JP2014234335A - Silane compound production apparatus and production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silane compound production apparatus and production method that does not require a large scale distillation column (rectification column), has high energy efficiency, uses a small amount of cryogenic coolant, and that is capable of continuous stable separation and purification of multiple silane compounds.SOLUTION: The silane compound production apparatus comprises: a first rectification column 1 into which a fed material containing a plurality of silane compounds is introduced; a first cold trap 2 into which a first gas phase component containing a lower order silane derived from the column top 1a of the first rectification column 1 is introduced and cooled to be subjected to gas liquid separation; a second rectification column 3 into which a first liquid phase component containing as main constituent a higher order silane derived from the column bottom 1b of the first rectification column 1; and a second cold trap 4 into which a second gas phase component derived from the column top 3a of the second rectification column 3 is introduced and cooled to be subjected to gas liquid separation. The first cold trap 2 consists of a first separation tank 2a and a second separation tank 2b whose preset temperatures are sequentially lowered.

Description

  The present invention relates to a production apparatus and a production method for a silane compound, and specifically relates to a production apparatus and a production method suitable for producing, for example, a silane compound useful as an industrial silicon material, in particular, high-purity disilane. .

  Silane compounds, especially monosilane and disilane, are used as raw materials for silicon wafers, and there is a great demand especially in various processes including manufacturing processes for semiconductors and solar cells, and they are produced and supplied in large quantities as liquefied gas. . Higher order silanes such as disilane are produced using a lower order silane such as monosilane as a raw material using a high pressure / high temperature reactor, and several production techniques have been proposed and put into practical use.

  For example, a system for producing a higher order silane as shown in FIG. 4 can be cited (see, for example, Patent Document 1). Specifically, in the system for producing the higher order silane, for example, higher order silane is produced from lower order silane such as monosilane to disilane, disilane to trisilane, and trisilane to tetrasilane. A first lower silane-containing fluid 120 is introduced into the preheater 100. The preheater 100 heats the low-order silane-containing fluid 120 to a temperature within the first reaction temperature range. The preheater 100 heats the first lower silane containing fluid 120 to produce a heated lower silane containing fluid 122 that is introduced into the first reaction vessel or first reaction zone 102. The first gas mixture 124 exits the first reaction zone 102. The gas mixture 124 contains a major component low order silane, a small amount of higher order silane, and a smaller amount of higher order higher order silane. The gas mixture 124 also contains hydrogen and lower order lower silanes. The gas mixture 124 is introduced into the distillation column 104. The liquid mixture is used to concentrate the gas mixture 124 and include a top fluid 130 containing a relatively high concentration of hydrogen and / or lower order lower silane, a higher order containing a higher concentration of higher order silane. The distillation column 104 has a concentrator 112 that separates into a silane containing fluid 132 and a second lower silane containing fluid 126 that is recycled to the preheater 100. The overhead fluid 130 exits the system. The higher order silane-containing fluid 132 can be collected in the pot 108 of the distillation column 104 and further purified by distillation after the reaction process is stopped to remove unwanted higher order higher order silanes (paragraph 0013). ~ 0019).

JP 2008-536784 A

However, in the production system and production method of higher silane as described above, the following various problems may occur.
(I) After the preparation reaction of the silane compound under high temperature conditions in the reactor (first reaction zone 102 according to the above production system), the reaction product is cooled to a predetermined temperature, and a part of the reaction product is refluxed The reaction components are re-reacted to ensure high reaction efficiency and reaction product stability. The first gas mixture 124 delivered from the first reaction zone 102 has a high temperature of 330 to 350 ° C., and several stages of cooling treatment are required to separate and remove each silane compound from the high temperature reaction product. In addition, a distillation column (rectification column) is indispensable in order to obtain high separation efficiency. However, in the above configuration example, when introduced into the distillation column 104, a very large heat exchange area, that is, a column height, is required to cool the column top to a low temperature at which higher order silane can be liquefied. There was a problem that was necessary. Specific amounts will be described later.
(Ii) Further, the cooling treatment has a problem that it is necessary to use a very large amount of liquid nitrogen for the refrigerant used in the concentrator 112 to liquefy the low-order silane at the top of the tower. In particular, since the partial pressure of disilane and trisilane is very low, it does not function with a refrigerant of about −30 ° C. such as normally used brine, and a cryogenic refrigerant such as liquid nitrogen is used for a large amount of cold traps. There was a problem that was necessary. Specific amounts will be described later.
(Iii) Especially in actual use sites, the demand for downsizing and reduction of cryogenic refrigerants for such production systems is very strong due to the limitations of installation locations and incidental facilities, and there is a great demand for versatility such as maintenance. It was an issue.

  The object of the present invention is that a large-scale distillation tower (rectification tower) is not required in the production process of the silane compound, the energy efficiency is high, the amount of the cryogenic refrigerant used is small, and a plurality of silane compounds are continuously used. An object of the present invention is to provide an apparatus and a method for producing a silane compound that can be separated and purified with high stability.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by the following silane compound production apparatus and production method, and have completed the present invention.

