CN1325157C - Method for preparing large aperture aluminium hydroxide contained titanium and silicon - Google Patents

Abstract

The invention discloses an aluminum hydroxide with a large aperture containing titanium and silicon composite additives and a preparation method thereof. The present invention uses ultrasonic waves when introducing titanium and silicon into aluminum hydroxide, which not only ensures the uniform dispersion of titanium and silicon on the surface of aluminum hydroxide, but also makes the aluminum hydroxide particles containing titanium and silicon finer, with higher pore volume and specific surface area. The larger the size, the larger the average pore size. When the aluminum hydroxide containing titanium and silicon of the invention is used as a catalyst carrier and a hydrogenation catalyst, it has good physical and chemical indicators and performance.

Description

A kind of preparation method of titanium and silicon aluminum hydroxide with large aperture

technical field

The present invention relates to an aluminum hydroxide containing titanium and silicon composite additives with large pores and a preparation method thereof, in particular to a product with titanium and silicon evenly distributed on the surface of aluminum hydroxide and having larger pore volume and specific surface area after roasting Aluminum hydroxide containing titanium and silicon with average pore size and a preparation method thereof.

Background technique

In recent years, the hydrotreating process of residual oil has been paid attention to by people. With the need for deep processing of residual oil and the higher and higher requirements for environmental protection, more extensive and in-depth research must be carried out on catalysts for residual oil hydrotreating in order to continuously develop new catalysts to meet actual needs. Therefore, it is a great challenge for researchers to develop more active and selective residue hydrotreating catalysts. The means to develop catalysts with higher activity and selectivity is usually to develop new catalyst support materials and select noble metal catalyst components. Introducing various additives to aluminum hydroxide in the development of new materials has always been the direction of people's continuous research. The purpose of introducing one or more elements such as Si, P, Ti, B, Mg, F, etc. is basically the same, that is, to adjust the acidity of the catalyst and/or improve the interaction between the active component and the support. However, adding one or more additives during the catalyst preparation process will complicate the catalyst preparation process, or cause problems such as difficulty in forming the catalyst; adding the additives required for the preparation of the catalyst during the production of the carrier raw material can make the catalyst preparation The process is simple, and at the same time, it will more effectively adjust the acidity, pore properties and other physical and chemical properties of the support, thereby more effectively adjusting the acidity of the catalyst and/or improving the interaction between the active component and the support, and will also reduce the environment during catalyst preparation. pollution problem.

There are many methods for preparing large-pore carriers, such as CN1087289A, which discloses a preparation method of a macroporous γ-Al ₂ O ₃ carrier, which is to roast the carrier precursor at high temperature; CN1160602A is obtained by adding physical and chemical pore-enlarging agents, and then calcining at high temperature; EP0097740 uses a hydrothermal treatment method to expand the holes. Their disadvantages are that they do not contain corresponding additives, have weak acidity, and the physical and chemical properties of the carrier have not been effectively improved.

EP0339640 discloses a method for preparing titanium-containing alumina by co-precipitation, which can prepare well-dispersed titanium-containing aluminum hydroxide, but the co-precipitation method has the problem of bulk phase retention, so that the promotion effect of TiO2 on catalyst performance cannot be fully exerted. In addition, the co-precipitation method is the simultaneous precipitation of two substances, so the precipitation conditions must be coordinated so that the two substances can reach a certain precipitation rate, and at the same time, the two precipitates must achieve certain physical and chemical properties to meet the use requirements. However, the same precipitation conditions cannot be the best precipitation conditions for two substances at the same time. Especially for alumina, its physical and chemical indicators are often adjusted according to the requirements of use. One of the main adjustment methods is to change the precipitation conditions, and the other It is impossible for a substance to always satisfy its own precipitation conditions while adapting to the different precipitation conditions of the previous substance. Simply put, the co-precipitation conditions are sometimes not the optimal precipitation conditions for the two substances, thus causing the inflexibility of the co-precipitation method, and thus the application is limited. It is more difficult to prepare aluminum hydroxide containing two or more additives by this method; the preparation process uses a soluble titanium salt solution, which is costly and produces acid mist during the preparation process, which pollutes the environment and corrodes equipment.

