CN101070175A - Method for preparing nano Al2O3 adopting salt-melting calcination process - Google Patents

Abstract

The invention relates to a kind of preparation method of Al2O3 using molten salt auxiliary calcination, which belongs to technique field of chemical industry. It adopts chemical precipitation method in this invention, regards Na2CO3 solution as precipitator, under the condition that the temperature of lukewarm bath is 40 degree C and mix around them fiercely, put Na2CO3 water solution into AlCl3 water solution for two steps with different dripping speed, get gelatinous white deposition, pumping ,filtrating and scrubbing it when aged for some time, dry precursor at temperature of 60, degree C add molten salt nitrate and calcine it in the vacuum drying oven for 0.5-2.0 hours, the calcineing temperature is 350-75 degree C; proportion by weight of precursor and molten salt is 1:6-1:12.Cool the calcineing outcome in the vacuum drying oven, finally get nanophase Al2O3 which is a kind of white powder after abstersion and dryness. We can get products of different grain size and crystal phase through controlling variety and addition of molten salt. The craft of the invention is simple and the product Al2O3 has higher quality.

Description

Adopt the fused salt calcination method to prepare nanometer Al 2O 3Method

Technical field

The present invention relates to a kind of employing fused salt calcination method and prepare nanometer Al ₂O ₃Method, belong to chemical technology neck dirt.

Background technology

Nanometer Al ₂O ₃Owing to have good wearability, corrosion resistance, optical stability, electrical property, catalytic and good biocompatibility, have special purposes in fields such as wear-resisting, insulation, fire-retardant, catalysis, microelectronic elements, become a kind of most widely used, nano material that demand is the most urgent.

Al ₂O ₃A lot of crystal formations are arranged, find at present more than 12 kinds, a-Al wherein ₂O ₃The high-temperature stable phase, other are unsettled transition crystalline phase, at high temperature can change a phase into, by needs more than 1230 ℃.γ is modal low temperature crystal formation mutually, has face-centered cubic lattice, belongs to adopt the spar structure.γ-Al ₂O ₃Have very strong adsorption capacity, have widely in chemical industry, environment and oil field and use.

Tradition preparation nanometer Al ₂O ₃What the powder great majority adopted is vapor phase method and liquid phase method.The advantage of vapor phase method is that reaction condition can be controlled, product is easily exquisite, and particle is tiny, nothing is reunited or few nanometer Al that reunites as long as the kind of control reacting gas and dividing potential drop just can obtain ₂O ₃Particle, such as Chinese patent CN1420082, CN1398787, CN1289723 etc., but, this method requires raw material must be gasified totally before reaction, this need to consume a lot of energy, and needs a large amount of inert gases in the reaction, causes production efficiency low, owing to complex equipment, the reasons such as the collection difficulty of powder are not suitable for large-scale production simultaneously.The remarkable advantage of liquid phase method is: also can obtain the very high nanoparticle of chemical uniformity for very complicated material, and become the end relatively low, output is also bigger, and is easy to prepare, do not need very exacting terms, is fit to scale operation.Such as Chinese patent CN1341559, CN1342609, CN1583567, but the alkoxide of normally used aluminium is expensive, and some needs poisonous organic solvent or could react under the condition of HTHP.The precipitation method are as method the simplest in the liquid phase method, relatively efficient and that can be mass-produced, but most methods will be controlled pH value, and experiment is complicated, the cost height, such as Chinese patent CN1184078, CN1631785 etc., the present invention adopts the precipitation method, utilizes the fused salt ancillary technique to prepare nanometer Al ₂O ₃Powder, this method can shortened process, make equipment investment little, and product cost is low.

Summary of the invention

Purpose of the present invention is providing a kind of by adopting the fused salt calcination method to prepare nanometer Al ₂O ₃The new method of powder.

The auxiliary calcination method of a kind of employing fused salt of the present invention prepares nanometer Al ₂O ₃Method, it is characterized in that having following preparation process and step:

A. prepare certain density AlCl with deionized water ₃And Na ₂CO ₃The aqueous solution is standby; AlCl ₃The concentration of the aqueous solution is 0.2～0.6mol/L, Na ₂CO ₃The concentration of the aqueous solution is 0.8～1.2mol/L;

B. under 30～60 ℃ of waters bath with thermostatic control and violent stirring condition, in two steps with different rate of addition at above-mentioned AlCl ₃The Na of adding effect precipitation agent in the water solvent ₂CO ₃The aqueous solution; The first step adds 60～80% precipitation agent Na at 10～20min with the rate of addition of 600～1000ml/h in the time ₂CO ₃Solution; Second step added remaining precipitation agent Na with slow rate of addition 200～300ml/h at 15～25min in the time ₂CO ₃Solution;

