CN1192992A

CN1192992A - Method for preparing nanometre-grade titanium dioxide

Info

Publication number: CN1192992A
Application number: CN97108439A
Authority: CN
Inventors: 祖庸; 李晓娥; 任莉; 卫志贤; 张秀成; 雷闫盈
Original assignee: Northwest University
Current assignee: Northwest University
Priority date: 1997-03-06
Filing date: 1997-03-06
Publication date: 1998-09-16
Anticipated expiration: 2017-03-06
Also published as: CN1076319C

Abstract

The new method for preparing nanometer-grade TiO2 by using homogeneous precipitation process is characterized by that using H2TiO3 as raw material, using urea as homogeneous precipitant, concentration of reactant is 1.44X10 to the power -3 g/l, weight ratio of urea material and TiOSO4 material is 1 : 1--5 : 1, reaction temperature of urea hydrolysis is 95-110 deg.C, reaction time is 2.0-4.0 hr, and roasting the synthetic intermediate deposit matter TiO(OH)2 for 2.5-3.5 hr at 800-1000 deg.C to obtain nanometer-grade TiO2. Said invented is simple in production process, and favourable for industrial production.

Description

Novel method for preparing nano-scale titanium dioxide

The invention discloses a method for preparing nano-titanium dioxide, in particular to a novel 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 minimized, 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 generatedTherefore, the coating 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 (2) 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 for producing nano TiO, which has low production cost and simple production process and is convenient for industrialized production₂To overcome the deficiencies of the prior art.

The invention is realized as follows: the following details the preparation of nano-sized TiO by homogeneous precipitation method in conjunction with the preparation principle and preparation conditions₂The 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 a 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 must be maintained to obtain a high product yield. The optimal reaction time is 2.5-4.0 hr. When TiOSO₄At 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 amount ratio is 1: 1-5: 1. 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 metatitanic acid at 800-850 ℃ to obtain anatase TiO₂(ii) a Calcining at 850-950 ℃ to obtain mixed crystal TiO₂(ii) a Calcining at 950 ℃ and 1000 ℃ to obtain rutile TiO₂. The calcination time is preferably 2.5-3.5 hr. The invention has the advantages that: nano TiO prepared by uniform precipitation method₂Uniform granularity, good dispersity and greatly reduced nano TiO₂The cost of the S-G method and the CVD method is about 1/3-1/4, and the production process is simplerAnd the method 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 into the solution, and adding 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 TiOSO₄Concentration of 1.4410^-3g/l, 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

1. A new method for preparing nano-scale titanium dioxide by a uniform precipitation method is characterized in that: with H₂TiO₃The raw material is urea as homogeneous precipitant, and the reactant concentration is 1.44X 10^-3g/l, amount of urea substance and TiOSO₄The mass ratio of substances is 1: 1-5: 1, the reaction temperature of urea hydrolysis is 95-110 deg.C, and the reaction time is 2.5-4.0 hr; and the intermediate precipitate TiO (OH) synthesized₂Calcining at 800-₂(800-₂Calcining at 850-950 ℃ to obtain a mixed crystal form, and calcining at 950-1000 ℃ to obtain rutile TiO₂)。