  The apparatus for producing a silane compound according to the present invention includes at least a first rectifying column into which a raw material containing a plurality of fed silane compounds is introduced, and a lower order derived from the top of the first rectifying column. A first liquid mainly composed of a first cold trap into which a first gas phase component containing silane is introduced, cooled and gas-liquid separated, and a high-order silane derived from the bottom of the first rectifying column. A second rectifying column into which a phase component is introduced, and a second cold trap into which a second gas phase component derived from the top of the second rectifying column is introduced, cooled and gas-liquid separated. The first cold trap has at least a first separation tank and a second separation tank, and is composed of a plurality of stages of separation tanks whose set temperatures are successively reduced, and the first separation tank and the second separation tank The first condensate and the second condensate derived from the upper stage of the first fractionator And introducing monosilane contained in the third gas phase component derived from the first cold trap, taking out disilane contained in the fourth gas phase component derived from the second cold trap, and Trisilane contained in the second liquid phase component derived from the bottom of the rectification column is taken out.

In the silane compound production system, the obtained reaction product (raw material in the present invention) has a tower height necessary for a predetermined cooling treatment in order to ensure an effective treatment in the distillation tower as described above. And an appropriate refrigerant is required. On the other hand, although the temperature gradient from the bottom of the rectifying tower heated by the reboiler and the top of the rectifying tower where the higher silane is cooled and liquefied varies depending on the tower diameter of the rectifying tower, the rectifying tower is expanded by increasing the tower diameter. It is difficult to downsize. In addition, it is difficult to reduce the size of the rectification column with different temperature gradients, and there is a limit to the improvement of the rectification column structure itself. In the process of verifying the production process of the silane compound, the present inventor does not need a large distillation column (rectification column) with such a configuration from the following knowledge, and has high energy efficiency. It has become possible to provide an apparatus for producing a silane compound in which the amount of low-temperature refrigerant used is small and a plurality of silane compounds can be continuously and stably separated and purified.
(I) For example, in a rectification tower having a tower bottom of about 0 ° C. and a tower top of about −120 ° C. as exemplified in FIG. 4, monosilane (bp about −112 ° C.) and disilane (bp about −14 ° C.) are Due to the large difference in boiling points, the separation of disilane and monosilane is almost complete at about −30 ° C. For this reason, the range from about −30 ° C. to the top of the column in the rectification column to 120 ° C. is gas-liquid heat exchange, but the heat transfer rate between the two is very small, so sufficient heat exchange is possible. This requires a large contact area, and as a result, the rectification column tends to be high. That is, the function as an efficient rectification column is about −30 ° C., and the separation treatment at a temperature lower than that can be performed by using a separate means such as forced cooling from the outside. The knowledge that it is efficient was obtained.
(Ii) The composition of the products taken out from the rectification towers of various heights and this were further subjected to cooling treatment (cold trap), and their technical effects were confirmed. In the example of (i), disilane was mainly used. A rectification column having a small column height by using a cold trap comprising a plurality of separation tanks whose set temperatures are successively reduced, including a condenser of about -30 ° C. capable of obtaining a reflux liquid as a component. In the present invention, it was found that high separation efficiency for each silane compound can be obtained without impairing the rectifying function.
(Iii) At this time, it was not necessary to use a cryogenic refrigerant in the upstream stage of the plurality of separation tanks, and it was found that the normally used brine is sufficient.
(Iv) From the above, the multistage separation tank in which the product from the rectification tower having a height that is a fraction of the height of the conventional tower includes at least two separation tanks, and the set temperatures are sequentially reduced. Introduced into a cold trap composed of the above, the higher silane and lower silane are cooled and gas-liquid separated in stages, and the condensate from each separation tank is returned to the rectification column as the source stream. As a result, it was found that the rectification tower can be miniaturized. In addition, the upstream stage cooling can use brine which is usually used in the field, so that the amount of the cryogenic refrigerant used can be greatly reduced.
The “low-order silane”, “high-order silane” and “silane compound” mentioned here will be described later.

The present invention is the above-described apparatus for producing a silane compound, wherein an introduction portion of the second condensate derived from the second separation tank into the first rectification column is derived from the first separation tank. It arrange | positions in the upper stage rather than the introduction part to the said 1st rectification tower of 1 condensate, It is characterized by the above-mentioned.
In the first cold trap of the apparatus for producing a silane compound, in the first separation tank, a mixture of low-order silane and high-order silane concentrated as a gas phase is led out and high-order silane partially containing low-order silane A first condensate containing as a main component is derived. On the other hand, in the second separation tank, a third gas phase component mainly composed of low-order silane is derived, and high-order silane partially containing low-order silane (higher concentration than the first condensate) is mainly used. The second condensate is derived. At this time, it is preferable to arrange | position the introduction part to the 1st rectification column of a 2nd condensate in the upper stage rather than the introduction part to the said 1st rectification column of a 1st condensate. That is, when the condensate is refluxed in the rectification column, in order to utilize the rectification function of the rectification column, it is preferable to introduce the condensate at a position corresponding to the temperature gradient in the column. Has a lower boiling point than the first condensate, and by performing refluxing that matches the characteristics of the condensate, it is more energy efficient and enables continuous and stable separation and purification of multiple silane compounds. It became possible to do.

The present invention provides an apparatus for producing the above silane compound, wherein a pre-cold trap is provided in a flow path through which a raw material is introduced into the first rectification column, and the pre-cold trap, the first separation tank, and the first Brine is used as the refrigerant supplied to the two cold trap, and cryogenic refrigerant such as liquid nitrogen or methanol / dry ice is used as the refrigerant supplied to the second separation tank.
As described above, in the apparatus for producing a silane compound according to the present invention, a multi-stage cooling process is performed in order to separate and purify a silane compound such as monosilane, and an appropriate temperature setting is performed in various places. For example, the temperature of the raw material introduced into the rectifying column is preferably low, but when it is introduced into the middle of the rectifying column, it is equal to or slightly lower than the temperature corresponding to the temperature gradient in the rectifying column. The set temperature of the first separation tank is preferably equal to or lower than the temperature at which the first condensate containing high-order silane as a main component is generated. On the other hand, the set temperature of the second separation tank is preferably equal to or lower than the temperature at which the third gas phase component in which high-order silane is hardly mixed is generated. At this time, for the former, it is possible to use a brine that is usually used in the field, and to use a cryogenic refrigerant only for the latter, so it is possible to greatly reduce the amount of cryogenic refrigerant used in the entire apparatus. It became.

