Method for producing trichlorosilane having a structure-optimized silicon particle

Abstract

The present invention relates to compounds of general formulas 1 and 2: H n SiCl 4-n (1) H m Cl 6-m Si2(2), where: n is 0 to 3, and m is 0 to 4 a method for producing, in a fluidized bed reactor, a chlorosilane selected from Here, the hydrogen chloride-containing reaction gas reacts with the silicon-containing microparticle contact mass at a temperature of 280°C to 400°C, The operational granulate, understood here to mean the operational granulate or granulated mixture introduced into the fluidized bed reactor, comprises at least 1% by weight of silicon-containing particles represented by a structural parameter S, where S has a value of at least 0 and is calculated as follows: TIFF2022534930000005.tif15155where, φ S is the symmetrically loaded sphericity factor, ρ SD is the packing density [g / cm 3 ] and ρ F is the average particle solid density [g / cm 3 ].

Description

Technical Field

[0001] The present invention relates to a method for producing chlorosilane from a particulate silicon contact mass containing a hydrogen chloride-containing reaction gas and structurally optimized silicon particles in a fluidized bed reactor.

Background Art

[0002] The production of polycrystalline silicon as a starting material for the manufacture of chips or solar cells is typically carried out by the decomposition of its volatile halogen compounds, in particular trichlorosilane (TCS, HSiCl3).

[0003] Polycrystalline silicon (polysilicon) may be produced in rod form by the Siemens process, where the polysilicon is deposited on a heated filament rod in a reactor. The process gas used is typically a mixture of TCS and hydrogen. Alternatively, polycrystalline silicon granules may be produced in a fluidized bed reactor. The silicon particles are fluidized in the fluidized bed by an air stream, where this stream is heated to a high temperature via a heating device. The addition of a silicon-containing reaction gas such as TCS results in a pyrolysis reaction on the hot particle surface, thereby increasing the particle diameter.

[0004] The production of chlorosilane, in particular TCS, can essentially be carried out by three processes according to WO2016 / 198264A1, which are based on the following reactions: (1) Si + 3HCl --> SiHCl3 + H2 + by-products (2) Si + 3SiCl4 + 2H2 --> 4SiHCl3 + by-products (3) SiCl4 + H2 --> SiHCl3 + HCl + by-products The hydrogen chloride addition (HC) according to reaction (1) is the addition of hydrogen chloride (HCl) in a fluidized bed reactor to silicon (typically metallic silicon (Si mgmakes it possible to produce chlorosilanes, where this reaction proceeds as an exothermic reaction. This generally results in TCS and STC (silicon tetrachloride) as the main products.

[0005] A further option for producing chlorosilanes, in particular TCS, is the thermal conversion of STC with hydrogen in the gas phase, with or without a catalyst, according to reaction (3).

[0006] The low-temperature conversion (LTC) according to reaction (2) is a weakly endothermic process and is typically carried out in the presence of a catalyst (for example, a copper-containing catalyst or a catalyst mixture). LTC can be carried out in a fluidized bed reactor in the presence of Si mg at high pressure (0.5 - 5 MPa) and at a temperature between 400 °C and 700 °C. The uncatalyzed reaction mode can be enabled by using Si mg and / or by the addition of HCl to the reaction gas. However, other product distributions may occur and / or a lower TCS selectivity than the catalyzed variant may be achieved.

[0007] The high-temperature conversion according to reaction (3) is an endothermic process. This process is typically carried out in a reactor at high pressure and at a temperature between 600 °C and 1200 °C.

[0008] The demand for silicon regarding the chemical composition and particle size distribution for the synthesis of chlorosilanes has been relatively well studied; in contrast, the structural assembly of silicon particles and its influence on the reaction with halide-containing reaction gases has so far only been described with respect to the intermediate phase - in particular MRDS (Muller - Rochow direct synthesis). So far, it has not been described how all three influencing factors should interact, especially for a high-yield chlorosilane production process.

