Tetrachlorosilane hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention provides a tetrachlorosilane hydrogenation catalyst and a preparation method and application thereof, the tetrachlorosilane hydrogenation catalyst comprises a porous carrier and active particles loaded on the porous carrier, and the active particles comprise copper, nickel and cobalt; the particle size of the active particles is not higher than 300nm, and the mass percentage content of the active particles in the tetrachlorosilane hydrogenation catalyst is not lower than 20wt%; meanwhile, in the hydrogenation reaction process containing the tetrachlorosilane hydrogenation catalyst, the change rate of the conversion rate of tetrachlorosilane is not higher than 14% / 24 h. The tetrachlorosilane hydrogenation catalyst has high stability in the reaction process, the problem that the conversion rate of tetrachlorosilane is seriously reduced can be remarkably improved, and the production cost of polycrystalline silicon is reduced.

Description

Technical Field

[0001] The invention belongs to the field of catalysts and relates to a tetrachlorosilane hydrogenation catalyst, in particular to a tetrachlorosilane hydrogenation catalyst and a preparation method and application thereof. Background Art

[0002] In recent years, with the increasing demand in the field of new energy, the global polysilicon production capacity has entered a period of rapid growth. The modified Siemens method is usually used for production, that is, polysilicon is prepared by trichlorosilane chemical vapor deposition. The products include polysilicon, tetrachlorosilane and hydrogen chloride. Among them, tetrachlorosilane can be converted by thermal hydrogenation or cold hydrogenation process to obtain trichlorosilane, the raw material for polysilicon production, which can be returned to the production system for reuse.

[0003] Generally, the thermal hydrogenation process is to react tetrachlorosilane and hydrogen at a high temperature of 1200-1250°C, but the conversion rate of tetrachlorosilane is only 15-20%; the cold hydrogenation process is to introduce a catalyst, add tetrachlorosilane, hydrogen, silicon powder and catalyst into a fluidized bed or fixed bed for reaction, and reduce the reaction temperature to 400-600°C and the pressure to 2-4MPa, which can achieve higher reaction efficiency, greatly reduce the heat required for the reaction, and reduce energy consumption. The core of tetrachlorosilane cold hydrogenation technology is the catalyst. The activity of the catalyst has a significant impact on the conversion rate of tetrachlorosilane. Therefore, it is crucial to optimize the performance of the catalyst.

[0004] However, existing catalysts may have problems such as loss of active components and catalyst pulverization during the catalytic reaction. Therefore, as the reaction proceeds, the conversion rate of tetrachlorosilane drops severely, and fresh catalysts must be frequently added, resulting in high costs for polysilicon. Summary of the invention

[0005] In view of the above-mentioned defects, the present invention provides a tetrachlorosilane hydrogenation catalyst. In the hydrogenation reaction including the catalyst, the tetrachlorosilane conversion rate is high, and the change rate of the tetrachlorosilane conversion rate is not higher than 14% / 24h, which can significantly improve the problem of severe decrease in tetrachlorosilane conversion rate and reduce the production cost of polysilicon.

[0006] The invention provides a method for preparing a tetrachlorosilane hydrogenation catalyst. The catalyst prepared by the preparation method can improve the conversion rate of tetrachlorosilane and effectively improve the stability of the conversion rate of tetrachlorosilane during the reaction process, thereby improving the problem of severe decrease in the conversion rate of tetrachlorosilane and reducing the production cost of polysilicon.

[0007] The invention provides a method for preparing trichlorosilane. Since the tetrachlorosilane hydrogenation catalyst or the tetrachlorosilane hydrogenation catalyst prepared by the preparation method is used in the reaction of preparing trichlorosilane by hydrogenating tetrachlorosilane, the conversion rate of tetrachlorosilane in the reaction is high and the conversion rate of tetrachlorosilane has high stability, thereby improving the problem of severe decrease in the conversion rate of tetrachlorosilane.

[0008] The present invention provides a tetrachlorosilane hydrogenation catalyst, which comprises a porous carrier and active particles loaded on the porous carrier, wherein the active particles comprise copper, nickel and cobalt;

[0009] The particle size of the active particles is not higher than 300 nm, and the mass percentage of the active particles in the tetrachlorosilane hydrogenation catalyst is not lower than 20 wt %;

[0010] During the hydrogenation reaction process including the tetrachlorosilane hydrogenation catalyst, the change rate of tetrachlorosilane conversion is no higher than 14% / 24h.

[0011] Furthermore, the porous carrier of the tetrachlorosilane hydrogenation catalyst comprises a porous core and a porous silica shell layer located on at least a portion of the surface of the porous core; the porous core and the porous silica shell layer both comprise interconnecting holes connected to the outside, and the active particles are located in the interconnecting holes;

[0012] The number of the interconnecting pores is 10% to 50% of the number of pores in the porous carrier.

[0013] Furthermore, the thickness of the porous silica shell layer is 1 nm-180 nm.

[0014] Furthermore, the active particles also include at least one of selenium, molybdenum, iron, chromium, zinc and zirconium.

[0015] The present invention provides a method for preparing a tetrachlorosilane hydrogenation catalyst, comprising the following steps:

[0016] (1) mixing raw materials including a soluble nickel salt, a soluble copper salt, a soluble cobalt salt, and a porous material with deionized water to obtain a mixed solution; in the mixed solution, the mass percentage of copper is 0.01wt%-10wt%, the mass percentage of cobalt is 0.001wt%-2wt%, and the mass percentage of nickel is 0.001wt%-2wt%;

[0017] (2) adding a precipitant solution to the mixed solution to perform a precipitation reaction, and maintaining the pH of the reaction system at 8-12. When the pH value is stable, aging is performed at a temperature of 40° C. to 80° C. for 1 h to 15 h. After aging, solid-liquid separation is performed, and the obtained solid phase is washed with water until it is neutral and dried to obtain a first product.

