Dissertation > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst

The Study of Preparation and Photocatalytic of Compound Nanomaterials TiO2/Fe2O3 and TiO2/SnO2

Author RaoXing
Tutor LiuHuaZhang; LvDeYi
School Zhejiang University of Technology
Course Industrial Catalysis
Keywords peptization-hydrothermal crystallization method compound photocatalytic TiO2/Fe2O3 TiO2/SnO2
CLC O643.36
Type Master's thesis
Year 2009
Downloads 177
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Although nanometer TiO2 has considered the most promising photocatalyst,it can only absorb less than 387 nm light because its band gap reaches 3.2 eV;and the life expectancy of those excited electron-hole is very short.These two fatal defects limited the scope of application.Thence, the primary problem of current research is to modify the TiO2 to improve the performance of its optical absorption and optical quantum efficiency. Among them,the study hotspot is to adopt different oxides to form composite semiconductor,this way could effective enhance its photocatalytic activity.Used peptization-hydrothermal crystallization method,this paper prepared composite nanometer catalyst of TiO2/Fe2O3、TiO2/SnO2.At first, through research-based nano-composite catalyst TiO2/Fe2O3 crystal structure,particle images,UV-Vis absorption performance,photocatalytic and the energy band structure between TiO2 and Fe2O3,Analysis showed that:The energy band of these two oxides in the composite photocatalyst must be met the principle of energy band,which means the valence band and conduction band charged potential of modified oxide higher than TiO2.Based on peptization-hydrothermal crystallization method,the paper used three ways to prepare composite TiO2/SnO2 samples,and researched crystalline structure,particle images,UV-vis absorption performance of composite samples based on these analytical instrument:XRD,SEM, UV-vis.Then,this paper researched the photocatalytic activity of TiO2/SnO2 used the means of degrading methyl orange.The study shows that:①A-TiO2/SnO2 is continuous replacement solid solution structure,which preparation is focuses on adding Sn4+.The TiO2 form Rutile phase because of adding Sn4+,and with Sn4+content increasing, those various performances of solid solution converse to SnO2 performances gradually,and the photocatalytic trend is reduced at first,and then increased.②The preparation of B-TiO2/SnO2 come from adding Sn(OH)4.The crystal structure of TiO2 is mixed phase of anatase and rutile in these products of TiO2/SnO2.Sn(OH)4 play the same effect to the rutile phase conversion of TiO2 as Sn4+.When the time of adding Sn(OH)4 is postponed,the weight ratio of rutile phase-TiO2 in the composite is decreased,and when the weight ratio of adding Sn(OH)4 is increased,the weight ratio of rutile phase-TiO2 is increased.③The preparation of C-TiO2/SnO2 come from adding SnO2.The crystal structure of TiO2 is anatase phase in these products of TiO2/SnO2.This paper investigated four factors-the heat treatment temperature of SnO2,the quality ratio of SnO2, peptization temperature and concentration of HNO3,these factors play the important impact on the crystal structure,composite morphology,UV-vis absorption properties of compound Anatase-TiO2/SnO2.The best process parameter to photocatalytic activity:the heat treatment temperature of SnO2 is 300℃,the weight proportion of SnO2 is 40%, peptization temperature is 50℃and Nitrate concentration is 4mol/L.The compound TiO2/SnO2 samples reached 94.5%in the process of degrading methyl orange in 45 min,and increased 52.5%more than non-modified TiO2.

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