CN1157397C - A new process method and system for direct synthesis of organosilicon monomer - Google Patents

Abstract

The present invention relates to a new process for synthesizing an organosilicon monomer by a direct method and a system thereof, which belongs to a synthetic technique of chemical industry. The method has the characteristics that a liquid-phase ultrasonic mixer is used in the process of the mixing of reactants of silicon powder and powdery mixed catalysts; under the action of ultrasonic energy, aggregates of the powdery mixed catalysts are destroyed and uniformly dispersed over the surface of the silicon powder whose particle diameter is about 100 micrometers. A mixture of the raw material of the silicon powder and the catalysts is processed by ultrasonic solid-solid distribution; after solvents are removed, the mixture is sent into a fluidized-bed reactor and then reacts with chlorinated hydrocarbon gas, and the organosilicon monomer is prepared. The technology can largely increase the contact surface of the silicon powder and the mixed catalysts, and can accelerate a gas-solid-solid catalytic reaction of the organosilicon monomer synthesized by the direct method, and consequently, the purposes of improving the efficiency of reaction processes and reducing the consumption of the powdery mixed catalysts are reached.

Description

A new process method and system for direct synthesis of organosilicon monomer

technical field

The invention relates to a chemical synthesis technology, in particular to a process method and system for synthesizing organosilicon monomer by direct method.

Background technique

At present, the direct synthesis of organosilicon monomer technology is to pass chlorinated hydrocarbon gas into the fluidized bed to make silicon powder and powdery mixed catalyst (including the main catalyst containing cuprous oxide or cuprous chloride and the catalyst composed of other metals) Co-catalyst) fluidization to complete the catalytic chemical reaction between silicon powder and chlorinated hydrocarbon (such as methyl chloride or chlorobenzene) gas to generate organosilicon monomer (such as dichlorodimethylsilane or chlorophenylsilane).

Due to the poor contact between the powdery mixed catalyst and silicon powder during the reaction, it is difficult to fully exert the activity of the catalyst, and the fluidization is carried out. When using this process for continuous production, it is necessary to continuously add powdery mixed catalyst while adding raw silicon powder. , the catalytic reaction can be maintained normally. As described in USP5596119 (1997), the addition amount of the powdery mixed catalyst is about 5% of the silicon powder addition amount.

It is well known that the reaction of chlorinated hydrocarbons and silicon powder under the action of powdery mixed catalyst is a complex gas-solid-solid catalytic reaction. During the reaction process, the solid silicon powder first undergoes a solid-solid reaction with the solid powder mixed catalyst, and a silicon-copper alloy (η phase Cu ₃ Si) is formed on the contact surface of the silicon and the copper-containing catalyst. The silicon atoms in the silicon-copper alloy have relatively high reactivity, and can directly react with gas-phase chlorinated hydrocarbons at a certain reaction temperature to form organosilicon monomers, thereby constituting the main reaction in the reaction system. The powdery mixed catalyst that fails to contact with silicon to form a silicon-copper alloy at the reaction temperature, the copper contained in it is called free copper. It has high catalytic activity for cracking gas-phase chlorinated hydrocarbons. Cracking of chlorinated hydrocarbons yields _H2 , C, HCl, etc. as undesired products. The cracking reaction of chlorinated hydrocarbons is the main side reaction of this reaction system. In order to accelerate the main reaction and prevent the side reaction, it is necessary to optimize the reaction conditions (temperature, pressure, gas velocity, etc.), screen the silicon powder (impurity content, particle size, etc.), and screen the powdery mixed catalyst (chemical component compatibility, crystal form, particle size, etc.) ). As described in USP4504596, USP4503165, USP4450282, and USP4487950, the currently screened cuprous oxide or cuprous chloride catalysts are all very fine, with a particle size below 3 microns. There is agglomeration phenomenon in these fine powders under the surface force, and the size of the agglomerates is about 20 microns. In the existing technology, silicon powder and powdery mixed catalyst are dried and mixed in a fluidized bed with nitrogen fluidization, and the agglomerates are difficult to be dispersed under this fluidization condition. The existence of aggregates hinders the close contact between silicon and copper and the formation of silicon-copper alloys, and also leads to a large amount of free copper in the reaction system, resulting in more side reactions.

