Catalytic Conversion of Direct Process High-Boiling Component To

Patentamt |||| ||| 1 1|| ||| ||| ||| || || || || ||| |||| || JEuropaischesJ European Patent Office

Office europeen des brevets (11) EP 0 635 510 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int. CI.6: C07F 7/1 2, C07F7/16 of the grant of the patent: 24.02.1999 Bulletin 1999/08

(21) Application number: 94304886.8

(22) Date of filing: 04.07.1994

(54) Catalytic conversion of direct process high-boiling component to chlorosilane monomers in the presence of hydrogen chloride Katalytische Umsetzung von hochsiedenden RLickstanden der Direktsynthese in Chlorosilanmonomere in Gegenwart von Chlorwasserstoff Conversion catalytique du residu a point d'ebullition eleve obtenu par le procede direct en chlorosilanes monomeres en presence de chlorure d'hydrogene

(84) Designated Contracting States: • Dhaul, Ajay Kumar DE FR GB Carrollton, Kentucky (US) • Johnson, Richard Gordon (30) Priority: 19.07.1993 US 94593 Hanover, Indiana (US)

(43) Date of publication of application: (74) Representative: 25.01.1995 Bulletin 1995/04 Spott, Gottfried, Dr. et al Patentanwalte (73) Proprietor: Spott, Weinmiller & Partner DOW CORNING CORPORATION Sendlinger-Tor-Platz 11 Midland, Michigan 48686-0994 (US) 80336 Munchen (DE)

(72) Inventors: (56) References cited: • Chadwick, Kirk Michael EP-A- 0 082 969 EP-A-0155 626 Penarth, South Glamorgan (GB) EP-A- 0 537 740 EP-A- 0 564 109 • Halm, Roland Lee EP-A- 0 574 912 EP-A- 0 634 417 Madison, Indiana (US) FR-A- 1 093 399 US-A- 2 709 176 US-A- 3 432 537

CO o LO LO CO Note: Within nine months from the publication of the mention of the grant of the European patent, give CO any person may notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in o a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. Q_ 99(1) European Patent Convention). LU Printed by Xerox (UK) Business Services 2.16.7/3.6 1 EP 0 635 510 B1 2