[0009] Accordingly, DE4303766A1 discloses a process for producing methylchlorosilanes from silicon and chloromethane in the presence of a copper catalyst and optionally a promoter, wherein the production rate of the individual methylchlorosilanes is controlled through the structure of the silicon, based on the surface area of the silicon used, wherein this process is characterized in that silicon having the desired structure is selected according to the structure index QF, and wherein this structure index QF is measured as follows: a) cutting open a silicon test specimen to form a cut surface, b) summing the area of the precipitation of the mesophase having an elongated shape on this cut surface to create an area number A, c) summing the area of the precipitation of the mesophase having a round shape on this cut surface to create an area number B, d) creating a count described as the structure index QF from the area number A and the area number B.

[0010] The correlation between the QF of different silicon structure types and their behavior in MRDS enables the identification of the optimal structural characteristics in silicon, and thus enables the control of the selectivity and yield for the desired methylchlorosilanes in the desired direction. In this context, the term "structure" relates to the crystal size of polycrystalline silicon and also to the composition and position of the mesophases that precipitate with the silicon from the main impurities, such as Al, Ca, Fe, and Ti, during the processes of cooling and solidification. Accordingly, this document only expands the knowledge regarding the requirements in silicon with respect to chemical composition for the synthesis of organochlorosilanes mentioned previously. Furthermore, this type of operation requires the purchase of silicon types tailored to the purpose and / or the operation of corresponding in-house silicon production, as well as a huge analytical effort. The structure index QF may be used to improve the structural parameter S of the present invention, but this is not necessarily required. Furthermore, the application of the MRDS findings to HC may be limited, if at all.

[0011] DE3938897A1 discloses a process for producing trichlorosilane by reacting silicon powder with HCl gas at a temperature between 280 °C and 300 °C in a fluidized bed / moving bed reactor, which is characterized by the use of silicon powder obtained by gas atomization of molten silicon. In this process, the silicon powder preferably has a particle size between 50 and 800 μm. This results in a higher HCl conversion and reduced by-product formation compared to conventional processes, with an increase in HCl conversion from 90 - 95% to 97 - 98% and a reduction in STC in the product gas to 3% - 5% being reported. Since the method of measurement has not been reported, no data on the composition of the product gas is provided, and it is not clear whether the latter are values in weight percent, mole percent or volume percent, and it is not possible to measure to what extent this process is optimized compared to the conventional processes mentioned. Apart from the range limits for the particle size of the silicon powder, no details of this powder are specified.

[0012] In addition to the high formation of STC and solvents with higher melting points, the process costs increase in principle as a result of unreacted HCl and unreacted silicon.

[0013] In the production of chlorosilanes, it is known that a fluidized bed reactor is used to specifically remove the fraction of fine particles of silicon particles. For example, Lobusevich, N.P et al, “Effect of dispersion of silicon and copper in catalysts on direct synthesis”, Khimiya Kremniiorganich.Soed.1988, 27 - 35 describes the operating granulates for silicon in the range of 70 - 500 μm, where 70 μm is the minimum and 500 μm is the maximum particle size (particle size limit or range limit), and the values correspond to the diameter. Lobusevich et al reported that when selecting the contact mass particle size for the synthesis of methylchlorosilane, ethylchlorosilane and TCS, the interaction between the solid and the gas must be considered in order to achieve the maximum stability and efficiency of the process. Therefore, in the synthesis of TCS (at 400 °C), the operating granulates of 2 - 3 mm resulted in a decrease in the reaction rate of about 25% - 30% compared to the operating granulates of 70 - 500 μm. When a copper-containing catalyst was added, the reaction by silicon particles in the 2 - 3 mm implementation fraction occurred as early as 250 °C. The reaction rate is comparable to that of the uncatalyzed variant at 400 °C. In both cases (both the catalyzed and uncatalyzed variants), an increase in the silicon particle size results in an increase in TCS selectivity and a reduction in the formation of poly(chloro)silanes (high melting point solvents).

[0014] A higher reaction temperature is required to accelerate the reaction, and a higher gas velocity is required to create a fluidized bed. Therefore, an increase in particle size generally requires a greater energy cost. In the context of a polydisperse particle mixture, Lobusevich et al. reported that the use of the smaller silicon particle fraction enhances the activity of silicon due to the increased surface area. However, the use of the smaller silicon particle fraction is difficult because the discharge of silicon particles from the reactor increases and particle aggregation can occur. Therefore, according to Lobusevich et al., it is advantageous to reduce the width of the particle size distribution of the silicon particles used and increase the average particle size, despite the higher energy cost.