Contents of the invention

The purpose of the present invention is to provide a new process for the synthesis of organosilicon monomer by direct method. Before the fluidized mixing and drying process of silicon powder and powdery mixed catalyst, a liquid phase is introduced, and ultrasonic energy is introduced into the liquid phase. In order to realize the dispersion of powdered catalyst aggregates, it can be in close contact with silicon powder. The particle size of silicon powder is 50 to 150 microns. Under the action of ultrasonic energy, the micron-sized powdery mixed catalyst agglomerated in the liquid phase can be dispersed and partially covered on the surface of silicon powder, which expands the contact surface area of silicon and copper, thus providing a better environment for production. In the process, the addition amount of powdery mixed catalyst is greatly reduced to create conditions.

This process and its system are realized through the following technical solutions:

A synthesis process system for directly synthesizing organosilicon monomers, the system includes a silicon powder storage tank, a powdery mixed catalyst storage tank, a nitrogen fluidized bed dryer, a mixed material storage tank, a fluidized bed reactor and corresponding connections The pipeline is characterized in that a solvent recycling system is added in the process, and the system consists of a solvent storage tank, an ultrasonic mixer that enables the dispersion of the powdery mixed catalyst and silicon powder to be uniformly mixed, a solvent circulation pump, a condenser, and a solvent removal system. The desolvation tanks of the mixed material solvent are connected together through pipelines; the inlet of the ultrasonic mixer set in this process is connected with three storage tanks through pipelines, and the outlet is connected with the desolvation tank; the outlet of the desolvation tank is connected with the fluidization The bed drier is connected with pipelines, and the desolvation tank is also connected with solvent circulation pump and condenser through pipelines.

A kind of method that adopts above-mentioned synthetic process system, this process method is carried out as follows successively:

a. Silica powder, powdery mixed catalyst and solvent flow into the ultrasonic mixer from the solvent storage tank, silicon powder storage tank, and powdery mixed catalyst storage tank at room temperature for mixing, and the mixed materials through the ultrasonic mixer form a suspension, The solid content of the suspension is controlled at 20-50%;

b. The suspension after ultrasonic treatment enters the desolventization tank. In the desolventization tank, first use a suction pipe with a filter tip to filter most of the solvent through the solvent circulation pump, and then heat the mixture in the tank to the boiling point through the steam jacket. Remove the remaining solvent, and the solvent content in the solvent-removed mixture should be less than 1%;

c. Remove the mixed material from the solvent and then enter the nitrogen fluidized bed dryer for drying treatment;

d. The dried mixed material enters the mixed material storage tank, and then enters the fluidized bed reactor for reaction.

In the above synthesis process, the solvent used is methyl chloride, methylene chloride, chloroform, ethyl chloride or a mixture thereof. The ultrasonic power density of the ultrasonic mixer used ranges from 10 W/L to 500 W/L, the ultrasonic frequency ranges from 0.1 MHz to 200 MHz, and the stirring speed ranges from 10 rpm to 300 rpm.

In the above synthesis process system, the ultrasonic mixer mainly includes a motor, a shaft coupling, a solvent inlet, a powder inlet, a powder mixer main body, a stirring shaft, a discharge port, etc., and is characterized in that the axis of the ultrasonic mixer Propeller blades are installed, and ultrasonic emitters are installed on the wall of the ultrasonic mixer.

In the above-mentioned synthetic process system, the set desolventizing tank mainly includes a mixture inlet, a solvent steam outlet, a heating steam inlet, a desolventizing tank main body, a material outlet, and a condensed water outlet, and it is characterized in that the axis of the desolventizing tank is equipped with A suction pipe with a filter head, through which the solvent is sucked away by a solvent circulation pump, and a heating jacket is provided on the wall of the desolvation tank to vaporize the remaining liquid phase medium.

In the above synthesis process system, the solvent, powdery mixed catalyst and appropriate amount of silicon powder can also be added to an ultrasonic mixer, and the powdery mixed catalyst can be pre-dispersed by ultrasonic waves and mechanical stirring. Then add silicon powder, and fully mix the pre-dispersed mixed catalyst and silicon powder under the condition of ultrasonic and mechanical stirring.

The improved process according to the invention can reduce the added amount of the powdery mixed catalyst, thereby lowering the production cost, reducing the environmental pollution caused by copper, and reducing the side reactions in the reaction system.

Description of drawings

Fig. 1 is the technological process and structural representation of the present invention.

Fig. 2 is a schematic structural diagram of the ultrasonic mixer of the present invention.

