METHOD FOR PRODUCING CHLOROSILANES

Abstract

The present disclosure relates to a process for producing chlorosilanes by reaction of a reaction gas containing hydrogen, tetrachlorosilane and optionally at least one further chlorosilane in a reactor and optionally in the presence of a catalyst. The chlorosilanes have the general formula H.sub.nSiCl.sub.4-n, and the reactor design is described by an index K1, the composition of the reaction gas before entry into the reactor is described by an index K2, and the reaction conditions are described by an index K3.

Claims

1-18. (canceled)

19. A process for producing chlorosilanes, comprising: reacting a reaction gas containing hydrogen, tetrachlorosilane and optionally at least one further chlorosilane in a reactor, optionally in the presence of a catalyst, wherein the chlorosilanes have the general formula H.sub.nSiCl.sub.4-n where n=1 to 3, and wherein the reactor design is described by an index $K1=\kappa .Math.\vartheta .Math.\frac{\left(A_{\mathrm{tot},\Delta T-}-A_{\mathrm{tot},\Delta T+}\right).Math.l_{\mathrm{tot},\mathrm{gas}}}{V_{R,\mathrm{eff}}};$ wherein ∂ is a $\mathrm{temperature}\mathrm{factor}=\frac{T_{\mathrm{gas},\mathrm{out}}-T_{\mathrm{gas},\mathrm{in}}}{T_{\mathrm{gas},\mathrm{control}}};$ wherein T.sub.gas,out is a gas outlet temperature [° C.]; wherein T.sub.gas,in is a gas inlet temperature [° C.]; and wherein T.sub.gas,control is a control temperature [° C.]; wherein x is an $\mathrm{area}\mathrm{factor}=\frac{A_{\mathrm{active}}+A_{\mathrm{cat}}}{A_{\mathrm{passive}}};$ wherein A.sub.active is a surface area having an effect on byproduct formation [m.sup.2]; wherein A.sub.cat is a surface area having a catalytic effect on byproducts [m.sup.2]; wherein A.sub.passive is a surface area without effect on byproduct formation [m.sup.2]; wherein A.sub.tot,ΔT− is a cooled heat exchanger surface area in the reactor [m.sup.2]; wherein A.sub.tot,ΔT+ is a heated heat exchanger surface area in the reactor [m.sup.2]; wherein V.sub.R,eff is an effective reactor volume [m.sup.3]; wherein l.sub.tot,gas is a length of gas path in reactor [m]; wherein A.sub.tot,ΔT− is 320 to 1450 m.sup.2; wherein A.sub.tot,ΔT+ is 90 to 420 m.sup.2; wherein V.sub.R,eff is 2 to 15 m.sup.3; and wherein l.sub.tot,gas is 5 to 70 m; wherein the composition of the reaction gas before entry into the reactor is described by an index $K2=R_{\mathrm{tot},\mathrm{gas}}.Math.\frac{{\stackrel{.}{V}}_{n,\mathrm{STC}}}{{\stackrel{.}{V}}_{n,H2}}.Math.100;$ wherein {dot over (V)}.sub.n,STC is a volume flow of STC [Nm.sup.3/h]; wherein {dot over (V)}.sub.n,H2 is a volume flow of hydrogen [Nm.sup.3/h]; wherein R.sub.tot,gas is a purity of the reaction gas [%]; wherein {dot over (V)}.sub.n,STC is 600 to 5800 Nm.sup.3/h; and wherein {dot over (V)}.sub.n,H2 is 750 to 13,500 Nm.sup.3/h; the reaction conditions are described by an index $K3=W_{\mathrm{el}}.Math.\frac{v_F}{V_{R,\mathrm{eff}}}.Math.\frac{{\rho }_F}{p_{\mathrm{diff}}^2}.Math.{10}^{10};$ wherein W.sub.el is an electrical power [kg*m.sup.2/s.sup.2]; wherein ν.sub.F is a kinematic viscosity of the fluid [m.sup.2/s]; wherein ρ.sub.F is a fluid density [kg/m.sup.3]; wherein p.sub.diff is a differential pressure of reaction gas [kg/m*s.sup.2]; wherein W.sub.el is 450,000 to 3,700,000 kg*m.sup.2/s.sup.2; wherein ν.sub.F is 2.5*10.sup.−4 to 5.1*10.sup.−4 m.sup.2/s; wherein ρ.sub.F is 19.5 to 28 kg/m.sup.3; and wherein p.sub.diff is 4.5*10.sup.5 to 3*10.sup.6 kg/m*s.sup.2; and wherein K1 has a value of 66 to 2300, K2 has a value of 13 to 250 and K3 has a value of 7 to 1470.