The present invention is an apparatus for producing the silane compound, comprising a return flow path connecting a tank bottom of the second separation tank and a tank top of the first separation tank, a feed pump and a regulating valve in the return flow path Is provided.
As described above, in the second separation tank, the second condensate containing mainly the higher order silane containing a part of the lower order silane is derived. At this time, by refluxing the second condensate to the first rectifying column, the yield of, for example, disilane out of the low-order silane or the high-order silane can be increased, while in the first rectifying column, That load will increase. Moreover, since the 2nd condensate is cooled and produced | generated by a cryogenic refrigerant | coolant, it has big cold heat. According to the present invention, by refluxing the second condensate to the first separation tank, the cold energy can be utilized, the energy efficiency is higher, a plurality of silane compounds can be separated and purified, and the first separation tank By performing the separation treatment again in, the yield of the low-order silane and the high-order silane can be increased while reducing the load on the first rectification column.

In addition, the present invention is a method for producing a silane compound using any one of the above-described apparatus for producing a silane compound, and includes at least the following steps.
(1) The fed raw material containing a plurality of silane compounds is introduced into the first fractionator,
(2) First rectification is carried out in the first rectification column, a first gas phase component containing low-order silane is led out from the top of the first rectification column, and the first main component containing high-order silane from the bottom of the column. The liquid phase component is derived,
(3) The first gas phase component is introduced into a first cold trap that includes at least a first separation tank and a second separation tank, and is composed of a plurality of stages of separation tanks whose set temperatures are successively reduced,
(3-1) Cooled and gas-liquid separated in the first cold trap, the third gas phase component is derived,
(3-2) The first condensate and the second condensate derived from the first separation tank and the second separation tank are derived,
(3-3) The first condensate and the second condensate are introduced into the upper stage of the first rectifying column,
(4) The first liquid phase component is introduced into the second rectification column,
(5) rectification is performed in the second rectification column, the second gas phase component is derived from the top of the second rectification column, and the second liquid phase component is derived from the bottom of the column,
(6) The second gas phase component is introduced into the second cold trap,
(7) Cooled and gas-liquid separated in the second cold trap, the fourth gas phase component is derived,
(8) Monosilane contained in the third gas phase component is taken out, disilane contained in the fourth gas phase component is taken out, and trisilane contained in the second liquid phase component is taken out.
Such a configuration does not require a large-scale distillation column (rectification column), has high energy efficiency, uses a very low temperature refrigerant, and enables continuous and stable separation and purification of multiple silane compounds. It has become possible to form a method for producing a silane compound.

The present invention is a method for producing the above silane compound, wherein a part or all of the second condensate is returned and introduced into the first separation tank, and the return flow rate is any of the monosilane, disilane, and trisilane. Alternatively, flow rate control is performed using some of the extracted amounts as an index.
With such a configuration, it is possible to separate and purify a plurality of silane compounds by making use of the cold heat of the second condensate, and to separate and purify a plurality of silane compounds. It was possible to increase the yield of low-order silane and high-order silane while reducing the load on the distillation column.

Schematic which shows the 1st structural example of the manufacturing apparatus of the silane compound which concerns on this invention. Schematic which shows the 2nd structural example of the manufacturing apparatus of the silane compound which concerns on this invention. Schematic which shows the 3rd structural example of the manufacturing apparatus of the silane compound which concerns on this invention. Schematic showing a configuration example of a high-order silane production system according to the prior art

  An apparatus for producing a silane compound according to the present invention (hereinafter referred to as “this apparatus”) includes at least a first rectifying column into which a raw material containing a plurality of fed silane compounds is introduced, and a tower of the first rectifying column A first cold trap introduced with a first gas phase component containing a low-order silane derived from the top, cooled and gas-liquid separated, and a high-order silane derived from the bottom of the first fractionator A second rectifying column into which the first liquid phase component as a main component is introduced, and a second gas phase component derived from the top of the second rectifying column are introduced, cooled, and gas-liquid separated. A second cold trap, and the first cold trap includes at least a first separation tank and a second separation tank, and includes a plurality of stages of separation tanks whose set temperatures are sequentially reduced, and the first separation tank And the first condensate and the second condensate derived from the second separation tank While being introduced into the upper stage of the tower, monosilane contained in the third gas phase component derived from the first cold trap is taken out, and disilane contained in the fourth gas phase component derived from the second cold trap is taken out. The trisilane contained in the second liquid phase component derived from the bottom of the second rectification column is taken out. Manufacture of silane compounds that do not require a large distillation column (rectification column), have high energy efficiency, use a very low temperature refrigerant, and can continuously separate and purify multiple silane compounds. apparatus. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  Here, “low-order silane” refers to monosilane or a silane compound containing monosilane as a main component (for example, a mixture of monosilane and disilane). Contains a substance close to monosilane (for example, within ± 20%). “Higher order silane” means polysilane such as disilane or trisilane or a silane compound containing polysilane as a main component. However, not only the polysilane in the mixture is 50% or more but also a substance having a boiling point exceeding disilane. Including. Furthermore, in addition to these, “silane compound” is a generic term for compounds containing higher order silanes. In the following, the raw materials are specified, and as in the verification target described later, a monosilane that is a low-order silane as a main component, a disilane that is a high-order silane, a silane compound containing a small amount of trisilane, and a small amount of hydrogen are examples May be described as follows. Of course, the present invention is not limited to this, and the present invention can also be applied to the case where a compound having a similar boiling point is included, or when tetrasilane (bp about 107 ° C.) having a higher boiling point than trisilane and other compounds are included. Needless to say.