[0018] (3) After the first product is reduced, a mixture of water vapor and nitrogen is introduced for a first purge; in the first purge, the temperature is 100° C.-200° C., the time is 5 min-30 min, the molar ratio of water vapor to nitrogen is 1:(1-10), the pressure is 0.1 MPa-0.4 MPa, and the volume space velocity of the water vapor and nitrogen is ≥10 h -1 ;

[0019] (4) introducing a mixture of tetrachlorosilane and nitrogen into the system after the first purge for a second purge; in the second purge, the temperature is 60° C.-80° C., the time is 5 min-30 min, the molar ratio of tetrachlorosilane to nitrogen is 1:(0.1-50), the pressure is 0.1 MPa-0.4 MPa, and the volume space velocity of the tetrachlorosilane gas and the nitrogen is ≥100 h / min respectively. -1 ;

[0020] (5) In a nitrogen atmosphere, the system after the second purge is subjected to a heating and calcining treatment to obtain a second product; wherein the heating rate is 1°C / min-30°C / min, the calcining temperature is 200°C-500°C, the calcining time is 1h-10h, the pressure is 0.1Mpa-0.4Mpa, and the volume space velocity of nitrogen is ≥100h -1 ;

[0021] (6) etching the second product with an aqueous solution of sodium hydroxide and / or potassium hydroxide to obtain a third product, wherein the mass concentration of the second product in the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.2 g / mL-1 g / mL; the molar concentration of the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.5 mol / L-6 mol / L, the etching temperature is 20° C.-80° C., and the etching treatment time is 0.5 h-24 h;

[0022] (7) The third product is washed with water until it is neutral, dried, reduced, and calcined. The calcination temperature is 300° C.-800° C. and the calcination time is 4 h-8 h to obtain the tetrachlorosilane hydrogenation catalyst.

[0023] Furthermore, in step (2), the precipitant solution is added at a rate of 0.5 mL / min-5 mL / min.

[0024] Furthermore, in step (3), the reduction treatment includes: purging with an inert gas for 0.5 h to 2 h for replacement, and then activating the first product with an activation atmosphere at an activation temperature of 200° C. to 400° C. and a pressure of 0.1 MPa to 0.4 MPa for 1 h to 5 h;

[0025] The activation atmosphere is a reducing gas, or a mixed gas of a reducing gas and an inert gas in a molar ratio of (0.5-2):1.

[0026] Furthermore, in step (7), the drying temperature is 100°C-120°C, and the drying time is 4h-12h.

[0027] The present invention provides a method for preparing trichlorosilane. The tetrachlorosilane hydrogenation catalyst described in any one of the above items or the tetrachlorosilane hydrogenation catalyst prepared by any one of the above methods is used in the reaction of hydrogenating tetrachlorosilane to prepare trichlorosilane, so as to prepare trichlorosilane.

[0028] Furthermore, the method further comprises recovering and regenerating the tetrachlorosilane hydrogenation catalyst after the reaction, wherein the recovery and regeneration process comprises:

[0029] Using an aqueous solution of sodium hydroxide and / or potassium hydroxide to etch, wash, dry and reduce the tetrachlorosilane hydrogenation catalyst after the reaction to obtain a recovered tetrachlorosilane hydrogenation catalyst;

[0030] The molar concentration of the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.5 mol / L-6 mol / L, the etching temperature is 20° C.-80° C., and the etching treatment time is 0.5 h-24 h.

[0031] The tetrachlorosilane hydrogenation catalyst of the present invention comprises a porous carrier and active particles loaded on the porous carrier, wherein the particle size of the active particles is not higher than 300 nm, and the mass percentage of the active particles in the catalyst is not lower than 20 wt %, so that in the hydrogenation reaction process including the catalyst, the change rate of the tetrachlorosilane conversion rate is not higher than 14% / 24h, the stability of the tetrachlorosilane conversion rate in the reaction process is effectively improved, the problem of severe decrease in the tetrachlorosilane conversion rate in the reaction process is improved, and the production cost of polysilicon is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the preparation process of the tetrachlorosilane hydrogenation catalyst in the present invention;

[0033] Figure 2 This is a SEM image of the catalyst in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The first aspect of the present invention provides a tetrachlorosilane hydrogenation catalyst, the tetrachlorosilane hydrogenation catalyst comprises a porous carrier and active particles supported on the porous carrier, the active particles comprising copper, nickel, and cobalt;

[0036] The particle size of the active particles is not higher than 300 nm, and the mass percentage of the active particles in the tetrachlorosilane hydrogenation catalyst is not lower than 20 wt %;

[0037] During the hydrogenation reaction including the tetrachlorosilane hydrogenation catalyst, the change rate of tetrachlorosilane conversion is no higher than 14% / 24h.

[0038] It can be understood that there are a certain number of pores in the porous carrier of the present invention, which has a certain specific surface area, and the active particles are loaded on the porous carrier.

[0039] The particle size of the active particles in the present invention can be measured by scanning electron microscopy (SEM). Specifically, the catalyst is subjected to SEM testing, and the SEM image in any 5μm*5μm area is selected to measure the particle size of the active particles in the area. The average value is used to obtain the particle size of the active particles in the present invention.

[0040] The mass percentage of the active particles in the tetrachlorosilane hydrogenation catalyst of the present invention can be measured by ICP-OES.

[0041] The present invention does not impose any specific limitation on the specific surface area and particle size of the porous carrier, and a suitable specific surface area and particle size can be selected according to specific requirements in the actual hydrogenation reaction process.

[0042] The rate of change of tetrachlorosilane conversion in the present invention is calculated by the following steps:

[0043] The catalyst and silicon powder are uniformly mixed, and the mass ratio of the catalyst to the silicon powder is 10:1; the mixture of the catalyst and the silicon powder is loaded into the reactor, and the ratio of the catalyst layer height to the diameter of the reactor should be appropriate to ensure that the gas passes through the catalyst bed uniformly; the reactor is purged with nitrogen to exclude air; the temperature of the reactor is raised to the set temperature of 450°C, silicon tetrachloride is injected into the reactor through a metering pump, and mixed with hydrogen, and the feed amount of silicon tetrachloride and hydrogen is adjusted to make the hydrogen-silicon ratio (molar ratio) 4:1; the reactor pressure is set to 3.0MPa, and the reaction temperature is set to 1000℃. The temperature is 450° C., and the reaction products at the outlet of the reactor are monitored in real time by an online chromatograph to obtain a gas chromatogram; then the conversion rate of silicon tetrachloride (%) = (peak area of ​​dichlorosilane + peak area of ​​trichlorosilane) / (peak area of ​​dichlorosilane + peak area of ​​trichlorosilane + peak area of ​​tetrachlorosilane) × 100%; the change rate of tetrachlorosilane conversion (% / 24h) = (tetrachlorosilane conversion rate when the reaction reaches X hours - tetrachlorosilane conversion rate when the reaction reaches (X+24) hours) / tetrachlorosilane conversion rate when the reaction reaches X hours.

