WO2014143402A1 - Method for making halosilanes from silica - Google Patents

Method for making halosilanes from silica Download PDF

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Publication number
WO2014143402A1
WO2014143402A1 PCT/US2014/011754 US2014011754W WO2014143402A1 WO 2014143402 A1 WO2014143402 A1 WO 2014143402A1 US 2014011754 W US2014011754 W US 2014011754W WO 2014143402 A1 WO2014143402 A1 WO 2014143402A1
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reactant
ingredient
alternatively
combination
halosilane
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PCT/US2014/011754
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French (fr)
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Dimitris Katsoulis
Wendy Sparschu
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Dow Corning Corporation
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/10—Magnesium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/08—Silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/44—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0201—Impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/06—Washing
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/06—Metal silicides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/08—Compounds containing halogen
    • C01B33/107—Halogenated silanes
    • C01B33/1071—Tetrachloride, trichlorosilane or silicochloroform, dichlorosilane, monochlorosilane or mixtures thereof
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/12—Organo silicon halides
    • C07F7/121—Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20
    • C07F7/125—Preparation or treatment not provided for in C07F7/14, C07F7/16 or C07F7/20 by reactions involving both Si-C and Si-halogen linkages, the Si-C and Si-halogen linkages can be to the same or to different Si atoms, e.g. redistribution reactions
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/12—Organo silicon halides
    • C07F7/16—Preparation thereof from silicon and halogenated hydrocarbons direct synthesis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/32—Reaction with silicon compounds, e.g. TEOS, siliconfluoride

Definitions

  • halosilanes are produced commercially by the Mueller-Rochow Direct Process, which comprises passing an organohalide compound over zero-valent silicon (SiO) in the presence of a copper catalyst and various optional promoters. Mixtures of halosilanes are produced by the Direct Process.
  • 0 used in the Direct Process is typically made by carbothermic reduction of S1O2 in an electric arc furnace. Extremely high temperatures are required to reduce the S1O2, so the process is energy intensive. Consequently, production of Si ⁇ adds costs to the Direct Process for producing halosilanes. Therefore, there is a need for a more economical method of producing halosilanes that avoids or reduces the need of producing SiO via this energy intensive carbothermic reduction process.
  • halosilanes find use in different industries. Tetrahalosilanes can be used as precursors to make organohalosilanes. Organohalosilanes are hydrolyzed to produce a wide range of polyorganosiloxanes, such as polydiorganosiloxanes and/or polyorganosiloxane resins.
  • a method for forming a reaction product comprising a halosilane is disclosed.
  • the method comprises:
  • halosilane has formula R n H m SiX(4- n . m ), where subscript n is 0 to 3, subscript m is 0 to 2, a quantity (n + m) ⁇ 3, each R is independently a hydrocarbyl group, and each X is independently a halogen atom.
  • the method for forming the reaction product comprising the halosilane comprises:
  • halosilane has formula R n H m SiX(4- n . m ), where subscript n is 0 to 3, subscript m is 0 to 2, a quantity (n + m) ⁇ 3, each R is independently a hydrocarbyl group, and each X is independently a halogen atom.
  • Ingredient (a) is silica, which is commercially available.
  • Ingredient (b) may be any species that can reduce silica.
  • Ingredient (b) may be a reducing agent selected from magnesium (Mg), aluminum (Al), zirconium (Zr), hafnium (Hf), calcium (Ca), titanium (Ti), carbon (C), boron (B), or a combination thereof.
  • ingredient (b) may be a reducing agent selected from sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), magnesium (Mg), aluminum (Al), zirconium (Zr), hafnium (Hf), calcium (Ca), titanium (Ti), carbon (C), boron (B), or a combination thereof.
  • Combinations include physical mixtures and/or alloys of two or more of the reducing agents.
  • ingredient (b) may be a group 1 metal of the periodic table of the elements, e.g., Na, K, Rb, and Cs.
  • the group 1 metal may be Na or K.
  • the group 1 metal may be Na.
  • the group 1 metal may be K.
  • alloys may be used as ingredient (b).
  • the alloy may be an alloy of two or more group 1 metals, for example, such alloys include sodium-potassium alloys, alloys containing two or more of K, Cs, and Rb with each other, and alternatively, alloys containing Na and further comprising one or more of K, Cs, and/or Rb may be used.
  • the alloy may be a sodium-potassium alloy.
  • ingredient (b) may be a group 2 metal of the periodic table of the elements or an alloy of said metals.
  • the group 2 metal may be selected from Mg, Ca, and alloys thereof.
  • ingredient (b) may be a group 4 metal of the periodic table of the elements or an alloy of said metals.
  • the group 4 metal may be selected from Zr, Hf, Ti, and alloys thereof.
  • ingredient (b) may be selected from Mg, Al, Zr, Hf, Ca, Ti, C, B, or a combination thereof.
  • ingredient (b) may be magnesium.
  • Ingredients (a) and (b) may be present in amounts sufficient to provide a molar ratio of ingredient (b) to ingredient (a) ((b):(a) ratio) of 0.25:1 to 4:1 , alternatively 2:1 to 4:1 .
  • Ingredient (b) is commercially available.
  • Ingredient (c) may be a metal halide of formula MX a , where M is a metal selected from the group consisting of chromium (Cr), manganese (Mn), iron (Fe), ruthenium (Ru), rhenium, (Re), rhodium (Rh), iridium (Ir), copper (Cu), cobalt (Co), molybdenum (Mo), nickel (Ni), palladium (Pd), platinum (Pt), and tungsten (W); subscript a is 1 to the maximum valance of the metal selected for M; and each X is independently a halogen atom.
  • M may be selected from Cu, Co, Mo, Ni, Pd, Pt, and W.
  • M may be selected from Cu, Pt, Ni, and Pd.
  • M may be selected from Cu, Ni, and Pt.
  • ingredient (c) may be PdX2- Ingredients (a) and (c) are present in amounts sufficient to provide a molar ratio of the amounts of metal atom M from ingredient (c) and the amount of Si from ingredient (a) (M:Si ratio) of 1 :2 to 1 :10.
  • the method described above may optionally further comprise steps (iv) and (v).
  • Step (iv) is contacting H2 with the spent reactant to re-activate the spent reactant, thereby re-forming the activated reactant; and step (v) is contacting additional organohalide with the activated reactant formed in step (iv).
  • the method may optionally further comprise step (vi): repeating steps (iv) and (v) one or more times. Alternatively, steps (iv) and (v) may be repeated 10 ⁇ or more times, alternatively 10 ⁇ to 10 7 times, and alternatively 2 to 15 times.
  • the method may optionally further comprise step (vii) repeating steps (i)-(v) one or more times.
  • the method may optionally further comprise step (viii) recovering the halosilane from the reaction product.
  • Step (i) of the method described above may be performed by (I)
  • ingredient (a) and (b) mechanochemically processing ingredients (a) and (b) to form a combination, and (II) combining the combination and ingredient (c).
  • the combination of ingredients (a) and (b) may be combined with ingredient (c) by ( 11 A) impregnating the combination with ingredient (c), and/or (MB) mechanochemically processing the combination and ingredient (c).
  • ingredient (b) acts as a reducing agent of silica (oxygen getter)
  • combining ingredients (a) and (b) before adding ingredient (c) may generate elemental silicon and possibly silicon that has weak associations with the surrounding oxygen atoms.
  • the combining of ingredient (c) that follows may generate a silicide species upon exposure to high temperature H2, which become the precursor for the chlorosilanes upon reaction with the organohalide.
  • Step (i) may be performed at ambient temperature or with heating, e.g., temperature in step (i) may be 23 °C to 600 °C, alternatively 23 ⁇ C to 200 °C, and alternatively 23 ⁇ C to 150°C, and alternatively 23 ⁇ C to 40 °C.
  • the time for step (i) depends on various factors including the temperature and amount of ingredient (b) selected. However, mechanochemically processing in step (i) may be performed for up to 48 hours, alternatively up to 24 hours, and alternatively 1 to 4 hours.