<Basic configuration example of this device>
An outline of a basic configuration example of the present apparatus is shown in FIG. 1 (first configuration example). The apparatus includes a first rectifying column 1 into which a feed material containing a plurality of silane compounds fed is introduced, and a first gas phase containing a low-order silane derived from the top 1a of the first rectifying column 1. The first cold trap 2 into which the components are introduced, cooled and gas-liquid separated, and the first liquid phase component mainly composed of higher silane derived from the column bottom 1b of the first rectifying column 1 are introduced. The second rectifying column 3 and the second cold trap 4 into which the second gas phase component derived from the top 3a of the second rectifying column 3 is introduced, cooled and gas-liquid separated are provided. The first cold trap 2 is composed of a first separation tank 2a and a second separation tank 2b whose set temperatures are successively reduced, and a first condensate liquid derived from the first separation tank 2a and the second separation tank 2b and The second condensate is introduced into the upper introduction sections 1c and 1d of the first rectifying column 1. The raw material is introduced into the first rectifying column 1, monosilane contained in the third gas phase component derived from the first cold trap 2 is taken out, and contained in the fourth gas phase component derived from the second cold trap 4. Disilane is taken out, and trisilane contained in the second liquid phase component derived from the bottom 3b of the second rectifying column 3 is taken out.

  Into the first rectifying column 1, a raw material containing monosilane as a main component and containing disilane, a small amount of trisilane, and a small amount of hydrogen is introduced. At this time, a cooler 5 is provided in the raw material introduction flow path L1, the raw material is cooled to about 0 to 10 ° C. in advance, and is introduced into the middle stage (middle 1e) of the first fractionator 1 in a liquefied state. It is preferable. By cooling the raw material fed from a reactor (not shown) or the like (in the case of a reaction product, about 200 to 300 ° C.) to the optimum operating conditions of the first fractionator 1 in advance. The load on the first rectifying column 1 can be reduced, and a high-purity silane compound can be efficiently extracted. The warm heat recovered by the coolant such as cooling water supplied to the cooler 5 is used as a heat source for the present device or an auxiliary device.

  Among the raw materials introduced into the first rectifying column 1, there are monosilane which is a low-boiling low-order silane and silanes such as high-boiling disilane and trisilane (bp about 53 ° C.) which are higher-order silanes. Compound is mixed. Depending on the process by which the raw material is manufactured, a small amount of hydrogen having a lower boiling point (bp about −253 ° C.), a high boiling point tetrasilane (bp about 107 ° C.), and the like may be present. Since the difference between the boiling points of the low-order silane and the high-order silane to be separated is large, for example, when taking out a desired disilane, the raw material is introduced into the middle 1e of the first rectification column 1 to The temperature gradient in one rectification column 1 can be effectively used to perform rectification efficiently. Further, in the first rectifying column 1 of the present apparatus, a predetermined length (for example, about 3 m) is formed in a vertical direction without using a perforated plate or a tray by combining with the first cold trap 2 described later. In addition to obtaining knowledge that a sufficient separation function can be ensured by the structure in which the temperature difference between the upper and lower portions of the hollow body is large, it was possible to demonstrate as described later. Specifically, as described above, for example, monosilane separation from disilane is almost completed at about −30 ° C., and therefore, by using a reboiler 1r at about 0 ° C., the inner diameter is about 100 mm to several hundreds mm, By having about 2 m to several m, the first rectifying column 1 having a column top temperature of about −30 ° C. can be constituted. At this time, the first gas phase component containing monosilane (low-order silane) having a temperature of about −50 to −20 ° C. is derived from the top 1 a of the first rectifying column 1 under a low pressure condition of about 1 to 2 bar (A). Then, a first liquid phase component mainly composed of disilane (higher order silane) having a temperature of about −10 to 10 ° C. is derived from the tower bottom 1b.

  The first gas phase component containing low-order silane derived from the tower top 1a of the first rectifying tower 1 is introduced into the first cold trap 2 via the flow path L3. The 1st cold trap 2 is comprised from the 1st separation tank 2a and the 2nd separation tank 2b in which preset temperature was made low sequentially. The set temperature of the first separation tank 2a is preferably equal to or lower than the temperature at which the first condensate containing high-order silane as a main component is generated, and low-pressure conditions are preferable. For example, the temperature is set to about −30 to −20 ° C., and the pressure is set to about 1 to 2 bar (A). The introduced first gas phase component is cooled and condensed, gas-liquid separated, and a concentrated mixture of low-order silane and high-order silane is led out in the gas phase, and a high-order containing a part of the low-order silane. A first condensate containing silane as a main component is derived. The set temperature of the second separation tank 2b is preferably equal to or lower than the temperature at which a gas phase component in which high-order silane is hardly mixed is generated, and low-pressure conditions are preferable. For example, the temperature is set to about −125 to −115 ° C., and the pressure is set to about 1 to 2 bar (A). The gas phase mixture is introduced through the flow path L4, and after cooling and condensation, gas-liquid separation is performed, and a third gas phase component mainly composed of low-order silane is derived and concentrated low A first condensate containing a high-order silane containing a part of secondary silane as a main component is derived. The cooling of the second separation tank 2b, in the case of a raw material mainly composed of disilane, has a melting point of disilane of about −130 ° C., so that the temperature is higher and the monosilane bp is about −112 ° C. or less. It is preferable to use a cryogenic refrigerant. Examples of the cryogenic refrigerant include liquid nitrogen and methanol / dry ice. On the other hand, the cooling of the first separation tank 2a can ensure its function by using brine that is normally used in the field, so that the amount of cryogenic refrigerant used can be greatly reduced. . The first condensate is introduced into the upper stage introduction portion 1c of the first rectification tower 1 via the flow path L5, and the second condensate is introduced into the upper stage of the first rectification tower 1 via the flow path L7. Part 1d is introduced. At this time, by setting the flow rate of the first condensate >> the flow rate of the second condensate, the amount of the cryogenic refrigerant used can be reduced and the temperature gradient in the first rectifying column 1 can be reduced by the stabilization. The stabilization function can be stabilized.

