PROCESS FOR REMOVING AN IMPURITY FROM A CHLOROSILANE MIXTURE

Abstract

A process for removing an impurity from a mixture containing at least one chlorosilane and/or organochlorosilane and at least one impurity from the group comprising a boron compound, a phosphorus compound, and an arsenic compound is provided. The process includes contacting the liquid mixture with an unfunctionalized organic polymer having pores with an average pore diameter of less than 50 Å, the average pore diameter being determined in accordance with DIN ISO 66134, and optionally removing the unfunctionalized organic polymer.

Claims

1-15. (canceled)

16. A process for removing an impurity from a mixture containing at least one chlorosilane and/or organochlorosilane and at least one impurity from the group comprising boron compound, phosphorus compound, and arsenic compound, said process comprising the steps of: a) contacting the liquid mixture with an unfunctionalized organic polymer having pores with an average pore diameter of less than 50 Å, the average pore diameter being determined in accordance with DIN ISO 66134; b) optionally removing the unfunctionalized organic polymer.

17. The process as claimed in claim 16, wherein the average pore diameter is 15 to 48 Å.

18. The process as claimed in claim 16, wherein the unfunctionalized organic polymer has a pore count maximum at a pore diameter of <100 Å.

19. The process as claimed in claim 16, wherein the unfunctionalized organic polymer has a specific surface area of 25 to 1050 m.sup.2/g.

20. The process as claimed in claim 16, wherein the unfunctionalized organic polymer has a specific surface area of >1050 m.sup.2/g, with the proviso that a value of 2500 m.sup.2/g is not exceeded.

21. The process as claimed in claim 16, wherein the chlorosilane is an acyclic chlorosilane of the general formula H.sub.xSi.sub.nCl.sub.(2n+2−x), where 0≤x≥12 and 1≤n>5, and/or a cyclic chlorosilane of the general formula H.sub.xSi.sub.nCl.sub.(2n-x), where 0≤x≥20 and 5≤n≥10.

22. The process as claimed in claim 16, wherein the chlorosilane is selected from the group comprising silicon tetrachloride, trichlorosilane, dichlorosilane, monochlorosilane, and combinations thereof.

23. The process as claimed in claim 16, wherein the organochlorosilane is an acyclic organochlorosilane of the general formula H.sub.xSi.sub.nR.sup.3.sub.yCl.sub.(2n+2−x−y), where 0≤x≥11, 1≤n≥5, and 1≤y≥12, and/or a cyclic organochlorosilane of the general formula H.sub.xSi.sub.nR.sup.3.sub.yCl.sub.(2n−x−y), where 0≤x>19, 5≤n≥10, and 1≤y≥20 and where R.sup.3=alkyl, aryl, alkylaryl or alkoxy.

24. The process as claimed in claim 16, wherein the unfunctionalized organic polymer contains a proportion of water of less than 5% by weight.

25. The process as claimed in claim 16, wherein the unfunctionalized organic polymer is selected from the group comprising polyethylene, polystyrene, polydivinylbenzene, styrene-divinylbenzene copolymer, and combinations thereof.

26. The process as claimed in claim 25, wherein the unfunctionalized organic polymer comprises a styrene-divinylbenzene copolymer.

27. The process as claimed in claim 16, wherein the unfunctionalized organic polymer comprises a hypercrosslinked polymer.

28. The process as claimed in claim 16, wherein the unfunctionalized organic polymer in particulate form has an average particle size of 0.149 to 4.760 mm.

29. The process as claimed in claim 16, wherein in step a) the unfunctionalized organic polymer is in the form of a fixed bed in one or more containers arranged in series or in parallel, through which the mixture passes in a continuous stream.

30. The process as claimed in claim 29, wherein the hydrodynamic residence time of the mixture in the reaction volume is 0.1 to 100 000 s.

Description

EXAMPLES

Example 1: General Procedure

[0074] 20 g of a chlorosilane mixture (>99.9% TCS) was added to 0.68 g of the unfunctionalized polymer in a glass flask at 22° C. and 1 bar (a). The polymer was subsequently removed by filtration and the ratio of the chlorosilanes in the mixture obtained was analyzed by gas chromatography with a thermal conductivity detector (GC-TCD). The boron concentration was determined by ICP-OES before and after the contacting.

