Study On The Preparation Of Catalyst Grade Silicon Sol

The paper has studied the preparation process of catalyst grade silica sol,presents a method about preparation of silica sol particle size is about 20nm,silica sol concentration to 40%.The raw material is water glass,using ion exchange method to prepare the mother liquor silica sol.Silica sol particle growth is respectively using silica sol dripping directly method and silicon powder hydrolysis method,resulting in silica sol particle size reaches a certain size.Finally obtain the catalyst grade silicon sol by concentrating and aging.Through the single factor experiment,discusses the effect factors of silica sol mother liquor preparation,such as raw materials,pH value,dilute concentration of water glass solution,cation exchange resin bed flux and alkalization required dilute water glass volume and so on.Experimental results show:the raw materials needed to place for at least a month,the initial concentration of dilute sodium silicate solution 5%,flux was 0.45ml/cm2 · min and 0.30ml/cm2 · min when dilute sodium silicate solution and poly acid solution flow through the resin bed,the carbonation process add 20ml diluted water glass,pH value between 9?10,the average particle size of silica sol 10?12nm,The content of SiO2 is about 5.17%.At 110?,the mother liquor without the occurrence of gel in 10 days,proved the mother liquor obtained under this condition has good stability.Through the silica sol dripping directly method and silicon powder hydrolysis method,discusses the effect factors of the silica sol average particle size.Through the range and variance analysis,the optimum conditions was determined.Silica sol dripping directly method experimental results show:Silica sol liquor average grain diameter is 12.50nm,reaction time 7h,the stirring rate is 100r/min,the reaction temperature is maintained at 90 ?,the initial mother liquor of SiO2 is 5%,add the liquid silica sol and the bottom fluid volume ratio(by mass fraction of silica meter)of 20:1,concentration of silica sol added liquid(in mass fraction of silicon dioxide meter)is 8%,silica sol liquor dropping flux was 0.40 ml/cm2·min,the silicon sol product pH value is between 9-10,the average particle size between 19-21nm,Particle size distribution is uniform,the morphology is spherical,with obvious characteristics of the structure of silica sol.At 110?,the mother liquor without the occurrence of gel in 10 days,At room temperature for three months without the gelation,proved the mother liquor obtained under this condition has good stability.Silicon powder hydrolysis method experimental results show:Silica sol liquor average particle size of 12.50nm,the mother liquor concentration is 5%,silicon particle size control in 150,reaction temperature 90?,reaction time was 8h,the catalyst used for 10%dilute ammonia water,and the amount of ammonia is 10ml,silicon powder addition is 0.5g.The product pH value between 9?10,the average particle size between 19-21nm.Using this method,particle size distribution is more uniform,the morphology is spherical,with obvious characteristics of the structure of silica sol.The products Mass concentration is up to 40%After concentration.At 110?,the mother liquor without the occurrence of gel in 10 days,At room temperature for three months without the gelation,proved the mother liquor obtained under this condition has good stability.Concentration of silica sol through the nanofiltration membrane method,avoid silica sol gel,stick wall and system concentration is difficult to control in the traditional heating concentration...