turopaiscnes patentamt European Patent Office © Publication number: 0 213 215 Office europeen des brevets A1 EUROPEAN PATENT APPLICATION Application number: 85110110.5 C01B © Int. CI.4: 33/107 , C01 B 33/04 , ~ B01J 31/02 © Date of filing: 12.0&85 © Date of publication of application: © Applicant: DENKI KAGAKU KOGYO KABUSHIKI 11.03.87 Bulletin 87/11 KAISHA 4-1, Yuraku-cho 1-chome © Designated Contracting States: Chiyoda-ku Tokyo(JP) BE CH GB IT LI NL © Inventor: Yamada, Mitsunori 55-1, Oaza-Suzawa Oml-machi Nishi-Kubiki-gun Niigata-ken(JP) Inventor: Ishii, Masaji 4- 33-4-302, Tsurumaki Setagaya-ku Tokyo(JP) inventor: Miyai, Akira 1964-5, Yamazaki-machi Mashida-shi Tokyo(JP) Inventor: Nakajima, Yukihlko 5- 33-18, Asahi-machl Atsugishi Kanagawa-ken(JP) Inventor: Sato, Shinsei 3-5-22, Mlnami-Rlnkan Yamato-shi Kanagawa-ken(JP) © Representative: Wgchtersh&user, GUnter, Dr. Tal29 D-8000 Munchen 2(DE) *) Chlorosilane disproportionation catalyst and method for producing a silane compound by means of the catalyst (57/ A chlorosilane disproportionation catalyst com- prising a tertiary amine of the formula: 5 R^ » N-R (A) R N £2 where each R represents an aliphatic hydrocarbon N group and the sum of carbon atoms in the three aliphatic hydrocarbon groups as R is 12 or more, and a tertiary amine hydrochloride of the formula: EL LU arox uopy centre 0 213 215 R\ + - N-RH CI (B) where R is as defined above. 2 U 213 215 2 CHLOROSILANE DISPROPORTIONATION CATALYST AND METHOD FOR PRODUCING A SILANE COM- POUND BY MEANS OF THE CATALYST as taught in U.S. Patent No. 2,732,282 has to be onv^iwanuuiNU ur I HE IINVCIN I IUIN conducted at a reaction temperature of 150°C and above; (ii) the method of using aliphatic FIELD OF THE INVENTION cyanamides as taught in U.S. Patent No. 2,732,280 5 requires the pretreatment with a Lewis acid; (iii) the The present invention relates to a chlorosilane method of using dimethylformamide or dimethyl- disproportionation catalyst and a method for pro- butylamide as taught in U.S. Patent No. 3,222,511 ducing a silane compound by means of the cata- is liable to deteriorate the catalyst used for the More lyst. particularly, the present invention relates reaction; and (iv) the method of using a tertiary to a chlorosilane disproportionation catalyst com- to amine containing a hydrocarbon composed of an prising a specific tertiary amine and a hydrochlo- alkyl group with 1 or 2 carbon atoms, as taught in ride thereof as the main components, and a meth- U.S. Patent No. 2,834,648 is required to be con- od for continuously producing a silane compound ducted at a temperature of 150 8 C and above, as is such as dichlorosilane, monochlorosilane or mon- the case with the catalyst of the above-mentioned Dsilane, by supplying a starting material 75 method (i), besides which a pressure resistant ves- chlorosilane and the catalyst into a reaction tower, sel has to be used, and, in spite of its equilibrated whereby the disproportionation reaction by means conversion ratio (calculated value) being 18% at 3f the specific catalyst and the separation by dis- the reaction temperature of 150" C, the actual con- tillation are conducted simultaneously. Further, the version ratio is as low as about 10%, hence a large Dresent invention relates to a process for producing 20 size apparatus is required to attain a desired quan- a silane compound efficiently by combining a pro- tity of production. :ess for synthesizing trichlorosilane from silicon of Further, U.S. Patent No. 4,113,845 discloses metallurgical grade or silicon tetrachloride, with the use of a fixed bed type reactor packed with an above method for producing a silane compound. anion exchange resin containing a tertiary amine as 25 the catalyst, wherein a starting material chlorosilane such as trichlorosilane or dichlorosilane is supplied DESCRIPTION OF THE PRIOR ART in a liquid state from one port of the reactor and reacted at a temperature of from 30 to 200 °C Demands for silane compounds such as dich- under a pressure of from 1 to 30 atm, whereby a orosilane (SiH,CI,), monochlorosilane (SiH,CI) and 30 reaction product comprising monosilane, monoch- nonosilane (SiH«) are expected to increase more lorosilane, dichlorosilane, trichlorosilane and silicon ind more as they are useful as the raw materials tetrachloride is obtainable from the other port of the or the high silicon purity to be used for elements reactor. However, since the above-mentioned equa- or semiconductors, solar cells, etc. In particular, it tions (1), (2) and (3) for the disproportionation reac- been las desired that dichlorosilane and mon- ts tion are equilibrium reactions, it is not possible to >silane be produced efficiently and in a large quan- complete the reaction of the starting material ity. chlorosilane 100%, even if the reaction is con- It is known to obtain a silane by the dispropor- ducted for an