PROCESS FOR REMOVAL OF BROMINE, IODINE, BROMINE- AND/OR IODINE-CONTAINING COMPOUNDS FROM CHLOROSILANES

1 . A process for removal of bromine- or iodine-containing silicon compounds of general formula III

SiHal 4-n H n   (Ill)

from compositions of chlorosilanes, wherein the chlorosilanes comprise

at least one chlorosilane of general formula I

SiCl 4   (I),

polyperchlorosilanes of general formula II

wherein R 1 is in each case chlorine and wherein m =0 to 100, and

branched polyperchlorosilanes and/or cyclic polyperchlorosilanes and/or mixtures thereof,

the process comprising:

(i) converting the composition of chlorosilanes into the gaseous state;

(ii) subjecting to a nonthermal plasma to obtain a converted composition of chlorosilanes;

(iii) distilling the converted composition of chlorosilanes; and

(iv) obtaining a composition of chlorosilanes having a reduced content of bromine, bromine- and/or iodine-containing silicon compounds,

wherein

the silicon tetrachloride of general formula I and/or hexadichlorosilane of formula II where n=0 is subjected to a nonthermal plasma, and

the bromine- and/or iodine-containing silicon compounds are halosilanes of general formula III

SiHal 4-n H a   (III),

wherein at least one Hal is selected from bromine and iodine and further Hal is independently selected from iodine where n=0, 1, 2 or 3.

2 . The process according to claim 1 ,

wherein

the subjecting (ii) effects the nonthermal plasma treatment at a pressure of from 1 to 1000 mbar abs .

3 . The process according to claim 1 ,

wherein

the bromine- and/or iodine-containing silicon compounds are HSiCl 2 Br or HSiClBr 2 .

4 . The process according to claim 1 ,

wherein

subjecting (ii) and optionally distilling (iii) are effected continuously.

5 . The process according to claim 1 ,

wherein

the converted bromine- and/or iodine-containing silicon compounds in the distilling (iii) accumulate in a collection vessel of an apparatus for performing the process.

6 . The process according to claim 1 ,

wherein

in (iii) the distillative workup is effected at a pressure between 1 to 1500 mbar abs .

7 . The process according to claim 1 ,

wherein

in (iii) the distillative workup of the converted composition is effected at tops temperatures in the range from 40° C. to 250° C.

8 . The process according to claim 1 ,

wherein the plasma is a nonthermal plasma.

9 . The process according to claim 1 ,

wherein

the composition in (iv) comprises not more than 1 ppmw of bromine and/or iodine.

10 . The process according to claim 1 ,

wherein

nonthermal plasma is generated in a tubular reactor.

11 . The process according to claim 8 ,

wherein

the plasma has a power density of 1 to 20 W/cm 3 .

12 . The process according to claim 10 ,

wherein

nonthermal plasma is generated in a glass tubular reactor.

13 . The process according to claim 10 ,

wherein

nonthermal plasma is generated in a fused quartz tubular reactor.