Reactor for gas phase reactions

Abstract

The invention relates to a reactor for gas phase reactions, comprising an interior which is enclosed by a reactor shell and which has at least one gas inlet and at least one gas outlet, wherein at least one heating zone is located between the gas inlet and the gas outlet and the heating zone has at least one heating element and at least one gas deflection device. The gas deflection device comprises at least two regions A and B, which differ in terms of their thermal conductivity, wherein region A has a lower thermal conductivity than region B, and wherein region A is in contact with the reactor shell or wherein an insulation layer is located between region A and the reactor shell.

Description

[0001] Wa12321 P / Be

[0002] Gas-phase reaction reactor

[0003] The invention relates to a reactor for gas-phase reactions, comprising an interior enclosed by a reactor shell with at least one gas inlet and at least one gas outlet, wherein at least one heating zone is located between the gas inlet and the gas outlet, and the heating zone comprises at least one heating element and at least one gas deflection device. The gas deflection device comprises at least two regions A and B, which differ in their thermal conductivity, wherein region A has a lower thermal conductivity than region B, and wherein region A is in contact with the reactor shell or wherein an insulating layer is located between region A and the reactor shell.

[0004] Polycrystalline silicon (polysilicon) is the starting material for the production of single-crystal silicon via crucible pulling (Czochralski process) or zone melting (float zone process). Single-crystal silicon can be used in the semiconductor industry in the form of wafers for the manufacture of electronic components (chips). Furthermore, polysilicon is required for the production of multicrystalline silicon via ingot casting. Multicrystalline silicon can be used for the manufacture of solar cells.

[0005] Polysilicon can be produced by the Siemens process – a chemical vapor deposition process. In this process, thin silicon filament rods are heated by direct electric current in a reactor (Siemens reactor), and a reaction gas containing a silicon-containing component and hydrogen (H₂) is introduced. The silicon-containing component can be monosilane (SiH₄) or a halosilane of the general type Wa12321P / Be

[0006] 2

[0007] Composition SiH n X 4-n (n = 0, 1, 2, 3; X = Cl, Br, I) are used. This is usually a chlorosilane or chlorosilane mixture, especially trichlorosilane (SiHCl, TCS). The design of a typical Siemens reactor is described, for example, in US 2009 / 0136408 Al.

[0008] The production of polysilicon using the Siemens process based on TCS typically results in large quantities of silicon tetrachloride (STC):

[0009] 4SiHCl3— > Si + 3SiCl4 + 2H2 (Formula 1)

[0010] STC can be converted back to TCS by reduction with H₂, particularly using two known methods. The first method, the so-called low-temperature conversion (LTC), is carried out in the presence of one or more catalysts and is described, for example, in US 2002 / 0044904 Al. LTC is essentially the reverse reaction of Formula 1. Since the presence of catalysts (e.g., Cu) can negatively affect the purity of the TCS and thus the deposited polysilicon, a second method, the so-called high-temperature conversion (HTC), was developed (Formula 2).

[0011] SiCl4+ H2— > SiHCls + HCl (Formula 2)

[0012] HTK is an endothermic process in which product formation is equilibrium-limited. Temperatures of at least 400°C are required to produce significant quantities of TCS. These high temperatures place stringent demands on the choice of reactor materials. Furthermore, the materials must also withstand a corrosive atmosphere of Wa12321 P / Be.

[0013] 3

[0014] They must be resistant to H2, HCl and chlorosilanes. In addition, they usually have to withstand increased pressure.

[0015] Therefore, devices for carrying out high-temperature carbonization (HTC) typically consist of a pressure-bearing reactor shell within which, in the high-temperature range, components made primarily of ceramics such as SiC and / or carbon-based components such as graphite are used. The use of SiC ceramics has proven particularly advantageous, as it extends the service life of the reactors and results in a low input of carbon compounds into the product. This is described, for example, in EP 1 454 670 Al.

