CN100556817C - Preparation method of porous rutile titanium dioxide - Google Patents

Abstract

A preparation method of porous rutile titanium dioxide, using ilmenite concentrate as raw material, the process steps are as follows: (1) ball milling activation, the ilmenite concentrate is mechanically ball milled and activated in an oxygen-isolated atmosphere; (2) Leaching, volume of sulfuric acid solution: quality of activated ilmenite concentrate=50:1～100:1, heating activated ilmenite concentrate and sulfuric acid solution to 80～130°C for leaching reaction to obtain solid phase porous hydrated titanium dioxide; (3) Solid-liquid separation. After the reaction is completed, the slurry is cooled, and then the solid-liquid separation is carried out by vacuum filtration; (4) The separated porous hydrated titanium dioxide is washed and dried to obtain micropores or micropores and mesopores. Mixed porous rutile titanium dioxide. (5) Calcining the dried porous rutile titanium dioxide mixed with micropores and mesopores at 500-600°C for 2-4 hours to obtain mesoporous rutile titanium dioxide.

Description

Preparation method of porous rutile titanium dioxide

technical field

The invention belongs to a method for preparing porous titanium dioxide, in particular to a method for preparing rutile-type titanium dioxide with a pore size between micropores and mesopores.

Background technique

Substances with a pore size below 2 nm are called microporous compounds or molecular sieves, and substances with a pore size between 2 and 50 nm are called mesoporous materials. Microporous materials (such as natural zeolite) have been widely used in the drying and separation of fluids, the softening of hard water, the treatment of sewage, and the improvement of soil, especially as catalytic materials in petrochemical, fine chemical and daily chemical industries. role. In 1992, Mobil scientists first synthesized the MCM-41 ordered high-silicon mesoporous material, and the mesoporous material also showed excellent catalytic performance in catalytic reactions involving macromolecules, and was used in organic waste degradation and water purification. , automobile exhaust treatment, immobilization and separation of enzymes and proteins, cell/DNA separation, and controlled release of drugs have shown potential application value.

In recent decades, titania has been one of the most widely studied metal oxides as catalysts (especially photocatalysts) and catalyst supports, but most of the developed titania catalytic materials are non-porous structures. Existing studies have shown that porous titanium dioxide with high specific surface area and high crystallinity has better activity, and has been used in the degradation of organic matter (such as CN1287878A, CN1821085A), natural gas and petroleum gas desulfurization (such as CN1712500, CN1508221) and flue gas deNO _X , selective oxidation of o-xylene and other aspects have shown extremely superior catalytic performance.

There have been a lot of researches on the preparation and properties of mesoporous titanium dioxide, but the current preparation methods almost all use organic molecules as templates (such as CN1636879A, CN1821085A), and the removal of templates is either by high-temperature calcination or by organic In the method of solvent extraction, the calcination process easily leads to the collapse of the pore structure and a significant decrease in the specific surface area, while it is difficult to completely remove the template agent through extraction. In addition, titanium dioxide obtained by such methods is usually amorphous and has poor thermal stability.

The patent application with publication number CN1287878A discloses a preparation method without using a template, which uses raw materials such as titanium alkoxide and hexyl orthosilicate to prepare mesoporous _TiO2 materials through a sol-gel process. The disadvantage of this method is that the process steps are complicated, the process parameters are difficult to control, and expensive raw materials such as titanium alkoxide and hexyl orthosilicate need to be used.

The patent application with the publication number CN1807259A discloses a preparation method of mesoporous titanium dioxide. The method adopts a step-by-step hydrolysis method and uses industrial titanium sulfate solution as a raw material to prepare a particle size of 1-2 μm, a pore size of 2-8 nm, and a specific surface area of 150 μm. ~200 m ² /g of mesoporous titanium dioxide.

Contents of the invention

The purpose of the present invention is to provide a new method for preparing porous titanium dioxide. The method not only has simple process and low cost, but also the prepared rutile porous titanium dioxide has pore structure characteristics from micropore to mesopore size.