CN1289636A discloses a method for preparing titanium-containing aluminum hydroxide by precipitating titanium salt in aluminum hydroxide slurry, which can prepare well-dispersed titanium-containing aluminum hydroxide, but because the titanium salt solution contains Cl- ^and SO ₄ ² -plasma , corrode equipment, and when aluminum hydroxide is roasted into γ-Al ₂ O ₃ , gases such as chlorine and sulfur dioxide will be produced to pollute the environment; The method of titanium, silicon aluminum hydroxide, although reduced environmental pollution, because adding solid particle (although its particle size is to less than 65 μ m) can produce aggregate when sodium metaaluminate solution and carbon dioxide react to gel, influence the production of aluminum hydroxide Particle size, and the distribution of titanium and silicon in aluminum hydroxide will not be uniform, which will lead to a decrease in its performance.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a titanium and silicon-containing aluminum hydroxide and its products which are uniformly distributed on the surface of aluminum hydroxide and have larger pore volume, specific surface area and larger average pore diameter after firing. Preparation.

The roasted aluminum hydroxide containing titanium and silicon of the present invention contains 1-20w% of titanium dioxide, preferably 5-15w%, contains 1-20w% of silicon dioxide, preferably 2-15w%, and has a pore volume of 0.9-1.2ml /g, the specific surface is 360-450m ² /g, the average pore diameter is 10-15nm, the dispersion degree I _Ti /I _Al of titanium on alumina is more than 0.3, generally 0.3-0.4, the dispersion of silicon on alumina The degree I _Si /I _Al is 0.2 or more, generally 0.2 to 0.3.

The preparation process of the aluminum hydroxide containing titanium and silicon of the present invention is as follows:

The sodium metaaluminate solution, titanium-containing compound slurry, silicon-containing compound solution and carbon dioxide gas are reacted to form a gel under stirring conditions, filtered and dried to obtain the aluminum hydroxide product containing titanium and silicon of the present invention. Aluminum hydroxide of silicon has the characteristics of uniform distribution of titanium and silicon, average pore size, specific surface area and large pore volume after roasting. The gelling process is carried out under the action of ultrasonic waves. The frequency of the ultrasound is 10-180 kHz, preferably 20-100 kHz, and the power of the ultrasound is 0.01-20 W/mL, preferably 0.05-10 W/mL based on the volume of the gelled material.

In the process of preparing aluminum hydroxide containing titanium and silicon in the present invention, ultrasonic waves are used to introduce low-cost titanium and silicon compounds in the process of preparing aluminum hydroxide. There is no discharge of pollutants during the preparation process, and there is no environmental pollution; at the same time, when the ultrasonic wave propagates in the medium, due to the energy concentration, the action of the sound wave and the medium can cause many physical changes in the medium. For example, the sawtooth wave effect due to the nonlinearity of ultrasonic vibration has a crushing effect, which can make the particles of aluminum hydroxide colloid and titanium-containing compounds finer, and the titanium in the prepared aluminum hydroxide containing titanium and silicon and silicon are more evenly distributed on the surface of aluminum hydroxide. In addition, due to the effect of ultrasonic waves, the size, shape and accumulation mode of primary particles in the process of aluminum hydroxide gelling reaction are changed, so that the final product has larger pore volume, specific surface area and average pore diameter, and its properties are more uniform. Since titanium and silicon are evenly distributed on the surface of aluminum hydroxide, and the carrier has high acidity and average pore size, the preparation of hydroconversion and/or hydrodenitrogenation and carbon removal catalysts using this raw material as a carrier will greatly weaken the The competition between titanium, silicon and active metals is eliminated, and the utilization rate of active metals is improved, so that the catalyst activity is higher.