[0044] The tetrachlorosilane hydrogenation catalyst of the present invention can improve the tetrachlorosilane conversion rate in the hydrogenation reaction, and can improve the stability of the tetrachlorosilane conversion rate, and improve the problem of severe decline in the tetrachlorosilane conversion rate. Based on this phenomenon, the inventor analyzes the tetrachlorosilane hydrogenation catalyst and believes that it may be: when the tetrachlorosilane hydrogenation catalyst includes a porous carrier and active particles loaded on the porous carrier, the active particles include copper, nickel, and cobalt, and the particle size of the active particles is not higher than 300nm, and the mass percentage of the active particles in the tetrachlorosilane hydrogenation catalyst is not less than 20wt%, the particle size of the active particles is small, the loading amount on the porous carrier is high, and the active particles are evenly distributed on the porous carrier, so that more active centers can be provided during the hydrogenation reaction, thereby improving the catalytic efficiency, so that a higher tetrachlorosilane conversion rate is obtained; at the same time, the stability of the tetrachlorosilane conversion rate is improved, so that the change rate of the tetrachlorosilane conversion rate is not higher than 14% / 24h, thereby effectively improving the problem of severe decline in the tetrachlorosilane conversion rate and reducing production costs.

[0045] In a specific embodiment, the porous support of the tetrachlorosilane hydrogenation catalyst comprises a porous core and a porous silica shell layer located on at least a portion of the surface of the porous core; the porous core and the porous silica shell layer both comprise interconnected pores connected to the outside, and the active particles are located in the interconnected pores;

[0046] The number of interconnected holes is 10%-50% of the number of holes in the porous carrier. At this time, the active particles in the interconnected holes are embedded in the porous shell of silica and contact the outside. During the reaction, they can participate in the catalytic reaction as active centers. This special structure can improve the binding force between the active particles and the porous carrier, making it difficult for the active particles to fall off during the reaction, thereby further improving the stability of the catalytic performance; when the number of interconnected holes is 10%-50% of the number of holes in the porous carrier, it can ensure that the catalyst has enough active centers, thereby further improving the conversion rate of tetrachlorosilane.

[0047] In a specific embodiment, the thickness of the porous silica shell is 1 nm-180 nm. Within this range, not only can the binding force between the active particles and the porous carrier be further improved, the strength of the tetrachlorosilane hydrogenation catalyst be improved, and the catalyst pulverization problem caused by collision and wear during the reaction be improved; it can also ensure that there are enough active centers in the catalyst to participate in the catalytic reaction, thereby further improving the stability of the tetrachlorosilane conversion rate and increasing the service life of the catalyst.

[0048] Specifically, the thickness of the generated silicic acid precipitate can be controlled by controlling the temperature, treatment time, molar ratio of water vapor and nitrogen, volumetric space velocity and pressure in the first purge process, and the temperature, treatment time, molar ratio of tetrachlorosilane and nitrogen, volumetric space velocity and pressure in the second purge process during the preparation process, so as to further control the thickness of the porous silica shell layer; the etching degree can also be controlled by controlling the molar concentration of the sodium hydroxide and / or potassium hydroxide aqueous solution, the etching temperature and the etching time during the etching process, so as to further control the thickness of the porous silica shell layer, so that the thickness of the porous silica shell layer is between 1nm and 180nm.

[0049] The thickness of the porous silica shell layer in the present invention can be measured by a transmission electron microscope (TEM).

[0050] In a specific embodiment, the active particles further include at least one of selenium, molybdenum, iron, chromium, zinc, and zirconium. When the active particles also include the aforementioned metal particles, it is beneficial to the dehydrogenation reaction, and can also cooperate with copper, nickel, and cobalt to improve the dispersion uniformity of the active particles.

[0051] The second aspect of the present invention provides a method for preparing the tetrachlorosilane hydrogenation catalyst of the first aspect, comprising the following steps:

[0052] (1) mixing raw materials including a soluble nickel salt, a soluble copper salt, a soluble cobalt salt, and a porous material with deionized water to obtain a mixed solution; in the mixed solution, the mass percentage of copper is 0.01wt%-10wt%, the mass percentage of cobalt is 0.001wt%-2wt%, and the mass percentage of nickel is 0.001wt%-2wt%;

[0053] (2) adding a precipitant solution to the mixed solution to perform a precipitation reaction, and maintaining the pH of the reaction system at 8-12. When the pH value is stable, aging is performed at a temperature of 40° C. to 80° C. for 1 h to 15 h. After aging, solid-liquid separation is performed, and the obtained solid phase is washed with water until it is neutral and dried to obtain a first product.

[0054] (3) After the first product is reduced, a mixture of water vapor and nitrogen is introduced for a first purge; in the first purge, the temperature is 100°C-200°C, the time is 5min-30min, the molar ratio of water vapor to nitrogen is 1:(1-10), the pressure is 0.1Mpa-0.4Mpa, and the volume space velocity of water vapor and nitrogen is ≥10h-1. -1 ;

[0055] (4) introducing a mixture of tetrachlorosilane and nitrogen into the system after the first purge for a second purge; in the second purge, the temperature is 60° C.-80° C., the time is 5 min-30 min, the molar ratio of tetrachlorosilane to nitrogen is 1:(0.1-50), the pressure is 0.1 MPa-0.4 MPa, and the volume space velocity of tetrachlorosilane gas and nitrogen is ≥100 h -1 ;

[0056] (5) In a nitrogen atmosphere, the system after the second purge is subjected to a heating and calcining treatment to obtain a second product; wherein the heating rate is 1°C / min-30°C / min, the calcining temperature is 200°C-500°C, the calcining time is 1h-10h, the pressure is 0.1Mpa-0.4Mpa, and the volume space velocity of nitrogen is ≥100h -1 ;

[0057] (6) etching the second product with an aqueous solution of sodium hydroxide and / or potassium hydroxide to obtain a third product, wherein the mass concentration of the second product in the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.2 g / mL-1 g / mL; the molar concentration of the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.5 mol / L-6 mol / L, the etching temperature is 20° C.-80° C., and the etching treatment time is 0.5 h-24 h;

[0058] (7) The third product is washed with water until it is neutral, dried, reduced, and calcined at a temperature of 300° C. to 800° C. for a time of 4 h to 8 h to obtain a tetrachlorosilane hydrogenation catalyst.

[0059] Figure 1 This is a schematic diagram of the preparation process of tetrachlorosilane hydrogenation catalyst.