[0016] From an energy perspective, it can be advantageous to heat the reactant gas in countercurrent flow with the product gas, as described in US 2007 / 0073075 Al. The heat exchanger for this can be integrated into the reactor shell. To better utilize the heat output of the heaters at high, economical reactor throughputs, multiple deflections of the gas flow in the so-called hot gas region (also referred to as gas flow meandering) are frequently implemented, as described in US 2014 / 0105804 Al. This deflection is achieved by components mounted on the reactor shell, particularly the base plate. Despite the commonly used insulation (e.g., graphite felt), meandering gas flows result in a significant heat input into the reactor shell via the gas deflection devices.This is disadvantageous from both an energy perspective (heat loss to the outside) and a safety perspective (wear and tear due to increased stress on the reactor containment). Wa12321 P / Be.

[0017] 4

[0018] The aforementioned disadvantages led to the problem underlying the invention, namely to provide a reactor for gas phase reactions, such as the conversion of STG to TCS, in which energy loss and wear are reduced to a minimum.

[0019] This problem is solved by a reactor for gas-phase reactions, comprising an interior enclosed by a reactor shell with at least one gas inlet and at least one gas outlet, wherein at least one heating zone is located between the gas inlet and the gas outlet, and the heating zone has at least one heating element and at least one gas deflection device. The reactor is characterized in that the gas deflection device comprises at least two regions A and B, which differ in their thermal conductivity, wherein region A has a lower thermal conductivity than region B, and wherein region A is in contact with the reactor shell or wherein at least one insulating layer is located between region A and the reactor shell.

[0020] Preferably, the reactor is suitable for temperatures from 200 to 2000 °C, particularly preferably from 250 to 1600 °C, and especially from 350 to 1500 °C.

[0021] According to a preferred embodiment, the reactor is for the reaction of chlorosilanes and H2, preferably in a temperature range of 400 to 1600 °C, particularly preferably from 500 to 1500 °C, and especially from 600 to 1400 °C.

[0022] The term "being in contact" is intended to refer to a direct (surface, load-bearing, supporting) connection without intermediate Wa12321 P / Be

[0023] 5 layers can be understood, for example by contact (via the contact pressure of the mass of the component), screwing, riveting, welding, so that heat conduction from the gas deflection device to the reactor shell and vice versa is ensured.

[0024] The gas (reaction gas) can be heated before entering the heating zone, for example by means of heat exchangers in cross-flow or counter-flow configurations. Generally, the gas can also be heated before entering the reactor, in which case the heat exchangers are located outside the reactor.

[0025] In addition to a heating zone, the reactor can have at least one reaction zone, although a precise spatial separation between the heating zone and the reaction zone is usually not possible. Typically, the reaction zone is located more towards the center of the reactor and is surrounded by the heating zone.

[0026] In a preferred embodiment, the reactor is cylindrical and has a bottom, a lid, and a shell. In this embodiment, the heating zone is typically arranged circularly around the reaction zone in the center of the reactor, with the gas usually flowing in a meandering pattern (through the gas deflection devices) from the reactor shell towards the center. The heating elements in the heating zone are preferably electric resistance heaters.

[0027] Region A can have a thermal conductivity of 0.1 to 50 W / (m*K), preferably 0.5 to 40 W / (m*K), particularly preferably 1 to 30 W / (m*K), and especially 2 to 10 W / (m*K). Wa12321 P / Be

[0028] 6

[0029] The area B preferably has a thermal conductivity of 50 to 400 W / (m*K), particularly preferably of 100 to 350 W / (m*K), especially of 125 to 300 W / (m*K).

[0030] The difference in thermal conductivity between areas A and B is preferably at least 20 W / (m*K), particularly preferably at least 40 W / (m*K), and especially at least 60 W / (m*K).

[0031] The aforementioned values ​​for thermal conductivities are usually specified by the manufacturers in the material data sheets and can be determined, for example, using a laser flash method (e.g., DIN EN ISO 18755). Unless otherwise specified, the stated values ​​refer to a temperature of 20 °C and are determined on compact material. For anisotropic thermal conductivities, i.e., direction-dependent thermal conductivities, the minimum thermal conductivity is meant. According to the invention, the material is generally oriented such that heat transfer towards the reactor wall is minimized.