Prior Art Documents

Patent Documents

[0015]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0016]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0017] The present invention aims to provide a particularly economical process for the production of chlorosilanes via HC.

Means for Solving the Problem

[0018] The present invention provides a method for producing chlorosilanes selected from general formulas 1 and 2: H n SiCl 4-n (1), H m Cl 6-m Si2(2), wherein, n is from 0 to 3, and m is from 0 to 4 in a fluidized bed reactor, wherein the hydrogen chloride-containing reaction gas reacts with a particulate contact mass containing silicon at a temperature of 280°C to 400°C, wherein the operating granulate, which is understood to mean the granulate or granulation mixture introduced into the fluidized bed reactor, contains silicon-containing particles represented by at least 1% by mass of the structural parameter S, where S has a value of at least 0 and is calculated as follows: wherein

[0019]

Number

[0020] Surprisingly, it has been found that the production of chlorosilanes in a fluidized bed reactor can be carried out particularly economically when silicon-containing particles having specific structural properties are used in the operating granulate. This effect has been found to be significantly detectable even for structurally optimized silicon particles S in a proportion exceeding 1% by mass in the operating granulate. The precise use of such silicon particles S has been described in Lobusevich, N.P et al, “Effect of dispersion of silicon and copper in catalysts on direct synthesis”, Khimiya Kremniiorganich.Soed. 1988, 27 - 35 to result in a long - lasting reduction of the dust fraction below 70 μm in the production process due to the reduction of dust formation by friction. This brings several advantages over the prior art: ● Higher TCS selectivity ● Reduction of the formation of high - melting - point solvents ● Higher utilization rate of HCl ● Higher silicon utilization rate (reduction of losses through dust emission) ● Obtaining an improved homogeneous contact mass in terms of particle size distribution and an improvement in the fluid - mechanical properties of the fluidized bed ● Reduction of blockage and / or interference of plant parts due to agglomeration of finely divided particles, i.e., the dust fraction (particles having a particle size below 70 μm) ● Improved transportability of the particle mixture ● Extension of the reactor operating time (higher plant performance) due to reduced abrasion

[0021] The preconception of Lobusevich et al., that the TCS selectivity in chlorosilane formation increases only for granulated mixtures with a large average particle size, is also overcome. This is because, according to the present invention, particles S having a structural parameter S of 0 or more preferably have a smaller average particle size than particles having a structural parameter S of less than 0, and thus the average particle size of the granulated material for operation becomes smaller. Surprisingly, the adverse effects expected for the reduction of the average particle size according to the present knowledge in the art, such as an increase in the release of relatively small silicon particles from the reactor and the occurrence of an agglomeration effect, were not observed. In contrast, the process according to the present invention has shown an improvement in the flow characteristics of the contact mass in addition to the advantages already mentioned.

Brief Description of the Drawings

[0022]

Figure 1

Embodiments for Carrying Out the Invention

[0023] The term "granulated material" is understood to mean a mixture of silicon-containing particles that can be produced, for example, by so-called spraying or atomization of a silicon-containing melt and / or by pulverization of a silicon mass by a crushing and milling plant. The silicon mass preferably has an average particle size of less than 10 mm, particularly preferably less than 20 mm, and in particular less than 50 mm. The granulated material may be classified into fractions, essentially by sieving and / or screening.

[0024] A mixture of different granulated materials may be described as a granulated mixture, and the granulated materials forming the granulated mixture may be described as granulated fractions. The granulated fractions may be graded with respect to one or more properties of the fractions, for example, into a coarse granulated fraction and a fine granulated fraction. In principle, the granulated mixture may be graded into more than one granulated fraction in a given corresponding fraction.

[0025] The operating granulate represents the operating granulate or granulation mixture introduced into the fluidized bed reactor.

[0026] Symmetry Aggravation Sphericity factor φ s is the product of the symmetry factor and the sphericity. Both shape parameters are measured by dynamic image analysis in accordance with ISO 13322, where the values obtained represent the volume Aggravation average of a specific sample of a particle mixture suitable for the operating granulate.

