METHOD FOR OBTAINING HEXACHLORODISILANE BY REACTING AT LEAST ONE PARTIALLY HYDROGENATED CHLORODISILANE ON A SOLID UNFUNCTIONALIZED ADSORBER

Abstract

A process for obtaining hexachlorodisilane and uses for the same. The process includes contacting at least one partially hydrogenated chlorodisilane of general formula H.sub.xSi.sub.2Cl.sub.(6-x) where x is from 1 to 5 in the liquid state with a solid non-functionalized adsorber material that is selected from the group comprising silicates, aluminosilicates, organic polymer and/or combinations thereof. The process also includes optionally separating the hexachlorodisilane and/or optionally separating the adsorber material.

Claims

1-15. (canceled)

16. A process for obtaining hexachlorodisilane, comprising: a) contacting at least one partially hydrogenated chlorodisilane of general formula H.sub.xSi.sub.2Cl.sub.(6-x) wherein x from 1 to 5 in the liquid state with a solid non-functionalized adsorber material selected from the group comprising silicates, aluminosilicates, organic polymer and combinations thereof; and b) optionally separating the hexachlorodisilane and/or optionally separating the adsorber material.

17. The process of claim 16, wherein the partially hydrogenated chlorodisilane is pentachlorodisilane.

18. The process of claim 16, wherein the organic polymer is selected from the group comprising polystyrene, polydivinylbenzene, styrene-divinylbenzene copolymer and combinations thereof.

19. The process of claim 16, wherein the non-functionalized adsorber material is a styrene-divinylbenzene copolymer.

20. The process of claim 16, wherein the non-functionalized adsorber material has an average particle size of 0.149 to 4.760 mm, preferably 0.177 to 2.0 mm, particularly preferably 0.210 to 1.410 mm.

21. The process of claim 16, wherein the non-functionalized adsorber material has a surface area of 200 to 2000 m.sup.2/g, preferably of 400 to 1000 m.sup.2/g, in particular of 500 to 850 m.sup.2/g.

22. The process of claim 16, wherein the non-functionalized adsorber material has an average pore diameter of 1 to 900*10.sup.−10 m, preferably of 2 to 450*10.sup.−10 m, particularly preferably of 4 to 200*10.sup.−10 m, in particular of 5 to 125*10.sup.−10 m.

23. The process of claim 16, wherein prior to the contacting the non-functionalized adsorber material contains a proportion of water of less than 5% by weight, preferably less than 3% by weight, particularly preferably less than 2% by weight.

24. The process of claim 16, wherein the at least one partially hydrogenated chlorodisilane is a constituent of a mixture containing at least one chlorosilane of general formula H.sub.(4-x)SiCl.sub.x wherein x is from 1 to 4.

25. The process of claim 24, wherein the mixture is an offgas stream from the production of polycrystalline silicon by hydrogen reduction of chlorosilane.

26. The process of claim 24, wherein the mixture is an offgas stream from the production of tetrachlorosilane by hydrogenation.

27. The process of claim 24, wherein low-boiling chlorosilanes present in the mixture are separated before the contacting with the non-functionalized adsorber material.

28. The process of claim 16, wherein after step a) the proportion of unconverted partially hydrogenated chlorodisilane is less than 10%, preferably less than 6%, particularly preferably less than 3%, based on the respective starting content of the chlorodisilane.

29. The process of claim 17, wherein the proportion of unconverted pentachlorodisilane is less than 5% by weight, preferably less than 2% by weight, particularly preferably 0.1% by weight, based on the starting content thereof.

30. The use of a solid non-functionalized adsorber material selected from the group comprising silicates, aluminosilicates, organic polymer and combinations thereof for obtaining hexachlorodisilane by contacting the adsorber material with at least one partially hydrogenated chlorodisilane of general formula H.sub.xSi.sub.2Cl.sub.(6-x) wherein x is from 1 to 5 in the liquid state.