[0060] Specifically, in step (1), raw materials including soluble nickel salt, soluble copper salt, soluble cobalt salt and porous material are uniformly mixed with deionized water to be fully dissolved in the deionized water, and the porous material is added and fully mixed to obtain a mixed solution; in the mixed solution, the mass percentage of copper is 0.01wt%-10wt%, the mass percentage of cobalt is 0.001wt%-2wt%, and the mass percentage of nickel is 0.001wt%-2wt%.

[0061] Since the mass percentage of metal ions in the mixed solution will affect the particle size of the precipitated particles generated in the subsequent precipitation process, when the mass percentages of copper, cobalt and nickel in the mixed solution are respectively within the above ranges, it is more conducive to the formation of small precipitated particles, thereby reducing the particle size of active particles in the catalyst, and at the same time, it can also improve the problems of impurity adsorption and uneven precipitation.

[0062] Furthermore, heating may be performed during the mixing process to promote the dissolution of the soluble nickel salt, the soluble copper salt and the soluble cobalt salt so that they are fully dissolved in the deionized water.

[0063] The porous material in the present invention is a porous material that is insoluble in an alkaline solution having a pH value of not less than 10.

[0064] The present invention does not specifically limit the types of soluble nickel salts, soluble copper salts, and soluble cobalt salts. For example, soluble copper salts include at least one of copper sulfate, copper nitrate, copper chloride, and copper acetate; soluble nickel salts include at least one of nickel sulfate, nickel nitrate, nickel chloride, and nickel acetate; soluble cobalt salts include at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride. When the aforementioned compounds are mixtures of multiple specific compounds, the present invention does not make too many restrictions on the ratios between the specific compounds.

[0065] The present invention does not specifically limit the type of porous material, for example, it includes at least one of silicon dioxide, porous carbon, silicon carbide, zeolite, magnesium oxide, zirconium oxide, and titanium dioxide. When the aforementioned porous carrier is a mixture of multiple specific substances, the present invention does not make too many restrictions on the ratio between the specific substances.

[0066] The present invention does not specifically limit the sources of the soluble nickel salt, the soluble copper salt, the soluble cobalt salt and the porous material, and any commercially available product or a product prepared by a conventional preparation method known to those skilled in the art may be used.

[0067] The present invention does not specifically limit the mixing method. It is only necessary to fully dissolve the soluble nickel salt, the soluble copper salt, and the soluble cobalt salt in deionized water, and to fully diffuse the mixed solution into the internal pores of the porous carrier. For example, mixing can be performed by stirring and / or ultrasound. The mixing time is preferably 1-5 hours, and more preferably 2-3 hours.

[0068] In step (2), a precipitant solution is added to the mixed solution, and the pH value of the reaction system is adjusted to 8-12. During the addition process, when the pH value stabilizes, the precipitation reaction ends; static aging is performed, the aging temperature is 40°C-80°C, and the aging time is 1h-15h; after the aging, solid-liquid separation is performed, and the obtained solid phase is washed with water to neutrality and dried to obtain a first product, which includes a porous material and precipitated particles deposited on the surface of the porous material and inside the pores.

[0069] In this process, the precipitant reacts with the soluble metal salt in the mixed solution. When the pH is 8-12, the particle size of the metal precipitate particles can be reduced, so that the metal precipitate particles can be evenly deposited on the surface and inside the pores of the porous material. After the precipitation reaction is completed, aging is carried out. During the aging process, the metal precipitate particles will dissolve and re-deposit. When the aging temperature is 40℃-80℃ and the aging time is 1h-15h, more uniform particles can be formed and the impurity content can be further reduced.

[0070] Furthermore, the pH value of the reaction system is 9-10.

[0071] Furthermore, the aging temperature is 60°C-70°C, and the aging time is 3h-5h.

[0072] Furthermore, the mass percentage of the precipitant in the precipitant solution is 10wt%-20wt%. Within this range, it is more conducive to forming metal precipitates with smaller particles, thereby further reducing the particle size of the active particles.

[0073] The present invention does not limit the type of the precipitant in the precipitant solution, for example, it includes at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium hydroxide, ammonium carbonate, ammonium bicarbonate, urea and ammonia water.

[0074] The present invention does not specifically limit the method of solid-liquid separation. For example, separation can be performed by filtration and / or centrifugation.

[0075] The method of water washing in the present invention is not specifically limited, and it is sufficient that the solid phase after water washing is neutral.

[0076] The present invention does not specifically limit the drying temperature and drying time. It is only necessary to evaporate the water in the solid phase after washing. For example, the drying temperature is 80°C-120°C, and the drying time is 4h-12h. Furthermore, the drying temperature is 100°C-120°C, and the drying time is 6h-8h.

[0077] In step (3), the first product is subjected to a reduction treatment to reduce the metal precipitate particles to metal active particles, and the metal active particles are supported on the surface and pores of the porous material by adhesion. After the reduction treatment is completed, a mixed gas of water vapor and nitrogen is introduced for a first purge to uniformly distribute the water vapor on the surface and pores of the first product. In the first purge, the temperature is 100° C.-200° C., the time is 5 min-30 min, the molar ratio of water vapor to nitrogen is 1:(1-10), the pressure is 0.1 Mpa-0.4 Mpa, and the volume space velocity of water vapor and nitrogen is ≥10 h-10, respectively. -1 .

[0078] In step (4), a mixture of tetrachlorosilane and nitrogen is introduced into the system after the first purge for a second purge. In the second purge, the temperature is 60°C-80°C, the time is 5min-30min, the molar ratio of tetrachlorosilane to nitrogen is 1:(0.1-50), the pressure is 0.1Mpa-0.4Mpa, and the volume space velocity of tetrachlorosilane gas and nitrogen is ≥100h-1. -1 During the second purge process, tetrachlorosilane is hydrolyzed to generate silicate precipitate, which is coated on at least part of the surface of the porous material and at least part of the surface of the metal active particles. At this time, the metal active particles are embedded in the silicate precipitate layer.

[0079] In step (5), nitrogen is introduced into the system after the second purge, and the temperature is increased to 200°C-500°C at a heating rate of 1°C / min-30°C / min, the holding time is 1h-10h, the pressure is 0.1Mpa-0.4Mpa, and the volume space velocity of nitrogen is ≥100h -1 In this process, the silicic acid precipitate coated on at least part of the surface of the porous material and at least part of the surface of the metal active particles is dehydrated to form a silicon dioxide shell layer.

