Device for preparing silane from mixed chlorosilane

Abstract

The utility model relates to a device for preparing pure silane from mixed chlorosilane, which comprises a silicon tetrachloride separation tower, a chlorosilane adsorption column, a silane reaction tower, a silane de-heavy tower, a silane adsorption column and a silane refining tower which are sequentially connected in series, and an upper end outlet of the silicon tetrachloride separation tower is connected with a lower end inlet of the chlorosilane adsorption column; an upper end outlet of the chlorosilane adsorption column is connected with a raw material inlet of the silane reaction tower; an upper end outlet of the silane reaction tower is connected with a raw material inlet of the silane heavy component removal tower; an upper end outlet of the silane heavy component removal tower is connected with a gas phase inlet of the silane adsorption column, and a lower end outlet of the silane heavy component removal tower returns to the middle part of the silane reaction tower; a gas phase outlet of the silane adsorption column is connected with a raw material inlet of the silane refining tower; and an electronic-grade high-purity silane product is obtained at a side line outlet of the silane refining tower. The device is suitable for continuous production of kiloton-grade high-purity silane and continuous production of kiloton-grade high-purity silane, and the energy consumption and the operation cost in the process can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and particularly relates to a device for preparing silane from mixed chlorosilane. Background Art

[0002] Silane (SiH4) is a colorless gas and one of the main raw materials for preparing polysilicon by the silane method. The polysilicon prepared by this method has high purity and a simple process flow. In addition, high-purity silane is also a commonly used electronic special gas in industries such as photovoltaics and semiconductors.

[0003] At present, the main preparation methods of silane include silicon-magnesium alloy method, sodium aluminum fluoride method and chlorosilane disproportionation method. Among them, the chlorosilane disproportionation method is that trichlorosilane undergoes a three-step reversible disproportionation reaction under the action of a catalyst to produce silane and silicon tetrachloride. Silicon tetrachloride can be further hydrogenated into raw material trichlorosilane through cold hydrogenation, thermal hydrogenation and catalytic hydrogenation. The whole process operates in a closed loop, no by-products are produced and the atomic utilization rate is high. It is a "green" process and has gradually become the mainstream production method of silane.

[0004] UCC Corporation of the United States first proposed a process for preparing high-purity silane using the chlorosilane disproportionation method in its patent US4340574. This process uses a fixed bed to carry out multi-step disproportionation reaction and combines it with a distillation purification process to prepare high-purity silane. Due to the limitation of reaction equilibrium, the TCS single-pass conversion rate of this method is less than 10wt%, with low production efficiency, high energy consumption and investment.

[0005] Patent CN103172071 discloses a method for preparing high-purity silane by disproportionation reaction distillation of trichlorosilane, which includes a disproportionation reaction distillation process, a silicon tetrachloride absorption process, a fixed bed adsorption process and a product canning process. The process is complicated, mainly separating the silane product by absorption, the product purity is low, and it involves problems such as absorbent regeneration and adsorbent saturation.

[0006] Patent CN106241813 discloses a system and method for producing high-purity silane from trichlorosilane, including a reaction tower, a multi-stage condenser, a compressor, a silane refining tower and a product tower. Since the crude silane entering the compressor has many components and large boiling point differences, it will cause liquefaction in the compressor cylinder, affecting the normal operation of the compressor, and further leading to frequent compressor maintenance, which is extremely detrimental to the safe production of enterprises. Utility Model Content

[0007] [Technical issues to be solved]

[0008] In view of the above defects existing in the existing devices, the purpose of the utility model is to provide a device for preparing silane from mixed chlorosilane, using mixed chlorosilane synthesized by cold hydrogenation as raw material, and preparing high-purity silane through a silicon tetrachloride separation tower, a chlorosilane adsorption column, a silane reaction tower, a silane deweighting tower, a silane adsorption column and a silane refining tower connected in series in sequence. Compared with the existing device, the utility model has a high silane yield and high purity, can meet the continuous production of electronic grade high-purity silane with a capacity of 1,000 tons or more, and can effectively reduce energy consumption and operating costs in the process.

[0009]

Technical solution

[0010] In order to achieve the above-mentioned purpose of the invention, the utility model adopts the following technical scheme.