[0027] The symmetry of particle S Aggravation sphericity factor is preferably at least 0.70, particularly preferably at least 0.72, very preferably at least 0.75, and in particular at least 0.77, and is at most 1.

[0028] The sphericity of the particle represents the ratio between the surface area and the circumference squared of the particle image. Thus, spherical particles have a sphericity close to 1, while on the other hand, jagged and distorted particle images have a roundness close to 0.

[0029] When measuring the symmetry factor of a particle, first measure the center of gravity of the particle image. Then, particle draw a path from end to end passing through the center of gravity in each measurement direction, and measure the two resulting cutting paths. The value of the symmetry factor is calculated from the smallest ratio of these areas. For highly symmetric figures, such as a circle or a square, the value of a specific symmetry factor is equal to 1.

[0030] Further shape parameters measurable by dynamic image analysis are the width / length ratio (the horizontal / vertical measurement of the particle) and the convexity of the particle. However, since these parameters are already indirectly included in the structural parameter S in the form of the symmetry factor, they do not need to be measured in the process according to the present invention.

[0031] The packing density is defined as the density of a mixture of particulate solids (so-called bulk solids) and a continuous fluid (such as air) filling the gaps between the particles. 0 or moreThe packing density of the particle fraction of the operating granulate having the structural parameter S is preferably 0.8 to 2.0 g / cm 3 , particularly preferably 1.0 to 1.8 g / cm 3 , very preferably 1.1 to 1.6 g / cm 3 , specifically 1.2 to 1.5 g / cm 3 . The packing density is measured in accordance with DIN ISO697 via the ratio of the mass of the bulk material to the volume occupied by the bulk material.

[0032] 0 or more The average mass weighted particle solid density of the particles S of the particle fraction having the structural parameter S is preferably 2.20 to 2.70 g / cm 3 , particularly preferably 2.25 to 2.60 g / cm 3 , very preferably 2.30 to 2.40 g / cm 3 , specifically 2.31 to 2.38 g / cm 3 . The measurement of the density of the solid is described in DIN66137-2:2019-03.

[0033] 0 or more The particle fraction having the structural parameter is preferably present in the operating granulate in a mass fraction of at least 1% by mass, particularly preferably at least 5% by mass, very preferably at least 10% by mass, specifically at least 20% by mass.

[0034] The particles S having S of 0 or more preferably have a particle size parameter d that is 0.5 times to 0.9 times that of the particles having S less than 0 50 . 50

[0035] The operating granulate preferably has a particle size parameter d of 70 to 1000 μm, particularly preferably 80 to 800 μm, very preferably 100 to 600 μm, specifically 120 to 400 μm 50 .

[0036] Particle size parameter d 90 and d 10The difference from is the measured value of the width of the granulated product or granulated fraction. The ratio of the width of the granulated product or granulated fraction and each particle size parameter d 50 corresponds to the relative width. This may be used, for example, to compare particle size distributions having very different average particle sizes.

[0037] The relative width of the granulated product for operation is preferably 0.1 to 500, more preferably 0.25 to 100, particularly preferably 0.5 to 50, and specifically preferably 0.75 to 10.

[0038] The measurement of the particle size and particle size distribution may be performed in accordance with ISO 13320 (laser diffraction) and / or ISO 13322 (image analysis). The calculation of the particle size parameter from the particle size distribution may be performed in accordance with DIN ISO 9276-2.

[0039] In a further preferred embodiment, the granulated product for operation has a mass 2 surface area of 80 to 1800 cm 2 / g, preferably 100 to 600 cm 2 / g, particularly preferably 120 to 500 cm 2 / g, and specifically 150 to 350 cm Aggravation / g.

[0040] The granulation mixture of the granulated product for operation preferably has a p-modal volume Aggravation distribution density function, where p = 1 to 10, preferably p = 1 to 6, particularly preferably p = 1 to 3, and specifically p = 1 or 2. For example, a 2-modal distribution density function has two maxima.

