WO2014099125A1

WO2014099125A1 - Method for preparing a diorganodihalosilane

Info

Publication number: WO2014099125A1
Application number: PCT/US2013/066075
Authority: WO
Inventors: Aaron COPPERNOLL; Catherine HORNER; Krishna Janmanchi
Original assignee: Dow Corning Corporation
Priority date: 2012-12-19
Filing date: 2013-10-22
Publication date: 2014-06-26

Abstract

A method for preparing a reaction product including a diorganodihalosilane includes steps (i) and (ii). Step (i) is contacting a metal oxide supported copper catalyst with ingredients including ingredient (a) and ingredient (b). Ingredient (a) is H₂, and ingredient (b) a tetrahalosilane of formula SiX₄, where each X is independently halo. Step (i) is performed at a temperature from 200 °C to 1400°C. The product of step (i) is a Si-containing copper catalyst free of promoters. Step (ii) is contacting the Si-containing copper catalyst with an organohalide at a temperature from 100°C to 600 °C. The method forms the reaction product and a spent catalyst. The reaction product may include a diorganodihalosilane of formula R₂SiX₂, where each R is independently a monovalent organic group.

Description

METHOD FOR PREPARING A DIORGANODIHALOSILANE

[0001] Diorganodihalosilanes are hydrolyzed to produce a wide range of

polyorganosiloxanes, which are sold into many different industries. Typically,

diorganodihalosilanes are produced commercially by the Mueller-Rochow Direct Process, which comprises passing an organohalide, such as methyl chloride, over zero-valent silicon in the presence of a copper catalyst and various promoters to produce a mixture of organohalosilanes. Of the organohalosilanes produced in the Direct Process,

dimethyldichlorosilane is the most valuable.

[0002] A typical commercial process to make zero-valent silicon comprises the carbothermic reduction of S1O2 in an electric arc furnace at extremely high temperatures.

Generation of these extreme temperatures requires significant amounts of energy, which adds significant cost to the process of producing zero-valent silicon. Consequently, the use of zero-valent silicon also adds significant costs to the production of

diorganodihalosilanes.

[0003] In addition to the Direct Process, diorganodihalosilanes have been produced by the alkylation of silicon tetrachloride and various methylchlorosilanes by passing the vapors of these chlorosilanes together with an alkyl halide over finely divided aluminum or zinc at elevated temperatures. However, this process results in the production of a large amount of aluminum chloride or zinc chloride, which is costly to dispose of on a commercial scale.

[0004] Dow Corning Corporation recently developed a process in the laboratory to synthesize methylchlorosilanes by 1 ) reacting a catalyst with silicon tetrachloride and hydrogen and 2) reacting the resulting silicon rich catalyst with methyl chloride to make a mixture of methylchlorosilanes including dimethyldichlorosilane. The process uses an activated carbon supported copper catalyst with magnesium and gold promoters.

However, the mechanical properties of activated carbon make it difficult to use in commercial scale fluidization processes and fluidized bed reactors. Furthermore, certain promoters, such as those including gold or other precious metals are expensive and add cost to the process.

[0005] Therefore, there is a need for a more economical method of producing diorganodihalosilanes that avoids the need for zero-valent silicon produced by reducing S1O2 at extremely high temperatures and that does not require the costly disposal of byproducts.

BRIEF SUMMARY OF THE INVENTION

[0006] A method for preparing a reaction product comprises steps (i) and (ii), where: step (i) is contacting a metal oxide supported copper catalyst with ingredients comprising ingredient (a) and ingredient (b), where ingredient (a) is H2, and ingredient (b) is a tetrahalosilane of formula S1X4, where each X is independently halo; at a temperature from

200 °C to 1400°C to form a Si-containing copper catalyst free of promoters; and step (ii) is contacting the Si-containing copper catalyst with an organohalide at a temperature from 100°C to 600 °C; thereby forming the reaction product and a spent catalyst.

DETAILED DESCRIPTION OF THE INVENTION

[0007] 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. The prefix "poly" means more than one. Abbreviations used herein are defined in Table A, below.

Table A - Abbreviations

[0008] 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. Similarly, the disclosure of Markush groups includes the entire group and also any individual members and subgroups subsumed therein. For example, disclosure of the Markush group: alkyl, alkenyl, alkynyl, and carbocyclic groups includes the member alkyl individually; the subgroup alkyl and alkenyl; and any other individual member and subgroup subsumed therein.

[0009] "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.

[0010] "Aralkyi" 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 aralkyi groups include benzyl, tolyl, xylyl, phenylethyl, phenyl propyl, and phenyl butyl. Aralkyi groups have at least 4 carbon atoms. Monocyclic aralkyi groups may have 4 to 12 carbon atoms, alternatively 4 to 9 carbon atoms, and alternatively 4 to 7 carbon atoms. Polycyclic aralkyi groups may have 7 to 17 carbon atoms, alternatively 7 to 14 carbon atoms, and alternatively 9 to 10 carbon atoms.

[0011] "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.

[0012] "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.

[0013] "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.

[0014] "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. [0015] "Cycloalkyl" refers to a saturated hydrocarbon group including a 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.

[0016] "Metallic" means that the metal has an oxidation number of zero.

[0017] "Purging" means to introduce a gas stream to the reactor containing the Si- containing copper catalyst to remove unwanted gaseous or liquid materials.

[0018] "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 in step (i) refers to the time during which one reactor volume of the metal oxide supported copper catalyst makes contact with the H2 and tetrahalosilane as the metal oxide supported copper catalyst passes through the reactor system in a continuous process or during which the metal oxide supported copper catalyst 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 catalyst. (E.g., the time for one reactor volume of H2 and S1X4 in step (i) to pass through a reactor charged with metal oxide supported copper catalyst or the time for one reactor volume of organohalide to pass through a reactor charged with Si-containing copper catalyst in step (ii) of the method described herein.)

[0019] "Spent Si-containing copper catalyst" or "spent catalyst" refers to the Si-containing copper catalyst after it has been contacted with the organohalide in step (ii) (or after step (iv), when step (iv) is present in the method). The spent catalyst after step (ii) (or step (iv)) contains an amount of silicon that is less than the amount of silicon in the Si-containing copper catalyst after step (i) and before beginning step (ii) (or after step (iii) and before beginning step (iv)). Spent catalyst may, or may not, be exhausted, i.e., spent catalyst may contain some silicon that may or may not be reactive with the organohalide.

