Abstract: Silane is removed from the exhaust gas of silicon CVD reactors by injecting a stoichiometric excess of halogen to produce halosilanes which are hydrolyzed in water. The removal method permits the use of small individual reactors at each CVD reactor site and eliminates the collection and transport of hazardous gases to a central disposal site for destruction.

Abstract: Trichlorosilane for producing polycrystal silicon and tetrachlorosilane for producing trichlorosilane are storaged under hydrogen gas as a sealing gas. High-purity polycrystal silicon is provided.

Abstract: A process for the production of monosilanes from the high-boiling residue resulting from the reaction of hydrogen chloride with silicon metalloid in a process typically referred to as the "direct process." The process comprises contacting a high-boiling residue resulting from the reaction of hydrogen chloride and silicon metalloid, with hydrogen gas in the presence of a catalytic amount of aluminum trichloride effective in promoting conversion of the high-boiling residue to monosilanes. The present process results in conversion of the high-boiling residue to monosilanes. At least a portion of the aluminum trichloride catalyst required for conduct of the process may be formed in situ during conduct of the direct process and isolation of the high-boiling residue.

Abstract: Compounds containing a tetradecachlorocyclohexasilane dianion are prepared by contacting trichlorosilane with a reagent composition comprising a tertiary polyamine. The compound ?pedeta.SiH.sub.2 Cl.sup.+1 !.sub.2 ?Si.sub.6 Cl.sub.14.sup.-2 ! wherein pedeta is N,N,N',N",N"-pentaethyldiethylenetriamine is prepared by contacting trichlorosilane with pedeta. The compound ?Ph.sub.4 P.sup.+1 !.sub.2 ?Si.sub.6 Cl.sub.14.sup.-2 ! is prepared by contacting trichlorosilane with a mixture of N,N,N',N'-tetraethylethylenediamine and triphenylphosphonium chloride. The tetradecachlorocyclohexasilane dianion can be chemically reduced to cyclohexasilane, a compound useful in the deposition of amorphous silicon films. The tetradecachlorcyclohexasilane dianion can also be contacted with a Grignard reagent to form a dodecaorganocyclohexasilane.

Abstract: A process for producing trichlorosilane by reacting silicon with hydrogen chloride, which comprises bringing at least one silane compound selected from the group consisting of dichlorosilane, monochlorosilane and monosilane into contact with silicon during or prior to a reaction between silicon and hydrogen chloride to remove silicon oxide on the surface of silicon, thereby improving the reactivity of silicon with hydrogen chloride to produce silicon trichloride stably. Further, an alkali metal compound is co-present in the reaction between silicon and hydrogen chloride to suppress the production of silicon tetrachloride, thereby making it possible to produce trichlorosilane at a high selectivity.

Abstract: A method of producing trichlorosilane having a reduced content of dichlorosilane, which comprises reacting a mixture of dichlorosilane and trichlorosilane with hydrogen chloride in the presence of activated carbon as a catalyst at a temperature of 0.degree. C. or higher and lower than 75.degree. C. to selectively convert dichlorosilane into trichlorosilane.

Abstract: High purity silica is obtained by the reaction of impure by-product waste silica with hydrogen fluoride preferably in the presence of water or sulfuric acid, producing silicon tetrafluoride gas and a mother liquor. The silicon tetrafluoride is separated from the mother liquor, which retains the impurities originally contained within the impure silica. The silicon tetrafluoride gas is contacted with high-purity water, in a clean environment, to form a slurry of high purity silica and high-purity hydrofluosilicic acid (FSA). A portion of the silica is filtered from the slurry and washed producing a high purity silica product. The rest of the silica-FSA slurry is preferably reacted with ammonia to form a slurry of ammonium fluoride and silica. The silica is separated from the ammonium fluoride and preferably washed and calcined to remove any remaining ammonium fluoride, leaving additional high purity silica product.

