CN1076319C - Method for preparing nanometre-grade titanium dioxide - Google Patents

Abstract

The present invention discloses a novel method for preparing nanometer titanium dioxide, particularly a novel method using a homogeneous precipitation method to prepare nanometer titanium dioxide. The present invention is characterized in that H2TiO3 is used as a raw material; urea is used as a uniform precipitating agent; the concentration of reactant is 1.44*10<-3>g/l; the ratio of the amount of substance of the urea to TiOSO4 is from 1: 1 to 5: 1; the temperature of the hydrolysis reaction of the urea is from 95 to 110 DEG C; the reaction time is from 2.0 to 4.0 hr; and TiO (OH) 2 as synthesized intermediate sedimentation is calcined for 2.5 to 3.5 hr under 800 to 1000 DEG C to obtain the nanometer TiO2. The method has the advantages of simple production process, convenient industrialization production and broad application prospect.

Description

Method for preparing nano-scale titanium dioxide

The invention discloses a method for preparing nano-titanium dioxide, in particular to a method for preparing nano-titanium dioxide by using a uniform precipitation method.

Nano TiO 2₂Is an important inorganic functional material with the size about that of common TiO₂About 1/10, the particle size is usually 1 to 100 nm. The particle size is miniaturized, so that the nano TiO₂The surface effect, small-size effect, quantum effect and macroscopic quantum tunneling effect which are not possessed by the bulk material are generated, so that the material has the advantages of good weather resistance, chemical corrosion resistance, strong ultraviolet resistance, excellent transparency, uniform particle size distribution, good dispersibility and the like. Nano TiO 2₂Besides the basic properties of the nano material, the nano material also has the relative stability of physical properties and chemical properties, nontoxicity, non-migration, photoconductivity, photocatalysis and color effect, has transparency and ultraviolet scattering capability, and can be used for automobile finish, photosensitive materials, photocatalysts, cosmetics, food packaging materials, ceramic additives, gas sensors, temperature sensors, magnetic recording materials and the like. Domestic and overseas synthesis of nano TiO₂The methods of (1) mainly include a sol-gel method (S-G method), a vapor phase method (CVD method) and a peptization method. S-G method using hydrolysis and polycondensation of metal alkoxide as an effective method for preparing nano-powder, TiO with good uniformity has been synthesized₂Gel and nano TiO₂Particles, but this method is costly. The CVD method has high requirements on technology and material, complex process and large investment. In comparison, the peptization method has much simpler process, but has the defect that the raw material is reagent-grade TiOSO₄Or Ti (SO)₄)₂The source is less and the price is not very expensive.

The invention aims to provide a method which has low production cost and simple production process and is convenient for industrialized production of nano-scale so as to overcome the defects of the prior art.

The invention is realized as follows: the following details the use ofPreparation of nano-grade TiO by homogeneous precipitation method₂The production process of (1).

1. The preparation principle is as follows:

the homogeneous precipitation method is a method in which a precipitant added to a solution does not react with a component to be precipitated immediately but is slowly generated in the whole solution by a chemical reaction, so that a crystal-forming ion in the solution is slowly and uniformly released from the solution by the chemical reaction. Therefore, as long as the speed of generating the precipitant is controlled, the phenomenon of uneven concentration can be avoided, and the supersaturation degree is controlled within a proper range, so that the growth speed of the particles is controlled, and the nano-scale particles with uniform and compact particle size, convenient washing and high purity are obtained.

With H₂TiO₃Preparing nano TiO by using urea as uniform precipitant₂The reaction equation of (a) is as follows:

2. the preparation conditions are as follows:

the invention adopts urea as a precipitator, the hydrolysis speed of the urea is the key for determining the grain diameter of ultrafine grains and the product yield, the temperature is higher than 130 ℃, the urea can generate isomerization condensation, and the optimal reaction temperature is 95-110 ℃. Since the urea hydrolysis rate increases with increasing residence time, a certain reaction time, preferably 2.5-4.0hr, when TiOSO is used, must be maintained to obtain a high product yield₄At a constant concentration, urea/TiOSO₄The larger the ratio (amount of substance) is, the OH in the solution^-The larger the concentration, the larger the supersaturation, and the more favorable the formation of a precipitate having a small particle size. At the same time, the excessive urea can ensure TiOSO in a certain time₄And (4) fully reacting. Urea and TiOSO₄The optimal material quantity ratio is 1: 1-51. In dilute TiOSO₄At the concentration, the urea hydrolysis rate is high, but the crystallization product is easy to grow into small and large crystal grains. Therefore, the concentration of the solution should not be too low or too high. TiOSO₄The optimal concentration is 1.44 × 10-³g/l. Calcining at 800-850 ℃ to obtain anatase TiO₂Calcining at 850-950 ℃ to obtain mixed crystal TiO₂Calcining at 950-1000 deg.C to obtain rutile-type TiO₂. The calcination time is preferably 2.5 to 4.0 hr. The invention has the advantages that: nano TiO prepared by uniform precipitation method₂Uniform granularity, good dispersity and greatly reduced nano TiO₂The cost (about 1/3-1/4 of the cost of the S-G method and the CVD method) is reduced, and the production process is simpler and is convenient for industrial production.

Two embodiments of the invention:

1. according to the ratio of urea to H₂TiO₃The two raw materials are respectively weighed according to the mass ratio of 5: 1, and are added into the mixture H₂TiO₃Adding H₂SO₄Heating the solution to complete the reaction, adding urea to the solutionAdding distilled water to make TiOSO₄The concentration is 1.44X 10^-3g/l, reaction at 95 ℃ for 3hr to obtain TiO (OH)₂Precipitating, filtering, washing, drying, calcining at 800 deg.C for 2.5hr to obtain nanometer TiO₂The yield was 80.36%, and the average particle diameter was 30 nm.

2. According to the ratio of urea to H₂TiO₃The two raw materials are respectively weighed according to the mass ratio of 5: 1, and are added into the mixture H₂TiO₃Adding H₂SO₄Heating the solution to complete the reaction, adding urea into the solution, and adding distilled water to make TiOSO₄The concentration is 1.44X 10^-3g/1, reaction at 95 ℃ for 3hr to obtain TiO (OH)₂Precipitating, filtering, washing, drying, calcining at 950 deg.C for 3hr to obtain nanometer TiO₂The yield was 91.40%, and the average particle diameter was 45 nm.

Claims (2)

1. A kind ofThe method for preparing the nano titanium dioxide by using the uniform precipitation method is characterized by comprising thefollowing steps: with H₂TiO₃And H₂SO₄TiOSO produced by the reaction₄As raw material, urea as homogeneous precipitant, wherein TiOSO is controlled₄The concentration is 1.44X 10^-3g/l, amount of urea and TiOSO₄The mass ratio of the components is 1: 1-5: 1, the reaction temperature is 95-110 ℃, the reaction time is 2.5-4.0hr, and TiO (OH) is generated₂(ii) a And the intermediate precipitate TiO (OH) synthesized₂Calcining at 800-1000 deg.C for 2.5-3.5hr to obtain nanometer TiO₂。

2. The method for producing nano-sized titanium dioxide according to claim 1, wherein: calcining at 800-850 ℃ to obtain anatase TiO₂Calcining at 850-950 ℃ to obtain mixed crystal TiO₂Calcining at 950-1000 deg.C to obtain rutile-type TiO₂。