  Here, the introduction part 1d of the second condensate derived from the second separation tank 2b to the first rectification tower 1 is used as the first rectification tower 1 of the first condensate derived from the first separation tank 2a. It is preferable to arrange in the upper stage than the introduction part 1c. Since the second condensate has a lower boiling point than the first condensate, the condensate is utilized at a position corresponding to the temperature gradient in the first rectifying column 1 by taking advantage of the difference in characteristics between the two condensates. By refluxing, rectification with higher energy efficiency becomes possible, and a plurality of silane compounds can be continuously and stably separated and purified.

  Further, in the first cold trap 2 composed of the first separation tank 2a and the second separation tank 2b whose set temperatures are successively lowered, the first function shortened by utilizing the unique function of each separation tank. A rectifying function higher than before can be achieved at the height of one rectifying column 1. That is, the first separation tank 2a has a function as a condenser of the first rectifying column 1 and increases the first condensate derived therefrom and refluxed to the first rectifying column 1, thereby It is possible to have a function of reducing the height of one rectifying column 1. Specifically, the first condensate can be increased by adjusting the flow rate and lowering the set temperature (selecting the refrigerant and increasing the flow rate). In particular, the lower the tower height, the higher the vapor pressure at the top of the tower, and the amount of the first gas phase component introduced and the first condensate can be increased, so that the function of the first separation tank 2a can be further utilized. . Further, by setting a large amount of the first condensate (lowering the set temperature), it is possible to reduce the load on the second separation tank 2b in the subsequent stage and reduce the amount of the cryogenic refrigerant used. In particular, when there is a large amount of higher-order silane contained in the first gas phase component, the amount of the cryogenic refrigerant used can be further reduced by increasing the condensation / separation in the first separation tank 2b.

  On the other hand, as long as the second separation tank 2b is equal to or lower than the cooling temperature at which higher order silane can be condensed and separated, there is almost no restriction on the cooling temperature (the supply amount of the cryogenic refrigerant). Therefore, the function of the second separation tank 2b can be ensured by ensuring the minimum supply amount of the cryogenic refrigerant. Further, by adjusting the cooling temperature below that, the vapor pressure of the low-order silane can be controlled, and the amount of extraction can be adjusted. At this time, for example, when the content of monosilane in the raw material is large and the amount of higher order silane, particularly disilane, is large, the amount of monosilane introduced from the first separation tank 2b to the second separation tank 2b is increased. However, the evaporation heat of monosilane is about 2.63 kcal / mol (−111 ° C.), while the evaporation heat of disilane is about 5.11 kcal / mol (−14.3 ° C.). The increase in cold heat required for liquefaction accompanying the increase in monosilane is small. That is, the second separation tank 2b has a function suitable for separating monosilane having a small evaporation heat.

  The first liquid phase component mainly composed of higher order silane derived from the tower bottom 1b of the first rectifying column 1 is introduced into the second rectifying column 3 through the flow path L2. The first liquid phase component introduced into the second rectifying column 3 contains a silane compound such as disilane or trisilane, which is a higher order silane, and forms a bp of about 0 ° C. Using the difference in boiling point between disilane (bp about −14 ° C.) and trisilane (bp about 53 ° C.) or tetrasilane (bp about 107 ° C.), it is introduced into the middle stage (middle 3e) of the second rectification column 3. Thus, the temperature gradient in the second rectifying column 3 can be effectively used to perform rectification efficiently. Specifically, disilane or trisilane is vaporized by heating to about 60 to 80 ° C. with a reboiler 3r provided at the tower bottom 3b, for example. Separation of disilane from trisilane is almost completed at about -5 ° C. Therefore, by setting the set temperature at the top 3a of the column to about -10 to 0 ° C, condensation and separation of trisilane and disilane in the gas phase state are reduced. It can be done reliably. Under a low pressure condition of about 1 to 2 bar (A), a fourth gas phase component mainly composed of disilane having a temperature of about −10 to 0 ° C. is derived from the top 3 a of the second rectifying column 3, and from the bottom 3 b. A second liquid phase component mainly composed of trisilane having a temperature of about 60 to 80 ° C. is derived. At this time, the separation of disilane from trisilane is such that the difference in boiling point is small compared to the difference in boiling point between disilane and monosilane. Will not be big. Therefore, this device does not require a large-scale distillation column (rectification column), has high energy efficiency, uses a very low temperature refrigerant, and continuously and stably separates and purifies a plurality of silane compounds. It can be carried out.

