초록

This invention discloses a process to improve reaction stability in the Direct Synthesis of trialkoxysilanes. The process is particularly effective in the Direct Synthesis of triethoxysilane and its higher alkyl cognates providing improved triethoxysilane yields.

대표청구항 ▼

The invention claimed is: 1. A process for the Direct Synthesis of trialkoxysilane comprising the steps of: a) forming a reaction mixture comprising a thermally stable solvent, silicon metal and a catalytically effective amount of a nanosized copper catalyst precursor; b) agitating and heating the

The invention claimed is: 1. A process for the Direct Synthesis of trialkoxysilane comprising the steps of: a) forming a reaction mixture comprising a thermally stable solvent, silicon metal and a catalytically effective amount of a nanosized copper catalyst precursor; b) agitating and heating the reaction mixture to form copper-activated silicon therein; and, c) adding to the reaction mixture (i) an alcohol R1OH wherein R1 is an alkyl group containing from 1 to 6 carbon atoms, (ii) a catalyst-promoting amount of at least one CN-containing promoter, wherein the promoter possesses the general formula X-(CN)n wherein X is a hydrocarbon group R2 of valence n containing from 1 to 40 carbon atoms, and optionally, silicon and/or etheric oxygen, and n is an integer with the value of 1 to 4, the alcohol reacting with the copper-activated silicon to provide trialkoxysilane HSi(OR1-)3 wherein R1 is as defined. 2. The process of claim 1 wherein the nanosized copper catalyst precursor is selected from the group consisting of nanosized copper, nanosized copper oxides, nanosized copper chlorides, other nanosized copper salts, and mixtures thereof. 3. The process of claim 2 wherein the nanosized copper catalyst precursor has diameters in the range from 1 nanometer (10-9 meter) to 100 nanometer (10-7 meter). 4. The process of claim 1 wherein the nanosized copper catalyst precursor is selected from the group comprising copper, copper (I) oxide, copper (II) oxide, copper (I) chloride, copper (II) chloride, copper (II) hydroxide, basic cupric oxide, basic copper carbonate, copper carboxylate, copper alkoxide and mixtures thereof. 5. The process of claim 1 wherein the mixture of step (b) is heated from 150�� C. to 350�� C. 6. The process of claim 1 wherein n is 1 and R2 is monovalent hydrocarbon group of up to 10 carbon atoms. 7. The process of claim 6 wherein the promoter is at least one member selected from the group consisting of acetonitrile, t-butyl nitrile, cyclohexyl nitrile, benzonitrile, benzyl nitrile, and mixtures thereof. 8. The process of claim 1 wherein n is 1 and R2 an etheric oxygen-containing group R3OR4 in which R3is a monovalent hydrocarbon group and R4 is a divalent hydrocarbon group, there being up to about 40 carbon atoms total in the etheric oxygen-containing group. 9. The process of claim 1 wherein n is 2 and R2 is an etheric oxygen-containing group R5OR6 in which R5 and R6 divalent hydrocarbon groups, there being up to about 40 carbon atoms total in the etheric oxygen-containing group. 10. The process of claim 1 wherein n is 1 and R2 is in which each R7 is the same or different monovalent hydrocarbon group of up to about 12 carbon atoms, one or more of which optionally contain etheric oxygen, R8 is a divalent hydrocarbon group of up to about 10 carbon atoms and m is 0 or 1. 11. The process of claim 10 wherein at least one R7 is selected from the group consisting of methoxy, ethoxy and propoxy. 12. The process of claim 1 wherein n is 2 and R2 is in which each R9 is the same or different monovalent hydrocarbon group of up to about 12 carbon atoms, one or both of which optionally contain etheric oxygen, each R10 is the same or different divalent hydrocarbon group of up to about 10 carbon atoms and p is 0 or 1. 13. The process of claim 12 wherein at least one R9 is selected from the group consisting of methyl, ethyl and propyl. 14. The process of claim 1 wherein n is 3 and R2 is in which each R11 is the same or different monovalent hydrocarbon group of up to about 12 carbon atoms, one or both of which optionally contain etheric oxygen, each R12 is the same or different divalent hydrocarbon group of up to about 10 carbon atoms and p is 1. 15. The process of claim 14 wherein at least one R11 is selected from the group consisting of methyl, ethyl and propyl. 16. The process of claim 1 wherein at least one promoter wherein X is hydrogen or a metal is combined with at least on promoter where X is R2. 17. The process of claim 1 wherein the promoter is a catalyst-promoting amount of acetonitrile and CuCl. 18. The process of claim 9 wherein the promoter is selected from the group consisting of CH2(CN)2, 1,1-dicyanocyclohexane, 1,2-dicyanobenzene and 1,4-dicyanocyclohexane, and mixtures thereof. 19. The process of claim 14 wherein the promoter is selected from the group consisting of 2,4,6-tricyanotoluene, 1,3,5-tricyanobenzene, tricyanoethoxypropane, and mixtures thereof. 