[0032] For comparison, the thermal conductivity of region A at a temperature of 500 °C is typically 1 to 50 W / (m*K), preferably 2 to 40 W / (m*K), particularly preferably 3 to 30 W / (m*K), and especially preferably 5 to 20 W / (m*K).

[0033] The thermal conductivity of region B at a temperature of 500 °C is typically 70 W / (m*K) or higher. Wa12321P / Be

[0034] 7

[0035] In a preferred embodiment, area A has a compressive strength of 10 to 500 MPa, preferably 50 to 400 MPa, and particularly preferably 100 to 250 MPa.

[0036] In general, the compressive strength of area A can also exceed 500 MPa; however, such materials are usually not economically viable. For example, some ceramics exhibit compressive strengths of 2000 to 2500 MPa. Compressive strength can be determined according to ASTM D695-02a.

[0037] Region A preferably has a tensile strength of 10 to 500 MPa, particularly preferably 20 to 350 MPa, and especially 40 to 250 MPa. Generally, the tensile strength of region A can also exceed 500 MPa. The tensile strength can be determined according to ASTM D638-03.

[0038] Furthermore, area A is preferably characterized by a coefficient of thermal expansion of 0.1 to 50*10~ 6 K -1 , especially preferred from 0.2 to 10*10~ 6 K -1 , especially from 0.5 to 8*10~ 6 K -1 , based on a temperature range of 20 to 1000°C. The coefficient of thermal expansion can be determined, for example, according to DIN EN ISO 17562.

[0039] Region A preferably comprises a material selected from the group consisting of graphite, carbon fiber materials, carbon-based fiber composites, in particular carbon fiber reinforced carbon (CFG), and combinations thereof. Region A may also consist of such a material.

[0040] The graphite can be infiltrated graphite (e.g., phenolic resin-infiltrated graphite or silicon-filtered graphite), carbon fiber-reinforced graphite, and combinations Wa12321 P / Be

[0041] 8. The area A particularly preferably comprises CFG and / or SiC-coated CFG, or consists of it.

[0042] Area A can generally also include or consist of a ceramic.

[0043] The thermal conductivity is the key factor in selecting the materials for areas A and B.

[0044] Preferably, area A does not include ceramic materials.

[0045] Furthermore, it may be preferred that region A comprises an anisotropic material, in particular that it consists of such a material. Typical anisotropic materials are carbon-based fiber composites and CFG.

[0046] In a particularly preferred embodiment, area A consists of CFG. The CFG can have several layers, which are usually arranged one above the other opposite the initial direction of main force action, preferably at an angle of inclination of -45° to 45°, particularly preferably from -35° to 35°, and especially from -25° to 25°.

[0047] The inclination angle is defined as the angle of a position relative to a horizontal, where the horizontal corresponds to the contact surface with the reactor shell or the insulation layer. This usually corresponds to the initial principal force direction.

[0048] Preferably, area A is characterized by a smaller wall thickness than area B. Wa12321P / Be

[0049] 9

[0050] Region A preferably has a wall thickness dA that corresponds to 3 to 50%, preferably 4 to 30%, and particularly preferably 6 to 25% of the wall thickness da of region B. For example, dA can be in a range of 6 to 15 mm and da in a range of 60 to 100 mm.

[0051] Preferably, section A has a length LA of 0.1 to 20%, preferably 0.5 to 10%, and particularly preferably 1 to 5%, of the total length LG of the gas deflection device, wherein LG is the sum of the length LB of section B and LA. For example, LA can have a length of 70 to 120 mm and LB a length of 2300 to 3500 mm, resulting in a length of LG of 2370 to 3620 mm.

[0052] Preferably, the region A has a length LA of 0.1 to 20%, preferably 0.25 to 10%, and particularly preferably 0.5 to 5%, of the reactor height HR, where HR corresponds to the height of the interior enclosed by the reactor shell. For example, LA can be 70 to 120 mm and HR 8000 to 14000 mm.

[0053] Regions A and B are preferably connected to each other via a common edge, particularly without any breaks. In other words, region A preferably has the same cross-sectional shape as region B, although there may be differences in the respective wall thicknesses. However, the common edge may be interrupted by openings in region B that are necessary for gas passage.