[0020] The method comprises step (i) and step (ii). Step (i) and step (ii) of the method are conducted separately and consecutively. "Separately" means that step (i) and step (ii) do not overlap or coincide. "Consecutively" means that step (ii) is performed after step (i) in the method; however, additional steps may be performed between step (i) and (ii), as described below. "Separate" refers to either spatially or temporally or both. "Consecutive" refers to temporally (and furthermore occurring in a defined order). [0021 ] Step (i) comprises contacting a metal oxide supported copper catalyst with a mixture comprising H2 gas and a tetrahalosilane of formula S1X4, where each X is independently halo; at a temperature from 200 °C to 1400 °C to form a Si-containing copper catalyst comprising at least 0.1 % of Si. The metal oxide supported copper catalyst used in step (i) includes copper and a metal oxide support. The product of step (i) is a silicon- containing, metal oxide supported, copper catalyst (Si-containing copper catalyst).

[0022] Step (ii) comprises contacting the Si-containing copper catalyst with an organohalide at a temperature from 100 °C to 600 °C. The organohalide may have formula RX, where R is a monovalent organic group and X is a halogen atom. The halogen atom selected for X in the organohalide may be the same as the halogen atom selected for X in the tetrahalosilane used in step (i). Alternatively, the halogen atom selected for X in the organohalide may differ from the halogen atom selected for X in the tetrahalosilane used in step (i). The resulting reaction product comprises a diorganodihalosilane of formula R2S1X2, where each R is independently a monovalent organic group.

[0023] The supported copper catalyst used in step (i) may be prepared by, for example, dissolving and/or dispersing a copper salt, such as cupric chloride or cupric nitrate, in a solvent, such as water or aqueous acid, applying the resulting mixture to a metal oxide support, and reducing the copper salt on the surface of the support. For example, CuCl2 or Cu(NC>3)2 can be dissolved in water or aqueous hydrochloric acid to form a solution.

The solution may be mixed with the support, such as silica or alumina. Excess solution can then be removed, and the resulting supported mixture dried. The copper salt can then be reduced on the support with hydrogen by heating, for example at 400 °C to 600 °C, alternatively 500 °C, to give the supported copper catalyst. The order of addition, reduction and multistep addition of salts and subsequent reduction can also be carried out to prepare the metal oxide supported copper catalyst. A method of making the metal oxide supported copper catalyst is also described in detail in the examples section below. Some of these catalysts are also available commercially.

[0024] Examples of supports that may be used to make the metal oxide supported copper catalyst are metal oxides, i.e., oxides of aluminum, titanium, zirconium , and/or silicon. Alternatively, the support may be selected from silica, alumina, and a combination thereof. Alternatively, the support may be alumina. Without wishing to be bound by theory, it is thought that the method described herein may provide the benefit of improved selectivity toward diorganodihalosilanes as compared to a similar process in which an activated carbon supported copper catalyst is used instead of the metal oxide supported copper catalyst described herein. For example, it is thought that the metal oxide supported copper catalyst herein may provide unexpectedly improved selectivity towards desired Me2SiCl2 in a process using S1CI4 as the tetrahalosilane in step (i). Furthermore, it is thought that such benefits in selectivity may be provided without the use of promoters. The Si-containing copper catalyst may be free of promoters. Alternatively, the Si- containing copper catalyst may be free of one or more of Au, Ca, Co, Cs, Fe, Ir, Mg, Ni, Os, Pd, Pt, Rh, Ru, S, and Sn promoters. Alternatively, the Si-containing copper catalyst may be free of all of Au, Ca, Co, Cs, Fe, Ir, Mg, Ni, Os, Pd, Pt, Rh, Ru, S, and Sn promoters. Alternatively, the Si-containing copper catalyst may be free of Au, Ca, Cs, Mg, S, and Sn. Alternatively, the Si-containing copper catalyst may be free of all of Co, Fe, Ir, Ni, Os, Pd, Pt, Rh, and Ru promoters. Alternatively, the Si-containing copper catalyst may be free of Au and Mg promoters. As used herein, "free of" means the supported copper catalyst contains none of the promoter, or if present, the promoter is present in a form and an amount insufficient to change the selectivity of the process, e.g., to produce a diorganodihalosilane product, such as Me2SiCl2- Furthermore, the metal oxide supports described herein may also provide the benefit of enabling use of the metal oxide supported copper catalyst in commercial scale fluidization processes and fluidized bed equipment due to the metal oxides having mechanical properties better suited to fluidization than the mechanical properties of activated carbon.

[0025] The metal oxide supported copper catalyst may comprise an amount ranging from 0.1 % to less than 100%, alternatively 0.1 % to 50%, and alternatively 0.1 % to 35%, of copper, based on the combined weight of the support and metallic copper present in the metal oxide supported copper catalyst.

[0026] The tetrahalosilane has the formula S1X4, where each X is independently halo, such as chloro, bromo, fluoro, or iodo; alternatively chloro, bromo, or iodo; and alternatively chloro. Examples of the tetrahalosilane include, but are not limited to, silicon tetrachloride, silicon tetrabromide, silicon tetraiodide, and silicon tetrafluoride.

[0027] The reactor for step (i) can be any reactor suitable for the combining of gases and solids. For example, the reactor configuration can be a batch vessel, packed bed, stirred bed, vibrating bed, moving bed, re-circulating beds, or a fluidized bed. Alternatively, the reactor for step (i) may be a fluidized bed. When using re-circulating beds, the metal oxide supported copper catalyst can be circulated from a bed for conducting step (i) to a bed for conducting step (ii). To facilitate reaction, the reactor should have means to control the temperature of the reaction zone. [0028] The temperature at which the H2 and S1X4 are contacted with the metal oxide supported copper catalyst in step (i) may be from 200 °C to 1400°C; alternatively 500 °C to

1400°C; alternatively 600 °C to 1200°C; and alternatively 650 °C to 1 100 °C.

[0029] The pressure at which the H2 and S1X4 are contacted with the metal oxide supported copper catalyst in step (i) 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.

[0030] The mole ratio of H2 to S1X4 contacted with the metal oxide supported copper catalyst in step (i) may range from 10,000:1 to 0.01 :1 , alternatively 100:1 to 1 :1 , alternatively 20:1 to 5:1 , alternatively 20:1 to 4:1 , alternatively 20:1 to 2:1 , alternatively 20:1 to 1 :1 , and alternatively 4:1 to 1 :1 .

[0031] The residence time for the H2 and S1X4 is sufficient for the H2 and S1X4 to contact the metal oxide supported copper catalyst and form the Si-containing copper catalyst. For example, a sufficient residence time for the H2 and S1X4 may be at least 0.01 s, alternatively at least 0.1 s, alternatively 0.1 s to 10 min, alternatively 0.1 s to 1 min, alternatively 0.5 s to 10 s, alternatively 1 min to 3 min, and alternatively 5 s to 10 s. The desired residence time may be achieved by adjusting the flow rate of the H2 and S1X4, or by adjusting the total reactor volume, or by any combination thereof.