[0041] The use as an agglomerate of a granulation mixture having a polymodal (for example, p = 5 to 10) distribution density function makes it possible to avoid a sieving effect (separation of individual particle fractions in a fluidized bed, for example, a twin fluidized bed). These effects occur particularly when the maxima of the distribution density function of the granulation mixture are far apart.

[0042] The contact mass is a granulated mixture that is in contact with the reactive gas in detail. Thus, the contact mass preferably does not contain further components. This mass is preferably a silicon-containing granulated mixture that contains, as impurities, other elements up to 5% by weight, particularly preferably up to 2% by weight, and in detail up to 1% by weight. This mass preferably typically has a purity of 98% to 99.9% Si mg and is. A typical contact mass is, for example, a composition containing 98% by weight of silicon metal, where the remaining 2% by weight generally consists mostly of elements selected from Fe, Ca, Al, Ti, Cu, Mn, Cr, V, Ni, Mg, B, C, P, and O. The contact mass may also contain elements selected from Co, W, Mo, As, Sb, Bi, S, Se, Te, Zr, Ge, Sn, Pb, Zn, Cd, Sr, Ba, Y, and Cl. The use of silicon with a lower purity of 75% to 98% by weight is also possible. However, it is preferred that the silicon metal ratio is greater than 75% by weight, preferably greater than 85% by weight, and particularly preferably greater than 95% by weight.

[0043] Some of the elements present as impurities in silicon have catalytic activity. Thus, the addition of a catalyst is not necessary in principle. However, this process may be favorably affected by the presence of a further catalyst, in particular with regard to its selectivity.

[0044] The catalyst may be one or more elements from the group comprising Fe, Cr, Ni, Co, Mn, W, Mo, V, P, As, Sb, Bi, O, S, Se, Te, Ti, Zr, C, Ge, Sn, Pb, Cu, Zn, Cd, Mg, Ca, Sr, Ba, B, Al, Y, Cl. The catalyst is preferably selected from the group comprising Fe, Al, Ca, Ni, Mn, Cu, Zn, Sn, C, V, Ti, Cr, B, P, O, Cl, and mixtures thereof. As described, these catalytically active elements are already present in silicon in certain proportions, for example, in oxidized or metallic form, as silicides or other metallurgical phases or as oxides or chlorides. The proportion depends on the purity of the silicon used.

[0045] The catalyst may be added to the operating granulate and / or the contact mass, for example, in metallic form, alloy form and / or salt form. This catalyst may, in particular, be a chloride and / or an oxide of a catalytically active element. Preferred compounds are CuCl, CuCl2, CuO or mixtures thereof. The operating granulate may further contain a promoter, for example, Zn and / or zinc chloride.

[0046] The elemental composition of the silicon and the contact mass used may be measured, for example, by X-ray fluorescence analysis (XFA), ICP-based analytical methods (ICP-MS, ICP-OES) and / or atomic absorption spectrometry (AAS).

[0047] Based on silicon, the catalyst is preferably used in a proportion of 0.1% to 20% by weight, particularly preferably 0.5% to 15% by weight, in particular 0.8% to 10% by weight, and particularly preferably 1% to 5% by weight.

[0048] The particle fraction having a structural parameter S less than 0 and the particle fraction having an S of 0 or more are preferably fed to the fluidized bed reactor as a pre-prepared granulated mixture. Any further components of the contact mass may likewise be present. The fraction of the operating granulate having a structural parameter S of 0 or more of at least 1% by weight in the proportion of the present invention results in the latter, in particular having transport properties because of better fluidization.

[0049] The particle fraction having a structural parameter S less than 0 and the particle fraction having an S of 0 or more may also be fed to the fluidized bed reactor separately, in particular via separate supply pipes and containers. The mixing then takes place, in principle, during the formation of the fluidized bed (in situ). Any further components of the contact mass may likewise be fed separately as components of either of the two particle fractions.

[0050] This process is preferably carried out at a temperature of 280°C to 400°C, particularly preferably 340°C to 360°C. The absolute pressure in the fluidized bed reactor is preferably 0.01 to 0.6 MPa, particularly preferably 0.03 to 0.35 MPa, in particular 0.05 to 0.3 MPa.