[0054] In another embodiment, area A can be divided into several support elements. Preferably, the support elements are column-like. In particular, they feature Wa12321 P / Be

[0055] 10. The support elements have a round or rectangular cross-section. The support elements are preferably arranged equidistantly. Particularly preferably, area A consists of at least two support elements.

[0056] For example, hollow cylinders and / or cylinders made of CFG can be used as support elements for area A. The spaces between the support elements can be sealed with insulation (e.g., graphite felt or graphite foil) to prevent gas penetration.

[0057] For example, area A can comprise (or consist of) several hollow cylinders and / or cylinders with anisotropic structure, which absorb the necessary loads in the axial direction and thus support the weight of the gas deflection device and possibly other internal components (e.g. heat exchanger blocks).

[0058] Region B preferably comprises a material selected from the group consisting of aluminum oxide, zirconium oxide, silicon carbide, in particular nitride-bonded silicon carbide, silicon nitride, graphite, in particular SiC, silicon carbide-coated graphite and silicon carbide-filtered graphite, and combinations thereof. In particular, region B may consist of such a material.

[0059] In principle, areas A and B differ in the type and / or structure (or orientation) of their materials, whereby an orientation of, for example, a layered material in section A with a layering of the layers essentially perpendicular to the direction of the main force is preferred. Wa12321 P / Be

[0060] 11

[0061] Area A and / or area B may have a coating. Such a coating could be, for example, SiC.

[0062] Preferably, areas A and B are connected to each other via a force-fit or a form-fit connection. The connection can be achieved, for example, by gravity with flat contact surfaces or via tongue-and-groove connections or similar plug-in connections. In particular, areas A and B are connected to each other in a gas-tight and detachable manner.

[0063] Typically, area A carries the weight of area B and possibly other components, such as additional heat exchanger blocks.

[0064] The insulating layer preferably comprises a material selected from the group consisting of graphite felt, graphite foil, ceramic fiber, glass fiber, mica, aluminosilicates, and mixtures thereof. In particular, the insulating layer can consist of such a material. The insulating layer is most preferably made of graphite felt, ceramic fibers, or mica.

[0065] The height (extent perpendicular to the base plate) of the insulation layer is usually in the range of 5 to 300 mm, preferably 10 to 250 mm, and particularly preferably 30 to 230 mm. A typical value is 100 mm.

[0066] By reducing the energy input to the insulation layer, not only is the overall energy loss of the reactor reduced, but the durability of the insulation layer is also increased due to the lower stress, leading to longer reactor operating times. Wa12321 P / Be

[0067] 12

[0068] The gas deflection device preferably has openings for gas passage. These openings are particularly preferably arranged only in area B.

[0069] The openings can be material recesses of any geometry and size (e.g., circles, slots, rectangles). The openings can be fitted with perforated metal sheets or wire mesh, for example, to limit their gas permeability.

[0070] Preferably, the gas deflection device has a cylindrical shape.

[0071] The gas deflection device is preferably arranged concentrically with respect to the cross-section of the reactor shell. Thus, a reactor with a cylindrical reactor shell (and therefore a round base plate) can have one to five concentric gas deflection devices. These can be arranged equidistantly or at different distances from each other. A spiral design of the gas deflection device is also conceivable. Preferably, the gas deflection devices are positioned freely on a base plate of the reactor.

[0072] The at least one heating element for heating the gas flow is usually arranged in the heating zone between the gas deflection devices and is preferably directly surrounded by gas, thus ensuring optimal heat transfer.

[0073] The exact positioning of the heating elements is generally irrelevant for the feasibility of the invention. A rotationally symmetrical arrangement around a center point is common (Wa12321P / Be).

[0074] 13 of a reactor base plate. A heating element may also be provided in the center of the reactor.

[0075] In principle, the heating elements can also be positioned outside the interior, although this results in reduced heat input, but also in less stress on the heating elements.

[0076] Another aspect of the invention relates to the use of the reactor according to the invention for the hydrogenation of chlorosilanes at a temperature of 800 to 1600°C.

