CN105536789A - Method for preparing trichlorosilane catalyst through hydrogenation dechlorination of silicon tetrachloride - Google Patents

Abstract

The invention relates to a catalyst method for preparing trichlorosilane by hydrodechlorination of silicon tetrachloride, using cuprous chloride as an active component and amorphous silicon aluminum as a catalyst carrier. The roasted amorphous silica-alumina powder is mixed with a certain amount of cuprous chloride, treated at high temperature under an inert atmosphere, and the product is cooled to become a finished catalyst. The preparation process of the method is simple, and there is no waste water, waste gas and waste residue pollution. Catalyst evaluation shows that under the process conditions of reaction temperature 450℃, pressure 1.2MPa, H ₂ /SiCl ₄ (mol)=25, and space velocity 1000h ^-1 , the conversion rate can reach more than 30%, which can meet the requirements of industrial production.

Description

A kind of method of the catalyst of silicon tetrachloride hydrogenation dechlorination preparation trichlorosilane

technical field

The invention relates to the field of silicon purification, in particular to a method for preparing a catalyst for hydrogenating silicon tetrachloride to prepare trichlorosilane.

Background technique

The depletion of fossil energy in the future has always plagued the energy industry of countries all over the world. Alternative energy, especially non-polluting and low-cost alternative energy, is the direction of active development of various countries. As a renewable energy source, solar energy has attracted the attention of various countries, and polysilicon as the main raw material of solar cells and its preparation process improvement should become a research hotspot.

At present, the domestic improved Siemens method occupies the mainstream of polysilicon production. The operating conditions of this method are relatively low, but every ton of polysilicon produced will produce more than 10 tons of silicon tetrachloride by-product. In order to reduce the unit consumption of polysilicon production and reduce production The most effective way to reduce costs and avoid environmental hazards is to convert silicon tetrachloride into trichlorosilane, which can be reused as a raw material for polysilicon production. In theory, it can completely achieve pollution-free closed production.

In the process of converting silicon tetrachloride into trichlorosilane using cold hydrogenation technology, the hydrogenation catalyst plays a role in promoting the reaction and increasing the conversion rate of the reaction. A lot of research has been done in the field of catalysts in China, and noble metals can be roughly divided according to the active composition. , nickel, copper. CN102838120 and CN102909006 disclose the use of noble metals as active components of silicon tetrachloride hydrogenation catalysts. CN1436725 discloses a method for hydrogenating silicon tetrachloride to produce trichlorosilane, the nickel catalyst is a powdered hydrogenation nickel catalyst. CN102626630, CN102627283, and CN102626630 disclose a catalyst and its preparation method and application. The preparation process of the catalyst is: a soluble nickel salt, a soluble salt compound of metal M, a silicon source that can provide silicon dioxide, and a catalyst that can precipitate nickel and/or The precipitant of metal M ions is contacted in a solvent, and the obtained product is filtered, dried and calcined. CN101816946 discloses a method for preparing a catalyst for the hydrogenation of silicon tetrachloride and its application. The pretreated cuprous chloride and silicon powder are mixed in a stirred bed reactor and heated under the protection of hydrogen. The pretreatment refers to adding cuprous chloride to silicon tetrachloride, stirring and heating, and drying under protective gas after filtering. CN101941702 discloses a method for producing trichlorosilane by converting tetrachlorosilane, the copper-based supported catalyst includes a carrier and an active component loaded on the carrier, the carrier is silicon dioxide, and the active component is elemental copper , cupric chloride and cuprous chloride, the carrier content is 30%-70%, and the active ingredient content is 30%-70%. CN102350351 discloses a hydrogenation catalyst and a preparation method thereof. The active component of the catalyst is a copper-silicon alloy, a copper-nickel-silicon alloy, a copper-silicon rare-earth alloy or a copper-nickel-silicon rare-earth alloy. The preparation process includes smelting, atomization, reduction drying and sieving. The preparation process of the above-mentioned hydrogenation catalyst is relatively complicated, or the operation process is demanding, which will inevitably lead to an increase in the cost of catalyst preparation. The competition in the field of polysilicon is becoming increasingly fierce, and the control of production costs is becoming more stringent. As an indispensable hydrogenation catalyst in the production process, the price has become a trend. Therefore, the development of low-cost, high-activity hydrogenation catalysts has become an inevitable development in this field.

Contents of the invention

The present invention aims at the problems existing in the above-mentioned prior art, and provides a method for preparing a catalyst for trichlorosilane by hydrodechlorination of silicon tetrachloride, which solves the complicated preparation process of the catalyst for trichlorosilane in the prior art, The problem of high cost.

Catalyst preparation technology provided by the invention comprises the steps:

(1) Amorphous silicon aluminum after roasting, specific surface 150-500m ² /g, pore volume 0.5-1.5mL/g, silicon oxide content 1wt%-90wt%, particle size 40μm-4000μm, mixed with cuprous chloride , The mixing mass ratio is cuprous chloride:amorphous silicon aluminum=2.5～6:1.