[0011] A device for preparing silane from mixed chlorosilanes comprises a silicon tetrachloride separation tower, a chlorosilane adsorption column, a silane reaction tower, a silane weight removal tower, a silane adsorption column and a silane refining tower which are sequentially connected in series. The mixed chlorosilane [1] synthesized by cold hydrogenation is connected to the raw material inlet of the feed side of the silicon tetrachloride separation tower [A], and the top outlet of the silicon tetrachloride separation tower [A] is connected to the lower inlet of the chlorosilane adsorption column [B]; the upper outlet of the chlorosilane adsorption column [B] is connected to the raw material inlet of the silane reaction tower [C]; the upper outlet of the silane reaction tower [C] is connected to the raw material inlet of the silane deweighting tower [D]; the upper outlet of the silane deweighting tower [D] is connected to the gas phase inlet of the silane adsorption column [E], and the lower outlet of the silane deweighting tower [D] returns to the middle of the silane reaction tower [C]; the gas phase outlet of the silane adsorption column [E] is connected to the raw material inlet of the silane refining tower [F]; the side line outlet of the silane refining tower [F] obtains an electronic grade high-purity silane product. The specific steps are as follows:

[0012] (1) The mixed chlorosilane [1] synthesized by cold hydrogenation enters the middle of the silicon tetrachloride separation tower [A], the distillate from the top of the tower [2] flows into the bottom of the chlorosilane adsorption column [B], the side silicon tetrachloride [3] flows into the silicon tetrachloride storage tank, and the bottom liquid [4] flows into the high boiling point storage tank;

[0013] (2) The overflow liquid [5] from the top of the chlorosilane adsorption column [B] enters the middle of the silane reaction tower [C];

[0014] (3) The top distillate [6] of the silane reaction tower [C] enters the middle of the silane deweighting tower [D], and the bottom liquid [7] flows into the silicon tetrachloride storage tank;

[0015] (4) The top vapor phase [8] of the silane deweighting tower [D] enters the top of the silane adsorption column [E]; the bottom liquid [9] of the tower returns to the middle of the silane reaction tower [C];

[0016] (5) The gas phase

[10] at the bottom of the silane adsorption column [E] enters the middle of the silane refining tower [F];

[0017] (6) The tail gas

[11] at the top of the silane refining tower [F] is incinerated, the side-line gaseous silane

[12] is condensed and enters the high-purity silane product storage tank, and the heavy impurities

[13] in the bottom of the tower are incinerated.

[0018] The silicon tetrachloride separation tower [A] is a baffle distillation tower, the common distillation section height is 10-30m, the baffle section height is 10-20m, the common stripping section height is 4-6m, and structured packing, trays or structured packing-tray composite are used as separation elements. The reflux ratio is 1-10:1, the operating temperature is 50-140°C, and the operating pressure is 0.3-0.8MPag.

[0019] The chlorosilane adsorption column [B] is equipped with a solid adsorbent for removing impurities such as boron, phosphorus, carbon, and metals in trichlorosilane. The solid adsorbent is composed of one or more of resin, activated carbon, and molecular sieve. The bed height of the chlorosilane adsorption column is 4 to 8 meters, the operating temperature is -20 to 40°C, and the operating pressure is 0.1 to 1.0 MPa.

[0020] The silane reaction tower [C] is a reaction distillation tower, which is divided into three sections from top to bottom, namely, upper, middle and lower sections, and each section is blocked by a head. The middle and lower sections of the tower are equipped with catalyst layers, and the upper and lower sections of the tower are equipped with high-efficiency structured packing. The packing layer height of the distillation section and the stripping section of the silane reaction tower is 4 to 6 meters, and the height of the catalyst layer of the two sections is 4 to 6 meters. Intermediate condensers are provided at the upper part of the middle section and the upper part of the lower section of the silane reaction tower. The reflux ratio is 0.1 to 3:1, the operating temperature is -80 to 120°C, and the operating pressure is 0.3 to 0.8MPag.

[0021] The silane deweighting tower [D] has a rectifying section of 4 to 6 m and a stripping section of 3 to 5 m, and uses structured packing, trays or a combination of structured packing and trays as separation elements. The reflux ratio is 3 to 6:1, the operating temperature is -30 to 120°C, and the operating pressure is 2.0 to 3.0 MPag.

[0022] The silane adsorption column [E] is equipped with a solid adsorbent for removing impurities such as alkanes, boron, phosphorus, etc. in silane. The solid adsorbent is composed of one or more of resin, silica gel and molecular sieve. The bed height of the silane adsorption column is 4 to 8 meters, the operating temperature is -50 to 10°C, and the operating pressure is 2.0 to 3.0 MPa.

[0023] The silane refining tower [F] has a rectifying section of 3 to 5 m and a stripping section of 4 to 6 m, and uses structured packing, trays or a combination of structured packing and trays as separation elements. The reflux ratio is 350 to 450:1, the operating temperature is -30 to -10°C, and the operating pressure is 2.0 to 3.0 MPag.