Description in a reactor and have a long life in said process. [0007] Our process may be run in any standard type [0001 ] The present invention is a process for convert- reactor for contacting silanes and hydrogen chloride. ing a high-boiling component, resulting from the reac- The process may be run as a batch process, semi-con- tion of an organochloride with silicon, into more 5 tinuous or continuous process. The process can be run, commercially desirable monosilanes. The process com- for example, in a fixed-bed reactor, a stirred-bed reactor prises contacting the high-boiling component with or a f luidized-bed reactor. Preferred is when the process hydrogen chloride at a temperature within a range of is run as a continuous process in a fluidized-bed reac- 250°C. to 1 000°C. in the presence of a catalyst selected tor. from platinum supported on alumina, zeolite, AICI3 and 10 [0008] This present process is useful for converting a AICI3 supported on a support selected from carbon, alu- high-boiling component resulting from the reaction of an mina and silica. organochloride with silicon to form monosilanes. The [0002] The high-boiling component useful in our proc- term "high-boiling component" refers to those materials ess results from a process typically referred to as the with a boiling point above that of the diorganodichlorosi- "Direct Process," where an organohalide is reacted with is lane formed by the reaction of the organochloride with silicon in the presence of a suitable catalyst to form silicon. For example when methyl chloride is reacted monosilanes. The Direct Process is described more with silicon, the diorganodichlorosilane will be dimethyl- fully in US-A 2,380,995 and US-A 2,488,487. It is the dichlorosilane and the high-boiling component will com- main commercial process by which organohalosilanes prise those materials having a boiling point greater than (i.e. monosilanes), for example dimethyldichlorosilane 20 that of dimethyldichlorosilane, i.e. greater than 70°C. and trimethylchlorosilane, are formed. These organoha- [0009] In a typical process for reacting an organochlo- losilanes are reactive compounds which can undergo ride with silicon, the reaction is conducted at a tempera- numerous reactions to form a variety of useful silicon ture of 270°C. to 350°C., in the presence of a suitable containing compounds and polymers. A major commer- catalyst. Gaseous product and unreacted feed are con- cial use of organohalosilanes is in the production of 25 tinuously removed from the process. The removed gas- polysiloxane polymers which are useful as heat transfer eous product and unreacted feed are subsequently fluids, lubricants and the like and which can be further distilled to remove monosilanes leaving behind a high- processed, for example, to form silicone elastomers, boiling component. resins, sealants and adhesives. [0010] The high-boiling component is a complex mix- [0003] Operation of the Direct Process results not only 30 ture that can include compounds containing SiSi, SiOSi, in the production of the desirable monosilanes, but also SiCSi, SiCCSi and SiCCCSi linkages alone or in combi- in a high boiling component typically considered to be nation in each molecule. The high-boiling component all materials with a boiling point higher than the particu- can include silicon containing solids and soluble and lar diorganodihalosilane produced in the process. The insoluble compounds of copper, aluminum and zinc. high-boiling component is a complex mixture that 35 The high-boiling component may contain, for example, includes compounds containing SiSi, SiOSi, SiCSi, organic substituted and non-organic substituted silanes, SiCCSi and SiCCCSi linkages in the molecules. Typical disilanes, trisilanes, disiloxanes, silane oligomers, compounds are described in US-A 2,598,435 and US-A siloxane oligomers, silalkylenes and silicon containing 2,681 ,355. The high-boiling component may also com- solids, all of which may be converted to monosilanes by prise silicon containing solids and soluble and insoluble 40 our process. compounds of copper, aluminum and zinc. [0011] The present process is especially useful for [0004] In current commercial operations for perform- converting polysilanes in the high-boiling component to ing the Direct Process, the high-boiling component can monosilanes, where the polysilanes are described by constitute as much as ten percent of the resultant prod- formula RaHbSinCI2n+2-a-b anc) where each R is a radi- uct. Therefore, it is desirable to convert the high-boiling 45 cal independently selected from alkyls comprising one component into more commercially desirable products to six carbon atoms, n = 2 to 20, a = 0 to 2n+2, b = 0 to to both reduce low-value by-products and to improve 2n+2 and a+b = 0 to 2n+2. raw material utilization. [001 2] The polysilanes useful in the present process [0005] The prior art for converting the high-boiling can consist of n number of silicon atoms where n is an component of the Direct Process into more usable mon- so integer from two to 20. Preferred is when n equals two. osilanes is represented by US-A 2,598,435; US-A The polysilanes can be substituted with a=0 to 2n+2 2,681,355; US-A 2,709,176 and US-A 2,842,580. number of R radicals, where each R is independently [0006] The aforementioned problems of the prior art selected from alkyls of one to six carbon atoms. The are solved by a catalyzed process for the high conver- radical R can be methyl, ethyl, propyl and t-butyl. Pre- sion of a high-boiling component produced by the Direct 55 ferred is when R is methyl. Process to monosilanes. Further, it is unexpected that [0013] The polysilanes in the high-boiling component such a catalyzed process could employ readily available can contain b number of hydrogen atoms substituted on and inexpensive catalysts which can be easily retained the silicon atoms, where b = 0 to 2n+2.

