甲苯气相选择氧化制苯甲醛　Ⅱ．锑对V_2O_5／TiO_2催化剂结构及反应性能的影响

Vapour Phase Catalytic Oxidation of Toluene to Benzaldehyde Ⅱ. Influence of Antimony on the Catalytic Properties of V_2O_5/TiO_2 Catalysts

Ｖ_２Ｏ_５／ＴｉＯ_２体系引入Ｓｂ后催化剂的活性受到抑制，但苯甲醛选择性有所提高．在Ｓｂ／Ｖ＝０．０８（原子比），反应温度６７３Ｋ，氧浓度７％，空速１４０００ｈ^（－１）时，甲苯转化率为２２．８％，苯甲醛选择性６９．７％，产率为１５．９％．运用ＸＲＤ、ＴＰＲ、ＴＰＤ考察了助剂锑对Ｖ_２Ｏ_５／ＴｉＯ_２催化剂体系的体相结构，表面酸碱性及其还原性能的影响．结果表明，Ｓｂ的引入有利于Ｖ_２Ｏ_５的分散，催化剂表面酸中心数目减少，强度减弱，及Ｖ_２Ｏ_５还原温度提高，而表面高分散的Ｖ_Ｏ_５还原峰随Ｓｂ添加量增加出现极大值，反应过程也能够使Ｖ_２Ｏ_５更分散，有利于甲苯的选择氧化．

When Sb content of V2O5/TiO2 catalyst increases, the activity decreases, but the selectivity to benzaldehyde increases. At Sb/V=0. 08 (atomic ratio), T = 673 K, oxygen content 7%, space velocity 14000 h-1 , the results of 22. 8% toluene conversion, 69.7% benzaldehyde selectivity and 15.9% benzaldehyde yield could be obtained. In this paper, some measurements such as XRD, TPR, TPD are applied to study the promotive influence of Sb on structure, acidity, basicity, and reducibility of V2O5/TiO2 catalysts. It was found that the additive Sb enhanced the dispersive abillty of V2O5on TiO2 and also lowered the number of acidic sites and acidity. The reduction temperature of vanadium ions of Sb-V-TiO2samples was much higher than that of V-TiO2. Reaction process made the V2O5 on TiO2 more dispersive, which would be advantageous to the selective oxidation of tolucnc.