CN115947317A - System and method for preparing trisilylamine - Google Patents
System and method for preparing trisilylamine Download PDFInfo
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- CN115947317A CN115947317A CN202211272173.XA CN202211272173A CN115947317A CN 115947317 A CN115947317 A CN 115947317A CN 202211272173 A CN202211272173 A CN 202211272173A CN 115947317 A CN115947317 A CN 115947317A
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Abstract
The invention discloses a system and a method for preparing trisilylamine. The method takes monochlorosilane and liquid ammonia as raw materials, a contact interface is formed in a reactor by adopting a solvent and the liquid ammonia, and the monochlorosilane dissolved in the solvent and the liquid ammonia react at the contact interface to generate the trisilylamine. The invention designs a two-phase reaction system, provides a reaction interface of substances, controls the substances to participate in the reaction at the interface, can avoid local heat effect, can effectively control the reaction process, can realize the physical isolation of the by-product ammonium chloride and the trisilylamine, has less side reaction, and can avoid the reduction of the product yield caused by the catalysis of the by-product ammonium chloride on the decomposition of the trisilylamine.
Description
Technical Field
The invention relates to the technical field of trisilylamine preparation, in particular to a system and a method for preparing trisilylamine.
Background
Trisilylamine ((SiH) 3 ) 3 N, TSA) is a highly volatile silicon source precursor material. Because it has the advantages of no carbon, no chlorine and strong volatility, the introduction of carbon can be reduced to the utmost extent and solid NH in the deposition process can be avoided 4 The formation of Cl byproducts, which can improve the process and performance of silicon nitride (SiNx) films grown using Atomic Layer Deposition (ALD), is one of the high dielectric constant materials for depositing ALD silicon nitride films.
At present, trisilylamine is mainly synthesized by reacting monochlorosilane with ammonia, and the synthesis method is mainly divided into liquid phase and gas phase. The reaction equation is shown in (1) below:
3SiH 3 Cl+4NH 3 →(SiH 3 ) 3 N+3NH 4 Cl (1)
wherein the reaction is completed by three steps, which are respectively shown in the following (2), (3) and (4):
chinese application CN 103608287A discloses a gas phase synthesis method, firstly, dihalogen silicane and monosilane are adopted to react to obtain Monohalosilane (MCS); then, directly mixing the ammonia with raw material ammonia by a mixer, introducing the mixture into a reactor in a gaseous state, controlling the temperature of the reactor to be 380-450 ℃ to form a product mixture containing trisilylamine, ammonium halide and ammonia; the product mixture is then removed from the reactor as a gaseous mixture, separated, filtered, and purified by distillation to give the product. The process belongs to a gas-phase synthesis method, the flow is simpler, but the temperature of a reactor is higher; in addition, the raw material preparation process relates to silane and dihalosilane, so that the danger coefficient is higher, the investment cost of subsequent industrial preparation equipment and the like is higher, and the large-scale production is difficult; in addition, the dihalogen silicane and the monosilane react to obtain a mixture, other chlorosilane in the mixture can also react with the raw material ammonia, the product is complex, the number of byproducts is large, the separation difficulty is high, and the purification to a high-purity product is difficult.
Chinese application CN108586515a discloses a gas phase synthesis method, which adopts a catalytic distillation tower for preparation, reactants monochlorosilane and ammonia continuously enter the catalytic distillation tower from a rectification section and a stripping section in a gaseous form for reaction, and self-made filler is filled in the reaction section, the molar ratio of MCS to ammonia is 1.2-3, the reaction pressure is 0.2-1 MPa, the reaction temperature in the tower is 350-420 ℃, and NH is separated from the tower bottom 4 And Cl, and then obtaining the high-purity TSA through a known impurity removal and purification technology. NH formed during the reaction 4 Cl is a solid, and the contents in the column are easy to block fillers, pipelines and the like, so that the reaction is difficult to continuously run.
The Chinese application CN106659999A discloses a method for trisilylamine, aiming at a byproduct ammonium chloride, the improvement principle is as follows: excessive ammonia is introduced to prevent monochlorosilane at the downstream of the equipment from reacting with other small-amount formed disilylamine to generate ammonium chloride, so that the generation of ammonium chloride as a byproduct in the equipment is reduced. The method adopts a reaction synthesis-rectification purification mode to prepare the high-purity TSA; specifically, the MCS and toluene mixed solution is firstly mixed(MCS/toluene solvent volume ratio = 3-10) and ammonia (content of 0.5-5% excess (mol)) are conveyed into a reactor, and stirring reaction is carried out for 1h at the temperature of 10-30 ℃ and the pressure of 0.05-0.08 MPa to form a mixture containing TSA and solid NH 4 A mixture of Cl; the mixture is then passed through a filter at the bottom of the reactor to separate off the solid NH 4 Cl; the reactor is then depressurized to 0.5 b-0.8 bar, the reactor is heated and the product mixture (TSA, toluene, NH) 4 Cl, dimethylsilalkylamines DSA, NH 3 ) Flowing out in gaseous form; NH 3 After condensation, the condensed liquid returns to the reactor for reuse, the mixture filtrate containing DSA and TSA is conveyed to a light component removal and heavy component removal rectifying tower for purification, and the purity of the TSA product reaches 99.5 percent.
