CN115365511B - Gas-phase reduction and collection device and method for narrow-distribution superfine molybdenum powder - Google Patents
Gas-phase reduction and collection device and method for narrow-distribution superfine molybdenum powder Download PDFInfo
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Abstract
A gas-phase reduction and collection device and a method for narrow-distribution superfine molybdenum powder. The invention utilizes MoO 3 The sublimation efficiency is highest at about 900 ℃, and MoO is realized by heating 3 Sublimation. MoO control by temperature and pressure regulation of sublimation process 3 Sublimation gas amount and molecular weight, and simultaneously blowing off in time to ensure MoO 3 Stabilizing sublimation. By the method of arranging the microchannel reactor, the instantaneous uniform mixing and the complete consistent reaction conditions of the gas-phase molybdenum source and the hydrogen in time and space are realized, the molybdenum trioxide is completely reduced in a very short time, and the distribution interval of the superfine molybdenum powder with narrow granularity is ensured. And when the product is introduced into alcohol to generate bubbles, the bubbles are crushed by a stirring device with a zigzag impeller, so that the size of the bubbles is drastically reduced, the contact area between the bubbles containing molybdenum powder particles and the alcohol is enlarged, the rapid cooling and collection of the superfine molybdenum powder are realized, and the aggregation phenomenon of the superfine molybdenum powder is reduced.
Description
Technical Field
The invention relates to a processing device and a processing method of molybdenum powder, in particular to a device and a method for gas-phase reduction and collection of narrow-distribution superfine molybdenum powder.
Background
The refractory metal molybdenum has a melting point as high as 2610 ℃, has excellent heat conduction, electric conduction and corrosion resistance, and has low thermal expansion coefficient, higher hardness and good high-temperature strength, thus having wide application in the fields of electronic industry, aerospace industry, energy industry and the like. The superfine molybdenum powder with the particle size smaller than 1.5 μm has more excellent mechanical, electrical, magnetic, thermal, optical and chemical (including catalyst) properties. Ultrafine powders are commonly used in the production of powder metallurgy and cermet compacts, alloys, specialty ceramics and electrical components. They are good fillers, abrasives, pigments, catalysts, and can be used for corrosion-, wear-and heat-resistant coatings. Adding 3-5% of superfine molybdenum powder into molybdenum powder with common granularity for compression molding and sintering, so that the sintering temperature is greatly reduced, and molybdenum alloy products with high density can be obtained. The granularity of the molybdenum powder has great influence on the chemical property of the molybdenum powder, and researches show that the molybdenum powder with different granularity has different sintering activities and catalytic activities. Thus, obtaining a narrow distribution profile is one of the most important indicators of ultra-fine molybdenum powders.
The existing preparation of superfine molybdenum powder is mainly divided into a thermal decomposition method and a reduction method. The thermal decomposition method is to react chlorine with molybdenite to prepare MoCl 6 Then high-temperature heating to decompose MoCl 6 Preparing superfine molybdenum powder; the reduction method is further divided into C reduction method and H 2 Reduction. The carbon reduction method is to reduce C and MoO 3 Performing high-energy ball milling, and obtaining MoO through low temperature Duan Xian 2 Continuously reducing in a high-temperature section to obtain superfine molybdenum powder; h 2 The reduction method is to use H 2 As a reducing agent, industrial molybdenum oxide, molybdenum carbonyl or molybdenum chloride is reduced in a closed and high-temperature environment to prepare superfine molybdenum powder. In addition, the superfine molybdenum powder can be obtained by reducing superfine precursors such as sublimated molybdenum trioxide, superfine ammonium octamolybdate and other raw materials.
