Preparation Of Hydrophobic Silica Gel And Performance Evaluation Of Treating Oil And Gas

As a major consumer of crude oil,China imports more than 400 million tons of crude oil every year,which will not only cause a large amount of crude oil evaporation loss,but also damage the environment.A variety of organic gases volatilized in crude oil,including a variety of toxic hydrocarbons,of which n-hexane,benzene and its aromatic compounds are also carcinogenic.For the safety problem of activated carbon in the process of oil and gas recovery by adsorption method,this paper mainly studies the optimized preparation of hydrophobic modified silica gel and the influencing factors of its pore characteristics,and adsorbs n-hexane and benzene with modified silica gel.The main conclusions are as follows:(1)In this paper,silica gel was prepared with sodium silicate and tartaric acid with a modulus of 3.3.The pore properties of silica gel were effectively changed by adjusting the pH and temperature of the hydrosol,the size of the sol(water content),the aging temperature,and the mass fraction of sodium silicate.Preparation process of optimized silica gel obtained by using mixed modifier on this basis:The hydrogel was prepared by the mass fraction of 6.25%of sodium silicate and tartaric acid,was adjusted to pH 6.7,the temperature was 50?,and the hydrogel prepared by increasing the water content to the sol volume ratio of 2:1 was aged at 50?for 3h,After washing five times in 24h,it was modified with a modifier of trimethylchlorosilane:hexamethyldisiloxane:hexane:methanol=1:0.5:1:1 for 24h,then washed by n-hexane and heated at 200?for 1h.(2)The addition of graphene during the sol enhances the adsorption capacity and mechanical strength of the hydrophobic silica gel to some extent.The saturated silica gel obtained finally has a saturated adsorption amount of n-hexane of 0.56g/g,a specific surface area of 858m~2/g,a pore volume of 6.8cm~3/g,and a pore size of 8.7nm.(3)Comparing the adsorption behavior of n-hexane and benzene by self-made hydrophobic silica gel,industrial silica gel and activated carbon,it was found that the adsorption of n-hexane by self-made hydrophobic silica gel will agglomerate,resulting in a decrease in adsorption volume,which is longer than the industrial time from the breakthrough point to the equilibrium point.Silica gel,while in the process of adsorbing benzene,the hydrophobic silica adsorption equilibrium time is longer than industrial silica gel and activated carbon.The self-made hydrophobic silica gel has a penetrating curve of type I,and the mass transfer resistance is mainly caused by intraparticle diffusion resistance.Therefore,the pore characteristics of silica gel,including pore size distribution and specific surface area,are important factors affecting n-hexane adsorption.(4)Under the normal temperature,heating and vacuum desorption,the effect of vacuum degassing is better.Hydrophobic silica gel can remove 95%of the positive self in20min,and control the appropriate temperature,can also accelerate the desorption rate and increase the degree of desorption.