The inventors of the present application have found that the following problems may occur in some of the prior arts including the above: 1) Silane and dihalo-silane are used as raw materials to synthesize monochlorosilane, the synthesized product is a mixture and is subjected to mixing reaction with ammonia without separation, and the reaction product contains a plurality of byproducts, which is not beneficial to the preparation of final products. 2) Chlorosilane and ammonia are easy to react, and the reaction will be carried out in the mixing step, so that the problems of blockage of a mixer and the like can be caused. 3) In addition, when a gas phase reaction is adopted, the temperature required by the reaction is high and exceeds 300 ℃, the reaction conditions are harsh, the process is not easy to control, the synthesized product can be further polymerized, a plurality of byproducts are generated, the product quality is influenced, and the yield of the material is low. 4) When a liquid phase reaction is adopted, the reaction is violent, the stirring and mixing are mostly carried out by adopting a bubbling or dropping mode, the reaction interfaces are more, the local heat effect can be generated, the process is not easy to control, the substances are polymerized, and the byproducts are more. 5) During the reaction, ammonium chloride generated as a byproduct catalyzes the decomposition of trisilylamine, thereby reducing the product yield. Therefore, it is highly desirable to provide a new process for preparing trisilylamine.
Disclosure of Invention
According to one embodiment of the present invention, it is an object to provide a system and method for preparing trisilylamine. According to the implementation mode, a two-phase reaction system is designed, a reaction interface of a substance is provided, the two substances are limited to participate in the reaction at the interface, the local heat effect can be avoided, the reaction process can be effectively controlled, the side reaction is less, the physical isolation of the by-product ammonium chloride and the trisilylamine is realized, and the decomposition of the trisilylamine by the by-product ammonium chloride is avoided, so that the product yield is reduced.
The above object can be achieved by the following embodiments of the technical solutions:
according to one aspect of the invention, the invention provides a method for preparing trisilylamine, which takes monochlorosilane and liquid ammonia as raw materials, forms a contact interface in a reactor by adopting the solvent and the liquid ammonia, feeds the monochlorosilane into the solvent in the reactor, stirs the solvent in a stirring manner parallel to the contact interface, and reacts the monochlorosilane dissolved in the solvent with the liquid ammonia at the contact interface to generate the trisilylamine. In addition, the by-product ammonium chloride generated by the reaction is dissolved in the liquid ammonia or floats on the upper liquid level of the liquid ammonia, so that the physical isolation from the trisilylamine is realized.
Optionally, forming a contact interface in the reactor with a solvent and liquid ammonia, comprising: controlling reactor temperature and pressure; adding solvent and liquid ammonia into reactor in turn, making liquid ammonia and solvent be distributed vertically in the reactor, and forming a contact interface at the contact position of liquid ammonia and solvent.
Optionally, the temperature of the reactor is controlled to be-60 ℃ to 30 ℃, and the pressure is controlled to be-100 kPa to 1200kPa.
Optionally, the method further comprises: according to the adding amount of liquid ammonia in the reactor, the concentration of the monochlorosilane in the solvent is controlled by controlling the feeding amount of the monochlorosilane, so that the reaction degree of the monochlorosilane and the liquid ammonia on a contact interface is controlled.
Alternatively, the molar ratio of the total charge of monochlorosilane to liquid ammonia in the reactor is from 1 to 1.3.
Optionally controlling the amount of monochlorosilane to 5-20% by weight of the amount of solvent.
Optionally, when stirring, the stirring paddle is horizontally rotated at the rotating speed of 40 r/min-60 r/min;
optionally, the solvent is selected from one or more of alkanes, cycloalkanes, aromatics.
Optionally, the solvent is one or more of pentane, hexane, cyclohexane, heptane, octane, benzene, and toluene.
Optionally, after the reaction is completed, the method further comprises: sending into a filter for filtering, and separating ammonium chloride from solid and liquid; sending the liquid phase after solid-liquid separation into a primary separation tower for separation, and returning the solvent at the bottom of the tower after separation to the reactor for recycling; feeding the separated tower top material into a refining tower for rectification separation to obtain a trimethylsilyl product;
optionally, when the primary separation tower is used for separation, the pressure at the top of the tower is controlled to be 10 kPa-1000 kPa; and during rectification separation, controlling the pressure at the top of the tower to be 10 kPa-1000 kPa.
Optionally, the rectification column is a dividing wall rectification column. Optionally, the trisilylamine product has a trisilylamine purity of no less than 99.5%.