Example 1

[0075] A styrene polymer (hypercrosslinked) having an average pore diameter of 46 Å and a specific surface area of 1138 m.sup.2/g and with high physical stability (crush strength>500 g/beads) was used.

TABLE-US-00001 TABLE 1 Before contacting the After contacting the mixture with the polymer mixture with the polymer Boron [ppbw] 7000 270

[0076] A boron retention of 96% is achieved.

TABLE-US-00002 TABLE 2 Component before step a) after step b) Monochlorosilane/wt. % 0.0000 0.0819 DCS/wt. % 0.0010 5.7989 TCS/wt. % 99.9757 82.3719 STC/wt. % 0.0233 11.7473

[0077] >17.5% by weight of disproportionation products was formed (sum of monochlorosilane, DCS, STC).

Example 2

[0078] A styrene polymer having an average pore diameter of 45 Å and a specific surface area of 937 m.sup.2/g was used. The pore count maximum was at a pore diameter of 81 Å (pore diameter distribution in accordance with DIN 66134).

TABLE-US-00003 TABLE 3 Before contacting the After contacting the mixture with the polymer mixture with the polymer Boron [ppbw] 13000 1500

[0079] A boron retention of 88% is achieved.

TABLE-US-00004 TABLE 4 Component before step a) after step b) Monochlorosilane/wt. % 0.0000 0.0000 DCS/wt. % 0.0003 0.0009 TCS/wt. % 99.9967 99.9891 STC/wt. % 0.0030 0.0100

[0080] Less than 0.1% by weight of disproportionation products was formed (sum of monochlorosilane, DCS, STC).

Example 3

[0081] A styrene polymer having an average pore diameter of 48 Å and a specific surface area of 554 m.sup.2/g was used. The pore count maximum was at a pore diameter of 58 Å (pore diameter distribution in accordance with DIN 66134).

TABLE-US-00005 TABLE 5 Before contacting After contacting with the polymer with the polymer Boron [ppbw] 6200 250

[0082] A boron retention of 96% is achieved.

TABLE-US-00006 TABLE 6 Component before step a) after step b) Monochlorosilane/wt. % 0.0000 0.0000 DCS/wt. % 0.0003 0.0011 TCS/wt. % 99.9967 99.3209 STC/wt. % 0.0030 0.6780

[0083] <0.7% by weight of disproportionation products was formed (sum of monochlorosilane, DCS, STC).

Comparative Example 3

[0084] A styrene-DVB polymer having an average pore diameter of 50 Å and a specific surface area of 862 m.sup.2/g was used. The maximum in the pore diameter distribution in accordance with DIN 66134) was at 100 Å.

TABLE-US-00007 TABLE 7 Before contacting After contacting with the polymer with the polymer Boron [ppbw] 7000 1100

[0085] A boron retention of only 84% is achieved.

TABLE-US-00008 TABLE 8 Component before step a) after step b) Monochlorosilane/wt. % 0.0000 0.0136 DCS/wt. % 0.0003 0.0032 TCS/wt. % 99.9993 99.7878 STC/wt. % 0.0004 0.1954

[0086] <0.25% by weight of disproportionation products was formed (sum of monochlorosilane, DCS, STC).

Comparative Example 4

[0087] A crosslinked styrene-DVB polymer (Amberlite XAD-1180) having an average pore diameter of 300 Å and a specific surface area of >600 m.sup.2/g was used.

TABLE-US-00009 TABLE 9 Before contacting After contacting with the polymer with the polymer Boron [ppbw] 11000 4300

[0088] A boron retention of only 61% is achieved.

TABLE-US-00010 TABLE 10 Component before step a) after step b) Monochlorosilane/wt. % 0.0000 0.0000 DCS/wt. % 0.0000 0.0005 TCS/wt. % 99.9999 99.9722 STC/wt. % 0.0000 0.0273

[0089] <0.1% by weight of disproportionation products was formed (sum of monochlorosilane, DCS, STC).