CN106186084B - Glucose auxiliary electrostatic spinning low-temperature bake method prepares Ca-Ti ore type LaCoO3 - Google Patents
Glucose auxiliary electrostatic spinning low-temperature bake method prepares Ca-Ti ore type LaCoO3 Download PDFInfo
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- CN106186084B CN106186084B CN201610545762.9A CN201610545762A CN106186084B CN 106186084 B CN106186084 B CN 106186084B CN 201610545762 A CN201610545762 A CN 201610545762A CN 106186084 B CN106186084 B CN 106186084B
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- C01G51/00—Compounds of cobalt
- C01G51/40—Cobaltates
- C01G51/70—Cobaltates containing rare earth, e.g. LaCoO3
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Abstract
The present invention discloses a kind of glucose auxiliary electrostatic spinning low-temperature bake method and prepares Ca-Ti ore type LaCoO3.It is characterized in that：With N, N-dimethylformamide（DMF）The dissolving of glucose, lanthanum nitrate, cobalt nitrate and polyvinylpyrrolidone (PVP) is obtained into precursor solution, solution is obtained into composite nano fiber by electrostatic spinning again, finally composite nano fiber is calcined at low temperature and directly obtains Ca-Ti ore type LaCoO3；Described method adds appropriate glucose when solution is prepared, and has both played the effect for preventing that solution is rotten, plays again and promotes Ca-Ti ore type LaCoO in low-temperature bake3The effect of Crystallization；Described method sintering temperature can as little as 500 DEG C.The Ca-Ti ore type LaCoO prepared using this method3Crystallinity is high, and temperature needed for formation perovskite is relatively low, and raw material is easy to get, and technique is simple, can reduce Ca-Ti ore type LaCoO3Cost is prepared, is advantageous to its popularization and application.
Description
Technical field
The present invention relates to a kind of preparation method of perofskite type oxide, particularly one kind to adopt using glucose as adjuvant
With electrospinning process, roasting at a lower temperature prepares Ca-Ti ore type LaCoO3Method.
Background technology
Perofskite type oxide refers to available formula ABO3A series of oxides represented.A and B refer to two kinds of metals from
Son, O represent oxonium ion.A positions are usually lanthanide series, alkali metal or alkali earth metal；B positions are usually transition metal member
Element.Perofskite type oxide has unique design feature and physicochemical property, since the 1950s, has become catalysis
The study hotspot in the fields such as agent, sensor, solid fuel cell.But this relatively low problem of specific surface area seriously limits calcium titanium
The application of ore deposit type oxide, the especially application in catalytic field.The synthesis temperature of perofskite type oxide is higher, easily causes
Sintering phenomenon occurs for nanosized perovskite-type oxide, is a low major reason of its specific surface area.Improve existing synthesis side
Method uses new synthetic method, so as to reduce the crystallization temperature of perofskite type oxide, has important research and answers
It is one of direction that researcher is made great efforts with meaning.
In 19 century 70s, solid phase method is to synthesize the conventional method of perofskite type oxide, and this method is usually with gold
Belong to oxide be raw material, it is necessary in temperature more than 1000 DEG C the progress long period calcining, it is purer just to obtain crystalline phase
Perofskite type oxide, but at such high temperatures, for material there occurs serious agglomeration, crystallite dimension is larger, than
Surface area is very low, typically in 2 m2/ below g.To the eighties in 19th century, researcher starts using liquid phase method synthesis calcium titanium
Ore deposit type oxide, this method are to dissolve soluble-salt in the solution, drying and calcining, Ca-Ti ore type oxidation are made
Thing.Dissolving metal salts in the solution, form homogeneous solution, and Ca-Ti ore type oxidation can be synthesized at 600 DEG C~900 DEG C
Thing, the reduction of crystallization temperature, the growth of its crystal grain can be suppressed, so as to keep large specific surface area.Generally use liquid phase method synthesizes
Perovskite specific surface area be 0.5~20 m2/g.Common liquid phase method has：Coprecipitation, complexometry, sol-gal process, freezing
Seasoning and spray drying process etc..In recent years, reaction ball milling method, also known as high-energy ball milling method or mechanical alloying method, can be in room
Temperature（Local heating caused by friction is at 180 DEG C~300 DEG C）Lower synthesis perofskite type oxide, has obtained extensive concern.Instead
The temperature that should be synthesized substantially reduces, and effectively suppresses the growth of perofskite type oxide crystal grain, so as to be obviously improved its surface area,
The specific surface area for the perovskite for showing to prepare by reaction ball milling method is studied in 20 m2/ more than g, by optimizing ball milling condition,
Or some additives are added in mechanical milling process（Such as：NaCl or ZnO）The reference area of perovskite can further be lifted extremely
80 m2/ more than g.But this method needs for a long time（>12 h）And at high speed（1000 rpm）Ball milling condition, therefore to equipment
It is required that higher, cost is also higher.