According to another aspect of the present invention, the present invention provides a system for preparing trisilylamine, comprising a reactor, wherein the reactor comprises a feed inlet, a feed inlet and a stirrer; the charge door is arranged as follows: adding solvent and liquid ammonia to form a contact interface in the reactor; the feed inlet is arranged as follows: feeding monochlorosilane directly into a solvent in a feeding manner; the agitator is arranged to agitate the solvent to dissolve the monochlorosilane in the solvent without disrupting the contact interface, such that the monochlorosilane in the solvent is constrained to react with the liquid ammonia at the contact interface to form trisilylamine, and such that the by-product ammonium chloride dissolves in the liquid ammonia or floats above the liquid ammonia at a level that is physically separate from the trisilylamine.
Alternatively, a system for preparing trisilylamine, the system comprising: a reactor, comprising: the device comprises a feed inlet, a stirrer and a control assembly; wherein the control assembly is used for controlling the temperature and the pressure in the reactor; the addition port, at least one, is used for adding solvent and liquid ammonia to the reactor, and the addition port is arranged as follows: after the solvent and the liquid ammonia are added, a contact interface is formed at the contact liquid level between the solvent and the liquid ammonia; the feed inlet is used for feeding monochlorosilane into the solvent in the reactor; the stirrer is fixed in the reactor and is positioned in the solvent, and is used for stirring the solvent in a stirring mode parallel to a contact interface in the feeding process, so that monochlorosilane is dissolved in the solvent, the monochlorosilane dissolved in the solvent and liquid ammonia react at the contact interface to generate trisilylamine, and the by-product ammonium chloride is dissolved in the liquid ammonia or floats on the upper liquid level of the liquid ammonia to realize physical isolation from the trisilylamine.
Optionally, the feed port is located at the upper part of the reactor, and the solvent and the liquid ammonia are added sequentially. Optionally, one end of the stirrer is a stirring paddle, and the other end of the stirrer is fixed at the upper part of the reactor; the feed inlet is located in the lower part of the reactor and is lower than the reaction contact interface.
Optionally, the reactor is provided with a jacket, and a cooling medium is introduced into the jacket and used for adjusting the temperature in the reactor through heat exchange.
Optionally, a flow valve is arranged at the feed port and used for controlling the feed amount of the monochlorosilane.
Optionally, the system further comprises: a filter, a primary separating tower and a refining tower which are connected in sequence. Further, the filter is connected with the reactor and used for filtering reaction products, separating solid and liquid from solid ammonium chloride, and sending the liquid phase after solid and liquid separation into a primary separation tower; the primary separation tower comprises an inlet, a tower bottom solvent outlet and a tower top material outlet, wherein the inlet is connected with the filter, the tower top material outlet is connected with the refining tower, and the tower bottom solvent outlet is connected with the reactor and is used for returning the separated solvent to the reactor for recycling; and the refining tower is used for receiving the material separated by the primary separation tower, and performing rectification separation to obtain a trisilylamine product.
Optionally, the top pressure of the primary separation tower is 10 kPa-1000 kPa; the top pressure of the refining tower is 10 kPa-1000 kPa; the refining tower is a dividing wall rectifying tower.
Has the advantages that: according to one embodiment of the invention, monochlorosilane and liquid ammonia are used as raw materials, a two-phase reaction system is designed, a reaction interface of the materials is provided, the two materials participate in the reaction at the interface, the local heat effect can be avoided, the process control can be effectively carried out, the side reaction is less, the physical isolation of the by-product ammonium chloride and the trisilylamine is realized, and the problem of product yield reduction caused by the catalysis of the by-product ammonium chloride on the decomposition of the trisilylamine is avoided.
In addition, in some preferred embodiments, through further improvement, closed cycle of materials is realized, and trisilylamine with high purity can be prepared.
Drawings
FIG. 1 is a schematic flow diagram of a process for preparing trisilylamine in one embodiment of this invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for preparing trisilylamine, which takes monochlorosilane and liquid ammonia as raw materials, adopts solvent and liquid ammonia to form a contact interface in a reactor, feeds the monochlorosilane into the solvent, stirs the monochlorosilane to dissolve the monochlorosilane, and leads the monochlorosilane dissolved in the solvent to react with the liquid ammonia at the contact interface to generate the trisilylamine. By designing a two-phase reaction system, a reaction interface of substances is provided, the two substances participate in the reaction at the reaction interface, and the reaction interface is reduced (compared with the conventional bubbling, dripping or direct stirring and mixing mode), so that the local heat effect is avoided, the process control can be effectively carried out, the side reaction is less, and meanwhile, the by-product ammonium chloride generated by the reaction can be dissolved in the liquid ammonia or float on the upper liquid level of the liquid ammonia, so that the by-product ammonium chloride and the trisilylamine are physically isolated, the side reaction is less, the decomposition of the trisilylamine by the by-product ammonium chloride is avoided, and the product yield is ensured.