[0080] In step (6), the second product is placed in an aqueous solution of sodium hydroxide and / or potassium hydroxide with a molar concentration of 0.5mol / L-6mol / L for etching, the mass concentration of the second product in the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.2g / mL-1g / mL, the etching temperature is 20°C-80°C, and the etching time is 0.5h-24h to obtain a third product. The etching treatment can expose at least part of the metal active particles in the silica shell to participate in the catalytic reaction; when the molar concentration of the aqueous solution of sodium hydroxide and / or potassium hydroxide, the mass concentration of the second product in the aqueous solution of sodium hydroxide and / or potassium hydroxide, the etching temperature and the etching time are within the aforementioned range, it can be ensured that the metal active particles will not fall off due to excessive etching, and it can also avoid insufficient exposure of active components due to insufficient etching, resulting in a decrease in catalyst reaction performance.

[0081] Furthermore, stirring may be performed during the etching process to ensure uniformity of etching. Preferably, the stirring speed is 500 r / min-1000 r / min.

[0082] In step (7), the third product is washed with water until neutral, dried, reduced, and then calcined at 300° C.-800° C. for 4 h-8 h to obtain a tetrachlorosilane hydrogenation catalyst.

[0083] It should be noted that the reduction conditions in step (7) are consistent with the above-mentioned reduction treatment.

[0084] The preparation method of the tetrachlorosilane hydrogenation catalyst of the present invention comprises the following steps: firstly, metal active particles are loaded on the surface of a porous material and inside the pores, and then a layer of silicon dioxide shell is coated on at least part of the surface of the porous material and at least part of the surface of the metal active particles, and a hole expansion treatment is performed by etching to expose at least part of the metal active particles in the silicon dioxide shell. At this time, the metal active particles are embedded in the silicon dioxide shell, which can improve the binding force between the metal active particles and the porous carrier, so that the active particles of the prepared catalyst are not easy to fall off during the reaction process, and then the change rate of the tetrachlorosilane conversion rate is not higher than 14% / 24h, thereby improving the stability of the catalytic performance. At the same time, by controlling the parameters in the preparation process, the particle size of the active particles is not higher than 300nm, and the mass percentage of the active particles in the tetrachlorosilane hydrogenation catalyst is not less than 20wt%, thereby effectively improving the catalytic performance of the catalyst and improving the conversion rate of tetrachlorosilane in the hydrogenation reaction.

[0085] In a specific embodiment, in step (2), the precipitant solution is added at a rate of 0.5 mL / min-5 mL / min. When the precipitant solution is added, it is slowly added at a rate of 0.5 mL / min-5 mL / min, which is conducive to the formation of small-sized metal precipitate particles and can further reduce the particle size of active particles, thereby making the catalyst have higher catalytic activity and improving the conversion rate of tetrachlorosilane.

[0086] In a specific embodiment, in step (3), the reduction treatment comprises: purging with an inert gas for 0.5 h to 2 h for replacement, and then activating the first product with an activation atmosphere at an activation temperature of 200° C. to 400° C. and a pressure of 0.1 MPa to 0.4 MPa for 1 h to 5 h;

[0087] The activation atmosphere is a reducing gas, or a mixture of a reducing gas and an inert gas at a molar ratio of (0.5-2): 1. When the reduction treatment is performed through the above steps, the metal precipitate particles can be fully reduced, avoiding the problem of loss of active components due to incomplete reduction, thereby improving the catalyst activity and improving the conversion rate and conversion rate stability of tetrachlorosilane.

[0088] The present invention does not impose any specific limitation on the equipment for carrying out the reduction treatment, and the reduction treatment can be carried out in any equipment capable of introducing an activation atmosphere and heating, such as a tubular furnace and / or a fixed bed reactor.

[0089] In a specific embodiment, in step (7), the drying temperature is 100° C.-120° C., and the drying time is 4 h-12 h. Within this range, the third product can form a better crystal structure, improve the reaction activity of the catalyst, and further improve the conversion rate and conversion rate stability of tetrachlorosilane.

[0090] In a specific embodiment, in step (1), the mixed solution further includes at least one of a soluble selenium salt, a soluble molybdenum salt, a soluble iron salt, a soluble chromium salt, a soluble zinc salt, and a soluble zirconium salt. When the mixed solution further includes the aforementioned compounds, the dispersion of copper, nickel, and cobalt in the porous material can be promoted.

[0091] The third aspect of the present invention provides a method for preparing trichlorosilane, wherein the tetrachlorosilane hydrogenation catalyst of the first aspect or the tetrachlorosilane hydrogenation catalyst prepared by the preparation method of the second aspect is used in the reaction of preparing trichlorosilane by hydrogenation of tetrachlorosilane to prepare trichlorosilane. In the reaction process, the conversion rate of tetrachlorosilane and the yield of trichlorosilane are high, and the change in the conversion rate of tetrachlorosilane is low.

[0092] In a specific embodiment, the tetrachlorosilane hydrogenation catalyst after the reaction is further recovered and regenerated, and the recovery and regeneration process includes:

[0093] Using an aqueous solution of sodium hydroxide and / or potassium hydroxide to etch, wash, dry and reduce the tetrachlorosilane hydrogenation catalyst after the reaction to obtain a recovered tetrachlorosilane hydrogenation catalyst;

[0094] The molar concentration of the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.5 mol / L-6 mol / L, the etching temperature is 20°C-80°C, and the etching treatment time is 0.5h-24h. Through recycling and regeneration, the tetrachlorosilane hydrogenation catalyst after the reaction is etched again to expose the unexposed metal active particles in the silicon dioxide shell layer, thereby improving the reaction activity of the tetrachlorosilane hydrogenation catalyst, achieving recycling and extending the service life of the catalyst.

[0095] Hereinafter, the tetrachlorosilane hydrogenation catalyst of the present invention is described in detail through specific examples.