Currently, such techniques have some drawbacks and limitations, in particular:
1) The thermal decomposition method takes molybdenum pentachloride as a raw material, and prepares superfine molybdenum powder through high-temperature heating decomposition. However, chlorine is used in the preparation and purification processes of molybdenum pentachloride, and the pollution of the chlorine to the atmosphere and the harm to human, livestock and plants should be paid attention to, so that the molybdenum powder prepared by the method is not suitable for industrial mass production. The preparation process of the molybdenum chloride thermal decomposition method is simple, and the molybdenum powder with higher purity can be produced, and the granularity of the molybdenum powder is smaller; however, the molybdenum chloride thermal decomposition method has higher requirements on the adopted raw materials, and the problems of exhaust and recovery treatment of the treated waste gas are also required to be paid attention to during the use.
The specific experimental procedure can be summarized as: the molybdenite concentrate is used as raw material, and is subjected to chlorine treatment by chlorine gas at 270 DEG CFormation of MoCl 5 The reaction formula is as follows:
2MoS 2 +5Cl 2 ＝2MoCl 5 +2S 2 (1)
then, pure molybdenum powder can be obtained through thermal decomposition, and the reaction formula is as follows:
2MoCl 5 ＝2Mo+5Cl 2 (2)
2) C reduction of MoO 3 In the experimental process, moO is firstly adopted 3 Mechanical mixing with C, uniformity of mixing affects reactant contact area, nucleation rate of the product, diffusion rate of the reactant through the product phase and thus directly affects reaction rate and progress; further, it is very difficult to control the amount of carbon added, and an excessive amount of carbon is likely to introduce impurities, while an insufficient amount of carbon is likely to cause insufficient reduction. In addition, carbon reduction produces CO 2 The gas emissions, which are not compatible with the national "two carbon" objectives, will be limited in the future.
Saghafi et al by combining MoO 3 Mixing with C in high-energy ball mill, and making MoO at low temperature Duan Xian 2 And then continuously reducing in a high temperature section to prepare the superfine molybdenum powder with the average grain size of 45 nm. The main reactions are shown in formulas (3) and (4).
600℃ 2MoO 3 +C＝2MoO+CO 2 (3)
1050℃ MoO 2 +2C＝Mo+2CO (4)
However, it is very difficult to precisely control the addition amount of carbon in the preparation of molybdenum powder by carbothermic reduction, molybdenum carbide is easily generated from the product when the carbon is added in excess, and molybdenum oxide cannot be completely reduced to molybdenum powder when the carbon is added in insufficient amount.
3) Molybdenum carbonyl and molybdenum fluoride required by the chemical vapor reduction method are ideal methods for preparing the narrow-distribution superfine molybdenum powder. However, since the raw materials are very expensive and molybdenum fluoride generates HF during use, its strong corrosiveness and toxicity are extremely stringent for equipment and operators. Similarly, the preparation of molybdenum carbonyl needs to be carried out in a CO environment, has strict requirements on the reaction environment, and is difficult to realize industrial production.
The gas phase reduction technology is studied to prepare tungsten-molybdenum metal powder in the early 60 s of the world, and a great deal of technical development and application are performed in Ultramet in the United states. However, the existing molybdenum gas phase reduction technology mainly uses molybdenum chloride, molybdenum fluoride and molybdenum carbonyl as metal gas phases, the gas phases are very expensive, and the molybdenum chloride reacts with hydrogen to generate HCl gas, and the molybdenum fluoride is heated and volatilized into gas at low temperature and then reacts with H in the use process 2 Mixing to perform gas phase reaction to produce Mo and HF gas. At present, recycling of HF gas has been successfully solved. However, both hydrofluoric acid and HF itself are highly corrosive and toxic, placing stringent demands on equipment and personnel handling. Likewise, molybdenum carbonyl needs to be carried out in a CO environment in the preparation process, and the nickel carbonyl has been studied successfully and involved in iron carbonyl and molybdenum carbonyl, but the strict preparation environment severely limits the popularization of the nickel carbonyl in industry.