The preparation method of the porous rutile titanium dioxide of the present invention can not only prepare the rutile titanium dioxide with micropores or micropores and mesoporous mixtures, but also prepare the mesoporous rutile titanium dioxide.

The method for preparing micropores or micropores and mesoporous mixed rutile titanium dioxide according to the present invention uses ilmenite concentrate as raw material, and the process steps are as follows:

(1) ball mill activation

In an oxygen-isolated atmosphere (such as nitrogen atmosphere or vacuum), the ilmenite concentrate is mechanically milled with a ball mill to activate the ilmenite concentrate.

(2) Leaching

The activated ilmenite concentrate is measured in grams or kilograms, the sulfuric acid solution with a mass concentration of 5-20% is measured in milliliters or liters, the volume of sulfuric acid solution: the quality of the activated ilmenite concentrate (referred to as liquid-solid ratio)=50:1-100 : 1.

The activated ilmenite concentrate measured according to the above-mentioned liquid-solid ratio and sulfuric acid solution are heated to 80-130° C. for leaching reaction, and the reaction time is 2-4 hours to obtain a solid phase—porous hydrated titanium dioxide.

(3) Solid-liquid separation

After the reaction is completed, the slurry is cooled to 30-50° C., and then the porous hydrated titanium dioxide is separated from the mother liquor by vacuum filtration.

(4) washing and drying

After the separated hydrated titanium dioxide is washed and dried, micropores or micropores and mesoporous mixed rutile titanium dioxide are obtained.

The method for preparing mesoporous rutile titanium dioxide according to the present invention is to add a calcining step on the basis of the above method, that is, the dried rutile titanium dioxide mixed with micropores and mesoporous pores is calcined at 500-600°C for 2-4 hours to obtain Mesoporous rutile titanium dioxide.

In the above method, the ball mill used for ball mill activation can be a planetary ball mill or a vibration ball mill, but the balls and the grinding cylinder of the ball mill are preferably made of stainless steel. If the ball mill is a planetary ball mill, the preferred activation conditions are: the ball-to-material ratio (mass ratio of grinding balls to ilmenite concentrate) during ball milling is 20:1 to 40:1, and the centrifugal acceleration of the grinding balls is at least 180m/ ^s , The ball milling time is 2 to 6 hours. If the ball mill is a vibrating ball mill, the preferred activation conditions are: the ball-to-material ratio (mass ratio of the ball to the ilmenite concentrate) during ball milling is 40:1 to 60:1, and the centrifugal acceleration of the ball is at least ^98m /s , The ball milling time is 2 to 6 hours.

The present invention has the following beneficial effects:

1. The method of the present invention does not require a template agent, and only uses natural ilmenite as a titanium source. Porous titanium dioxide can be prepared through simple mechanical ball milling activation and sulfuric acid leaching, so the raw materials are easy to obtain, the process is simple, and the cost is low.

2. The method of the present invention can obtain titanium dioxide with micropores, mesopores or a mix of micropores and mesopores (see examples), so it has a wide range of applications.

3. The products prepared by the method of the present invention have relatively high crystallinity, are all rutile type, have large specific surface area and high thermal stability.

Description of drawings

Fig. 1 is the X-ray diffraction spectrum figure of the ilmenite used by the method of the present invention and the porous rutile type titanium dioxide prepared, wherein, Fig. 1A is the X-ray diffraction spectrum figure of the ilmenite concentrate without ball milling activation, Fig. 1B is the X-ray diffraction spectrum of ilmenite concentrate activated by ball milling, Figure 1C is the X-ray diffraction spectrum of uncalcined porous rutile titanium dioxide, and Figure 1D is the mesoporous rutile titanium dioxide calcined at 500 °C Figure 1E is the X-ray diffraction spectrum of mesoporous rutile titanium dioxide obtained by calcination at 600°C.

Fig. 2 is the pore size distribution curve of uncalcined porous rutile titanium dioxide obtained by leaching in sulfuric acid solutions with different concentrations.

