A feeding system for gas phase synthesis of nanomaterials

Abstract

The present invention belongs to the field of nano material production, and specifically discloses a feeding system for gas phase synthesis of nano materials. The system includes more than two groups of precursor feeding devices, each of which has the same structure, including a carrier gas unit, a precursor unit and a mixing unit, wherein: the precursor unit extends into the mixing unit to provide a liquid precursor to the mixing unit; the end of the carrier gas unit extends into the mixing unit through a bubbling nozzle to provide a carrier gas to the mixing unit; the mixing unit generates precursor vapor by heating the liquid precursor, and sends it into the precursor reactor under the carrier gas. The present invention adjusts the concentration and flow of each precursor by controlling the carrier gas flow rate and heating temperature of each group of feeding devices to meet the requirements of gas phase synthesis of nano materials preparation, and realizes the precise adjustment of the precursor raw material supply concentration, flow rate and mixing ratio.

Description

Technical Field

[0001] The invention belongs to the field of nano material production, and more specifically, relates to a feeding system for gas phase synthesis of nano materials. Background Art

[0002] Gas phase synthesis technology is a large-scale commercial nanoparticle production technology, including the flame method to prepare gas phase silica (SiO2), the chlorination method to prepare titanium dioxide (TiO2), etc. Its advantages are that it can be produced automatically and continuously, and there is no discharge of wastewater and waste residue. The basic process of gas phase synthesis is that the volatile precursor raw materials (such as SiCl4, TiCl4) are heated and gasified, injected into a high-temperature reactor for rapid oxidation, hydrolysis and other reactions to form initial monomers, and then undergo nucleation, collision, condensation, sintering and other particle dynamic processes and crystal phase transformation to generate the final particle product.

[0003] Gas phase synthesis can synthesize uniform ultrafine particles with particle sizes ranging from a few nanometers to hundreds of nanometers in one step. One of the very important process parameters is the concentration and flow rate of the precursor vapor, which determines the particle size and yield of the particle product. In addition, for composite nanomaterials of two or more components, it is also necessary to control the mixing ratio of each precursor vapor. Therefore, how to achieve precise adjustment of the precursor raw material supply concentration, flow rate and mixing ratio is a technical problem that needs to be urgently solved in the existing technology. Summary of the invention

[0004] In response to the above defects or improvement needs of the prior art, the present invention provides a feeding system for gas-phase synthesis of nanomaterials, wherein the system includes more than two groups of precursor feeding devices, and the concentration and flow rate of each precursor are adjusted by controlling the carrier gas flow rate and heating temperature of each group of feeding devices to meet the requirements of gas-phase synthesis of nanomaterials preparation, thereby achieving precise adjustment of the precursor raw material supply concentration, flow rate and mixing ratio.

[0005] To achieve the above-mentioned purpose, the present invention proposes a feeding system for gas-phase synthesis of nanomaterials, which includes more than two groups of precursor feeding devices, each of which has the same structure and includes a carrier gas unit, a precursor unit and a mixing unit, wherein: the precursor unit extends into the mixing unit to provide a liquid precursor to the mixing unit; the end of the carrier gas unit extends into the mixing unit through a bubbling nozzle to provide a carrier gas to the mixing unit; the mixing unit generates precursor vapor by heating the liquid precursor, and delivers the precursor vapor to a precursor reactor under the carrier gas; during operation, the concentration and flow rate of each precursor are adjusted by controlling the carrier gas flow rate and heating temperature of each group of precursor feeding devices to meet the requirements for the preparation of gas-phase synthesis of nanomaterials.

[0006] As a further preference, the carrier gas unit includes a carrier gas source, a gas valve and a gas flow controller connected in sequence, wherein the carrier gas source is used to provide carrier gas, the gas valve is used to control the on and off of the carrier gas, and the gas flow controller is used to measure and control the flow of the carrier gas.

[0007] As a further preference, the carrier gas unit further comprises a particle filter, and the particle filter is arranged in front of the bubbling nozzle for removing and purifying particles from the carrier gas.

[0008] As further preferred, the carrier gas unit further includes a dryer, which is arranged in front of the bubbling nozzle and is used for dehydrating and drying the carrier gas.

[0009] As further preferred, the carrier gas is compressed air, nitrogen or argon.

[0010] As a further preference, the precursor unit comprises a precursor storage tank and a precursor dosing pump, wherein the precursor storage tank is used to store and supply the liquid precursor; one end of the precursor dosing pump is connected to the precursor storage tank, and the other end thereof extends into the mixing unit, for conveying the liquid precursor to the mixing unit.