  • Step (ii) and step (iii) of the method may be performed separately and consecutively.
  • step (ii) and step (iii) do not overlap or coincide.
  • step (iii) is performed after step (ii) in the method; however, additional steps may be performed before step (i), between steps (ii) and (iii), and/or after step (iii), as described herein.
  • step (iii) is performed after step (ii) in the method; however, additional steps may be performed before step (i), between steps (ii) and (iii), and/or after step (iii), as described herein.
  • step (iii) is performed after step (ii) in the method; however, additional steps may be performed before step (i), between steps (ii) and (iii), and/or after step (iii), as described herein.
  • “Separately” refers to either spatially or temporally or both.
  • Consecutively refers to temporally (and furthermore occurring in a defined order).
  • the organohalide used in step (iii) of the method described above may have the formula RX, where R is a monovalent organic group and X is a halogen.
  • R may be a hydrocarbyl selected from the group consisting of alkyl, aralkyi, alkenyl, alkynyl, aryl, and carbocyclic, as defined herein.
  • R may be an alkyl group or a cycloalkyl group.
  • the alkyl groups for R may have 1 to 10 carbon atoms, alternatively 1 to 6 carbon atoms, and alternatively 1 to 4 carbon atoms.
  • the cycloalkyl groups for R may have 4 to 10 carbon atoms, alternatively 6 to 8 carbon atoms.
  • Alkyl groups containing at least three carbon atoms may have a branched or unbranched structure.
  • R may be Me, Et, or Ph.
  • R may be Me.
  • X may be Br, CI or I; alternatively Br or CI; and alternatively CI.
  • the organohalide include, but are not limited to, methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, cyclobutyl chloride, cyclobutyl bromide, cyclohexyl chloride, and cyclohexyl bromide.
  • the organohalide may be an aliphatic hydrocarbyl halide.
  • the aliphatic hydrocarbyl halide may be a compound of formula H y CvX 7 ., where subscript x represents average number of hydrogen atoms present, subscript y represents average number of carbon atoms present, and subscript z represents average number of halogen atoms present. Subscript x is 0 or more, subscript y is 1 or more, and subscript z is 1 or more.
  • a quantity (x + z) a quantity (2y + 2).
  • the organohalide is a monocyclic cycloalkyl halide
  • the quantity (x + z) 2y.
  • Each X is independently a halogen atom, as described above.
  • subscript y may be 1 to 10, alternatively 1 to 6, alternatively 1 to 4, and alternatively 1 .
  • subscript z may be 1 to 4.
  • subscript z may be at least 2, alternatively 2 to 4.
  • suitable organohalides include, but are not limited to, methyl chloride (H3CCI), methylene chloride (H2CCI2), chloroform
  • Steps (ii) and (iii) of the method described herein can be performed in any reactor suitable for the combining of gases and solids.
  • steps (ii) and (iii) may be performed in the same reactor.
  • steps (ii) and (iii) may be performed in different reactors.
  • the reactor configuration for each of steps (ii) and (iii) can be a batch vessel, packed bed, stirred bed, vibrating bed, moving bed, recirculating beds, or a fluidized bed.
  • the reactor may be a packed bed, a stirred bed, or a fluidized bed.
  • the reactor should have means to control the temperature of the reaction zone, i.e., the portion of the reactor in which the H2 contacts the reactant in step (ii) and the portion of the reactor in which the organohalide contacts the activated reactant in step (iii).
  • the temperature at which the H2 and the reactant are contacted in step (ii) of the method described above is at 500 °C to 1000 ⁇ €, alternatively 500 ⁇ € to 850 °C.
  • step (iii) if temperature is less than 500 °C, then the reactant may not be activated sufficiently to react in step (iii); and if the temperature is greater than ⁇ ⁇ ' ⁇ , then the reactant may decompose.
  • the pressure at which the H2 and the reactant are contacted can be sub- atmospheric, atmospheric, or super-atmospheric.
  • the pressure may range from 0 kilopascals gauge (kPag) to 2000 kPag; alternatively 100 kPag to 1000 kPag; and alternatively 100 kPag to 800 kPag.
  • the residence time for the H2 to contact the reactant in step (ii) is sufficient to form the activated reactant.
  • a sufficient residence time may be at least 0.01 seconds (s); alternatively at least 0.1 s; alternatively from 0.1 s to 10 minutes (min); alternatively from 0.1 s to 1 min ; and alternatively from 1 s to 1 0 s.
  • the desired residence time may be achieved by adjusting the flow rate of the H2, or by adjusting the total reactor volume, or by any combination thereof.
  • the temperature at which the organohalide and the activated reactant are contacted in step (iii) of the method described above is 200 ⁇ to 500 ' ⁇ , alternatively 250 °C to 400 °C, and alternatively 300 °C to 400 ⁇ €.
  • temperature is less than 200 °C, then the halosilane may not be formed in step (iii) ; and if the temperature is greater than 500 ' ⁇ , then the
  • organohalide may decompose.
  • the pressure at which the organohalide and the activated reactant are contacted can be sub-atmospheric, atmospheric, or super-atmospheric.
  • the pressure may range from 0 kilopascals gauge (kPag) to 2000 kPag; alternatively 100 kPag to 1 000 kPag; and alternatively 100 kPag to 800 kPag.
  • the residence time for the organohalide to contact the activated reactant in step (iii) is sufficient to form the halosilane.
  • a sufficient residence time may be at least 0.01 s, alternatively, up to 2 h, and alternatively 0.1 s to 2 h.
  • the desired residence time may be achieved by adjusting the flow rate of the organohalide, or by adjusting the total reactor volume, or by any combination thereof.
  • the method may further comprise pre-heating and vaporizing the organohalide by known methods before contacting the organohalide with the activated reactant in step (iii).
  • the method may further comprise pre-heating above the melting point and liquefying or vaporizing the organohalide before contacting it with the activated reactant in step (iii).
  • the method described above may optionally further comprise steps (iv) and (v).
  • Step (iv) is contacting H2 with the spent reactant to re-activate the spent reactant, thereby re-forming the activated reactant; and step (v) is contacting additional organohalide with the activated reactant formed in step (iv).
  • the method may optionally further comprise step (vi) : repeating steps (iv) and (v) one or more times.
  • steps (iv) and (v) may be repeated 1 0 ⁇ or more times, alternatively 1 0 ⁇ to 10 7 times, and alternatively 2 to 15 times.
  • step (iv) the description of the conditions (e.g., temperature, pressure, ar- 1 — t; — x ⁇ f ⁇ + — 1 ; - may also apply to step (iv); and the description of the conditions of step (iii) may also apply to step (v).
  • steps (iv) and (v) may be repeated until the silicon is spent; e.g., insufficient silicon is present to continue producing the halosilane. When this happens, step (i) may be repeated to add additional reactant, and steps (ii)-(v) may be repeated.
  • the method may optionally further comprise step (viii).
  • Step (viii) comprises recovering the halosilane from the reaction product.
  • the halosilane may be recovered from the reaction product by, for example, removing gaseous product from the reactor followed by isolation by distillation.
  • the reaction product produced by the method described herein comprises a halosilane of formula R n H m SiX(4- n . m ), where subscripts n and m, and R and X, are as described above.
  • R is hydrocarbyl and X is a halogen; alternatively, each R is alkyl and each X is CI.
  • Exemplary halosilanes include organotrihalosilanes and/or diorganodihalosilanes.
  • Organotrihalosilanes are exemplified by methyltrichlorosilane, methyltribromosilane, and ethyltrichlorosilane.
  • Examples of diorganodihalosilanes prepared according to the present process include, but are not limited to, dimethyldichlorosilane (i.e., (CH3)2SiCl2), dimethyldibromosilane,
  • diethyldichlorosilane diethyldibromosilane
  • diethyldibromosilane examples include, but are not limited to, methyltrichlorosilane (i.e., CH3S1CI3), and methyltribromosilane (i.e., CH3SiBr3).