  The fourth gas phase component derived from the tower top 3a of the second rectification tower 3 is introduced into the second cold trap 4 via the flow path L9. The set temperature of the second cold trap 4 is preferably equal to or lower than the temperature at which the third condensate containing trisilane is generated, and is preferably under low pressure. For example, the temperature is set to about −10 to 0 ° C. and the pressure is set to about 1 to 2 bar (A). The cooling of the second cold trap 4 can ensure its function by using brine as a refrigerant. The introduced fourth gas phase component is gas-liquid separated after cooling / condensation, high purity disilane is led out in the gas phase via the flow path L10, and high-order silane partially containing trisilane is the main component. The third condensate is derived. The third condensate is introduced into the upper introduction part 3c of the second rectification tower 3 via the flow path L11.

  As described above, in this apparatus, from the first cold trap 2 to the monosilane (some low-boiling substances such as hydrogen may be included), from the second cold trap 4 to the high-purity disilane, the second fractionator 3 Trisilane (some of which may contain high boiling point substances such as tetrasilane) can be taken out from the tower bottom 3b.

[Method for producing silane compound using this apparatus]
By using the above apparatus and operating the following procedure, the energy efficiency is high, the amount of the cryogenic refrigerant used is small, and a plurality of silane compounds can be separated and purified continuously and stably. Can be formed (hereinafter referred to as “the present method”).
(1) The fed raw material containing a plurality of silane compounds is introduced into the first rectifying column 1,
(2) The rectification is performed in the first rectification column 1, the low order silane is derived from the top 1a of the first rectification column 1, and the high order silane is derived from the bottom 1b.
(3) A multi-stage separation in which the low-order silane derived from the top 1a of the first rectifying column 1 has at least a first separation tank 2a and a second separation tank 2b, and the set temperatures are successively reduced. Introduced into the first cold trap 2 composed of a tank,
(3-1) Cooled in the first cold trap 2 and separated into gas and liquid, and the gas phase component is derived,
(3-2) The first condensate and the second condensate derived from the first separation tank 2a and the second separation tank 2b are derived,
(3-3) The first condensate and the second condensate are introduced into the upper stages 1c and 1d of the first rectifying column 1,
(4) Higher order silane derived from the bottom 1b of the first rectifying column 1 is introduced into the second rectifying column 3,
(5) The rectification is performed in the second rectification column 3, the gas phase component is derived from the tower top 3a of the second rectification column 3, and the liquid phase component is derived from the tower bottom 3b.
(6) The gas phase component derived from the top 3a of the second rectification column 3 is introduced into the second cold trap 4,
(7) Cooled and gas-liquid separated in the second cold trap 4 to derive a gas phase component;
(8) The monosilane contained in the gas phase component derived from the first cold trap 2 is taken out, the disilane contained in the gas phase component derived from the second cold trap 4 is taken out, and the bottom of the second rectifying column 3 Trisilane contained in the liquid phase component derived from 3b is taken out.

  Further, in this method, a part or all of the second condensate is returned to and introduced into the first separation tank 1, and the return flow rate is an index of any one of monosilane, disilane, trisilane or some of the extracted amounts. As described above, it is preferable to perform flow rate control. Utilizing the cold of the second condensate, it is more energy efficient, can separate and purify a plurality of silane compounds, and is separated again in the first separation tank, so that the load on the first rectification column The yield of low-order silanes and high-order silanes can be increased while reducing.

<Other configuration examples of the apparatus>
As another configuration example of the present apparatus, an outline of an apparatus in which the second cold trap 4 includes a plurality of separation tanks is shown in FIG. 2 (second configuration example). In the first configuration example, the second cold trap 4 includes the third separation tank 4a and the fourth separation tank 4b whose set temperatures are successively lowered, and is derived from the third separation tank 4a and the fourth separation tank 4b. The third condensate and the fourth condensate are introduced into the upper introduction portions 3 c and 3 d of the second rectifying column 3. In the third separation tank 4a and the fourth separation tank 4b, brine can be used as the refrigerant. By introducing the higher order silane derived from the tower top 3a of the second rectifying column 3 into the third separation tank 4a and the fourth separation tank 4b, the disilane component in the higher order silane remains in a small amount. And higher order polysilanes. Also, the second cold trap 4 at the top of the second rectifying column 3 is formed in the same configuration as the first cold trap 2 provided at the top of the first rectifying column 1 in the first configuration example. Thus, the energy efficiency can be further improved and the height of the second rectifying column 3 can be shortened.

  Specifically, for example, from the tower top 3a of the second rectifying tower 3 heated to about 60 to 80 ° C. at the tower bottom 3b, the high boiling point component mainly composed of disilane having a temperature of about 20 to 40 ° C. is enriched. The second gas phase component was derived, introduced into the third separation tank 4a set to about 0 to 10 ° C. via the flow path L9, and further set to about −10 to 0 ° C. via the flow path L10. It is introduced into the fourth separation tank 4b and further separated. The separated gaseous disilane (fourth gas phase component) is taken out from the upper part of the fourth separation tank 4b through the flow path 12. The third condensate derived from the third separation tank 4a is introduced into the upper introduction part 3c of the second rectification tower 3 via the flow path L11, and the fourth condensate derived from the fourth separation tank 4b. The condensate is introduced into the upper introduction part 3d of the second rectification tower 3 via the flow path L13. The raw material is introduced into the first rectifying column 1, monosilane contained in the third gas phase component derived from the first cold trap 2 is taken out, and contained in the fourth gas phase component derived from the second cold trap 4. The trisilane contained in the second liquid phase component derived from the tower bottom 3b of the second rectifying tower 3 can be taken out. High-purity disilane that has good operability and stability and is useful in semiconductor processes and the like can be taken out efficiently. In addition, with this configuration, for example, the column height is about 60 to 80 ° C., and the column height is about ½ to 10 ° C. can do.