[0096] Example 1

[0097] (1) 7 g of copper chloride (chemical formula CuCl 2 ·2H 2 O), 1g nickel chloride (chemical formula NiCl 2 6H 2 O), 1g cobalt chloride (chemical formula CoCl 2 6H 2 O) add 60 mL of deionized water, keep the temperature at 80° C. in an oil bath, and mix ultrasonically for 30 min to fully dissolve the solute; add 10 g of silicon dioxide, stir with a magnetic stirrer at 80° C. and 1000 r / min for 2 h to fully mix, to obtain a mixed solution;

[0098] (2) adjusting the pH of the mixed solution to 10 using a 15 wt % sodium carbonate solution and maintaining the pH at 10, and after the pH value stabilizes, aging at 60° C. for 3 h; filtering the reaction system, and washing the separated solid phase with deionized water until it is neutral, and then drying at 120° C. for 6 h to obtain a first product;

[0099] (3) The first product was placed in a fixed bed reaction tube, and nitrogen was introduced at 0.1 MPa for 1 hour at a flow rate of 50 mL / min for replacement; then a mixture of hydrogen and nitrogen was introduced at a flow rate of 50 mL / min, the activation temperature was set to 300°C, and the reduction was performed for 2 hours; after the reduction treatment was completed, a mixture of water vapor and nitrogen was introduced at 0.1 MPa for the first purge. During this process, the temperature was 120°C, the time was 5 minutes, the molar ratio of water vapor to nitrogen was 1:5, and the flow rate of nitrogen was 30 hours. -1, the flow rate of water vapor is 10h -1 ;

[0100] (4) At 0.1 MPa, a mixture of tetrachlorosilane and nitrogen was introduced into the system after the first purge for a second purge. During this process, the temperature was 70° C., the time was 20 min, the molar ratio of tetrachlorosilane to nitrogen was 1:5, and the nitrogen was 600 h -1 , Tetrachlorosilane (gas) 120h -1 ;

[0101] (5) At 0.1 MPa, nitrogen was introduced into the system after the second purge, and the flow rate of nitrogen purge gas was 300 h -1 , raising the temperature to 300°C at a heating rate of 5°C / min and keeping the temperature for 3h to obtain the second product;

[0102] (6) etching the second product with a sodium hydroxide aqueous solution, wherein the solution concentration is 0.5 mol / L, the mass concentration of the second product in the sodium hydroxide aqueous solution is 0.5 g / mL, the etching time is 30 min, and the water bath temperature is 40° C. to obtain a third product;

[0103] (7) The third product was washed with water until neutral, dried at 120° C. for 6 h, and then purged with nitrogen at 0.1 MPa for 1 h at a flow rate of 50 mL / min for replacement; then a mixture of hydrogen and nitrogen was introduced at a flow rate of 50 mL / min, the activation temperature was set at 300° C., and reduced for 2 h; finally, the reduced product was calcined in a muffle furnace at 500° C. for 6 h under a nitrogen atmosphere to obtain the tetrachlorosilane hydrogenation catalyst of this embodiment.

[0104] Example 2

[0105] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (1), copper chloride is replaced by 7 g of copper sulfate (chemical formula: CuSO 4 ), and adjusted to 72 mL with deionized water.

[0106] Example 3

[0107] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (1), copper chloride is replaced by 8 g of copper acetate (chemical formula is Cu(CO 2 CH 3 ) 2 ·H 2 O), and adjusted to 63 mL with deionized water.

[0108] Example 4

[0109] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (1), the amount of nickel chloride added is adjusted to 1.5 g.

[0110] Example 5

[0111] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (1), nickel chloride is replaced by 2 g of nickel nitrate (chemical formula: Ni(NO3)2·6H2O), and the deionized water is adjusted to 65 mL.

[0112] Example 6

[0113] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (1), the amount of cobalt chloride added is adjusted to 1.5 g.

[0114] Example 7

[0115] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (1), the amount of cobalt chloride added is adjusted to 2 g.

[0116] Example 8

[0117] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (1), silicon dioxide is replaced by 12 g of silicon carbide.

[0118] Example 9

[0119] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (1), silicon dioxide is replaced by 8 g of porous carbon.

[0120] Example 10

[0121] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (3), the introduction time of the mixed gas of water vapor and nitrogen is adjusted to 10 minutes.

[0122] Embodiment 11

[0123] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (3), the introduction time of the mixed gas of water vapor and nitrogen is adjusted to 15 minutes.

[0124] Example 12

[0125] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (4), the introduction time of the mixed gas of tetrachlorosilane and nitrogen is adjusted to 10 minutes.

[0126] Embodiment 13

[0127] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that in step (4), the introduction time of the mixed gas of tetrachlorosilane and nitrogen is adjusted to 15 minutes.

[0128] Embodiment 14

[0129] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Embodiment 1, except that in step (6), the molar concentration of the sodium hydroxide aqueous solution is adjusted to 1 mol / L.

[0130] Embodiment 15

[0131] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Embodiment 1, except that in step (6), the molar concentration of the sodium hydroxide aqueous solution is adjusted to 1.5 mol / L.

[0132] Example 16

[0133] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that step (6) and step (7) are repeated twice.

[0134] Embodiment 17

[0135] The preparation method of the tetrachlorosilane hydrogenation catalyst in this example is basically the same as that in Example 1, except that step (6) and step (7) are repeated 3 times.

[0136] Embodiment 18

[0137] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (1), 0.5 g of platinum nitrate is added to the mixed solution.

[0138] Embodiment 19

[0139] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (1), copper chloride (chemical formula CuCl 2 ·2H 2 O) was adjusted to 18 g, nickel chloride (chemical formula NiCl 2 6H 2 O) was adjusted to 7 g, cobalt chloride (chemical formula CoCl 2 6H 2O) was adjusted to 7 g, and silicon dioxide was adjusted to 35 g.

[0140] Embodiment 20

[0141] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (1), copper chloride (chemical formula CuCl 2 ·2H 2 O) is adjusted to 1g, nickel chloride (chemical formula NiCl 2 6H 2 O) was adjusted to 0.1 g, cobalt chloride (chemical formula CoCl 2 6H 2 O) was adjusted to 0.1 g, and silicon dioxide was adjusted to 1.3 g.

[0142] Embodiment 21

[0143] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (6), the concentration of the sodium hydroxide aqueous solution is adjusted to 3.5 mol / L, the etching temperature is 30° C., the etching time is 30 min, and the mass concentration of the second product in the sodium hydroxide aqueous solution is 0.6 g / mL.

[0144] Embodiment 22

[0145] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (6), the concentration of the sodium hydroxide aqueous solution is adjusted to 6 mol / L, the etching temperature is 20° C., the etching time is 30 min, and the mass concentration of the second product in the sodium hydroxide aqueous solution is 1 g / mL.

[0146] Embodiment 23

[0147] The preparation method of the tetrachlorosilane hydrogenation catalyst in this embodiment is basically the same as that in Example 1, except that in step (3), the introduction time of the mixed gas of water vapor and nitrogen is adjusted to 30 minutes, and the flow rate of nitrogen is adjusted to 90 hours. -1 , the steam flow rate is adjusted to 30h -1 ;

[0148] In step (4), the introduction time of the mixture of tetrachlorosilane and nitrogen was adjusted to 30 min, and the flow rate of nitrogen was adjusted to 900 h. -1 , the flow rate of tetrachlorosilane is adjusted to 300h -1 ;

[0149] In step (6), the etching temperature of the sodium hydroxide aqueous solution is adjusted to 20°C.