  • the halosilanes produced by the method described herein may be hydrolyzed in known processes for producing polyorganosiloxanes.
  • the polyorganosiloxanes thus produced find use in many industries and applications.
  • the method can produce halosilanes, such as chlorosilanes, directly from SiC ⁇ . Without wishing to be bound by theory, it is thought that the method described herein provides the benefits that SiO is not isolated, and the starting material, S1O2, is inexpensive and readily available.
  • the method may be used to produce diorganodihalosilanes, such as Me2SiCl2 with minimal amounts of S1CI4 being produced
  • Comparative Example A A sample of S1O2 was ball milled for 30 min to decrease the particle size and increase the surface area. The resulting milled S1O2 was then reacted with H3CCI (MeCI). A peak identified in GC-TCD as MeHSiCl2 was observed in the reactor effluent at an instantaneous maximum 0.15% yield.
  • Comparative Example B Magnesium was ball milled with S1O2 in a 4:1 molar ratio for 1 hour and with S1O2 in a 2:1 ratio for 4 hours. The resulting Mg-Si02 combinations were then reacted with H3CCI (MeCI). The 4:1 Mg:Si02 reaction with H3CCI (MeCI) resulted in very small peaks in the GC-TCD spectra that were identified as MeSiCl3 and Me2SiCl2- The XRD detected MgO, silicon, Mg2SiC>4 and S1O2. The presence of silicon in the material most likely accounts for the chlorosilanes observed in the GC-TCD of the reactor effluent.
  • the activation was performed with 100 seem H2 at 850 ⁇ for 2-3 hours.
  • the reaction tube was then cooled to 300 °C while H2 flow continued at 10 seem. Once 300 °C was reached, the H2 was turned off, and the H3CCI (MeCI) feed was started at 1 .86 seem.
  • Samples were taken from the reaction stream and injected into a GC-TCD for analysis using an online switching valve. Total H3CCI (MeCI) reaction time was 2 hours.
  • Table 1 List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
  • 0.5 g of 1 :2.5 PdCl2:Mg-Si02 was loaded into a glass tube. The activation was performed with 100 seem H2 at 850 ⁇ for 2-3 hours. The reaction tube was then cooled to 300 °C while H2 flow continued at 10 seem. Once 300 °C was reached, the H2 was turned off, and the
  • H3CCI (MeCI) feed was started at 1 .86 seem. Samples were taken from the reaction stream and injected into a GC-TCD for analysis using an online switching valve. Total H3CCI (MeCI) reaction time was 2 hours.
  • Example 3 - 1 :3 Pd:Si molar ratio - In a flow reactor, 0.5 g of 1 :3 PdC ⁇ Mg- S1O2 was loaded into a glass tube. The Activation was performed with 100 seem H2 at
  • Table 3 List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
  • PdCl2:Mg-Si02 was loaded into a glass tube. The activation was performed with 100 seem H2 at 850 ⁇ for 2-3 hours. The reaction tube was then cooled to 300 °C while H2 flow continued at 10 seem. Once 300 °C was reached, the H2 was turned off, and the H3CCI (MeCI) feed was started at 1 .86 seem. Samples were taken from the reaction stream and injected into a GC-TCD for analysis using an online switching valve. Total H3CCI (MeCI) reaction time was 2 hours.
  • Table 4 List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
  • Example 5 - 1 :6 Pd:Si molar ratio - Example 4 was repeated, except using 0.5 g of 1 :6 PdCl2:Mg-Si02 (instead of 0.5 g of 1 :4.4 PdCl2:Mg-Si02).
  • Table 5 List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
  • Alkyl means an acyclic, branched or unbranched, saturated monovalent hydrocarbon group.
  • alkyl groups include Me, Et, Pr, 1 -methylethyl, Bu, 1 - methylpropyl, 2-methylpropyl, 1 ,1 -dimethylethyl, 1 -methylbutyl, 1 -ethylpropyl, pentyl, 2- methylbutyl, 3-methylbutyl, 1 ,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, 2- ethylhexyl, octyl, nonyl, and decyl.
  • Alkyl groups have at least one carbon atom.
  • alkyl groups may have 1 to 12 carbon atoms, alternatively 1 to 10 carbon atoms, alternatively 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, alternatively 1 to 2 carbon atoms, and alternatively 1 carbon atom.
  • Alkyl and “alkaryl” each refer to an alkyl group having a pendant and/or terminal aryl group or an aryl group having a pendant alkyl group.
  • exemplary aralkyl groups include benzyl, tolyl, xylyl, phenylethyl, phenyl propyl, and phenyl butyl.
  • Aralkyl groups have at least 4 carbon atoms.
  • Monocyclic aralkyl groups may have 4 to 12 carbon atoms, alternatively 4 to 9 carbon atoms, and alternatively 4 to 7 carbon atoms.
  • Polycyclic aralkyl groups may have 7 to 17 carbon atoms, alternatively 7 to 14 carbon atoms, and alternatively 9 to 10 carbon atoms.
  • Alkenyl means an acyclic, branched, or unbranched unsaturated monovalent hydrocarbon group, where the monovalent hydrocarbon group has a double bond.
  • Alkenyl groups include Vi, allyl, propenyl, and hexenyl. Alkenyl groups have at least 2 carbon atoms. Alternatively, alkenyl groups may have 2 to 12 carbon atoms,
  • Alkynyl means an acyclic, branched, or unbranched unsaturated monovalent hydrocarbon group, where the monovalent hydrocarbon group has a triple bond.
  • Alkynyl groups include ethynyl and propynyl. Alkynyl groups have at least 2 carbon atoms. Alternatively, alkynyl groups may have 2 to 12 carbon atoms, alternatively 2 to 10 carbon atoms, alternatively 2 to 6 carbon atoms, alternatively 2 to 4 carbon atoms, and alternatively 2 carbon atoms.
  • Aryl means a cyclic, fully unsaturated, hydrocarbon group.
  • Aryl is exemplified by, but not limited to, Ph and naphthyl.
  • Aryl groups have at least 5 carbon atoms.
  • Monocyclic aryl groups may have 6 to 9 carbon atoms, alternatively 6 to 7 carbon atoms, and alternatively 6 carbon atoms.
  • Polycyclic aryl groups may have 10 to 17 carbon atoms, alternatively 10 to 14 carbon atoms, and alternatively 12 to 14 carbon atoms.
  • Carbocycle and “carbocyclic” refer to a hydrocarbon ring. Carbocycles may be monocyclic or alternatively may be fused, bridged, or spiro polycyclic rings.
  • Carbocycles have at least 3 carbon atoms.
  • Monocyclic carbocycles may have 3 to 9 carbon atoms, alternatively 4 to 7 carbon atoms, and alternatively 5 to 6 carbon atoms.
  • Polycyclic carbocycles may have 7 to 17 carbon atoms, alternatively 7 to 14 carbon atoms, and alternatively 9 to 10 carbon atoms.
  • Carbocycles may be saturated or partially unsaturated.
  • Cycloalkyl refers to a saturated hydrocarbon group including a saturated carbocycle. Cycloalkyl groups are exemplified by cyclobutyl, cyclopentyl, cyclohexyl, and methylcyclohexyl. Cycloalkyl groups have at least 3 carbon atoms. Monocyclic cycloalkyl groups may have 3 to 9 carbon atoms, alternatively 4 to 7 carbon atoms, and alternatively 5 to 6 carbon atoms. Polycyclic cycloalkyl groups may have 7 to 17 carbon atoms, alternatively 7 to 14 carbon atoms, and alternatively 9 to 10 carbon atoms.
  • Metallic means that the metal has an oxidation number of zero.
  • Residence time means the time which a material takes to pass through a reactor system in a continuous process, or the time a material spends in the reactor in a batch process.
  • residence time may refer to the time during which one reactor volume of the reactant makes contact with H2 in step (ii) of the method; or the time during which one reactor volume of the activated reactant makes contact with the organohalide in step (iii) as the reactant or activated reactant passes through the reactor system in a continuous process or during which the reactant or activated reactant is placed within the reactor in a batch process.