[0024] The beneficial effects of the utility model are:

[0025] The utility model provides a device for preparing silane from mixed chlorosilane, comprising a silicon tetrachloride separation tower, a chlorosilane adsorption column, a silane reaction tower, a silane weight removal tower, a silane adsorption column and a silane refining tower which are sequentially connected in series, optimizes the silane production device, improves the disproportionation reaction conversion rate and the silane product quality, reduces the energy consumption and operating costs in the process, and the utility model can effectively meet the continuous production of electronic grade high-purity silane with a capacity of 1,000 tons or more. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The utility model is further described in detail below with reference to the accompanying drawings.

[0027] Figure 1 The utility model discloses a device for preparing silane from mixed chlorosilane.

[0028] In the figure:

[0029] A. Silicon tetrachloride separation tower, B. Chlorosilane adsorption column, C. Silane reaction tower, D. Silane deweighting tower, E. Silane adsorption column, F. Silane refining tower.

[0030] 1. Cold hydrogenation raw materials, 2. Silicon tetrachloride separation tower [A] top distillate, 3. Silicon tetrachloride separation tower [A] side line silicon tetrachloride, 4. Silicon tetrachloride separation tower [A] bottom liquid, 5. Chlorosilane adsorption column [B] top overflow liquid, 6. Silane reaction tower [C] top distillate, 7. Silane reaction tower [C] bottom liquid, 8. Silane deweighting tower [D] top vapor phase, 9. Silane deweighting tower [D] bottom liquid, 10. Silane adsorption column [E] bottom gas phase, 11. Silane refining tower [F] top light components, 12. Silane refining tower [F] side line gas phase silane, 13. Silane refining tower [F] bottom heavy components. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the utility model more clearly understood, the device of the utility model is described below in conjunction with the drawings and specific embodiments, but the drawings and specific embodiments do not constitute a limitation to the utility model. Specific embodiment 1:

[0033] The calculation is explained based on a pilot-scale project with an annual output of 10 tons of high-purity silane.

[0034] A device for preparing silane from mixed chlorosilanes comprises a silicon tetrachloride separation tower, a chlorosilane adsorption column, a silane reaction tower, a silane deweighting tower, a silane adsorption column and a silane refining tower connected in series in sequence. Specifically, the following steps are included:

[0035] (1) 79.64 kg / h of cold hydrogenation synthesized mixed chlorosilane [1] (the raw material composition is 5.85 wt% dichlorosilane, 26.17 wt% trichlorosilane, and 73.23 wt% silicon tetrachloride) enters the middle of the silicon tetrachloride separation tower [A], 21.3 kg / h of distillate [2] at the top of the tower flows into the bottom of the chlorosilane adsorption column [B], 57 kg / h of silicon tetrachloride [3] from the side line flows into the silicon tetrachloride storage tank, and 1.34 kg / h of high boiling products [4] at the bottom of the tower are discharged from the discharge device;

[0036] (2) 21.3 kg / h of material [5] at the top of the chlorosilane adsorption column [B] enters the middle of the silane reaction tower [C];

[0037] (3) 2.848 kg / h of distillate [6] from the top of the silane reaction tower [C] enters the middle of the silane deweighting tower [D], and 20.04 kg / h of the bottom liquid [7] flows into the silicon tetrachloride storage tank;

[0038] (4) 1.26 kg / h of gas phase [8] at the top of the silane deweighting tower [D] enters the top of the silane adsorption column [E], and 1.588 kg / h of the bottom liquid [9] returns to the middle of the silane reaction tower [C];

[0039] (5) The 1.26 kg / h gas phase

[10] at the bottom of the silane adsorption column [E] enters the middle of the silane refining tower [F];

[0040] (6) 0.005 kg / h of light components discharged from the top of the silane refining tower [F] are sent to incineration, 1.25 kg / h of gaseous materials

[12] from the side line are condensed and flow into the high-purity silane product storage tank, and 0.005 kg / h of heavy components

[13] from the bottom of the tower are discharged to incineration.

[0041] The silicon tetrachloride separation tower [A] is a baffle distillation tower, the upper distillation section height is 10m, the middle baffle section height is 15m, the lower stripping section height is 4m, and the tower uses high-efficiency structured packing. The reflux ratio is 3.9:1, the operating temperature is 76-121°C, and the operating pressure is 0.4MPag. A trichlorosilane mixture with a purity of 97.75wt% is obtained from the top of the chlorosilane distillation tower, and silicon tetrachloride with a purity of 99.96wt% is obtained from the side line, and high boiling products in silicon tetrachloride are discharged from the bottom of the tower.