Detailed ways

The materials and operating conditions used in the specific preparation process of the aluminum hydroxide containing titanium and silicon of the present invention can be the same as the prior art, the main difference is that the colloidal process is carried out under the action of ultrasonic waves, and the specific steps include:

(1) Prepare sodium metaaluminate solution, titanium-containing compound slurry, and silicon-containing compound solution;

(2) React sodium metaaluminate solution, titanium-containing compound slurry, silicon-containing compound solution and carbon dioxide gas under stirring conditions to form a gel, and after mixing the raw material solution or slurry, pass into carbon dioxide gas to form a gel or one or two of them Or three kinds of gelling are added continuously while carbon dioxide gas is introduced. After the gelation is completed, the ultrasonic transducer is closed and the introduction of carbon dioxide gas is stopped. The gelling process is carried out under the action of ultrasonic waves;

(3) Filtrating the liquid-solid mixture obtained in step (2), washing and drying the filter cake.

The concentration of the above sodium metaaluminate solution is 5-60g Al ₂ O ₃ /l. The above-mentioned titanium-containing compound slurry is made of titanium-containing compounds such as metatitanic acid and titanium dioxide, which are ground into a slurry with a particle size of less than 65 μm by adding water, and then diluted with water to 5-40gTiO ₂ /l, and its pH value is adjusted to 7-11, preferably It is 7-8, and it is carried out under the condition of stirring, and its pH value is suitably adjusted with ammonia water, and the concentration of ammonia water is preferably 0.1-20w%. The addition amount of the titanium-containing compound slurry is based on the final product, wherein the titanium dioxide content is 0.1-20w%, preferably 4-15w%. The above-mentioned silicon-containing compound solution is a sodium silicate solution or a silica sol solution, and the concentration is 5-40 gSiO ₂ /l. The added amount of the silicon-containing compound solution is based on the final product, wherein the silicon dioxide is 1-20w%, preferably 2-15w%. The gel forming temperature is controlled at 10-45°C according to the required pore properties of the aluminum hydroxide containing titanium and silicon, and the concentration of carbon dioxide is controlled at 10-50v%. When the pH value of the glue-forming liquid is controlled to be 9-12, carbon dioxide is stopped. It can be aged or not, and the aging time should not exceed 2 hours at most. The filter cake obtained after filtering the slurry is washed with deionized water for 1 to 5 times until the prepared aluminum hydroxide contains <0.05% by weight of Na ⁺ , and then dried at a temperature of 80 to 180°C for 2 to 12 hours.

The ways of adding various raw material solutions and slurries can be selected according to the needs. For example, the following ways can be used: (1) Pass carbon dioxide gas into the sodium metaaluminate solution, and at the same time add titanium-containing compound slurry and/or silicon-containing compound at a certain flow rate solution; (2) After mixing sodium metaaluminate solution with titanium-containing compound slurry and/or silicon-containing compound solution, carbon dioxide gas is passed into gel; (3) carbon dioxide gas is passed into titanium-containing compound slurry and/or silicon-containing compound solution Compound solution, while continuously adding sodium metaaluminate solution.

The aluminum hydroxide containing titanium and silicon prepared by the method of the present invention is used as a raw material, and undergoes a molding-roasting-impregnation-roasting process, or a kneading-shaping-calcination process, or a kneading-shaping-roasting-impregnation-roasting process by a conventional method. Process to make hydrogenation catalyst, especially suitable for residual oil hydrogenation treatment. The firing conditions are usually in an air atmosphere at 350-800°C for 1-10 hours.

Further describe technical characterictic of the present invention by comparative example and embodiment below, but not limited to embodiment.

