A kind of method for preparing the nanometer molybdic oxide
Technical field
The present invention relates to the non-ferrous metallurgy technology field, especially relating to a kind of is the method for feedstock production nanometer molybdic oxide with pure molybdic oxide.
Background technology
Molybdic oxide is a most important midbody in the molybdenum metallurgy, and the compound of most of molybdenums is that raw material makes with it directly or indirectly all, and molybdic oxide all is widely used in fields such as catalyzer, display unit, transmitter, dynamo batteries.
Generally produce molybdic oxide in the industry with the method for calcination ammonium molybdate; Continuous development along with Materials science and utilisation technology; The molybdic oxide that this method makes since particle thick, be aggregating state and can not satisfy special request for utilization; In CN102198958, disclose the preparation method of a kind of oil Hydrobon catalyst with high-purity molybdic oxide like Guo Guanghua etc., ammonium tetramolybdate is dry, send into the return bend electric furnace after sieving and carry out roasting, the one-pass finished rate reaches 98.5%.
Because molybdic oxide promptly has significant vp under lower temperature; So can purify molybdic oxide with subliming method; Under the operational condition of distillation, symbiotic with it usually impurity or do not have volatility (like silicate etc.) or can not condensation and be removed.
At present; To produce the main raw material of pure molybdic oxide be that industrial molybdenum oxide is the molybdenum calcining to subliming method in the industry, low according to molybdenum oxide fusing point in the molybdenum calcining, boiling point, when temperature is lower than 795 ℃ of its fusing points, begins distillation; Form with the trimerization molybdenum oxide gets into gas phase; The molybdic oxide steam together gets in the fan housing that gathers dust together with air and under the draft effect, gets into cloth bag and collects, and most of impurity compound is much stayed in the solid phase because of fusing point, boiling point height, and distillation is carried out in the rotation electric furnace; Sublimation temperature generally is controlled at 900~1100 ℃, and the general purity of the molybdic oxide of producing can reach MoO
399.8% (Zhang Qixiu, Zhao Qinsheng chief editor, " tungsten is metallurgical ", in September, 2005); The researchist of Korea S invents a kind of novel subliming furnace, and the subliming furnace throughput at the bottom of this stove ratio band rotary oven is big, energy consumption low (opening civilian bell-shaped percussion instrument, used in ancient time by troops on march, molybdenum oxide research and development progress, " China molybdenum already ", 2006 the 1st phases); US4551313 discloses a kind of quick sublimation method that contains into the molybdic oxide of slag ingredient (silicon, aluminium and heavy metal); The first step: molybdenum oxide particle, the fuel that passes through the nozzle conveying and the oxygen-containing gas mixed flow carried through pneumatic suspension stream get in the sealing furnace chamber; Fuel gas mixture is lighted and is produced the be enough to flame that makes molybdic oxide distillation, be melted into slag ingredient of temperature 200 ℃~1800 ℃ of 1600 scholars; Collect the liquid slag in the furnace chamber, second step: the gas and the suspended solids of the molybdic oxide that comprises distillation that will produce get into a condensing chamber through above-mentioned furnace chamber, the temperature of condensing chamber (850~950 ℃) be higher than the molybdic oxide of distillation condensing temperature, be lower than the volatilization temperature of volatile metal impurity; Condensation then (150~500 ℃), collect solid-state molybdic oxide; Separate waste gas, thereby realize molybdic oxide and separate impurities, the result shows; The molybdenum of sneaking in the slag is lower than 1%, obtains product molybdic oxide purity and reaches MoO
399.95%.
Although adopt above-mentioned these methods can obtain the molybdic oxide of higher degree, but still have following several problem: 1, molybdenum recovery is starkly lower than 75%, has offset product purity and improved the advantage of bringing; 2, owing in stove, feed a large amount of airflows, most of heat is not to be used for the product that distils, but is used to improve the temperature of introducing air; 3, the product molybdic oxide mean particle size that makes can not satisfy the particular requirement in fields such as Materials science at micron order.
Have and discover to have anisotropic nanometer molybdic oxide, more demonstrate its special catalytic performance; Can be widely used as catalyzer, conventional subliming method adopts gather dust fan housing and cloth bag collection molybdic oxide, because of the particle coacervation only obtains the micron order product; In order to produce the nanometer molybdic oxide; Must the hurried cooling of molybdic oxide gas of distillation be prevented coacervation of molybdic oxide particle or reunion, thereby obtain the nano level product.
