Method for separating electronic-grade tetramethylsilane and application

Abstract

The invention discloses a method for separating electronic-grade tetramethylsilane and application. The method comprises the following steps: obtaining a raw material gas crude product after dehydrogenation and heavy component removal; the raw material gas crude product is sequentially subjected to adsorption purification through a polar adsorption part and a volume adsorption part, the polar adsorption part at least comprises a polar adsorbent, the volume adsorption part at least comprises a porous adsorbent, and the polar adsorbent is selected to have selective polar adsorption on 2-chloropropane; the porous adsorbent is selected to have selective volume adsorption on isopentane. According to the invention, two types of molecular sieve adsorbents are combined for use, so that the common problem of high energy consumption of purification by connecting multiple rectifying towers in series in organic silicon production is solved, and the content of isopentane is directly reduced to be less than 10ppm; the experimental conditions are not harsh, the energy consumption is low, the molecular sieve can be regenerated and reused, and the economical efficiency is high.

Description

Technical Field

[0001] The invention belongs to the technical field of special gases, and specifically relates to a method for separating electronic-grade tetramethylsilane from low-boiling organic silicon products and application thereof. Background Art

[0002] At a time when the semiconductor industry is developing rapidly, electronic-grade ultrapure precursor materials are key raw materials in the semiconductor manufacturing process, and their quality and technical content directly affect the performance and quality of the final semiconductor products. At present, the demand for such materials is increasing both at home and abroad, especially tetramethylsilane (TMS), which, as one of the important electronic gases, plays an indispensable role in the field of semiconductor manufacturing.

[0003] However, in the Chinese market, although there are many TMS manufacturers, there are still very few companies that can produce high-purity electronic-grade TMS products for direct use by semiconductor manufacturers. This has, to a certain extent, limited the autonomy and competitiveness of my country's semiconductor industry in terms of raw materials.

[0004] At present, the methods for preparing tetramethylsilane on the market are mainly based on chemical reactions in the source of its raw materials. For example, tetrachlorosilane or ethyl orthosilicate reacts with methyl magnesium iodide or methyl chloride and silicon powder react in the presence of a copper catalyst, but there are still many problems in purification. The difficulty in purifying tetramethylsilane (TMS) lies mainly in the fact that its boiling point is very close to that of impurities. For example, under standard atmospheric pressure, the boiling point of tetramethylsilane is 26.6°C, while the boiling points of some impurities such as 2-methylbutane are 27.9°C, 1-pentene is 29.9°C, and 2-methyl-1-butene is 31.2°C, which makes it very difficult to purify using distillation.

[0005] Therefore, in view of the above technical problems, it is necessary to provide a method and application of separating electronic grade tetramethylsilane.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a method for separating electronic grade tetramethylsilane and application thereof.

[0008] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0009] The method for separating electronic grade tetramethylsilane from low-boiling organic silicon products comprises:

[0010] Obtaining a crude liquid raw material product after light and heavy removal;

[0011] The raw gas crude product is sequentially adsorbed and purified by a polar adsorption part and a volume adsorption part, wherein the polar adsorption part at least includes a polar adsorbent, and the volume adsorption part at least includes a porous adsorbent. The polar adsorbent is selected to have selective polar adsorption for 2-chloropropane, and the porous adsorbent is selected to have selective volume adsorption for isopentane.

[0012] In one or more embodiments of the present invention, the raw gas product comprises v / v%: 80-87% tetramethylsilane, 9.6-14.5% isopentane, 2.2-5.5% 2-chloropropane and the remainder of other impurities.

[0013] In one or more embodiments of the present invention, the polar adsorbent is selected from zeolite molecular sieves and 13X molecular sieves.

[0014] In one or more embodiments of the present invention, the polar adsorbent is 13X molecular sieve.

[0015] In one or more embodiments of the present invention, the porous adsorbent is selected from ZSM-5 zeolite molecular sieve and 5A molecular sieve.

[0016] In one or more embodiments of the present invention, the porous adsorbent is ZSM-5 zeolite molecular sieve.

[0017] In one or more embodiments of the present invention, the polar adsorption part and the volume adsorption part are different molecular sieve filling parts arranged in the same adsorption column, and the filling amount ratio of the polar adsorption part and the volume adsorption part satisfies the composition ratio of tetramethylsilane and target impurities in the raw gas crude product (based on the product stably extracted from the top of the distillation tower, obtained through chromatographic analysis).

[0018] In one or more embodiments of the present invention, the conditions for adsorption purification are: temperature of 30-40° C. and pressure of slightly negative pressure to slightly positive pressure.

[0019] In one or more embodiments of the present invention, the pressure is 0.06-0.15 MPaG. Preferably, the adsorbent can be regenerated after completing the adsorption operation, and the regeneration pressure of the adsorbent is -0.1 MPaG.

