环己烷直接氧化制丁二酸酐催化剂结构与催化性能研究

以气态环己烷催化氧化脱氢制丁二酸酐为目标反应，采用溶胶-凝胶法制备以TiO₂-Al₂O₃为复合载体的系列纳米催化剂，借助DTA-TG、FT-IR、TEM和XRD等测试手段对载体及其催化剂进行表征， 并进行活性评价。结果表明，复合载体中TiO₂基本上没有破坏γ-Al₂O₃的骨架结构，载体中的Al₂O₃和载体上V₂O₅的添加均能改变TiO₂的晶型转型温度。AlO与Ti—O相互作用后形成Al—O…Ti—O。在晶型转变的同时，可以实现V⁵⁺向V⁴⁺的转变，添加P₂O₅后，可以改变V⁵⁺/V⁴⁺。晶格氧是实现目标反应的供氧中心，V⁵⁺和V⁴⁺是其脱氢中心，当两种活性中心匹配时，可获得较高的转化率和选择性。

Direct catalytic oxidation of cyclohexane to butanedioic anhydride over composite nanocatalysts

Composite catalysts were obtained by sol-gel method using nanosized-TiO₂ supported on Al₂O₃ and V₂O₅ as the main active components. Butanedioic anhydride was synthesized by selective catalytic oxidation of gaseous cyclohexane over the catalysts. The supports and the nanocatalysts were characterized by DTA-TG, FT-IR, TEM and XRD. The results indicated that the cage structure of γ-Al₂O₃ were basically not affected by TiO₂ in the composite support; the crystallographic texture transformation temperature of TiO₂ could be changed by Al2O3-TiO2 interaction in the composite support and V₂O₅ on the composite support. Al—O…Ti—O bond formed due to interaction of AlO and Ti—O. V(Ⅴ) was transferred to V(Ⅳ) with the crystallographic texture transformation and V(Ⅴ)/V(Ⅳ) ratio was changed with doping of P₂O₅. Crystal lattice oxygen was the oxygen supply for the target reaction. V(Ⅴ) and V(Ⅳ) were dehydrogenization centers. Higher cyclohexane conversion and selectivity to butanedioic anhydride could be attained under appropriate matching of oxygen supply and dehydrogenization centers.