4)H 2 Reduction of MoO 3 The method is a traditional molybdenum powder preparation method, and comprises a first-stage reduction method, a second-stage reduction method and a third-stage reduction method, wherein the reaction process of the first-stage reduction is difficult to control, and the obtained molybdenum powder has coarse granularity and poor quality; the process with the greatest influence on the quality of the molybdenum powder in the two-stage reduction is the two-stage reduction of the molybdenum powder, namely MoO 2 The process of reducing the molybdenum powder is that the crude molybdenum powder obtained by the two-stage reduction is sieved and evenly mixed to obtain the finished molybdenum powder with the granularity of 3-4 mu m; the three-stage reduction is mainly used for preparing high-purity molybdenum powder with low oxygen content and large-granularity molybdenum powder. If it is desired to prepare ultra-fine molybdenum powder by hydrogen reduction, ultra-fine precursors such as sublimated molybdenum trioxide, fine fraction ammonium octamolybdate, molybdic acid, etc. must be used.
The hydrogen reduction of molybdenum oxide mainly comprises 3 traditional process flows: moO (MoO) 3 One-stage reduction, moO 3 Two-stage reduction and MoO 3 And (3) three-stage reduction. MoO (MoO) 3 The one-stage reduction process is simple, intermediate steps such as screening, batch combination and the like are not needed in the reduction process, and MoO can be realized 3 One-step reduction to molybdenum powder. However, the reaction process of one-stage reduction is difficult to control, and the obtained molybdenum powder has low purity and coarse granularityAnd is of poor quality. The two-stage reduction process is to firstly reduce MoO 3 Reduction to MoO 2 And then feeding the mixed materials into a furnace again, heating to a higher temperature zone, and reducing the mixed materials into molybdenum powder. The molybdenum powder prepared by the two-stage reduction process has good quality and finer granularity (3-4 mu m). MoO (MoO) 3 Two-stage reduction is the most commonly used process in industry, for example, jin Dui city molybdenum company, inc. invented a method for preparing molybdenum powder by two-stage reduction using molybdenum trioxide as a raw material: putting the ball-milled molybdenum trioxide powder in a hydrogen atmosphere, and in the first stage, performing MoO 3 Reduction to MoO 2 The second stage is MoO 2 And continuously reducing into crude Mo powder, and finally sieving the crude Mo powder, and uniformly mixing in a mixer to obtain the finished molybdenum powder. In the process of preparing molybdenum powder by hydrogen reduction, the process with the greatest influence on the quality of the molybdenum powder is two-stage reduction of the molybdenum powder, namely MoO 2 And (3) reducing into molybdenum powder. MoO (MoO) 3 The three-stage reduction method is to perform high-temperature oxygen reduction again under the condition that the oxygen content of the molybdenum powder obtained after two times of reduction is still high. The process is mainly used for preparing molybdenum powder with special purpose, such as high-purity molybdenum powder with extremely low oxygen content and molybdenum powder with large granularity of more than 10 mu m.
The nano molybdenum powder is successfully prepared by mixing and reducing gas-phase sublimates generated by sublimating molybdenum oxide and hydrogen gas by using two gas phases, such as Beijing university of science and technology Zhang Guohua (patent number CN 110227826A). However, the superfine molybdenum powder has a simple structure due to the simple structure of the gas phase reaction kettle, and the difference between a micro-area thermal field and atmosphere is large, so that uniform particle size distribution is difficult to ensure.
Particularly, the superfine molybdenum powder reduction technology has larger change due to reaction micro-area condition factors (temperature, gas concentration and the like) in the reduction process. For example, in conventional reactors, the microscopic mixing rate of the reactants is less than the chemical reaction rate, and thus the reaction process is affected by mass transfer, resulting in inconsistent chemical reaction rates throughout the reactor, with localized supersaturation differences. Meanwhile, the thickness of the gas flow boundary layer in the traditional reactor is low, and the temperature conduction efficiency is low, so that the local temperature is inconsistent with the whole temperature. The nano particles prepared under the conditions have large particle size and wide distribution, and the agglomeration probability among particles is large, so that the quality of the product is greatly reduced, the distribution of the granularity of the produced superfine molybdenum powder is wider, and the quality of the product is greatly reduced. This has a very severe effect on the surface activity of the ultra-fine molybdenum powder, directly resulting in a significant difference in its subsequent use properties.