(2) Under the protection of an inert gas, the above mixture is heated, the heating rate is 30°C/h-300°C/h, the roasting temperature is 450°C-900°C, the constant temperature time is 1min-300min, and the temperature is naturally lowered after the constant temperature is completed.

In the step (1), the roasted amorphous silicon-alumina is commercially available, and its burnt residue is greater than or equal to 95%. The burnt residue condition: 550° C. for 3 hours at a constant temperature.

In the step (1), the specific surface is preferably 300-400m ² /g; the pore volume is preferably 0.7-1.1mL/g; the silicon oxide content is preferably 5wt%-85wt%; the particle size is preferably 80μm ~2000μm.

In the step (1), the preferred mass ratio of cuprous chloride:amorphous silicon aluminum is 2.8˜5.5:1.

In the step (2), the calcination temperature is preferably 500-800° C., and the constant temperature time is preferably 10 min-60 min. Compared with the prior art, the present invention has advantages and effects:

In the method of the present invention, by mixing amorphous silicon aluminum and cuprous chloride, roasting prepares the catalyst, which has the following advantages:

(1) The method of melting cuprous chloride at high temperature and directly impregnating with molten metal salt effectively avoids the problem of low metal content in a single application during impregnation with water as a solvent.

(2) Using cuprous chloride to melt at high temperature and directly impregnating with molten metal salt effectively avoids problems such as high energy consumption and complicated steps in the impregnation process using water as a solvent.

(3) Utilize cuprous chloride to melt at a high temperature, and directly impregnate by molten metal salt, effectively avoiding when water is used as a solvent, the Cl ^-1 formed when cuprous chloride is dissolved in water has a negative effect on impregnation, stirring, drying, Corrosion of equipment in each section of roasting.

(4) The method of melting cuprous chloride at high temperature and directly impregnating with molten metal salt effectively avoids the discharge of chlorine ion-containing waste gas in the roasting section when water is used as a solvent, and reduces the related pollution control equipment and operation. It also solves the storage and discharge problems of the impregnation waste liquid.

(5) The catalyst prepared by the method can effectively avoid the agglomeration of catalytically active components in the process of hydrodechlorination due to the presence of the carrier.

The preparation method of the catalyst disclosed by the invention is evaluated, and the evaluation results show that the catalyst of the invention has relatively high activity when used for hydrogenating silicon tetrachloride to prepare trichlorosilane.

detailed description

The following examples will further illustrate and illustrate the method provided by the present invention, but do not limit the present invention.

Example 1

(1) Amorphous silicon aluminum after roasting, specific surface 150m ² /g, pore volume 0.7mL/g, silicon oxide content 5wt%, particle size 125μm, mixed with cuprous chloride, the mixing mass ratio is cuprous chloride : Amorphous Si-Al = 2.8:1.

(2) Under the protection of an inert gas, the above mixture was heated with a heating rate of 50°C/h, a calcination temperature of 450°C, and a constant temperature time of 30 minutes. After the constant temperature was completed, the temperature was naturally lowered to obtain a finished catalyst.

Example 2

Others are the same as Example 1, the difference is that in step (2), the temperature during the roasting is 600 degrees centigrade, and the constant temperature is 30min.

Example 3

(1) Amorphous silicon aluminum after roasting, specific surface 500m ² /g, pore volume 1.0mL/g, silicon oxide content 50wt%, particle size 200μm, mixed with cuprous chloride, the mixing mass ratio is cuprous chloride : Amorphous Si-Al = 4.0:1.

(2) Under the protection of an inert gas, the above mixture was heated with a heating rate of 100°C/h, a calcination temperature of 600°C, and a constant temperature time of 60 minutes. After the constant temperature was completed, the temperature was naturally lowered to obtain a finished catalyst.

Example 4

(1) Amorphous silicon aluminum after roasting, specific surface 410m ² /g, pore volume 1.5mL/g, silicon oxide content 30wt%, particle size 300μm, mixed with cuprous chloride, the mixing mass ratio is cuprous chloride : Amorphous Si-Al = 5.6:1.

(2) Under the protection of an inert gas, the above mixture was heated at a heating rate of 100°C/h, a calcination temperature of 800°C, and a constant temperature time of 30 minutes. After the constant temperature was completed, the temperature was naturally lowered to obtain a finished catalyst.

Example 5

(1) Amorphous silicon aluminum after roasting, specific surface 150m ² /g, pore volume 0.5mL/g, silicon oxide content 1wt%, particle size 40μm, mixed with cuprous chloride, the mixing mass ratio is cuprous chloride : Amorphous Si-Al = 2.5:1.

(2) Under the protection of an inert gas, the above mixture was heated with a heating rate of 30°C/h, a calcination temperature of 450°C, and a constant temperature time of 300min. After the constant temperature was completed, the temperature was naturally lowered to obtain a finished catalyst.