C.Na ₂CO ₃After the aqueous solution dropwises, sustained reaction 30～60min under 30～60 ℃ of condition of water bath heating;

D. with above-mentioned reaction gained contain the white gels shape after sedimentary mother liquor ageing for some time, carry out suction filtration, and adopt deionized water, dehydrated alcohol that throw out is repeatedly washed; Place 40～60 ℃ loft drier dry the precursor that obtains;

E. with the dry precursor of above-mentioned gained and fused salt uniform mixing by a certain percentage; Fused salt is any in NaNO3, KNO3, the LiNO3 nitrate; The part by weight of precursor and fused salt is 1: 6～1: 12; The mixture of thing before above-mentioned and fused salt is placed in the vacuum oven, calcines under 350～700 ℃ of temperature, calcination time is 0.5～2.0h;

F. after cooling to above-mentioned calcined product with the furnace room temperature, again repeatedly wash with absolute ethyl alcohol, deionized water, the fused salt that flush away is unnecessary finally obtains nanometer Al after drying ₂O ₃White powder.

The inventive method utilizes the technology of the auxiliary calcining of fused salt to prepare nanometer Al ₂O ₃Powder, its technology is simple, and is easy to operate, with low cost.

The method that adds the auxiliary calcining of fused salt among the present invention can promote Al ₂O ₃The transformation of crystalline phase.

Description of drawings

Fig. 1 for 350 ℃ of calcinings of precursor of adding different fused salt Li, Na, K nitrate after the XRD figure of final product.

Fig. 2 is for adding NiNO ₃The XRD of end product figure after 550 ℃ of calcinings of the predecessor of fused salt.

Fig. 3 is for adding the TEM figure of the auxiliary calcining of different fused salts after product

Embodiment

After now embodiments of the invention specifically being described in.

Embodiment one: the preparation process of present embodiment is as follows:

(1) with the AlCl of deionized water preparation 0.4mol/L ₃The Na of the aqueous solution and 1mol/L ₂CO ₃The aqueous solution is standby;

(2) with above-mentioned Na ₂CO ₃The aqueous solution is as precipitation agent, under 40 ℃ of waters bath with thermostatic control and violent stirring condition, in two steps at above-mentioned AlCl ₃Add Na in the aqueous solution ₂CO ₃The aqueous solution; The first step, the interior rate of addition with 800ml/L of preceding 15min adds 70% Na fast ₂CO ₃Solution precipitator; Second goes on foot, and adds the Na of residue 30% in 20min at a slow speed with the 240ml/h rate of addition ₂CO ₃Solution precipitator;

(3) Na ₂CO ₃After the aqueous solution dropwises, sustained reaction 30min under 40 ℃ of condition of water bath heating;

(4) with above-mentioned reaction gained contain the sedimentary mother liquor ageing of white gels shape certain hour after, carry out suction filtration, and adopt deionized water, dehydrated alcohol that throw out is carried out three washings; Place 60 ℃ loft drier dry the precursor that obtains;

(5) with the dry precursor and the fused salt Na of above-mentioned gained ₂CO ₃Part by weight uniform mixing by 1: 6 is placed on this mixture in the vacuum oven then, calcines 1h under 350 ℃ of temperature;

(6) cool to above-mentioned calcined product with the furnace room temperature after, again with absolute ethyl alcohol and deionized water carry out three times the washing, the fused salt that flush away is unnecessary finally obtains nanometer Al after drying ₂O ₃White powder.

Embodiment two: the preparation process of present embodiment is as follows:

(1) with the AlCl of deionized water preparation 0.4mol/L ₃The Na of the aqueous solution and 1mol/L ₂CO ₃The aqueous solution is standby;

(2) with above-mentioned Na ₂CO ₃The aqueous solution is as precipitation agent, under 40 ℃ of waters bath with thermostatic control and violent stirring condition, in two steps at above-mentioned AlCl ₃Add Na in the aqueous solution ₂CO ₃The aqueous solution; The first step, the interior rate of addition with 800ml/L of preceding 15min adds 70% Na fast ₂CO ₃Solution precipitator; Second goes on foot, and adds the Na of residue 30% in 20min at a slow speed with the 240ml/h rate of addition ₂CO ₃Solution precipitator;

(3) Na ₂CO ₃After the aqueous solution dropwises, sustained reaction 30min under 40 ℃ of condition of water bath heating;

(4) with above-mentioned reaction gained contain the sedimentary mother liquor ageing of white gels shape certain hour after, carry out suction filtration, and adopt deionized water, dehydrated alcohol that throw out is carried out three washings; Place 60 ℃ loft drier dry the precursor that obtains;

(5) with dry predecessor and the fused salt KNO of above-mentioned gained ₃Part by weight by 1: 6 evenly mixes, and then this mixture is placed in the vacuum drying oven, calcines 1h under 350 ℃ of temperature;

(6) cool to above-mentioned calcinate with the furnace room temperature after, once more with dehydrated alcohol and deionized water carry out three times the washing, the fused salt that flush away is unnecessary finally obtains nanometer after drying.