[0051] Before introduction into the reactor, the reaction gas preferably contains at least 50% by volume, preferably at least 70% by volume, particularly preferably at least 90% by volume of HCl. In addition to HCl, the reaction gas contains H2, H n SiCl 4-n (n = 0 to 4), H m Cl 6-m Si2 (m = 0 to 6), H q Cl 6-q Si2O (q = 0 to 4), (CH3) u H v SiCl 4-u-v (u = 1 to 4 and v = 0 or 1) and may further contain one or more components selected from the group consisting of CH4, C2H6, CO, CO2, O2, N2. These components may be derived from the HCl recovered in the integrated system. It is preferred that HCl and silicon be present in an HCl / Si molar concentration ratio of 5:1 to 2.5:1, preferably 4:1 to 3:1, particularly preferably 3.6:1 to 3:1, and specifically 3.4:1 to 3.1:1. HCl and the contact mass / granulation mixture or its particle fraction are continuously added such that the above ratio is established during the reaction, specifically.

[0052] The reaction gas is H n SiCl 4-n (n = 0 to 4), H m Cl 6-m Si2 (m = 0 to 6), H q Cl 6-q Si2O (q = 0 to 4), (CH3) u H v SiCl 4-u-v (u = 1 to 4 and v = 0 or 1) and may further contain one or more components selected from the group consisting of CH4, C2H6, CO, CO2, O2, N2. These components may be derived from, for example, the hydrogen recovered in the integrated system.

[0053] The reaction gas may further contain a carrier gas that does not contribute to the reaction, such as a noble gas like nitrogen gas or argon.

[0054] The composition of the reaction gas is typically measured prior to supply to the reactor by Raman and infrared spectroscopy and gas chromatography. This can be done either via an extraction test and subsequent "off-line analysis" mode through a sample, or otherwise via "on-line" analytical equipment connected to the system.

[0055] It is preferred that the ratio of the fluidized bed height to the reactor diameter in the fluidized bed reactor is from 10:1 to 1:1, preferably from 8:1 to 2:1, and particularly preferably from 6:1 to 3:1. The fluidized bed height is the thickness or size of the fluidized bed.

[0056] The chlorosilanes selected from General Formulas 1 and 2, and the chlorosilanes produced by the process according to the present invention are preferably at least one chlorosilane selected from the group consisting of monochlorosilane, dichlorosilane, TCS, Si2Cl6 and HSi2Cl5. In the case of the chlorosilane of General Formula 1, TCS is particularly preferred.

[0057] Further by-products that can be produced include halosilanes such as monochlorosilane (H3SiCl), dichlorosilane (H2SiCl2), silicon tetrachloride (STC, SiCl4) and di- and oligosilanes. Impurities such as hydrocarbons, organochlorosilanes and metal chlorides can also be by-products. Therefore, typically, distillation of the crude product is then carried out to produce high-purity chlorosilanes selected from General Formulas 1 and 2.

[0058] The process according to the present invention is preferably introduced into an integrated system for producing polycrystalline silicon. The integrated system particularly includes the following processes: - Production of TCS according to the described process. - Purification of the produced TCS to obtain semiconductor-grade TCS. - Deposition of polycrystalline silicon, preferably according to the Siemens process or as granules. - Further processing of the obtained polycrystalline silicon. Reuse of ultra-high purity silicon dust generated during the production / further processing of polycrystalline silicon.

[0059] FIG. 1 shows, by way of example, a fluidized bed reactor 1 for carrying out a process according to the invention. The reaction gas 2 is preferably blown onto the contact mass from below and optionally laterally (e.g., in the tangential or orthogonal direction to the downward gas flow), thereby fluidizing the particles of the contact mass to form a fluidized bed 3. To initiate the reaction, the fluidized bed 3 is generally heated using a heating device (not shown) disposed outside the reactor. Heating typically does not require continuous operation. A portion of the particles is carried by the gas stream from the fluidized bed 3 into the void 4 above the fluidized bed 3. The void 4 is characterized by a very low solid density that decreases in the direction of the reactor outlet 5.