Disclosure of Invention
The invention aims to provide a device and a method for gas-phase reduction and collection of superfine molybdenum powder with narrow particle size distribution, high efficiency, low cost and greenization preparation of the superfine molybdenum powder, which can realize the integrated formation from industrial molybdenum trioxide to superfine molybdenum powder with uniform particle size, greatly reduce equipment investment and operation cost, reduce the energy consumption and pollution emission of the preparation of the superfine molybdenum powder, and realize the narrow-distribution superfine molybdenum powder gas-phase reduction and collection of the superfine molybdenum powder.
In order to achieve the aim, the device comprises a molybdenum source stable sublimation zone, a rapid reduction zone and a cooling and collecting zone which are communicated in sequence;
the molybdenum source stable sublimation zone comprises a molybdenum trioxide evaporation tank, wherein an inlet of the molybdenum trioxide evaporation tank is connected with the argon pressure maintaining tank, and an outlet of the molybdenum trioxide evaporation tank is connected with the polar speed reduction zone;
the rapid reduction zone is a microchannel reactor with an inlet end connected with an outlet of the molybdenum trioxide evaporation tank and an outlet end connected with a cooling and collecting zone, and the microchannel reactor consists of a tubular hydrogen distribution bin, a central support rod and a microchannel. The tubular hydrogen gas distribution bin is of a concentric multilayer structure, a plurality of micro-channels are distributed among each tubular hydrogen gas distribution bin along concentric circles, a plurality of small holes are uniformly distributed on a tangent line of the inner wall of each tubular hydrogen gas distribution bin and the micro-channels, a plurality of small holes are uniformly distributed on a tangent line of each micro-channel and the inner side of the tubular hydrogen gas distribution bin, the tubular hydrogen gas distribution bin corresponds to the small holes on the micro-channels, and hydrogen enters the micro-channels from the tubular hydrogen gas distribution bin through the small holes under the action of pressure. The method comprises the steps of carrying out a first treatment on the surface of the
The cooling and collecting area comprises a cooling and collecting device and absolute ethyl alcohol arranged in the cooling and collecting device, and the outlet of the micro-channel reactor extends into the absolute ethyl alcohol.
And an inlet valve and an outlet valve are respectively arranged on the inlet pipeline and the outlet pipeline of the molybdenum trioxide evaporation tank.
And a pressure detection meter is arranged on the molybdenum trioxide evaporation tank.
And a blow-off device is arranged on one side of the molybdenum trioxide evaporation tank, which is opposite to the outlet.
The inlet of the microchannel reactor is a conical airflow buffer with an inverted conical structure.
The center of the microchannel reactor is provided with a support rod, the microchannels of the innermost layer are arranged along the circumference of the support rod, and the diameter of each microchannel is 10-1000 mu m.
And a stirring device is arranged in the cooling and collecting device.
The hydrogen valve is arranged on a road where the hydrogen and water vapor separation and buffer tank are communicated with the tubular hydrogen distribution bin.
The cooling and collecting device is also connected with a recovery area, and the recovery area comprises a gas, water and ethanol separator and a hydrogen-argon separator which are respectively connected with the argon pressure maintaining tank, the hydrogen and water vapor separation and buffer tank.