Fig. 3 is the pore size distribution curve of the hydrated titanium dioxide obtained by leaching in a sulfuric acid solution with a mass concentration of 10% and the mesoporous rutile titanium dioxide obtained after calcining at different temperatures.

Fig. 4 is a photo of the morphology of hydrated titanium dioxide obtained by leaching in a sulfuric acid solution with a mass concentration of 10%, wherein Fig. 4A is a scanning electron micrograph, and Fig. 4B is a high-resolution transmission electron micrograph.

Detailed ways

The ball mill, leaching kettle, vacuum filter, drying and calcination equipment involved in the following examples are all general-purpose equipment and commercially available. The chemical composition (mass percentage) of the raw material ilmenite concentrate used in the following examples is: FeO 34.21%; TiO ₂ 47.25%; Fe ₂ O ₃ 5.56%; MgO 6.23%; SiO ₂ 2.75%; Al ₂ O ₃ 1.49% %; MnO ₂ 0.61%.

In the following examples, the _N2 adsorption-desorption curve of the sample was measured using the Nova1000e specific surface meter of Quantachrome Corporation of the United States. The specific surface area of the sample was calculated using the BJH method and the desorption branch to calculate the mesopore size distribution, and the HK mode was used to calculate the micropore size distribution; the phase composition of the sample was determined by the Philips X'pertpro MPD X-ray diffractometer; the Hitachi S -450 scanning electron microscope combined with X-ray energy spectrometer to determine the content of sulfuric acid and iron in the sample; JEOL JSM-5900LV scanning electron microscope (SEM) and FEI Tecnai F20 high-resolution transmission electron microscope (HR-TEM) were used to analyze the obtained titanium dioxide appearance to observe.

Examples 1-8

The processing steps of each embodiment are as follows in sequence:

(1) ball mill activation

Under vacuum (vacuum degree is -0.085MPa) or nitrogen atmosphere, use stainless steel as the ball and cylinder material of the ball mill, and perform ball milling activation according to the ball milling conditions in Table 1.

(2) Leaching

Dosing and leaching reaction according to the leaching conditions in Table 1; during this process, the dissolved titanium is hydrolyzed to obtain a hydrated titanium dioxide solid phase that has adsorbed a small amount of ferric sulfate and sulfuric acid, and most of the dissolved iron and other impurities remain in the mother liquor .

(3) Solid-liquid separation

After the reaction is completed, cool the slurry to any temperature between 30°C and 50°C, and then use a vacuum filter to separate the solid and liquid under the condition of a vacuum of -0.06MPa.

(4) washing and drying

The separated porous hydrated titanium dioxide is successively washed with a mass concentration of 3% sulfuric acid solution, a mass concentration of 1% sulfuric acid solution and distilled water at room temperature, adding 200ml of washing liquid each time, and the washing time is 20min. Suction filtration separation under the condition of -0.06MPa.

The washed hydrated titanium dioxide was placed in an oven and dried under normal pressure at 100°C for 3 hours to obtain microporous or mixed microporous and mesoporous titanium dioxide. The specific surface area and pore structure characteristics are shown in Table 1.

Table 1 Preparation conditions and physical and chemical properties of microporous or microporous and mesoporous titanium dioxide mixed

Example Milling conditions Leaching conditions Specific surface area (m²/g) Pore structure characteristics 1 Planetary ball mill (ball milling under vacuum) ball centrifugal acceleration 180m/s² ball-to-material ratio 40:1 ball milling time 4h Sulfuric acid solution concentration 10% liquid-solid ratio 100:1 leaching reaction at normal pressure, 100 ℃, leaching time 4h 257.6 microporous, mesoporous 2 Planetary ball mill (ball mill under nitrogen atmosphere) The concentration of sulfuric acid solution is 5%, 284.8 microporous,