[0077] A process for the hydrogenation of chlorosilanes at a temperature of 800 to 1600°C is described accordingly, wherein the process is carried out in the reactor according to the invention. In particular, the process is an HTK (see Formula 2).

[0078] Preferably, the chlorosilanes are a mixture of dichlorosilane (0 to 8 mol%), TCS (0 to 6 mol%), and STC (86 to 100 mol%), where the values ​​in parentheses refer to the chlorosilane content. The H₂ supplied for hydrogenation can contain 0 to 5 mol% HCl, 0 to 3 mol% CH₄, 0 to 5 mol% N₂, and 0 to 1 mol% CO₂.

[0079] It may be preferable, for example, to supply methane and / or N2 within the specified composition ranges, as this can further increase the reactor service life in accordance with the state of the art (W015140027 or US2019322534). Wa12321P / Be

[0080] 14

[0081] The molar ratio of H2 to chlorosilanes is in the range of 10:1 to 1:1, preferably from 5:1 to 1.25:1, particularly preferably from 2.5:1 to 1.5:1.

[0082] Surprisingly, the hydrogenation of chlorosilanes has shown that the material used in section A can exhibit lower chemical resistance than the material used in section B of the gas deflection device. This was determined by measuring the corrosion rates of the respective materials after a specific reactor operating time. The material resistance can be determined as described in US 2007 / 0073075 Al. This allows for the particularly cost-effective use of materials for section A that have not undergone an additional coating process with SiC (neither in-situ nor ex-situ).

[0083] Thus, the use of a material selected from the group including graphite, carbon composites, carbon-based fiber composites, in particular CFG, and combinations thereof, surprisingly did not lead to a reduced service life of the reactor in area A compared to a reference reactor in which area A consisted of SiC, or in which the entire gas deflection device was made of SiC.

[0084] Furthermore, the use of these materials in area A does not typically lead to an increased proportion of reaction products in the reaction product that are formed by the reaction of carbon, such as methyldichlorosilane and / or methyltrichlorosilane, compared to a reactor in which the entire gas deflection device was made of SiC. Wa12321P / Be

[0085] 15

[0086] One possible explanation for this surprising effect is the low energy input into area A and the associated lower thermal stress, due to the low thermal conductivity of area A and its proximity to the (preferably cooled) reactor shell.

[0087] Fig. 1: Longitudinal section of a reactor according to the invention

[0088] Fig. 2: Detailed view of the gas deflection device

[0089] Fig. 3: Cross-section (along aa) of a reactor according to the invention

[0090] Fig. 4: Cross-section (along bb) of a reactor according to the invention

[0091] Fig. 5: Cross-section (along bb) of another

[0092] embodiment of the reactor according to the invention

[0093] Reference symbol list

[0094] 100, 200 gas phase reactor

[0095] 10 Base plate

[0096] 11 Reactor casing

[0097] 12, 212 Reactor shell

[0098] 13 Interior

[0099] 14, 214 external gas deflection device

[0100] 15, 215 medium gas deflection device

[0101] 16, 216 internal gas deflection device

[0102] 17 Area B

[0103] 18, 218 Area A

[0104] 19 lids

[0105] 20 heat exchangers

[0106] 21 Breakthrough

[0107] 22, 222 Heating element

[0108] 23 Heating zone Wa12321P / Be

[0109] 24 Center of the interior

[0110] 25 Gas inlet

[0111] 26 Gas outlet

[0112] 27 edge

[0113] 228 Insulation

[0114] 229 Space (between areas A)

[0115] Figure 1 shows the lower part of a cylindrical gas-phase reactor 100 in longitudinal section. This part has a reactor shell 12, which is divided into a reactor jacket 11 and a base plate 10, thus enclosing a pressure-bearing interior 13. The reactor lid, which is usually also part of the reactor jacket 11, is not shown here. An outer, middle, and inner gas deflection device 14, 15, 16 rests on the base plate 10. The gas deflection devices 14, 15, 16 are each cylindrical and arranged concentrically. Each of the gas deflection devices 14, 15, 16 consists of a region B 17 and a region A 18, with only region A 18 being in contact with the base plate 10. The area A 18 consists in particular of multi-layered CFG, wherein there is an inclination angle of -25 to +25° between the individual layers, in a particularly preferred embodiment with horizontal layering at -10 to +10°.The thermal conductivity perpendicular to the layer plane, for example, has a value of 8 W / (m*K) at 20°C and a value of 10 W / (m*K) at 500°C. Area B 17 consists, for example, of SiC. The thermal conductivity in this area is...