Example 1

Put 500mL of sodium metaaluminate solution with a concentration of 30gAl ₂ O ₃ /l in the ultrasonic transducer, control the transmitting power of the ultrasonic transducer to 200W, the frequency is 25kHz, the temperature is 15°C, and carbon dioxide gas with a concentration of 40v% is introduced , adding the concentration of slurry under constant stirring is 20gTiO ₂ /l metatitanic acid slurry (pH value is 8.0, particle size is less than 40 μ m), so that the carrier contains TiO ₂ is 10% by weight; adding concentration is 20SiO ₂ / 1 sodium silicate solution, so that the carrier contains 8.0% by weight of silicon dioxide. Continue to feed carbon dioxide gas until the pH value of the slurry is 10, stop passing carbon dioxide gas, age the slurry for 1.0 hour, and turn off the ultrasonic transducer. Then filter and wash with deionized water until the carrier contains Na ⁺ <0.05w% by weight, dry (120° C.) for 4 hours, and then crush to 180 mesh to obtain product A of the present invention.

Example 2

Compared with Example 1, the transmitting power of the ultrasonic transducer is changed to 50W and the frequency is 25kHz, and the amount of other materials and operating conditions are the same as in Example 1, that is, Product B of this example.

Example 3

Compared with Example 1, the transmitting power of the ultrasonic transducer is changed to 800W and the frequency is 50kHz, and the amount of other materials and operating conditions are the same as in Example 1, namely Product C of this example.

Example 4

Compared with Example 1, the _TiO2 content in the carrier is increased to 15%, and the amount of other materials and operating conditions are the same as in Example 1, that is, the product D of this cost example.

Example 5

Compared with Example 1, increase the _SiO2 content in the carrier to 15%, and the other material consumption and operating conditions are the same as Example 1, namely the product E of this example.

Comparative example 1

In this comparative example, the carrier was prepared according to the method described in CN1289636A.

Weigh 298g of aluminum hydroxide powder containing 67w% Al ₂ O ₃ , add it into 3000cm ³ of water under stirring to make a slurry; keep stirring, add 37cm ^{3 of} 5% ammonia water dropwise to the above slurry, and the pH value of the slurry is 7.35; Continue to stir, add dropwise 5% ammoniacal liquor and 2.8% (calculated as _TiO ) titanium sulfate solution in the above-mentioned slurry, in the process, the pH value of the solution fluctuates between 7.5～9; when the titanium sulfate solution add-on reaches 635 cm ^When ( The amount of 5% ammonia water is 496cm ³ ), stop adding the solution, continue to stir for 0.5 hours, then filter the above slurry, wash the obtained filter cake with clean water for 4 times, dry at 120°C for 6 hours, and then crush it to 180 mesh, that is, Cost Example Product F.

Comparative example 2

In this comparative example, the carrier was prepared according to the method described in CN1350882A.

Compared with Example 1, the ultrasonic transducer is stopped to emit ultrasonic waves, and the amount of other materials and operating conditions are the same as in Example 1, that is, the product G of this example.

The properties of the above materials after being calcined at 500°C for 3 hours are shown in Table 1.

Table 1 The physical and chemical properties of each example product

Physical and chemical properties Pore volume ml/g Specific surface m ² /g Average pore size/nm Infrared acid mmol/g Dispersion I _Ti /I _Al Dispersion I _Si /I _Al TiO ₂ w% SiO ₂ w% A 1.12 365 12.3 0.35 0.33 0.23 10.4 8.1 B 1.08 356 12.2 0.38 0.35 0.25 10.3 8.0 C 1.04 345 12.1 0.36 0.37 0.26 10.4 8.2 D. 0.99 337 11.8 0.35 0.33 0.22 15.3 7.9 E. 1.05 342 12.3 0.42 0.32 0.23 10.2 15.1 f 0.71 328 9.0 0.15 0.21 - 9.4 - G 0.91 317 11.5 0.34 0.19 0.18 10.3 8.1

As can be seen from Table 1, in the process of preparing aluminum hydroxide by the carbonization method, titanium and silicon are introduced by ultrasonic waves, and the pore volume, specific surface area, and average pore diameter of aluminum hydroxide become larger; the infrared acid value of the carrier also becomes larger; The dispersion value of titanium and silicon on the surface of aluminum hydroxide also becomes larger, indicating that the dispersion of titanium and silicon on the surface of aluminum hydroxide is more uniform.