Fig. 3 is a schematic diagram of the structure of the desolvation tank of the present invention.

Detailed ways

Below in conjunction with accompanying drawing, technical process of the present invention and specific implementation steps are specified:

The synthesis process system of the present invention is mainly composed of a solvent storage tank 1, a silicon powder storage tank 2, a powdery mixed catalyst storage tank 3, a product outlet 4, an ultrasonic mixer 5, a solvent circulation pump 6, a fluidized bed reactor 7, and a condenser 8. It consists of a solvent removal tank 9, a fluidized bed dryer 10, a mixture storage tank 12 and corresponding connecting pipes. The connection relationship between each equipment is as follows: solvent storage tank 1, ultrasonic mixer 5, solvent circulation pump 6, condenser 8, desolvation tank 9 for removing the solvent from the mixed material, which are connected together through pipelines to form a solvent recycling system The inlet of the ultrasonic mixer is connected to storage tanks 1, 2, and 3 through pipelines, and the outlet is connected to the desolvation tank 9; , The condenser is connected by pipes. The inlet of the fluidized bed drier 10 is connected to the outlet of the desolventizing tank 9 by a pipe, and the lower part is provided with a nitrogen inlet 13, and is connected to the upper part of the mixture storage tank 12 through a pipe. The outlet of the mixture storage tank 12 is connected to the bottom of the fluidized bed reactor 7 by a pipeline, the bottom of the fluidized bed reactor 7 is provided with a chlorinated hydrocarbon gas inlet 11, and the top is provided with a product outlet 4 (as shown in Figure 1 Show).

The specific implementation steps of this process are as follows:

Silicon powder, powdery mixed catalyst and solvent flow into ultrasonic mixer 5 respectively by solvent storage tank 1, silicon powder storage tank 2, powdery mixed catalyst storage tank 3 at room temperature and mix, the three of solvent, silicon powder and mixed catalyst The weight ratio is 3:1:0.02. The particle size of silicon powder is 50-100 microns, and the purity is 98%. The solvent is a liquid that is compatible with the chemical reaction system and has a certain cleaning effect on the silicon surface, such as chloroform, ethyl chloride, chlorobenzene, or a mixture thereof. Two kinds of powdery mixed catalysts are used: powdery mixed catalyst composed of cuprous chloride and co-catalyst, and powdery catalyst composed of cuprous oxide and co-catalyst. There is a mechanical stirring paddle in the ultrasonic mixer to make the powdery material form a suspension, and the solid content of the suspension is controlled at 20%-50%. The wall of the ultrasonic mixer is equipped with several ultrasonic emitters, and the ultrasonic power density in the mixer is controlled at 10 W/L-500 W/L. The action time of ultrasound on the suspension is controlled within 5 minutes to 10 minutes, and intermittent operation or continuous operation can be adopted.

The solution after ultrasonic treatment enters the desolventizing tank 9, in which the solvent is first sucked out by a suction pipe with a filter tip through the solvent circulation pump 6, and then the mixture in the tank is heated to the boiling point through a steam jacket to vaporize the solvent Afterwards, it is condensed by the condenser 8 to remove the remaining solvent. The solvent content in the desolventized mixture should be less than 1%. The solvent-free mixture enters the nitrogen fluidized bed dryer 10 at 130-200°C for drying treatment. The superficial gas velocity of the fluidizing gas is 0.01 m/s-0.25 m/s, and the drying time is controlled at 30 minutes-3 Hour. The dried mixed material enters the mixed material storage tank 12, and then is fed into the fluidized bed reactor 7 in batches or continuously for reaction. The temperature of the fluidized bed reactor is controlled at 280°C-300°C, and the superficial gas velocity is controlled at 0.15 m/s.