The centrifugal acceleration of the grinding ball is 210m/s²The ball-to-material ratio is 20:1 The ball milling time is 6h The liquid-solid ratio is 100:1, the leaching reaction is at normal pressure and 80°C, and the leaching time is 4h Mesopores 3 Planetary ball mill (ball mill under vacuum) ball centrifugal acceleration 180m/s² ball-to-material ratio 40:1 ball milling time 3h The concentration of sulfuric acid solution is 15%, the liquid-solid ratio is 50:1, the leaching reaction is carried out under normal pressure and 110°C, and the leaching time is 2h 109.3 microporous 4 Planetary ball mill (ball milling under nitrogen atmosphere) ball centrifugal acceleration 210m/s² ball-to-material ratio 30:1 ball milling time 2h Sulfuric acid solution concentration 20%, liquid-solid ratio 50:1, leaching reaction at 2 atmospheric pressure, 130°C, leaching time 2h 106.5 microporous 5 Vibrating ball mill (ball milling under nitrogen atmosphere) ball centrifugal acceleration 98m/s² ball-to-material ratio 60:1 ball milling time 6h Sulfuric acid solution concentration 10%, liquid-solid ratio 100:1, leaching reaction at 3 atmospheres, 130°C, leaching time 4h 262.1 microporous, mesoporous 6 Vibrating ball mill (ball milling under vacuum) ball centrifugal acceleration 147m/s² ball material ratio 50:1 ball milling time 4h The concentration of sulfuric acid solution is 5%, the liquid-solid ratio is 100:1, the leaching reaction is at normal pressure and 100°C, and the leaching time is 4h 275.6 microporous, mesoporous 7 Vibrating ball mill (ball milling under nitrogen atmosphere) ball centrifugal acceleration 196m/s² ball material ratio 40:1 ball milling time 2h The concentration of sulfuric acid solution is 15%, the liquid-solid ratio is 50:1, the leaching reaction is carried out under normal pressure and 110°C, and the leaching time is 2h 96.3 microporous 8 Vibrating ball mill (ball milling under vacuum) ball centrifugal acceleration 147m/s² ball material ratio 40:1 ball milling time 6h The concentration of sulfuric acid solution is 20%, the liquid-solid ratio is 50:1, the leaching reaction is carried out at normal pressure and 80°C, and the leaching time is 2h 102.3 microporous

^* Note: 1) The X-ray diffraction spectrum of the ilmenite concentrate that has not been activated by ball milling used in each embodiment is shown in Figure 1A;

2) In the above examples, the typical X-ray diffraction spectrum of the ilmenite concentrate after ball milling activation is shown in Figure 1B;

3) In the above examples, the typical X-ray diffraction spectrum of uncalcined porous rutile titanium dioxide is shown in Figure 1C;

4) The average pore diameter of micropores is 0.8-1.0nm, and the average pore diameter of mesopores is 3.4-3.7nm;

5) The porous titanium dioxide obtained under all conditions is rutile type;

6) The morphology of the hydrated titanium dioxide prepared in Example 1 is shown in FIG. 4 .

Examples 9-12

The processing steps of each embodiment are as follows in sequence:

(1) ball mill activation

Under vacuum (vacuum degree is -0.085MPa) or nitrogen atmosphere, use stainless steel as the ball and cylinder material of the ball mill, and perform ball milling activation according to the ball milling conditions in Table 2.

(2) Leaching

Carry out ingredients and leaching reaction according to the leaching conditions in Table 2; during this process, the dissolved titanium is hydrolyzed to obtain a hydrated titanium dioxide solid phase that has adsorbed a small amount of ferric sulfate and sulfuric acid, and most of the dissolved iron and other impurities remain in the mother liquor .

(3) Solid-liquid separation

After the reaction is completed, cool the slurry to any temperature between 30°C and 50°C, and then use a vacuum filter to separate the solid and liquid under the condition of a vacuum of -0.06MPa.

(4) washing and drying

The separated porous hydrated titanium dioxide is successively washed with a mass concentration of 3% sulfuric acid solution, a mass concentration of 1% sulfuric acid solution, and distilled water at room temperature, adding 200ml of washing liquid each time, and the washing time is 20min. Suction filtration separation under the condition of -0.06MPa.

