Systems and methods of producing trichlorosilane

Abstract

The present invention is directed to systems and methods of synthesizing trichlorosilane. The disclosed systems and methods can involve increasing the concentration of the solids in the slurry to recover or separate the volatilized metal salts and reduce the obstructions created by the solidification of the metal salts in downstream operations of the during trichlorosilane synthesis. Rather than heating to raise the temperature to vaporize chlorosilane compounds, and subsequently condensing the volatilized chlorosilane compounds, the present invention can involve increasing the solids concentration in the slurry stream by utilizing a non-condensable gas, such as hydrogen, to volatilize the chlorosilane components, which can consequently promote evaporative conditions that can reduce the slurry temperature. The lower slurry temperature results in a lower volatility of the metal salts, which reduces the likelihood of carryover to downstream unit operations.

1 . A method of preparing trichlorosilane comprising:
 introducing a reactant mixture into a reactor, the reactant mixture comprising silicon tetrachloride and hydrogen;   recovering a first crude product from the reactor, the first crude product comprising trichlorosilane, silicon tetrachloride, hydrogen, silicon, and metal salts;   separating at least a portion of the silicon and the metal salts from the first crude product to produce a second crude product and a first residue, the second crude product comprising trichlorosilane, silicon tetrachloride, and hydrogen, and the first residue comprising trichlorosilane, silicon tetrachloride, silicon, and metal salts; and   contacting at least a portion of the first residue with a contact gas to produce a solids-rich residue and a vapor product, the vapor product comprising trichlorosilane and silicon tetrachloride, and the solids-rich residue comprising silicon and metal salts.   
     
     
         2 . The method of  claim 1 , wherein the contact gas comprises hydrogen. 
     
     
         3 . The method of  claim 2 , further comprising:
 condensing at least a portion of the second crude product to produce a crude condensate; and   contacting at least a portion of the crude condensate with the first crude product.   
     
     
         4 . The method of  claim 3 , further comprising contacting at least a portion of the crude condensate with at least a portion of the vapor product. 
     
     
         5 . The method of  claim 4 , further comprising contacting at least a portion of the first residue with the first crude product. 
     
     
         6 . The method of  claim 5 , further comprising:
 separating at least a portion of trichlorosilane from at least a portion of the second crude product;   recovering at least a portion of silicon tetrachloride from at least a portion of the second crude product;   recovering at least a portion of hydrogen from at least a portion of the second crude product; and   introducing at least a portion of the recovered hydrogen into the reactor.   
     
     
         7 . The method of  claim 6 , wherein the contact gas is at least partially comprised of the recovered hydrogen. 
     
     
         8 . The method of  claim 6 , wherein the reactant mixture is at least partially comprised of recovered hydrogen and recovered silicon tetrachloride. 
     
     
         9 . The method of  claim 4 , wherein separating the at least a portion of the silicon and the metal chloride salts from the first crude product comprises:
 introducing the first crude product into a quench column;   recovering the second crude product from the quench column; and   recovering the first residue from the quench column.   
     
     
         10 . The method of  claim 9 , wherein contacting the at least a portion of the first residue with the contact gas comprises:
 introducing the contact gas into a stripper column;   introducing the at least a portion of the first residue into the stripper column;   recovering the vapor product from the stripper column; and   recovering the solids-rich residue from the stripper column.   
     
     
         11 . The method of  claim 10 , wherein separating the at least a portion of the silicon and the metal salts from the first crude product comprises contacting the at least a portion of the first crude product with at least a portion of the vapor product from the stripper column. 
     
     
         12 . The method of  claim 11 , further comprising:
 separating at least a portion of the silicon tetrachloride from the second crude product to produce recovered silicon tetrachloride and a third crude product comprising trichlorosilane and dichlorosilane; and   introducing at least a portion of the recovered silicon tetrachloride into the reactor.   
     
     
         13 . The method of  claim 12 , further comprising:
 increasing a concentration of the recovered silicon tetrachloride to produce a concentrated STC product; and   introducing the concentrated STC product into the reactor.   
     