  • residence time may refer to the time for one reactor volume of reactant gases to pass through a reactor charged with the reactant or activated reactant, e.g., the time for one reactor volume of the
  • organohalide to pass through a reactor charged with the activated reactant.
  • Mechanochemically processing means applying mechanical energy to initiate chemical reactions and/or structural changes.
  • Mechanochemically processing may be performed, for example, by techniques such as milling, e.g., ball milling. Milling may be performed using any convenient milling equipment such as a mixer mill, planetary mill, attritor, or ball mill.
  • Mechanochemical processing may be performed, for example, using the methods and equipment described in, "Mechanical alloying and milling" by C.
  • Step (iii) refers to the reactant after it has been contacted with the organohalide in step (iii) (or after step (v), when step (v) is present in the method).
  • the spent reactant after step (iii) (or step (v)) is the mass that remained in the reactor when the yield of the organosilane volatile components was reduced to trace amounts. This can be after step (iii) or step (v), when step (v) is present in the method.
  • ranges includes the range itself and also anything subsumed therein, as well as endpoints.
  • disclosure of a range of 2.0 to 4.0 includes not only the range of 2.0 to 4.0, but also 2.1 , 2.3, 3.4, 3.5, and 4.0 individually, as well as any other number subsumed in the range.
  • disclosure of a range of, for example, 2.0 to 4.0 includes the subsets of, for example, 2.1 to 3.5, 2.3 to 3.4, 2.6 to 3.7, and 3.8 to 4.0, as well as any other subset subsumed in the range.
  • any ranges and subranges relied upon in describing various embodiments of the present disclosure independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein.
  • the enumerated ranges and subranges sufficiently describe and enable various embodiments of the present disclosure, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on.
  • a range "of 200 to 1400" may be further delineated into a lower third, i.e., from 200 to 600, a middle third, i.e., from 600 to 1000, and an upper third, i.e., from 1000 to 1400, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims.
  • a range which defines or modifies a range, such as "at least,” “greater than,” “less than,” “no more than,” and the like, it is to be understood that such language includes subranges and/or an upper or lower limit.
  • a range of "at least 0.1 %” inherently includes a subrange from 0.1 % to 35%, a subrange from 10% to 25%, a subrange from 23% to 30%, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims.
  • an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims.
  • a range of "1 to 9" includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1 , which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.

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Abstract

A method includes: (i) combining ingredients to form a reactant, (ii) contacting H2 with the reactant to form an activated reactant; and (iii) contacting an organohalide with the activated reactant to form a spent reactant and a reaction product including a halosilane. The ingredients used in step (i) are: (a) SiO2, (b) a reducing agent, and (c) a silicide precursor. The halosilane produced by the method has formula RnHmSiX(4-n), where subscript n is 0 to 3, subscript m is 0 to 2, a quantity (n + m) ≤ 3, each R is independently a hydrocarbyl group, and each X is independently a halogen atom.

Description

METHOD FOR MAKING HALOSILANES FROM SILICA
[0001] Methods of preparing halosilanes are known in the art. Typically, halosilanes are produced commercially by the Mueller-Rochow Direct Process, which comprises passing an organohalide compound over zero-valent silicon (SiO) in the presence of a copper catalyst and various optional promoters. Mixtures of halosilanes are produced by the Direct Process.
[0002] The S|0 used in the Direct Process is typically made by carbothermic reduction of S1O2 in an electric arc furnace. Extremely high temperatures are required to reduce the S1O2, so the process is energy intensive. Consequently, production of Si^ adds costs to the Direct Process for producing halosilanes. Therefore, there is a need for a more economical method of producing halosilanes that avoids or reduces the need of producing SiO via this energy intensive carbothermic reduction process.
[0003] Various halosilanes find use in different industries. Tetrahalosilanes can be used as precursors to make organohalosilanes. Organohalosilanes are hydrolyzed to produce a wide range of polyorganosiloxanes, such as polydiorganosiloxanes and/or polyorganosiloxane resins.
BRIEF SUMMARY OF THE INVENTION
[0004] A method for forming a reaction product comprising a halosilane is disclosed.
The method comprises:
(i) combining ingredients to form a reactant, where the ingredients comprise
(a) Si02,
(b) a reducing agent, and
(c) a silicide precursor;
(ii) contacting H2 with the reactant to form an activated reactant; and
(iii) contacting an organohalide with the activated reactant to form a spent reactant and the halosilane, where the halosilane has formula RnHmSiX(4-n.m), where subscript n is 0 to 3, subscript m is 0 to 2, a quantity (n + m) < 3, each R is independently a hydrocarbyl group, and each X is independently a halogen atom.
DETAILED DESCRPTION OF THE INVENTION
[0005] The Brief Summary of the Invention and the Abstract are hereby incorporated by reference. All ratios, percentages, and other amounts are by weight, unless otherwise indicated. [0006] The method for forming the reaction product comprising the halosilane comprises:
(i) combining ingredients to form a reactant, where the ingredients comprise
(a) Si02,
(b) a reducing agent, and
(c) a silicide precursor;
(ii) contacting H2 with the reactant to form an activated reactant; and
(iii) contacting an organohalide with the activated reactant to form a spent reactant and the halosilane, where the halosilane has formula RnHmSiX(4-n.m), where subscript n is 0 to 3, subscript m is 0 to 2, a quantity (n + m) < 3, each R is independently a hydrocarbyl group, and each X is independently a halogen atom.
[0007] Ingredient (a) is silica, which is commercially available. Ingredient (b) may be any species that can reduce silica. Ingredient (b) may be a reducing agent selected from magnesium (Mg), aluminum (Al), zirconium (Zr), hafnium (Hf), calcium (Ca), titanium (Ti), carbon (C), boron (B), or a combination thereof. Alternatively, ingredient (b) may be a reducing agent selected from sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), magnesium (Mg), aluminum (Al), zirconium (Zr), hafnium (Hf), calcium (Ca), titanium (Ti), carbon (C), boron (B), or a combination thereof. Combinations include physical mixtures and/or alloys of two or more of the reducing agents.
[0008] For example, ingredient (b) may be a group 1 metal of the periodic table of the elements, e.g., Na, K, Rb, and Cs. Alternatively, the group 1 metal may be Na or K. Alternatively, the group 1 metal may be Na. Alternatively, the group 1 metal may be K.
[0009] Alternatively, alloys may be used as ingredient (b). The alloy may be an alloy of two or more group 1 metals, for example, such alloys include sodium-potassium alloys, alloys containing two or more of K, Cs, and Rb with each other, and alternatively, alloys containing Na and further comprising one or more of K, Cs, and/or Rb may be used. Alternatively, the alloy may be a sodium-potassium alloy.
[0010] Alternatively, ingredient (b) may be a group 2 metal of the periodic table of the elements or an alloy of said metals. The group 2 metal may be selected from Mg, Ca, and alloys thereof.
[0011] Alternatively, ingredient (b) may be a group 4 metal of the periodic table of the elements or an alloy of said metals. The group 4 metal may be selected from Zr, Hf, Ti, and alloys thereof. [0012] Alternatively, ingredient (b) may be selected from Mg, Al, Zr, Hf, Ca, Ti, C, B, or a combination thereof. Alternatively, ingredient (b) may be magnesium. Ingredients (a) and (b) may be present in amounts sufficient to provide a molar ratio of ingredient (b) to ingredient (a) ((b):(a) ratio) of 0.25:1 to 4:1 , alternatively 2:1 to 4:1 . Ingredient (b) is commercially available.