Method of electrostatic spinning is simple, easily operated because having the advantages that, is to prepare one of effective method of nanofiber, recently
Several years study hotspots for turning into synthesis Ca-Ti ore type nanofiber.However, the purer perovskite of crystalline phase is synthesized still using the method
So need higher calcining heat (most of more than 600 DEG C).In addition, this seminar experiment find, only with nitrate,
PVP (polyvinylpyrrolidone) is raw material, can be by method of electrostatic spinning with DMF (DMF) for solvent
The higher Ca-Ti ore type LaCoO of crystallinity is made under relatively low sintering temperature3.However, prepared in electrostatic spinning precursor solution
During, if solution contacts longer time with air contact, solution can slowly go bad so that script viscosity is larger, in purplish red
The solution of color, slowly becomes that viscosity is low, in the liquid (see accompanying drawing 1) of black, causes electrostatic spinning to fail.
The content of the invention
In view of the above problems, it is an object of the invention to provide a kind of Ca-Ti ore type LaCoO3Preparation method --- Portugal
Grape sugar auxiliary electrostatic spinning-low-temperature bake method, this method can prevent electrostatic spinning precursor solution from going bad, and and can is relatively low
Sintering temperature under（As little as 500 DEG C）Obtain the higher Ca-Ti ore type LaCoO of crystallinity3。
To realize that the purpose of the present invention is as follows using technical scheme：
(1) by lanthanum nitrate [La (NO3)3], cobalt nitrate [Co (NO3)2] and polyvinylpyrrolidone (PVP) and N, N- diformazan
Base formamide (DMF) solvent mixes, and at room temperature, carries out magnetic agitation, after solid dissolves substantially, prepares electrostatic spinning forerunner
Liquid solution A；
(2) toward step（1）Electrostatic spinning precursor solution A add glucose (C6H12O6), continue to stir, finally give
Homogeneous precursor solution B；
(3) composite nano fiber is made using method of electrostatic spinning in the precursor solution B that step (2) is prepared, it is prepared
Composite nano fiber, which is placed in drier, places 12 h；
(4) composite nano fiber prepared by step (3) is placed in Muffle furnace, is calcined, obtained in air atmosphere
Ca-Ti ore type LaCoO3。
It is preferred that step (1) the ratio between amount of material of lanthanum nitrate and cobalt nitrate n in solution processes are prepared1：n2=1:1, nitre
Volume (mL) ratio of hydrochlorate gross mass (g) and solvent DMF is 0.03~0.04:1.
It is preferred that step (2) add glucose reagent as adjuvant, the amount n of the material of the glucose added3For
The amount n of the material of lanthanum nitrate12.0~4.0 times, to prevent the rotten of solution（Solution blackening, viscosity decline, and electrostatic spinning is difficult
To carry out）, while promote the formation of perovskite crystal formation.
It is preferred that volume (mL) ratio that step (1) prepares PVP mass (g) and solvent DMF in solution is：0.075~
0.125:1。
It is preferred that the voltage used during step (3) electrostatic spinning during electrostatic spinning for 20~25 kV, is fed
Speed is 0.7~1.0 mL/h, and temperature is 40~45 DEG C, and stainless steel syringe needle internal diameter be 0.7~1 mm, receive distance be 13~
18 cm, it is 8~10 h to continue the electrospinning time.
It is preferred that the heating rate in step (4) composite nano fiber roasting process is 2~10 DEG C/min, constant temperature is calcined
Temperature is 500~1000 DEG C, and roasting constant temperature time is 4~7 h.
It can be seen from the above technical scheme that the present invention has the advantages that：
(1) this method can under relatively low sintering temperature (500 DEG C) synthesis perofskite type oxide LaCoO3；
(2) glucose is added in electrostatic spinning precursor solution, as adjuvant, can prevents precursor solution from becoming
Matter, and cause electrostatic spinning to be difficult to, it can also promote Ca-Ti ore type LaCoO3Formation；
(3) it is easy to operate to prepare perofskite type oxide for this method, can simplify preparation technology, saves the energy.
Brief description of the drawings
Fig. 1 is the electrostatic spinning precursor solution for not adding glucose (A in Fig. 1) and adding glucose (B in Fig. 1)
The color change of different mixings time compares figure.
Fig. 2 is the XRD spectra (different synthetic methods) of the sample prepared by embodiment 1.
Fig. 3 is the XRD spectra (different glucose dosages) of the sample prepared by embodiment 2.
Fig. 4 is the XRD spectra (difference roasting thermostat temperature) of the sample prepared by embodiment.