It should be noted that: the "two phases" mentioned above in the present application means two phases of liquid ammonia and solvent liquid which are not dissolved into each other, and the two phases have different densities, and are layered up and down, so that a contact interface is formed where the two phases contact each other, and the contact interface is used as a reaction interface of the substance. The solvent is an organic solvent which can dissolve the monochlorosilane and is immiscible with the liquid ammonia.
FIG. 1 schematically shows a flow of a method for preparing trisilylamine in one embodiment. The system and method for preparing trisilylamine in this example are further illustrated in conjunction with FIG. 1.
The system for preparing trisilylamine in the embodiment comprises a reactor, a filter, a primary separation tower and a refining tower which are connected in sequence. Wherein, the primary separation tower is also connected with the reactor so as to return the separated solvent to the reactor for recycling. The reactor comprises a feed inlet, an agitator, and a control assembly for controlling the temperature and pressure of the reactor, wherein the feed inlet and feed inlet are arranged to carry out the above process. Further, in the reactor, the charging port is arranged as follows: adding solvent and liquid ammonia through a feed inlet, and enabling the solvent and the liquid ammonia to form a contact interface in the reactor; the feed inlet is arranged as follows: monochlorosilane is fed directly into the solvent through the feed port in a continuous feed manner to be dissolved by stirring and to be reacted with liquid ammonia at the contact interface to produce trisilylamine.
In the method for preparing trisilylamine in the embodiment, monochlorosilane and liquid ammonia are used as raw materials, one or more of alkane, cycloalkane and aromatic hydrocarbon are used as a solvent, for example, one or more of pentane, hexane, cyclohexane, heptane, octane, benzene, toluene and the like are used, a contact interface is formed at the contact liquid level of the solvent and the liquid ammonia, the contact interface is used as a reaction interface, the two raw materials are limited to participate in the reaction at the reaction interface, the process control is effectively carried out, the physical isolation of a by-product ammonium chloride and the trisilylamine is realized, the side reaction is less, and the product yield is ensured; meanwhile, the closed cycle of the materials is carried out to prepare the trisilylamine with high purity. Specifically, the following steps may be included:
step S1, controlling the temperature and the pressure of the reactor, wherein the temperature of the reactor is-60-30 ℃, and the pressure is-100 kPa-1200 kPa. Controlling the reaction environment through the conditions, wherein the temperature control can ensure that the ammonia is in a liquid state, so that an insoluble liquid-liquid two phase is continuously formed with the solvent to provide a reaction interface and limit the reaction to be carried out at the reaction interface; and the pressure control can realize the regulation of the temperature in the reactor, control the ambient temperature during the reaction, improve the reaction efficiency and realize the energy-saving effect. The reaction of monochlorosilane and liquid ammonia belongs to a strong exothermic reaction, the reaction environment in a reactor needs to be ensured in the reaction process, the reaction is mainly realized through a control assembly, the specific form of the control assembly is not limited, and the temperature and the pressure are ensured to be within the range. For temperature control, for example, the reactor may be provided with a jacket, a coolant is introduced into the jacket, and the coolant in the jacket exchanges heat to take away reaction heat, thereby ensuring a temperature environment in the reactor and ensuring the reaction. In addition, the temperature environment in the reactor can be adjusted by controlling the addition amount or speed of the monochlorosilane (i.e., controlling the reaction), so as to ensure that the monochlorosilane is maintained in the above range, thereby controlling the reaction only at the contact surface and the degree of reaction progress at the contact surface. Meanwhile, the reaction controllability of the method is reflected, and the effect cannot be realized by an all-dimensional mixing mode (such as directly dissolving monochlorosilane in a solvent).
The method controls the temperature and the pressure of the reaction environment, and simultaneously controls the continuous feeding of the monochlorosilane and the feeding amount/speed thereof, so that the reaction is controllable (not only including limiting the reaction to be carried out only at the contact plane of two phases, but also including controlling the proceeding degree of the reaction at the contact plane); moreover, only the adjustment of the amount is needed, and the reaction control is easier to realize.
S2, adding a solvent into the reactor, so that the liquid level of the solvent exceeds the upper edge of a stirring paddle of the stirrer; liquid ammonia is added into the reactor from the top of the reactor, a contact interface is formed at the contact liquid level of the liquid ammonia and the solvent, and the contact interface is used as a reaction interface of the monochlorosilane and the liquid ammonia. Wherein, liquid ammonia and solvent which have density difference and are not mutually dissolved are adopted to form a contact interface which is approximate to a plane; the solvent may dissolve monochlorosilane; the liquid ammonia is easy to vaporize, and is ensured to be in a liquid state through the temperature and the pressure in the reactor, so that the continuous formation and maintenance of a contact interface are ensured.
And S3, controlling the flow of the monochlorosilane, feeding the monochlorosilane into the solvent, starting a stirrer in the feeding process to stir the solvent in a manner of rotating parallel to a contact interface, dissolving the monochlorosilane into the solvent, and enabling the solvent in which the monochlorosilane is dissolved to flow in the stirring process, so that the monochlorosilane dissolved in the solvent and liquid ammonia react at a reaction interface to produce a reaction product containing trisilylamine, ammonium chloride and the like.