The method for measuring the metal dispersion in the present invention is X-ray photoelectron spectroscopy, and the larger the dispersion value is, the more uniform the metal is dispersed in the alumina.

Claims (14)

1, the aluminium hydroxide of a kind of titaniferous and silicon is characterized in that containing titanium dioxide 1～20w% behind the Aluminium hydroxide roasting of this titaniferous and silicon, and silica 1～20w%, pore volume are 0.9～1.2ml/g, and specific surface is 360～450m ²/ g, average pore size is 10～15nm, the decentralization I of titanium on aluminium oxide _Ti/ I _AlBe more than 0.3, the decentralization I of silicon on aluminium oxide _Si/ I _AlBe more than 0.2.

2, according to the described aluminium hydroxide of claim 1, it is characterized in that described content of titanium dioxide is 5～15w%, dioxide-containing silica is 2～15w%, the decentralization I of titanium on aluminium oxide _Ti/ I _AlBe 0.3～0.4, the decentralization I of silicon on aluminium oxide _Si/ I _AlBe 0.2～0.3.

3, the preparation method of the aluminium hydroxide of described titaniferous of a kind of claim 1 and silicon, it is characterized in that adopting following process: sodium aluminate solution, titanium-containing compound slurries, silicon-containing compound solution and carbon dioxide are reacted into glue under stirring condition, the aluminium hydroxide product that filter then, wash, drying promptly makes final titaniferous and silicon wherein becomes the glue process to carry out under the ultrasonic wave effect.

4, in accordance with the method for claim 3, it is characterized in that described frequency of ultrasonic is 10～180kHz, ultrasonic power proportionately glue volume of material is counted 0.01～20W/mL.

5, in accordance with the method for claim 3, it is characterized in that described frequency of ultrasonic is 20～100kHz, ultrasonic power proportionately glue volume of material is counted 0.05～10W/mL.

6, in accordance with the method for claim 3, the concentration that it is characterized in that described sodium aluminate solution is 5～60g Al ₂O ₃/ l, the titanium-containing compound slurries become granularity less than 65 μ m slurry like material by metatitanic acid, titanium dioxide through adding water mill, and thin up is 5～40g TiO ₂/ l.

7, in accordance with the method for claim 6, the pH value that it is characterized in that described titanium-containing compound slurries is 7～11, and the addition of titanium-containing compound slurries is benchmark with final products, and wherein containing titanium dioxide is 1～20w%.

8, in accordance with the method for claim 3, it is characterized in that described silicon-containing compound solution is sodium silicate solution or silicon sol solution, concentration is 5～40g SiO ₂/ l.

9, in accordance with the method for claim 3, silicon-containing compound solution addition is benchmark with final products, and wherein containing silica is 1～20w%.

10, in accordance with the method for claim 3, it is characterized in that described one-tenth glue temperature is 10～45 ℃, concentration of carbon dioxide is controlled at 10～50v%, is controlled to the glue slurry pH value and is at 9～12 o'clock and stop logical carbon dioxide.

11, in accordance with the method for claim 3, it is characterized in that described washing for spending deionised water 1～5 time, contains Na to the aluminium hydroxide of preparation ⁺By weight＜0.05%, drying is following dry 2～12 hours at 80～180 ℃.

12, in accordance with the method for claim 7, the addition that it is characterized in that described titanium compound slurries is benchmark with final products, and wherein containing titanium dioxide is 2～15w%.

13, in accordance with the method for claim 9, it is characterized in that described silicon-containing compound solution addition is benchmark with final products, wherein containing silica is 2～15w%.

14, the application of aluminium hydroxide in hydrogenation catalyst of described titaniferous of a kind of claim 1 and silicon, it is characterized in that with this Ti-contained aluminium hydroxide be raw material, make hydrogenation catalyst through moulding-roasting-dipping-roasting process or through mixed pinching-moulding-roasting process or through mixed pinching-moulding-roasting-dipping-roasting process, wherein roasting condition is 350～800 ℃ of following roastings of air atmosphere 1～10 hour.