  In the second configuration example, the mode in which high-purity disilane is extracted as the fourth gas phase component has been described. However, the present invention can be applied to a mode in which high-purity disilane is extracted as the liquid phase component (not shown). ) For example, the third separation tank 4a is set to about −10 to 0 ° C., the separation of trisilane and the like is completed in the second rectification column 3 and the third separation tank 4a, and the fourth separation tank 4b is set to about −30 to 30. By setting the temperature to −20 ° C., high-purity disilane can be taken out as a liquid phase component (fourth condensate). In addition, a part of the fourth condensate introduced into the upper introduction part 3d of the second rectification tower 3 via the flow path L13 can be taken out as high-purity disilane.

[Third configuration example of the apparatus]
As another configuration example of the present apparatus, in the above configuration example, as the first cold trap 2, a return flow path L7 that connects the tank bottom of the second separation tank 2b and the tank top of the first separation tank 2a, and a return flow path An apparatus using a configuration in which a feed pump 2c and a regulating valve 2d are provided in L7 is shown in FIG. 3 (third configuration example). By recirculating the second condensate derived from the second separation tank 2b to the first separation tank 2a, the large cold heat of the second condensate is utilized, and the energy efficiency is higher, and a plurality of silane compounds are separated and purified. In addition, by performing the separation process again in the first separation tank 2a, the yield of the low-order silane and the high-order silane can be increased while reducing the load on the first rectifying column 1.

  Specifically, the second condensate derived from the second separation tank 2b is returned to the first separation tank 2a via the return flow path L7, and the return flow rate is the feed provided in the return flow path L7. It is adjusted by the pump 2c and the regulating valve 2d. The flow rate control is performed using the return flow rate as an index of any one or some of monosilane, disilane, trisilane. The yield of desired low-order silane and high-order silane is adjusted by adjusting the extraction amount of the low-order silane in accordance with the composition of the silane compound in the raw material or its variation, and adjusting the separation function in the first separation tank 2a. Can be raised.

<Verification of the functions of this device>
In order to verify the superior functions of this device and this method, the structure and conditions of each part in this device and the device according to the prior art (hereinafter referred to as “conventional device”) for obtaining the same silane compound using the same raw material We also compared and verified the type and amount of refrigerant required.

[Verification conditions]
Silane compound A (hydrogen H ₂ 12 wt%, monosilane SiH ₄ 57 wt%, disilane Si ₂ H ₆ 22 wt%, trisilane Si ₃ H ₈ 9 wt%) and disilane as a main component as raw materials B (H ₂ 1 wt%, SiH ₄ 2 wt%, Si ₂ H ₆ 94 wt%, Si ₃ H ₈ 3 wt%) was prepared, and purification separation treatment was performed using disilane as the product gas and trisilane as the product liquid. The temperature, pressure and composition of each part (each flow path in FIG. 1) in both apparatuses were measured. As the refrigerant used for the first cold trap 2, only liquid nitrogen was used in the conventional apparatus, and liquid nitrogen was used only in the second separation tank in the present apparatus, and the consumption and power related to the cooling function at that time were measured. Also,

〔inspection result〕
(I) Comparison of the structure of the rectifying column A temperature gradient in the first rectifying column is set, and the apparatus at the column top temperature of -30 ° C and the conventional system at the column top temperature of -120 ° C under the condition of the column bottom temperature of 0 ° C. Table 1 shows the results of comparing the required tower heights using the tower diameter as an index for the apparatus. The result that this apparatus can obtain the same function at about 1/4 height of the conventional apparatus was obtained.

(Ii) Comparison of modes of each part of the apparatus The first rectification of both apparatuses using the present apparatus having a tower height of 3 mm and a conventional apparatus having a tower height of 12 m and silane compounds A and B as raw materials. Tables 2 and 3 show the temperature, pressure and composition of each flow path in the tower. In either case, in the composition of the condensate refluxed to the first rectification column via the flow path L5, the present apparatus obtained a result that the monosilane concentration was much lower and was effectively separated. Moreover, when hydrogen was contained in the raw material, in the conventional apparatus, the result that the hydrogen which is not yet isolate | separated was contained in the recirculated condensate was obtained. In any case, the present apparatus can reduce the load on the first rectification column. This result shows that it has an excellent function not only in the tower height but also in the rectification / separation treatment.