[0013] Ingredient (c) may be a metal halide of formula MXa, where M is a metal selected from the group consisting of chromium (Cr), manganese (Mn), iron (Fe), ruthenium (Ru), rhenium, (Re), rhodium (Rh), iridium (Ir), copper (Cu), cobalt (Co), molybdenum (Mo), nickel (Ni), palladium (Pd), platinum (Pt), and tungsten (W); subscript a is 1 to the maximum valance of the metal selected for M; and each X is independently a halogen atom. Alternatively, M may be selected from Cu, Co, Mo, Ni, Pd, Pt, and W. Alternatively, M may be selected from Cu, Pt, Ni, and Pd. Alternatively, M may be selected from Cu, Ni, and Pt. Alternatively, ingredient (c) may be PdX2- Ingredients (a) and (c) are present in amounts sufficient to provide a molar ratio of the amounts of metal atom M from ingredient (c) and the amount of Si from ingredient (a) (M:Si ratio) of 1 :2 to 1 :10.
[0014] The method described above may optionally further comprise steps (iv) and (v). Step (iv) is contacting H2 with the spent reactant to re-activate the spent reactant, thereby re-forming the activated reactant; and step (v) is contacting additional organohalide with the activated reactant formed in step (iv). The method may optionally further comprise step (vi): repeating steps (iv) and (v) one or more times. Alternatively, steps (iv) and (v) may be repeated 10^ or more times, alternatively 10^ to 107 times, and alternatively 2 to 15 times. The method may optionally further comprise step (vii) repeating steps (i)-(v) one or more times. The method may optionally further comprise step (viii) recovering the halosilane from the reaction product.
[0015] Step (i) of the method described above may be performed by (I)
mechanochemically processing ingredients (a) and (b) to form a combination, and (II) combining the combination and ingredient (c). The combination of ingredients (a) and (b) may be combined with ingredient (c) by ( 11 A) impregnating the combination with ingredient (c), and/or (MB) mechanochemically processing the combination and ingredient (c). Without wishing to be bound by theory, it is thought that ingredient (b) acts as a reducing agent of silica (oxygen getter), and combining ingredients (a) and (b) before adding ingredient (c) may generate elemental silicon and possibly silicon that has weak associations with the surrounding oxygen atoms. The combining of ingredient (c) that follows may generate a silicide species upon exposure to high temperature H2, which become the precursor for the chlorosilanes upon reaction with the organohalide.
[0016] Step (i) may be performed at ambient temperature or with heating, e.g., temperature in step (i) may be 23 °C to 600 °C, alternatively 23 <C to 200 °C, and alternatively 23 <C to 150°C, and alternatively 23 <C to 40 °C. The time for step (i) depends on various factors including the temperature and amount of ingredient (b) selected. However, mechanochemically processing in step (i) may be performed for up to 48 hours, alternatively up to 24 hours, and alternatively 1 to 4 hours.
[0017] The method described above further comprises step (ii) and step (iii). Step (ii) and step (iii) of the method may be performed separately and consecutively.
"Separately" means that step (ii) and step (iii) do not overlap or coincide.
"Consecutively" means that step (iii) is performed after step (ii) in the method; however, additional steps may be performed before step (i), between steps (ii) and (iii), and/or after step (iii), as described herein. "Separately" refers to either spatially or temporally or both. "Consecutively" refers to temporally (and furthermore occurring in a defined order).
[0018] The organohalide used in step (iii) of the method described above may have the formula RX, where R is a monovalent organic group and X is a halogen. R may be a hydrocarbyl selected from the group consisting of alkyl, aralkyi, alkenyl, alkynyl, aryl, and carbocyclic, as defined herein. Alternatively, R may be an alkyl group or a cycloalkyl group. The alkyl groups for R may have 1 to 10 carbon atoms, alternatively 1 to 6 carbon atoms, and alternatively 1 to 4 carbon atoms. The cycloalkyl groups for R may have 4 to 10 carbon atoms, alternatively 6 to 8 carbon atoms. Alkyl groups containing at least three carbon atoms may have a branched or unbranched structure. Alternatively, R may be Me, Et, or Ph. Alternatively, R may be Me. Alternatively, X may be Br, CI or I; alternatively Br or CI; and alternatively CI. Examples of the organohalide include, but are not limited to, methyl chloride, methyl bromide, methyl iodide, ethyl chloride, ethyl bromide, ethyl iodide, cyclobutyl chloride, cyclobutyl bromide, cyclohexyl chloride, and cyclohexyl bromide.
[0019] Alternatively, the organohalide may be an aliphatic hydrocarbyl halide. The aliphatic hydrocarbyl halide may be a compound of formula HyCvX7., where subscript x represents average number of hydrogen atoms present, subscript y represents average number of carbon atoms present, and subscript z represents average number of halogen atoms present. Subscript x is 0 or more, subscript y is 1 or more, and subscript z is 1 or more. When the organohalide is a noncyclic aliphatic hydrocarbyl halide, then a quantity (x + z) = a quantity (2y + 2). When the organohalide is a monocyclic cycloalkyl halide, then the quantity (x + z) = 2y. Each X is independently a halogen atom, as described above. Alternatively, subscript y may be 1 to 10, alternatively 1 to 6, alternatively 1 to 4, and alternatively 1 . Alternatively, subscript z may be 1 to 4. Alternatively, subscript z may be at least 2, alternatively 2 to 4. Examples of suitable organohalides include, but are not limited to, methyl chloride (H3CCI), methylene chloride (H2CCI2), chloroform
(HCCI3), carbon tetrachloride (CCI4), and dichloroethane.
[0020] Steps (ii) and (iii) of the method described herein can be performed in any reactor suitable for the combining of gases and solids. In one embodiment, steps (ii) and (iii) may be performed in the same reactor. Alternatively, steps (ii) and (iii) may be performed in different reactors. However, the reactor configuration for each of steps (ii) and (iii) can be a batch vessel, packed bed, stirred bed, vibrating bed, moving bed, recirculating beds, or a fluidized bed. Alternatively, the reactor may be a packed bed, a stirred bed, or a fluidized bed. To facilitate reaction, the reactor should have means to control the temperature of the reaction zone, i.e., the portion of the reactor in which the H2 contacts the reactant in step (ii) and the portion of the reactor in which the organohalide contacts the activated reactant in step (iii).
[0021] The temperature at which the H2 and the reactant are contacted in step (ii) of the method described above is at 500 °C to 1000 <€, alternatively 500 <€ to 850 °C.
Without wishing to be bound by theory, it is thought that if temperature is less than 500 °C, then the reactant may not be activated sufficiently to react in step (iii); and if the temperature is greater than Ι ΟΟΟ 'Ό, then the reactant may decompose.
[0022] The pressure at which the H2 and the reactant are contacted can be sub- atmospheric, atmospheric, or super-atmospheric. For example, the pressure may range from 0 kilopascals gauge (kPag) to 2000 kPag; alternatively 100 kPag to 1000 kPag; and alternatively 100 kPag to 800 kPag.
[0023] The residence time for the H2 to contact the reactant in step (ii) is sufficient to form the activated reactant. For example, a sufficient residence time may be at least 0.01 seconds (s); alternatively at least 0.1 s; alternatively from 0.1 s to 10 minutes (min); alternatively from 0.1 s to 1 min ; and alternatively from 1 s to 1 0 s. The desired residence time may be achieved by adjusting the flow rate of the H2, or by adjusting the total reactor volume, or by any combination thereof.
[0024] The temperature at which the organohalide and the activated reactant are contacted in step (iii) of the method described above is 200 ^ to 500 'Ό, alternatively 250 °C to 400 °C, and alternatively 300 °C to 400 <€. Without wishing to be bound by theory, it is thought that if temperature is less than 200 °C, then the halosilane may not be formed in step (iii) ; and if the temperature is greater than 500 'Ό, then the
organohalide may decompose.
[0025] The pressure at which the organohalide and the activated reactant are contacted can be sub-atmospheric, atmospheric, or super-atmospheric. For example, the pressure may range from 0 kilopascals gauge (kPag) to 2000 kPag; alternatively 100 kPag to 1 000 kPag; and alternatively 100 kPag to 800 kPag.