[0011] As further preferred, the mixing unit comprises a precursor heater and a heating pipe, the precursor heater is used to heat the liquid precursor to generate the precursor vapor, and the heating pipe is used to heat the precursor vapor carried by the carrier gas to an undersaturated state.

[0012] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0013] 1. The present invention provides a feeding system for gas phase synthesis of nanomaterials, the system comprising two or more groups of precursor feeding devices, each group of feeding devices being provided with a precursor unit, a carrier gas unit and a mixing unit, and the concentration and flow rate of each precursor being adjusted by controlling the carrier gas flow rate and heating temperature of each group of feeding devices to meet the requirements of gas phase synthesis of nanomaterial preparation, and to achieve accurate adjustment of the supply concentration, flow rate and mixing ratio of the precursor raw materials;

[0014] 2. In particular, the present invention can further improve the working efficiency and working accuracy of each group of precursor feeding devices by optimizing the specific structures of the precursor unit, the carrier gas unit and the mixing unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of a precursor feeding device constructed according to a preferred embodiment of the present invention;

[0016] Figure 2 It is a schematic structural diagram of a feeding system for gas phase synthesis of nanomaterials constructed according to a preferred embodiment of the present invention;

[0017] Figure 3 is the relationship between the saturated vapor pressure and temperature of the precursor titanium tetrachloride in the preferred embodiment of the present invention;

[0018] Figure 4 is the relationship between the saturated vapor pressure and temperature of the precursor silicon tetrachloride in the preferred embodiment of the present invention;

[0019] Figure 5 This is the relationship between the saturated vapor pressure and temperature of the precursor dimethylaluminum chloride in the preferred embodiment of the present invention.

[0020] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0021] 1-carrier gas source, 2-gas valve, 3-gas flow controller, 4-particle filter, 5-dryer, 6-precursor storage tank, 7-precursor metering pump, 8-precursor heater, 9-bubble nozzle, 10-heating pipeline, 11-precursor reactor. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] like Figure 1 , 2 As shown, an embodiment of the present invention provides a feeding system for gas phase synthesis of nanomaterials, the system includes two or more groups of precursor feeding devices, each precursor feeding device has the same structure, including a carrier gas unit, a precursor unit and a mixing unit, wherein:

[0024] The precursor unit extends into the mixing unit, and is used to provide a liquid precursor to the mixing unit. The precursor unit includes a precursor storage tank 6 and a precursor dosing pump 7. The precursor storage tank 6 is used to store and supply the liquid precursor. One end of the precursor dosing pump 7 is connected to the precursor storage tank 6, and the other end thereof extends into the mixing unit, and is used to transport the liquid precursor to the mixing unit.

[0025] The end of the carrier gas unit extends into the mixing unit through a bubbling nozzle, which is used to provide carrier gas to the mixing unit. The carrier gas unit includes a carrier gas source 1, a gas valve 2 and a gas flow controller 3 connected in sequence, wherein the carrier gas source 1 is used to provide carrier gas, the gas valve 2 is used to control the on and off of the carrier gas, and the gas flow controller 3 is used to measure and control the flow of the carrier gas; the bubbling nozzle is kept below the liquid level and does not touch the bottom, and the carrier gas is introduced into the liquid precursor and evenly dispersed to form a stable and fine bubble flow, so that the precursor vapor carried by the carrier gas reaches saturation;

[0026] The mixing unit generates precursor vapor by heating the liquid precursor, and delivers the precursor vapor to the precursor reactor under the carrier gas. The mixing unit includes a precursor heater 8 and a heating pipe 10. The precursor heater 8 has temperature and pressure control functions and is used to heat the liquid precursor to a fixed temperature (below the boiling point of the precursor) to generate precursor vapor. The heating pipe 10 has a temperature control function and is used to heat the precursor vapor carried by the carrier gas to an undersaturated (superheated) state, place the precursor vapor condensed, and deliver it to a reaction device for synthesizing meteorological nanomaterials (including a flame reactor, a hot wall heater, etc.);

[0027] During operation, the groups of precursor feeding devices are connected in parallel, and each group of precursor feeding devices supplies a precursor vapor. The concentration and flow rate of each precursor are adjusted by controlling the carrier gas flow rate and heating temperature of each group of precursor feeding devices to meet the requirements of gas phase synthesis of nanomaterials, thereby effectively adjusting the particle size, particle yield or component ratio of the nanomaterials.