In the step, monochlorosilane is added into the solvent in a feeding mode and dissolved in the solvent, rather than directly dissolving all monochlorosilane in the solvent, the feeding mode enables the reaction to be controllable, and the problems of by-product generation caused by local heat effect due to violent reaction and the like are avoided; and monochlorosilane dissolved in the solvent is limited at the contact interface to react with liquid ammonia, so that the reaction interface is reduced, and the reaction is further controllable; and monochlorosilane in the raw materials is added in a feeding mode, and liquid ammonia at a reaction interface keeps excessive locally, so that TSA is generated.
The stirring paddle of the stirrer is positioned in the solvent when the monochlorosilane is fed, and the solvent is stirred in a horizontal rotating mode, so that the monochlorosilane is fully dissolved and a contact interface is not damaged; the solvent dissolved with the monochlorosilane flows during the stirring process, so that the reaction of the monochlorosilane dissolved in the solvent and the liquid ammonia at the contact interface is continuously, stably and orderly carried out. The arrangement mode of the stirrer in the reactor is used for realizing the functions, improving the stirring uniformity and carrying out the setting for the purpose of orderly carrying out the reaction. For example, it may be preferable to arrange it at the central axis of the reactor, ensuring that the dissolution and reaction proceed uniformly. More specifically, one end of the stirring paddle can extend into the lower part of the reactor and be horizontally arranged in the flux to avoid the solvent from moving vertically to break a reaction interface, and the other end of the stirring paddle is fixed with the reactor, can be fixed on the upper part of the reactor and can also be fixed on the lower part of the reactor.
The feed inlet is used for feeding monochlorosilane, is arranged at the lower part of the reactor and is lower than the reaction interface so as to ensure that the monochlorosilane is fed into the solvent, thus being beneficial to dissolution and effectively carrying out reaction at the reaction interface. Furthermore, the height of the feeding hole can be lower than that of the stirring paddle, so that the raw materials are fully diluted and dissolved in the solvent, and monochlorosilane dissolved in the solvent at a contact interface is distributed more uniformly, thereby being more beneficial to the stable and orderly proceeding of subsequent reactions and being easier to control the reactions.
In addition, a flow valve is arranged on the pipeline at the feed inlet, and the feed amount of the monochlorosilane is controlled by controlling the flow of the monochlorosilane in the pipeline. Furthermore, according to the addition of liquid ammonia in the reactor, the concentration of the monochlorosilane in the solvent is controlled by controlling the feeding amount of the monochlorosilane, so that the reaction degree of the monochlorosilane and the liquid ammonia on a contact interface is controlled, and the effective control of the reaction process is further realized.
In an alternative embodiment, the amount of monochlorosilane can be controlled by 5 to 20%, preferably 10 to 15%, of the amount of solvent, by which the heat of reaction can be effectively controlled, the occurrence of local overheating conditions being avoided. Furthermore, the reaction time can be controlled to be 0.5 h-10 h, the reaction heat is further controlled, and the occurrence of local overheating is avoided.
In addition, in the feeding process, the stirring speed is controlled to be 40 r/min-60 r/min, and the mixing effect of the monochlorosilane and the solvent can be ensured and the stability of a reaction interface can be kept in the range; if the stirring speed is too high, the reaction interface fluctuates greatly, which destroys the established reaction interface and is not favorable for reaction control.
And further, according to the amount of liquid ammonia in the reactor, continuously introducing monochlorosilane, completely consuming the amount of liquid ammonia, wherein the molar ratio of monochlorosilane to liquid ammonia integrally added into the reactor is 1-1.3. Under the proportion range, the total amount of liquid ammonia is not excessive, but the liquid ammonia in the reaction interface is kept excessive locally due to the adoption of a feeding mode of monochlorosilane, so that the generation of TSA is facilitated; through continuously introducing the monochlorosilane, all the liquid ammonia can be finally and completely consumed, so that the subsequent separation operation is more favorably carried out, and the product purity and the utilization rate of raw materials are improved.
The reaction principle in the reactor is as follows:
the method comprises the steps of feeding and dissolving monochlorosilane in a solvent, wherein the solvent is one or a mixture of several of pentane, hexane, cyclohexane, heptane, octane, benzene, toluene and the like, the monochlorosilane is fully diluted by the solvent, the monochlorosilane dissolved in the solvent is in contact reaction with liquid ammonia on a contact surface at the position of the contact interface, the concentration of the monochlorosilane in the solvent is further controlled by controlling the adding amount of the monochlorosilane, the reaction of the monochlorosilane and ammonia is further controlled, the reaction is limited at the position of the contact liquid surface, and therefore the control of the reaction can be achieved, and the generation of byproducts caused by local thermal effects due to violent reaction is avoided.