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[0014] The polysilanes in the high-boiling component [0022] In general, it is preferred that the activated car- can also contain from zero to 2n+2 chlorine atoms. bon have a diameter within a range of 0.001 mm to 20 [001 5] The high-boiling component can contain silalk- mm. More preferred is when the activated carbon has a ylenes, where each silalkylene can comprise one or diameter within a range of 0.01 mm to 5 mm and a sur- more silalkylene bonds described by formula Si(C)zSi 5 face area greater than 1000 m2/g. and z is an integer from one to six. Preferred is when z [0023] The weight of activated carbon in relation to the is an integer from one to three. The silalkylene mole- weight of high-boiling component and hydrogen chlo- cules can comprise SiSi bonds and SiOSi bonds as well ride added to the process will depend upon such factors as silalkylene bonds. The silicon atoms of the sila- as the type and size of the activated carbon, the chemi- lkylene molecules can be further substituted with the 10 cal composition of the high-boiling component, the proc- radical R, where R is as previously described, with chlo- ess temperature and the type of reactor employed. rine and with hydrogen. Preferred is when the silicon When the process is run as a batch or a semi-continu- atoms of the silalkylenes are substituted with methyl. ous process, a useful weight of activated carbon is con- [0016] The preferred high-boiling component is one sidered to be within a range of 0.1 to 30 weight percent resulting from the reaction of methyl chloride with sili- 15 of the combined weight of the high-boiling component con, the high-boiling component having a boiling point and the hydrogen chloride added to the process. greater than 70°C. This high-boiling component can [0024] The catalyst can be platinum supported on alu- contain Me2CISiSiMe2CI, Me2CISiSiMeCl2, mina. The amount of platinum can be from 0.1 to 10 MeCI2SiSiMeCl2, Me2CISiSi(Me)(CI)SiMeCI2, weight percent platinum. Preferred is when the amount Me2CISiCH2SiMe2CI, Me2CISiCH2SiMeCI2, 20 of platinum is within a range of 0.5 to 2.0 weight percent. MeCI2SiCH2SiMeCI2, Me2CISi(CH2)2SiMeCI2, The concentration of platinum retained on an alumina Me2CISi(CH2)3SiMeCI2, support used in the process will depend upon such fac- Me2CISiCH2Si(Me)(CI)SiMeCI2, tors as discussed for the use of activated carbon. In Me2CISiCH2Si(Me)(CI)CH2SiMeCI2 and general, when the process is run as a batch or semi- Me2CISiOSiMeCI2, where Me is methyl, all of which 25 continuous process a useful concentration of platinum may be converted to monosilanes by the present proc- on alumina support is considered to be that which pro- ess. vides a catalyst concentration within a range of 0.1 to 30 [0017] The high-boiling component is contacted with weight percent of the combined weight of the high-boil- hydrogen chloride, where the ratio of the weight of high- ing component and the halogen chloride added to the boiling component added to the reactor to the weight of 30 process. hydrogen chloride is within a range of 5:1 to 0.05:1. Pre- [0025] The catalyst can be a zeolite. The zeolite cata- ferred is where the ratio of the weight of high-boiling lyst can be of the natural occurring type, for example, component to the weight of hydrogen chloride is within chabazite, mordenite, erionite, faujasite and clinoptilo- a range of 3:1 to 1:1. lite. The zeolite catalyst can be a synthetic zeolite of the [0018] The process is conducted at a temperature 35 zeolite A, X, L or Y types or of the high silica synthetic within a range of 250°C. to 1000°C. A preferred temper- zeolite types such as ZSM-5 and ZSM-1 1 . Preferred is ature is within a range of 450°C. to 550°C. when the zeolite catalyst is selected from a group of [0019] While pressure is not critical to the present synthetic zeolite catalyst consisting of LZ-Y-64, LZ-Y-74 process, it is preferred that the process be run at a and LZ-M-8. gauge pressure not to exceed 6.9 MPa (1000 psi). More 40 [0026] The concentration of zeolite catalyst used in preferred is when the process is run at a pressure not the process will depend upon such factors as discussed exceeding 689.5 kPa (100 psi). for the use of activated carbon. In general, when the [0020] The process is conducted in the presence of a process is run as a batch or semi-continuous process, a catalyst selected from platinum supported on alumina, useful concentration of zeolite is considered to be within zeolite, AICI3 and AICI3 supported on a support selected 45 a range of 0.1 to 30 weight percent of the combined from carbon, alumina and silica. weight of the high-boiling component and the hydrogen [0021 ] Activated carbon catalyst is given as an exam- chloride added to the process. ple and is not within the scope of the present invention. [0027] The catalyst can be AICI3. The concentration of By "activated carbon", it is meant a microcrystalline, AICI3 catalyst used in the process will depend upon nongraphite form of carbon, having an internal porosity, 50 such factors as discussed for the use of activated car- the carbon having been activated by any standard proc- bon. In general, when the process is run as a batch or ess known in the art for producing activated carbon, for semi-continuous process, a useful concentration of example, chemical activation or gas activation as AICI3 catalyst is considered to be within a range of 0.1 described in Kirk-Othmer, Concise Encyclopedia of to 30 weight percent of the combined weight of the high- Chemical Technology, John Wiley & Sons publishers, 55 boiling components and the hydrogen chloride added to 1 985, p. 204 to 205. The activated carbon can be in the the process. form of, for example, flakes, chips, particles, powder or [0028] The catalyst can be AICI3 supported on a sup- pellets. port selected from carbon, alumina and silica. The