[0026] The residence time for the organohalide to contact the activated reactant in step (iii) is sufficient to form the halosilane. For example, a sufficient residence time may be at least 0.01 s, alternatively, up to 2 h, and alternatively 0.1 s to 2 h. The desired residence time may be achieved by adjusting the flow rate of the organohalide, or by adjusting the total reactor volume, or by any combination thereof.
[0027] If the organohalide is a liquid at or below standard temperature and pressure, the method may further comprise pre-heating and vaporizing the organohalide by known methods before contacting the organohalide with the activated reactant in step (iii).
[0028] If the organohalide is a solid at or below standard temperature and pressure, the method may further comprise pre-heating above the melting point and liquefying or vaporizing the organohalide before contacting it with the activated reactant in step (iii).
[0029] The method described above may optionally further comprise steps (iv) and (v). Step (iv) is contacting H2 with the spent reactant to re-activate the spent reactant, thereby re-forming the activated reactant; and step (v) is contacting additional organohalide with the activated reactant formed in step (iv). The method may optionally further comprise step (vi) : repeating steps (iv) and (v) one or more times. Alternatively, steps (iv) and (v) may be repeated 1 0^ or more times, alternatively 1 0^ to 107 times, and alternatively 2 to 15 times. For the sake of brevity, the description of the conditions (e.g., temperature, pressure, ar-1— t;— x ~f ~+— 1 ;- may also apply to step (iv); and the description of the conditions of step (iii) may also apply to step (v). Without wishing to be bound by theory, it is thought that steps (iv) and (v) may be repeated until the silicon is spent; e.g., insufficient silicon is present to continue producing the halosilane. When this happens, step (i) may be repeated to add additional reactant, and steps (ii)-(v) may be repeated.
[0030] The method may optionally further comprise step (viii). Step (viii) comprises recovering the halosilane from the reaction product. The halosilane may be recovered from the reaction product by, for example, removing gaseous product from the reactor followed by isolation by distillation. The reaction product produced by the method described herein comprises a halosilane of formula RnHmSiX(4-n.m), where subscripts n and m, and R and X, are as described above. Alternatively, R is hydrocarbyl and X is a halogen; alternatively, each R is alkyl and each X is CI. Exemplary halosilanes include organotrihalosilanes and/or diorganodihalosilanes. Organotrihalosilanes are exemplified by methyltrichlorosilane, methyltribromosilane, and ethyltrichlorosilane. Examples of diorganodihalosilanes prepared according to the present process include, but are not limited to, dimethyldichlorosilane (i.e., (CH3)2SiCl2), dimethyldibromosilane,
diethyldichlorosilane, and diethyldibromosilane. Examples of other organohalosilanes that may be produced in addition to the diorganodihalosilane include, but are not limited to, methyltrichlorosilane (i.e., CH3S1CI3), and methyltribromosilane (i.e., CH3SiBr3).
[0031] The halosilanes produced by the method described herein may be hydrolyzed in known processes for producing polyorganosiloxanes. The polyorganosiloxanes thus produced find use in many industries and applications. The method can produce halosilanes, such as chlorosilanes, directly from SiC^. Without wishing to be bound by theory, it is thought that the method described herein provides the benefits that SiO is not isolated, and the starting material, S1O2, is inexpensive and readily available.
Furthermore, as shown in the examples below, the method may be used to produce diorganodihalosilanes, such as Me2SiCl2 with minimal amounts of S1CI4 being produced
EXAMPLES
[0032] These examples are intended to illustrate some embodiments of the invention and should not be interpreted as limiting the scope of the invention set forth in the claims. The comparative examples are non-invention examples. S1O2 was purchased from Fischer Scientific and Sigma Aldrich. Mg and PdCl2 were purchased from Sigma Aldrich.
[0033] Comparative Example A - A sample of S1O2 was ball milled for 30 min to decrease the particle size and increase the surface area. The resulting milled S1O2 was then reacted with H3CCI (MeCI). A peak identified in GC-TCD as MeHSiCl2 was observed in the reactor effluent at an instantaneous maximum 0.15% yield.
[0034] Comparative Example B - Magnesium was ball milled with S1O2 in a 4:1 molar ratio for 1 hour and with S1O2 in a 2:1 ratio for 4 hours. The resulting Mg-Si02 combinations were then reacted with H3CCI (MeCI). The 4:1 Mg:Si02 reaction with H3CCI (MeCI) resulted in very small peaks in the GC-TCD spectra that were identified as MeSiCl3 and Me2SiCl2- The XRD detected MgO, silicon, Mg2SiC>4 and S1O2. The presence of silicon in the material most likely accounts for the chlorosilanes observed in the GC-TCD of the reactor effluent. For the 2:1 Mg :Si02 experiment, no Si products were observed in the GC spectra upon reaction with H3CCI (MeCI). The XRD revealed the presence of MgO, Si and Mg2Si04- Without wishing to be bound by theory, it is thought that the Si was either not accessible and/or had very low activity. The SEM/EDS for the 2:1 Mg:Si02 found the sample to contain primarily oxygen and magnesium, with some silicon and carbon and very little chlorine.
[0035] General Procedure for the Examples - PdCl2 was combined with the ball milled 2:1 Mg:Si02 prepared in Comparative Example B. Several mole ratios of Pd:Si (based on the amount of Si present in Mg-Si02 sample) were tested. The ratios tested were 1 :2.2, 1 :2.5, 1 :3, 1 :4.4, and 1 :6. The Pd:Mg-SiC>2 solids were ball milled for a prolonged period of time prior to placing them in the methylation reactor used in comparatives examples 1 and 2. For each sample, the Pd:Mg-Si02 was treated with H2 at temperatures≥550 °C first and then reacted with H3CCI (MeCI) at 300 °C until the production of methyl chlorosilanes decreased significantly. Then the high temperature H2 treatment was repeated again. Each H2 treatment followed by H3CCI (MeCI) reaction was defined as a cycle. Variable numbers of cycles (usually < 20) were used depending on the initial data and the rate of production of methyl chlorosilanes. [0036] Example 1 - 1 :2.2 Pd:Si molar ratio - In a flow reactor, 0.5 g of 1 :2.2 PdCl2:Mg-Si02 was loaded into a glass tube. The activation was performed with 100 seem H2 at 850 ^ for 2-3 hours. The reaction tube was then cooled to 300 °C while H2 flow continued at 10 seem. Once 300 °C was reached, the H2 was turned off, and the H3CCI (MeCI) feed was started at 1 .86 seem. Samples were taken from the reaction stream and injected into a GC-TCD for analysis using an online switching valve. Total H3CCI (MeCI) reaction time was 2 hours.
[0037] Online GC-TCD analysis provided the production of the chlorosilanes data listed in Table 1 . In some instances, the catalyst was cycled several times. Overall conversion of Si was 2.8%.
Table 1. List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
Figure imgf000010_0001
[0038] Example 2 - 1 :2.5 Pd:Si molar ratio - In a flow reactor, 0.5 g of 1 :2.5 PdCl2:Mg-Si02 was loaded into a glass tube. The activation was performed with 100 seem H2 at 850 ^ for 2-3 hours. The reaction tube was then cooled to 300 °C while H2 flow continued at 10 seem. Once 300 °C was reached, the H2 was turned off, and the
H3CCI (MeCI) feed was started at 1 .86 seem. Samples were taken from the reaction stream and injected into a GC-TCD for analysis using an online switching valve. Total H3CCI (MeCI) reaction time was 2 hours.
[0039] Online GC-TCD analysis provided the production of the chlorosilanes data listed in Table 2. In some instances, the catalyst was cycled several times. Overall conversion of Si was 24%. Table 2. List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
Figure imgf000011_0001
[0040] Example 3 - 1 :3 Pd:Si molar ratio - In a flow reactor, 0.5 g of 1 :3 PdC^Mg- S1O2 was loaded into a glass tube. The Activation was performed with 100 seem H2 at
850 °C for 2-3 hours. The reaction tube was then cooled to 300 <C while H2 flow continued at 10 seem. Once 300 °C was reached, the H2 was turned off, and the H3CCI
(MeCI) feed was started at 1 .86 seem. Samples were taken from the reaction stream and injected into a GC-TCD for analysis using an online switching valve. Total H3CCI (MeCI) reaction time was 2 hours.