[0032] The H2 and S1X4 may be fed to the reactor simultaneously; however, other methods of combining, such as by separate pulses or separate streams, are also envisioned.

[0033] Alternatively, the residence time for the metal oxide supported copper catalyst to be in contact with the H2 and S1X4 in step (i) is typically at least 0.1 min; alternatively at least 0.5 minutes; alternatively 0.1 min to 120 min; alternatively 0.5 min to 9 min;

alternatively 0.5 min to 6 min.

[0034] The metal oxide supported copper catalyst is in a sufficient amount. A sufficient amount of metal oxide supported copper catalyst is enough metal oxide supported copper catalyst to form the Si-containing copper catalyst, described below, when the H2 and S1X4 are contacted with the metal oxide supported copper catalyst. For example, a sufficient amount of metal oxide supported copper catalyst may be at least 0.01 mg catalyst/cm³ of reactor volume; alternatively at least 0.5 mg catalyst/cm³ of reactor volume, and alternatively 1 mg catalyst/cm³ of reactor volume to maximum bulk density of the metal oxide supported copper catalyst, alternatively 1 mg to 5,000 mg catalyst/cm³ of reactor volume, alternatively 1 mg to 1 ,000 mg catalyst/cm³ of reactor volume, and alternatively 1 mg to 900 mg catalyst/cm³ of reactor volume.

[0035] There is no upper limit on the time for which step (i) is conducted. For example, step (i) is usually conducted for at least 0.1 s, alternatively from 1 s to 5 hr, alternatively from 1 min to 1 hr.

[0036] In step (ii) of the method described herein, the Si-containing copper catalyst prepared in step (i) is contacted with an organohalide at a temperature from 100°C to 600 °C to form a reaction product comprising a diorganodihalosilane. The reaction product comprises a diorganodihalosilane of formula R2S1X2, where each R is independently a monovalent organic group, and each X is independently halo, as described above.

[0037] The Si-containing copper catalyst comprises an amount of silicon of at least 0.1 %, alternatively 0.1 % to 90%, alternatively 1 % to 20%, alternatively 1 % to 5%, based on the total weight of Si-containing copper catalyst (including the support). The percentage of silicon in the Si-containing copper catalyst can be determined using standard analytical tests. For example, the percentage of Si may be determined using ICP-AES and ICP-MS.

[0038] The organohalide used in step (ii) may have the formula RX, where R is a monovalent organic group. R may be a hydrocarbyl group. R may be selected from the group consisting of an alkyl group, an aralkyi group, an aryl group, an alkenyl group, an alkynyl group, and a carbocyclic group, as defined above. Alternatively, R may be an alkyl group or a cycloalkyi group. Alternatively, R may be an aryl group or an aralkyi group. X is halo as defined above, and X in the organohalide used in step (ii) may be the same as, or different from, that in the tetrahalosilane used in step (i). 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 cycloalkyi groups for R may have 4 to 1 0 carbon atoms, alternatively 6 to 8 carbon atoms. Alkyl groups containing at least three carbon atoms can have a branched or unbranched structure. 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.

[0039] The reactors suitable for use in step (ii) are as described for step (i). The same reactor may be used for step (i) as used in step (ii). Alternatively, separate reactors may be used for steps (i) and (ii). When separate reactors are used, the type of reactor in each step may be the same or different.

[0040] In step (ii), the organohalide may be contacted with the Si-containing copper catalyst by feeding the organohalide into a reactor containing the Si-containing copper catalyst produced in step (i). [0041] The residence time of the organohalide is sufficient for the organohalide to react with the Si-containing copper catalyst to form the reaction product comprising the diorganodihalosilane in step (ii). For example, a sufficient residence time of the organohalide may be at least 0.01 s, alternatively at least 0.1 s, alternatively 0.5 s to 10 min, alternatively 1 s to 1 min, alternatively 1 s to 10 s. The desired residence time can be achieved by adjusting the flow rate of the organohalide.

[0042] The residence time for the Si-containing copper catalyst to be in contact with the organohalide in step (ii) is typically at least 1 minute; alternatively at least 5 minutes;

alternatively 1 min to 120 min; alternatively 5 min to 90 min; alternatively 5 min to 60 min. Alternatively, there is no upper limit on the residence time for which step (ii) is conducted.

[0043] The temperature at which organohalide is contacted with the Si-containing copper catalyst in step (ii) may be from 100°C to 600 °C, alternatively 200 °C to 500 °C, and alternatively 250 °C to 375 °C.

[0044] Step (ii) is typically conducted until the amount of silicon in the Si-containing copper catalyst falls below a predetermined limit, e.g., until the Si-containing copper catalyst is spent, as described below. For example, step (ii) may be conducted until the amount of silicon in the Si-containing copper catalyst is below 90%, alternatively 1 % to 90%, alternatively 1 % to 40%, of its initial weight percent, based on the total amount of the silicon deposited in step (i). The initial weight percent of silicon in the Si-containing copper catalyst is the weight percent of silicon in the Si-containing copper catalyst before the Si- containing copper catalyst is contacted with the organohalide in step (ii) (or step (iv), described below). The amount of silicon in the Si-containing copper catalyst can be monitored by correlating production of the reaction product of step (ii) with the weight percent of silicon in the Si-containing copper catalyst and then monitoring the reactor effluent or may be determined as described above for the Si-containing copper catalyst .

[0045] The pressure at which the organohalide is contacted with the Si-containing copper catalyst in step (ii) can be sub-atmospheric, atmospheric, or super-atmospheric. For example, the pressure may range from 0 kPag to 2000 kPag; alternatively 100 kPag to 1000 kPag; alternatively 100 kPag to 800 kPag.

[0046] The Si-containing copper catalyst is present in a sufficient amount. A sufficient amount of Si-containing copper catalyst is enough Si-containing copper catalyst to form the diorganodihalosilane, described herein, when the Si-containing copper catalyst is contacted with the organohalide. For example, a sufficient amount of Si-containing copper catalyst may be at least 0.01 mg catalyst/cm³ of reactor volume; alternatively at least 0.5 mg catalyst/cm³ of reactor volume; alternatively 1 mg catalyst/cm³ of reactor volume to maximum bulk density of the Si-containing copper catalyst, alternatively 1 mg to 5,000 mg catalyst/cm³ of reactor volume, alternatively 1 mg to 1 ,000 mg catalyst/cm³ of reactor volume, and alternatively 1 mg to 900 mg catalyst/cm³ of reactor volume.