3 5 EP 0 635 510 B1 6 amount of AICI3 retained on the support is within a Example 2 (Not within the scope of the present inven- range of 0.1 to 30 weight percent. Preferred is when the tion). amount of AICI3 is within a range of 0.5 to 5.0 weight percent. The concentration of supported AICI3 will [0033] A high-boiling component resulting from the depend upon such factors as discussed above for the 5 reaction of methyl chloride with silicon was contacted use of activated carbon. In general, when the process is with hydrogen chloride in the presence of a packed bed run as a batch or a semi-continuous process, a useful of activated carbon catalyst. The process was con- concentration of is considered supported AICI3 catalyst ducted similar to that described in Example 1 , with the to be within a range of 0.1 to 30 weight percent of the high-boiling component composition, reactor design combined weight of the high-boiling component and the w and reaction temperature being the same. The reactor hydrogen chloride added to the process. was packed with 12 g of Calgon™ BPL 1 mm by 3.3 mm [0029] The optimum contact time for the high-boiling activated carbon pellets (Calgon, Pittsburgh, PA). The component and hydrogen chloride with the catalyst will high-boiling component was fed to the reactor at a rate depend on factors such as the type of catalyst, chemical of 92 g/h and hydrogen chloride was fed to the reactor composition of the high-boiling component and the is at a rate of 57 g/h. Gaseous product exiting the reactor degree of conversion and product selectivity desired. In was collected and analyzed as described in Example 1 . general, contact times within a range of one second to The collected product was found to comprise 93 weight five hours are useful. Longer contact times may be percent chlorosilane monomers and included those employed, but appear to offer no advantage and may chlorosilane monomers described for the product of result in excessive scission of silicon-carbon bonds and 20 Example 1 . silicon-hydrogen bonds present in the monosilanes. A preferred contact time in a continuous reactor system is Example 3 (Not within the scope of the present inven- within a range of one second to five minutes. tion). [0030] If desired, the monosilane containing product of the present process can be further separated by 25 [0034] A high-boiling component resulting from the standard means, for example, distillation to separate the reaction of methyl chloride with silicon was contacted monosilanes from a high-boiling component and the with hydrogen chloride in the presence of activated car- high-boiling component can then be recycled to the bon catalyst in a fluidized-bed reactor. The composition process. of the high-boiling component, reactor design and proc- [0031] The following examples are provided to facili- 30 ess temperature was similar to that described in Exam- tate understanding and to demonstrate the effective- ple 1 . The reactor was filled with 25 g of a 0.1 mm to 0.3 ness of the present invention. mm pulverized activated carbon (North American, Columbus, OH). The high-boiling component was fed to Example 1 (Not within the scope of the present inven- the reactor at a rate of 75 g/h and hydrogen chloride tion). 35 was fed to the reactor at a rate of 57 g/h. The process was conducted for 24 hours with gaseous product exit- [0032] A high-boiling component resulting from the ing the reactor being collected and analyzed as reaction of methyl chloride with silicon was contacted described in Example 1 . with hydrogen chloride in the absence of catalyst. The [0035] The collected product was determined to con- reactor consisted of a 2.5 cm diameter by 50 cm length 40 sist of similar species as identified in Example 1 . Of the quartz tube maintained at 500°C. The high-boiling com- product collected, 88 weight percent was chlorosilane ponent consisted of, by weight, 55% methylchlorodisi- monomers. lane, 5% disilmethylenes, 35% other polysilanes and silalkylenes and 5% silicon containing solids. The high- Example 4 boiling component was fed at a rate of 1 17 g/h to the 45 reactor and hydrogen chloride was fed to the reactor at [0036] A high-boiling component resulting from the 50 g/h. The process was conducted for one hour with reaction of methyl chloride with silicon was contacted gaseous product exiting the reactor being collected in a with hydrogen chloride in the presence of a zeolite cat- cold condenser. The condensed product was analyzed alyst. The process was conducted similar to that by gas chromatography using a thermal conductivity so described in Example 1, with the high-boiling compo- detector (GC-TC) and found to consist of 59 weight per- nent composition, reactor design and reaction tempera- cent chlorosilane monomers. Chlorosilane monomers ture being the same. The reactor was packed with 15 g detected included HSiCI3, SiCI4, MeHSiCI2, Me3SiCI, of zeolite LZ-Y-74 extruded 1.6 mm pellets (UOP Inc., MeSiCI3 and Me2SiCI2. Other species detected in the Tarrytown, NY). The high-boiling component was fed to condensed product included methylchlorodisilanes, dis- ss the reactor at a rate of 75 g/h and hydrogen chloride ilmethylenes, polysilanes and silalkylenes. was fed to the reactor at a rate of 57 g/h. The process was conducted for one hour with gaseous product exiting the reactor being collected and analyzed as