Embodiment
To be best understood from the present invention, the present invention is described further with reference to embodiment, but application claims
The scope of protection is not limited to the scope of embodiment expression.
Embodiment 1 (different synthetic methods)
Using glucose auxiliary electrostatic spinning-low-temperature bake method synthesis LaCoO3(4.0 times of glucose)：
1) 0.3589 g La (NO are weighed3)3·nH2O and 0.3215 g Co (NO3)2·6H2O is in 50 mL conical flask
In (the ratio between amount of material of lanthanum nitrate and cobalt nitrate n1：n2=1:1), and 2.000 g PVP and 20 mL DMF solutions are added,
At room temperature, the h of magnetic agitation about 2, makes solid matter dissolve substantially, and solution is in aubergine, homogeneous liquid, labeled as molten
Liquid A.
2) 0.8757 g glucose is weighed, adds solution A (the amount n of glucose substance3For the amount n of lanthanum nitrate material1's
4.0 times), and magnetic agitation is constantly carried out, about 4 h, all dissolved to solid, obtain solution B.
3) solution B is subjected to electrostatic spinning, setting feed speed is 1.0 mL/h, 43 DEG C of temperature, the use of internal diameter is 1 mm
Stainless steel syringe needle, apply 23.0 kV voltage in syringe needle bottom, and aluminium-foil paper spread at 15 cm immediately below it, for connecing
Receive.After electrostatic spinning persistently carries out 10 h, take out sample and be placed on the h of room temperature preservation 12 in drier.
4) the composite nano fiber sample after aluminium-foil paper will be removed to be placed in crucible, be put into Muffle furnace, with 5 DEG C/min
Heating rate rise to 500 DEG C and the h of constant temperature 4 from room temperature, obtain LaCoO3Sample.
In order to be compared, the LaCoO for not adding glucose is prepared using synthetic method same as described above3Sample, close
The place different into process be to carry out isolation air-treatment to the solution of step 1), prevents solution from going bad, and skips over step 2),
Remaining step is completely the same；In addition, LaCoO is synthesized using sol-gal process3Sample, specific building-up process are as follows：Weigh
0.3589 g La(NO3)3·nH2O and 0.3215 g Co (NO3)2·6H2O is dissolved in 15 mL distilled water, obtains C solution；
Weigh 0.8757 g glucose to be dissolved in 5 mL distilled water, obtain solution D；It is molten that C is added dropwise in solution D under 60 DEG C of water-baths
In liquid, and stir 30 min and obtain E solution；E solution is dried into 10 h under conditions of 80 DEG C and obtains xerogel.By xerogel
It is placed in crucible, 500 DEG C of 4 h of temperature roasting is risen to 5 DEG C/min heating rate in Muffle furnace.
Fig. 1 is the electrostatic spinning precursor solution for not adding glucose (A in Fig. 1) and adding glucose (B in Fig. 1)
The color change of different mixings time compares figure.From the A in Fig. 1 it can be found that the solution for not adding glucose (is not completely cut off
Air-treatment) after solid dissolves substantially (about 2 h), continue stirring a period of time (about 4 h) solution colour and deepen, finally about 6
After h, solution becomes black, and color change is to black from aubergine to peony；The viscosity of solution is also decreased obviously so that
Electrostatic spinning is difficult to；And from the B in Fig. 1 it can be found that add glucose in solution, it is stirred in same case molten
Liquid, the color and viscosity of solution are all aubergines without obvious change.This illustrates that glucose rises in the process for preparation of solution
Protective effect has been arrived, can prevent solution from going bad.
Fig. 2 is the XRD spectra of the sample prepared by embodiment 1, from the figure, it can be seen that the condition of the roasting at 500 DEG C
Under, using the LaCoO of sol-gal process synthesis3Appearance is weaker, and its crystallinity is relatively low, and nearby occurs 2 θ=30 ° and 35 °
Some miscellaneous peaks, its crystalline phase purity are relatively low；Using the LaCoO synthesized by method of electrostatic spinning (not adding glucose)3, appearance is stronger,
Each appearance can be well matched with standard card (JCPSD No.48-0123), and crystallinity is preferable, and crystalline phase is purer；And use grape
Sugared auxiliary electrostatic spinning-low-temperature bake method synthesis LaCoO3, go out that peak intensity is stronger, and its crystallinity is more preferable, and crystalline phase is purer.Therefore,
Glucose is added during electrostatic spinning, Ca-Ti ore type LaCoO can be promoted under relatively low calcining heat3Formation.
Embodiment 2 (different glucose dosages)
LaCoO is synthesized using with glucose auxiliary electrostatic spinning-low-temperature bake method in embodiment 13Consistent synthesis step,
It is respectively synthesized the LaCoO of different glucose dosages3, the difference of building-up process be the dosage of glucose be respectively 2.5 times (i.e.