[0116] B, for example, has a value of 125 W / (m*K) at 20°C and a value of 70 W / (m*K) at 500°C.

[0117] To ensure a meandering gas flow, area B 17 of the gas deflection devices 14, 15, 16 is each provided with openings 21. The openings 21 Wa12321P / Be

[0118] The openings 21 of the middle gas deflection device 15 are not located adjacent to area A 18, but rather adjacent to a cover 19 that seals the gas deflection devices 14, 15, 16 gas-tight from above. The load-bearing capacity of components located above, such as the indicated heat exchanger 20, rests on the cover 19. Thus, sections A support the load of the entire structure and transfer it to the base plate 10.

[0119] Eight heating elements 22 (see Fig. 2) are arranged between the outer and middle gas deflection devices 14, 15, defining a heating zone 23. Generally, more heating elements (e.g., 18 pairs or 36 individual elements) can be arranged here. Furthermore, heating elements can be arranged between the outer and inner gas deflection devices 14, 16 (not shown).

[0120] Gas flowing in through a gas inlet 25, which may be preheated via a heat exchanger, flows around the heating elements 22 and meanders through the openings 21 into the center 24. From there, the reaction products are directed towards the gas outlet 26. The center 24 may correspond to a reaction zone, although a sharp separation between the heating zone and the reaction zone is generally not possible.

[0121] The upper part of the reactor, not shown, typically includes additional heat exchanger units and possibly gas distributors to optimize heat transfer. This allows, as described in US 2014 / 0105804 Al, the energy Wa12321 P / Be

[0122] 18 efficiency is further increased and the additional heating energy to be supplied via the heating elements 22 is minimized.

[0123] Figure 2 shows a detailed view of the gas deflection devices 14, 15, which each have the same length LG (typically 2500 mm). The length LA of section A is only 4% of the length LG (typically 100 mm). Furthermore, section A 18 has a smaller thickness ÖA than section B 17 (da) (typically dA = 10 mm and dß = 60 mm). In particular, materials without an additional protective SiC layer are used for section A 18. Despite the small thickness ÖA of section A 18, it can support the mass of the overlying structure, which typically consists of at least 5-15 heat exchanger blocks.

[0124] Despite these stresses and the fact that the SiC coating of section A 18 is reduced compared to the prior art, the reactor design according to the invention achieves unchanged or even longer operating times, while the energy consumption of the design according to the invention is even reduced. The small thickness ÖA of section A 18 further reduces heat dissipation to the cooled reactor shell 12 and therefore requires lower material costs. Materials for section A that have not undergone an additional coating process with SiC (neither in-situ nor ex-situ) can be used with particular economic advantage. Materials not infiltrated with SiC are particularly preferred for section A, since these non-infiltrated materials are characterized by an optimum balance between service life (corresponding to reactor operating time), thermal conductivity (corresponding to energy loss), and manufacturing costs. Wa12321 P / Be

[0125] 19

[0126] Figure 3 shows a cross-section along the section line aa from Figure 1, which reveals the concentric arrangement of the gas deflection devices 14, 15, 16 (only area B 17 is visible due to the position of the section line aa) and the arrangement of the heating elements 22.

[0127] Figure 4 shows a cross-section along section line bb from Figure 1. Due to the position of section line bb, only region A 18 is visible, which has a thinner wall compared to region B 17 (see Fig. 2). Regions A and B 18, 17 are in contact with each other via a common edge 27. This contact is typically planar and gas-tight due to the high contact pressure.