[0047] The method described herein may optionally further comprise purging. Purging may be performed before contacting the metal oxide supported copper catalyst with H2 and S1X4 in step (i) and/or before contacting the Si-containing copper catalyst with the organohalide in step (ii) and/or before contacting the spent catalyst with H2 and S1X4 in step (iii) and/or before the contacting the Si-containing copper catalyst re-formed in step (iii) with the additional organohalide in step (iv), described below. Alternatively, purging may be performed before contacting the Si-containing copper catalyst with the

organohalide in step (ii) and/or before contacting of the re-formed Si-containing copper catalyst with the organohalide in step (iv), described below. The purging step comprises introducing a gas stream into the reactor containing the catalyst to remove unwanted materials. Unwanted materials in step (ii), and when present step (iv), may include, for example, H2, O2, H2O and HX, where X is halo as defined above. Purging may be accomplished with an inert gas, such as argon or nitrogen, or with a reactive gas, such as the organohalide.

[0048] In step (ii) the Si-containing copper catalyst and the organohalide may be contacted in the absence of H2, in the absence of the tetrahalosilane of formula S1X4, or in the absence of both H2 and S1X4.

[0049] The method may optionally further comprise steps (iii) and (iv) after step (ii). The purpose of steps (iii) and (iv) is to recycle spent catalyst by repeating steps (i) and (ii) using spent catalyst in place of the metal oxide supported copper catalyst used in step (i). The spent catalyst after step (ii) contains an amount of silicon less than the amount of silicon in the Si-containing copper catalyst after step (i) and before beginning step (ii). The spent catalyst left after step (iv) contains an amount of silicon less than the amount of silicon in the re-formed Si-containing copper catalyst produced in step (iii).

[0050] After step (ii), the Si-containing copper catalyst is considered spent because the amount of silicon in the Si-containing copper catalyst is reduced, as compared to the amount of silicon deposited in step (i). This spent catalyst contains less silicon than the Si- containing copper catalyst formed in step (i). For example, the amount of reduction in the amount of silicon deposited in step (i) may be greater than 90%, alternatively greater than 95%, alternatively greater than 99%, and alternatively 99.9%. Alternatively, the amount of the reduction may be 90% to 99.9% of the amount of silicon deposited in step (i).

[0051] Step (iii) comprises contacting the spent catalyst with the mixture comprising H2 and tetrahalosilane, as described for step (i), at a temperature from 200 °C to 1400 °C to re- form the Si-containing copper catalyst comprising at least 0.1 % of Si. The tetrahalosilane used in step (iii) may be more of the same tetrahalosilane used above in step (i).

Alternatively, the tetrahalosilane used in step (iii) may be a tetrahalosilane of formula S1X4, where at least one instance of X is different than that used in the tetrahalosilane of step (i). Step (iv) comprises contacting the re-formed Si-containing copper catalyst produced in step (iii) with the organohalide (as described for step (ii), above) at a temperature from 100°C to 600 °C to form the reaction product comprising the diorganodihalosilane.

[0052] Without wishing to be bound by theory, it is thought that the method described herein allows for maximizing the number of cycles for repeating steps (iii) and (iv). The method may optionally further comprise repeating steps (iii) and (iv) at least 1 time, alternatively from 1 to 10⁵ times, alternatively from 1 to 1 ,000 times, alternatively from 1 to 100 times, and alternatively from 1 to 10 times.

[0053] If the organohalide or tetrahalosilane are liquids at or below standard temperature and pressure, the method may further comprise pre-heating and gasifying the organohalide and/or the tetrahalosilane by known methods before contacting the tetrahalosilane with the metal oxide supported copper catalyst in step (i) and/or step (iii) and/or before contacting the organohalide with the Si-containing copper catalyst in step (ii) and/or step (iv).

Alternatively, the process may further comprise bubbling the hydrogen through liquid tetrahalosilane to vaporize the tetrahalosilane before contacting with the metal oxide supported copper catalyst in step (i) and/or the spent catalyst in step (iii).

[0054] If the organohalide or the tetrahalosilane are solids at or below standard temperature and pressure, the method may further comprise pre-heating above the melting points and liquefying or vaporizing the tetrahalosilane prior to bringing it in contact with the metal oxide supported copper catalyst in step (i) and/or the spent catalyst in step (iii).

[0055] The method may optionally further comprise step (v). Step (v) comprises recovering the reaction product produced (i.e., product of step (ii) and/or step (iv)). The reaction product comprises an organosilane. The organosilane 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 and exemplified herein comprises an organosilane of formula RbHcSiX(4-b-c)> ^wnere R ^ar|d X are as defined and exemplified above for the organohalide; subscript b is 1 , 2, 3, or 4, alternatively b is 1 or 2; subscript c is 0, 1 , or 2, alternatively 0 or 1 ; alternatively 0; and a quantity (b + c) is 1 , 2, 3, or 4.

[0056] Alternatively, the reaction product may comprise organohalosilanes (where subscript b is 1 , 2, or 3, and the quantity (b + c) is 1 , 2, or 3. Exemplary organohalosilanes 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., Ch^SiC^), methyltribromosilane (i.e., CH^S r^), and methyldichlorosilane (CH₃(H)SiCI₂).

[0057] A hydrogen halide may be present in the reaction product produced according the present method. The hydrogen halide has formula HX, where X is as defined above. The hydrogen halide may be separated from the diorganodihalosilane via condensation, distillation, or other means and collected or fed to other chemical processes.

[0058] The method described herein produces organosilanes, particularly

organohalosilanes such as diorganodihalosilanes. Diorganodihalosilanes can be hydrolyzed in known processes for producing polydiorganosiloxanes. The

polydiorganosiloxanes thus produced find use in many industries and applications.

[0059] The method described herein may offer the advantage of not producing large amounts of metal halide byproducts requiring costly disposal. Still further, the method may have good selectivity to produce diorganodihalosilanes, as compared to other

organosilanes. Finally, the Si-containing copper catalyst may be re-formed and reused in the method, and the re-forming and reuse may provide increasing diorganodihalosilane production and/or selectivity.

EXAMPLES

[0060] 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.