20. The process of claim 1 wherein the promoter is selected from the group consisting of 1,1,2,2-tetracyanoethane, 1,2,4,5-tetracyanobenzene, and 2,2,3,3-tetracyanoethylene oxide, and mixtures thereof. 21. The process of claim 1 wherein the promoter has a particle size from about 10 micrometers to about 0.1 nanometer. 22. The process of claim 21 wherein the promoter has a particle size that is less than about 1 micrometer. 23. The process of claim 16 wherein the promoter is a mixture of CuCN and CH3(CH2)10CN. 24. The process of claim 16 wherein the promoter is a mixture of CuCN and CN(CH2)6CN. 25. The process of claim 1 wherein the promoter is present in an amount of about 100 parts per million to about 10 weight percent of the weight of silicon. 26. The process of claim 25 wherein the promoter is present in an amount from about 1000 parts per million to about 4 weight percent of the silicon. 27. The process of claim 5 wherein the promoter is present in an amount from about 100 parts per million to 6 weight percent of the silicon. 28. The process of claim 27 wherein the promoter is present in an amount from about 200 parts per million to about 4 weight percent of the silicon. 29. The process of claim 1 further comprising a foam control agent. 30. The process of claim 1 wherein the reaction temperature of step (c) is maintained at from 200�� C. to 280�� C. 31. The process of claim 1 wherein the silicon metal having a particle size of less than about 500 micron; one or more copper catalyst precursors having an average particle size from about 0.1 nm to about 600 nm, a surface area as low as 0.1 m2/g, in an amount from about 0.01 to about 5 parts by weight per 100 parts of said silicon metal such that about 0.008 to about 4.5 parts elemental copper is present based on 100 parts by weight of said silicon metal; the catalyst-promoting amount at least one promoter is from about 0.02 to about 6 parts by weight per 100 parts of said silicon metal; and a thermally stable reaction solvent present in an amount that provides a gravimetric ratio of solids to solvent of about 1:2 to about 1:4. 32. A trialkoxysilane produced by the process of claim 1. 33. A trialkoxysilane produced by the process of claim 1. 34. A trialkoxysilane produced by the process of claim 31. 35. A process for the Direct Synthesis of trialkoxysilane comprising the steps of: a) forming a reaction mixture comprising a thermally stable solvent, silicon metal and a catalytically effective amount of a copper catalyst precursor; b) agitating and heating the reaction mixture to form copper-activated silicon therein; and, c) adding the reaction mixture (i) an alcohol R1OH wherein R1 is an alkyl group containing from 1 to 6 carbon atoms, (ii) a catalyst-promoting amount of at least one CN-containing promoter, wherein the promoter possesses the general formula X--(CN)n wherein X is a hydrocarbon group R2 of valence n containing from 1 to 40 carbon atoms, and optionally, silicon and/or etheric oxygen, and n is an integer with the value of 1 to 4; the alcohol reacting with the copper-activated silicon to provide trialkoxysilane HSi(OR1)3 wherein R1 is defined. 36. A process for the Direct Synthesis of trialkoxysilane comprising the steps of: a) forming a reaction mixture comprising i) a thermally stable solvent in an amount that provides a gravimetric ratio of solids to solvent of about 1:2 to about 1:4, ii) silicon metal having a particle size of less than about 500 microns; and iii) a catalytically effective amount of a nanosized copper catalyst precursor having an average particle size from 0.1 nm to 600 nm and BET surface area of at least 0.1 m2/gram and in the amount from 0.01 to 5 parts by weight per 100 parts by weight a said silicon metal such that 0.008 to 4.5 parts elemental copper per 100 parts of said silicon metal; b) agitating and heating the reaction mixture to a temperature of between 190�� C. to 350�� to form nanosized copper catalysts precursor with an average particle size in the rang of from 1 nm to 100 nm which reacts with silicon metal to form a copper-activated silicon therein; and, c) adding to the reaction mixture maintained at a temperature from 190�� C. to 240�� C. i) an alcohol R1OH wherein R1 is an alkyl group containing from 2 to 6 carbon atoms, ii) a catalyst-promoting amount of at least one CN-containing promoter, wherein the promoter possesses the general formula X--(CN)n wherein X is a hydrogen or a metal with a valence of n and n is an integer with the value of 1 to 4; the alcohol reacting with the copper-activated silicon to provide trialkoxysilane HSi(OR1)3 wherein R1 is defined. 37. The process of claim 35 wherein the CN-containing promoter is selected from the group consisting of HCN, LiCN, NaCN, KCN, Ca(CN)2, Mg(CN)2, and Si(CN)4. 38. The process of claim 35 wherein the CN-containing promoter is selected from the group consisting of Cu(CN), Pd(CN)2, Ag(CN) and Ni(CN)2.