Abstract: An (alkylhalo)silane is prepared by charging a reactor with a contact mass comprising metallic silicon powder and a copper catalyst and feeding a gas containing an alkyl halide into the reactor whereby the silane is formed by direct synthesis. The contact mass in the reactor during reaction consists of particles having a mean particle size of 5-150 .mu.m and containing 10-80% by weight of particles having a particle size of up to 30 .mu.m and 10-90% by weight of particles having a particle size of at least 90 .mu.m. The contact mass is well fluidized to ensure rapid and uniform reaction whereby the (alkylhalo)silane is prepared at high selectivity with a minimized elutriating loss of contact mass.

Abstract: A method for the purification of chlorosilanes used for the manufacture of electronic-grade silicon and more particularly to a method for removing trace contaminants of phosphorus. The method comprises contacting a mixture comprising a chlorosilane and a phosphorus contaminant with an absorbent comprising a copper or compound of copper supported on silica.

Abstract: Catalytic dehalogenation (or hydrodehalogenation) of halogen-containing compounds of elements of group IV of the periodic table in the presence of hydrogen is carried out using a finely-dispersed catalytically active material which comprises silicon and at least one transition metal, and which is characterized by high catalytic activity and stability. This process can be used, for example, for synthesizing compounds or alternatively for decomposing halogen-containing compounds, for instance in waste-water or waste-gas purification processes. It is also suitable for dehalogenation (hydrodehalogenation) of halogen-containing silane compounds, for instance of silicon tetrachloride or alkyl trichlorosilane compounds, and the original purity of the silanes used as starting materials is retained by the products. Tetrachlorosilane, for example, can be converted into trichlorosilane.

Abstract: Highly pure disilicon hexafluoride is synthesized by a process in which a suspension of a fluorination agent is made by dispersing this fluorination agent in an oxybenzene compound as a solvent and disilicon hexachloride is dripped in the suspension to be caused to react with the fluorination agent in nitrogen gas flows under atmospheric pressure, the oxybenzene being expressed by a following formula: ##STR1## (where each of R.sub.1 and R.sub.2 is an alkyl group alternatively having one or more substituents; carbon numbers summed up by R.sub.1 and R.sub.2 are equal to at least 2; and m.gtoreq.1 and n.gtoreq.0).

Abstract: An (alkylhalo)silane is prepared by using a fluidized bed reactor equipped with a feed line for reactant gas and a delivery line for product gas, charging the reactor with a contact mass comprising metallic silicon powder and a copper catalyst, and feeding a reactant gas containing an alkyl halide through the feed line into the reactor whereby the silane is formed by direct synthesis. A dust collector is connected to the delivery line for collecting the contact mass carried over with the product gas, which is fed back to the reactor. The feed of the reactant gas is controlled such that a linear velocity multiplied by a density may range from 0.2-2 kg/m.sup.2 .multidot.sec.

Abstract: A one-step process for the production of monosilanes from the high-boiling residue resulting from the reaction of organochlorides with silicon metalloid in a process typically referred to as the "direct process." The process comprises contacting a mixture comprising the high-boiling residue, an organotrichlorosilane, and hydrogen chloride with a catalytic amount of catalyst composition effective in promoting the formation of monosilanes from the high-boiling residue. A preferred catalyst composition comprises aluminum trichloride, at least a portion of which may be formed in situ during conduct of the direct process and isolation of the high-boiling residue. Typically, the monosilane product of the present process comprises almost exclusively methyltrichlorosilane and tetrachlorosilane.

Abstract: A method for the redistribution of trichlorosilane in the presence of N,N,N',N'-tetraethylethylenediamine (TEEDA) to form a complex comprising dichlorosilane and TEEDA. The dichlorosilane can be disassociated from the TEEDA by a means such as heating and then used in standard processes requiring dichlorosilane. Alternatively, the complex comprising the dichlorosilane and TEEDA can be used as a reactant for hydrosilation of .alpha.,.beta.-unsaturated olefinic nitriles or reacted with Grignard type reagents to make organosilanes.