The gas phase reduction and collection method of the narrow-distribution superfine molybdenum powder comprises the following steps:
1) Stable sublimation of gas-phase molybdenum source
High purity MoO 3 Placing the furnace temperature in a molybdenum trioxide evaporation tank, opening an argon pressure maintaining tank to replace air in the molybdenum trioxide evaporation tank in a vacuum exhaust and gas replacement mode, raising the furnace temperature to 900 ℃ under the protection of argon, and opening an outlet valve and a blowing-off device to sublimate MoO when the positive pressure in the furnace is more than or equal to 50pa 3 The gas flow drives the micro-channel reactor;
2) Gas phase mixing and rapid reduction
Simultaneously, hydrogen enters the micro-channel from the tubular hydrogen distribution bin through the micro-holes and enters the gas-phase MoO with the axis of the micro-channel 3 Forming vertical cross air flow, realizing the reaction condition that the gas-phase molybdenum source and hydrogen are uniformly mixed instantaneously and completely in the time and space, and generating superfine molybdenum powder with narrow particle size distribution through uniform mixing and rapid reduction;
3) Cooling and collecting superfine molybdenum powder
Ultrafine molybdenum powder with narrow particle size distribution generated by reduction flows out from the other side of the micro-channel reactor under the action of gas pressure, is led into absolute ethyl alcohol of a cooling and collecting device through a pipeline at the outlet of the micro-channel reactor, breaks up generated bubbles through a stirring device, increases the contact area between the bubbles and a collecting liquid, namely absolute ethyl alcohol, so that molybdenum powder particles are cooled and collected, and molybdenum powder particles in the bubbles are remained in the collecting liquid at the moment; vapor and excessive hydrogen generated by gas phase reduction are discharged out of the cooling and collecting device along with bubbles, and a collecting liquid containing molybdenum powder particles is dried in an argon environment to obtain superfine molybdenum powder;
4) Recycling and utilization
The unreacted water vapor, hydrogen and argon are returned to the corresponding hydrogen and water vapor separation and buffer tank and argon pressure maintaining tank for recycling through the gas, water and ethanol separators and the hydrogen-argon separators.
The invention utilizes MoO 3 The sublimation efficiency is highest at about 900 ℃, and MoO is realized by heating 3 Sublimation. And controlling MoO by temperature and pressure of sublimation process 3 Sublimation amount and molecular weight. Controlling blow-off sublimated MoO by controlling fan speed 3 Steam ensures the stable evaporation of molybdenum trioxide; the homogeneous mixing of the reactants in the same time space is the key to achieving product consistency. By the method for arranging the microchannel reactor, the invention realizes the instant uniform mixing and completely consistent reaction conditions of the gas-phase molybdenum source and the hydrogen in time and space, realizes the complete reduction of molybdenum trioxide in a very short time and ensures the distribution interval of the superfine molybdenum powder with narrow granularity. The traditional cooling process for preparing superfine molybdenum powder by gas phase reduction is furnace cooling, and the particle size is very small, so that agglomeration phenomenon easily occurs to cause uneven particle size. According to the invention, absolute alcohol is used as cooling and collecting liquid, when the product is introduced into alcohol to generate bubbles, the bubbles are crushed by the stirring device with the zigzag impeller, so that the size of the bubbles is drastically reduced, the contact area between the bubbles containing molybdenum powder particles and the alcohol is enlarged, the rapid cooling and collecting of superfine molybdenum powder is realized, and the aggregation phenomenon of superfine molybdenum powder is reduced.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
FIG. 2 is a schematic diagram of the structure of a microchannel reactor 12 of the present invention.
Fig. 3 is a side view of fig. 2 of the present invention.