[0041] Online GC-TCD analysis provided the production of the chlorosilanes data listed in Table 3. In some instances, the catalyst was cycled several times. Overall conversion of Si was 21 %.
Table 3. List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
Figure imgf000011_0002
[0042] Example 4 - 1 :4.4 Pd:Si molar ratio - In a flow reactor, 0.5 g of 1 :4.4
PdCl2:Mg-Si02 was loaded into a glass tube. The activation was performed with 100 seem H2 at 850 ^ for 2-3 hours. The reaction tube was then cooled to 300 °C while H2 flow continued at 10 seem. Once 300 °C was reached, the H2 was turned off, and the H3CCI (MeCI) feed was started at 1 .86 seem. Samples were taken from the reaction stream and injected into a GC-TCD for analysis using an online switching valve. Total H3CCI (MeCI) reaction time was 2 hours.
[0043] Online GC-TCD analysis provided the production of the chlorosilanes data listed in Table 4. In some instances, the catalyst was cycled several times. Overall conversion of Si was 26%.
Table 4. List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
Figure imgf000012_0001
[0044] Example 5 - 1 :6 Pd:Si molar ratio - Example 4 was repeated, except using 0.5 g of 1 :6 PdCl2:Mg-Si02 (instead of 0.5 g of 1 :4.4 PdCl2:Mg-Si02).
[0045] Online GC-TCD analysis provided the production of the chlorosilanes data listed in Table 5. In some instances, the catalyst was cycled several times. Overall conversion of Si was 21 %.
Table 5. List of chlorosilanes produced in reaction with their respective weight % in the reactor effluent and % selectivity.
Figure imgf000012_0002
[0046] For purposes of this application, the following terms are as defined below. The articles 'a', 'an', and 'the' each refer to one or more, unless otherwise indicated by the context of the specification. [0047] "Alkyl" means an acyclic, branched or unbranched, saturated monovalent hydrocarbon group. Examples of alkyl groups include Me, Et, Pr, 1 -methylethyl, Bu, 1 - methylpropyl, 2-methylpropyl, 1 ,1 -dimethylethyl, 1 -methylbutyl, 1 -ethylpropyl, pentyl, 2- methylbutyl, 3-methylbutyl, 1 ,2-dimethylpropyl, 2,2-dimethylpropyl, hexyl, heptyl, 2- ethylhexyl, octyl, nonyl, and decyl. Alkyl groups have at least one carbon atom.
Alternatively, alkyl groups may have 1 to 12 carbon atoms, alternatively 1 to 10 carbon atoms, alternatively 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, alternatively 1 to 2 carbon atoms, and alternatively 1 carbon atom.
[0048] "Aralkyl" and "alkaryl" each refer to an alkyl group having a pendant and/or terminal aryl group or an aryl group having a pendant alkyl group. Exemplary aralkyl groups include benzyl, tolyl, xylyl, phenylethyl, phenyl propyl, and phenyl butyl. Aralkyl groups have at least 4 carbon atoms. Monocyclic aralkyl groups may have 4 to 12 carbon atoms, alternatively 4 to 9 carbon atoms, and alternatively 4 to 7 carbon atoms. Polycyclic aralkyl groups may have 7 to 17 carbon atoms, alternatively 7 to 14 carbon atoms, and alternatively 9 to 10 carbon atoms.
[0049] "Alkenyl" means an acyclic, branched, or unbranched unsaturated monovalent hydrocarbon group, where the monovalent hydrocarbon group has a double bond.
Alkenyl groups include Vi, allyl, propenyl, and hexenyl. Alkenyl groups have at least 2 carbon atoms. Alternatively, alkenyl groups may have 2 to 12 carbon atoms,
alternatively 2 to 10 carbon atoms, alternatively 2 to 6 carbon atoms, alternatively 2 to 4 carbon atoms, and alternatively 2 carbon atoms.
[0050] "Alkynyl" means an acyclic, branched, or unbranched unsaturated monovalent hydrocarbon group, where the monovalent hydrocarbon group has a triple bond. Alkynyl groups include ethynyl and propynyl. Alkynyl groups have at least 2 carbon atoms. Alternatively, alkynyl groups may have 2 to 12 carbon atoms, alternatively 2 to 10 carbon atoms, alternatively 2 to 6 carbon atoms, alternatively 2 to 4 carbon atoms, and alternatively 2 carbon atoms.
[0051] "Aryl" means a cyclic, fully unsaturated, hydrocarbon group. Aryl is exemplified by, but not limited to, Ph and naphthyl. Aryl groups have at least 5 carbon atoms.
Monocyclic aryl groups may have 6 to 9 carbon atoms, alternatively 6 to 7 carbon atoms, and alternatively 6 carbon atoms. Polycyclic aryl groups may have 10 to 17 carbon atoms, alternatively 10 to 14 carbon atoms, and alternatively 12 to 14 carbon atoms. [0052] "Carbocycle" and "carbocyclic" refer to a hydrocarbon ring. Carbocycles may be monocyclic or alternatively may be fused, bridged, or spiro polycyclic rings.
Carbocycles have at least 3 carbon atoms. Monocyclic carbocycles may have 3 to 9 carbon atoms, alternatively 4 to 7 carbon atoms, and alternatively 5 to 6 carbon atoms. Polycyclic carbocycles may have 7 to 17 carbon atoms, alternatively 7 to 14 carbon atoms, and alternatively 9 to 10 carbon atoms. Carbocycles may be saturated or partially unsaturated.
[0053] "Cycloalkyl" refers to a saturated hydrocarbon group including a saturated carbocycle. Cycloalkyl groups are exemplified by cyclobutyl, cyclopentyl, cyclohexyl, and methylcyclohexyl. Cycloalkyl groups have at least 3 carbon atoms. Monocyclic cycloalkyl groups may have 3 to 9 carbon atoms, alternatively 4 to 7 carbon atoms, and alternatively 5 to 6 carbon atoms. Polycyclic cycloalkyl groups may have 7 to 17 carbon atoms, alternatively 7 to 14 carbon atoms, and alternatively 9 to 10 carbon atoms.
[0054] "Metallic" means that the metal has an oxidation number of zero.
[0055] "Residence time" means the time which a material takes to pass through a reactor system in a continuous process, or the time a material spends in the reactor in a batch process. For example, residence time may refer to the time during which one reactor volume of the reactant makes contact with H2 in step (ii) of the method; or the time during which one reactor volume of the activated reactant makes contact with the organohalide in step (iii) as the reactant or activated reactant passes through the reactor system in a continuous process or during which the reactant or activated reactant is placed within the reactor in a batch process. Alternatively, residence time may refer to the time for one reactor volume of reactant gases to pass through a reactor charged with the reactant or activated reactant, e.g., the time for one reactor volume of the
organohalide to pass through a reactor charged with the activated reactant.
[0056] "Mechanochemically processing" means applying mechanical energy to initiate chemical reactions and/or structural changes. Mechanochemically processing may be performed, for example, by techniques such as milling, e.g., ball milling. Milling may be performed using any convenient milling equipment such as a mixer mill, planetary mill, attritor, or ball mill. Mechanochemical processing may be performed, for example, using the methods and equipment described in, "Mechanical alloying and milling" by C.
Suryanarayana, Progress in Materials Science 46 (2000) 1 -184. [0057] "Spent reactant" refers to the reactant after it has been contacted with the organohalide in step (iii) (or after step (v), when step (v) is present in the method). The spent reactant after step (iii) (or step (v)) is the mass that remained in the reactor when the yield of the organosilane volatile components was reduced to trace amounts. This can be after step (iii) or step (v), when step (v) is present in the method.
