摘要
加热温度低于580℃时,V_2O_5/TiO_2催化剂体系内的V_2O_5在TiO_2表面上分散,此时虽有部分V_2O_5碎片渗入TiO_2表层,但还未形成固溶体。在此阶段,随温度的提高,无定形的V=O键伸缩振动(980cm^(-1))先是生成,后逐步消失;V—O—V键的伸缩振动(862cm^(-1))显著减弱,并紫移到885cm^(-1);新出现了1400cm^(-1)吸收峰,它是V_2O_5一级结构及其集合体的表征。同时,在TiO_2的宽频区出现了740,670和594cm(-1)三个吸收峰,这可能是Ti^(4+)d轨道在VO_4影响下能级分裂的结果。580℃到677℃,形成等一类固溶体,上述1400cm^(-1)吸收峰消失,740,670和594cm^(-1)三峰也逐步合一,这是固溶体中V-O-Ti键振动的象征。>677℃,第二类固溶体(V_xTi_(1-x)O_2)出现,其红外光谱同第一类固溶体,但TG有失重。
When V2O5/TiO2 catalyst was calcined below 580℃, V2O6 dispersed on TiO2 surface, and no solid solution was formed although some fragments of V2O5 permeated into the surface layer of TiO2. As the calcination temperature increased from 400 to 580℃, 980cm-1 band of amorphous V-O stretching vibration appeared and then disappeared gradually, 862cm-1 band of V-O-V stretching vibration was much weakened and shifted to 885cm-1,and a new absorption peak of 1400cm-1 appeared. At the same time, 740,670 and 594cm-1 peaks emerged in the broad frequency band of TiO2. First kind of solid solution was formed in the calcined temperature range of 580-677℃, meanwhile, the above-mentioned 1400cm-1 peak disappeared, and 740, 670 and 594cm-1 peaks merged in one broad frequency band which was assigned to the vibration of V-O-Ti bond of the solid solution. The second kind of solid solution( VxTi1-xO2) was formed under calcination at above 677℃, its IR spectra were similar to that of first kind of solid solution, but loss of weight was observed in TG curve.
基金
国家自然科学基金