The ammonium chloride generated by the reaction is solid and has a certain catalytic action, and in the presence of the ammonium chloride, the decomposition and disproportionation of the product trisilylamine into silane and other decomposed substances can be catalyzed.
And S4, after the reaction is finished, feeding the reaction product into a filter for filtering, carrying out solid-liquid separation on solid-phase ammonium chloride, a solvent, trisilylamine, disilylamine, excessive monochlorosilane and the like, and feeding the liquid-phase substance subjected to solid-liquid separation into a primary separation tower.
And S5, controlling the top pressure of the primary separation tower to be 10-1000 KPa, extracting trisilylamine, disilyldialkylamine, excessive monochlorosilane and the like from the top of the primary separation tower to enter a refining tower, and extracting a solvent from the bottom of the primary separation tower to return the solvent to the reactor for recycling.
And S6, controlling the top pressure of the refining tower to be 10-1000 KPa, feeding the material extracted from the top of the primary separation tower into the refining tower, and performing rectification separation. Rectification and separation: extracting low-boiling-point substances such as dimethyl silyl amine, monochlorosilane and the like from the top; the trisilylamine product is extracted from the middle part, the product component is not less than 99.5 percent, usually more than 99.9 percent, and the yield is more than 80 percent; and extracting trace amount of solvent, polymer and other high boiling point matter in the tower. Wherein, the refining tower is a dividing wall rectifying tower, and can ensure the purity of the product.
In the embodiment, a two-phase reaction system is designed, a contact interface formed by a solvent and liquid ammonia is used as a reaction interface of substances, monochlorosilane is added in a feeding mode, the solvent is stirred to be dissolved in the reaction interface, and only the two substances participate in the reaction at the interface, so that the process control is effectively carried out, the side reaction is less, meanwhile, the by-product ammonium chloride and the trisilylamine are physically isolated, the side reaction is less, and the closed cycle of the materials is carried out, so that the high-purity trisilylamine is prepared.
Compared with the prior art, the application has at least the following advantages and beneficial effects:
1) Monochlorosilane and liquid ammonia are used as raw materials, pentane, hexane, cyclohexane, heptane, octane, benzene, toluene and the like are used as solvents, a reaction interface of substances is provided through the design of the liquid ammonia and the solvents, the reaction is limited at the reaction interface, the two substances participate in the reaction at the reaction interface, the process control can be effectively carried out, and the side reaction is few.
2) Through the design of a two-phase system, the ammonium chloride generated by the reaction is physically isolated from the generated target product of trisilylamine, the contact with trisilylamine in a solvent is avoided/reduced, the decomposition of the trisilylamine is avoided, the yield of the product is higher, and the quantity and the types of byproducts are fewer. Meanwhile, most of the ammonium chloride generated by the method floats on the upper surface of the liquid ammonia (a small part of the ammonium chloride is dissolved in the liquid ammonia), so that the problem that the reaction is difficult to continuously run due to the blockage of fillers, pipelines, inlets and outlets and the like caused by the generation of solid ammonium chloride in the conventional gas phase synthesis method is solved.
3) Compared with a mode of dissolving monochlorosilane in a solvent in advance and stirring and mixing the monochlorosilane with ammonia (a reaction interface can not be formed in the application), the monochlorosilane is fed in a feeding mode and dissolved in the solvent, the monochlorosilane is fully diluted, and the monochlorosilane dissolved in the solvent and liquid ammonia are limited to only have contact reaction at a contact surface instead of all-around mixing, so that the reaction is controllable and easy to control, and the thermal runaway of the reaction is avoided; furthermore, continuous feeding allows the liquid ammonia at the reaction interface to be kept locally excessive, which is more favorable for TSA generation.
Compared with the prior art, the method has the following advantages and beneficial effects in some embodiments:
4) The reaction of monochlorosilane and liquid ammonia belongs to a strong exothermic reaction, the concentration of monochlorosilane in a solvent is controlled by controlling the adding amount or speed of monochlorosilane, for example, the content of monochlorosilane can be controlled by 5-20 wt% of the solvent, and further the reaction degree of monochlorosilane and ammonia at the contact surface is controlled, so that the reaction can be more effectively controlled, and the problem of by-product generation caused by local heat effect due to violent reaction is avoided.
5) And controlling the molar ratio of monochlorosilane to liquid ammonia in the reactor as 1-1.3. According to the amount of liquid ammonia in the reactor, monochlorosilane is continuously introduced, the amount of liquid ammonia is completely consumed, and the liquid ammonia is kept excessive from the beginning of the reaction to the completion of the consumption of the liquid ammonia at a reaction interface, so that the generation of TSA is facilitated, and the generation of byproducts such as monosilylamine and disilylamine is reduced; the liquid ammonia is not excessively consumed completely by continuously feeding the monochlorosilane, so that the subsequent separation operation is more facilitated.
6) Through further improvement, the product after reaction is subjected to solid-liquid separation, primary separation in a tower (and solvent return), rectification separation and closed cycle of materials, so that the trisilylamine with high purity is prepared. Wherein, the solvent is separated and recycled by arranging a primary separation tower.
