SU1139701A1 - Method of obtaining hollow microspherical particles of silicon dioxide - Google Patents

Abstract

1. METHOD FOR OBTAINING EMPTY MICROSPHERIC PARTICLES OF SILICON BIOXIDE, which includes mixing piercegenic silica with water, spray drying the resulting suspension, followed by calcining the product, in order to improve the quality of the product and reduce the process time, followed by calcining the product, in order to improve the quality of the product and reduce the process time, after the process, it is a heartbeat, and heartbeat, to put heartbeat patterns, as to be used, to set the quality of the product and reduce the process time, to carry out the process, it will be a heartbeat, and heart-to-do process, should be used, should be used, should be used, should be used, should be used, should be used, should be used to create a heartbeat, heartbeat, heartbeat, and to put to the process, should be a heartbeat, a heartbeat will be used, as well as to be used, should be used, should be used, should be used, should be used, should be used, should be used, should be used, should be used, should be used, should be used, should be used, should be used to carry out the process. substances taken in the amount of 0.052, 0% by weight of silicon dioxide. 2. A method according to claim 1, characterized in that the polycondensation products of ethylene glycol or the reaction of ethylene oxide with ethylene glycol are used as surface-active substances.

Description

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This invention relates to methods for producing hollow microspheroidal silica particles that can be used as adsorbents, catalyst carriers, fillers for paints and polymers.

A method of producing hollow microspheroidal silica particles is known, comprising mixing silica obtained in an electric arc with water, drying the resulting suspension, followed by calcining the product 13.

The disadvantage of this method is the low yield of thin-walled hollow microspheric silica particles.

The closest to the proposed technical essence and the achieved result is the method of obtaining a void to the microspheric particles of metal oxides and metalloidge, including spray drying an aqueous suspension of a hydrophilic compound, followed by calcining. In addition, 15-80 wt.% In terms of

dry matter hydrophobic oxide with a specific surface area of 20-400

As a hydrophobic oxide, an oxide is used, 25-75% of the surface hydroxides of which are substituted by alkylsilyl I groups, and calcining is carried out at 50-1800 ° C 2.

The disadvantages of this method are the low quality of the product obtained, i.e. size heterogeneity of the particles obtained, increased shell thickness, and the need for long (2 hours) mixing of the initial mixture to obtain uniform suspensions.

The purpose of the invention is to improve product quality and reduce process time.

The goal is achieved according to the method of obtaining hollow microspherical silica particles, including mixing pyrogenic silicon dioxide with water, the spraying essence of the resulting suspension, followed by calcining the product, while mixing is carried out in the presence of a non-ionic surfactant, taken in an amount of 0.05-2.0 % by weight of silica.

Products are used as surfactants.

ethylene glycol polycondensation or interaction of ethylene oxide with ethylene glycol.

According to the proposed method, fumed silicon dioxide with a specific surface (BET) of 60-400 m / g and a bulk weight of 40-120 g / l is introduced, by intensive stirring, into an aqueous solution of non-ionic surfactant, whose content in the solution depends on the amount of silica and is 0.05-2% of its weight. The suspension is stirred for 20 minutes. PEG-35, PEG-115, which are ethylene glycol polycondensation products, are used as nonionic surfactants. OC-20 is a product of the interaction of ethylene oxide with ethylene glycol. The silica content of the suspension is determined by the sprayability requirement, depending on the specific surface area of the silica and is 10-40%. The resulting mixture is dispersed by feeding it under pressure through a spray nozzle into a drying column, the temperature inside of which is 150,500 s and kept constant with the power of the electric heating elements. When the sprayed suspension gets into the zone of elevated temperatures, the process of expansion of the suspension droplets and evaporation of water from their surface occurs. The presence of surfactant impurities in the mixed mixture contributes to the swelling of the droplets and the subsequent formation of thick walled hollow microspheres due to the presence of air bubbles in such a mass. The product obtained as a result of spray drying is calcined at 800 × 1200 ° C in order to increase its strength.

The goal is achieved using only non-ionic surfactants. In the case of using ionic, for example, cationic surfactants, the performance characteristics of hollow silicon dioxide microspherical particles are reduced, since the ions introduced into the suspension contribute to the crystallization of amorphous silicon dioxide during calcination.