Wherein: 1. the device comprises a molybdenum source stable sublimation zone, 2, an extremely rapid reduction zone, 3, a cooling and collecting zone, 4, a recovery zone, 5, an argon pressure maintaining tank, 6, an inlet valve, 7, a blow-off device, 8, a pressure detection meter, 9, a molybdenum trioxide evaporation tank, 10, molybdenum trioxide, 11, an outlet valve, 12, a microchannel reactor, 13, a cooling and collecting device, 14, a collecting object, 15, a stirring device, 16, a hydrogen valve, 17, a hydrogen and water vapor steam-water separation and buffer tank, 121, molybdenum trioxide steam, 122, a conical airflow buffer, 123, a tubular hydrogen gas distribution bin, 124, a support rod and 125 microchannels.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
Referring to fig. 1, the apparatus of the present invention comprises a molybdenum source stabilization sublimation zone 1, a very rapid reduction zone 2 and a cooling and collecting zone 3, which are sequentially connected;
the molybdenum source stable sublimation zone 1 comprises a molybdenum trioxide evaporation tank 9, wherein an inlet of the molybdenum trioxide evaporation tank 9 is connected with an argon pressure maintaining tank 5, an outlet of the molybdenum trioxide evaporation tank is connected with a high-speed reduction zone 2, an inlet valve 6 and an outlet valve 11 are respectively arranged on an inlet pipeline and an outlet pipeline of the molybdenum trioxide evaporation tank 9, a pressure detection meter 8 is arranged on the molybdenum trioxide evaporation tank 9, and a blow-off device 7 is arranged on one side, opposite to the outlet, of the molybdenum trioxide evaporation tank 9;
referring to fig. 2 and 3, the rapid reduction zone 2 of the present invention is a microchannel reactor 12 with an inlet end connected to an outlet of a molybdenum trioxide evaporation tank 9 and an outlet end connected to a cooling and collecting zone 3, the inlet of the microchannel reactor 12 is a conical airflow buffer 122 with an inverted conical structure, a plurality of microchannels 125 with diameters of 10-1000 μm are arranged at the rear end of the conical airflow buffer 122 along the circumference of a concentric circle, a support rod 124 is arranged at the center of the microchannel reactor 12, the innermost microchannels 125 are arranged along the circumference of the support rod 124, a tubular hydrogen gas distributing bin 123 with a hydrogen valve 16 which is communicated with a hydrogen gas and water vapor separation and buffer tank 17 is arranged between each layer of microchannels 125, and a plurality of micropores which are communicated are uniformly arranged on the tangent line of each microchannel 125 and the inner wall of the tubular hydrogen gas distributing bin 123;
the cooling and collecting area 3 comprises a cooling and collecting device 13 and absolute ethyl alcohol arranged in the cooling and collecting device 13, the outlet of the micro-channel reactor 12 extends into the absolute ethyl alcohol, and a stirring device 15 is arranged in the cooling and collecting device 13;
the cooling and collecting device 13 is also connected with the recovery zone 4, and the recovery zone 4 comprises a gas, water and ethanol separator and a hydrogen-argon separator which are respectively connected with the argon pressure maintaining tank 5, the hydrogen and water vapor separation and buffer tank 17.
The gas phase reduction and collection method of the narrow-distribution superfine molybdenum powder comprises the following steps:
1) Stable sublimation of gas-phase molybdenum source
2) Gas phase mixing and rapid reduction
MoO from molybdenum Source stabilization sublimation zone 1 3 The temperature of the steam 121 is about 900 ℃, the steam enters the microchannel reactor 12, a conical airflow buffer 122 is arranged at the inlet of the microchannel reactor 12 and is used as a molybdenum trioxide steam airflow buffer area, so that the pressure and the speed of the molybdenum trioxide steam 121 entering each microchannel 125 are the same, hydrogen enters the microchannel 125 from the hydrogen and water steam separation and buffer tank 17 into the tubular hydrogen gas distribution bin 123 through micropores, and enters the gas phase MoO with the axis of the microchannel 125 3 Forming vertical cross air flow, realizing the reaction condition that the gas-phase molybdenum source and hydrogen are uniformly mixed instantaneously and completely in the time and space, and generating superfine molybdenum powder with narrow particle size distribution through uniform mixing and rapid reduction;
3) Cooling and collecting superfine molybdenum powder
Ultrafine molybdenum powder with narrow particle size distribution generated by reduction flows out from the other side of the micro-channel reactor 12 under the action of gas pressure, is led into absolute ethyl alcohol of the cooling and collecting device 13 through a pipeline at the outlet of the micro-channel reactor 12, breaks up generated bubbles through the stirring device 15, increases the contact area between the bubbles and collecting liquid, namely absolute ethyl alcohol, so that molybdenum powder particles are cooled and collected, and molybdenum powder particles in the bubbles are remained in the collecting liquid at the moment; vapor and excessive hydrogen generated by gas phase reduction are discharged out of the cooling and collecting device 13 along with bubbles, and a collecting liquid containing molybdenum powder particles is dried in an argon environment to obtain superfine molybdenum powder;
the superfine molybdenum powder can be stored and transported through organic matters with better thermal stability by means of the compatibility of alcohol and organic matters;
4) Recycling and utilization
The unreacted water vapor, hydrogen and argon are returned to the corresponding hydrogen and water vapor separation and buffer tank 17 and argon pressure maintaining tank 5 for recycling through the gas, water and ethanol separators and the hydrogen-argon separators.
