High-dispersion nano silicon dioxide preparation method

Abstract

The invention discloses a method to prepare high-disperse nano SiO2, imputting O2-H2 organic halogen silane in a certain proportion into reaction room to make burning reaction, at the same time inputting a protective gas, vapor and inert gases, adopting the produced water and heat to make high-temperature hydrolytic condensation reaction and making the late process such as aggregative gas-solid separation deacidification on the reaction product to obtain it, primary particle dimaeter 7-40 nm, ratio surface area 100-400 m2 / g, pH value 3.8-4.5, SiO2 receiving rate >99%.

Description

Technical field [0001] The invention relates to a preparation method of highly dispersed nano silicon dioxide. Background technique [0002] Due to its unique physical and chemical properties, highly dispersed nano-silica is widely used in the fields of rubber, plastics, coatings, paint inks, adhesives, cosmetics, medicine, agriculture, etc., to strengthen, thicken, thixotropy, extinction, Anti-settling, anti-sagging and anti-aging effects. At present, the methods for preparing highly dispersed nano-silica can be divided into two types, one is the wet method, which uses a silicate solution (such as sodium silicate) to hydrolyze under acidic or alkaline conditions, and then undergoes a series of post-treatments. Process to obtain silica, also known as precipitated white carbon black, the other is dry method, using organosilicon halides (such as silicon tetrachloride, methyl trichlorosilane, etc.) to obtain silica by flame high temperature hydrolysis Airgel, and then through...

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Problems solved by technology

[0003] The production process of fumed silica was first developed by German Degussa company in 1941. However, only a few countries in the world, such as Germany, the United States, Japan, Ukraine and China, have mastered the industrial production technology of fumed silica. Traditional The production process of fumed silica is basically similar. First, the vaporized halosilane is mixed with hydrogen and oxygen, and then burned in a combustion chamber (reaction chamber) to obtain silica aerogel, which is then aggregated through an aggregator. Then through gas-solid separation (such as gravity sedimentation, cyclone separator separation, centrifugal separator separation, impact separator separation) to separate the solid product from the reaction waste gas and unreacted gas, and then through the deacidification process, the adsorbed on the silica The hydrogen halide gas on the surface is removed, so as to obtain the finished product. For specific methods, see U.S. Patent 418964, 3954945 and 4048290 and Chinese Patent CN 1043633C, etc. However, in the traditional method, the fumed silica particles are easy to deposit on the reaction chamber wall. With the extension of time, the deposited silica particles will reduce the size of the reaction chamber, which will affect the geometric size and shape of the reaction flame, and finally affect the uniformity and quality of the product. Sometimes during the production process, the mechanical cleaning reaction must be stopped room, affecting the continuity of production

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