extended period of time. For exam- ionation reaction of SiHCI3 in the presence of a ple, the following Table indicates the equilibrated :atalyst, in accordance with the following equilib- to composition of monosilane, monochlorosilane, dich- ium reactions. lorosilane, trichlorosilane and silicon tetrachloride at (1) 2SiHCI3ssSiH,Cls + SiCI. a temperature of 80 °C when the disproportionation (2) 2SiH2CI,5* SiHCI, + SiH3CI reaction of trichlorosilane or dichlorosilane as the (3) 2SiH,CI s* SiH4 + SiH2CI, starting material has reached the state of equilib- (4) 4SiHCI3 » SiH, + 3SiCI, (as a whole) « rium. The disproportionation of chlorosilanes has »een studied since old, and various proposals have teen made. However, they still have disadvan- ages. For example, (i) the method of using nitrites 3 0 213 215 '4 (mol %) Starting Mono- Tri- Silicon material Mono- chloro- Dichloro- chloro- tetra- chloro- silane silane silane silane chloride silane Trichloro- 0.04 0.52 10.6 ' 77.1 11.8 silane Dichloro- 10.2 15.6 38.8 34.7 0.65 silane Further, even when the disproportionation reac- proportionation reaction. Thus, they are hardly ap- tion is brought to the equilibrated condition by 75 plicable to a practical operation on an industrial using trichlorosilane as the starting material, mon- scale. osilane and monochlorosilane contained in the re- action product are 0.04 mol % and 0.52 mol %, respectively, which figures indicate a very low re- SUMMARY OF THE INVENTION action rate for producing monosilane or monoch- 20 lorosilane in a single stage reaction. Therefore, It is an object of the present invention to pro- when, for example, monosilane is produced by vide a chlorosilane disproportionation catalyst using trichlorosilane as the starting material, the whereby a disproportionation reaction can be com- reaction product from the reaction vessel at the pleted in a short period of time at a low tempera- first stage is charged in a distilling device to sepa- 25 ture with a high conversion, by using a specific rate a mixture containing therein monosilane, mon- tertiary amine and a hydrochloride thereof as the ochlorosilane, and dichlorosilane, wherein dich- disproportionation catalyst. lorosilane is the principal component (composition A second object of the present invention is to A) and a mixture of trichlorosilane and silicon tetra- provide a method for continuously producing a chloride (composition B), and then the composition 30 silane compound such as monosilane, monoch- A is fed into the reaction vessel at the second lorosilane or dichlorosilane from a starting material stage, whereupon, since the equilibrated composi- chlorosilane such as trichlorosilane. tion from the disproportionation reaction contains A third object of the present invention is to 10.2 mol % of monosilane, as is apparent from the reuse silicon tetrachloride formed as a by-product table, monosilane can be separated and recovered 35 by the disproportionation reaction. As shown in the by feeding this reaction product into the distilling foregoing equation (4), when 1 mol of SiH« is apparatus. However, since the rate of reaction in produced by the disproportionation reaction, 3 mol the disproportionation reaction is low, the unreacted of SiCU is obtained as a by-product. In terms of substance should be circulated in a large quantity weight, 17 kg of SiCU is produced with respect to 1 for use, with the consequence that enormous 40 kg of SiH,. When SiH, is to be obtained in a large amount of energy was disadvantageous^ required quantity and at a low cost, this by-product SiCU is for the operations of the reaction vessel and the required to be re-used. distilling tower. Heretofore, in the method of using an ion- Furthermore, N-methyl-2-pyrrolidone, exchange resin, the by-product SiCU is introduced methylimidazole, tetramethylurea, tetramethyl- 45 into a reaction system consisting of silicon of met- guanidine, trimethylsilylimidazole, benzothiazole, allurgical grade, hydrogen, and hydrogen chloride, N,N-dimethylacetamide and the like, as disclosed then treated at a temperature of 600°C or so, and e.g. U.S. Patents No. 4,018,871 and 4,038,371 or re-converted to trichlorosilane (SiHCU). However, as Japanese Unexamined Patent Publication No. described in the foregoing, since the reaction rate 17918/1981, exhibit catalytic activities in the dis- 50 in the disproportionation reaction is low, a large proportionation reaction of silane compounds. How- amount of unreacted substance needs to be used ever, they are per se solid, or become powdery by recycling, on account of which the reaction solid when brought in contact with a silane com- vessel and the distilling apparatus should be made pound such as trichlorosilane or dichlorosilane. large in scale. Thus, an enormous amount of en- Consequently, it becomes difficult to separate them 55 ergy is disadvantageously required.