0.5473 g) and 3.0 times (i.e. 0.6568 g).
Fig. 3 is the XRD spectra of the sample prepared by embodiment 2, from the figure, it can be seen that the condition of the roasting at 500 DEG C
Under, crystalline phase purer Ca-Ti ore type LaCoO higher using different amounts of glucose energy synthetic crystallization degree3, the increasing of glucose dosage
Add, it goes out peak intensity and continues to strengthen, and crystallinity further improves.
Embodiment 3 (difference roasting thermostat temperature)
LaCoO is synthesized using with glucose auxiliary electrostatic spinning-low-temperature bake method in embodiment 13Consistent synthesis step,
It is respectively synthesized the LaCoO of different roasting thermostat temperatures3, the difference of building-up process be to be calcined thermostat temperature be respectively 600 DEG C,
700 DEG C, 800 DEG C and 1000 DEG C.
Fig. 4 is the XRD spectra of the sample prepared by embodiment 3, as we can see from the figure in different roasting thermostat temperatures
Under, can be higher with synthetic crystallization degree, the purer Ca-Ti ore type LaCoO of crystalline phase3, and with the rise of roasting thermostat temperature, its sample
Product go out that peak intensity is more and more stronger, and crystallinity significantly improves.
Claims (6)
1. a kind of glucose auxiliary electrostatic spinning-low-temperature bake method prepares Ca-Ti ore type LaCoO3, it is characterised in that including as follows
Step：
(1) by lanthanum nitrate [La (NO3)3], cobalt nitrate [Co (NO3)2] and polyvinylpyrrolidone (PVP) and N, N- dimethyl formyl
Amine (DMF) solvent mixes, and at room temperature, carries out magnetic agitation, after solid dissolves substantially, prepares electrostatic spinning precursor solution
A；
(2) glucose (C is added toward the electrostatic spinning precursor solution A of step (1)6H12O6), continue to stir, finally give homogeneous
Precursor solution B；
(3) composite nano fiber is made using method of electrostatic spinning in the precursor solution B that step (2) is prepared, prepared is compound
Nanofiber, which is placed in drier, places 12 h；
(4) composite nano fiber prepared by step (3) is placed in Muffle furnace, is calcined in air atmosphere, obtains calcium titanium
Ore deposit type LaCoO3。
2. glucose auxiliary electrostatic spinning-low-temperature bake method as claimed in claim 1 prepares Ca-Ti ore type LaCoO3, its feature
It is：The ratio between described lanthanum nitrate and the amount of material of cobalt nitrate n1:n2=1:1, nitrate gross mass g and solvent DMF volume
ML ratios are 0.03~0.04:1.
3. glucose auxiliary electrostatic spinning-low-temperature bake method as claimed in claim 1 or 2 prepares Ca-Ti ore type LaCoO3, it is special
Sign is：The amount n of the material of described glucose3For the amount n of the material of lanthanum nitrate12.0~4.0 times.
4. glucose auxiliary electrostatic spinning-low-temperature bake method as claimed in claim 1 or 2 prepares Ca-Ti ore type LaCoO3, it is special
Sign is：Described PVP mass g and the volume mL ratios of solvent DMF are：0.075~0.125:1.
5. glucose auxiliary electrostatic spinning-low-temperature bake method as claimed in claim 3 prepares Ca-Ti ore type LaCoO3, its feature
It is：Described electrospinning conditions are that voltage is 20~25 kV, and charging rate is 0.7~1.0 mL/h, and temperature is 40~45
DEG C, stainless steel syringe needle internal diameter is 0.7~1 mm, and it is 13~18 cm to receive distance, and it is 8~10 h to continue the electrospinning time.
6. glucose auxiliary electrostatic spinning-low-temperature bake method as claimed in claim 4 prepares Ca-Ti ore type LaCoO3, its feature
It is：Described composite nano fiber roasting parameter is that heating rate is 2~10 DEG C/min, roasting thermostat temperature is 500~
1000 DEG C, roasting constant temperature time is 4~7 h.
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| CN108658132B (en) * | 2018-07-10 | 2019-08-27 | 厦门大学 | Nitrate assists citric acid complex method low temperature to synthesize Ca-Ti ore type LaCoO3 |
| CN110184682B (en) * | 2019-05-31 | 2021-08-10 | 福建师范大学 | Preparation of perovskite LaCoO3Low temperature calcination method of |
| CN116550336B (en) * | 2023-07-10 | 2023-09-22 | 内蒙古工业大学 | Pd doped perovskite oxide nanofiber as well as preparation method and application thereof |
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| CN101235556A (en) * | 2008-03-12 | 2008-08-06 | 长春理工大学 | Method for preparing perovskite-type rare earth composite oxide ultra-long nano fiber |
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