Accompanying drawing 2 is the structure diagram of ultrasonic mixer of the present invention. The ultrasonic mixer 5 is composed of a mixer tank, a spiral stirring system, an ultrasonic generating system and the like. It mainly includes motor 51, coupling 52, bearing bracket 53, solvent inlet 54, powder inlet 55, powder mixer main body 56, stirring shaft 57, propeller blade 58, ultrasonic emitting head 59, discharge port 510, etc., propeller The leaf 58 is installed on the axis of the ultrasonic mixer, and the ultrasonic emitting head 59 is arranged on the wall of the ultrasonic mixer. During the operation, the solvent, the powdery mixed catalyst and an appropriate amount of silicon powder are first added to the ultrasonic mixer, and the powdery mixed catalyst is pre-dispersed by ultrasonic waves and mechanical stirring. Then add silicon powder, and fully mix the pre-dispersed mixed catalyst and silicon powder under the condition of ultrasonic and mechanical stirring. In this way, the micro-mixed catalyst with good monodispersity can be evenly attached to the surface of the silicon powder particles. The silicon powder contact body obtained after removing the solvent and drying can be used for the synthesis reaction of organosilicon monomers. Using the ultrasonic mixer of the present invention, the solvent, silicon powder and powdery mixed catalyst can also be added together, and the dispersion of the catalyst and the uniform mixing with the silicon powder can be realized simultaneously under the action of ultrasonic and mechanical stirring. The device of the present invention can be operated in a batch mode or in a continuous mode.

Accompanying drawing 3 is the structure schematic diagram of the desolvation tank of the present invention. The solvent removal tank 9 mainly includes a mixture inlet 91, a solvent vapor outlet 92, a heating steam inlet 93, a solvent removal tank body 94, a heating jacket 97, a filter head 98, a material outlet 99, and a condensed water outlet 910. The purpose of this equipment is to remove the solvent from the mixed material treated by the ultrasonic mixer. The operation process is as follows: first, add the mixed material treated by the ultrasonic mixer into the desolventization tank, then use the solvent circulation pump to filter through the filter head to remove most of the solvent, and finally heat the silicon powder catalyst mixture in the tank through the steam jacket, Evaporation of the solvent removes the remaining solvent. The silica powder catalyst mixture after desolvation is moved into a drier for drying, and further removes moisture and solvent to achieve the required indicators for the synthesis reaction.

Example 1

The dimethyldichlorosilane (DDS) organosilicon monomer is directly synthesized by using the active cuprous chloride CuCl catalyst, and the silicon powder and the powdery mixed catalyst are stored in storage tanks 2 and 3 respectively. Silicon powder has a particle size of 50 to 150 microns and a purity of 98%. The components of the active cuprous chloride catalyst system are shown in Table 1.

Table 1. Composition of cuprous chloride catalyst system name Apparent particle size/micron Weight fraction/% Active CuCl 1-20 90 Cocatalyst 1 1-5 9 Cocatalyst 2 1-5 1

Use chloroform as the solvent and store it in a solvent storage tank at room temperature. Solvent, powdery mixed catalyst and appropriate amount of silicon powder are added to the ultrasonic mixer for pre-dispersion for 10 minutes, and then the remaining silicon powder is added and mixed for 10 minutes. The weight ratio of solvent, silicon powder and mixed catalyst is 3:1:0.02. The ultrasonic power density of the ultrasonic mixer is 50 W/L, the frequency is 10 MHz, and the stirring speed is 50 rpm. The temperature of the desolvation tank was controlled at 100°C. The chloroform solvent pumped out by the filter pump and the chloroform solvent vapor evaporated from the desolvation tank are condensed, recovered and stored in the solvent storage tank for recycling.

The solvent content in the solvent-removed mixture is controlled below 1%, and the material enters a nitrogen fluidized bed at 180°C for drying treatment. The drying time is controlled at about 1 hour, and then the mixture is transferred to the mixture storage tank, and then divided into Batch or continuous feeding into the fluidized bed reactor for synthesis reaction. The temperature of the fluidized bed reactor is controlled at 280°C to 300°C, and the superficial gas velocity is controlled at 0.15 m/s. Carry out synthetic reaction in the fluidized bed reactor with the mixed material that the present invention handles, the catalytic reaction rate of silicon powder still remains on 3% by weight (silicon)/hour, generates the selectivity of DDS and still remains on more than 80%, and powder The add-on of the mixed catalyst is reduced to 2% of the add-on of silicon powder. The added amount of the catalyst is only two-fifths of 5% of the added amount of the catalyst in the prior art.

Example 2

A copper oxide catalyst system was used, and the raw materials and synthesis reaction conditions were the same as those in Example 1 to directly synthesize dimethyldichlorosilane (DDS) organosilicon monomer. The components of the active copper oxide catalyst system are shown in Table 2.