Description

EXAMPLE 1

[0067] 3.75 g of a mixture containing chlorosilanes of general formula H.sub.(4-x)SiCl.sub.x where x=1 to 4, partially hydrogenated disilanes of general formula H.sub.xSi.sub.2Cl.sub.(6-x) where x=1 to 5 and HCDS were admixed with 0.15 g of the non-functionalized adsorber material. After a residence time of 24 h at 22° C. the adsorber material was separated by filtration and the obtained mixture analyzed by gas chromatography with a thermal conductivity detector (GC-TCD). The employed adsorber material was a styrene-divinylbenzene copolymer (for example Amberlite XAD-4). The particle size was 0.25-0.84 mm (20-60 mesh), the surface area was 750 m.sup.2/g and the non-functionalized adsorber material had an average pore diameter of 50*10.sup.−10 m.

TABLE-US-00001 TABLE 1 Component before step a) after step b) Dichlorosilane/% by 0.0000 0.0577 wt. Trichlorosilane/% by 0.0010 0.7589 wt. Tetrachlorosilane/% by 98.5769 98.1206 wt. Dichlorodisilane/% by 0.0248 0.0026 wt. Trichlorodisilane/% by 0.0223 0.0071 wt. Tetrachlorodisilane/% 0.2141 0.0247 by wt. Pentachlorodisilane/% 0.5874 0.0000 by wt. HCDS/% by wt. 0.5735 0.9673

[0068] As is apparent from table 1 an elevated proportion of HCDS was found after step b) (169% of the HCDS proportion in the employed mixture). The proportion of partially hydrogenated chlorodisilanes based on HCDS was reduced to 2.4% of the initial value (in the employed mixture). This example even achieved complete conversion of the pentachlorodisilane within the limits of detection.

EXAMPLE 2

[0069] 7.4 g of a mixture containing chlorosilanes of general formula H.sub.(4-x)SiCl.sub.x where x=1 to 4, partially hydrogenated disilanes of general formula H.sub.xSi.sub.2Cl.sub.(6-x) where x=1 to 5 and HCDS were admixed with 0.30 g of the non-functionalized adsorber material. After a residence time of 60 min at 22° C. the adsorber material was separated by filtration and the obtained mixture analyzed as in example 1. The adsorber material employed was that from example 1.

TABLE-US-00002 TABLE 2 Component before step a) after step b) Dichlorosilane/% by wt. 0.0000 0.0516 Trichlorosilane/% by wt. 0.0033 0.5532 Tetrachlorosilane/% by 98.6801 98.2499 wt. Dichlorodisilane/% by 0.0215 0.0033 wt. Trichlorodisilane/% by 0.0165 0.0008 wt. Tetrachlorodisilane/% 0.1837 0.0236 by wt. Pentachlorodisilane/% 0.5350 0.0305 by wt. HCDS/% by wt. 0.5599 1.0481

[0070] Even at a residence time of 60 min a markedly elevated proportion of HCDS was found, as is apparent from table 2 (187% of the HCDS proportion in the employed mixture). At this residence time the conversion of the partially hydrogenated chlorodisilanes is slightly lower. The proportion of partially hydrogenated chlorodisilanes based on HCDS was reduced to 4.1% of the initial value (in the employed mixture). A pentachlorodisilane conversion of 94.3% was achieved.

EXAMPLE 3

[0071] 3.75 g of a mixture containing chlorosilanes of general formula H.sub.(4-x)SiCl.sub.x where x=1 to 4, partially hydrogenated disilanes of general formula H.sub.xSi.sub.2Cl.sub.(6-x) where x=1 to 5 and HCDS were admixed with 0.15 g of the adsorber material. After a residence time of 27 h at 22° C. the adsorber material was separated by filtration and the obtained mixture analyzed as in example 1. The employed adsorber material was a styrene-divinylbenzene copolymer (for example Amberlite XAD-1180). The particle size was 0.25-0.84 mm (20-60 mesh), the surface area was 600 m.sup.2/g and the adsorber material had an average pore diameter of 300*10.sup.−10 m.