[0150] Comparative Example 1

[0151] 32-40 mesh, silicon-aluminum ratio of 60, specific surface area of ​​250-500m 2 / g of Na-ZSM-5 shaped carrier particles are immersed in a solution of barium chloride (containing 0.01wt% cobalt chloride), barium chloride (containing 0.01wt% copper chloride), and barium chloride (containing 0.01wt% nickel chloride), and immersed for 6 hours with equal volume. During the period, 100MHz ultrasonic vibration is applied from time to time. After sufficient immersion, the particles are taken out and dried at 150°C for 2 hours, and then calcined at 300-600°C for 6 hours to obtain a granular Na-ZSM-5 supported catalyst.

[0152] Comparative Example 2

[0153] The tetrachlorosilane hydrogenation catalyst in this comparative example directly adopts cuprous chloride.

[0154] Comparative Example 3

[0155] The preparation method of the catalyst in this comparative example is basically the same as that in Example 1, except that in step (5), the temperature is adjusted to 550° C. and the holding time is adjusted to 11 h;

[0156] In step (7), the calcination temperature is adjusted to 850° C. and the calcination time is adjusted to 9 h.

[0157] Comparative Example 4

[0158] The preparation method of the catalyst in this comparative example is basically the same as that in Example 1, except that in step (1), the amount of silicon dioxide is adjusted to 16 g.

[0159] Test example

[0160] 1. The catalysts in the above embodiments and comparative examples were subjected to SEM test and TEM test respectively to obtain the particle size of active particles in the catalyst and the thickness of the porous silica shell layer; and the catalysts in the above embodiments and comparative examples were subjected to ICP-OES test to obtain the mass percentage of active particles in the catalyst. The test results are shown in Tables 1 and Figure 2 .

[0161] Figure 2 is the SEM image of the catalyst in Example 1, Figure 2 It can be seen that there are a large number of pores on the catalyst surface, and there are a large number of small particles both on the catalyst surface and inside the pores, which are active particles.

[0162] Table 1

[0163]

[0164]

[0165] From Table 1, we can see that:

[0166] The catalysts in Examples 1 to 23 all have relatively small active particle sizes and a relatively high mass percentage of active particles in the catalyst, with the smallest active particle size being 202 nm and the highest active particle mass percentage in the catalyst being 31.35%. However, the catalysts in Comparative Examples 3 and 4 have too large active particles or too low mass percentages of active particles in the catalyst, with Comparative Example 3 having a relatively high mass percentage of active particles in the catalyst of 26.28 wt%, but a particle size of the active particles of 845 nm; and Comparative Example 4 having a relatively low active particle size of 218 nm, but a mass percentage of active particles in the catalyst of only 17.32%.

[0167] 2. The tetrachlorosilane hydrogenation catalysts prepared in the above examples and comparative examples were subjected to a tetrachlorosilane catalytic conversion experiment, the specific steps of which included:

[0168] The catalyst prepared in the above examples and comparative examples was uniformly mixed with silicon powder, with a mass ratio of the catalyst to the silicon powder of 10:1; the mixture of the catalyst and the silicon powder was introduced into a reactor, and the reactor was purged with nitrogen to exclude air; the temperature of the reactor was raised to a set temperature of 450°C, silicon tetrachloride was injected into the reactor through a metering pump, and mixed with hydrogen, and the feed amount of silicon tetrachloride and hydrogen was adjusted to make the hydrogen-silicon ratio (molar ratio) of 4:1; the reactor pressure was set to 3.0 MPa, the reaction temperature was 450°C, and the online chromatograph was used to measure the reaction temperature of the reactor. The spectrometer monitors the reaction products at the outlet of the reactor in real time to obtain a gas chromatogram; then the conversion rate of silicon tetrachloride (%) = (peak area of ​​dichlorosilane + peak area of ​​trichlorosilane) / (peak area of ​​dichlorosilane + peak area of ​​trichlorosilane + peak area of ​​tetrachlorosilane) × 100%; the change rate of tetrachlorosilane conversion (% / 24h) = (tetrachlorosilane conversion rate when the reaction reaches X hours - tetrachlorosilane conversion rate when the reaction reaches (X+24) hours) / tetrachlorosilane conversion rate when the reaction reaches X hours. The calculation results are shown in Table 1.

[0169] Regeneration: Recover the catalyst after 72 hours of the above reaction, place it in a NaOH solution for alkaline etching, the solution concentration is 0.5 mol / L, the etching time is 30 min, and the water bath temperature is 40°C; after filtering, wash with deionized water until neutral, dry at 120°C for 6 hours, and pass nitrogen gas through the dried product at 0.1 MPa for 1 hour at a flow rate of 50 mL / min for replacement; then pass a mixture of hydrogen and nitrogen at a flow rate of 50 mL / min, set the activation temperature to 300°C, and reduce for 2 hours.

[0170] Recycling and regeneration: After the recycled and regenerated catalyst reacts for 72 hours, the catalyst is recovered and placed in a NaOH solution for alkaline etching with a solution concentration of 0.5 mol / L, an etching time of 30 minutes, and a water bath constant temperature of 40°C; after filtration, it is washed with deionized water until neutral, dried at 120°C for 6 hours, and the dried product is purged with nitrogen at 0.1 MPa for 1 hour at a flow rate of 50 mL / min for replacement; then a mixed gas of hydrogen and nitrogen is introduced at a flow rate of 50 mL / min, the activation temperature is set at 300°C, and reduced for 2 hours.

[0171] The calculation results are shown in Table 2.

[0172] Table 2

[0173]

[0174]

[0175] From Table 2, we can see that:

[0176] The catalysts in Examples 1 to 23 have a higher tetrachlorosilane conversion rate within the first 72 hours, and the conversion rate change rate every 24 hours is low. The conversion rate of the catalyst in Example 8 is 31% when the reaction reaches 24 hours, the conversion rate when the reaction reaches 48 hours, and the conversion rate when the reaction reaches 72 hours is 29. The conversion rate change rate from 24 to 48 hours is 6.45%, and the conversion rate change rate from 48 to 72 hours is 0. The tetrachlorosilane conversion rates of the catalysts in Comparative Examples 1 to 4 are all low in the first 72 hours, not higher than 20%, and the conversion rate change rates of Comparative Examples 1, 3 and 4 from 48 to 72 hours are relatively high, at 15.00%, 17.65% and 16.67%, respectively. It can be seen that the catalyst of the present invention can achieve a higher tetrachlorosilane conversion rate in the hydrogenation reaction and has higher stability. The change rate of the tetrachlorosilane conversion rate during the reaction is no more than 14% / 24h, which can significantly improve the problem of severe decrease in tetrachlorosilane conversion rate and reduce the production cost of polysilicon.