[0058] The disclosure of ranges includes the range itself and also anything subsumed therein, as well as endpoints. For example, disclosure of a range of 2.0 to 4.0 includes not only the range of 2.0 to 4.0, but also 2.1 , 2.3, 3.4, 3.5, and 4.0 individually, as well as any other number subsumed in the range. Furthermore, disclosure of a range of, for example, 2.0 to 4.0 includes the subsets of, for example, 2.1 to 3.5, 2.3 to 3.4, 2.6 to 3.7, and 3.8 to 4.0, as well as any other subset subsumed in the range.
[0059] With respect to any Markush groups relied upon herein for describing particular features or aspects of various embodiments, it is to be appreciated that different, special, and/or unexpected results may be obtained from each member of the respective
Markush group independent from all other Markush members. Each member of a Markush group may be relied upon individually and or in combination with any other member or members of the group, and each member provides adequate support for specific embodiments within the scope of the appended claims. For example, disclosure of the Markush group: alkyl, aryl, and carbocyclic includes the member alkyl individually; the subgroup alkyl and aryl; and any other individual member and subgroup subsumed therein.
[0060] It is also to be understood that any ranges and subranges relied upon in describing various embodiments of the present disclosure independently and collectively fall within the scope of the appended claims, and are understood to describe and contemplate all ranges including whole and/or fractional values therein, even if such values are not expressly written herein. The enumerated ranges and subranges sufficiently describe and enable various embodiments of the present disclosure, and such ranges and subranges may be further delineated into relevant halves, thirds, quarters, fifths, and so on. As just one example, a range "of 200 to 1400" may be further delineated into a lower third, i.e., from 200 to 600, a middle third, i.e., from 600 to 1000, and an upper third, i.e., from 1000 to 1400, which individually and collectively are within the scope of the appended claims, and may be relied upon individually and/or collectively and provide adequate support for specific embodiments within the scope of the appended claims. In addition, with respect to the language which defines or modifies a range, such as "at least," "greater than," "less than," "no more than," and the like, it is to be understood that such language includes subranges and/or an upper or lower limit. As another example, a range of "at least 0.1 %" inherently includes a subrange from 0.1 % to 35%, a subrange from 10% to 25%, a subrange from 23% to 30%, and so on, and each subrange may be relied upon individually and/or collectively and provides adequate support for specific embodiments within the scope of the appended claims. Finally, an individual number within a disclosed range may be relied upon and provides adequate support for specific embodiments within the scope of the appended claims. For example, a range of "1 to 9" includes various individual integers, such as 3, as well as individual numbers including a decimal point (or fraction), such as 4.1 , which may be relied upon and provide adequate support for specific embodiments within the scope of the appended claims.
[0061] The subject matter of all combinations of independent and dependent claims, both singly and multiply dependent, is expressly contemplated but is not described in detail for the sake of brevity. The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described.

Claims

CLAIMS:
1 . A method for forming a reaction product comprising a halosilane comprises:
(i) combining ingredients to form a reactant, where the ingredients comprise
(a) Si02,
(b) magnesium, and
(c) a silicide precursor, where ingredient (c) is a metal halide of formula MXa, where M is a metal selected from the group consisting of copper, cobalt, molybdenum, nickel, palladium, platinum, and tungsten; subscript a is 1 to maximum valance of the metal selected for M; and each X is independently a halogen atom; thereby forming the reactant;
(ii) contacting H2 with the reactant to form an activated reactant; and
(iii) contacting an organohalide with the activated reactant to form a spent reactant and the halosilane, where the halosilane has formula RnHmSiX(4-n.m), where subscript n is 0 to 3, subscript m is 0 to 2, a quantity (n + m) < 3, each R is independently a hydrocarbyl group, and X is as defined above,
optionally (iv) contacting H2 with the spent reactant to re-activate the spent reactant, thereby forming a re-activated reactant,
optionally (v) contacting additional organohalide with the re-activated reactant, optionally (vi) repeating steps (iv) and (v) one or more times, and
optionally (vii) repeating step (i) and repeating steps (ii)-(v) one or more times.
2. The method of claim 1 , where
Step (i) is performed at 23 °C to 200 <€, and/or
Step (ii) is performed at 500 <€ to 1000 <€, and/or
Step (iii) is performed at 200 °C to 500 <€, and/or
Step (iv) is present, and step (iv) is performed at 500 'Ό to Ι ΟΟΟ 'Ό, and/or
Step (v) is present, and step (v) is performed at 200 °C to 500 'Ό.
3. The method of claim 1 or claim 2, where
Step (i) is performed for 1 to 4 hours, and/or
Step (ii) is performed for 2 to 3 hours, and/or
Step (iii) is performed for up to 2 hours, and/or Step (iv) is present, and step (iv) is performed for 2 to 3 hours, and/or
Step (v) is present, and step (v) is performed for up to 2 hours.
4. The method of any one of the preceding claims, where steps (iv), (v), and (vi) are present, and steps (iv) and (v) are performed 2 to 15 times.
5. The method of any one of the preceding claims, further comprising (viii) recovering the halosilane.
6. The method of any one of the preceding claims, where R is methyl and X is CI.
7. The method of any one of the preceding claims, where the halosilane comprises dimethyldichlorosilane.
8. The method of any one of the preceding claims, further comprising hydrolyzing the halosilane.
9. A polyorganosiloxane prepared by the method of claim 8.
10. The method of any one of claims 1 to 8, where step (i) is performed by
(I) mechanochemically processing ingredients (a) and (b) to form a combination, and
(II) combining the combination and ingredient (c).
1 1 . The method of claim 10, where step (II) is performed by
(I I A) impregnating the combination with ingredient (c), and/or
(MB) optionally mechanochemically processing the combination and ingredient
(c).
12. The method of claim 10, where step (II) is performed by mechanochemically processing the combination and ingredient (c).
13. A method for preparing a reactant comprises: (1 ) mechanochemically processing ingredients (a) and (b) to form a combination, where
Ingredient (a) is S1O2,
Ingredient (b) is magnesium, and
(2) combining the combination and ingredient (c), where ingredient (c) is a metal halide of formula MXa, where M is a metal selected from the group consisting of copper, cobalt, molybdenum, nickel, palladium, platinum, and tungsten; subscript a is 1 to maximum valance of the metal selected for M; and each X is independently a halogen atom; thereby forming the reactant.
14. The method of claim 13, where ingredient (c) is PdX2-
15. The method of claim 13 or claim 14, where step (2) is performed by
(2A) impregnating the combination with ingredient (c), and/or
(2B) optionally mechanochemically processing the combination and ingredient
(c).
16. The method of claim 15, where step (2) is performed by mechanochemically processing the combination and ingredient (c).
17. A reactant prepared by the method of any one of claims 1 3 to 16.
18. The method of any one of claims 1 -8 or 10-16, where the ingredients (a) and (b) are present in a molar ratio of (b):(a) of 0.25:1 to 4:1 .
19. The method of any one of claims 1 -8 or 10-16, where the ingredients are present in amounts sufficient to provide a molar ratio of M:Si of 1 :2 to 1 :10 based on the amounts of metal atom M from ingredient (c) and the amount of Si from ingredient (a).
PCT/US2014/011754 2013-03-15 2014-01-16 Method for making halosilanes from silica WO2014143402A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5213730A (en) * 1988-10-06 1993-05-25 Benchmark Structural Ceramics Corporation Controlled combustion synthesis process for the production of silicide based composites
WO2012102957A1 (en) * 2011-01-25 2012-08-02 Dow Corning Corporation Method of preparing a diorganodihalosilane

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5213730A (en) * 1988-10-06 1993-05-25 Benchmark Structural Ceramics Corporation Controlled combustion synthesis process for the production of silicide based composites
WO2012102957A1 (en) * 2011-01-25 2012-08-02 Dow Corning Corporation Method of preparing a diorganodihalosilane

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
C. SURYANARAYANA: "Mechanical alloying and milling", PROGRESS IN MATERIALS SCIENCE, vol. 46, 2000, pages 1 - 184

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