The invention utilizes the principle of a micro-channel reactor to uniformly supply the concentration of the gas-phase molybdenum oxide through micro-channels uniformly distributed on the cross section of the reaction zone; the hydrogen is uniformly input through the air holes which are axially and uniformly distributed in the micro-channel. The uniform overall temperature of the microchannel reducer is achieved by employing highly thermally conductive metals such as molybdenum, copper and their molybdenum-copper alloys.
In the traditional reactor, the reaction process is affected by mass transfer speed to a certain extent, the reaction is sequential, the time is not uniform, and the degree is different. Thus, the product exhibits a broad particle size distribution. The narrow channel shortens the transfer time and the transfer distance of reactants through the reduction of the microchannel reactor, has strong mass transfer characteristic, obviously enhances the molecular diffusion, and has consistent reaction duration and narrow product uniformity distribution.
The molybdenum oxide is uniformly mixed with molecular level by gas phase and hydrogen, the reaction speed is high, and the energy consumption is low.
Claims (10)
1. A narrow-distribution superfine molybdenum powder gas-phase reduction and collection device is characterized in that: comprises a molybdenum source stable sublimation zone (1), a rapid reduction zone (2) and a cooling and collecting zone (3) which are communicated in sequence;
the molybdenum source stable sublimation zone (1) comprises a molybdenum trioxide evaporation tank (9) with an inlet connected with an argon pressure maintaining tank (5) and an outlet connected with the rapid reduction zone (2) and used for evaporating molybdenum trioxide;
the rapid reduction zone (2) is a micro-channel reactor (12) with an inlet end connected with an outlet of the molybdenum trioxide evaporation tank (9), an outlet end connected with the cooling and collecting zone (3), and the micro-channel reactor (12) consists of a tubular hydrogen distribution bin (123), a central support rod (124) and a micro-channel (125); the tubular hydrogen gas distribution bin (123) is of a concentric multi-layer structure, a plurality of micro-channels (125) are distributed among each tubular hydrogen gas distribution bin (123) along the circumference of each concentric circle, a plurality of small holes are uniformly distributed on the tangent line of the inner wall of each tubular hydrogen gas distribution bin (123) and the micro-channels (125), a plurality of small holes are uniformly distributed on the tangent line of each micro-channel (125) and the inner side of the tubular hydrogen gas distribution bin (123), the tubular hydrogen gas distribution bin (123) corresponds to the small holes on the micro-channels (125), and hydrogen enters the micro-channels (125) from the tubular hydrogen gas distribution bin (123) through the small holes under the action of pressure;
the cooling and collecting area (3) comprises a cooling and collecting device (13) and absolute ethyl alcohol arranged in the cooling and collecting device, and the outlet of the micro-channel reactor (12) extends into the absolute ethyl alcohol.
2. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: the inlet and outlet pipelines of the molybdenum trioxide evaporation tank (9) are respectively provided with an inlet valve (6) and an outlet valve (11).
3. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: the molybdenum trioxide evaporation tank (9) is provided with a pressure detection meter (8).
4. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: a blow-off device (7) is arranged on one side of the molybdenum trioxide evaporation tank (9) opposite to the outlet.
5. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: the inlet of the microchannel reactor (12) is a conical airflow buffer (122) with an inverted conical structure.
6. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: the microchannel reactor (12) is provided with a support rod (124) at the center, the microchannels (125) of the innermost layer are circumferentially arranged along the support rod 124, and the diameter of the microchannels (125) is 10-1000 μm.
7. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: and a stirring device (15) is arranged in the cooling and collecting device (13).
8. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: the hydrogen valve (16) is arranged on a road where the hydrogen and water vapor separation and buffer tank (17) is communicated with the tubular hydrogen distribution bin (123).