20. The process of claim 19, wherein K1 has a value of 95 to 1375 or preferably of 640 to 780.

21. The process of claim 19, wherein K2 has a value of 20 to 189 or preferably of 45 to 85.

22. The process of claim 19, wherein K3 has a value of 24 to 866 or preferably of 40 to 300.

23. The process of claim 19, wherein the effective reactor volume V.sub.R,eff is 4 to 9 m.sup.3.

24. The process of claim 19, wherein the heated heat exchanger surface area in the reactor A.sub.tot,ΔT+ is 120 to 360 m.sup.2.

25. The process of claim 19, wherein the cooled heat exchanger surface area in the reactor A.sub.tot,ΔT− is 450 to 1320 m.sup.2.

26. The process of claim 19, wherein the length of the gas path in the reactor l.sub.tot,gas is 25 to 37 m.

27. The process of claim 19, wherein the catalyst is in the form of a coating on a surface area in the reactor interior.

28. The process of claim 19, wherein the volume flow of the silicon tetrachloride {dot over (V)}.sub.n,STC is 1,100 to 4,500 Nm.sup.3/h.

29. The process of claim 19, wherein the volume flow of the hydrogen {dot over (V)}.sub.n,H2 is 1,350 to 9,000 Nm.sup.3/h.

30. The process of claim 19, wherein the reaction gas has a content of silicon tetrachloride, hydrogen and any further chlorosilane present of at least 97%, preferably at least 98%, or particularly preferably at least 99%.

31. The process of claim 19, wherein the further chlorosilane is disilane of the general formula H.sub.mCl.sub.6-mSi.sub.2 (m=0 to 5) and/or dichlorosilane.

32. The process of claim 19, wherein the kinematic viscosity ν.sub.F is 2.8*10.sup.−4 to 4.7*10.sup.−4 m.sup.2/s.

33. The process of claim 19, wherein the fluid density ρ.sub.F is 21.5 to 26 kg/m.sup.3.

34. The process of claim 19, wherein the electrical energy W.sub.el is 500,000 to 3,200,000 kg*m.sup.2/s.sup.2.

35. The process of claim 19, wherein the differential pressure of the reaction gas p.sub.diff is 6*10.sup.5 to 2.6*10.sup.6 kg/m*s.sup.2.

Description

EXAMPLES

[0067] In order to apply the findings and correlations to productivity in the production of chlorosilanes and to define the ranges for the indices K1, K2 and K3 (operating ranges) detailed investigations on continuously operated high temperature converters of different sizes were performed.

[0068] Various experiments V were performed (table 1: V1 to V13) and the parameters underlying the indices were varied in turn to define a general, optimal operating range for the HTC. The selected parameter combinations of K1, K2 and K3 were evaluated and the optimal range defined based on conversion [kg/(Nm.sup.3)], i.e. the amount of TCS [kg] produced per hour based on the amount of STC [Nm.sup.3] used in the reactor. A conversion of 15.3 kg/Nm.sup.3 is considered normal to good productivity. At a conversion above this value productivity is considered optimal. Conversion is therefore normalized by a factor of 15.3 kg/Nm.sup.3 to indicate productivity. An optimal productivity is accordingly above 100%. V1 to V13 are shown as representatives of a multiplicity of experiments performed for determination of optimal ranges.

TABLE-US-00002 TABLE 1 Productivity [%] K1 K2 K3 V1 98.9 25 11 13 V2 102.2 640 52 120 V3 101.4 900 130 85 V4 100.1 350 32 85 V5 102.5 730 60 145 V6 94.2 3000 284 3 V7 98.5 50 18 85 V8 97.4 10 420 600 V9 100.4 650 53 60 V10 101.8 750 80 290 V11 99.7 750 13 1490 V12 96.9 2505 40 800 V13 96.2 600 80 5

[0069] The experiments verify that an elevated/optimal chlorosilane production can be accomplished by HTC provided that the process is kept in the claimed ranges of the indices K1, K2 and K3.