Abstract: Hazardous and carcinogenic asbestos waste characterized by a crystalline fibrous structure is transformed into non-carcinogenic, relatively nonhazardous, and non-crystalline solid compounds and gaseous compounds which have commercial utilization. The asbestos waste is so transformed by the complete fluorination of the crystalline fibrous silicate mineral defining the asbestos.

Abstract: Silicon fines which have been recovered from an organochlorosilane reactor are treated with HCl or elemental chlorine at an elevated temperature to salvage chlorosilane and metal salt values. Passivation is also achieved.

Abstract: An improved process for contacting hydrogen gas and tetrachlorosilane in a reactor comprising a pressurizable shell having located therein a reaction vessel forming a substantially closed inner chamber for reacting the hydrogen gas with the tetrachlorosilane. The improvement comprises feeding to an outer chamber between the pressurizable shell and the reaction vessel a gas or gaseous mixture having a chlorine to silicon molar ratio greater than about 3.5. The improvement reduces the concentration of hydrogen and tetrachlorosilane in the outer chamber that results from leakage of these gases from the substantially closed inner chamber and the detrimental reactions associated with such leakage on structural elements and performance of the reactor.

Abstract: A process for recovering chlorine present in a gaseous vent stream. The process comprises contacting a gaseous vent gas comprising hydrogen chloride and a hydrosilane with a chlorination catalyst to form a more chlorinated silane. The chlorination of the hydrosilane captures the chlorine of the hydrogen chloride as a substituent of the resulting chlorosilane and provides for a readily condensable chlorosilane.

Abstract: A process is provided by the present invention for the preparation of a partially-substituted fluorosilane represented by the following formula: SiH.sub.n F.sub.4-n wherein n stands for an integer of 1 to 3. The process comprises converting a corresponding partially-substituted chlorosilane represented by the following formula: SiH.sub.n Cl.sub.4-n wherein n has the same meaning as defined above into the partially-substituted fluorosilane by halogen replacement while using a fluorinating agent. The fluorinating agent is zinc fluoride having a water content not higher than 0.2 wt. %. Preferably, the size of crystallites in the direction of a (110) plane of the zinc fluoride is at least 500 .ANG..

Abstract: A process for the hydrogenation of chlorosilanes. The process comprises contacting a chlorosilane with aluminum and a hydrogen source selected from a group consisting of hydrogen gas and gaseous hydrogen chloride in the presence of a catalyst. The catalyst is selected from a group consisting of copper and copper compounds, tin and tin compounds, zinc and zinc compounds, and mixtures thereof.

Abstract: A method for processing chlorosilane distillation residues by hydrolysis with steam, in which the hydrolysis is carried out at escalating temperatures from about 130.degree. C. to at least 170.degree. C.

Abstract: A process for hydrofluoric acid digestion of inorganic silica/alumina matrix material for the production of silicon tetrafluoride and aluminum fluoride comprises the initial step of reacting the matrix material with hydrofluoric acid, to form silicon tetrafluoride gas and a solution/slurry containing aluminum fluoride, undigested oxides, and additional soluble and insoluble fluoride materials. The silicon tetrafluoride gas is purified of contaminants by condensing out impurities in cold traps and reacted with aqueous sodium fluoride to form a solution/slurry of fluorosilicate salt which is delivered to a filter press to separate sodium fluorosilicate powder from the solution/slurry. The sodium fluorosilicate powder is dried and delivered to a kiln at a temperature of about 600.degree. C. to 650.degree. C. to form substantially pure silicon tetrafluoride gas and sodium fluoride powder for collection.

Abstract: The present invention relates to a method for the purification of tetrachlorosilane used for the manufacture of electronic grade silicon and, more particularly, to a method for removing trace impurities of phosphorus. The method involves contacting liquid tetrachlorosilane with activated charcoal. The process is effective in reducing the phosphorus levels in the tetrachlorosilane to the parts per trillion range. The process can be run as a continuous or batch process with easy separation of the activated charcoal. containing the phosphorus contaminate from the tetrachlorosilane.