9. The narrow-distribution ultrafine molybdenum powder vapor phase reduction and collection device according to claim 1, wherein: the cooling and collecting device (13) is also connected with the recovery area (4), and the recovery area (4) comprises a gas, water and ethanol separator and a hydrogen-argon separator which are respectively connected with the argon pressure maintaining tank (5), the hydrogen and water vapor separation and buffer tank (17).
10. A method for gas phase reduction and collection of narrow distribution ultra-fine molybdenum powder by the apparatus according to any one of claims 1-9, characterized in that:
1) Stable sublimation of gas-phase molybdenum source
High purity MoO 3 Placing the mixture in a molybdenum trioxide evaporation tank (9), opening an argon pressure maintaining tank (5) and discharging the mixture through vacuumThe air in the molybdenum trioxide evaporation tank (9) is replaced by a gas and gas replacement mode, the furnace temperature is increased to 900 ℃ under the protection of argon, and when the positive pressure in the furnace is more than or equal to 50pa, an outlet valve (11) and a blower (7) are opened, and sublimated MoO is obtained 3 Enters a micro-channel reactor (12) under the driving of air flow;
2) Gas phase mixing and rapid reduction
Simultaneously, hydrogen enters the micro-channel (125) from the tubular hydrogen distribution bin (123) through the micropores and enters the gas phase MoO with the axis of the micro-channel (125) 3 Forming vertical cross air flow, realizing the reaction condition that the gas-phase molybdenum source and hydrogen are uniformly mixed instantaneously and completely in the time and space, and generating superfine molybdenum powder with narrow particle size distribution through uniform mixing and rapid reduction;
3) Cooling and collecting superfine molybdenum powder
Ultrafine molybdenum powder with narrow particle size distribution generated by reduction flows out from the other side of the microchannel reactor (12) under the action of gas pressure, is led into absolute ethyl alcohol of a cooling and collecting device (13) at the outlet of the microchannel reactor (12) through a pipeline, breaks up generated bubbles through a stirring device (15), increases the contact area between the bubbles and collecting liquid, namely the absolute ethyl alcohol, so that molybdenum powder particles are cooled and collected, and molybdenum particles in the bubbles are remained in the collecting liquid at the moment; vapor and excessive hydrogen generated by gas phase reduction are discharged out of a cooling and collecting device (13) along with bubbles, and a collecting liquid containing molybdenum powder particles is dried in an argon environment to obtain superfine molybdenum powder;
4) Recycling and utilization
The unreacted water vapor, hydrogen and argon are returned to the corresponding hydrogen and water vapor separation and buffer tank (17) and argon pressure maintaining tank (5) for recycling through the gas, water and ethanol separators and the hydrogen-argon separators.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3062638A (en) * | 1961-05-03 | 1962-11-06 | Union Carbide Corp | Ultrafine metal powders |
| CN102632249A (en) * | 2012-03-29 | 2012-08-15 | 洛阳开拓者投资管理有限公司 | Method for preparing metal molybdenum powder |
| CN107262733A (en) * | 2017-08-02 | 2017-10-20 | 北京科技大学 | A kind of method that two-part reduction prepares ultrafine molybdenum powder |
| CN114606479A (en) * | 2022-03-11 | 2022-06-10 | 西安交通大学 | Molybdenum vapor deposition molding integrated device and method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3062638A (en) * | 1961-05-03 | 1962-11-06 | Union Carbide Corp | Ultrafine metal powders |
| CN102632249A (en) * | 2012-03-29 | 2012-08-15 | 洛阳开拓者投资管理有限公司 | Method for preparing metal molybdenum powder |
| CN107262733A (en) * | 2017-08-02 | 2017-10-20 | 北京科技大学 | A kind of method that two-part reduction prepares ultrafine molybdenum powder |
| CN114606479A (en) * | 2022-03-11 | 2022-06-10 | 西安交通大学 | Molybdenum vapor deposition molding integrated device and method |
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