Example

[0060] All examples used the same type of silicon in terms of purity, quality, second element content, and impurities. The particle fraction used in the operating granulate was produced by crushing lump Si mg (98.9% by mass Si) and then pulverizing it or by performing spraying techniques known to those skilled in the art to produce fine particle Si mg (98.9% by mass Si). The fraction was optionally classified by sieving / screening. Thus, a particle fraction having a constant value for the structural parameter S was produced in a targeted manner. Then, a contact mass having a predetermined mass fraction of silicon-containing particles having a structural parameter S of 0 or more was mixed by combining and mixing these particle fractions. The remainder of the particle fraction contained silicon-containing particles having a structural parameter S less than 0. The sum of the particle fractions was 100% by mass. The granulate used in this experiment had a particle size parameter d 50 between 330 and 350 μm. No further catalyst or promoter was added to ensure the maximum possible comparability between individual experiments.

[0061] The following process was used in all examples. During the experiment, the operating temperature of the fluidized bed reactor was about 320 °C. This temperature was maintained approximately constant over the entire experimental period using cooling means such that the height of the fluidized bed remained substantially constant over the entire experimental period and a constant molar concentration ratio of 3:1 of reactants (HCl:Si) was established. Both HCl and the granular material for operation were added in such a way that. The reactor was operated at a positive pressure of 0.1 MPa over the entire experimental period. Both liquid samples and gas samples were taken at runtimes of 48 hours and 49 hours, respectively. Before the measurement of the TCS selectivity and the proportion [wt%] of the high melting point solvent therefrom, the condensable proportion of the product gas stream (chlorosilane gas stream) was concentrated at -40 °C using a cold trap and analyzed by gas chromatography (GC). Detection was via a thermal conductivity detector. The non-condensable content of the product gas stream was analyzed for unreacted HCl [vol%] using infrared spectroscopy. The values obtained after 48 hours and 49 hours were averaged in each case. After each run, the reactor was emptied completely and refilled with the contact mass.

[0062] The contact masses used and the results of the experiments are summarized in Table 1. ms is the mass fraction of particles S having a structural parameter S greater than 0.

[0063]

Table 1

Claims

1. General formulas 1 and 2: H ｎ SiCl ４－ｎ (1), H ｍ Cl ６－ｍ Si ２ (2), Herein, n is from 0 to 3, and m is from 0 to 4 A method for producing a chlorosilane selected therefrom in a fluidized bed reactor, wherein a hydrogen chloride-containing reaction gas reacts with an operating granular material containing silicon at a temperature of 280 °C to 400 °C, wherein the operating granular material, which is understood to mean the granular material or granular mixture for operation introduced into the fluidized bed reactor, contains silicon-containing particles s represented by a structural parameter S of at least 1% by mass, where S has a value of 0 or more and is calculated as follows: 【Number 1】 Herein, φ Ｓ is the symmetric weighted sphericity factor that is the product of the symmetry factor and the sphericity. The symmetry factor is calculated from the minimum ratio of the ratios of the paths from end to end passing through the center of gravity of the particle in each measurement direction, the sphericity represents the ratio between the surface area and the square of the circumference of the particle image, the symmetric weighted sphericity factor φS of the particles s is from 0.70 to 1, ρ ＳＤ is the packing density [g / cm ３ of the particulate fraction of the granulated product for use, the packing density ρSD of the particle fraction of the operating granular material having a structural parameter S of 0 or more is from 0.8 to 2.0 g / cm3, measured in accordance with DIN ISO 697, ρ Ｆ is the average particle solid density [g / cm ３ , and the average particle solid density ρF of the particles s of the particle fraction having a structural parameter S of 0 or more is from 2.20 to 2.70 g / cm3, measured in accordance with DIN 66137-2:2019-03, a method.

2. The granular material for use in the operation has a particle size parameter d of 70 to 1000 μm ５０ The production method according to claim 1, wherein the particle size parameter is measured in accordance with DIN ISO 9276-2

3. Before introduction into the reactor, the reaction gas contains at least 50% by volume of hydrogen chloride, the production method according to claim 1 or 2.

4. HCl and silicon are present in an HCl / Si molar ratio of 5:1 to 2.5:1, the production method according to any one of claims 1 to 3.

5. The produced chlorosilane of general formula 1 is trichlorosilane (TCS), the production method according to any one of claims 1 to 4.

Images