[0061 ] The reaction apparatus used in these examples comprised a 4.8 mm inner diameter quartz glass tube in a flow reactor. The reactor tube was heated using a

Lindberg/Blue Minimite 2.54 cm tube furnace. Brooks instrument 5850 mass flow controllers were used to control gas flow rates. A stainless steel SiCl4 bubbler was used to introduce S1CI4 into the H2 gas stream. The amount of SiCl4 in the H2 gas stream was adjusted by changing the temperature of the S1CI4 in the bubbler according to calculations using well-known thermodynamic principles. The reactor effluent passed through an actuated 6-way valve from Vici. When actuated, the 6-way valve would make a100 uL injection effluent gases from the reactor onto a GC/GC-MS made by Agilent to characterize the reaction products. [0062] In example 1 , methylchlorosilanes were produced over an alumina supported copper catalyst treated with H2 and SiCU. First, 7.0 grams of alumina (DAVICAT AL2720) were impregnated with 6.3474 grams of CuCl2 (ALDRICH 451665) taken in 30 ml_ aqueous HCI. The resultant mixture was placed on a hot plate to remove excess solvent. The resulting material was further dried in hot air oven at 200 °C for 12 hours to form an alumina supported copper catalyst.

[0063] The alumina supported copper catalyst prepared as described above was placed in a fixed bed reactor. This alumina supported copper catalyst was exposed to 100 seem H2 at 500 °C for 3-4 hours. After this, the resulting activated alumina supported copper catalyst was exposed to gaseous S1CI4 in H2 for 30 min at 750 °C by bubbling H2 through a stainless steel S1CI4 bubbler. The total flow of H2 and S1CI4 was 150 seem, with the mole ratio of H2 to S1CI4 of 4:1 . The S1CI4 flow was controlled by the H2 flow by keeping the bubbler temperature at 14.6°C. The resulting Si-containing copper catalyst comprised 33wt% Si. After 30 minutes, the S1CI4 flow was ceased and a hydrogen flow of 100 seem was maintained while cooling to 300 °C over a period of 1 hour.

[0064] When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, a temperature of 300 °C and atmospheric pressure for 60 min. The reaction was periodically sampled and analyzed by GC to determine the weight percent of (CH^SiC^ and other chlorosilanes based on the total mass leaving the reactor.

[0065] Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H2 at 500 °C for 30-60 min and contacted again with H2/S1CI4, to re-form the Si-containing copper catalyst, for 30 min at 750 °C. The combined flow rate of H2 and

S1CI4 was 150 seem, and the mole ratio of H2 to S1CI4 was 4:1 . After the Si-containing copper catalyst was re-formed, the reactor was again purged with argon, and CH3CI was contacted with the re-formed Si-contained copper catalyst as described above. The cycle {i.e., of steps (iii) and (iv)) was repeated 6 times, resulting in 7 cycles. The results are shown in Table 1 . This example demonstrates that the reaction product of the method described in this example is a mixture of methylchlorosilanes with dimethyldichlorosilane being the major product. Table 1

[0066] 'N/A' means the value was not measured. This example shows that under the conditions tested, selectivity toward Me2SiCl2 stays constant or improves as the number of cycles increases.

[0067] In example 2, 7.0 grams of alumina (DAVICAT AL2720) was impregnated with

10.9805 grams of Cu(N03)2-2.5H₂0 (ALDRICH 12837) taken in 30ml de-ionized water.

The resultant mixture was placed on a hot plate to remove excess solvent. The resulting material was further dried in hot air oven at 200 °C for 12 hours. The resulting material was an alumina supported copper catalyst.

[0068] The activity of this alumina supported copper catalyst was evaluated in a fixed bed reactor in gas phase. The alumina supported copper catalyst (0.5 g) was placed in the fixed bed reactor and reduced by feeding H2 at 500 °C and 100 seem through the reactor for 3-4 hours. After this, a mixture of H2 and S1CI4 was fed through the reactor for 30 min at 750 °C by bubbling H2 through a stainless steel SiCl4 bubbler. The total flow of H2 and

SiCl4 was 150 seem, and the mole ratio of H2 to SiCl4 was 4:1 . The S1CI4 flow was controlled by H2 flow by keeping the bubbler temperature at 14.6°C. The gas and vapor leaving the bubbler was fed into the reactor containing the alumina supported copper catalyst to form a Si-containing copper catalyst compromising 33wt% Si. After 30 minutes, the S1CI4 flow was ceased and a H2 flow of 100 seem was maintained while cooling to 300 °C over a period of 1 hour.

[0069] When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, a temperature of 300 °C and atmospheric pressure for 60 min. The reactor effluent was periodically sampled and analyzed by GC to determine the weight percent of (CH3)2SiCl2 and other chlorosilanes based on the total mass leaving the reactor.

[0070] Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H2 at 500 °C for 30-60 min and contacted again with H2/SiCl4 for 30 min at 750 °C to re-form the Si-containing copper catalyst. The combined flow rate of H2 and

SiCl4 was 150 seem, and the mole ratio of H2 to SiCl4 was 4:1 . After the Si-containing copper catalyst was re-formed, the reactor was again purged with argon, and CH3CI was contacted with the re-formed Si-contained copper catalyst as described above. This cycle was repeated 10 times. The results are shown in Table 2. This example demonstrates that the reaction product prepared under these conditions is a mixture of chlorosilanes with high selectivity towards dimethyldichlorosilane.

Table 2:

[0071] In example 3, an alumina supported copper catalyst with a composition of 30wt% CU/AI2O3 was synthesized using multiple impregnations of Cu(N03)2 on 70 micron size alumina (Sud Chemie T2610) and finally calcining in air at 700°C. The activity of this alumina supported copper catalyst was evaluated in a fixed bed reactor in gas phase. This alumina supported copper catalyst (1 .5 g) was placed in a fixed bed reactor. The alumina supported copper catalyst was reduced under 100 seem of H2 at 500 °C for 3-4 hours.

[0072] Next, a gaseous mixture of H2 and S1CI4 was fed to the reactor for 30 min at

750 °C by bubbling H2 through a stainless steel SiCl4 bubbler. The total flow of H2 and

S1CI4 was 150 seem with the mole ratio of H2 to SiCl4 = 4:1 . The S1CI4 flow was controlled by H2 flow by keeping the bubbler temperature at 14.6°C. The gas and vapor leaving the bubbler was fed into the reactor containing the alumina supported copper catalyst to form a Si-containing copper catalyst compromising about 15wt% Si. After 30 minutes, the S1CI4 flow was ceased, and a H2 flow of 100 seem was maintained while cooling to 300 °C over a period of 1 hour.

[0073] When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, at a temperature of 300 °C and atmospheric pressure for 60 min. The reactor effluent was periodically sampled and analyzed by GC to determine the weight percent of (Ch^SiC^ and other chlorosilanes based on the total mass of the reaction product leaving the reactor.