[0020] In one or more embodiments of the present invention, the method for separating electronic-grade tetramethylsilane from low-boiling organic silicon products is used in the preparation of electronic-grade tetramethylsilane.

[0021] Compared with the prior art, the method for separating electronic-grade tetramethylsilane and its application of the present invention aim at the problem that the current industrial direct synthesis of tetramethylsilane is not economical enough. The industrial tail gas (tetramethylsilane content is about 50%, and other impurities are alkanes, olefins and halogenated hydrocarbons) enriched after industrial preparation of methylchlorosilane (the main product is dimethyldichlorosilane, and the secondary products are organic chlorosilanes such as methyltrichlorosilane, trimethylchlorosilane and monomethyldichlorosilane) is selected as an industrial raw material, and most of the heavy components are removed by a single distillation. Finally, all other impurities are removed by adsorption by combining two molecular sieves, so as to obtain electronic-grade tetramethylsilane with a component content of 99.99%, which can be used as an organic silicon source to meet the needs of chemical vapor deposition (CVD) and atomic layer deposition (ALD) in the semiconductor industry.

[0022] The present invention combines two types of molecular sieve adsorbents, and the crude product only passes through a packing tower adsorption process once to directly obtain electronic grade tetramethylsilane (TMS) (component purity 4N), thereby overcoming the high energy consumption problem of multiple distillation towers in series purification commonly used in organosilicon production, and directly reducing the isopentane content to below 10 ppm; the experimental conditions are not harsh, the energy consumption is low, the molecular sieve can be regenerated and reused, and the economy is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 The figure is a schematic diagram of the purification process of the method for separating electronic grade tetramethylsilane in one embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only 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 should fall within the scope of protection of the present invention.

[0026] The raw materials required for the synthesis of tetramethylsilane are expensive, and the conditions required for separation and purification are harsh and energy-intensive. The present invention selects industrial tail gas from industrial synthesis of methylchlorosilane as the initial raw material, which conforms to the concept of green and economical invention and is extremely environmentally friendly.

[0027] The content of tetramethylsilane (TMS) in the initial raw material is about 50-60%. The present invention first removes some impurities through a distillation tower to obtain a crude product. The content ratio of each component in the crude product is about tetramethylsilane (TMS) tetramethylsilane (77-87%), isopentane (8-15%), 2-chloropropane (2-8%) and other impurities. At this time, the boiling point difference of the main components is very small, such as TMS (26.7°C) and isopentane (27.7°C), and other components are azeotropic with tetramethylsilane (TMS). Purification by distillation requires a very high theoretical plate number, high separation cost, or even no purification at all. In addition to distillation purification, molecular sieve adsorption is one of the main methods of separation and purification.

[0028] The 2-chloropropane and trace heavy components in the crude product co-exist with tetramethylsilane (TMS) and are difficult to separate by further distillation. However, the polarity of 2-chloropropane is larger than that of other components and can be removed by adsorption with the polar adsorbent 13X. At this time, the main impurities isopentane and tetramethylsilane (TMS) are very similar in polarity, solubility, reactivity, etc. except for the boiling point, with only a slight difference in molecular structure (tetramethylsilane Isopentane ), the present invention utilizes its volume difference and selects the molecular sieve ZSM-5 with suitable pore size as the adsorbent. The ZSM-5 zeolite molecular sieve has a regular pore structure and a suitable pore size (0.51-0.56 nm), which can effectively adsorb isopentane and effectively separate tetramethylsilane.

[0029] The present invention combines two functional adsorbents 13X and ZSM-5 molecular sieves, and loads the two molecular sieves into an adsorption column. All impurities in the crude product can be directly removed by one adsorption under simple conditions of 30-40°C and slightly negative pressure to slightly positive pressure, and the purity of the obtained tetramethylsilane (TMS) component is 99.99% (4N). The effective treatment capacity of molecular sieve 13X for 2-chloropropane can reach 100 mg / g, and the effective treatment capacity of molecular sieve ZSM-5 for isopentane can reach 80 mg / g. The present invention calculates and proportions the filling ratio of 13X and ZSM-5 according to the composition ratio of tetramethylsilane (TMS) and its impurity components in the raw material, loads the adsorption column, and directly extracts the product, which is analyzed as a 4N product by gas chromatography GC-MS. The molecular sieves can be reused through a regeneration process.