[0177] At the same time, the catalyst of the present invention can be recycled and regenerated after the reaction to expose the unexposed metal active particles in the silica shell layer, thereby improving the reaction activity of the tetrachlorosilane hydrogenation catalyst, achieving recycling and extending the service life of the catalyst.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tetrachlorosilane hydrogenation catalyst, characterized in that The tetrachlorosilane hydrogenation catalyst comprises a porous carrier and active particles supported on the porous carrier, wherein the active particles comprise copper, nickel and cobalt; The particle size of the active particles is not higher than 300 nm, and the mass percentage of the active particles in the tetrachlorosilane hydrogenation catalyst is not lower than 20 wt %; During the hydrogenation reaction process including the tetrachlorosilane hydrogenation catalyst, the change rate of tetrachlorosilane conversion is no higher than 14% / 24h.

2. The tetrachlorosilane hydrogenation catalyst according to claim 1, characterized in that The porous carrier of the tetrachlorosilane hydrogenation catalyst comprises a porous core and a porous silica shell layer located on at least a portion of the surface of the porous core; the porous core and the porous silica shell layer both comprise interconnecting holes connected to the outside, and the active particles are located in the interconnecting holes; The number of the interconnecting pores is 10% to 50% of the number of pores in the porous carrier.

3. The tetrachlorosilane hydrogenation catalyst according to claim 2, characterized in that The thickness of the porous silica shell layer is 1 nm-180 nm.

4. The tetrachlorosilane hydrogenation catalyst according to any one of claims 1 to 3, characterized in that The active particles also include at least one of selenium, molybdenum, iron, chromium, zinc and zirconium.

5. A method for preparing the tetrachlorosilane hydrogenation catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) mixing raw materials including a soluble nickel salt, a soluble copper salt, a soluble cobalt salt, and a porous material with deionized water to obtain a mixed solution; in the mixed solution, the mass percentage of copper is 0.01wt%-10wt%, the mass percentage of cobalt is 0.001wt%-2wt%, and the mass percentage of nickel is 0.001wt%-2wt%; (2) adding a precipitant solution to the mixed solution to perform a precipitation reaction, and maintaining the pH of the reaction system at 8-12. When the pH value is stable, aging is performed at a temperature of 40° C. to 80° C. for 1 h to 15 h. After aging, solid-liquid separation is performed, and the obtained solid phase is washed with water until it is neutral and dried to obtain a first product. (3) After the first product is reduced, a mixture of water vapor and nitrogen is introduced for a first purge; in the first purge, the temperature is 100° C.-200° C., the time is 5 min-30 min, the molar ratio of water vapor to nitrogen is 1:(1-10), the pressure is 0.1 MPa-0.4 MPa, and the volume space velocity of the water vapor and nitrogen is ≥10 h -1 ; (4) introducing a mixture of tetrachlorosilane and nitrogen into the system after the first purge for a second purge; in the second purge, the temperature is 60° C.-80° C., the time is 5 min-30 min, the molar ratio of tetrachlorosilane to nitrogen is 1:(0.1-50), the pressure is 0.1 MPa-0.4 MPa, and the volume space velocity of the tetrachlorosilane gas and the nitrogen is ≥100 h / min respectively. -1 ; (5) In a nitrogen atmosphere, the system after the second purge is subjected to a heating and calcining treatment to obtain a second product; wherein the heating rate is 1°C / min-30°C / min, the calcining temperature is 200°C-500°C, the calcining time is 1h-10h, the pressure is 0.1Mpa-0.4Mpa, and the volume space velocity of nitrogen is ≥100h -1 ; (6) etching the second product with an aqueous solution of sodium hydroxide and / or potassium hydroxide to obtain a third product, wherein the mass concentration of the second product in the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.2 g / mL-1 g / mL; the molar concentration of the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.5 mol / L-6 mol / L, the etching temperature is 20° C.-80° C., and the etching treatment time is 0.5 h-24 h; (7) The third product is washed with water until it is neutral, dried, reduced, and calcined. The calcination temperature is 300° C.-800° C. and the calcination time is 4 h-8 h to obtain the tetrachlorosilane hydrogenation catalyst.

6. The method for preparing a tetrachlorosilane hydrogenation catalyst according to claim 5, characterized in that: In step (2), the precipitant solution is added at a rate of 0.5 mL / min-5 mL / min.

7. The method for preparing a tetrachlorosilane hydrogenation catalyst according to any one of claims 5 or 6, characterized in that: In step (3), the reduction treatment comprises: purging with an inert gas for 0.5 h to 2 h for replacement, and then activating the first product with an activation atmosphere at an activation temperature of 200° C. to 400° C. and a pressure of 0.1 MPa to 0.4 MPa for 1 h to 5 h; The activation atmosphere is a reducing gas, or a mixed gas of a reducing gas and an inert gas in a molar ratio of (0.5-2):

1.

8. The method for preparing a tetrachlorosilane hydrogenation catalyst according to any one of claims 5 to 7, characterized in that: In step (7), the drying temperature is 100°C-120°C, and the drying time is 4h-12h.

9. A method for preparing trichlorosilane, characterized in that: The tetrachlorosilane hydrogenation catalyst described in any one of claims 1 to 4 or the tetrachlorosilane hydrogenation catalyst prepared by the preparation method described in any one of claims 5 to 8 is used in the reaction of hydrogenating tetrachlorosilane to prepare trichlorosilane, so as to prepare trichlorosilane.

10. The method for preparing trichlorosilane according to claim 9, characterized in that: The invention also includes recovering and regenerating the tetrachlorosilane hydrogenation catalyst after the reaction, wherein the recovery and regeneration process includes: Using an aqueous solution of sodium hydroxide and / or potassium hydroxide to etch, wash, dry and reduce the tetrachlorosilane hydrogenation catalyst after the reaction to obtain a recovered tetrachlorosilane hydrogenation catalyst; The molar concentration of the aqueous solution of sodium hydroxide and / or potassium hydroxide is 0.5 mol / L-6 mol / L, the etching temperature is 20° C.-80° C., and the etching treatment time is 0.5 h-24 h.

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