Abstract: A simple but very effective and reliable method is proposed for the decolorizing purification of a halogenated silane compound, e.g., methyl trichlorosilane, colored by containing a very small amount of heavy metal impurities such as iron. The method comprises: contacting the halogenated silane compound with a small amount of a cationic surface active agent which is solid and insoluble in the silane such as a quaternary ammonium salt, e.g., trimethyl octadecyl ammonium chloride, for 2 to 240 minutes; and then separating the silane compound from the cationic surface active agent.

Abstract: The present invention is a process for the production of silanes from the contact of silicon metal or a silicon containing material with hydrogen chloride. The described process employs a metal or metal compound on a solid support as a catalyst which increases the production of tetrachlorosilane. The metal or metal compound is selected from a group consisting of palladium and palladium compounds, rhodium and rhodium compounds, platinum and platinum compounds, iridium and iridium compounds, tin and tin compounds, nickel and nickel compounds, and aluminum and aluminum compounds. The process is run at a temperature of about 250.degree. C. to 500.degree. C.

Abstract: The present invention is a process for the production of silanes from the contact of hydrogen chloride with silicon. The silicon may be in the form of silicon metal or a silicon containing material. The described process employs a catalyst which increases the yield of tetrachlorosilane. The catalyst is selected from a group consisting of tin and tin compounds, nickel and nickel compounds, arsenic and arsenic compounds, palladium and palladium compounds, and mixtures thereof. The process is run at a temperature of about 250.degree. C. to 500.degree. C.

Abstract: Residual silicone from direct process manufacture of chlorosilanes is stabilized for transportation and disposal by pelletizing finely divided particles of finely divided residual silicon powder contaminated with chlorine, hydrogen, and oxygen and highly reactive and exothermic upon exposure to moisture, and impregnating the pellets with an organic binder.

Abstract: The described invention is a process for preparing silanes from the reaction of solid silicon monoxide with aromatic halides. The solid silicon monoxide is reacted with the aromatic halide in the presence of a catalyst which can increase the conversion of silicon monoxide to silanes, and partially select for arylsilane products. The process may employ an activation step in which the solid silicon monoxide is activated by heating in an inert atmosphere. Activation of the solid silicon monoxide can increase silicon conversion and increase selectivity for arylsilane products.

Abstract: The present invention is a process for separating particulate silicon from a liquid by-product stream containing silanes. The liquid by-product stream comprising silanes and particulate silicon is atomized into a heated zone to effect vaporization of the liquid silanes, thus drying the particulate silicon. The dried particulate silicon is separated from the gaseous silanes by filtration or other suitable means. The separated solid and gaseous phases may be used as feed to the process generating the by-product stream or as a feed for other processes.

Abstract: A process for the deposition of pure semiconductor silicon by reductive chemical vapor decomposition of a precursor silane, the process comprising: (1) forming and depositing semiconductor silicon on a heated substrate; (2) separating a mixture enriched in lower-boiling silanes from the effluent gases from the decomposition/deposition reactor; (3) combining the mixture enriched in lower-boiling silanes with additional tetrachlorosilane, so that there is present in the combination less than about 1.0 mole hydrogen bonded to silicon per mole of total silicon; (4) passing the combination through a bed of a solid disproportionation catalyst to facilitate disproportionation of hydrogen-containing silanes and chlorine-containing silanes to produce a stream that is reduced in content of silane, chlorosilane, and dichlorosilane and increased in content of trichlorosilane; and (5) isolating and separating the trichlorosilane.

Abstract: A process for the dismutation of chlorosilanes is disclosed in which the latter are in the gas phase for 0.01-100 sec. at 55.degree.-100.degree. C. or in the liquid phase for 1-1000 sec. at 25.degree.-55.degree. C. conducted in the presence of a catalyst, which is either unformed or is present in the form of spherical pellets, and which consists of one of four different organopolysiloxane compounds, optionally cross-linked, which essentially carry an amino or ammonium group as a functional group.

