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用XPS,IR,TG和脉冲色谱法考察了V_2O_5-TiO_2复合氧化物催化剂中V_2O_5与TiO_2的相互作用,V_2O_5的分散状态和释氧活性,以及催化剂对邻二甲苯氧化的活性和生成苯酐的选择性。阐明了该催化剂组成对活性和选择性的影响。XPS和TG结果表明,V_2O_5含量<10wt%时,它与TiO_2可形成有V_2O_5与TiO_2相互作用和释氧活性的表面层;在V_2O_5含量～10wt%时,该表面层形成得最充分。IR研究证实表面层的释氧活性是由V_2O_5的V=O键松弛引起。V_2O_5>10wt%时,样品中除有释氧活性的V_2O_5外,还有不具有释氧活性的V_2O_5,前者对催化活性和选择性有主要贡献,后者则有不利影响。
The interaction between V 2 O 5 and TiO 2 in V 2 O 5 -TiO 2 composite oxide catalyst, the dispersion state and oxygen release activity of V 2 O 5, the activity of the catalyst for o-xylene oxidation and the selection of phthalic anhydride were investigated by XPS, IR, TG and pulse chromatography Sex. The effect of the catalyst composition on activity and selectivity is elucidated. The results of XPS and TG show that when the content of V2O5 is less than 10wt%, it can form the surface layer with the interaction of V2O5 and TiO_2 and the oxygen releasing activity with TiO_2. When the content of V_2O_5 is 10wt%, the surface layer is formed the most. IR studies confirm that the oxygen release activity of the surface layer is caused by the V = O bond relaxation of V 2 O 5. V_2O_5> 10wt%, in addition to V_2O_5 with oxygen releasing activity, there is V_2O_5 with no oxygen release activity, the former has a major contribution to the catalytic activity and selectivity, while the latter has an adverse effect.