[0030] The schematic diagram of the adsorption process and adsorption column filling is as follows:

[0031] The adsorption column is 300 mm high and has an inner diameter of 12.7 mm. After multiple rounds of experimental analysis, the adsorption capacity of 13X for 2-chloropropane is about 80-100 mg / g, and the adsorption capacity of ZSM-5 for isopentane is about 70-90 mg / g. In order to ensure that 13X can completely remove 2-chloropropane and does not affect the subsequent absorption of isopentane by ZSM-5 (excess 2-chloropropane will compete with isopentane, reduce the adsorption capacity of ZSM-5 for isopentane, and increase the burden of ZSM-5), the ratio of 13X to ZSM-5 is selected to be approximately the ratio of 2-chloropropane to isopentane in the adsorption raw material. That is, the A filler is 13X molecular sieve with a particle size of 1 to 3 mm and a filling of 3 to 7 g; the B filler is ZSM-5 molecular sieve with a particle size of 1 to 3 mm and a filling of 13 to 17 g; the crude product is the product (liquid phase) extracted after simple distillation and is sampled as a raw material for the adsorption section: the content ratio of each component in the crude product is approximately tetramethylsilane (TMS) (77 to 87%), isopentane (8 to 15%), 2-chloropropane (2 to 8%) and the remainder is other impurities; the 4N product is a product with a tetramethylsilane (TMS) component content of more than 99.99%.

[0032] Example 1

[0033] In the present embodiment, the content ratio of each component in the crude product is about tetramethylsilane (TMS) (80%), isopentane (14.5%), 2-chloropropane (4.6%) and other impurities of the surplus, which are continuously fed as the raw material liquid phase of the adsorption unit in the adsorption unit. The molecular sieve ratio of the adsorption column is calculated according to the ratio of 2-chloropropane and isopentane in the adsorption raw material, 13X (A) is filled with 5g, ZSM-5 (B) is filled with 15g, and the feed flow rate is 3mL / h. The adsorption column is injected into the adsorption column through a vaporizer, and the vaporization temperature is 35°C. The adsorption column is set at a temperature of 35°C. The gas phase tetramethylsilane (TMS) at the upper end of the adsorption column obtains 6.05g of liquid phase 4N product through a condenser, and the raw material consumption is 8.31g, and ZSM-5 absorbs 1.10g of isopentane, and 13X absorbs 0.35g of 2-chloropropane, and the yield of tetramethylsilane is 91%.

[0034] Example 2

[0035] In the present embodiment, the content ratio of each component in the crude product is about tetramethylsilane (TMS) (87%), isopentane (10.6%), 2-chloropropane (2.2%) and other impurities of the surplus, which are continuously fed as the raw material liquid phase of the adsorption unit in the adsorption unit. The molecular sieve ratio of the adsorption column is calculated according to the ratio of 2-chloropropane and isopentane in the adsorption raw material, 13X (A) is filled with 3g, ZSM-5 (B) is filled with 17g, and the feed flow rate is 3mL / h. The adsorption column is injected into the adsorption column through a vaporizer, and the vaporization temperature is 35°C. The adsorption column is set at a temperature of 35°C. The gas phase tetramethylsilane (TMS) at the upper end of the adsorption column obtains 10.4g of liquid phase 4N product through a condenser, and the raw material consumption is 12.86g, and ZSM-5 absorbs 1.27g of isopentane, and 13X absorbs 0.26g of 2-chloropropane, and the yield of tetramethylsilane is 93%.

[0036] Example 3

[0037] The difference between this embodiment and embodiment 2 is that the adsorption temperature is 40°C. In this embodiment, the content ratio of each component in the crude product is about tetramethylsilane (TMS) (87%), isopentane (10.6%), 2-chloropropane (2.2%) and other impurities of the remainder, which are continuously fed in the adsorption unit as the raw material liquid phase of the adsorption unit. The molecular sieve ratio of the adsorption column is calculated according to the ratio of 2-chloropropane and isopentane in the adsorption raw material, 13X (A) is filled with 3g, ZSM-5 (B) is filled with 17g, the raw material is liquid phase, the feed flow rate is 3mL / h, and the adsorption column is injected into the adsorption column through a vaporizer, the vaporization temperature is 35°C, the adsorption column is set at a temperature of 40°C, and the gas phase tetramethylsilane (TMS) at the upper end of the adsorption column is obtained through a condenser to obtain a liquid phase 4N product 9.82g, the raw material consumption is 12.40g, ZSM-5 adsorbs 1.20g of isopentane, 13X adsorbs 0.25g of 2-chloropropane, and the yield of tetramethylsilane is 91%.