Abstract: A scavenger composition having utility for removal of water and silicon mu-oxide impurities from chlorosilanes, such scavenger composition comprising:(a) a support; and(b) associated with the support, one or more compound(s) selected from the group consisting of compounds of the formula:R.sub.a-x MCl.sub.xwherein:M is a metal selected from the group consisting of the monovalent metals lithium, sodium, and potassium; the divalent metals magnesium, strontium, barium, and calcium; and the trivalent metal aluminum;R is alkyl;a is a number equal to the valency of metal M; andx is a number having a value of from 0 to a, inclusive; andwherein said compound(s) of the formula R.sub.a-x MCl.sub.x have been activated for impurity-removal service by a reaction scheme selected from those of the group consisting of:(i) reaction of such compound(s) with hydrogen chloride to form a first reaction product therefrom, followed by reaction of the first reaction product with a chlorosilane of the formula:SiH.sub.4-y Cl.sub.

Abstract: Residues which are obtained from the distillation of chlorosilanes prepared by reaction of raw silicon with chlorine or hydrogen chloride are processed by treatment in aqueous phase with an excess of at least 15% of calcium carbonate, and the liquid components are recycled into the process so that no liquid waste is formed.

Abstract: Silicon difluoride is produced by the reduction of silicon tetrafluoride in a plasma torch under argon atmosphere. Instead of the usual reducing agents finely divided silicon has now been used as a reducing agent.

Abstract: Disclosed is a method for the processing of the residues that occur in the production of chlorosilane. The processing is performed by the separation of the residual chlorosilanes, followed by hydrolysis of these residues with water vapor. The water vapor used has a temperature between 100.degree. and 300.degree. C. and additionally contains hydrogen chloride. The hydrolysis residues occurring in the present method have an extremely small chloride content and can be transported, if desired, directly to a dump. The hydrogen chloride that is released can be absorbed in water and removed as hydrochloric acid or can be desorbed for further technical use. Preferably it is reused for chlorosilane production.

Abstract: A method for increasing the trichlorosilane yield in the hydrochlorination of silicon in a fluidized bed involves chilling the gas mixture issuing from the fluidized bed in the shortest possible time immediately after leaving the fluidized bed to temperatures below 550.degree. C. When the temperature of the fluidized bed is below 550.degree. C., the gas mixture is chilled to temperature 100.degree. C. lower than the reaction temperature in the fluidized bed. The method makes it possible, at a reaction temperature of, for example, 800.degree. C. to increase the 16 to 20% trichlorosilane yields obtained formerly at this temperature to 55%, especially when gaseous silicon tetrachloride is also added to the fluidized bed.

Abstract: The present invention is processes for preparing silanes from the reaction of silicon monoxide with hydrogen halides. In a first embodiment of the instant invention, silicon monoxide is reacted with a hydrogen halide to produce silanes and halosilanes. In a second embodiment of the instant invention, the silicon monoxide is activated by heating in an inert atmosphere prior to contact with the hydrogen halide. In a third embodiment of the instant invention, a catalyst is employed which enhances conversion of silicon monoxide to silanes and modifies process selectivity for silane products. The catalyzed process can be run with activated or non-activated silicon monoxide.

Abstract: The present invention is a process for preparing silanes from the reaction of solid silicon monoxide with organic halides. The solid silicon monoxide is reacted with the organic halide in the presence of a catalyst which can increase the conversion of silicon monoxide to silanes and partially select for the type of silanes produced. The process may employ an activation step in which the solid silicon monoxide is activated by heating in an inert atmosphere. Activation of the silicon monoxide can increase silicon conversion and alter the type of silanes produced.

Abstract: Disclosed are a method and apparatus for the preparation of dichlorosilane by the disproportionation of trichlorosilane at standard pressure and temperatures up to the boiling point of the trichlorosilane in a reactor having a solid-bed catalyst while removing dichlorosilane with contents of trichlorosilane from the gas chamber of the reactor for separation in a distillation column and derivation of liquid reaction phase for the separation of tetrachlorosilane from trichlorosilane in a distillation column with recycling of trichlorosilane into the reactor. Preferably a common distillation column is provided for both separations.