[0028] Furthermore, the carrier gas unit further includes a particle filter 4 and a dryer 5, which are arranged between the bubbling nozzle 9 and the gas flow controller 3, and the order of the particle filter 4 and the dryer can be interchanged, the particle filter 4 is used to remove particles from the carrier gas, and the dryer 5 is used to dehydrate and dry the carrier gas. The carrier gas is compressed air, nitrogen, argon or other gases that do not react with the precursor.

[0029] The following is a detailed description of the use of the feeding system for gas phase synthesis of nanomaterials provided by the present invention.

[0030] First, perform routine calibration and inspection procedures, including calibration of mass flow controllers, inspection of gas pressure in cylinders, inspection of pipeline air tightness and patency, inspection of electrical control components, and inspection of carrier gas dryers, etc. Operation can only be started when all conditions are confirmed to be normal.

[0031] 80-100 ml of titanium tetrachloride liquid (melting point 249.95K, boiling point 409.05K) is measured and poured into a raw material container round bottom flask with a capacity of 250 ml. A glass bubbling nozzle with a resin plug is inserted into the flask so that the raw material liquid level is above the bubbling nozzle 9 and the bubbling nozzle 9 cannot touch the bottom. The other outlet is connected to the heating pipe 10, the plug is sealed, and the flask is placed in a constant temperature heating device to form a precursor heater 8, which is fixed with an iron stand. To replenish the titanium tetrachloride liquid, a precursor storage tank 6 and a precursor dosing pump 7 can be set to transport the titanium tetrachloride liquid to the precursor heater 8.

[0032] Similarly, the loading of silicon tetrachloride liquid (melting point 204.85K, boiling point 330.15K) and dimethylaluminum chloride liquid (melting point 252K, boiling point 399K) was completed in sequence.

[0033] Open the cylinder gas valve 2 and the gas flow controller 3 in sequence, and adjust the gas flow controller 3 at a flow rate of 0.20-0.80 NL / min to allow the carrier gas nitrogen to purge the entire device. At this time, use an alkaline / organic solution to absorb the raw material gas brought out by the carrier gas.

[0034] The temperature of the heating device is adjusted to control the vaporization heating temperature of the liquid precursor, and heating is started. At the same time, the temperature of the heating pipe 10 is set to be slightly higher than the vaporization heating temperature and heating is started.

[0035] As described above, the vaporization heating temperature of titanium tetrachloride can be controlled to be 338K, the temperature of the heat pipe to be 343K, the pressure in the round-bottom flask to be maintained at 1atm, and the flow rate of the carrier gas nitrogen to be set to 0.60NL / min. According to the relationship between its saturated vapor pressure P (Pa) and temperature T (K) (Antoine equation):

[0036]

[0037] In order to intuitively show its changing law, we draw Figure 3 According to the carrier gas flow rate, heating vaporization temperature and ideal gas state equation, the current vapor flow rate of titanium tetrachloride can be calculated to be 3.0×10 -3 mol / min.

[0038] Accordingly, the vapor flow of other precursors can be controlled according to the heating and vaporization temperature, carrier gas flow rate, and the relationship between saturated vapor pressure and temperature of other raw materials, thereby achieving accurate composite feeding. Figure 4 , 5 As shown, the relationship between the saturated vapor pressure and temperature of silicon tetrachloride and dimethylaluminum chloride in the current embodiment is:

[0039]

[0040]

[0041] The gasification heating temperature of silicon tetrachloride is controlled to be 293K, the temperature of the heat pipe is 298K, and the carrier gas flow rate can be controlled to be 0.20NL / min. At this time, according to the relationship between its saturated vapor pressure and temperature, it can be calculated that the current vapor flow rate of silicon tetrachloride is 3.0×10 -3 mol / min.

[0042] The vaporization heating temperature of dimethylaluminum chloride is controlled to be 343K, the temperature of the heat pipe is 348K, and the carrier gas flow rate can be controlled to be 0.50NL / min. At this time, according to the relationship between its saturated vapor pressure and temperature, it can be calculated that the current vapor flow rate of dimethylaluminum chloride is 4.0×10 -3 mol / min.

[0043] According to the above conditions, the device can simultaneously provide 3.0×10 -3 mol / min、3.0×10 -3 mol / min、4.0×10 -3 mol / min of titanium tetrachloride, silicon tetrachloride and dimethylaluminum chloride vapor enters the flame synthesis reactor to produce composite nanoparticles with a specific content ratio.

[0044] The present embodiments are illustrative in all respects and are not restrictive. The above embodiments may be omitted, replaced, and modified in many ways without departing from the claims and the gist thereof.