7) The refining column is preferably a dividing wall rectifying column. Feeding from a column; low boiling point substances such as dimethyl siloxane, monochlorosilane and the like are extracted from the top; the trisilylamine product is extracted from the middle part, the product component is more than 99.9 percent, and the yield is more than 80 percent; trace amount of high boiling point substances such as solvent, polymer and the like are extracted from the tower kettle. One tower realizes the separation of various substances, and the number of rectifying towers is reduced.
The above embodiments of the present application will be described in more detail with reference to the following specific examples:
example 1
1) The temperature of the reactor was controlled at-30 ℃ and the pressure 100KPa. N-hexane was added to the reactor at a level above the upper edge of the stirrer. Liquid ammonia is added into the reactor from the top of the reactor, a contact interface is formed at the contact position of the liquid ammonia and the solvent, the contact interface is used as a reaction interface, and the subsequent reaction is limited to be carried out at the contact interface.
2) Feeding monochlorosilane into a solvent continuously in a feeding mode from the lower part of a reactor to a position lower than a reaction interface, starting a stirrer to enable a stirring paddle to rotate horizontally to stir the solvent, enabling the monochlorosilane to be dissolved into the solvent at a rotating speed of 50r/min, and enabling the monochlorosilane dissolved in the solvent to react with liquid ammonia at the reaction interface to produce trisilylamine, ammonium chloride and the like; wherein, the generated ammonium chloride is solid, one part is dissolved in the liquid ammonia, and the other part floats on the upper liquid level of the liquid ammonia, thereby avoiding/reducing the contact between the generated trisilylamine and the ammonium chloride, avoiding the decomposition of the trisilylamine, having higher product yield and less quantity and types of byproducts. Further, monochlorosilane is continuously introduced into the reactor in an amount such that the amount of monochlorosilane in the solvent is within a range of from 10 to 15% by weight, the amount of liquid ammonia is completely consumed, the molar ratio of monochlorosilane to liquid ammonia as a whole fed into the reactor is 1:1, and the reaction time is 2 hours.
3) After the reaction is finished, conveying the reaction product into a filter for filtering, and carrying out solid-liquid separation on ammonium chloride, a solvent, trisilylamine, disilylamine, excessive monochlorosilane and the like; and (4) feeding the liquid phase substance after solid-liquid separation into a primary separation tower for separation. Controlling the top pressure of the primary separation tower to be 100KPa, collecting trisilylamine, disilylamine, excessive monochlorosilane and the like from the top of the primary separation tower, and feeding the trisilylamine, disilylamine, excessive monochlorosilane and the like into a refining tower; and extracting the solvent from the bottom of the primary tower, and returning the solvent to the reactor for recycling. The refining tower is a dividing wall rectifying tower, the top pressure of the refining tower is controlled to be 100KPa, materials extracted from the top of the primary separating tower are fed from the tower, low boiling point substances such as disilylamine, monochlorosilane and the like are extracted from the top of the primary separating tower, trisilylamine products are extracted from the middle of the primary separating tower, and the product components are 99.5%. The yield is 82 percent, and trace high boiling point substances such as solvent, polymer and the like are extracted from the tower bottom.
Example 2:
the other conditions were the same as in example 1, and the reactor temperature was adjusted to-20 ℃ and the pressure to 100KPa. The product component is more than 99.7 percent. The yield thereof was found to be 86%.
Example 3:
otherwise, the reaction was carried out in the same manner as in example 1, and toluene was used as the reaction solvent. The product component is more than 99.5 percent. The yield thereof was found to be 83%.
Example 4:
the other conditions were the same as in example 1, and the reaction time was adjusted to 3 hours. The product component is more than 99.9 percent. The yield thereof was found to be 87%.
Example 5:
the other conditions were the same as in example 1, and the reaction time was adjusted to 4 hours. The product component is more than 99.9 percent. The yield thereof was found to be 87%.
Example 6:
the other conditions were the same as in example 1, the molar ratio of monochlorosilane to liquid ammonia fed to the reactor was adjusted to 1.2, and the reaction time was 4 hours. The product component is more than 99.9 percent. The yield thereof was found to be 85%.
The description of the present invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.
Claims (14)
1. A process for preparing trisilylamine, characterized in that monochlorosilane and liquid ammonia are used as raw materials, monochlorosilane is fed into a solvent in a reactor by forming a contact interface in the reactor using the solvent and the liquid ammonia, the solvent is stirred in a manner parallel to the contact interface to dissolve the monochlorosilane, the monochlorosilane dissolved in the solvent reacts with the liquid ammonia at the contact interface to form trisilylamine, and ammonium chloride as a by-product is dissolved in the liquid ammonia or floats on the liquid ammonia at the upper liquid level, thereby achieving physical separation from the trisilylamine.
