SU1743351A3 - Method of obtaining porous boehmite alumina or aluminium @@@-oxide monohydrate - Google Patents

Abstract

The invention relates to a method for producing an aluminum-containing product, in particular, to a method for producing porous boehmite alumina or a-alumina monohydrate. The purpose of the invention is to improve the quality of the product. For this, the alkoxide aluminum solution is subjected to hydrolysis. The obtained phase of alumina is fed into an autoclave with a stirrer and subjected to heat treatment with a stirrer circumference of 1.0-5 ohms / s and a water vapor pressure of (5-20) xyo & for 1-4 hours. This method allows for a narrow distribution of pore radii and a narrow distribution of maximum pores. 2 of p f-ly, 2 tables.

Description

The invention relates to a method for producing an aluminum-containing product, in particular, to a method for producing a porous boehmite | Linozem or monohydrate aluminum oxide.

A known method of producing porous boehmite alumina or alumina monohydrate by acid hydrolysis of an aqueous solution containing sodium aluminate, the resulting suspension is filtered and subjected to heat treatment in an autoclave at 150-250 ° C for 2-50 hours, which is preferably carried out after preliminary aging at temperature up to 60 ° C for up to 10 days in an air-tight and waterproof unit.

A disadvantage of the known method is the insufficient quality of the product obtained, due to the impossibility of controlling the maximum pore volume when the pore radii are distributed within 3-100 nm, which is a prerequisite for achieving optimal results when using the product as a catalyst carrier, used in particular for desulfurization and cleaning waste and exhaust gases.

The aim of the invention is to improve the quality of the product,

The goal is achieved by the method of obtaining porous boehmite alumina or α-alumina monohydrate, including hydrolysis of an aluminum-containing aqueous solution and subsequent heat treatment of the resulting suspension of boehmite alumina or α-alumina monohydrate in an autoclave, because I take an alumina-containing solution and take and heat treatment is carried out in an autoclave with a stirrer at a peripheral speed of the stirrer, equal to 1.0-5.0 m / s

Heat treatment is preferably carried out at a water vapor pressure of (5-20) 10 ° Pa, for 1-4 hours.

The heat treatment can be carried out continuously. In this case, it is advisable to use an apparatus equipped with 2-10, preferably 4-10, placed one above the other sections with installed

with

with

N

WITH

coke

with

in them, mixers made with the possibility of infinitely adjustable.

The hydrolysis is carried out under known conditions. In particular, it is conducted at an elevated temperature (60-100 ° C).

Example 1. A mixture of C2 C20-alcoholate aluminum, obtained as an intermediate product in the synthesis of alkanols by Ziegler, is mixed with fully desalted water in a mass ratio of 1: 1 and the resulting mixture is subjected to hydrolysis at a temperature of 90 ° C in a kettle equipped with a stirrer. In this case, two immiscible phases, an upper phase of the alcohol and a lower phase of alumina with water, containing 11% by weight of alumina are obtained.

50 kg of the lower phase are fed to an autoclave equipped with a stirrer. After reaching a water vapor pressure of 5; 105 Pa, which corresponds to 125 ° C, is heat treated for 30 minutes at a circumference of the stirrer speed of 2.30 m / s, corresponding to a rotational speed of the stirrer of 200 rpm. After sample preparation at 550 ° C for 3 hours, the distribution of pore radii is cumulatively measured in the usual manner by mercury porosimetry.

The following equation is used for the definition:

- (1-40080)

p where D is the pore diameter:

p is pressure;

In-contact angle.

Alumina analysis.

Distribution of pore radii mm:

Volume mg / g:

40.11

b0.18

80.32

100.64

150.73

200.75

300.76

400.76

500.77

1000.78

Maximum pore volume with a pore radius of 9 nm. Composition,%: alumina 77.5; silicon oxide 0.01; iron oxide 0.01; titanium oxide 0,006; alkali and alkaline earth metals 0,005; other elements 0.01. The bulk weight is 0.54 g / ml, the surface at 550 ° C for 3 h is 170 m / g, the crystallite size is 20 nm.

Example 2. Example 1 is repeated, with the difference that the heat treatment is carried out for 1 hour at a water vapor pressure of 15 10 Pa, which corresponds to

198 ° C. After spray drying the suspension, the following results are obtained. Alumina analysis. Distribution of pore radii, nm: Volume, mg / g:

40.01

100.03

150.11

200.28

0250,55

300.86

400.74

500.78

1000.90

5Maximum pore volume with radius

pores 27 nm.

Composition,%: alumina 78.6, silica 0.01; iron oxide 0.01; titanium oxide 0,005; alkali and alkaline earth metals 0.005; other elements 0.01 Bulk weight021 g / ml,

surface 105 m / g, crystallite size 28 nm.

Example 3. Example 1 is repeated with the 5 differences that the heat treatment is carried out for 3 hours at a pressure of water vapor equal to 23 105 Pa, which corresponds to 220 ° C. Get the following results. Alumina analysis

0 Distribution of pore radii, nm:

Volume mg / g:

40.02

100.03

200.10

5300.39

40-0.79

500,86

1001.04

The maximum pore volume with a radius of 0 pores is 41 nm.