The washed hydrated titanium dioxide was placed in an oven and dried under normal pressure at 100° C. for 3 hours to obtain a mixed microporous and mesoporous titanium dioxide. The specific surface area and pore structure characteristics are shown in the corresponding examples in Table 1.

(5) Calcination

The dried microporous and mesoporous mixed titanium dioxide was placed in a muffle furnace and calcined according to the conditions described in Table 2 to obtain mesoporous rutile titanium dioxide.

Table 2 Preparation conditions and physical and chemical properties of mesoporous rutile titanium dioxide

Example Ball milling and leaching conditions Calcination conditions Specific surface area (m²/g) Pore structure characteristics Average Mesopore Diameter (nm) 9 Same as Example 2, see Table 1 Calcination temperature 500°C Calcination time 4h 172.3 Mesopores 5.3 10 Same as Example 2, see Table 1 Calcination temperature 600°C Calcination time 2h 98.5 Mesopores 9.2 11 With embodiment 5, see table 1 Calcination temperature 500°C Calcination time 3h 153.7 Mesopores 5.1 12 With embodiment 6, see table 1 Calcination temperature 600°C Calcination time 2h 89.6 Mesopores 9.4

^* Note: 1) Titanium dioxide obtained under all conditions is rutile type;

2) In the above examples, the typical X-ray diffraction spectrum of mesoporous rutile titanium dioxide obtained by calcination at 500°C is shown in Figure 1D, and the typical X-ray diffraction spectrum of mesoporous rutile titanium dioxide obtained by calcination at 600°C is shown in Figure 1E .

Claims (5)

1, a kind of preparation method of porous rutile type titanium dioxide, it is characterized in that be raw material with ilmenite concentrate, process step is as follows successively: (1) ball mill activation In the atmosphere of isolating oxygen, the ilmenite concentrate is mechanically milled with a ball mill to activate the ilmenite concentrate; (2) Leaching The activated ilmenite concentrate is measured in kilograms, the sulfuric acid solution with a mass concentration of 5-20% is measured in liters, the sulfuric acid solution volume: the activated ilmenite concentrate quality=50:1～100:1; The activated ilmenite concentrate and sulfuric acid solution measured according to the above liquid-solid ratio are heated to 80-130°C for leaching reaction, and the reaction time is 2-4 hours to obtain a solid phase - porous hydrated titanium dioxide; (3) Solid-liquid separation After the reaction is completed, the slurry is cooled to 30-50°C, and then the porous hydrated titanium dioxide is separated from the mother liquor by vacuum filtration; (4) washing and drying The separated porous hydrated titanium dioxide is washed and dried to obtain porous rutile titanium dioxide with micropores or micropores and mesopores mixed. 2. The preparation method of porous rutile-type titanium dioxide according to claim 1, characterized in that it also includes calcination, that is, the dried porous rutile-type titanium dioxide mixed with micropores and mesopores is calcined at 500-600°C for 2-4 hours, Mesoporous rutile titanium dioxide was obtained. 3. The method for preparing porous rutile titanium dioxide according to claim 1 or 2, characterized in that the balls and cylinders of the ball mill used in the ball mill activation step are made of stainless steel. 4. The method for preparing porous rutile titanium dioxide according to claim 3, characterized in that the ball mill used in the ball mill activation step is a planetary ball mill, the ball-to-material ratio during ball milling is 20:1 to 40:1, and the centrifugal acceleration of the balls is at least It is 180m/s ² , and the ball milling time is 2 to 6 hours. 5. The method for preparing porous rutile titanium dioxide according to claim 3, characterized in that the ball mill used in the ball milling activation step is a vibrating ball mill, the ball-to-material ratio during ball milling is 40:1 to 60:1, and the centrifugal acceleration of the balls is at least It is 98m/s ² , and the ball milling time is 2 to 6 hours.

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