4 7 EP 0 635 510 B1 8 described in Example 1 . cal independently selected from alkyls comprising [0037] The collected product was determined to con- one to six carbon atoms, n = 2 to 20, a = 0 to 2n+2, sist of similar species as described in Example 1 . Of the b = 0 to 2n+2 and a+b = 0 to 2n+2. product collected, 81 weight percent was chlorosilane monomers. s 6. A process according to claim 4, where the high-boiling component comprises silalkylenes which con- Example 5 tain one or more silalkylene bonds and are described by formula Si(C)zSi and z = 1 , 2 or 3. [0038] A high-boiling component resulting from the reaction of methyl chloride with silicon was contacted to 7. A process according to claim 1 where the catalyst is with hydrogen chloride in the presence of a platinum on selected from zeolite LZ-Y-74 and platinum sup- alumina. The process was conducted similar to that ported on alumina. described in Example 1 , with the high-boiling component composition, reactor design and reaction tempera- Patentanspruche ture being the same. The reactor was packed with 1 6 g is of a one weight percent platinum on 1 .6 mm alumina 1. Verfahren zur Umwandlung einer hochsiedenden spheres (UOP Inc., Tarrytown, NY). The high-boiling Komponente, die aus der Reaktion eines Organo- component was fed to the reactor at a rate of 88 g/h and chlorids mit Silicium herruhrt, in Monosilane, wobei hydrogen chloride was fed to the reactor at a rate of 57 das Verfahren aus einem Inberiihrungbringen der g/h. The process was conducted for one hour with gas- 20 hochsiedenden Komponente mit Chlorwasserstoff eous product exiting the reactor collected and analyzed bei einer Temperatur im Bereich von 250- 1000°C as described in Example 1 . in Gegenwart eines Katalysators, der unter auf [0039] The collected product was determined to con- einem Aluminiumoxidtrager aufgetragenem Platin, sist of similar species as described in Example 1 . Of the Zeolith, AICI3 und auf einen Trager, der unter Koh- product collected, 82 weight percent was chlorosilane 25 lenstoff, Aluminiumoxid und Siliciumdioxid ausge- monomers. wahlt ist, aufgetragenem AICI3 ausgewahlt ist, besteht. Claims 2. Verfahren nach Anspruch 1 , wobei das Verfahren 1 . A process for converting a high-boiling component, 30 bei einem Manometerdruck durchgefiihrt wird, der resulting from the reaction of an organochloride 6,9 MPa (1000 psi) nicht ubersteigt. with silicon, to monosilanes, the process consisting of contacting the high-boiling component with 3. Verfahren nach Anspruch 1, wobei das Gew.-Ver- hydrogen chloride at a temperature within a range haltnis der hochsiedenden Komponente zu Chlor- of 250°C. to 1000°C. in the presence of a catalyst 35 wasserstoff, die dem Verfahren zugesetzt werden, selected from platinum supported on alumina, zeo- in einem Bereich von 5:1 bis 0,05:1 liegt. lite, AICI3 and AICI3 supported on a support selected from carbon, alumina and silica. 4. Verfahren nach Anspruch 1, wobei die hochsiedende Komponente aus der Reaktion von Methyl- 2. A process according to claim 1 where the process 40 chlorid mit Silicium herruhrt und die hochsiedende is conducted at a gauge pressure not to exceed 6.9 Komponente Polysilane, Silalkylene, siliciumhaltige MPa(1000 psi). Feststoff und losliche und unlosliche Verbindungen von Kupfer, Aluminium und Zink umfaBt. 3. A process according to claim 1 where the ratio of the weight of the high-boiling component to the 45 5. Verfahren nach Anspruch 1, wobei die hochsie- weight of the hydrogen chloride added to the proc- dende Komponente Polysilane der Formel ess is within a range of 5:1 to 0.05:1 . RaHbSinCl2n+2-a-b umfaBt, wobei ein jeder Rest R fur einen Rest steht, der unabhangig voneinander 4. A process according to claim 1 where the high-boil- aus Alkylresten mit 1 bis 6 Kohlenstoffatom(en) ing component results from the reaction of methyl so50 ausgewahlt ist, n 2 bis 20 bedeutet, a 0 bis 2n+2 chloride with silicon and the high-boiling compo- bedeutet, b 0 bis 2n+2 bedeutet und a+b 0 bis 2n+2 nent comprises polysilanes, silalkylenes, silicon bedeutet. containing solids and soluble and insoluble compounds of copper, aluminum and zinc. 6. Verfahren nach Anspruch 4, wobei die hochsie- 55 dende Komponente Silalkylene umfaBt, die eine 5. A process according to claim 1 where the high-boil- Oder mehrere Silalkylenbindungen enthalten und ing component comprises polysilanes described by der Formel Si(C)zSi mit z gleich 1 , 2 oder 3 entspre- formula RaHbSinCI2n+2-a-b. where each R is a radi- chen.