When less than 0.05% of a non-ionic surfactant is introduced into the suspension, the content of hollow microspherical particles in the resulting product decreases sharply. When more than 2% nonionic surfactant is introduced into the suspension, intensive foaming of the resulting suspension occurs, which worsens the conditions of the spray drying process and reduces the yield of hollow microspherical particles. Example 1. 20 kg of pyrogenic silicon dioxide with a bulk weight of 62 g / l and a specific surface of 362.3 are mixed for 20 mi with 60 kg of water and 0.006 kg (which corresponds to 0.03 wt.% By weight of silicon dioxide) non-ionic surfactant OS -20 Spray-dried particles are subjected to fractionation and calcination in air at 650 ° C. 15.7 kg (yield: 78.5%) of empty microspherical particles with a specific surface area of 308.3 are obtained, with a bulk weight of 215 g / l, a size of 90160 µm, and a shell thickness of 0.9-1.5 m. Example 2. 20 kg of pyrogenic silicon dioxide with a bulk weight of 120 g / l and a specific surface 186 are mixed with 60 kg of water and 0.01 kg of PEG-35, which corresponds to 0.05% by weight by weight of silicon dioxide, which is a product polyethylene condensation of ethylene glycol in a high speed mixer until a homogeneous fluid mass is obtained, which is then spray dried. oizvod through the spray nozzle under a pressure of 20 atm generated compressed air temperature in the drying tower is at the inlet 180 ° C at the outlet. The silica particles obtained as a result of spray drying are subjected to fractionation and calcination with. The resulting product in the amount of 17.7 kg has a thin layer of hollow-walled microspherical particles and is characterized by the following indicators: specific surface area (BET) 146 bulk density 354 g / l particle size of the main fraction 90160 MKMJ shell thickness 0.8-1.3 micron Particle yield 87.5%. Example 3. 20 kg of silicon dioxide silica with a total weight of 120 g / l and a specific surface area of 186 m / is mixed with 60 kg of water and U, Z kg. The OS-20 (which corresponds to 1.0 wt.%) Of the non-ionic p surfactant is in a high-speed mixer until a uniform fluid mass is obtained, which is then spray dried. The suspension is sprayed through a spray nozzle at a pressure of 20 atm. Generated by compressed air. The temperature in the drying column is 180 ° C at the inlet and 400 ° C at the outlet. The silica particles thus formed are calcined at 80.0 ° C. The result is 19.34 kg of thin-walled hollow silica microspherical particles with the following characteristics: specific surface area (BET) 169.7 bulk density 319 g / l particle size of the main fraction (prevailing particle size) 40-90 MKMJ shell thickness 0.5 -0.9 microns. The yield of particles is 96.7%. Example 4. Meter 4. 20 kg of pyrogenic silicon dioxide with a bulk weight of 120 g / l and a specific surface area (BET) 186 are mixed in a high-speed mixer with 60 kg of water and 0.4 kg of PEG-35 until a uniform fluid mass is obtained. which is sprayed through a nozzle using compressed air into a drying column, the inlet and outlet temperatures of which are respectively 180 and 400 C. The product formed after rapid drying is heated at 800 ° C. 18.9 kg of thin-walled hollow microspherical particles of silicon dioxide with a specific surface area (according to BET) 161 and a weight of 327 g / l are obtained. The particle size of the main fraction 60-120 MKMj shell thickness of 0.20, 65 microns. The yield of particles is 94.5%. Example 5. 20 kg of pyrogenic silicon dioxide with a bulk weight of 62 g / l and a specific surface of 62.3 Mix for 20 mi with 60 kg of water and 0.5 kg of non-ionic surfactant PEG-115, which corresponds to 2.5% by weight of dioxide silicon. After spray drying, the particles were fractionated and calcined in air at. 13.1 kg of hollow microspherical particles are obtained (yield 65.6%), the specific surface of which is 300.5 bulk density is 215 g / l, particle size is 50-180 µm and the sheath thickness is 0.24), 9.

S1139701

How much does the above application make getting more homogeneous?

ditch, the predictable method allows for the size of particles with a significant value to reduce the time of reading more thin shell

process, and also obes- (0.2-1.1 microns).

Claims (2)

1. METHOD FOR PRODUCING EMBEDDED MICROSPHERIC SILICON DIOXIDE PARTICLES, including mixing pyrogenic silicon dioxide with water, spray drying the resulting suspension, followed by calcining the product, characterized in that, in order to improve the quality of the product and reduce the process time, the mixture is surface-inactive substances taken in an amount of 0.052.0% by weight of silicon dioxide. 2. The method of pop. 1, characterized in that the products of polycondensation of ethylene glycol or the interaction of ethylene oxide with ethylene glycol are used as a surfactant. di, 1.139701