[0045] It should be noted that, in the above-mentioned embodiment, the volatile liquid precursor raw material is not limited to titanium tetrachloride, silicon tetrachloride, and dimethylaluminum chloride, but may also be other precursors, such as triethylaluminum trichloride.

[0046] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for gas phase synthesis of nanoparticle materials, characterized in that: The feed system used includes three groups of precursor feed devices, each of which has the same structure and includes a carrier gas unit, a precursor unit and a mixing unit, wherein: the precursor unit extends into the mixing unit to provide a liquid precursor to the mixing unit; the end of the carrier gas unit extends into the mixing unit through a bubbling nozzle (9) to provide a carrier gas to the mixing unit; the mixing unit generates precursor vapor by heating the liquid precursor and delivers the precursor vapor to a precursor reactor (11) under the carrier gas; during operation, the concentration and flow rate of each precursor are adjusted by controlling the carrier gas flow rate and heating temperature of each group of precursor feed devices to meet the requirements for the preparation of gas-phase synthesis nanoparticle materials; The precursor reactor (11) is a flame synthesis reactor; the carrier gas unit comprises a carrier gas source (1), a gas valve (2) and a gas flow controller (3) connected in sequence, wherein the carrier gas source (1) is used to provide carrier gas, the gas valve (2) is used to control the on and off of the carrier gas, and the gas flow controller (3) is used to measure and control the flow of the carrier gas; The mixing unit comprises a precursor heater (8) and a heating pipe (10), wherein the precursor heater (8) is used to heat the liquid precursor to generate the precursor vapor, and the heating pipe (10) is used to heat the precursor vapor carried by the carrier gas to an undersaturated state; The method for using the feeding system includes: 80-100 ml of titanium tetrachloride liquid is measured and poured into a raw material container round bottom flask with a capacity of 250 ml. A glass bubbling nozzle with a resin rubber stopper is inserted into the flask so that the raw material liquid level is above the bubbling nozzle (9) and the bubbling nozzle (9) cannot touch the bottom. The other outlet is connected to the heating pipe (10), the rubber stopper is sealed, and the flask is placed in a constant temperature heating device to form a precursor heater (8), fixed with an iron stand, and then the silicon tetrachloride liquid and dimethylaluminum chloride liquid are loaded in sequence; Open the cylinder gas valve (2) and the gas flow controller (3) in sequence, and adjust the gas flow controller (3) at a flow rate of 0.20 to 0.80 NL / min to allow the carrier gas nitrogen to purge the entire device; The vaporization heating temperature of titanium tetrachloride was controlled to be 338K by the precursor heater (8), the temperature of the heating pipe (10) was 343K, the pressure in the round-bottom flask was maintained at 1atm, and the flow rate of carrier gas nitrogen was set to 0.60NL / min, so that the current vapor flow rate of titanium tetrachloride was 3.0×10 -3 mol / min; The gasification heating temperature of silicon tetrachloride is controlled to be 293K, the temperature of the heat pipe is 298K, and the carrier gas flow rate can be controlled to be 0.20NL / min, making the current vapor flow rate of silicon tetrachloride 3.0×10 -3 mol / min; The vaporization heating temperature of dimethylaluminum chloride is controlled to be 343K, the temperature of the heat pipe is 348K, and the carrier gas flow rate can be controlled to be 0.50NL / min, so that the current vapor flow rate of dimethylaluminum chloride is 4.0×10 -3 mol / min; Finally, they enter into flame synthesis reactor synchronously to generate composite nanoparticles.

2. The method for gas phase synthesis of nanoparticle material according to claim 1, characterized in that: The carrier gas unit further comprises a particle filter (4), which is arranged in front of the bubbling nozzle (9) and is used for removing particles from the carrier gas and purifying the carrier gas.

3. The method for gas phase synthesis of nanoparticle material according to claim 1, characterized in that: The carrier gas unit further comprises a dryer (5), which is arranged in front of the bubbling nozzle and is used for dehydrating and drying the carrier gas.

4. The method for gas phase synthesis of nanoparticle material according to claim 1, characterized in that: The carrier gas is compressed air, nitrogen or argon.

5. The method for gas phase synthesis of nanoparticle material according to claim 1, characterized in that: The precursor unit comprises a precursor storage tank (6) and a precursor dosing pump (7), wherein the precursor storage tank (6) is used to store and supply the liquid precursor; one end of the precursor dosing pump (7) is connected to the precursor storage tank (6), and the other end thereof extends into the mixing unit, so as to transport the liquid precursor to the mixing unit.

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