TABLE-US-00003 TABLE 3 Component before step a) after step b) Dichlorosilane/% by wt. 0.0000 0.0422 Trichlorosilane/% by wt. 0.0025 0.6958 Tetrachlorosilane/% by 98.7228 98.3846 wt. Dichlorodisilane/% by 0.0224 0.0031 wt. Trichlorodisilane/% by 0.0088 0.0066 wt. Tetrachlorodisilane/% 0.1711 0.0384 by wt. Pentachlorodisilane/% 0.5252 0.0004 by wt. HCDS/% by wt. 0.5472 0.7410

[0072] An elevated proportion of HCDS was found after step b) (table 3; 135% of the HCDS proportion in the employed mixture). The proportion of partially hydrogenated chlorodisilanes based on HCDS was reduced to 4.9% of the initial value (in the employed mixture). A pentachlorodisilane conversion of over 99.9% within the limits of detection was achieved.

COMPARATIVE EXAMPLE 4

[0073] The experimental setup was analogous to that of example 1 but an amino-functionalized polymer resin (Amberlyst 21 A) adsorber material according to WO 2016/091240 A1 was employed.

TABLE-US-00004 TABLE 4 Component before step a) after step b) Dichlorosilane/% by 0.0000 0.0120 wt. Trichlorosilane/% by 0.0025 0.9794 wt. Tetrachlorosilane/% by 98.7228 98.6081 wt. Dichlorodisilane/% by 0.0224 0.0000 wt. Trichlorodisilane/% by 0.0088 0.0000 wt. Tetrachlorodisilane/% 0.1711 0.0243 by wt. Pentachlorodisilane/% 0.5252 0.0015 by wt. HCDS/% by wt. 0.5472 0.2123

[0074] While the proportion of partially hydrogenated chlorodisilanes based on the HCDS was reduced to 9.2% of the initial value, this reduction was markedly smaller than that achieved with the process according to the invention (cf table 4). In addition, the proportion of HCDS in the mixture fell to 39% of the proportion in the employed mixture.

COMPARATIVE EXAMPLE 5

[0075] The experimental setup was analogous to that of example 3 but an N-functionalized polymer resin (Seplite LSC 794) adsorber material according to WO 2016/091240 A1 was employed.

TABLE-US-00005 TABLE 5 Component before step a) after step b) Dichlorosilane/% by wt. 0.0000 0.0021 Trichlorosilane/% by wt. 0.0025 0.0480 Tetrachlorosilane/% by 98.7228 98.9191 wt. Dichlorodisilane/% by 0.0224 0.0216 wt. Trichlorodisilane/% by 0.0088 0.0025 wt. Tetrachlorodisilane/% 0.1711 0.0932 by wt. Pentachlorodisilane/% 0.5252 0.3938 by wt. HCDS/% by wt. 0.5472 0.5123

[0076] An altogether low reactivity is apparent from table 5. A pentachlorodisilane conversion of only 25.0% was achieved. The HCDS yield was also reduced (94% of the HCDS proportion in the employed mixture).

COMPARATIVE EXAMPLE 6

[0077] The experimental setup was analogous to that of example 2 but an amino-functionalized polymer resin (Amberlyst 21 A) according to WO 2016/091240 A1 was employed as the adsorber material.

TABLE-US-00006 TABLE 6 Component before step a) after step b) Dichlorosilane/% by 0.0000 0.0198 wt. Trichlorosilane/% by 0.0033 0.6114 wt. Tetrachlorosilane/% by 98.6801 98.5583 wt. Dichlorodisilane/% by 0.0215 0.0046 wt. Trichlorodisilane/% by 0.0165 0.0022 wt. Tetrachlorodisilane/% 0.1837 0.0474 by wt. Pentachlorodisilane/% 0.5350 0.0902 by wt. HCDS/% by wt. 0.5599 0.6243

[0078] As shown in table 6 a slightly elevated proportion of HCDS was found at a residence time of 60 min (112% of the HCDS proportion in the employed mixture). At this residence time the conversion of the partially hydrogenated chlorodisilane is lower. The proportion of the partially hydrogenated chlorodisilanes based on HCDS was reduced to 17.1% of the initial value (in the employed mixture). A pentachlorodisilane conversion of 83.1% was achieved. It is clearly apparent that the comparative example only affords much lower yields of HCDS and at economically important short residence times the conversion of the partially hydrogenated disilanes is markedly lower than in the process according to the invention.