US6468497 discloses a kind of working method of nanometer molybdic oxide; Adopt distillation-quenching method to produce the nanometer molybdic oxide industrial molybdenum oxide; Production technique is following: the industrial molybdenum oxide powder (being made up of molybdic oxide and molybdenum dioxide usually) of about 24~260 μ m of granularity is sent in the subliming furnace through controlled worm conveyer; Blast air through inlet and make molybdenum dioxide be oxidized to molybdic oxide, subliming furnace heats with electric power, detects temperature in the stove with thermopair; When furnace temperature reached 1100 ℃, molybdic oxide began distillation and is deposited on like in the membranaceous feed-pipe; The nanometer molybdic oxide that has distilled is used the liquid nitrogen stream quenching; Get into hopper, inflow filter then is through blower fan sucking-off cold air; Nanometer molybdic oxide product is discharged through funnel; The reaction sublimation temperature is 1093~1260 ℃, and the activity duration of subliming furnace is 120min, but long approximately 100 nm of output, wide 25 nm, high 20 nm be strip nano level molybdic oxide.
Though aforesaid method can make the nano level product, the problem that exists is: the distillation time is long, generally more than 120min, can not carry out serialization production.
A kind of molybdenum oxide plasma physics of propositions such as Zhao Qinsheng vapour deposition process is produced the method for high-purity molybdic oxide; Handle commercially pure molybdenum oxide (being the molybdenum calcining) with air plasma; Utilize the molybdic oxide boiling point characteristics lower than most of impurity; Make its volatilization rapidly in the air plasma flame, outside flame passes, introduce a large amount of freezing airs then and make the quenching of gaseous state molybdic oxide, obtain ultra-fine high-purity molybdic oxide powder.Because employing plasma method; Estimate that the PT can shorten greatly; But this method: 1, for guaranteeing the rapid volatilization of molybdic oxide under condition of plasma, flame passes must keep comparatively high temps (more than 2000 ℃), causes most of impurity in raw material molybdenum calcining entering gas phase of also volatilizing; Final condensation also follows molybdic oxide to get in the product, influences product purity; 2, this method only is an imagination, no industrial application, even do not have experimental installation (Zhang Qixiu, Zhao Qinsheng chief editor, " tungsten is metallurgical ", in September, 2005).
Summary of the invention
On the basis of existing technology, the object of the present invention is to provide a kind of is the method for raw material using plasma sublimation production nanometer molybdic oxide with pure molybdic oxide, the ultrashort time, can realize robotization, serialization production.
A kind of method for preparing the nanometer molybdic oxide is a raw material with pure molybdic oxide, through plasma body sublimation production nanometer molybdic oxide, it is characterized in that:
Pure molybdic oxide powder is sent in the plasma body subliming furnace through feeding device, in plasma flow, distilled, running time 10~100ms, the gaseous state molybdic oxide of acquisition adopts the quenching medium quenching, and material collecting device is collected, and obtains the nanometer molybdic oxide, MoO
3>99.80%.
Sublimation condition is: 2000~10000 ℃ of temperature, vacuum tightness are 10
3~10
5Little negative pressure of Pa.
Further, said quenching medium is water, air or liquid nitrogen.
Further, said nanometer molybdic oxide granularity≤80nm.
Further, the plasma gas that produces said plasma flow is argon gas, nitrogen, air, oxygen or other suitable gas.
The alleged pure molybdic oxide of the present invention refers to the pure molybdic oxide that adopts ammonium molybdate pyrolysis or additive method to make, and its chemical constitution meets corresponding industry standard.
Adopt aforesaid technical scheme, the present invention has following beneficial effect at least:
1, ultrahigh-temperature is brought the ultrashort time
Among the present invention; Because the ultrahigh-temperature of plasma body heating; When molybdic oxide powder entering plasma body subliming furnace, the transmission of in the extremely short time, promptly accomplishing heat reaches the abundant heating to powder, but distillation operation moment completion (≤100ms); Ultrahigh-temperature is brought the ultrashort time, obviously is superior to existing distillation or distillation-quench technique;
2, realize robotization, serialization production
Because the present invention replaces existing rotation electric furnace or novel subliming furnace with the plasma body subliming furnace; Can accomplish the volatilization distillation of molybdic oxide once, fast; Form constantly the serialization production process of feeding in raw material, constantly collecting finished product; Produce molybdic oxide running time length, can not serialization production compare with existing various sublimation methods, present method has really realized robotization, serialization production, produces the nanometer molybdic oxide per year more than 400 tons;
3, product granularity is thin
The present invention adopts quenching to collect the preparation molybdic oxide, has avoided the coacervation or the reunion of molybdic oxide particle, thereby has obtained the nano level product, and product granularity can be controlled in the 80nm, compared with prior art, can satisfy the particular requirement of material science.