Composition,%: alumina 80.5, silica 0.01; iron oxide 0.01; titanium oxide 0,005; alkali and alkaline earth metals 0.005; other elements 0.01 5. Bulk weight 0.12 g / ml, surface 93 m / g, crystallite size 40 nm.

Example 4. Example 1 is repeated, with the difference that the heat treatment is carried out at a peripheral speed of the stirrer of 0-1 m / s for 2 hours at a water vapor pressure of 20 105 Pa, which corresponds to 220 ° C.

After spray drying the suspension, the following results are obtained. 5 Volume in the range of 2-100 nm 0.8 mlg, the maximum pore volume with a pore radius of 12 nm. Composition,%: alumina 80.8; silicon oxide 0.01; iron oxide 0.01; titanium oxide 0,006; alkali and alkaline earth metals 0,005; other elements 0.01. The bulk weight is 0.41 g / ml, the surface is 120 m / g, the crystallite size is 20 nm.

Example 5. Example 1 is repeated with the difference that the heat treatment is carried out at a peripheral speed of the stirrer of 5 m / s for 2 hours at a water vapor pressure of 20 105 Pa. which corresponds to 220 ° C.

After spray drying the suspension, the following results are obtained. Pore volume in the range of 2-300 nm 1.5 ml / g. The maximum pore volume with a pore radius of 105 nm. Composition,%: alumina 83.5; silicon oxide 0.01; iron oxide 0.01; titanium oxide 0,006; alkali and alkaline earth metals 0.05; other elements 0.01; The bulk weight is 0.12 g / ml, the surface is 73 m2 / g, the crystallite size is 150 nm.

Example 6. Example 1 is repeated, with the difference that the heat treatment is carried out at a peripheral speed of the stirrer of 1 m / s for 4 hours at a water vapor pressure of 20 10 Pa, which corresponds to 220 ° C.

After spray drying the suspension, the following results are obtained. Pore volume in the range of 2-100 nm is 0.65 ml / g, the maximum pore volume with a pore radius of 8 nm. Composition,%: alumina 78.1; silicon oxide 0.01; iron oxide 0.01; titanium oxide 0,006; alkali and alkaline earth metals 0,005; other elements 0.01, a bulk weight of 0.50 g / ml, a surface of 180 m / g, a crystallite size of 12 nm.

Example 7. A mixture of C2-C20-alcoholate aluminum, obtained as an intermediate product in the synthesis of alkanols by Ziegler, is mixed with fully desalted water in a mass ratio of 1: 1 and the resulting mixture is subjected to hydrolysis at a temperature of 90 ° C in a kettle equipped with a stirrer. In this case, two immiscible phases are obtained, the upper phase of the alcohol and the lower phase of alumina with water, containing 10% by weight of alumina. 50 kg of the lower phase is served in the upper part

a vertical p-section autoclave, each section of which is equipped with an agitator. At the same time, water vapor is fed into the upper part of the autoclave under pressure.

The autoclave is provided with plates mounted between the stirrers, allowing a controlled passage of the slurry from one section to another, a section located under it.

In this case, the heat treatment time

1-3 h, and the pressure in the autoclave is 20–10 Pa, which corresponds to a temperature of 220 ° C. The speed of rotation of the agitator and thereby its circumferential speed change accordingly. After spray drying, the resulting alumina has the properties shown in Table 1.

Example 8. Example 7 is repeated with the difference that the heat treatment is carried out for 2 hours at a water vapor pressure of 1510 Pa, which corresponds to 198 ° C. The results are shown in table 2.

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Claims (3)

1. A method of producing porous boehmite alumina or α-alumina monohydrate, including hydrolysis of an aluminum-containing aqueous solution and subsequent heat treatment of the resulting suspension of boehmite alumina or monohydrate (L-alumina in an autoclave, characterized in that, in order to increase the quality of the product, an alkoxide aluminum solution is taken as the alumina-containing solution and the heat treatment is carried out in an autoclave with a stirrer at a tip speed of 1.0-5.0 m / s. 2. The method according to p. 1, about tl and h a y i and with the fact that the heat treatment is carried out at a water vapor pressure (5-20) 10 Pa for 1-4 hours. 3. The method according to p. 1 and 2, that is, that the heat treatment is carried out continuously Heat treatment time 1 h 130 220 265 350 Gablitz2 -J Jb SB GJ SL 81.1 81.6 82.1) 82.6 0.37 O.Z1 0.18 0.13 132 103 107 96 25 35 1 (2 60 0.010.06 0.010.05 0,020,10 0.020.09 0.20 0.09 0.15 0, 0.530.6 / 0.160.3 0.180.23 0.160.17 0.71 0.60 0.30 0.19 0.730.75 0.720.75 0.380.1 (8 0,220,23 0.76 0.77 0.65 0.26 0.77 O, / 9 0.79 0.29 0.770.79 0,800,86 0,891.00 O., 78 0.80 0.87 1.01 1.0: 0.800.85I 0,890,9823 1.051.23 (O 1,121.1 (375