[Table 2] When silane compound A is used as a raw material

[Table 3] When silane compound B is used as a raw material

(Iii) Comparison of Electric Power Related to Cooling Function Containing Liquid Nitrogen Under this condition (ii), the present apparatus was compared with the conventional apparatus with respect to liquid nitrogen consumption, electric power related to the cooling function, and the like. The results are shown in Table 4. The results show that this apparatus has an excellent function of being very energy efficient and using a small amount of liquid nitrogen (a cryogenic refrigerant).
(Iii-1) The conventional apparatus needs to supply a cooling capacity of about 6.622 kW by liquefied nitrogen. The cooling capacity that can be collected per 1 Nm ³ / h of liquefied nitrogen was about 0.0970 kW, and about 68.3 Nm ³ / h of liquefied nitrogen was consumed. On the other hand, in this apparatus, the cooling capacity that needs to be supplied by liquefied nitrogen was about 3.998 kW. About 41.2 Nm ³ / h of liquefied nitrogen was consumed. From the above, it was obtained that this apparatus can reduce the consumption of liquefied nitrogen of about 27.1 Nm ³ / h compared to the conventional apparatus.
(Iii-2) Moreover, in this apparatus, in order to cool to -30 degreeC in a 1st separation tank, about 2.624 kW cooling capacity (brine) is needed with a refrigerator. Therefore, not only the consumption of liquefied nitrogen but also the energy required for the cooling process of both devices is converted into electric power and compared. That is, the amount of liquefied nitrogen consumed and the power required to obtain the cooling capacity of the separation tank (cooler) are compared.
About 0.526 kWh / Nm ³ is required for the liquefaction basic unit necessary for converting nitrogen gas into liquefied nitrogen. On the other hand, in order to obtain a cooling capacity of 1 kW by the refrigerator, about 0.956 kW of electric power is required.
(Iii-3) From the above, in order to obtain the cooling capacity required in the conventional apparatus,
^{68.3 [Nm 3 /h]×0.526[kWh/Nm 3] =} 35.9 [kW]
Is required.
On the other hand, in order to obtain the required cooling capacity in this device,
^{41.2 [Nm 3 /h]×0.526[kWh/Nm 3] (} = 21.7)
+2.624 [kW] × 0.956 [kW / kW] (= 2.51)
= 24.2 [kW]
Is required.
Therefore, the total amount of power to be reduced is about 11.7 kW (−33% based on the conventional apparatus).

DESCRIPTION OF SYMBOLS 1 1st purification tower 1a, 3a Tower top part 1b, 3b Tower bottom part 1c, 1d, 3c Introduction part 1e, 3e Middle 1r, 3r Reboiler 2 1st cold trap 2a 1st separation tank 2b 2nd separation tank 3 2nd refinement Toru tower 4 Second cold trap 5 Coolers L1 to L11 Flow path

Claims (6)

At least a first rectifying column into which a raw material containing a plurality of fed silane compounds is introduced, and a first gas phase component containing a low-order silane derived from the top of the first rectifying column are introduced. A first cold trap which is cooled and gas-liquid separated, and a second rectifying column into which a first liquid phase component mainly composed of higher order silane derived from the bottom of the first rectifying column is introduced. And a second cold trap into which the second gas phase component derived from the top of the second rectification column is introduced, cooled and gas-liquid separated, and
The first cold trap has at least a first separation tank and a second separation tank, and is composed of a plurality of stages of separation tanks whose set temperatures are successively reduced, and is derived from the first separation tank and the second separation tank. And the introduced first condensate and second condensate are introduced into the upper stage of the first rectifying column,
Monosilane contained in the third gas phase component derived from the first cold trap is taken out, disilane contained in the fourth gas phase component derived from the second cold trap is taken out, and the tower of the second rectification column An apparatus for producing a silane compound, wherein trisilane contained in the second liquid phase component derived from the bottom is taken out.   The introduction part of the second condensate derived from the second separation tank to the first rectification column is the introduction part of the first condensate derived from the first separation tank to the first rectification tower. The apparatus for producing a silane compound according to claim 1, wherein the apparatus is disposed in an upper stage.   A pre-cold trap is provided in a flow path through which the raw material is introduced into the first rectification column, and brine is used as a refrigerant supplied to the pre-cold trap, the first separation tank, and the second cold trap, The apparatus for producing a silane compound according to claim 1 or 2, wherein a cryogenic refrigerant such as liquid nitrogen or methanol / dry ice is used as the refrigerant supplied to the second separation tank.   The return flow path which connects the tank bottom part of the said 2nd separation tank and the tank top part of the said 1st separation tank, A feed pump and an adjustment valve are provided in this return flow path, The characterized by the above-mentioned. The manufacturing apparatus of the silane compound in any one. A method for producing a silane compound, comprising at least the following steps using the apparatus for producing a silane compound according to claim 1.
(1) The fed raw material containing a plurality of silane compounds is introduced into the first fractionator,
(2) First rectification is carried out in the first rectification column, a first gas phase component containing low-order silane is led out from the top of the first rectification column, and the first main component containing high-order silane from the bottom of the column. The liquid phase component is derived,
(3) The first gas phase component is introduced into a first cold trap that includes at least a first separation tank and a second separation tank, and is composed of a plurality of stages of separation tanks whose set temperatures are successively reduced,
(3-1) Cooled and gas-liquid separated in the first cold trap, the third gas phase component is derived,
(3-2) The first condensate and the second condensate derived from the first separation tank and the second separation tank are derived,
(3-3) The first condensate and the second condensate are introduced into the upper stage of the first rectifying column,
(4) The first liquid phase component is introduced into the second rectification column,
(5) rectification is performed in the second rectification column, the second gas phase component is derived from the top of the second rectification column, and the second liquid phase component is derived from the bottom of the column,
(6) The second gas phase component is introduced into the second cold trap,
(7) Cooled and gas-liquid separated in the second cold trap, the fourth gas phase component is derived,
(8) Monosilane contained in the third gas phase component is taken out, disilane contained in the fourth gas phase component is taken out, and trisilane contained in the second liquid phase component is taken out.   A part or all of the second condensate is returned to and introduced into the first separation tank, and the return flow rate is controlled by using one or some of the extracted amounts of monosilane, disilane, or trisilane as an index. The method for producing a silane compound according to claim 5, wherein:

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