2. A method of preparing trisilylamine according to claim 1, wherein a contact interface is formed in the reactor using a solvent and liquid ammonia, comprising:
controlling reactor temperature and pressure;
adding solvent and liquid ammonia into the reactor in sequence, so that the liquid ammonia and the solvent are distributed vertically in the reactor, and a contact interface is formed at the contact position of the liquid ammonia and the solvent.
3. The method of claim 2, wherein the reactor temperature is controlled to be-60 ℃ to 30 ℃ and the pressure is controlled to be-100 kPa to 1200kPa.
4. The method of preparing trisilylamine according to claim 1, further comprising: according to the adding amount of liquid ammonia in the reactor, the concentration of the monochlorosilane in the solvent is controlled by controlling the feeding amount of the monochlorosilane, so that the reaction degree of the monochlorosilane and the liquid ammonia on a contact interface is controlled.
5. A process for preparing trisilylamine according to claim 4,
the molar ratio of the total feeding amount of the monochlorosilane to the liquid ammonia in the reactor is 1-1.3;
and/or controlling the amount of monochlorosilane to 5-20% by weight of the solvent amount.
6. A process for preparing trisilylamine according to claim 1,
when stirring, the stirring paddle horizontally rotates at the rotating speed of 40 r/min-60 r/min;
and/or the solvent is selected from one or more of paraffin, cyclane and aromatic hydrocarbon.
7. A method for preparing trisilylamine according to claim 1, wherein the solvent is one or more of pentane, hexane, cyclohexane, heptane, octane, benzene, and toluene.
8. The method of claim 2, wherein after the reaction is complete, the method further comprises:
sending into a filter for filtering, and separating ammonium chloride from solid and liquid;
sending the liquid phase after solid-liquid separation into a primary separation tower for separation, and returning the solvent at the bottom of the separated tower to the reactor for recycling;
feeding the separated tower top material into a refining tower for rectification separation to obtain a trimethylsilyl product;
wherein, when the primary separation tower is used for separation, the pressure at the top of the tower is controlled to be 10 kPa-1000 kPa; and during rectification separation, controlling the pressure at the top of the tower to be 10 kPa-1000 kPa.
9. A method of making trisilylamine as claimed in claim 8 wherein the refining column is a dividing wall column and the trisilylamine product has a trisilylamine purity of not less than 99.5%.
10. A system for preparing trisilylamine, which is used in the method for preparing trisilylamine according to any one of claims 1 to 9, wherein the system comprises a reactor;
the reactor, comprising: the device comprises a feed inlet, a stirrer and a control assembly; wherein,
the control assembly is used for controlling the temperature and the pressure in the reactor;
the addition port, at least one, is used for adding solvent and liquid ammonia to the reactor, and the addition port is arranged as follows: after adding the solvent and the liquid ammonia, forming a contact interface at the contact liquid level between the solvent and the liquid ammonia;
the feed inlet is used for feeding monochlorosilane into the solvent in the reactor;
the stirrer is fixed in the reactor and is positioned in the solvent, and is used for stirring the solvent in a stirring mode parallel to a contact interface in the feeding process, so that monochlorosilane is dissolved in the solvent, the monochlorosilane dissolved in the solvent and liquid ammonia react at the contact interface to generate trisilylamine, and the by-product ammonium chloride is dissolved in the liquid ammonia or floats on the upper liquid level of the liquid ammonia to realize physical isolation from the trisilylamine.
11. A system for preparing trisilylamine according to claim 10,
the feed inlet is positioned at the upper part of the reactor, and the solvent and the liquid ammonia are added in sequence;
one end of the stirrer is a stirring paddle and is horizontally arranged in the solvent, and the other end of the stirrer is fixed with the reactor; the feed inlet is located in the lower part of the reactor and is lower than the contact interface.
12. The system for preparing trisilylamine according to claim 10, wherein the reactor has a jacket, and a cooling medium is introduced into the jacket for adjusting the temperature inside the reactor by heat exchange.
13. A system for preparing trisilylamine according to claim 10, wherein a flow valve is provided at the feed port for controlling the feed amount of monochlorosilane.
14. The system for preparing trisilylamine according to claim 10, further comprising: the filter, the primary separating tower and the refining tower are connected in sequence;
the filter is connected with the reactor and is used for filtering reaction products, separating solid ammonium chloride from liquid, and sending the liquid phase after solid-liquid separation into a primary separation tower;
the primary separation tower comprises an inlet, a tower bottom solvent outlet and a tower top material outlet, wherein the inlet is connected with the filter, the tower top material outlet is connected with the refining tower, and the tower bottom solvent outlet is connected with the reactor and is used for returning the separated solvent to the reactor for recycling;
the refining tower is used for receiving the materials separated by the primary separation tower, and rectifying and separating the materials to obtain a trisilylamine product;
wherein the top pressure of the primary separation tower is 10 kPa-1000 kPa; the top pressure of the refining tower is 10 kPa-1000 kPa; the rectifying tower is a dividing wall rectifying tower.
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