Study On The Anti-agglomeration Of Silica By Hydrolysis Of Chlorosilane

With the rapid development of China's market economy,silica as an inorganic non-metallic material,showing strong adsorption capacity,high temperature,chemical stability and other excellent performance is widely used.However,the application of silica has been inhibited.Because of its small particle size,large surface atom proportion,larger surface area,large surface energy and unstable state,it is easy to agglomerate and agglomerate,in addition,it seriously effect the morphology of silica in the generation process.Chlorosilane residue,is the byproduct in polysilicon industry with the characteristics of high yield and chemical instability.Furthermore,it can rapidly produce silica and hydrogen chloride in hydrolysis reaction.Therefore at present,most domestic enterprises focus more on chlorine recycling than silicon when recycling chlorosilane residue.Yet,the most common way to recycle chlorine is the lye neutralization,which cause silicon waste.To solve these problems,in order to improve the dispersion of silica and obtain better quality silica,the mechanism of silica preperation in the hydrolysis of chlorosilane has been reaserched.The preparation of silica powder by the solution of p-chlorosilane residue liquid-liquid hydrolysis and gas-liquid hydrolysis reaction and post-drying of acid-containing silica gel showed that:1)When the residual liquid is in contact with water,The surface molecules compete with water molecules and undergo a rapid reaction to produce localized high temperatures,allowing rapid formation of large amounts of silica primary particles on the surface of the raffinate droplets and quickly aggregating to form irregular fluffy silica,The internal encapsulation of chlorosilane residue hinder the contact of the residue with water,making the hydrolysis reaction is not complete,the product of silica particles by the local chemical energy impact caused by the phenomenon of hardening of silica particles,so that it Particle size becomes larger,affecting the quality of the product.And the gas-liquid contact reaction of the hydrolysis of the production of silica products showing a granular and good dispersion,but the particles by the intermolecular electrostatic force or van der Waals force in a short time(less than 2h)will still polymerization reunion;2)(PH-9)can control the silica particle size around 2?m.and the particle size of the silica is higher than 100?m when washed to neutral or acidic state,and the particle size of the silica is higher than 100?m.Drying temperature and other conditions have changed the quality of the reorganized silica has little effect.In the chlorosilane residue hydrolysis experiment,a method of agglomeration of the silica samples was carried out by means of an optical microscope and an scanning electron microscope.The particle state of the silica in the reaction solution was measured by optical microscopy to more quickly and efficiently It is concluded that it is more economical and can be used in the study on the agglomeration of silica obtained by hydrolysis of chlorosilane residues.It is suggested that the glycerol steric hindrance is applied to the hydrolysis system,and its high viscosity properties can play a role in hindering the rapid movement of silica and agglomeration.It can prolong the action time of the steric hindrance for about 2h,Of the silica particles become rounded,full,the particle characteristics are obvious;but the steric hindrance of the product of silica particles is a time limit of the role of time constraints,with the migration of time,because of its own nature of silica It is also found that the introduction of electrolyte agents in the hydrolysis system alone does not change the physical properties of the product silica,but the introduction of electrolyte ammoni?m chloride can make the resistance agent C The presence of electrolyte in the trioxide determines the effect of the formation of the electrolyte,which in turn affects the formation of the double layer of the silica particles,which in turn affects the duration of the action of the steric hindrance.The amount of residual liquid in the hydrolyzate per unit vol?me is less,the longer the action time of the steric hindrance is.the amount of steric hindrance is about half of the total vol?me,the role of the steric reactant can be reflected,and the amount of the steric inhibitor is controlled And the amount of residue into the relationship between the amount of steric role in order to play the best.The analysis of the principle of gas-liquid hydrolysis reaction system was carried out.It was found that the addition of viscous and stable steric hindrance to the system showed that the particles of the product silica were more round and smooth,and the degree of dispersion was more obvious.The effective force to contain the intermolecular force so that the time of polymerization of silica particles agglomeration time extended to 6h or so.Similarly,the duration of the role of the steric agent will be affected by some conditions such as stirring,stirring can extend the role of steric hinders about 1h.In this paper,the introduction of steric hindrance and electrolyte in chlorosilane residue hydrolysis system,the preparation of silica by gas-liquid reaction method can effectively solve the problem of silica agglomeration,and can realize the high value-added recycling of silane silane residue,Turning waste into treasure to reduce environmental pollution has great practical significance.