| It is a challenging task to prepare visible light responsive catalysts for partial oxidation of methanol to methyl formate（MF）.Based on the theoretical calculation,TiO2 catalysts doped by different metals were prepared and characterized.The photocatalytic performance of methanol to methyl formate was investigated,and the"structure-activity relationship"of the catalysts was discussed.Specific research contents and results are as follows.1.The calculation results based on the first principles showed that when TiO2 was doped with Sn,Pb and Bi,the band gaps of the catalysts were all reduced,and the optical absorption band edges of the samples were all red shifted.After doping with Bi atom,the impurity level of Bi 6s orbital appeared between the conduction band and valence band of TiO2,which reduced the excitation energy of valence band electrons and extends the optical response range of the catalyst to the visible region.2.The effects of drying method,calcination temperature and heteroatom content on the properties of the catalyst were investigated.It was found that the supercritical drying method was beneficial to the dispersion of catalyst particles and increased the number of surface active groups.The calcination temperature has a strong correlation with the crystallinity of the sample and the number of surface hydroxyl groups.The heteroatom concentration was related to the light absorption of the catalyst.The best photocatalytic performance of methanol to methyl formate was obtained on 0.5Bi-TiO2sample.The methanol conversion reached 61.36%,and the methyl formate formation rate reached 2.0388 mmol/g/h.3.Sn,Pb and Bi can be doped into the lattice of anatase TiO2.The doping of metal increased the surface hydroxyl group,reduced the band gap and increased the valence band edge energy（VBE）of the catalyst.Only catalysts with appropriate valence band and sufficient surface hydroxyl groups can achieve high methanol conversion and methyl formate selectivity. |
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