[0074] Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H2 at 500 °C for 30-60 min and contacted again with H2/SiCl4 for 30 min at 750 °C to re-form the Si containing copper catalyst. The combined flow rate of H2 and

S1CI4 was 150 seem, and the mole ratio of H2 to SiCl4 was 4:1 . After the Si-containing copper catalyst was re-formed, the reactor was purged with argon, and CH3CI was contacted with the re-formed Si-contained copper catalyst as described above. This cycle was repeated 13 times. The results are shown in Table 3. The example demonstrates that the method described in this example 3 produces a reaction product comprising a mixture of methylchlorosilanes with high Si conversions.

Table 3

[0075] In example 4, 0.8 g of an alumina supported copper catalyst, prepared by incipient wetness impregnation, was reduced under 100 seem of H2 at 500 °C for 3-4 hours, then treated in H2/S1CI4 at 750 °C by bubbling H2 through a stainless steel SiCl4 bubbler at 14.6°C. The total flow of H2 and S1CI4 was 150 seem, and the mole ratio of H2 to SiCl4 was 4:1 . The reaction time was varied from 1 min to 30 min. The gas and vapor leaving the bubbler was fed into the reactor containing the alumina supported copper catalyst to form a Si-containing copper catalyst. The amount of Si deposited on the catalyst ranged from 1wt% to 25wt% based on the total weight of the Si-containing copper catalyst depending on the reaction time. After step (i), the S1CI4 flow was ceased and a H2 flow of

100 seem was maintained while cooling to 300 °C over a period of 1 hour.

[0076] When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, a temperature of 300 °C and atmospheric pressure. The reactor effluent was periodically sampled and analyzed by GC to determine the weight percent (CH3)2SiCl2, based on the total mass of reaction product leaving the reactor.

[0077] Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H₂ at 500 °C for 30-60 min and contacted again with H₂/SiCl4 at 750 °C to re-form the Si-containing copper catalyst. The combined flow rate of H2 and SiCl4 was

150 seem, and the mole ratio of H2 to S1CI4 was 4:1 . After the Si-containing copper catalyst was re-formed, the reactor was again purged with argon, and CH3CI was contacted with the re-formed Si-containing copper catalyst as described above. This cycle was repeated 24 times. The results are shown in Table 4. This example demonstrates that in the reaction product under the example 4 conditions, dimethyldichlorosilane is produced by the method described herein.

Table 4: Production of methylchlorosilanes over copper catalyst treated at 750 °C with H2/SiCl4 at different reaction times

[0078] In example 5, a silica supported copper catalyst was prepared by impregnating

7.0 g of silica gel (Sud Chemie D100) with 1 1 .0 g of Cu(N0₃)2-2.5H₂0 (ALDRICH 12837) taken in 30 ml_ de-ionized water. The resulting mixture was placed on a hot plate to remove excess solvent and then further dried in hot air oven at 200 °C for 12 hours.

[0079] The activity of this silica supported copper catalyst was evaluated in a fixed bed reactor in gaseous phase. The silica supported copper catalyst (0.75 g) was placed in the reactor and reduced under 100 seem H2 at 500 °C for 3-4 hours. After this, a mixture of H2 and SiCl4 was fed into the reactor for 30 min at 750 °C by bubbling H2 through a stainless steel S1CI4 bubbler. The total flow of H2 and SiCl4 was 150 seem with the mole ratio of H2 to S1CI4 of 4:1 . The S1CI4 flow was controlled by H2 flow by keeping the bubbler temperature at 14.6°C. The gas and vapor leaving the bubbler was fed into the reactor containing the silica supported copper catalyst to form a Si-containing copper catalyst compromising 21wt% Si. After 30 minutes, the S1CI4 flow was ceased and a H2 flow of

100 seem was maintained while cooling to 300 °C over a period of 1 hour.

[0080] When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, at a temperature of 300 °C and atmospheric pressure for 60 min. The reactor effluent was periodically sampled and analyzed by gas chromatography to determine the weight percent of (Ch^SiC^ and other chlorosilanes based on the total mass leaving the reactor.

[0081 ] Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H2 at 500 °C for 30-60 min and contacted again with H2/SiCl4 for 30 min at 750 °C to re-form the Si-containing copper catalyst. The combined flow rate of H2 and

S1CI4 was 150 seem , and the mole ratio of H2 to S1CI4 was 4:1 . After the Si-containing copper catalyst was re-formed, the reactor was again purged with argon, and CH3CI was contacted with the re-formed Si-contained copper catalyst, as described above. This cycle was repeated 9 times. The results are shown in Table 5. The example demonstrates that the reaction product produced by the method under the conditions in this example 5 comprises mixture of methylchlorosilanes with dimethyldichlorosilane being the major product.

Table 5: Production of methylchlorosilanes over silica supported copper catalyst

[0082] In example 6, 0.75 g of a silica supported copper catalyst, prepared by incipient wetness impregnation, was reduced under 100 seem of H2 at 500 °C for 3-4 hours, then treated in H2/SiCl4 by bubbling H2 through a stainless steel SiCl4 bubbler at 37.2 °C. The total flow of H2 and S1CI4 was 150 seem, and the mole ratio of H2 to S1CI4 was 1 :1 . The reaction temperature was varied from 500 °C to 750 °C. The gas and vapor leaving the bubbler was fed into the reactor containing the silica supported copper catalyst to form a Si-containing copper catalyst. The amount of silicon deposited on the silica supported copper catalyst ranged from 40-70% (w/w) depending on the reaction temperature. After step (i), the S1CI4 flow was ceased and a H2 flow of 100 seem was maintained while cooling to 300 °C over a period of 1 hour.

[0083] When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, at a temperature of 300 °C and atmospheric pressure. The reactor effluent was periodically sampled and analyzed by GC to determine the weight percent (CH3)2SiCl2, based on the total mass leaving the reactor.

[0084] Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H2 at 500 °C for 30 min to 60 min and contacted again with H2/ SiCl4, to re-form the Si- containing copper catalyst at 750 °C. The combined flow rate of H2 and

SiCl4 was 150 seem, and the mole ratio of H2 to SiCl4 was 1 :1 . After the Si-containing copper catalyst was re-formed, the reactor was purged again with argon, and CH3CI was contacted with the re-formed Si-contained copper catalyst as described above. The cycle was repeated 25 times. The results are shown in Table 6. The example demonstrates that dimethyldichlorosilane is produced by the method of the invention and the selectivity of dimethyldichlorosilane is increased with increase in step (i) reaction temperature with H2 and S1CI4.