Example 6

(1) Amorphous silicon aluminum after roasting, specific surface ≥ 150m ² /g, pore volume ≥ 0.5mL/g, silicon oxide content 90wt%, particle size 4000μm, mixed with cuprous chloride, the mixing mass ratio is Cuprous: amorphous silicon aluminum = 6:1.

(2) Under the protection of an inert gas, the above mixture was heated at a heating rate of 300 °C/h, a calcination temperature of 900 °C, and a constant temperature time of 1 min. After the constant temperature was completed, the temperature was naturally lowered to obtain a finished catalyst.

Example 7

In the step (1), the roasted amorphous silicon-alumina is commercially available, and its burnt residue is 95%. The burnt residue conditions are: constant temperature at 550°C for 3 hours; specific surface area 300m ² /g; pore volume 0.7mL/g; oxidation The silicon content is 5 wt %; the particle size is 80 μm; the mass ratio of cuprous chloride: amorphous silicon aluminum is 2.8:1. Under the protection of an inert gas, the above mixture was heated at a calcination temperature of 500° C. and a constant temperature time of 10 minutes. Other steps are the same as in Example 1.

Example 8

In the step (1), the roasted amorphous silicon-alumina is commercially available, and its burnt residue is ≥95%. The burnt residue conditions are: constant temperature at 550°C for 3 hours; specific surface area: 300m ² /g; pore volume: 0.7mL/g; The silicon oxide content is 85wt%; the particle size is 2000 μm; the mass ratio of cuprous chloride: amorphous silicon aluminum is 5.5:1. Under the protection of an inert gas, the above mixture was heated, the calcination temperature was 800° C., and the constant temperature time was 60 minutes. Other steps are the same as in Example 1.

Example 9

The catalysts prepared in the above-mentioned Examples 1-8 are used for evaluation, and the evaluation process conditions are as follows: a fixed-bed reactor, at a certain reaction temperature, a pressure of 1.2 MPa, H ₂ /SiCl ₄ (mol)=25, and a process with a space velocity of 1000 h ⁻¹ Under the condition, measure the product when reacting 20h, calculate the conversion rate of silicon tetrachloride, the conversion rate of silicon tetrachloride described in the present embodiment is defined as:

The invention provides a catalyst for preparing trichlorosilane by hydrodechlorination of tetrahydrogen silicon and a preparation method thereof. The preparation process of the method is simple and free from waste water, waste gas and waste residue pollution. The catalyst uses cuprous chloride as an active component, and amorphous silica-alumina as a catalyst carrier. The roasted amorphous silica-alumina powder is mixed with a certain amount of cuprous chloride, treated at high temperature under an inert atmosphere, and the product is cooled to become a finished catalyst. Catalyst evaluation shows that under the process conditions of reaction temperature 450°C, pressure 1.2MPa, H ₂ /SiCl ₄ (mol)=25, and space velocity 1000h ^-1 , the conversion rate can reach 30%, which can meet the requirements of industrial production.

The evaluation data of different embodiments of table 1

Claims (5)

1. a method for preparing the catalyst of trichlorosilane by hydrodechlorination of silicon tetrachloride, is characterized in that comprising the steps: (1) Amorphous silicon aluminum after roasting, specific surface 150-500m ² /g, pore volume 0.5-1.5mL/g, silicon oxide content 1wt%-90wt%, particle size 40μm-4000μm, mixed with cuprous chloride , The mixing mass ratio is cuprous chloride:amorphous silicon aluminum=2.5～6:1. (2) Under the protection of inert gas, the above mixture is heated, the heating rate is 30°C/h-300°C/h, the roasting temperature is 450°C-900°C, the constant temperature time is 1min-300min, and the temperature is naturally lowered after the constant temperature is completed. 2. A method for preparing a catalyst for trichlorosilane by hydrodechlorination of silicon tetrachloride according to claim 1, characterized in that in the step (1), the roasted amorphous silicon aluminum is commercially available Commodity, its burning residue ≥ 95%, burning residue condition: 550°C, 3h. 3. A method for preparing trichlorosilane catalyst by hydrodechlorination of silicon tetrachloride according to claim 1, characterized in that in the step (1), the specific surface area is preferably 300-400m ² /g ; The pore volume is preferably 0.7-1.1mL/g; the silicon oxide content is preferably 5wt%-85wt%; the particle size is preferably 80μm-2000μm. 4. A method for preparing a catalyst for trichlorosilane by hydrodechlorination of silicon tetrachloride according to claim 1, characterized in that in the step (1), cuprous chloride: amorphous silicon aluminum The preferred mass ratio is 2.8-5.5:1. 5. A method for preparing a catalyst for trichlorosilane by hydrodechlorination of silicon tetrachloride according to claim 1, characterized in that in the step (2), the roasting temperature is preferably 500-800°C, and the constant temperature time is Preferably 10min～60min.