Studies On Preparation And Catalytic Performance On Supported Catalyst Of Porous Silica Fibers

As the representative of the semiconductor material,Titanium dioxide has excellent photocatalytic activity and can be widely studied and used in the degradation of pollutants,the development of new renewable energy and other fields.Most of the titanium dioxide used in current studies is nanopowder,so it is inevitable that nanoparticles are easy to aggregate,the product is not easy to separate and recycling is cumbersome,etc.Inorganic porous materials are widely used due to its heat resistance,corrosion resistance,high specific surface area and other excellent properties.Electrospinning is an efficient method for the preparation of inorganic porous materials.Therefore,SiO₂ fibers with porous structure were prepared by electrospinning,and TiO₂ particles were compounded into supported SiO₂ fibers.The preparation method of porous SiO₂ fiber and the catalytic performance of porous fiber catalyst loaded with TiO₂ in photodegradation of methyl orange were studied.The contents of this thesis are as follows:?1?Porous SiO₂ fibers were prepared by calcing electrospun PVP/TEOS/P123 fibers.P123 was introduced as the template agent.With the increase of the P123 content in the electrospun solution,more pores and strips appeared.The diameter of fibers was about lum.The FTIR and XRD results confirmed that the component of porous fiber was SiO₂.When P123 content was 4.9 wt%,mesopores existed in the fiber.The specific surface area was 5.71 m²/g,and the average pore size was 7.093 nm.Porous SiO₂ fibers were prepared by calcing electrospun PAN/PVP fibers.PVP was used as the template agent.The FTIR,EDS and other results confirmed that the component of porous fiber was SiO₂.When PVP content was 10 wt.%,mesopores existed in the fiber.The specific surface area was 647.26 m²/g,and the average pore size was 2.3 nm.PS microspheres with a diameter of about 100 nm were prepared by emulsion polymerization.Porous SiO₂ fibers were prepared by calcing electrospun PVP/TEOS/PS fibers.PS was introduced as the template agent.With the increase of the PS content in the electrospun solution,there were more dotted protrusions on the surface of fibers.When PS content was 4.5 wt.%,mesopores existed in the fiber.The specific surface area was 5.52 m²/g and the average pore size was 7.94 nm.?2?Hollow SiO₂ fibers were prepared by coaxial electrospinning.The hollow fiber was observed when PVP is used in the core solution.The fiber diameter increased as inner electrospinning rate increased.When the core advance rate was 1.2 mL/h,the outside diameter and inside diameter of hollow fiber were 1 um and 633 nm,respectively.The FTIR,XRD and other results confirmed that the component of hollow fiber was SiO₂.?3?Finally,the SiO₂ porous fiber prepared from electrospinning PAN/PVP solution was chosen as the supporter of catalyst.Next,TiO₂/SiO₂ fibers were prepared by calcing TiO₂/SiO₂/PAN fibers.The porous fibers were characterized by SEM,XRD,FTIR and N2 adsorption,etc.The results showed that when the content of TiO₂ was 12.0 wt.%.TiO₂ particles with the size of 22.5 nm dispersed uniformtly on the surface of SiO₂ fibers.The fiber crystallinity was 99.80%,and the specific surface area was 238.72 m²/g.When the concentration of TiO₂ solution was 2.0 g/L,the photocatalytic degradation rate of methyl orange in the presence of porous TiO₂/SiO₂ fibers was 96.5%after exposed to UV-light for 120 min,which was higher than that?88.3%?of solid fiber TiO₂/SiO₂ fibers,indicating that the TiO₂/SiO₂ porous fiber catalyst has good photocatalytic activity.