[0128] Figure 5 shows a cross-section of another embodiment of a gas-phase reactor 200, the cross-section passing through region A 218 of the gas deflection devices 214, 215, 216. Region A 218 of the inner gas deflection device 216 comprises three column-shaped support elements with a circular cross-sectional area, which support the weight of region B, which is not visible due to the section line. To prevent gas passage, the spaces between the column-shaped support elements are gas-tightly sealed with insulation 28. The insulation 28 consists of graphite felt and / or graphite foil. Region A 218 of the middle gas deflection device 215 comprises four column-shaped support elements with a square cross-sectional area. Region A 218 of the outer gas deflection device 214 also comprises four column-shaped support elements with a rectangular cross-sectional area. Regarding the spaces 229, reference can be made to the description above.

Claims

Wa12321 P / Be 20 Patent claims 1. Reactor for gas-phase reactions, comprising an interior enclosed by a reactor shell with at least one gas inlet and at least one gas outlet, wherein at least one heating zone is located between the gas inlet and the gas outlet and the heating zone has at least one heating element and at least one gas deflection device, characterized in that the gas deflection device comprises at least two areas A and B which differ in their thermal conductivity, wherein area A has a lower thermal conductivity than area B, and wherein area A is in contact with the reactor shell or wherein an insulating layer is located between area A and the reactor shell.

2. Reactor according to claim 1, characterized in that the region A has a thermal conductivity of 0, 1 to 50 W / (m*K) , preferably from 0.5 to 40 W / (m*K) , particularly preferably from 1 to 30 W / (m*K) , particularly preferably from 2 to 10 W / (m*K) .

3. Reactor according to claim 1 or 2, characterized in that the region B has a thermal conductivity of 50 to 400 W / (m*K), preferably of 100 to 350 W / (m*K), particularly preferably of 125 to 300 W / (m*K).

4. Reactor according to one of the preceding claims, characterized in that the difference in thermal conductivity between regions A and B is at least 20 W / (m*K), preferably at least 40 W / (m*K), particularly preferably at least 60 W / (m*K). Wa12321P / Be 21 5. Reactor according to one of the preceding claims, characterized in that the region A comprises a material selected from the group consisting of graphite, carbon composite materials, carbon-based fiber composite materials, in particular carbon fiber reinforced carbon, and combinations thereof.

6. Reactor according to one of the preceding claims, characterized in that the region A comprises an anisotropic material, preferably consisting of such a material.

7. Reactor according to one of the preceding claims, characterized in that the region A consists of carbon fiber reinforced carbon, wherein the carbon fiber reinforced carbon has several layers arranged at an angle of inclination of -45 to 45°, preferably of -35 to 35°, particularly preferably of -25 to 25°.

8. Reactor according to one of the preceding claims, characterized in that the area A has a wall thickness dA which corresponds to 3 to 50%, preferably 4 to 30%, particularly preferably 6 to 25% of a wall thickness da of the area B.

9. Reactor according to one of the preceding claims, characterized in that the region A has a length LA which is 0.1 to 20%, preferably 0.5 to 10%, particularly preferably 1 to 5%, of a total length LG of the gas deflection device, wherein LG is the sum of a length LB of region B and LA. Wa12321 P / Be 22 10. Reactor according to one of the preceding claims, characterized in that the area A is divided into several support elements.

11. Reactor according to one of the preceding claims, characterized in that the region B comprises a material selected from the group consisting of aluminium oxide, zirconium oxide, silicon carbide, in particular nitride-bonded silicon carbide, silicon nitride, graphite, in particular silicon carbide, silicon carbide-coated graphite and silicon carbide-inf titrated graphite, and combinations thereof.

12. Reactor according to one of the preceding claims, characterized in that the insulating layer consists of a material selected from the group consisting of graphite felt, graphite foil, ceramic fiber, glass fiber, mica, aluminosilicates, preferably graphite felt or ceramic fibers.

13. Reactor according to one of the preceding claims, characterized in that the gas deflection device has openings for the gas passage.

14. Reactor according to one of the preceding claims, characterized in that the gas deflection device has a cylindrical shape.

15. Use of a reactor according to at least one of the preceding claims for the hydrogenation of chlorosilanes at a temperature of 800 to 1600 °C.

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