Embodiment three: the preparation process of present embodiment and step and the foregoing description 1 are identical.Different is: the fused salt that adopts in the 5th step is LiNO ₃, and predecessor and fused salt LiNO ₃Mix by 1: 6 part by weight, mixture in 350 ℃ of temperature lower calcinations 1 hour, finally makes nanometer Al after washing drying in vacuum drying oven ₂O ₃

Embodiment four: the preparation process of present embodiment and step and the foregoing description 1 are identical.Different is: the fused salt that adopts in the 5th step is LiNO ₃, and predecessor and fused salt LiNO ₃Mix by 1: 12 part by weight, mixture in 550 ℃ of temperature lower calcinations 1 hour, finally makes nanometer Al after washing drying in vacuum drying oven ₂O ₃Instrument test to the foregoing description products therefrom:

(1) the foregoing description 1～4 sample is carried out the XRD test, its test result is seen Fig. 1 and Fig. 2.Be respectively to descend different fused salt NaNO with 550 ℃ among Fig. 1, Fig. 2 at 350 ℃ ₃, KNO ₃, LiNO ₃The XRD figure of auxiliary calcining after product.Behind the dinectly bruning, product all can be demarcated and be Emission in Cubic Al under the different temperatures ₂O ₃Be better than 350 ℃ at 550 ℃ of following product crystalline conditions.Add 6 times of monobasic fused salt results for calcination, the product diffraction maximum can be demarcated and is γ-Al ₂O ₃Add 12 times of monobasic LiNO ₃Fused salt is after 550 ℃ of calcinings, and the diffraction maximum of product is also demarcated and is γ-Al ₂O ₃Explanation is added fused salt and has been caused the product crystalline phase that variation has taken place under uniform temp.

(2) embodiment 1～4 resulting sample is carried out the TEM test, can be learnt by TEM figure, under 350 ℃ of calcination conditions, sample Al ₂O ₃In 100～200nm particle; After adding 6 times of monobasic fused salts, the pattern of sample also has different variations, Al ₂O ₃(add NaNO ₃Fused salt) is flaky crystal state about 20nm; Product A l ₂O ₃(add NiNO ₃Fused salt) occur big laminated structure in, thickness is at 30～40nm.Under 550 ℃ of temperature, add 12 times of NiNO ₃After, product A l ₂O ₃Particle diameter reduces, about about 20nm.

Claims (1)

1. one kind is adopted the auxiliary calcination method of fused salt to prepare nanometer Al ₂O ₃Method, it is characterized in that having following preparation process and step:

A. prepare certain density AlCl with deionized water ₃And Na ₂CO ₃The aqueous solution is standby; AlCl ₃The concentration of the aqueous solution is 0.2～0.6mol/L, Na ₂CO ₃The concentration of the aqueous solution is 0.8～1.2mol/L;

B. under 30～60 ℃ of waters bath with thermostatic control and violent stirring condition, in two steps with different rate of addition at above-mentioned AlCl ₃The Na of adding effect precipitation agent in the water solvent ₂CO ₃The aqueous solution; The first step adds 60～80% precipitation agent Na at 10～20min with the rate of addition of 600～1000ml/h in the time ₂CO ₃Solution; Second step added remaining precipitation agent Na with slow rate of addition 200～300ml/h at 15～25min in the time ₂CO ₃Solution;

C.Na ₂CO ₃After the aqueous solution dropwises, sustained reaction 30～60min under 30～60 ℃ of condition of water bath heating;

D. with above-mentioned reaction gained contain the white gels shape after sedimentary mother liquor ageing for some time, carry out suction filtration, and adopt deionized water, dehydrated alcohol that throw out is repeatedly washed; Place 40～60 ℃ loft drier dry the precursor that obtains;

E. with the dry precursor of above-mentioned gained and fused salt uniform mixing by a certain percentage; Fused salt is any in NaNO3, KNO3, the LiNO3 nitrate; The part by weight of precursor and fused salt is 1: 6～1: 12; The mixture of thing before above-mentioned and fused salt is placed in the vacuum oven, calcines under 350～700 ℃ of temperature, calcination time is 0.5～2.0h;

F. after cooling to above-mentioned calcined product with the furnace room temperature, again repeatedly wash with absolute ethyl alcohol, deionized water, the fused salt that flush away is unnecessary finally obtains nanometer Al after drying ₂O ₃White powder.

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