Preparation Of Novel Super Microporous Silica Materials And Study On Desulfurization And Dyeing Removale Performance

Porous silica materials are good candidates for adsorbents because of their high specific surface area,large pore volume,high thermal stability,weak surface interaction and good biocompatibility.However,due to the diffusion resistance of microporous materials,especially the diffusion of molecules with large steric resistance in microporous materials,the application of traditional microporous silica materials in adsorption is limited.Traditional mesoporous silica materials have no diffusion limitation but lose shape selectivity.Super Microporous Silica with pore sizes ranging from 1.0～2.0 nm,is more suitable for molecular shape selective catalysis and molecular separation(adsorption)than microporous and mesoporous silica.In this paper,by using a triblock copolymer surfactant Polyethylene Oxide-Polypropylene Oxide-Polyethylene Oxide PEO-PPO-PEO under mild conditions,hydrothermal synthesis method was used to prepare a novel ultrafine silica(SMS)silicon-based material,the main pore size distribution around 1.2 nm,and part of 1.6 nm.Because of its unique aperture structure,the material solves the problems of diffusion resistance of traditional micropores and poor shape selection of mesoporous materials.(1)The synthesis conditions were optimized by contrast experiments.The optimum crystallization temperature was 100~oC and crystallization time was 24 h.The synthesized material had a specific surface area of 1098 m~2/g and a pore structure mainly distributed near1.2 nm and a small part distributed at 1.6 nm.The samples were analyzed by X-ray diffraction(XRD).The samples were confirmed to be silicon oxide by comparing with the traditional XRD patterns of mesoporous silicon dioxide.Nitrogen adsorption-desorption test was carried out on the sample.The results of nitrogen adsorption isotherm and pore size distribution showed that the microporous silicon oxide was successfully synthesized.(2)The synthetic microporous silica material was applied to fuel desulfurization,and the process of fuel desulfurization was simulated by removing quantitative benzothiophene mixed in n-octane.The desulfurization performance of the adsorbent was tested by static and fixed bed adsorption respectively.The results showed that the SMS material could capture 0.122mmol S/g at the crystallization temperature of 100~oC,which was better than the traditional mesoporous silica material KIT-6.In addition,after three regeneration experiments,benzothiophene adsorption activity can be well recovered without obvious loss.SMS material is easy to synthesize,has good thermal stability and regeneration ability,which is conducive to the application of adsorption desulfurization technology.(3)The adsorption of methylene blue in water was studied by using the synthesized microporous silica material in dye removal.Dynamic adsorption and static adsorption were carried out respectively.Uv spectrophotometer was used to measure the adsorption results,and the results were as follows:the crystallization temperature of 100~oC,crystallization time of 24h,the best adsorption effect of ultrafine silica,reaction time of 1 h,the maximum adsorption capacity of methylene blue attained 22 mg/g under acidic environment.