Process for preparing octachlorotrisilane and higher polychlorosilanes with utilization of hexachlorodisilane

Patent metadata

Field	Value
Publication number	US-10023470-B2
Application number	US-201615138044-A
Country	US
Kind code	B2
Filing date	Apr 25, 2016
Priority date	Apr 28, 2015
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A controlled preparation of octachlorotrisilane and higher polychlorosilane such as DCTS and DCPS from monomeric chlorosilane, proceeds by exposing the chlorosilane to a nonthermal plasma and recycling chlorosilane that has not been converted to octachlorotrisilane into the plasma.

First claim

The invention claimed is:

1. A process for preparing octachlorotrisilane, a higher polychlorosilane, or a mixture thereof, said process comprising:
a) forming a nonthermal plasma by excitation by an AC voltage of base frequency f g in a gas which is within a plasma reactor and which consists of SiCl 4 , HSiCl 3 , or a mixture thereof, and optionally at least one inert gas,
to obtain a resulting mixture comprising
hexachlorodisilane, ortachlorotrisitane, a higher polychlorosilane, SiCl 4 and HSiCl 3 , and
b) pumping the resulting mixture out of the plasma reactor into a cooler, which is a condenser with a vacuum vessel, and
cooling the resulting mixture down to a temperature of not more than 0° C., condensing out the components SiCl 4 , HSiCl 3 , hexachlorodisilane, octachlorotrisilane, the higher polychlorosilane or mixtures thereof in the cooler, and
c) conducting the components into an evaporator, evaporating the components in the evaporator and then
recycling at least a portion of the components into the nonthermal plasma of step a, and at the same time
d) collecting the non-recycled higher polychlorosilane and
at least a portion each of the hexachlorodisilane and octachlorotfisilane obtained in step b a collecting vessel, and
e) subjecting the bottoms mixture obtained in step d to a distillation, wherein hexachlorodisilane is drawn off and conducted into the nonthermal plasma of step a, and
f) collecting the mixture of octachlorotrisilane and higher polychlorosilane which remains after the distillation.

2. The process according to claim 1 , wherein the temperature in the gas is set within the range from −60° C. to 200′C.

3. The process according to claim 1 , wherein the temperatures set in the plasma reactor and in the evaporator in step c are the same.

4. The process according to claim 1 , wherein, in step a,
at least one electromagnetic pulse with repetition rate g injected into the plasma
has a voltage component having an edge slope in the rising edge of 10 V ns −1 to 1 kV ns −1 , and has a pulse width b of 500 ns to 100 μs.

5. The process according to claim 4 , wherein
the base frequency f g of the AC voltage is from 1 Hz to 100 MHz,
the repetition rate g is from 0.1 Hz to 50 MHz, and
the amplitude is from 1 to 15 kV pp .

6. The process according to claim 4 , wherein the electromagnetic pulse injected into the plasma is superimposed with at least one further electromagnetic pulse with the same repetition rate, and the two or at least two'pulses are in a duty ratio of 1 to 1000 relative to one another.

7. The process according to claim 4 , wherein at least one electromagnetic pulse is injected by a pulse ballast with current or voltage impression.

8. The process according to Claim 1 , wherein the pressure in the vacuum vessel in step b is set to at least one value in the range from 1 to 10,000 mbar abs .

9. The process according to Claim 1 , wherein the temperature in step b is in the range from −60° C.

10. The process according to claim 1 , wherein the at least one inert gas is present in the plasma reactor, and wherein the at least one inert gas is at least one gas selected from the group consisting of a noble gas, nitrogen, and mixtures thereof.

11. An apparatus for performance of the process according to claim 1 , the apparatus comprising:
the plasma reactor suitable for generating a nonthemial plasma,
the cooler which is the condenser with the vacuum vessel,
the evaporator,
the collecting vessel, and
a distillation column,
wherein
an inlet of the plasma reactor is connected to a recycle line for the SiCl 4 and HSiCl 3 components and a portion of the higher polychlorosilane, and to a recycle line for the hexachlorodisilane drawn off from the distillation column.

12. The process of claim 1 , wherein the mixture of actachlorotrisilane and the at least one higher polychlorosilane k substantially free of hydrogen atoms.

13. The process of claim 1 , wherein the octachlorotrisilane is substantially free of monomeric chlorosilanes.

14. ; The process of claim 1 , wherein the oetachlorotrisilane is substantially free of polymeric chlorosilanes containing hydrogen atoms.

Assignees

• Evonik Degussa Gmbh

Inventors

• Moussallem Imad
• Lang Juergen Erwin
• Rauleder Hartwig
• Trocha Martin
• Brausch Nicole

Classifications

• C01B33/107 Primary

  Halogenated silanes · CPC title

• C01B33/10773

  Halogenated silanes obtained by disproportionation and molecular rearrangement of halogenated silanes · CPC title

• H05H5/047

  Pulsed generators · CPC title

• B01J19/088

  giving rise to electric discharges (for heating purposes H05B7/00; for the production of ozone C01B13/11, H01T19/00) · CPC title

• H05H1/46

  using applied electromagnetic fields, e.g. high frequency or microwave energy (H05H1/26 takes precedence) · CPC title