Table 6: Production of methylchlorosilanes over copper catalyst treated with H2/SiCl4 for

30 min at different reaction temperatures

Cycle Step (i) Si Si Si Me₂SiCI₂ MeSiCI₃ Others (#) temp deposited removed conversion selectivity selectivity selectivity

(°C) (mg) (mg) (%) (%) (%) (%)

1 500 N/A N/A N/A N/A N/A N/A

2 500 388 7 1 .8 62 10 28

3 600 398 5 1 .3 25 28 47

4 750 418 47 1 1 .1 80 12 8

5 600 395 8 2.1 30 17 54

6 500 391 10 2.5 4 6 90

7 750 437 36 8.2 73 14 13

8 700 436 29 6.6 51 20 29

9 500 402 4 0.9 6 1 1 83

10 750 372 19 5.1 68 20 12

1 1 500 397 4 0.9 28 19 53

12 700 450 13 3.0 62 24 14

13 750 N/A 25 N/A 58 14 28

14 750 535 1 1 2.0 51 29 20

15 600 413 13 3.1 1 3 96 Cycle Step (i) Si Si Si Me₂SiCI₂ MeSiCI₃ Others (#) temp deposited removed conversion selectivity selectivity selectivity

(°C) (mg) (mg) (%) (%) (%) (%)

16 600 396 6 1 .6 7 12 81

17 550 396 4 1 .0 20 13 67

18 650 402 9 2.2 43 30 27

19 650 401 8 2.1 23 25 52

20 550 398 6 1 .4 9 17 74

21 650 403 14 3.4 40 27 33

22 700 N/A 26 N/A 68 19 13

23 550 403 6 1 .4 8 12 81

24 700 451 31 6.9 63 16 22

25 650 418 8 1 .8 21 1 1 69

26 550 400 2 0.5 3 20 77

[0085] In example 7, a silica supported copper catalyst was prepared by spray drying. The spray dried 65wt% CuO/Si02 catalyst (5mm extrudates) was obtained from Sud

Chemie and sieved to 1 mm particles.

[0086] The activity of this silica supported copper catalyst was evaluated in a fixed bed reactor in the gaseous phase. The silica supported copper catalyst (1 .5 g) was reduced under 100 seem H2 at 500 °C for 3-4 hours. After this, a mixture of H2 and S1CI4 was fed into the reactor for 30 min at 750 °C by bubbling H2 through a stainless steel S1CI4 bubbler.

The total flow of H2 and S1CI4 was 150 seem with the mole ratio of H2 to S1CI4 of 4:1 . The

S1CI4 flow was controlled by H2 flow by keeping the bubbler temperature at 14.6°C. The gas and vapor leaving the bubbler was fed into the reactor containing the silica supported copper catalyst to form a Si-containing copper catalyst compromising 17wt% silicon. After 30 minutes, the S1CI4 flow was ceased, and a H2 flow of 100 seem was maintained while cooling to 300 °C over a period of 1 hour. When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, a temperature of

300 °C and atmospheric pressure for 60 min to 120 min. The reactor effluent was periodically sampled and analyzed by GC to determine the weight percent of (CH3)2SiCl2 and other chlorosilanes based on the total mass leaving the reactor.

[0087] Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H2 at 500 °C for 30 min to 60 min and contacted again with H2/SiCl4 for

30 min at 750 °C to re-form the Si-containing copper catalyst. The combined flow rate of H2 and S1CI4 was 150 seem, and the mole ratio of H2 to SiCl4 was 4:1 . After the Si- containing copper catalyst was re-formed, the reactor was again purged with argon, and CH3CI was contacted with the re-formed Si-containing copper catalyst as described above.

This cycle was repeated 13 times. The results are shown in Table 7. This example demonstrates that the reaction product containing methylchlorosilanes is produced by the method with high Si conversions and high dimethyldichlorosilane selectivity.

Table 7: Production of methylchlorosilanes over silica supported copper catalyst (spray dried) treated at 750 °C with H₂/SiCI₄ = 4 in step (i) and CH3CI at 300 °C in step (ii)

[0088] In example 8, a silica supported copper catalyst was prepared by spray drying. The spray dried 65wt% CuO/Si02 catalyst had a particle size of 70 urn.

[0089] The activity of this silica supported copper catalyst was evaluated in a fixed bed reactor in the gaseous phase. The silica supported copper catalyst (1 .5 g) was reduced under 100 seem H2 at 500 °C for 3-4 hours. After this, a mixture of H2 and S1CI4 was fed into the reactor for 30 min at 750 °C by bubbling H2 through a stainless steel S1CI4 bubbler.

The total flow of H2 and S1CI4 was 150 seem with the mole ratio of H2 to S1CI4 of 1 :1 . The

S1CI4 flow was controlled by H2 flow by keeping the bubbler temperature at 37.2 °C. The gas and vapor leaving the bubbler was fed into the reactor containing the silica supported copper catalyst to form a Si-containing copper catalyst compromising 50wt% silicon. After 30 minutes, the S1CI4 flow was ceased and a H2 flow of 100 seem was maintained while cooling to 300 °C over a period of 1 hour. When the reactor reached 300 °C, H2 was purged from the reactor with an argon flow of 50 seem for 30 min. [0090] After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem, a temperature of 300 °C and atmospheric pressure for 90 min. The reactor effluent was periodically sampled and analyzed by GC to determine the weight percent of (CH3)2SiCl2 and other chlorosilanes based on the total mass leaving the reactor. Next, the CH3CI feed was ceased, and the spent Si-containing copper catalyst was treated with H2 at 500 °C for 30 min to 60 min and contacted again with H2/SiCl4 for

30 min at 750 °C to re-form the Si-containing copper catalyst. The combined flow rate of H2 and SiCl4 was 150 seem, and the mole ratio of H2 to S1CI4 was 1 :1 .

[0091] After the Si-containing copper catalyst was re-formed, the reactor was again purged with argon, and CH3CI was contacted with the re-formed Si-containing copper catalyst as described above. The cycle was repeated 7 times. The results are shown in Table 8. This example demonstrates that the reaction product including

methylchlorosilanes is produced by the method with high Si conversions and high dimethyldichlorosilane selectivity.