Description of drawings
Fig. 1: the processing unit synoptic diagram of preparation nanometer molybdic oxide of the present invention.
Main numbering explanation among the figure: 1 plasma body subliming furnace; 2 receive assorted device; 3 water-cooled collection devices; 4 vacuum systems; 5 plasma gass; 6 cooling systems; 7 power interfaces; 8 feeding devices; 9 material collecting devices; 10 purge gas.
Embodiment
Specify technical scheme of the present invention below in conjunction with accompanying drawing 1 and embodiment, but protection scope of the present invention includes, but are not limited to this:
The processing unit of preparation nanometer molybdic oxide of the present invention is arranged as shown in Figure 1; Distillation is carried out in plasma body subliming furnace 1, and production unit also comprises feeding device 8, material collecting device 9, receives assorted device 2, vacuum system 4, cooling system 6 and water-cooled collection device 3 etc.; Pure molybdic oxide raw material powder is sent in the plasma body subliming furnace 1 through feeding device 8, in 2000~10000 ℃ of plasma flows that plasma gas 5 bright eruptions produce, distilled running time 10~100ms; The molybdic oxide that distillation produces is introduced water-cooled collection device 3, use water as the quenchant quenching, material collecting device 9 is collected, and obtains the nanometer molybdic oxide; Vacuum system 4 system vacuum tightnesss are 10
3~10
5Pa, cooling system 6 is provided with water-in and water outlet; Water-cooled collection device 3 adopts water-cooled pulse backblowing strainer, constantly feeds purge gas 10 under the working order and realizes gas solid separation.
Among the present invention, vacuum degree control is 10
3~10
5Little negative pressure of Pa can obtain extraordinary distillation effect; In the process of distillation molybdic oxide, because the ultra high temp of plasma generation, rate of sublimation is very fast, in the ultrashort time is time of Millisecond, accomplishes.
The concrete operations implementation process is following:
1, opens the water coolant of waterworks 6;
2, close feed valve, the raw material molybdic oxide is added feeding device 8;
3, vacuum system 4 is evacuated down to setting vacuum tightness;
4, feed plasma gas 5, insert the plasma flow that plasma power supply produces design temperature by power interface 7;
5, feed pulse gas 10 to water-cooled collection device 3;
6, open feed valve, continue the material powder in the feeding device 8 is added the operation that distils in the plasma body subliming furnace 1;
7, collect the product molybdic oxide from material collecting device 9, collect impurity from receiving assorted device 2.
Can also make quenching medium with air or liquid nitrogen in the practice.
Embodiment 1:
Raw material: pure molybdic oxide powder, its chemical group prejudice table 1.
Implementation process: pure molybdic oxide raw material is sent in the plasma body subliming furnace, and the temperature of control plasma flow is that 2000~10000 ℃, vacuum tightness are 10
3~10
5Pa uses water as quenchant, and quenching is collected, and obtains molybdic oxide, and sampling detects.
Implement parameter and result and list in table 2.
Can find out from table 2:
1, with MoO
399.82% pure molybdic oxide is a raw material, the using plasma subliming method can 100ms with the interior ultrashort time make purity more than 99.80%, the high-purity nm molybdic oxide of granularity below 80nm;
2, along with the rising of plasma body sublimation temperature, rate of sublimation is accelerated, and vacuum tightness reduces, and production capacity improves.
It should be noted last that: above explanation is only unrestricted in order to explanation the present invention; Although the present invention is specified with reference to preferred embodiments; Those of ordinary skill in the art is to be understood that; Can make amendment or be equal to replacement the present invention, and not break away from the spirit and scope of the present invention, it all should be encompassed in the middle of protection scope of the present invention.
Table 1 raw material chemical constitution
Table 2 embodiment 1 parameter and result