Process for preparing size-controllable nano-silicon dioxide

A nano-silicon dioxide and size technology, applied in the preparation of silicon dioxide, silicon oxide, oxide/hydroxide, etc., can solve the problems of poor cooling effect, sintering into large particles, and difficult size, so as to improve the cooling effect. Efficiency and effect of preventing particle size increase

Inactive Publication Date: 2004-11-17

GUANGZHOU GBS HIGH TECH & IND

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AI-Extracted Technical Summary

Problems solved by technology

[0004] In the production process of fumed silica, the cooling of the combustion chamber is a key process, because in the process of silica preparation, the reaction temperature is basically above 1700°C (above the melting point of silica), and immediately after the reaction is completed Keep the temperature in the reaction chamber below 800°C, otherwise the formed silica particles are likely to collide with each other and sinter into lar...

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Method used

In the present invention, the cooling of the combustion chamber is to implement an open mode between the combustion nozzle 1 and the combustion chamber 3, so that the outside air can enter the reaction chamber from the combustion chamber opening 2 by the negative pressure in the combustion chamber to play the role of cooling Function, the cooling method of the combustion chamber jacket adopts water cooling instead of the traditional air cooling, the cooling water enters from the inlet 11, 13, flows out from the outlet 12, 14, the cooling water returns to reuse after cooling, this method improves the The cooling efficiency can reduce the temperature in the reaction chamber from above 1400°C to below 800°C instantly, which can effectively control the parti...

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Abstract

The invention provides a process for preparing dimension controllable nano silicon dioxide comprising continuously conveying organic halogensilane, hydrogen, and oxygen by a finite proportion into combustion nozzle then firing chamber, conducting hydrolytic reaction in 1000 deg. C to 2000deg. C flame, subjecting the reaction product to congregation, cyclone air-solid segregation and deacidification post-treatment, and vacuum-packing.

Application Domain

Oxide/hydroxide preparationSilica

Technology Topic

ChemistryCombustion chamber +9

Image

Examples

Experimental program(3)

Example Embodiment

[0021] Example 1

[0022] Take methyl trichlorosilane to 7.5m 3 /h, hydrogen is 12m 3 /h, the air is 105m 3 The supply of /h is continuously delivered to the premixer for premixing (the above volume is the standard volume), and then enters the burner nozzle after preheating to 120°C. The specific process is shown in Figure 1. The temperature in the reaction chamber is 720°C. The temperature in the second-stage deacidification furnace is 600°C, the temperature in the second-stage deacidification furnace is 550°C, the auxiliary gas for deacidification is steam and nitrogen, and the temperature is 230°C. The quality indicators of the produced silica are as follows:

[0023] Silica content (%) (hydrofluoric acid method) 99.85

[0024] Average particle size of primary particles (nm) (electron microscopy) 30

[0025] Specific surface area (m2 /g) (BET method) 153

[0026] PH value (4% water suspension) 3.95

[0027] Carbon content (%) 0.01

Example Embodiment

[0028] Example 2

[0029] The methyl trichlorosilane of Example 1 was replaced by silicon tetrachloride, and the silicon tetrachloride was replaced by 7m 3 /h, hydrogen is 15m 3 /h, air at 130m 3 /h supply, the process is the same as in Example 1, the temperature in the reaction chamber is 640°C, and the others are the same as in Example 1. The quality indicators of the prepared silica are as follows:

[0030] Silica content (%) (hydrofluoric acid method) 99.85

[0031] Average particle size of primary particles (nm) (electron microscopy) 12

[0032] Specific surface area (m 2 /g) (BET method) 283

[0033] PH value (4% water suspension) 4.05

[0034] Carbon content (%) not measured

Example Embodiment

[0035] Example 3

[0036] Replace the methyltrichlorosilane in Example 1 with 60% methyltrichlorosilane and 40% silicon tetrachloride, and the supply amount is 8.5m 3 /h, hydrogen is 16m 3 /h, the air is 125m 3 /h, the temperature in the reaction chamber is 690°C, and other process parameters are the same as in Example 1. The quality indicators of the prepared silica are as follows:

[0037] Silica content (%) (hydrofluoric acid method) 99.82

[0038] Average particle size of primary particles (nm) (electron microscopy) 15

[0039] Specific surface area (m 2 /g) (BET method) 208

[0040] PH value (4% water suspension) 4.23

[0041] Carbon content (%) 0.01

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Description & Claims & Application Information

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Classification and recommendation of technical efficacy words

Improve cooling efficiency

Process for preparing size-controllable nano-silicon dioxide

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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