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7. Verfahren nach Anspruch 1 , wobei der Katalysator unter Zeolith LZ-Y-74 und auf Aluminiumoxidtrager aufgetragenem Platin ausgewahlt ist.

Revendications s

1 . Procede pour convertir un constituant a haut point d'ebullition, resultant de la reaction d'un chlorure organique avec du silicium, en monosilanes, le procede consistant a mettre le constituant a haut point 10 d'ebullition en contact avec du chlorure d'hydrogene a une temperature dans la gamme de 250 °C a 1000 °C en presence d'un catalyseur choisi parmi le platine supporte sur de I'alumine, une zeolite, AICI3 et AICI3 supporte sur un support choisi parmi 15 le carbone, I'alumine et la silice.

2. Procede selon la revendication 1 , le procede etant mis en oeuvre a une pression manometrique ne depassant pas 6,9 MPa (1000 psi). 20

3. Procede selon la revendication 1, dans lequel le rapport du poids du constituant a haut point d'ebullition au poids du chlorure d'hydrogene ajoute au procede est dans la gamme de 5:1 a 0,05:1. 25

4. Procede selon la revendication 1, dans lequel le constituant a haut point d'ebullition resulte de la reaction de chlorure de methyle avec du silicium, et le constituant a haut point d'ebullition comprend 30 des polysilanes, des silalkylenes, des matieres son- des contenant du silicium, et des composes solu- bles et insolubles de cuivre, d'aluminium et de zinc.

5. Procede selon la revendication 1, dans lequel le 35 constituant a haut point d'ebullition comprend des polysilanes represents par la formule RaHbSinCl2n+2-a-b. c)ans la°,uelle chaque R est un radical independamment choisi parmi les groupes alkyles comprenant un a six atomes de carbone, n 40 = 2 a 20, a = 0 a 2n+2, b = 0 a 2n+2 et a+b = 0 a 2n+2.

6. Procede selon la revendication 4, dans lequel le constituant a haut point d'ebullition comprend des 45 silalkylenes qui contiennent une ou plusieurs liaisons silalkylenes et sont represents par la formule Si(C)2Si ou z = 1 , 2 ou 3.

7. Procede selon la revendication 1, dans lequel le so catalyseur est choisi parmi la zeolite LZ-Y-74 et le platine supporte sur de I'alumine.