[0042] The chlorosilane adsorption column [B] is loaded with a resin adsorbent for removing impurities such as boron, phosphorus, carbon, and metals in trichlorosilane. The bed height of the chlorosilane adsorption column [B] is 6m, the operating temperature is -10 to 10°C, and the operating pressure is 0.6MPag.

[0043] The silane reaction tower [C] is a reaction distillation tower, which is divided into three sections: upper, middle and lower, and each section is blocked by a head. The middle and lower sections of the tower are equipped with catalyst layers, and the upper and lower sections of the tower are equipped with high-efficiency structured packing. The upper middle section and the upper lower section of the silane reaction tower [C] are both provided with intermediate condensers. The silane reaction tower [C] uses dichlorosilane or trichlorosilane as raw materials, and after multi-step disproportionation reaction and separation, crude silane is obtained from the top of the silane reaction tower [C]. The silicon tetrachloride obtained from the bottom of the tower is mixed with the side line material of the chlorosilane separation tower [A] and sent to the hydrogenation section for recycling.

[0044] The packing layer height of the rectifying section of the silane reaction tower [C] is 4m, the packing layer height of the stripping section is 4m, and the height of the two catalyst layers is 4m. The rectifying section and the stripping section use high-efficiency structured packing. The reflux ratio is 0.64:1, the operating temperature is -72 to 113°C, and the operating pressure is 0.32MPag. Crude silane with a silane content of 44.3wt% is obtained from the top of the silane reaction tower [C], and 99.78wt% of silicon tetrachloride is obtained from the bottom of the tower.

[0045] The silane deweighting tower [D] has a rectifying section of 5 m and a stripping section of 4 m, uses high-efficiency structured packing, a reflux ratio of 3.4:1, an operating temperature of -24 to 107°C, and an operating pressure of 2.7 MPag. Silane with a content of 99.999% is obtained from the top of the silane deweighting tower [D], and the mixed chlorosilane separated from the bottom of the tower is returned to the middle of the silane reaction tower [C] to continue the disproportionation reaction.

[0046] The silane adsorption column [E] is equipped with silica gel adsorbent to remove impurities such as alkanes, boron, phosphorus, etc. in silane. The bed height of the silane adsorption column is 4 to 8 meters, the operating temperature is -24°C, and the operating pressure is 2.6MPag.

[0047] The silane refining tower [F] has a rectifying section of 4 m and a stripping section of 5 m, uses high-efficiency structured packing, a reflux ratio of 380:1, an operating temperature of -30 to -28°C, and an operating pressure of 2.4 MPag. The light components in the silane are removed from the top of the silane refining tower [F], the heavy components in the silane are removed from the bottom of the tower, and high-purity silane with a purity greater than 99.9999wt% is extracted from the side gas phase, meeting the quality indicators of electronic-grade silane specialty gas.

[0048] Example 1 The output of high-purity silane (6N) is 1.25 kg / h, and the utilities consumed are:

[0049] (1) 0.3MPaG saturated steam (143℃): 1.01×104kcal / h;

[0050] (2) Circulating water (30°C inlet, 40°C outlet): 6.86×103 kcal / h;

[0051] (3) Methanol-water solution (-40°C inlet, -35°C outlet): 1.92×103 kcal / h;

[0052] (4) -100℃ refrigerant: 4.28×102kcal / h. Specific embodiment 2:

[0054] The calculation is described based on an industrial-scale project with an annual output of 5,000 tons of high-purity silane. Except for the following material balance, which is different from Example 1, the rest is consistent with Example 1:

[0055] (1) 39,820 kg / h of cold hydrogenation synthesized mixed chlorosilane [1] (raw material composition: 5.85 wt% dichlorosilane, 26.17 wt% trichlorosilane, 73.23 wt% silicon tetrachloride) enters the middle of the silicon tetrachloride separation tower [A], 10,650 kg / h of distillate [2] from the top of the tower flows into the bottom of the chlorosilane adsorption column [B], 28,500 kg / h of silicon tetrachloride [3] from the side line flows into the silicon tetrachloride storage tank, and 670 kg / h of the bottom liquid [4] flows into the high boiling point storage tank;

[0056] (2) 10,650 kg / h of material [5] from the top of the chlorosilane adsorption column [B] enters the middle of the silane reaction tower [C];