     
         14 . The method of  claim 13 , further comprising:
 recovering at least a portion of hydrogen in the second crude product; and   introducing the at least a portion of the recovered hydrogen into the reactor with the concentrated STC product.   
     
     
         15 . The method of  claim 14 , further comprising separating trichlorosilane from the third crude product to produce a trichlorosilane-rich product. 
     
     
         16 . The method of  claim 15 , further comprising heating at least a portion of the reactant mixture to be introduced into the reactor with at least a portion of the first crude product from the reactor. 
     
     
         17 . The method of  claim 1 , further comprising introducing metallurgical grade silicon having metallic species into the reactor. 
     
     
         18 - 24 . (canceled) 
     
     
         25 . A method of synthesizing trichlorosilane comprising:
 hydrogenating silicon tetrachloride in a fluidized bed reactor to produce trichlorosilane in a first crude product stream, the first crude product stream further comprising silicon tetrachloride, hydrogen, silicon, and at least one metal salt;   separating at least a portion of the silicon and the at least one metal salt from the first crude product stream in a first separation column to produce a first residue stream and a second crude product stream, the first residue stream further comprising trichlorosilane and silicon tetrachloride; and   vaporizing at least a portion of the trichlorosilane and at least a portion of the silicon tetrachloride from at least a portion of the first residue stream with a contact stream in a second column to produce a vapor product stream and a solids-rich slurry stream, the solids-rich slurry stream comprising at least one metal salt and silicon, and the vapor product stream comprising vaporized trichlorosilane and vaporized silicon tetrachloride.   
     
     
         26 . The method of  claim 25 , wherein vaporizing the at least a portion of the trichlorosilane and the at least a portion of the silicon tetrachloride from the at least a portion of the first residue stream with the contact stream comprises contacting the at least a portion of the first residue stream with the contact stream that comprises hydrogen. 
     
     
         27 . The method of  claim 26 , wherein separating the at least a portion of the silicon and the at least one metal salt from the first crude product stream comprises contacting the first crude product stream with at least a portion of the first residue stream. 
     
     
         28 . The method of  claim 27 , further comprising:
 condensing at least a portion of the second crude product stream to produce a crude condensate stream; and   contacting the first crude product stream with the crude condensate stream.   
     
     
         29 . The method of  claim 28 , further comprising recovering at least a portion of hydrogen from the second crude product stream, and wherein vaporizing the at least a portion of the trichlorosilane and the at least a portion of the silicon tetrachloride from the at least a portion of the first residue stream comprises vaporizing with at least a portion of the recovered hydrogen. 
     
     
         30 . The method of  claim 29 , wherein hydrogenating the silicon tetrachloride comprises hydrogenating silicon tetrachloride with at least a portion of the recovered hydrogen. 
     
     
         31 . The method of  claim 30 , further comprising recovering at least a portion of silicon tetrachloride from the second crude product stream, and wherein hydrogenating silicon tetrachloride comprises hydrogenating at least a portion of the recovered silicon tetrachloride with at least a portion of the recovered hydrogen. 
     
     
         32 . The method of  claim 25 , further comprising, prior to hydrogenating silicon tetrachloride, heating a reactant mixture of silicon tetrachloride and hydrogen with the first crude product stream. 
     
     
         33 . A method of preparing trichlorosilane comprising:
 providing a reactant mixture comprising silicon tetrachloride and hydrogen;   introducing the reactant mixture into a reactor having reaction conditions that hydrogenates at least a portion of the silicon tetrachloride into trichlorosilane;   recovering a crude product comprising silicon tetrachloride, hydrogen, trichlorosilane, and metal salts;   heating at least a portion of the reactant mixture with at least a portion of the crude product; and   separating trichlorosilane from at least a portion of the crude product to produce a trichlorosilane product.   
     
     
         34 . The method of  claim 33 , further comprising:
 separating the crude product into a residue and a crude vapor product;   recovering hydrogen from at least a portion of the crude vapor product;   contacting at least a portion of the residue with at least a portion of the recovered hydrogen to produce a vapor product and a solids-rich residue comprising a metal salt; and   contacting the crude product with the vapor product.