space 7 is orthogonal to the central radiation axis, that is, in the Figure 3 drawn section plane 15. The grid lines in Figure 4define a 30 x 30 mm grid, from which it becomes clear that the energy field distribution is very homogeneous or uniform.

[0057] Partial view b of the Figure 4 The diagram shows the energy field distribution of the UV light channel in the center orthogonal to the central radiation axis and also illustrates a very uniform distribution.

[0058] Advantageously, the different color channels can be controlled in a dimmable manner in order to achieve multispectral excitations by switching on one or more dimmable color channels.

[0059] In the Figure 3 In the exemplary arrangement shown, in addition to the already mentioned cold white channel, a blue light channel, a green light channel and a red light channel are provided, each formed by point mirror symmetrically opposite segment areas of the spherical arrangement of the optical elements 5.

[0060] Depending on the irradiation task, other LED and optical element arrangements can also be chosen.

[0061] Advantageously, the light reactor 1 can be used to produce hydrogen, in particular by irradiating water and a substrate with light and using one or more catalysts. Sunlight can be absorbed by a so-called chromophore, i.e., a color carrier and / or a dye, whereby the chromophore transfers the light energy to the water via a water reduction catalyst. Using this energy, the water is converted into molecular hydrogen (H₂).

[0062] The chromophore mentioned above regenerates itself by producing an oxidation product from a substrate, ideally molecular oxygen (O₂). H₂ can be used as fuel, and depending on the system design, the oxidation product can be used as a raw material.

[0063] The chromophore and other substances used are capable of repeatedly carrying out this reaction, a behavior that identifies them as catalysts. The lifetime and reaction rate of the catalysts are essential factors for describing the efficiency of the system. The goal is to maximize the product of these factors, the so-called Turnover Number (TON), to achieve high molecular efficiency. The Turnover Number indicates how much hydrogen is obtained from a given quantity of the catalytic system under the influence of light.

[0064] Advantageously, [Ru 2 (bpy) 4 (trans,trans,trans-tetra-((bis-2-methoxyphenyl)phosphino)cyclobutane)](PF 6 ) 4 can be used as a chromophore (catalyst 1) and / or as a water reduction catalyst [PdCl 2 ( N,NBis((bis-2-methoxyphenyl)phosphinomethyl)ethylamine] can be used. Water and / or ascorbic acid can be used as substrates, and hydrogen and / or dehydroascorbic acid can be obtained as products.

[0065] When executing according to the Figure 2 and 3 Fourteen LEDs or LED clusters are provided as light sources. Alternatively, at least some of the light sources 14 can also be formed by the exit ends of light guides 17, which can be assigned to a respective optical element 6. How Figure 5 As shown, sunlight can be directed to the optical elements 6 of the light reactor 1 via the aforementioned light guides 17. The sunlight can be directed, for example, via a heliostat 18 and suitable deflecting optics 19 onto coupling elements, which feed the sunlight into the light guides 17 in order to then direct the light to the optical elements 6.

Claims

1. A light reactor for photochemical material production and / or treatment, comprising a receiving space (7) for receiving materials to be irradiated and a reaction vessel (8) containing such materials, a plurality of light sources (14) and a plurality of optical elements (6) which are distributed in an annular region in a plurality of rows (R1, R2, R3) around the receiving space (7), characterized in that the optical elements (6) are designed to form light bundles having main emission axes (6h) which, from row to row (R1, R2, R3), are tilted differently with respect to a longitudinal axis of the annular region and together form an irradiation space (60) constricted between two cone tips, the center of which irradiation space lies in the central region of the receiving space (7), the main emission axes (6) are distributed perpendicularly to a spherical surface which extends around the center of the receiving space (7), the optical elements (6) form an annular, spherically contoured optical element field (5) which is configured to be open towards a filling opening (3) of the light reactor (1), and the light reactor is configured as a batch reactor and includes a reactor housing (2) with said filling opening (3), which can be closed by a lid (4), for inserting the reaction vessel.

2. The light reactor according to any of the foregoing claims, wherein the light sources (14) and / or the optical elements (6) are distributed in a matrix-like or cloud-like manner, in particular in a uniform manner, on an at least approximately spherical common surface.

3. The light reactor according to any of the foregoing claims, wherein the rows (R1, R2, R3) are rotated relative to each other and thereby the optical elements (6) of adjacent rows are offset relative to each other, the offset being substantially equal to half the pitch between adjacent optical elements (6) in a row.

4. The light reactor according to any of the foregoing claims, wherein the optical elements (6) are of rotationally symmetrical design, in particular have a circular circumferential contour, and are aligned with their axes of rotational symmetry with the center of the receiving space (7).

5. The light reactor according to any of the foregoing claims, wherein the optical elements (6) are distributed point-symmetrically opposite each other with respect to the center of the receiving space (7), wherein mutually opposite optical elements (6) have mutually coaxial main emission axes (6h).

6. The light reactor according to any of the foregoing claims, wherein at least a part of the optical elements (6) is formed as a lens.

7. The light reactor according to any of the foregoing claims, wherein at least a part of the optical elements (6) is formed as a reflector.

8. The light reactor according to any of the foregoing claims, wherein differently colored light sources (14) are provided, wherein the light source (14) forms a plurality of separately actuatable color channels, wherein at least one color channel is configured to be dimmable so that a multispectral irradiation can be set, and wherein light sources of identical light color are distributed point-symmetrically opposite each other with respect to the center of the receiving space (7).

9. The light reactor according to any of the foregoing claims, wherein a sensor system (12) is provided within or on the optical element field (5) for detecting the light intensity and / or the spectrum of the irradiation in the receiving space (7), and wherein a control device is provided for variably actuating the light sources in dependence on a sensor signal of the sensor system (12).

10. The light reactor according to any of the foregoing claims, wherein the optical elements (6) are arranged closely packed one beside the other in the annular region around the receiving space (7), so that more than 50% or more than 66% or more than 75% of the surface of the annular region are occupied by the optical elements (6).

11. The light reactor according to any of the foregoing claims, wherein at least some of the light sources (14) are formed by end portions of light guides (17) or outcoupling elements connected thereto, said light guides (17) being connected to a coupling device for coupling sunlight.

12. The light reactor according to the foregoing claim, wherein the coupling device comprises a heliostat.

13. A method for synthetic material production and / or treatment in a light reactor according to any of claims 1-12, in which a material or a mixture of materials to be irradiated by light is positioned in the center of a receiving space (7), characterized in that the material or the mixture of materials is irradiated in the receiving space (7) by a plurality of light bundles which are generated separately by a plurality of light sources (14) and a plurality of optical elements (6) which are distributed in a matrix-like manner in an annular region around the receiving space (7) and are superimposed in a central region of the receiving space (7).

14. The method according to the foregoing claim, wherein a mixture of materials comprising water, a substrate and at least one catalyst is irradiated with light so that the water is converted to molecular oxygen H2, and wherein ascorbic acid is added to the water as a substrate and a chromophore, in particular Ru2(bpy)2(transe), and a water reduction catalyst, in particular PdCl2(PNPEt) are used as catalysts.

15. The use of a light reactor according to any one of claims 1 to 12 for producing molecular hydrogen H2.