[0057] (3) 1,424 kg / h of distillate [6] from the top of the silane reaction tower [C] enters the middle of the silane deweighting tower [D], and 10,020 kg / h of the bottom liquid [7] flows into the silicon tetrachloride storage tank;

[0058] (4) 630 kg / h of gas phase [8] at the top of the silane deweighting tower [D] enters the top of the silane adsorption column [E], and 794 kg / h of the bottom liquid [9] returns to the middle of the silane reaction tower [C];

[0059] (5) The 630 kg / h gas phase

[10] at the bottom of the silane adsorption column [E] enters the middle of the silane refining tower [F];

[0060] (6) 2.0 kg / h of light components

[11] from the top of the silane refining tower [F] are sent to incineration, 625 kg / h of gaseous materials

[12] from the side line are condensed and flow into the high-purity silane product storage tank, and 3 kg / h of heavy components

[13] from the bottom of the tower are sent to the flare for incineration.

[0061] Example 2 The output of high-purity silane (6N) is 625 kg / h, and the utilities consumed are:

[0062] (1) 0.3MPaG saturated steam (143℃): 5.04Gcal / h;

[0063] (2) Circulating water (30°C inlet, 40°C outlet): 3.43 Gcal / h;

[0064] (3) Methanol-water solution (-40°C inlet, -35°C outlet): 0.961 Gcal / h;

[0065] (4) -100℃ refrigerant: 0.214Gcal / h.

[0066] In combination with Specific Example 1 and Example 2, thanks to the introduction of energy-saving technologies and devices such as baffle distillation towers, reactive distillation towers and intermediate condensation processes, the steam consumption of a device for preparing silane from mixed chlorosilane presented in the utility model can be reduced to 8.1×103 kcal steam / kg silane. In addition, the consumption of low-temperature refrigerants and cryogens can be reduced by 15% to 20% compared with existing production technologies. The introduction of reactive distillation technology and high-efficiency adsorbents can improve the silane disproportionation conversion rate and product quality of the utility model, and at the same time has the significant advantages of high recovery rate, low equipment investment, and energy saving.

[0067] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model 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 various embodiments of the utility model.

Claims

1. A device for preparing silane from mixed chlorosilanes, characterized in that The invention comprises a silicon tetrachloride separation tower, a chlorosilane adsorption column, a silane reaction tower, a silane deweighting tower, a silane adsorption column and a silane refining tower which are sequentially connected in series; the mixed chlorosilane synthesized by cold hydrogenation is connected to the raw material inlet of the silicon tetrachloride separation tower feed side, the top outlet of the silicon tetrachloride separation tower is connected to the lower inlet of the chlorosilane adsorption column, the upper outlet of the chlorosilane adsorption column is connected to the raw material inlet of the silane reaction tower, the upper outlet of the silane reaction tower is connected to the raw material inlet of the silane deweighting tower, the upper outlet of the silane deweighting tower is connected to the gas phase inlet of the silane adsorption column, the lower outlet of the silane deweighting tower is returned to the middle of the silane reaction tower, the gas phase outlet of the silane adsorption column is connected to the raw material inlet of the silane refining tower, and the side line outlet of the silane refining tower obtains an electronic grade high-purity silane product.

2. The device for preparing silane from mixed chlorosilane according to claim 1, characterized in that: The silicon tetrachloride separation tower is a partition distillation tower, the common distillation section height is 10-30m, the partition section height is 10-20m, the common stripping section height is 4-6m, and structured packing, tower tray or structured packing-tower tray composite form is used as separation element.

3. The device for preparing silane from mixed chlorosilane according to claim 1, characterized in that: The silane reaction tower is a reaction distillation tower, which is divided into three sections from top to bottom: upper, middle and lower sections, each section is blocked by a head, the middle section and the lower section of the tower are equipped with catalyst layers, and the upper section and the lower section of the tower are equipped with high-efficiency structured packing; the packing layer height of the distillation section and the stripping section of the silane reaction tower is 4~6m, and the height of the catalyst layer of the two sections is 4~6m; the upper part of the middle section and the upper part of the lower section of the silane reaction tower are both provided with intermediate condensers.

4. The device for preparing silane from mixed chlorosilane according to claim 1, characterized in that: The silane deweighting tower has a rectifying section of 4-6 m and a stripping section of 3-5 m, and uses structured packing, tower trays or a structured packing-tower tray composite as a separation element.

5. The device for preparing silane from mixed chlorosilanes according to claim 1, characterized in that: The silane refining tower has a rectifying section of 3-5 m and a stripping section of 4-6 m, and uses structured packing, tower trays or a composite of structured packing and tower trays as separation elements.

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