Abstract: The present invention comprises a process for the removal of oxides of nitrogen and sulfur from a gas mixture containing those species by exposure of the gas mixture to ultraviolet radiation having a wavelength below 200 nanometers in absence of ammonia.

Abstract: The present application relates to a method for production of trichloromonosilane in a fluidized bed reactor by reaction of silicon powder and HCl at a temperature between 280.degree. and 300.degree. C. wherein silicon powder which has been produced by gas atomization of molten silicon is used. The gas atomized silicon powder has a preferred particle size between 1 and 1000 .mu.m.

Abstract: A process is described for increasing the percentage of silicon tetrachloride during the reaction of hydrogen chloride or a mixture of hydrogen chloride and chlorine with substances containing metallic silicon. In this process the chlorosilanes are exposed to a temperature ranging between 300.degree. C. and 1400.degree. C.

Abstract: A method is disclosed for separating gaseous silicon compounds from hydrogen and/or hydracids. Specifically, the method comprises the utilization of semi-permeable membranes for such gaseous separation. Particularly preferred is a composite membrane comprised of a coating separation layer of sulfonated polysulfone and a support layer of polysulfone. Mixtures of hydrogen and silane are particularly suitable for being separated by means of composite membrane separation.

Abstract: A continuous process is disclosed for the production, with a high yield, of high purity silicon tetrafluoride, starting from an aqueous solution of fluorosilicic acid, which comprises:(a) reacting an aqueous solution of fluorosilicic acid with concentrated sulphuric acid, carried out with a short residence time and preferably under fluido-dynamic conditions of turbulence, inside a reaction zone;(b) separating a gaseous stream containing silicon tetrafluoride from a liquid stream of aqueous sulphuric acid, carried out inside a separation zone, directly connected with the reaction zone;(c) washing said gaseous stream with concentrated and cold sulphuric acid carried out inside a washing zone, for the purpose of separating a gaseous stream of purified silicon tetrafluoride; and, possibly(d) further purifying said gaseous stream of purified silicon tetrafluoride by means of techniques of adsorption on an adsorbent solid material.

Abstract: Residual silicone from direct process manufacture of chlorosilanes is stabilized for transportation and disposal.

Abstract: The liquid or gaseous substances, such as hydrogen or trichlorosilane, enntered in the gas-phase deposition of silicon may contain n-type doping impurities which can be removed by adduct formation with silicon, titanium or tin halides. The impurities can be liberated from the adducts by thermal treatment and finally removed. The halides left behind are capable of again forming adducts and are again used to remove the impurities. The process can consequently be operated cyclically and is remarkable for the low quantity of chemicals required and for its ecological harmlessness.

Abstract: A method of redistributing a mixture of organohalosianes, particularly methylchlorosilanes by contacting said mixture with a heat treated crystalline gamma alumina or eta alumina catalyst.

Abstract: Chloropolysilanes can be produced in high yield without forming solid waste materials by contacting silicon materials with chlorine at a temperature of 140.degree..about.300.degree. C. in the presence of copper compound or a mixture thereof.

Abstract: By a chlorination process at a temperature exceeding 1000.degree. C. all hydrogenous compounds, including organic compounds, are converted into hydrogen-free compounds, e.g. CCl.sub.4, which do not interfere in the manufacture of optical fibres.

Abstract: Trichlorosilane, SiHCl.sub.3, is facilely prepared by (i) thermally reducing silicon tetrachloride, SiCl.sub.4, with hydrogen to produce reaction admixture comprising SiHCl.sub.3 and hydrochloric acid, said thermal reduction being carried out in a thermal plasma while tempering the reaction medium with a cooling gas, (ii) reacting said step (i) reaction admixture with elemental silicon at a temperature of from about 250.degree. to 350.degree. C. to produce SiHCl.sub.3 and hydrogen therefrom, and thence (iii) separating (iiia) the plasma-creating, hydrogen and cooling gases, and (iiib) product silicon chlorides therefrom.