Table 2. Composition of copper oxide catalyst system name Apparent particle size/micron Weight fraction/% Copper oxide 1-20 90 Cocatalyst 1 1-5 9 Cocatalyst 2 1-5 1

Use methyl chloride as solvent. The solvent, silicon powder and powdery mixed catalyst are fed into the ultrasonic mixer together, and the weight ratio of the three is 3:1:0.02. The mixed material stays in the ultrasonic mixer for 15 minutes, the ultrasonic power is 50 W/L, the frequency is 10 MHz, and the stirring speed is 50 rpm. Desolvation process and drying process are identical with embodiment 1. Carry out synthesis reaction in fluidized bed reactor with technique of the present invention, the catalytic reaction rate of silicon powder can still reach 3% by weight (silicon)/hour, and the selectivity of generating DDS is still more than 80%, and the powdery mixed catalyst The addition is reduced to 2% of the silicon powder addition. The added amount of the catalyst is only two-fifths of 5% of the added amount of the catalyst in the prior art.

Claims (7)

1. A synthesis process system for direct synthesis of organosilicon monomers, the system includes a silicon powder storage tank [2], a powdery mixed catalyst storage tank [3], a nitrogen fluidized bed dryer [10], a mixed material storage tank Tank [12], fluidized bed reactor [7] and corresponding connecting pipes are characterized in that a solvent recycling system is added in the process, and the system consists of solvent storage tank [1], dispersion of powdery mixed catalyst An ultrasonic mixer [5] that can be uniformly mixed with silicon powder, a solvent circulation pump [6], a condenser [8], and a desolvation tank [9] that removes the solvent of the mixed material are connected together through pipelines; the ultrasonic mixing The inlet of the device is connected to the storage tanks [1], [2], [3] through pipelines, and the outlet is connected to the desolvation tank; The circulating pump and the condenser are connected with pipelines. 2. According to the synthesis process system described in claim 1, said ultrasonic mixer [5] mainly comprises a motor [51], a shaft coupling [52], a solvent inlet [54], a powder inlet [55], a powder Material mixer main body [56], stirring shaft [57], discharge port [510], etc. It is characterized in that the axis of the ultrasonic mixer is equipped with propeller blades [58], and the wall of the ultrasonic mixer is equipped with ultrasonic emitters [ 59]. 3. according to the synthesis process system described in claim 1, described desolventizing tank [9] mainly comprises mixture inlet [91], solvent steam outlet [92], heating steam inlet [93], desolventizing tank main body [ 94], discharge port [99], condensed water outlet [910], it is characterized in that the axis of desolventization tank [9] is equipped with a suction pipe with filter head [98], and the wall of desolventization tank is equipped with to make the remaining liquid Heating jacket for phase medium vaporization [97]. 4. A method using the synthesis process system as claimed in claim 1, the method is carried out as follows: a. Silica powder, powdery mixed catalyst and solvent flow into ultrasonic mixer [5] from solvent storage tank [1], silicon powder storage tank [2], powdery mixed catalyst storage tank [3] to mix at room temperature respectively, The material mixed by an ultrasonic mixer becomes a suspension, and the solid content of the suspension is controlled at 20% to 50%; b. The suspension after ultrasonic treatment enters the solvent removal tank [9]. The mixture is heated to the boiling point to remove the remaining solvent, and the solvent content in the desolventized mixture should be less than 1%; c. The mixed material desolvated enters the nitrogen fluidized bed drier [10] for drying treatment; d. The dried mixed material enters the mixed material storage tank [12], and then enters the fluidized bed reactor [7] for reaction. 5. according to the synthetic process method described in claim 4, it is characterized in that the solvent described in the synthetic process is methyl chloride, methylene dichloride, chloroform, chloroethane or its mixture. 6. According to the synthesis process described in claim 4 or 5, it is characterized in that the ultrasonic power density range of the ultrasonic mixer is 10 watts/liter to 500 watts/liter, the ultrasonic frequency range is 0.1MHz to 200MHz, and the stirring speed The range is 10 rpm to 300 rpm. 7. according to the described synthetic process method of claim 4, it is characterized in that solvent, powdery mixed catalyst and appropriate amount of silicon powder are added to ultrasonic mixer in a step, utilize ultrasonic wave and mechanical stirring that powdery mixed catalyst is pre-dispersed, then Add the remaining silicon powder, and fully mix the pre-dispersed mixed catalyst with the remaining silicon powder under the condition of ultrasonic and mechanical stirring.

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