[0038] Example 4

[0039] The difference between this embodiment and embodiment 2 is that the adsorption temperature is 30°C. In this embodiment, the content ratio of each component in the crude product is about tetramethylsilane (TMS) (87%), isopentane (10.6%), 2-chloropropane (2.2%) and other impurities of the remainder, which are continuously fed in the adsorption unit as the raw material liquid phase of the adsorption unit. The molecular sieve ratio of the adsorption column is calculated according to the ratio of 2-chloropropane and isopentane in the adsorption raw material, 13X (A) is filled with 3g, ZSM-5 (B) is filled with 17g, the raw material is liquid phase, the feed flow rate is 3mL / h, and the adsorption column is injected into the adsorption column through a vaporizer, the vaporization temperature is 35°C, the adsorption column is set at a temperature of 30°C, and the gas phase tetramethylsilane (TMS) at the upper end of the adsorption column is obtained through a condenser to obtain 11.1g of liquid phase 4N product, the raw material consumption is 13.78g, ZSM-5 adsorbs 1.35g of isopentane, 13X adsorbs 0.28g of 2-chloropropane, and the yield of tetramethylsilane is 93%.

[0040] Comparative Example 1

[0041] The difference between this comparative example and Example 2 is that the molecular sieve is filled with 13X. In this example, the content ratio of each component in the crude product is about tetramethylsilane (TMS) (84.6%), isopentane (9.6%), 2-chloropropane (5.5%) and other impurities of the remainder, which are continuously fed in the adsorption unit as the adsorption unit raw material liquid phase. The molecular sieve filled in the adsorption column is filled with 13X, that is, 13X (A) is filled with 15g, ZSM-5 (B) is filled with 0g, the feed flow rate is 3mL / h, and the adsorption column is injected into the adsorption column through a vaporizer, the vaporization temperature is 35°C, the adsorption column is set at a temperature of 35°C, and the gas phase tetramethylsilane (TMS) at the upper end of the adsorption column is obtained through a condenser to obtain 0.6g of liquid phase 4N product, the raw material consumption is 1.50g, 13X adsorbs 0.22g of isopentane and 0.08g of 2-chloropropane, and the yield of tetramethylsilane is 47%.

[0042] Comparative Example 2

[0043] The difference between this comparative example and Example 2 is that the molecular sieve is fully loaded with ZSM-5. In this example, the content ratio of each component in the crude product is about tetramethylsilane (TMS) (84.6%), isopentane (9.6%), 2-chloropropane (5.5%) and other impurities of the remainder, which are continuously fed as the raw liquid phase of the adsorption unit in the adsorption unit. The molecular sieve loaded in the adsorption column is fully loaded with ZSM-5, that is, 13X (A) is loaded with 0g, and ZSM-5 (B) is loaded with 15g, and the feed flow rate is 3mL / h. It is injected into the adsorption column through a vaporizer, the vaporization temperature is 35°C, and the adsorption column is set at a temperature of 35°C. The gaseous tetramethylsilane (TMS) at the upper end of the adsorption column is obtained through a condenser to obtain 5.5g of liquid phase 4N product, and the raw material consumption is 7.6g. ZSM-5 adsorbs 0.73g of isopentane and 0.42g of 2-chloropropane, and the yield of tetramethylsilane is 86%.

[0044] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0045] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for separating electronic grade tetramethylsilane from low boiling point organic silicon products, comprising: Obtaining a crude product of raw gas after light and heavy removal; The raw gas crude product is sequentially adsorbed and purified by a polar adsorption part and a volume adsorption part, wherein the polar adsorption part at least includes a polar adsorbent, and the volume adsorption part at least includes a porous adsorbent. The polar adsorbent is selected to have selective polar adsorption for 2-chloropropane, and the porous adsorbent is selected to have selective volume adsorption for isopentane.

2. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 1, characterized in that: The raw gas crude product comprises v / v%: 77-87% tetramethylsilane, 8-15% isopentane, 2-8% 2-chloropropane and the remainder of other impurities.

3. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 1, characterized in that: The polar adsorbent is selected from zeolite molecular sieve and 13X molecular sieve.

4. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 3, characterized in that: The polar adsorbent is 13X molecular sieve.

5. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 1, characterized in that: The porous adsorbent is selected from ZSM-5 zeolite molecular sieve and 5A molecular sieve.

6. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 5, characterized in that: The porous adsorbent is ZSM-5 zeolite molecular sieve.

7. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 1, characterized in that: The polar adsorption part and the volume adsorption part are different molecular sieve filling parts arranged in the same adsorption column, and the filling amount ratio of the polar adsorption part and the volume adsorption part meets the composition ratio of tetramethylsilane and target impurities in the raw gas crude product.

8. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 1, characterized in that: The conditions for the adsorption purification are: temperature 30-40° C., and pressure ranging from slightly negative pressure to slightly positive pressure.

9. The method for separating electronic grade tetramethylsilane from low boiling point organic silicon products according to claim 8, characterized in that: The pressure is 0.06-0.15 MPaG.

10. Use of the method for separating electronic-grade tetramethylsilane from low-boiling-point organic silicon products according to any one of claims 1 to 9 in the preparation of electronic-grade tetramethylsilane.

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