Table 8: Production of methylchlorosilanes over silica supported copper catalyst (70 microns) treated at 750 °C with H₂/SiCI₄ = 1 in step (i) and CH3CI at 300 °C in step (ii)

[0092] In example 9, an alumina supported copper catalyst was prepared as in example 3. This alumina supported copper catalyst had a median particle size of 75 um, and 50 kg was loaded in to a 14 inch inner diameter Inconel 600 fluidized bed reactor with 30 inch freeboard height and a sintered metal filter at the disengagement section (36 inch height). The catalyst was reduced under 50 % nitrogen and 50% hydrogen (3.2 scfm N2 and 3.2 scfm H2) flowing through screw plate distributor at 467 °C for 2 hours. The reactor had a provision to feed separate S1CI4 flow entering through a sparger situated just above the screw plate distributor. The SiCl4 inlet line was preheated before feeding to the reactor, and the line was from the top head of the reactor. Five multi-probe thermocouples were connected inside the reactor at the heights of 1 inch, 5 inches, 13 inches, 25 inches and 37 inches from the distributor. After the reduction, the reactor temperature was raised to 750 °C under N2/H2 gas flow. Next, the N2 flow was ceased, and the alumina supported copper catalyst was treated with SiCl4 and H2 for 25 min to form a Si-containing copper catalyst comprising 0.5 wt% Si in Cu. The total flow of H2 and SiCl4 was 13 scfm with the mole ratio of H2 to S1CI4 of 4:1 . The un-reacted S1CI4 passed through a condenser followed by a gas-liquid separator (both were in dry-ice baths). The uncondensed gas was vented through a scrubber followed by a burner. The outlet lines of the reactor were at ambient temperature starting from the top of reactor bed. The S1CI4 feed rate was controlled by stoke length of the diaphragm pump, which was confirmed by the weight loss of the feed tank. The example demonstrates that the catalyst can be used in a fluidized bed reactor to be able to deposit silicon.

[0093] In example 10, a silica supported copper catalyst was prepared as in example 8, and 14 kg was loaded in to a 14 inch inner diameter Inconel 600 fluidized bed reactor with 30 inch freeboard height and a sintered metal filter at the disengagement section (36 inch height). This silica supported copper catalyst was reduced under 50vol% N2 and 50vol%

H2 (3.2 scfm N2 and 3.2 scfm H2) flowing through the screw plate distributor at 467 °C for 2 hours. The reactor had a provision to feed separate SiCl4 flow entering through the sparger situated just above the screw plate distributor. The SiCl4 line was preheated before feeding to the reactor, and the line was from the top head of the reactor. Five multi-probe thermocouples were connected inside the reactor at the heights of 1 inch, 5 inches, 13 inches, 25 inches and 37 inches from the distributor. After the reduction, the reactor temperature was raised to 750 °C under N2/H2 gas flow. Next, the N2 flow was ceased and the catalyst was treated with S1CI4 and H2 for 2 hours to form a Si-containing copper catalyst comprising 8wt% Si in Cu. The total flow of H2 and S1CI4 was 13 scfm with the mole ratio of H2 to S1CI4 of 4:1 . The un-reacted S1CI4 passed through the condenser followed by a gas-liquid separator (both were in dry-ice baths). The uncondensed gas was vented through a scrubber followed by a burner. The outlet lines of the reactor were at ambient temperature starting from the top of reactor bed. The S1CI4 feed rate was controlled by stoke length of the diaphragm pump, which was confirmed by the weight loss of the feed tank. The Si-containing copper catalyst (1 g) was loaded into a 3/16 inch quartz reactor, which was connected inside a 3/8 inch fixed bed Inconel reactor and heated to 300 °C with an argon flow of 50 seem for 30 min. After 30 min, the argon flow was ceased, and CH3CI was fed through the reactor at a flow rate of 5 seem and atmospheric pressure for 60 min. The reactor effluent was periodically sampled and analyzed by GC to determine the weight percent of chlorosilanes and found to produce 60wt% selectivity towards dimethyldichlorosilane. This example demonstrates that the silica supported copper catalyst can be used in a fluidized bed reactor for silicon deposition to be able to produce methylchlorosilanes by reacting with methyl chloride.

[0094] 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 and provides adequate support for specific embodiments within the scope of the appended claims.

[0095] 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. [0096] 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 preparing a reaction product comprises steps (i) and (ii), where:

step (i) is contacting a metal oxide supported copper catalyst with ingredients comprising ingredient (a) and ingredient (b), where

ingredient (a) is H2, and

ingredient (b) is a tetrahalosilane of formula S1X4, where each X is independently halo,

at a temperature from 200 °C to 1400°C to form a Si-containing copper catalyst free of promoters; and

step (ii) is contacting the Si-containing copper catalyst with an organohalide at a temperature from 100^<€ to 600 °C;

thereby forming the reaction product and a spent catalyst; and

where the method optionally further comprises separate and consecutive steps (iii) and (iv), where steps (iii) and (iv) are performed after step (ii), and where

step (iii) is repeating step (i) using additional H2 and S1X4 and recycling the spent catalyst to re-form the Si-containing copper catalyst, and

step (iv) is repeating step (ii) using the Si-containing copper catalyst re-formed in step (iii) and additional organohalide; and

where the method optionally further comprises step (v), where

step (v) is repeating steps (iii) and (iv) at least one time.

2. The method of claim 1 , where the metal oxide supported copper catalyst used in step (i) is a selected from a silica supported copper catalyst and an alumina supported copper catalyst.

3. The method of claim 1 or claim 2, further comprising purging

before contacting the metal oxide supported copper catalyst with H2 and S1X4 in step (i) and/or

before contacting the Si-containing copper catalyst with the organohalide in step (ii) and/or

before contacting the spent catalyst with H2 and S1X4 in step (iii) and/or before the contacting the Si-containing copper catalyst re-formed in step (iii) with the additional organohalide in step (iv).

4. The method of any one of claims 1 -3, where mole ratio of H2 to S1X4 ranges from 20:1 to 1 :1 .

5. The method of any one of claims 1 -4, where the organohalide has formula RX, where R is a hydrocarbyl group.

6. The method of claim 5, where R is alkyl and X is CI.

7. The method of any one of claims 1 -6, where the contacting in step (ii) is performed in the absence of hydrogen.

8. The method of any one of claims 1 -7, where the reaction product comprises an organosilane of formula Rb^HcSiX(4-b-c) where each R is independently hydrocarbyl;

subscript b is 1 , 2, 3, or 4; and subscript c is 0, 1 , or 2; and a quantity (b + c) is 1 , 2, 3, or 4.

9. The method of claim 8, where the organosilane comprises a diorganodihalosilane of formula R2S1X2, where R is alkyl or aryl; and X is CI, Br, or I.

10. The method of claim 9, where R is methyl and X is CI.

11 . The method of any one of claims 1 -10, further comprising recovering the reaction product.

12. The method of any one of the preceding claims, where one or more of steps (i), (ii), (iii), and/or step (iv) is performed in a fluidized bed reactor.

13. A diorganodihalosilane prepared by the method of any one of the preceding claims.

14. A method comprising hydrolyzing the diorganodihalosilane of claim 13.

15. A polydiorganosiloxane prepared by the method of claim 14.